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January 28

Circuit simulation

Hi all,

what should I do if I try to stimulate this circuit via Nodal analysis? The article describes only the paper+pen method, but not how to tell a computer to simulate this. The SPICE and GNUCAP sourcecodes are both a total mess - uncommented and cluttered and so totally ununderstandable for a newcomer.

Any ideas on how to stimulate this circuit?

Thanks! 93.104.54.89 (talk) 02:53, 28 January 2010 (UTC)

That circuit doesn't really need to be simulated. It can be directly solved. SPICE and other circuit simulators are awfully complicated - much more complicated than actually solving this circuit by hand. Have you looked at series and parallel circuits? You can directly solve for the total resistance, and then solve for the total current, and thus, by applying Ohm's law, calculate the voltage at every node. Do you need help with this procedure? If you really want to, though, you can write a netlist and SPICE can give you the voltage at each node. Nimur (talk) 03:39, 28 January 2010 (UTC)

I am trying to write a simulator - the above-mentioned circuit just showed what I meant with nodal analysis - I am stuck. I can't figure out how to handle the split after R1 in a simulation :( I tried to understand SPICE and GnuCap source, but both are totally unreadable and uncommented. 93.104.54.89 (talk) 04:02, 28 January 2010 (UTC)

R2 and R3 are resistors in parallel, so you use the formula to determine the total resistance of 2 parallel resistors, and substitute R2 and R3 with a single value for that resistance. Do you need help with calculating the value of the resistance from R2 and R3? --Phil Holmes (talk) 09:43, 28 January 2010 (UTC)

Wikiversity can teach you about nodal analysis. Cuddlyable3 (talk) 12:49, 28 January 2010 (UTC)

Writing a general purpose solver for nodal analysis is not easy. First you need a method to represent nodes generally - e.g. a netlist syntax. Then, you need to write a parser engine to interpret the netlists in your format. You then need to convert the netlist to a system of equations, which may or may not be linear (depending on what you are simulating - circuits with only resistors, capacitors, and inductors are linear, but they rarely need simulation). Finally, you need a numerical solver for systems of equations. Are you very familiar with these concepts? If not, you might want to learn them extensively before you try to write a circuit-solving software package. In other words, there is a reason why SPICE's source code is incomprehensible to you - you've got to know the procedure before you can expect to understand the machine representation of that procedure! If you don't want to write a general-purpose solver, but only want to write a program to solve this circuit, then the best way to do that is to write out the defining equations and then plug those into a linear solver in matrix form (maybe GNU Octave). Finally, if you want to use SPICE, and don't want to learn how to write netlists by hand, you might be interested in existing schematic capture software, which will let you diagram the circuit graphically and then use SPICE to solve it. Again, let me reiterate - this simple circuit is so easy to solve by hand that learning SPICE or circuit capture is going to be much, much more work than simply solving on paper. If you're dead-set on simulation, you can purchase a SPICE or try your luck with gEDA, a free, free electronics design automation suite, available HERE. (I hate to say it, but this is one place where free software just doesn't make the grade - good SPICE isn't cheap). Nimur (talk) 20:12, 28 January 2010 (UTC)

Nuclear power

Why don't they use thorium reactors? They're cheap, clean, safe, and proliferation-resistant. --70.129.185.61 (talk) 03:29, 28 January 2010 (UTC)

Hightemperature thorium reactors for energy harvesting have yet unsolved problems in terms of security. it is mainly used for uranium manufacturing. 93.104.54.89 (talk) 04:17, 28 January 2010 (UTC)

Our Thorium article says there are advocates of same in India, and that there's some experiment underway in Moscow. THTR-300 is an article about the one that used to operate in Germany. The article is thin on the reasons why it was decommissioned. Comet Tuttle (talk) 05:57, 28 January 2010 (UTC)

Producers and regulators are more used to uranium reactors. Years of operating experience mean that the common problems and their solutions have already been found. For example, Areva claim "several thousand reactor-years of light water reactor operation worldwide"[1] when advertising their EPR. Nobody has that with Thorium reactors.

For a regulator's example, "The NRC has developed its current regulations on the basis of experience gained over the past 40 years from the design and operation of light-water reactor (LWR) facilities." [2] (emphasis added) AlmostReadytoFly (talk) 10:00, 28 January 2010 (UTC)

This is typical with English speakers: they assume they know everything. The german language article is more informative: there were problems with breakage of fuel rods and with recycling (that's why the one(s) in South Africa are designed differently). Finally, the last accident put a lid on it. --Ayacop (talk) 18:58, 28 January 2010 (UTC)

The problem with most "why don't they do X with nuclear technology" questions is that they are, once you add up all the costs, never as cheap or clean as they look on paper. As a result, countries tend to be pretty conservative—they go with what they have experience with. The experience with uranium-based reactors over the last fifty years has been that they are much more expensive than were estimated, and that their waste is a lot harder to isolate than originally seemed. --Mr.98 (talk) 13:58, 28 January 2010 (UTC)

True. Also, using load balancing technologies like thermal storage and pumped storage hydroelectricity you virtually eliminate the need for heavy baseline capacity. In 2005, wind was the least expensive form of new power, and while demand economics have intermittently changed that since, wind continues as one of the most profitable power investments, for good reasons, only a few of them having to do with flood costs.

Technically, all wind is solar in origin, and all solar power is nuclear. Which is why I think nuclear is a reasonable space power source for melting a comet captured inside an asteroid. Either that or black paint. 99.56.138.51 (talk) 16:34, 29 January 2010 (UTC)

Too bad we do not yet have feasible fusion power production like the sun. That makes fission look wimpy. Of course, if we are imagining, we should go for the gold and try for anti-matter power. Googlemeister (talk) 21:02, 29 January 2010 (UTC)

Not until we can do inertial confinement fusion, which is looking less and less likely all the time, based on neutron emissions. 99.56.138.51 (talk) 17:48, 1 February 2010 (UTC)

Placebo and Control

Hi everyone, this question's been stumping me for some time, so I was wondering if anyone could help me out. There's a study which is comparing the efficacy of two sleeping pills compared to not having any sleeping pills whatsoever. In order to make sure the pills are actually having an effect beyond the psychological, a placebo is also added. This results in four groups:

I - pill 1 II - pill 2 III - placebo IV - nothing (baseline)

But what would the control be in this case? Is it group III, IV or both of these? Thanks 121.216.118.27 (talk) 03:48, 28 January 2010 (UTC)

The control would be group IV, since the placebo effect would be a definate "result" in your experiment. A control sample is supposed to have no results at all. The belief that one might be taking a drug is itself an experimental variable, so you need a control group which contains absolutely no variables being tested at all. --Jayron32 04:30, 28 January 2010 (UTC)

I disagree. A control group needs to have absolutely all the variables the test group has, except the one you are interested in. If what you are interested in is the efficacy of a drug then the control group should be identical to the test group except you don't give them the drug. That means you give them a placebo. --Tango (talk) 04:34, 28 January 2010 (UTC)

There isn't usually a "nothing" group in this kind of study. Are you sure there is one for the study you are talking about? The only reason for having a "nothing" group is to see how much impact the placebo has. I do remember a study on anti-depressants that tested the drug, a placebo and nothing that had quite an interesting result - the improvement patients on anti-depressants showed was apparently 50% them getting better naturally, 40% placebo and only 10% the drugs (or numbers like that, I forget the exact figures). Most trials don't bother assessing the effectiveness of placebos, though. In fact, they often don't even include a placebo group and just compare the new drug with an established drug. That way you aren't making a third of your subjects go without treatment, which is rather unethical, and you really only need to know if the new drug is or isn't better than the existing one. If it's better than nothing but worse than the existing drug, it's still useless (unless you undercut the price of the existing one, which you usually can't). --Tango (talk) 04:34, 28 January 2010 (UTC)

In fact, I'm surprised the placebo is included at all. I was under the impression that commonly an existing and established drug will be used in place of the placebo. Of course with sleeping pills it isn't much of a life an death situation so perhaps they don't bother but then again, unless both are new drugs and the efficacy of neither has been established, it does seem a bit pointless to me. Edit: Ooops reading more closely see you already said that Nil Einne (talk) 08:13, 28 January 2010 (UTC)

A control is defined for a specific comparison, not for an experiment as a whole. For the drug1-vs-placebo and drug2-vs-placebo comparisons, the placebo is the control. For the placebo-vs-nothing comparison, nothing is the control. I agree that it would be unusual to have both placebo and nothing groups, but it isn't unheard of. Looie496 (talk) 17:17, 28 January 2010 (UTC)

For general interest: the use of placebos versus no treatment is found in a modest fraction of studies. It is from these studies that the existence of "placebo effects" have been meta-analyzed--PMID 20091554 — Scientizzle 17:31, 28 January 2010 (UTC)

It's true that the 'Nothing' group isn't really the control - but it is useful. Suppose, hypothetically, that your patients were so worried about having to take a pill that it kept them up all night worrying. It might well be that Pill 1 would prove to produce dramatically better sleep than Placebo - but if both of them produce worse results than "Nothing at all" then pill 1 is still not a good thing to give people. Since people do exhibit negative benefits from placebo as well as positive, I think the 'Nothing' group does provide useful data. Generally it's omitted because it provides less information than having a larger group size in the main test group and in the placebo group. SteveBaker (talk) 22:16, 28 January 2010 (UTC)

These answer kind of circle around the correct one: different controls are used for different drug trials, depending on several circumstances. 1. The simplest drug trial design is trial drug vs placebo. This is only appropriate when there are no other current treatments for the condition. This is usually unethical when there are any already existing treatments considered at least somewhat effective. 2. One of the most common drug trial designs is trial drug vs standard treatment for the condition. This is often referred to as a proof of non-inferiority, since in many cases the trial simply demonstrates that at least the patients do not do worse on the new drug. Sometimes the standard treatment is not an existing drug but a surgical procedure or some other treatment. 3. Trials comparing multiple drugs are usually used when the available patients are "real-world patients" in several centers. For example a new type 2 diabetes drug might be compared with patients using metformin and patients using insulin, but in these trials it may be more difficult to keep all of the relevant variable similar. alteripse (talk) 23:41, 28 January 2010 (UTC)

"Leave the rats in their cages" is one control, and "give the rats a placebo" is another control. Mere handling and being given an inert injection (or manipulation) might have some effect, attributed to the experimental variable, causing effects not seen when the subjects receive nothing at all. Applies to college sophomores as well. Entering a lab and encountering a "scientist" in a lab coat makes an impression on an experimental subject. A rat being placed in a testing chamber could have an effect compared to leaving her in her usual cage. Edison (talk) 05:35, 29 January 2010 (UTC)

power electronics

an scr turns off when the gating signal is not given? —Preceding unsigned comment added by Prasantsatpathy0174 (talk • contribs) 04:54, 28 January 2010 (UTC)

That is a statement with a question mark at the end of it, not a question. Are you asking if that statement is true? If so, and assuming I've correctly guessed which of the many possible meanings of "scr" you mean, you may find the answer here: Silicon-controlled rectifier. --Tango (talk) 06:06, 28 January 2010 (UTC)

...where you can read "The device will remain in the "on" state even after gate current is removed so long as current through the device remains above the holding current." which answers your question (if that's what it was). Cuddlyable3 (talk) 12:43, 28 January 2010 (UTC)

I think the OP could mean a Switched capacitor resistor, a totally different device which also has a gating signal. Nimur (talk) 20:40, 28 January 2010 (UTC)

Dont think he meant that as the question is headed 'power electronics'. He means Silicon (or semiconductor) Controlled Rectifier. —Preceding unsigned comment added by 79.76.251.94 (talk) 00:24, 29 January 2010 (UTC)

Minimum number of cameras needed for HD volumetric reconstruction?

I have one very good HD camera, but hope to see my films on a volumetric display eventually-perhaps ten years from now. Supposing I got a load of cheap low definition video cameras (or even web-cams) and placed them at various angles around the stage. Would it be feasible in software to reconstruct the full image in holographic full HD using the HD camera for detail and the multiple cheap cameras for depth information? I might just manage to get a second full HD camera as well. Also is there any software to extract depth information from an existing, good quality 2D video? —Preceding unsigned comment added by Trevor Loughlin (talk • contribs) 11:26, 28 January 2010 (UTC)

See http://en.wikipedia.org/wiki/3D_data_acquisition_and_object_reconstruction and http://en.wikipedia.org/wiki/Microsoft_Photosynth

I'm sure that in principle, 2 cameras can be used to reconstruct 3D information about whatever objects are seen by both cameras. —Preceding unsigned comment added by 83.134.173.152 (talk) 19:24, 28 January 2010 (UTC)

Remember, multiple 2D perspectives are not equivalent to true volumetric imaging. To truly volumetrically image, you need tomography or some other non-optical mechanism. However, it isn't clear what your intentions are, or what hypothetical 3D volumetric display technology you envision. In any case, even overwhelmingly oversampling the viewable stage with many views is not identical to capturing full 3D information - it depends on many factors, not the least of which is what objects block the field of view of each camera. You will only be able to reconstruct data which is in the union set of all your 2D images. Take a look at the concepts in graphical projection and think about how a camera stores information about a 3D scene. Again, stereoscopy, or even more than two perspectives, are not volumetric images. Nimur (talk) 20:45, 28 January 2010 (UTC)

It takes an infinite number of cameras for objects of arbitary complexity. Imagine a solid cube with a spiral-shaped hole disappearing inside it - like a snail shell or a spiral seashell. From the outside of the object - no camera can see around the corner of the spiral. So you'd have to have another camera down inside the curve of the hole in order to see around it. But that's only good for another quarter turn or so of the spiral before you're blocked again...for a long enough, thin enough, twisty-enough hole - you need an arbitary number of cameras. If you're only interested in things you could see from the outside of the object - then you can kinda/sorta get away with just a single camera if the object is on a turntable so it can rotate - or if the camera can move around the outside of the object. If you actually want to do this for real - I have a document on my personal Wiki that explains exactly how to do it - and even includes some software to get you started on building one yourself:

  http://www.sjbaker.org/wiki/index.php?title=A_Simple_3D_Scanner

Enjoy!

Of course there is another problem - extracting the 3D data from a bunch of 2D images requires there to be enough surface detail to make that possible. Also, because specular light will produce highlights in different places in each image. Because the camera can't really tell the difference between a shiney bit and an actual white patch painted onto the surface - there will always be ambiguity. But if you have an area of the object that's in deep shadow - there is literally no way to extract depth information from it. My scanner shines a laser onto the object to try to help this situation out - but it still fails miserably for very shiney objects. SteveBaker (talk) 22:04, 28 January 2010 (UTC)

I was considering posting some seismic tomography code, which does generate true 3D volumetric images using sound-waves, but it's pretty impractical for the hobbyist... fortunately Steve's laser scanner is a little more reasonable. A fun project would be writing an enhanced version of the Scan_Extract script/program. There's about ten thousand corner-cases I can think of - the simplest is a non-convex object - you have to use a lot of math or program logic to tesselate general-case 3D objects! Nimur (talk) 02:01, 29 January 2010 (UTC)

If you follow the link at the top of my wiki page, you'll find the ScanDraiD project over on SourceForge. That is the result of a bunch of guys taking my Scan_Extract program and doing precisely what you suggest. Sadly, I don't have the time to actively support that work - but it's certainly a worthy cause for anyone with software skills who is looking for an interesting problem. The program "as is" produces a crazy-dense grid of points - but because the laser image is continuous, you do have the complete surface shape in the source video...at least in principle. SteveBaker (talk) 02:53, 29 January 2010 (UTC)

I know of an application that does something similar to this(first query). The object to be 'scanned' was stationary at the centre of three cameras (one at 9, 12 and 3 o'clock), and a laser line scanner (or projector?) was then moved around the object an a big arm. A Silicon Graphics workstation did the processing, and a PC controlled cutting tool was used to cut a copy of the objects shape. (so it's not a HD or Video application but the principle is similar?) So you probably need at least 3 HD cameras plus a laser projector as also suggested by Steve. 3D scanner may be of some interest--220.101.28.25 (talk) 09:52, 29 January 2010 (UTC)

What's the difference between hairline skin and crown skin?

I saw the minoxidil product at the grocery store and the instructions said "For use on the crown only, not for receding hairline." Why? 20.137.18.50 (talk) 12:54, 28 January 2010 (UTC)

I don't know the answer to the first question (difference between hairline skin and crown skin) but the second question about the specific medicine is borderline medical advice (which we don't do here). If you ask a pharmacist, he or she should be able to tell you or direct you. Hope this helps. Falconus^{p t c} 15:38, 28 January 2010 (UTC)

Unfortunately our scalp article is not great at describing why the scalp's skin is much different, and I didn't see what I was looking for in skin either. Falconus^{p t c} 15:43, 28 January 2010 (UTC)

Thanks for looking. I'll ask the pharmacist next time. 20.137.18.50 (talk) 15:53, 28 January 2010 (UTC)

Minoxidil is only proven effective for one kind of hair loss, androgenic alopecia. Receding hairline is not the kind of hair loss it has been proven to help. -- kainaw™ 16:03, 28 January 2010 (UTC)

Yes, but "not being proven to help" is not the same as "being proven not to help". Wikiant (talk) 16:28, 28 January 2010 (UTC)

In the United States (where I am), you cannot market a medical product on the basis that it has not been proven not to help. Minoxidil is only proven to help with one kind of baldness. So, that is all it is marketed for. Therefore, the instructions only make a claim to help that one kind of baldness. If it helps with other kinds of baldness, then the manufacturers would certainly test it, prove it, and market it properly. -- kainaw™ 16:52, 28 January 2010 (UTC)

It is possible that it helps in the other type of baldness but inconsistently or consistently but only for some people. Under such circumstances, the FDA would not allow it to be labeled as "proven effective". Wikiant (talk) 17:57, 28 January 2010 (UTC)

Blood pressure and fitness

Say an unhealthy person who, through their diet and sedentary lifestyle, has high blood pressure. When they start exercising, particularily by doing cardio and fat-burning routines, I assume this activity helps to lower blood pressure. By what mechanism does this occur? Does the body "burn the fat" inside the arteries that are restricting blood flow? Do new capillaries get opened up? Does the heart strengthen and become more effective? Thanks. —Preceding unsigned comment added by 94.171.225.236 (talk) 13:18, 28 January 2010 (UTC)

Typically, aerobic exercise will increase the effectiveness of oxygen use in the body. The blood will be able to carry more oxygen. The effective use of the oxygen increases. So, less blood is required to get the same level of oxygen effectiveness. Therefore, lower blood pressure is required. -- kainaw™ 14:32, 28 January 2010 (UTC)

Probably there are also simple (but 'uninteresting' for research) mechanisms like helping the movement of the bowel will lower vegetative symptoms from obstipation (lowering release of catecholamines from the sympathic nervous system ).

Additionally, keeping a high muscle mass in old age won't let you collect fat in the wrong places (eating less does the same but who really is able to?), leading to the same obstipation with vegetative symptoms. --Ayacop (talk) 18:47, 28 January 2010 (UTC)

The answers above are incorrect. Read this article. Of note: "How physical activity positively affects BP is not known. One theory is that physical activity improves endothelial function. The endothelial lining of blood vessel walls maintains normal vasomotor tone.... Another theory proposes that exercise enhances shear stress..." (because of increased cardiac output) "stimulating the production of nitric oxide [and] smooth muscle relaxation.... There are also vascular structural changes." All of these mechanisms lead to a fall in systemic vascular resistance. Axl ¤ [Talk] 22:04, 29 January 2010 (UTC)

The Scientic Method

According to History of scientific method, it took centuries or even millenia to develop it. Is it now completely finished in its development? 89.242.92.249 (talk) 14:08, 28 January 2010 (UTC)

Isn't it obvious that to answer that we would have to know future events? Dauto (talk) 14:27, 28 January 2010 (UTC)

Some cathedrals took centuries to build. You do not have to look into the future to decide if they have been finished or not. 89.242.92.249 (talk) 14:39, 28 January 2010 (UTC)

The scientific method is not a building. It's not even a "thing"—it's a set of loosely-adhered to methodological strictures that guide particular forms of inquiry. The analogy is poor. There is no "finished state" of methodology. --Mr.98 (talk) 14:47, 28 January 2010 (UTC)

I guess the answer is that it is not yet fully understood or agreed and therefore not finished. Popper and Kuhn do not agree after all. --BozMo talk 14:43, 28 January 2010 (UTC)

So I'll never know if the development of GWBasic is finished or not? Another related question is how long ago the last development in the scientific method was? 89.242.92.249 (talk) 14:54, 28 January 2010 (UTC)

According to the article GWBasic's latest version was developed in 1988. There is no good reason to expect any further development now of such a low-performance (interpreted) program for outdated hardware that has no marketing potential, but I think you do know that. That issue is unrelated to the scientific method. Cuddlyable3 (talk) 14:58, 29 January 2010 (UTC)

Please cite your hard evidence that it is unrelated, even by analogy. Thanks. 78.149.152.46 (talk) 00:39, 30 January 2010 (UTC)

The scientific method is more like a busy town that a cathedral. The layout of the town centre is stable and does not change often or by much. On the other hand, there is always new building work going on in one or other of the suburbs. At the moment, there is a lot of new development going on in the demarcation problem area, for example. Gandalf61 (talk) 15:25, 28 January 2010 (UTC)

Is demarcation an inherent property of the scientific method? I would argue that it is more important to philosophers than to scientists. Surely the basics of the scientific method, being the use of experiments (as opposed to revealed truths and/or pure logic) to test hypotheses (to do this, the hypotheses must of course be testable by experiment, a.k.a. falsifiable) have not changed in the last few centuries. What has changed is people's understanding of the scientific method. Only now, we have written down a series of steps which constitute the "scientific method", but we're still doing basically the same thing Boyle did when he derived his Boyle's law. Even Isaac Newton, who mixed his science with a fair amount of mysticism, used the scientific method. The scientific method, after all, does not care what other beliefs you have, it will just keep working!

I don't think the scientific method ever changed, and I find it unlikely that it ever will. True, the ancients attempted to use other means to understand reality - but they succeeded only as far as they used the (modern) scientific method, and failed when they didn't. —Preceding unsigned comment added by 83.134.173.152 (talk) 18:06, 28 January 2010 (UTC)

Yeah - and getting past peer-review into the really serious journals was an absolute bitch in the Paleolithic. SteveBaker (talk) 03:37, 29 January 2010 (UTC)

I think it's still changing. In very minor ways - the rules for publication in various journals changes fairly frequently. It's becoming increasingly a part of the scientific method that one publishes data in a machine-readable form so that other scientists can access it. That was never true even 10 years ago. But the overall approach hasn't changed much: We are carefully, step-by-step building knowledge on solid foundations with checks and balances to try to ensure that nobody gets to stick a lump of jello in our slowly growing pile of solid stone slabs. It's not perfect - but it's by far the best way to get at "The Truth" that humanity has ever found. But it's not "finished". Mathematicians have a different standard of what makes a theorem than Physicists have for what constitutes a theory - which is different again from what a paleontologist would accept as proof that a new kind of dinosaur had been found. But the big picture is pretty much agreed upon. SteveBaker (talk) 21:57, 28 January 2010 (UTC)

The next step may be putting all the information in scientific journals in a way that the meaning can be "understood" by a computer, without a human having to read through them. Like the sematic web. 89.242.37.55 (talk) 01:58, 29 January 2010 (UTC)

I made a suggestion to do that with the information in Wikipedia as a part of the Wikimedia strategic planning process...sadly, the suggestion fell on deaf ears. I don't think they understood what I said.  :-( SteveBaker (talk) 02:40, 29 January 2010 (UTC)

Paradigms are always changing, as are scientific theories and ideas. For example it took 70 years for geologists to accept Alfred Wegener's then-new idea of continental drift which has evolved into the currently-accepted plate tectonics theory. ~AH1^(TCU) 03:12, 29 January 2010 (UTC)

Edited from "Wagener" to "Wegener" to change the link from red to blue: hope this is not deemed excessively presumptuous. 87.81.230.195 (talk) 10:06, 29 January 2010 (UTC)

You are NOT ALLOWED TO EDIT OTHER PEOPLES POSTS - PERIOD. Please read the ref desk guidelines and don't do it again. How do YOU know that AstroHurricane didn't actually mean someone called "Alfred Wagener" and now you've screwed up his post. You're are perfectly at liberty to create a response that says "Hey didn't you mean "Alfred Wegener"?" - but you must not edit other people's posts. The only exception is to fix egregious formatting errors that cause disruption to the readability of the ref.desk pages. SteveBaker (talk) 20:11, 29 January 2010 (UTC)

87.81.230.195 made a helpful correction where the context makes it clear that AstroHurricane001 really was referring to Alfred Wegener who IS the originator of the theory of continental drift, and 87.81.230.195 should be credited for politely explaining exactly what was changed such that no knowledge of AstroHurricane001's post has been lost. To accuse 87.81.230.195 harshly of "screwing up" AstroHurricane001's post is unwarranted. One can draw attention to a guideline without making a rant about it. Cuddlyable3 (talk) 23:47, 29 January 2010 (UTC)

"How do YOU know that AstroHurricane didn't actually mean someone called "Alfred Wagener" and now you've screwed up his post."

— SteveBaker

Seriously? Isn't it obvious to you from the context and the article "Alfred Wegener"? Since you have vociferously pointed out 87.81.230.195's transgression of the guidelines, I'll point out this section from the summary box: "It is a generally accepted standard that editors should attempt to follow, though it is best treated with common sense, and occasional exceptions may apply." [Emphasis mine.] 87.81.230.195 has used common sense and provided a transparent clarification of AstroHurricane001's mistake. 87.81.230.195 should be commended for this helpful correction. Axl ¤ [Talk] 23:44, 30 January 2010 (UTC)

Predator Fish Species in Farm Ponds

In farm ponds in the Southeastern United States, the major predator fish tends to be the Largemouth Bass. Some will have White or Black Crappie as well, but this is only recommended for bodies of water over 50 acres in size. I have wondered for a long time what other combinations would work. For instance, what if the major predator fish was Long-nosed Gar, Bowfin, or Chain Pickrel. Could these or any other species be used to maintain a heathly balance in a Pond of less than 50 acres? I have done a search of literature any have not been able to find any information. Does anyone have any insight into this or perhaps know of an article that would help me?--160.36.39.222 (talk) 14:23, 28 January 2010 (UTC)

SMOKING IS GOOD FOR YOUr mental health

But BAD FOR YOUr physical bioself. Lets say there was a ton of toxic chems (ie perservatative, pesticides, hormones) in our foodstuffs. And the action of inhaling smoke in our lungs, has a violent reaction in our immune system to boost it--that causes body to function by ignoring smaller toxins and go to attack the major toxin which would be the smoke in your lungs. In doing so, we get a euphoric feeling of healing. So my question is, considering a really gigantic controlled substance abuse of our normal foodstuffs, can smoking, in fact cause a negative reaction to our overall system, to turn off if you will the actions of all the chems in the food, and get your mind right? Right as in Fully Activated--for however long we inhale our smokestuffs. --i am the kwisatz haderach (talk) 18:03, 28 January 2010 (UTC)

I'm sorry, but that makes absolutely no sense. The good feeling you get when you smoke a cigarette is due to easing the withdrawal symptoms from your nicotine addiction, nothing more. --Tango (talk) 18:35, 28 January 2010 (UTC)

Well, that's not quite true: there is massive evidence that nicotine stimulates the brain's reward system in a way that is comparable to cocaine (but much weaker). It is however true that there is no basis whatsover for the idea proposed here. Looie496 (talk) 18:47, 28 January 2010 (UTC)

Your idea about the immune system is not true. The mechanism through which tobacco damages your body is well understood. Read about it in the article Health effects of tobacco#Mechanism. APL (talk) 19:03, 28 January 2010 (UTC)

Did I say Tobacco? Nay, just Smoke. I said smoke because I didn't want to bring in the entire druggy-lifestyle-is-cool-man motif, but since everyone is quick to think nic, lets say, you're smoking weed. Smokestuffs could be Marijuana cigarettes. --i am the kwisatz haderach (talk) 20:02, 28 January 2010 (UTC)

Even if you forget the drugs entirely and smoke, lets say, lawn clippings, It doesn't really change the health situation much. Your homegrown theory that it will stimulate your immune system, make you immune to certain chemicals in your food (Why would it only be the bad chemicals that you'd be immune to, by the way?), or "get your mind right." is completely false.

By the way, you seem to be under the impression that your immune system protects you from "chemicals". This is not generally the case. Your immune system protects against pathogens. APL (talk) 21:07, 28 January 2010 (UTC)

It doesn't matter much what you smoke - you're still getting carbon monoxide, tarry residues and who-knows-what chemical cocktail. So the distinction between smoking tobacco and (say) lawn clippings is mostly going to be that the lawn clippings probably don't have much nicotine - but nicotine is just the top of a gigantic pyramid of toxic and carcinogenic substances. If you're smoking any kind of plant-originated material whatever - you're going to die as a result unless you happen to be unlucky enough to die young of some other condition. SteveBaker (talk) 21:49, 28 January 2010 (UTC)

I don't think it's helpful to say that everyone who smokes anything is going to die young or as a result, because it's patently false. Using that sort of hyperbole, when people can easily see exceptions all around them, will lead people to totally disregard what you said. We are all going to die as a result of living. Some people are very lucky in terms of genes, and might live to the age of 80 with no Ill effects smoking 20 a day. Some people are going to find their lungs are destroyed at the age of 35 when they smoked 20 a week, and if they don't get a transplant some people are going to drown in their own fluids before they hit 40, even though they hardly smoked at all. We are only beginning to discover the genetic variations involved (I happen to know because one of the rare mutations that can leave you dead of passive smoke before your children are grown is in my family, but at least I know I can't be homozygous with it), and nobody can tell you what your personal genetic hand is on this issue. So, you would be well advised not to smoke, since your chances of being one of the lucky few who are relatively unaffected is very small, while the benefits of smoking, if any exist, can't outweigh the higher chance that it will leave you gasping for air that your lungs can't process when your friends are still in the prime of their lives. 86.180.52.43 (talk) 22:32, 28 January 2010 (UTC)

Lets say you ate some meat with "Mercury_(element)", aka poison, in it--which is a Diamagnetic, the Bioaccumulation of this and other magnetic elements in the body, I'm sure can cause Neurosis. Now at that, if we hooked a person up with the MRI, EEG, and/or EKG tests, and had this person smoke a cigarette at the same time, I'd like to know if the smoke inhalation would alter said tests. I'd also like to expand this question in that, if you did have magnetic poisons in your blood stream, wouldn't the MRI, EEG, EKG tests, the very Magnets of those tests, pull all of those poisons/toxins to that particular part of your body--closest to the magnets? --i am the kwisatz haderach (talk) 23:57, 28 January 2010 (UTC)

The brain is not simple, and does not function just in terms of good versus bad. Even assuming for a second that smoking helps the brain in some strange way (a concept that I disagree with), it is not like you can easily counter a problem with the nervous system by trying to increase whatever you feel is "good" for the brain. Even if you have a chemical that is truly good for the brain, there is no reason to suspect that it will do anything to counter the effects of mercury poisoning. At best, you have done nothing, at worst you have just added poisons to your body that is already not doing so great. Smoking is proven to add many poisons to one's body. Note that if your body is stressed (such as by a poison) it is, as I understand it, much more susceptible to cancer starting at that moment. Smoking carcinogens does not seem like a wise idea ever, especially if you are already sick. Falconus^{p t c} 06:22, 29 January 2010 (UTC)

And in any case, cigarette smoke contains up to 28 nanograms of mercury per cigarette in a particularly dangerous vapor form. It's certainly not going to help mercury poisoning! SteveBaker (talk) 07:18, 29 January 2010 (UTC)

There's also more to it than your body being vaguely stresses. Cigarette smoking will bring in other things from the air and deposit them deep in your lungs. Low levels of radon gas, for example, have very low chance of giving you cancer... unless you smoke around them, at which point, you have helped embed the really nasty radioactive bits in your lungs. Statistically, people who smoke and are exposed to radon gas have immensely greater risks of lung cancer than people who don't smoke and are exposed to it. The actual mechanism of smoking can create hazards for your lungs that wouldn't be there otherwise—and make small hazards into big ones. --Mr.98 (talk) 15:02, 29 January 2010 (UTC)

I'm not going to go back and forth--bandying words with everyone here, I'll just state that my question wasn't in regards to 'does Smoking Really give you Cancer' (my personal view is Placebo mixed with Gaia theory--if we all believe this to be the case, then it is human law), this was not my question. My question is in regards to the Neuro-Chem-Pyramid Effect, and placing Smoke, at the top of the pyramid, so that MAGNO-METALLICs in the blood--which are toxic, are right underneath smoking in this ‘poisons pyramid scale’ I'm envisioning. My question is in regards to the body ignoring the minor toxins for the major toxins--which is smoking. (which BTW, I agree with all the cancer stuff, because under my philosophy of Placebo-Gaia: the majority believe, and so too I believe.) Please in the future, really read my question thoughtfully, as a scientist maybe. The world has spoken, James Cameron's AVATAR is the Highest Grossing Film of All Time, so in that Gaia-ology, I'll quote from the film: "GOOD SCIENCE IS GOOD OBSERVATION ". --i am the kwisatz haderach (talk) 16:59, 29 January 2010 (UTC)

If your body ignored one problem to take care of another, it would be the same as if you were to ignore a problem in your everyday life. The problem would not go away. There would be no reason for it to. If I ingested a weak poison and then ingested a stronger poison, neither my body nor my mind would be rid of the weaker poison simply because my biological processes became focused elsewhere. Perhaps the pain of the stronger one would practically negate the pain of the weaker one.--160.36.39.222 (talk) 17:24, 29 January 2010 (UTC)

So, wait—you're going to posit some completely silly ideas that are based not at all in observation, not at all on even the slightest bit of research, and do so semi-incoherently, and then get unhappy when people don't just parrot back to you whatever it is you want to believe? We're the ones who are being unscientific, now? Smoking will not "get your mind right," will not boost your immune system, has nothing to do with "MAGNO-METALLICs" and does not have anything to do with Gaia. Sorry, but no. --Mr.98 (talk) 03:23, 30 January 2010 (UTC)

what could we do with unlimited free energy?

If we had literally free literally unlimited energy, what kind of applications would that enable? (One example: skyscrapers literally floating in air, continually held up at several different levels by helicopter rotors). That's just one example. What other examples are there that we could do with limitless free energy? Thanks. 84.153.238.207 (talk) 19:00, 28 January 2010 (UTC)

How limitless? Are we talking about a nuclear reactor that never needs fueling? Or a magic reactor that can give me any quantity of energy at a moment's notice?

For instance, if I built a machine that that needed the entire energy output of a thousand suns, could I just plug it into your proposed free energy machine? Or do I just get regular home electrical current ... but forever without paying a bill? I don't mean to nitpick, but these details drastically changes the answers. APL (talk) 19:09, 28 January 2010 (UTC)

Jerry Pournelle has stated that this would solve all human problems, for starters. Comet Tuttle (talk) 19:23, 28 January 2010 (UTC)

He would say that, even though it is patently absurd. Any accomplished SF reader or author should know that once you plug up one source of problems, new ones spill out from unexpected quarters. --Mr.98 (talk) 21:59, 28 January 2010 (UTC)

Ok, so switch that to all existing human problems. I'm not sure it's entirely true then, anyway - human nature won't have changed. A lot of conflict is over pride and power, rather than resources. --Tango (talk) 06:46, 29 January 2010 (UTC)

So my Susan would finally stop kissing that other guy? An entirely human problem and existing all over the world.93.132.164.32 (talk) 08:15, 29 January 2010 (UTC)

If you kill the other guy, or Susan or you get killed then that problem is solved although you may have new ones. Of course you can do that nowadays, but having unlimited energy likely makes it easier for you to deal with the possible consequences. This may not work if the other party uses their unlimited energy for some kind of scifi style energy shield, but we're still a long way from that but could probably design various weapons primarily using energy. The net result may be anarchy and even the destruction of the world which would I guess solve all human problems (no humans=no human problems) unless someone makes it to space in time as we suggested below Nil Einne (talk) 22:49, 3 April 2010 (UTC)

With limited, but free, energy you could, for example, provide enough desalinated water to green up Africa. You would also destroy all the worlds economy (although something else would probably arise instead), since at the end of the day the price of everything is determined by how much energy it takes to make it. You could create prefect recycling: Plasma arc waste disposal. Launches to orbit would be cheap enough that everyone would go. Super fast transportation would be so cheap that everyone would be going everywhere all the time. Good luck on maintaining the concept of separate countries in such a situation.

Now, if you had unlimited energy you could create matter, that would be a whole new world. Make enough antimatter, and interstellar ships are now practical. You would have enough energy to change the orbit of venus enough to cool it down.

Is your energy source small enough to carry with you? Then you could make personal flying machines. Ariel. (talk) 19:31, 28 January 2010 (UTC)

I don't think you would destroy the economy, but you would drastically change it. Basically the only limited resource would be human time, but that would still have value. That means, roughly, that agriculture and industry would disappear (or become really tiny - 1p for a week's food to cover the few humans involved in the process, perhaps), but services would remain (in a much altered form). --Tango (talk) 06:46, 29 January 2010 (UTC)

Not limitless by any means, but it would be good if there existed an enzyme that could reduce the activation energy of the reaction 2H2O -> 2H2 + O2. There's a lot of water on our planet and combustion of hydrogen gas can be used to do work. But electrolysis is very energy-expensive. 20.137.18.50 (talk) 19:32, 28 January 2010 (UTC)

I really never understood what's so hip about hydrogen. It needs an energy source to free it from oxygene in the first place and than gives nothing but trouble with safety, storing and combustion (volume gets less, not more when burnt). Don't get fooled by the fact that it does not create CO2 when burnt, the CO2 is freed from the primary energy sources needed that provide the energy for creating the H2 out of water. Unless you use atomic energy or have plenty of space for solar energy. In this case it would be far more practical to generate hydrocarbons as energy store. The only advantage of H2 over hydrocarbons is that it can be more easily used in fuel cells but afaik this is because fuel cell membranes are sensitive to contamination and H2 is cleaner than natural occuring hydrocarbons. 93.132.164.32 (talk) 08:08, 29 January 2010 (UTC)

You would have limitless energy if you could do that to any significant degree, because you could burn the products, and break the water in a cycle. Of course, that can't happen. Perhaps you could reduce the activation energy a little bit, but it's the enthalpy of formation of water that's your main problem with electrolysis, and you can't change that by even the tiniest amount. --Tardis (talk) 20:35, 28 January 2010 (UTC)

You would get a serious case of global warning, because where would all that energy go once it was used? Heat. You could melt the Antarctic icecap to make more land (to compensate for all the flooded land) Graeme Bartlett (talk) 20:44, 28 January 2010 (UTC)

But the fridges use energy, right? If I had enough energy I could freeze Milky Way (at expense of Andromeda galaxy) (Igny (talk) 20:52, 28 January 2010 (UTC))

You could sequester CO2 out of the atmosphere and store it together with some water in its most environment-friendly form as cellulose. No fear of sudden outgassing and plenty of useful things to do with it. If energy is really, really abundant and heat still is a problem, we could do like Pierson's Puppeteers and move our whole planet away from the sun. By the way, terraforming of other planets as well as deep space travel would be in reach. 93.132.164.32 (talk) 07:45, 29 January 2010 (UTC)

Indoor skiing in the desert comes to mind as the first needless use of unlimited free energy. Nimur (talk) 21:00, 28 January 2010 (UTC)

If someone gave me, as a gift, a fully fueled reactor from a nuclear sub, it would be more or less equivalent to someone giving me a free energy machine and then taking it away ten to twenty years later. I'd probably use it to power my TV.

That's the problem I have with questions like this. Without defining how you're getting the energy and what it's limitations are the answers could range anywhere from "Crush the entire universe to a singularity and cause a second Big Bang" to "Reheat a frozen pizza". APL (talk) 21:12, 28 January 2010 (UTC)

This is a silly question and we can't answer it. Thermodynamics says that energy is neither created nor destroyed. Hence, energy doesn't "go away" so as you use your limitless power source it's eventually going to wind up as waste heat. Before too long, you'd heat up the world to the point where you couldn't live in it anymore. But energy doesn't come from nowhere either - your infinite energy source would also have infinite mass - so it would be a black hole (at least) and actually it would be kinda tricky to get your energy out of the infinite energy source as a result!

These kinds of hypothetical questions where some part of the laws of physics are magically hand-waved away on the whim of our questioner never end well. When we throw up these kinds of objection, the OP comes back with more conditions and caveats to try to keep the question afloat - more and more important bits of physics have to be 'suspended' in order to keep the question alive. Eventually, it boils down to a situation where our questioner is merely manipulating the resident experts into producing an answer that (s)he wants to hear. So my advice is to just make up your own answer and leave us alone! It always comes down to the problem that unless ALL of the laws of physics are in there and working then we can't make any scientific predictions at all. The mere fact that your question involves a total scientific impossibility means that you can't possibly have a meaningful answer.

So my answer is "This is a silly question and we can't answer it" - and I'm standing by that!

SteveBaker (talk) 21:43, 28 January 2010 (UTC)

Just replace "energy" by "Fusion power plus enough fuel" and reread again. Then notion of Renewable energy wouldn't make sense when "energy" was always used in the strict sense of physics, would it?93.132.164.32 (talk) 08:24, 29 January 2010 (UTC)

The problem isn't how the energy is made - it's the word "Unlimited". Fusion power with finite fuel is far from "unlimited". Infinite fusion-generated power requires infinite fuel which gets you back to what I wrote. If the question is merely about large amounts of energy rather than unlimited amounts - then it had better put a cap on how much we're allowed to use. SteveBaker (talk) 20:07, 29 January 2010 (UTC)

Think of "unlimited" in the way natural numbers are unlimited: for any one of them there is a bigger one. And of course, even that is silly because the mass of the universe puts a limit. 95.115.151.113 (talk) 09:45, 31 January 2010 (UTC)

The question is sensible if nearly free and almost infinite energy sources are considered, for example, proposed fusion reactors. Forget about greening the desert-vast chambers with hundreds of underground levels could be lit to grow crops using artificial light (and using desalinated sea water) from the unlimited energy source, solving world hunger no matter what the eventual size of the world population was. Underground levels could be lit by artificial suns (think along the lines of the artificial environment in "The Truman Show") so urban sprawl and high rise "rabbit hutch" housing could be replaced by American dream style bungalows with gardens even for the poor. In effect the area of the planet would become more equivalent to its volume than surface area-but without an artificial sun and sky on each level, a troglodyte existence would of course be intolerable.Only a nearly free source of energy would make this practical. —Preceding unsigned comment added by Trevor Loughlin (talk • contribs) 05:06, 29 January 2010 (UTC)

If I were granted free almost unlimited energy wherever I chose to use it, I would build a starship, bid farewell to Earth, and take a few of my closest friends on a tour of numerous star systems, reaching within a gnat's eyelash of C at peak velocity by maintaining a constant acceleration of about 1 G. Edison (talk) 05:29, 29 January 2010 (UTC)

If I gave you a shoebox with an electrical outlet on it, and this outlet could produce as much current as you care to draw, how would you use that to build a starship in your lifespan? APL (talk) 05:37, 29 January 2010 (UTC)

Oh - that's easy! You go to the boss of NASA and say "I'll give you this amazing magic box - the study of which will be the saviour of all mankind if, in return you'll build me a starship". From that point on, things get very silly!  :-) SteveBaker (talk) 07:15, 29 January 2010 (UTC)

You can't solve world hunger with food. We grow more than enough food for everyone now, but there are still people going hungry. World hunger is caused by politics, not droughts. --Tango (talk) 06:46, 29 January 2010 (UTC)

However free energy can help (note I didn't say solve) some (note I didn't say all) of the problems which cause world hunger at the moment.

For example, one of the problems is transporting the food to the right places. This becomes a lot easier with free energy. Of course you may not even need to transport and this gets to another problem which is that many countries are reluctant to rely on other countries for their food supply, many of course can't even afford it. Poor countries are often affected by drought and other problems which cause drastically reduce their food supply. However with free energy sudddenly these problems grow a lot less dire (desalination for example) and it's a lot easier for whoever wants to, to grow whatever food they want.

This is all presuming this free energy is widely and easily available and not something people are going to fight over which is perhaps a big if.

I would add while this 'we grow more then enough food' thing is a common statement and does illustrate some points and has some truth, it's IMHO a little simplistic. [3] [4]

For starters, AFAIK people often tend to include all the grain etc we grow, calculate the energy available from that and say we could provide x kJ to each person per day with this amount of grain. Great in theory. Except of course a large part of it goes to feeding animals. This is wasteful and something recently receiving a lot of attention due to climate change however convincing people to reduce their consumption of animals is not easy and in fact in many parts of the developing world it's increasing as people get richer. So producing more food will make it easier to farm more animals. If you care about animal welfare, you may not like this (although some animal welfare issues could be reduced with free energy), but that's not particularly relevant.

There's also the issue of why food goes to waste. There tends to be this belief that a lot of food sits in warehouses and is thrown away because it gets too old. While this is surely partly true, I'm guessing it's also fairly simplistic. People tend to be fussy about what they eat, in parts of the Western world refusing many parts of animals for example, and this combined with food safety requirements mean what may be okay food is thrown away either before it gets to the warehouse or after it leaves (the consumers themselves probably play a big role in that, amongst other things, reasons of convenience means people tend to buy more then they need).

Food processing does enable the use of parts that seem unappertising however that costs including in energy and changing consumer demands is potentially reducing our ability to do that. And people tried to use bone meal as feed to reduce waste, look how that ended up...

In other words, the waste is coming from multiple areas that aren't easy to resolve and it's not so easy to just send it to starving people even ignoring distribution issues. And greater use of refrigeration as free energy will enable will likely greatly reduce waste anyway.

A simpler way of saying all that is that while it may be true we grow more then enough food to feed everyone, that doesn't mean growing more won't enable us to better feed everyone. In the real world, you can argue whether that's what we should be concentrating on but in this wonderworld, since you have free energy you can just grow more food and not worry about trying to prevent all that waste.

Of course there is also the question of what's valuable in a world of free energy. In theory, natural resources and land. But as some of the answers have illustrated, the importance of land is less clear when you can do silly things (although it still has importance). And even resources. People could mine them from asteroids, the sun etc. Or even make them themselves... In practice, using particle accelerators or nuclear reactions to generate particles you want is so outrageously expensive you'll never do it if you need quantities in bulk. But with free energy, you probably could.

In other words, I agree with SB here, this is a silly question we can't answer. The world would change drastically and presuming we survive the upheavel, what it would be like we can't say.

Nil Einne (talk) 07:47, 29 January 2010 (UTC)

We've pretty well covered the good things "unlimited free energy" could do. Going off past example (as per Mr.98, and human nature as per Tango) where such things are misused, I'm sure someone would use it to power weapons such as 'rail' guns (wear problems being solved) or huge Tera-Watt lasers, or find a way to use it in some other as yet unimagined way of killing/chopping/blowing us all up. Of course some defensive measures that are now limited by power availability become practical. (Shields up?) 220.101.28.25 (talk) 11:09, 29 January 2010 (UTC)

User 220.101.28.25 has rightly identified that the worst that humans can do with a powerful resource is what they will do, which is to hoard it and deny it to other humans. Such a scenario is explored in the novel Dune where the resource is a spice that confers cosmic powers and is simply the most essential commodity in the novel's fictional universe. People exploiting, and competing for, an unlimited energy source would probably lead to the same MADness as a nuclear confrontation and turn our fertile Earth into a ravaged desert. Cuddlyable3 (talk) 14:41, 29 January 2010 (UTC)

Yes, with unlimited free energy, we could transform the face of Arrakis! --Neptunerover (talk) 15:21, 29 January 2010 (UTC)

Save the Sandworm! Fremen against Terraforming --220.101.28.25 (talk) 20:16, 29 January 2010 (UTC)

People like the idea of a simple technological fix. But it never works out that way. There are always unintended consequences, and there are always resource allocation problems, and there is always politics sitting on top of that—basic human desires for power, sex, avarice. You will still have crazy religions, you will still have people who will organize for disorder, you will still have incompetence, you will still have idiocy, you will still have ridiculous tribal notions being expressed at a national (or planetary) scale. There are no utopias and can never be if you are considering them populated by actual human beings and not characters from Star Trek. Look around at the people around you, imagine them in your hypothetical world of the future, and imagine that they wouldn't bungle it up and create problems. The problems are more than technological in nature, and the solutions (if there are to be any) must be as well. And no solution is ever going to be final (thank goodness). --Mr.98 (talk) 15:11, 29 January 2010 (UTC)

Underground cities - all the nasty things like industry and prisons would be put underground. Cars would travel underground in tunnels. The surface would be a green quiet arcadia. Even the cheapest houses would have a small sun-room on the surface, and a large mansion deep under the earth with a fast lift between. I think any problems cured by unlimited energy would be replaced by a set of new problems. What would be far better would be an unlimited supply of intelligent robots. Energy is useless without the labour and intelligence to turn it in to something. With an unlimited supply of intelligent robots, then you woul;d see your wildest science-fiction fantasies, and a lot of extra wars as well. 89.241.39.207 (talk) 12:08, 30 January 2010 (UTC)

Has anyone mentioned desalination yet? "Large-scale desalination typically uses extremely large amounts of energy". The deserts would be greened. World hunger would be reduced until the increased population rate brought it back again with much higher crowding. 78.146.98.144 (talk) 16:00, 30 January 2010 (UTC)

In order, Ariel, Trevor then me. Anyway I didn't answer this old discussion primarily to say that but to point out this is one of the many streams of evidence how much nonsense all the crap free-energy conspiracy theorists spout is. Free energy isn't something scientists are scared of. It's like one big wet dream. Even for selfish people (whether scientists or whoever) as several people pointed out it's clearly to their benefit to find some way to hoard all that free energy rather then think they can magically supress it. Edit: And wow don't you love it when you come across an article on a relatively obscure and not exactly frequenly changing topic for completely unrelated reasons and it's been updated with recent developments from about 2 days ago, Eugene Mallove Nil Einne (talk) 18:07, 3 April 2010 (UTC)

neutron up quark color

Neutrons consist of thee quarks, two 'down'-flavored and one 'up'-flavored. The three quarks have a color charge, one of red, green and blue; there is only one of each color. Does it matter (and can we tell) what color the up quark is? CS Miller (talk) 20:56, 28 January 2010 (UTC)

The color is a not a color like you would see. It's just a label, a name to distinguish one from the other. It has nothing to do with visible color, you could call them zee, vee, and shmoo and it wouldn't change anything. (But see Color confinement and quantum chromodynamics.) Ariel. (talk) 21:51, 28 January 2010 (UTC)

The colours switch readily between the quarks. The force carriers of the strong nuclear force "carry" colour and anti-colour charges around. So the up could have any of the three colours at any time. EverGreg (talk) 22:04, 28 January 2010 (UTC)

Thank you. I knew the a quark (of ~1pm diameter) color charge property has nothing to do with ~400nm photons, that's why I used the term 'color charge'. The color-charge article suggested that colors can spontaneously change with the emission and absorption of an appropriately bi-colored gluon, but didn't give an indication of how often this occurs. CS Miller (talk) 22:31, 28 January 2010 (UTC)

Quark color is like a direction in a featureless three-dimensional space. The three quarks in a baryon (such as a neutron) have to point in orthogonal directions in that 3D space (they form a Cartesian coordinate system). Independently of that, you can choose an arbitrary Cartesian coordinate system and call its axes "red", "green" and "blue", but the colors of a particular triplet of quarks needn't align with those axes. There isn't even any way to say what colors you mean by "red", "green" and "blue", because the space of colors has no landmarks relative to which you can define them. Furthermore, quarks change color when they emit/absorb a gluon, so the colors of the quarks in a nucleon are not fixed; and, quantum mechanics being what it is, the colors are not definite even at a given moment of time.

Everything in particle physics is like this. "Up" and "down" (the quark types) are really two directions in a different three-dimensional space, and other directions make sense also. The difference is that the symmetry of the up-down space is broken, and so the up and down directions are unambiguously defined. But the strong force doesn't break that symmetry, and the strong force dominates inside a neutron, so it's actually problematic to even say that a neutron contains one up and two down quarks. -- BenRG (talk) 23:17, 28 January 2010 (UTC)

Ah thank you. I was assuming that an up-green quark was a specific type of quark, and would remain as that type until it interacted with another quantum particle. BTW is there a good layman's introduction to quantum theory? I think I understood Hawking's A Brief History of Time (on the third attempt), so something around that level would be ideal. CS Miller (talk) 13:17, 30 January 2010 (UTC)

are there quarks or strings- as per string hteory —Preceding unsigned comment added by Myownid420 (talk • contribs) 04:19, 30 January 2010 (UTC)

spores

can u get spores from a dead mushrooom thats been stored for a month? if so...how? —Preceding unsigned comment added by 76.14.125.132 (talk) 23:35, 28 January 2010 (UTC)

Possibly, depending on the conditions. Try making a spore print.--Shantavira|^{feed me} 13:05, 29 January 2010 (UTC)

Bird identification

What kind of bird is this? It is in the Ozarks on Missouri in January. -- kainaw™ 23:42, 28 January 2010 (UTC)

That's a northern flicker. We have one that comes to our backyard feeder every so often and it's a beautiful bird. Great that you got a photo of it. Yours looks like a male, yellow shafted variety. --- Medical geneticist (talk) 00:09, 29 January 2010 (UTC)

Thanks. I assumed that was the male. It's partner wasn't nearly as colorful, which made me assume it was the female. I also assumed the teeny little brown ones around them were the babies. -- kainaw™ 01:40, 29 January 2010 (UTC)

January 29

Bismuth

The article on bismuth says that it is more or less nontoxic. However, its only naturally occurring isotope decays into thallium, which is highly poisonous. Why isn't bismuth dangerous to handle as a result? --75.40.204.186 (talk) 01:23, 29 January 2010 (UTC)

It's half life 1.9 × 10¹⁹ years. Do you have any idea how long that is? Dauto (talk) 01:35, 29 January 2010 (UTC)

That's until half of it's thallium. Wouldn't a small amount of it be thallium before then? --75.40.204.186 (talk) 01:39, 29 January 2010 (UTC)

Well the question is then, is thallium harmful in extremely miniscule amounts? 219.102.221.49 (talk) 02:03, 29 January 2010 (UTC)

No, you don't understand - 1.9x10¹⁹ years is an amazingly long time - that's about a billion times the life of the universe! Even if that lump of Bismuth has been around since the literal dawn of time - the amount of thallium in there would be so small, it would be hard to measure. SteveBaker (talk) 02:33, 29 January 2010 (UTC)

Even if the thallium has accumulated over the last 5 billion years the concentration of thallium in bismuth is about 2.6*10^-10 - so even if you eat (?) 100 milligrams of bismuth you eat only 26 picograms of thallium - now what is the concentration of thallium in ordinary tap water? This abstract talks about several measurements, e.g. from not detected up to 8.4 nanograms/liter for Arctic snow. The natural background is estimated at 0.02 to 0.03 picograms/gram (20 to 30 picograms/liter) for the Arctic - so our 100 milligrams of bismuth won't hurt more thallium-wise than a liter of water from pre-industrial Arctic snow. Icek (talk) 06:30, 29 January 2010 (UTC)

Bacteria hitchhiking on manmade sattelites?

With planets like Mars or moons like Titan, we can't yet prove the non-existance of native primitive life, or "prebiotic organic goop", though we probably will in the near future. I'm just wondering if there isn't a chance that hardy bacteria/biochemicals from Earth may contaminate the surfaces of said planets/moons, assuming that some of the minerals and elements fundamental to life actually exist on their surfaces. It seems likely that, just as has happened on Earth countless times, an Earth (large and relatively welcoming and abundant source of life, thus allowing extremely varied forms to evolve) born micro-organism would be more likely to survive and wipe out an extra terrestrial (assuming a place like Mars or Titan, relatively unforgiving and unlikely to form varied or complex life) micro-organism due to the differing conditions of life.

Should I not be worried about that for some reason? Thanks! 219.102.221.49 (talk) 02:00, 29 January 2010 (UTC)

Yes, this has been worried about by serious people. The Mars lander was sterilized before being shot up into space to avoid this kind of problem. (And also to avoid accidentally detecting life... that it had brought with it.) I suspect—but do not know for a fact—that anything that is sent out of Earth orbit (a limited number of things) is probably sterilized first for this reason. Most manmade satellites run no risk of landing on other planets. This article though says that with the Voyager mission, for example, the craft itself was sterilized, but the upper stages of the rockets were not, and they are spinning around out there, somewhere, maybe with bacteria on them. Which is kind of non-ideal. --Mr.98 (talk) 02:10, 29 January 2010 (UTC)

This question, or ones similar to it, is asked about every 6 months or so. If you go through the archives, you should be able to find more info. Dismas|^(talk) 02:12, 29 January 2010 (UTC)

Ah, ok sorry, I usually check but I didn't think to this time around. Thanks for the answers! 219.102.221.49 (talk) 02:18, 29 January 2010 (UTC)

In the early years of space exploration, it was assumed that the harshness of the environment of space would "obviously" kill anything that might be alive on the craft. However, when the Apollo 12 moon walkers visited the site of Surveyor 3 an earlier robotic landing and brought back one of the cameras - it was a considerable surprise to discover that bacteria were still alive on its surface - although this report has been disputed (Reports of Streptococcus mitis on the moon). Either way, that shocked NASA and since then, spacecraft that are to land on other bodies in the solar system are carefully sterilized before launch. But even without that - it seems very unlikely that earthly bacteria released into what would certainly be an exceedingly hostile environment could out-perform the native species that would (presumably) have been living and evolving there for a billion years or more. Even if our own bacteria could survive there, a truly alien species would be so spectacularly different to anything we've ever seen that there would be no mistaking them from earthly lifeforms that escaped into their environment. Another strong possibility is that if there were someplace in the solar system where earthly bacteria could thrive in - then the very rare rocks that travel between bodies in the solar system would already have placed life from from any life-bearing body onto every other life-compatible body many times over the past few billions of years. Remember - rocks blasted from the surface of both Mars and the moon have been found just lying around right here on earth. If bacteria could survive in a hard vacuum alternately baked and frozen on the surface of the moon - then surviving a trip to Mars would be a walk in the park. SteveBaker (talk) 03:32, 29 January 2010 (UTC)

Two points here: I'm not 100 percent sure but I think Darwin would disagree with you on your point about earthly microbes not being able to compete with native microbes. On Earth, organisms highly adapted for specific environments (e.g. isolated islands) are extremely vulnerable to changes in fauna, and in cases where whole faunas evolve separately (e.g. northern and southern hemisphere arctic/temperate fauna), the tendency is for the larger to out-perform the smaller when they have a chance to meet. I don't see why organisms that were even more different wouldn't apply to these same principles. Then I guess the problem isn't that we wouldn't have trouble identifying the microbes as our own, but that our microbes would start to take up niches and to wipe out the native life! 210.254.117.185 (talk) 13:47, 29 January 2010 (UTC)

Or that life could be so spectacularly primitive that it couldn't compete with the bacteria. Think European powers colonizing during the 15-17th centuries.--92.251.222.63 (talk) 00:49, 30 January 2010 (UTC)

Only if they compete for the same thing, though. A truly alien life form would presumably be a lot more different and may hence use different resources. The difference in conditions between Mars and the Earth are also a lot more different than just the difference between a continent and an isolated island. A closer comparison is the one between a desert and a jungle, or between favourable and very unfavourable conditions; for instance, our own Earthly extremophiles are not endangered by our familiar household microbes. Besides, I'm under the impression that this sort of total, dramatic outcompeting mostly tends to happen with larger species.--91.148.159.4 (talk) 15:11, 1 February 2010 (UTC)

The relevant article is Planetary protection. Icek (talk) 06:16, 29 January 2010 (UTC)

From our animals in space article: "In September, 2007, during the European Space Agency's FOTON-M3 mission, tardigrades, also known as water-bears, were able to survive 10 days of exposure to open-space with only their natural protection." 75.41.110.200 (talk) 21:11, 29 January 2010 (UTC)

Questions on quantum mechanics

I am watching a set of lectures on quantum mechanics. So if I start beating down the door in here with questions, try not to beat on me; my education on Newtonian physics was very extremely half-done.

The lecturer is talking about the measuring sedentary electron with a magnetic field placed at either end. According to him, the electron will be "pointing" in a certain direction, namely towards the south. If the magnetic field is then altered at angle θ, then the electron has a likelihood of (1+cos(θ))/2 of emitting a packet of energy (or something like that... I'm inferring the equation... he hasn't gotten there); it is completely random, and it will either emit it, or it won't. If the angle is not changed, the packet will never be emitted; if it is placed at 180 degrees, it will always emit it.

I have two questions on this:

1. what sort of experiment can possibly be done to measure something on such a tiny scale? My brain wants to say this should be unmeasurable, given that we've already established that things on such a small level are, rather, random. I'd think Heisenberg might agree with me on some stage.
2. if the angle is altered by θ, and the photon is not emitted, and then then the magnetic field is readjusted by -θ to the original angle, what is the probability of the packet being emitted? Is it zero or have the probabilities been readjusted along the lines of the new quantum field? And if the packet is emitted, would the readjustment give a probability of 1 for another emission or a new probability based off the realignment?

I hope you don't have to read this question too many times to understand. :) Magog the Ogre (talk) 02:14, 29 January 2010 (UTC)

I was never much of an experimentalist, so I won't try to answer the first question, except to point out that the Stern–Gerlach experiment was an experiment of this type. As for the second question, I'm not sure I understand the details of your experiment, but it definitely constitutes a measurement of the electron spin along the axis of the magnetic field. After the measurement the spin can be treated as either aligned or antialigned with the magnetic field (depending on whether you saw a photon or not) regardless of which direction it pointed before. So when you then rotate the magnetic field by -θ and measure again, the chance of seeing a photon is (1–cos(θ))/2; nothing that happened prior to the previous measurement is relevant. -- BenRG (talk) 05:47, 29 January 2010 (UTC)

I think usually these experiments are done with a lot of particles, not just one. Not only does that make it easier to measure what's going on, but since it's effectively many trials running simultaneously we can find probabilities without having to do the experiment a lot of times in a row. However I think it is possible to measure single photons, like in the Quantum eraser experiment. Rckrone (talk) 07:38, 29 January 2010 (UTC)

Electron spin alignment (and changes to it, and specific energies involved, etc.) is the principle behind Electron paramagnetic resonance. DMacks (talk) 20:56, 29 January 2010 (UTC)

An optical (digital?) microscope

I am interested in buying a relatively small relatively inexpensive optical microscope to view micro-organisms living in/on the human body. Obviously there are very large and very small micro-organisms living in the body, but I'm not looking to look at "all" of them, just a "good number" of interesting little things that I wouldn't be able to see without a good microscope. For example, if I were to take a skin, cheek, saliva, or hair sample, could I realistically expect to be able to classify hundreds, or thousands of microbes with an easily obtainable home microscope? I'm thinking in the few-hundred-dollars range, not the few-thousand-dollars range. Any general information would be helpful, a lot of the brands don't seem to publicize their prices (national security?) and I'm not really sure how powerful/what features I need. I am in Canada, but it seems that I may have to purchase something like this in the US, which I can do if necessary. Thanks in advance! 219.102.221.49 (talk) 02:17, 29 January 2010 (UTC)

Hmm, I have a digital microscope that goes up to 200x it cost about AU$160. I have not looked into it much more then that but i have not seen digital microscopes with much better magnification. However I don't think 200x is enough to see micro-organisms, this is what a bee's face looks like, and this is a fly's wing. I've read that to see cells you need about 1000x-1200x, i have not seen a digital microscope with that power. optical ones i believe can be had for around $300 - $400. i think e-bay seems like a decent enough place to get them, students and all sorts of places off load perfectly good old microscopes all the time. I've been thinking of buying one one day but i need to learn a bit more about them before deciding exactly what to buy. I can't remember the exact name of the USB microscope i got, if you just do a search on e-bay you'll find it. Vespine (talk) 03:35, 29 January 2010 (UTC)

First off, unless you're using oil immersion optical microscopes (digital microscopes are a type of optical microscope) are limited to about 400x magnification. This is enough to see bacteria, although some of the finer detail are not likely to be visible. Secondly, even with high-powered microscopes, you're unlikely to be able to classify thousands of microbes without extra work. Most bacteria look the same rods/spheres/corkscrews. In order to identify bacteria, you usually need to stain them (Gram staining is the best known, but there are hundreds of other types used). That said, I'd try the Carolina Biological Supply Company (most school supply companies sell to hobbyist/home school market as well - check with the local science teachers about where they buy from). They sell a digital camera for ~US$230 that attaches to any regular microscope, or have dedicated digital ones for ~$270 (40x max). If you want a higher magnification than that, you need to go into the $1000+ range. -- 174.21.224.109 (talk) 06:56, 29 January 2010 (UTC)

Since when are dry optical microscopes limited to under 400x? I've owned cheapo $50 student microscopes that went up to 600x! You can get them at Walmart. Presumably this is not the level of quality that the question-asker is hoping for, but how can it be that the serious equipment you're talking about is going to be out-performed by what is essentially an educational toy? APL (talk) 07:04, 29 January 2010 (UTC)

From my experience, most lab grade optical microscopes have a 10x eye piece lens with a variable objective. Commonly this will have 1x, 10x, 40x and 100x objectives. Sometimes the 100x may be excluded. [5] If you use the 100x, you will usually need to use oil immersion if you want to have chance in hell of seeing anything and focusing (the lens be designed for oil immersion). As to why these cheap microscopes have 600x, at a guess 600x is starting to get to the limits where you ideally should be using oil immersion and they don't bother to follow tradition which 99% of lab optical microscopes do. Plus 600x sounds better then 400x. There's obviously no reason why you have to follow this tradition, but 600x is only 1.5x 400x and if it creates issues, plus is unstandard (so for example if you're looking at a picture in a book you may not find 600x) why bother? And most people would probably prefer to have a microscope with a high quality 40x objective lens then one with a shitty 60x one (or whatever). And from a biologists viewpoint I guess, if they do want to go to higher, why not just use the oil immersion? A bit messy and does require a fixed specimen but it's not really as hard or scary as it may seem. The only real big disadvantage is the inability to easily switch between objectives. Nil Einne (talk) 09:16, 29 January 2010 (UTC)

Looking at oil immersion, "State of the art objectives can have a numerical aperture of up to 0.95". This means that at 750nm, the resolving power would be 789nm. At 600x that would be 0.47mm. Rather difficult to see something apart at that level even if you had the resolving power I guess however seems to make sense to contemplate oil immersion. Not that the cheapo microscope is likely to have anything like 0.95 Nil Einne (talk) 09:32, 29 January 2010 (UTC)

P.S. The linked microscope has 900x not 600x. There's some discussions here [6] of the limitations of dry 900x magnification Nil Einne (talk) 09:45, 29 January 2010 (UTC)

To be clear, the maximum NA of 0.95 cited in that article is for air objectives — and those are going to have a very short working distance (space between the surface of the objective lens and the focal plane in the sample) or use a lot of very expensive glass. In practice, most standard-duty air objectives top out at an NA of around 0.75 and a 20x to 40x magnification. (The 10x eyepiece, as noted, is pretty much standard equipment.) For higher resolution and higher magnification, one moves to an immersion objective. Typical water immersion objectives (easier cleanup than oil immersion, though I don't know about their availability for hobbyist instruments) have an NA of around 1.2, while oil immersion objectives can squeeze out a bit more resolution (typically 1.3 to 1.4 NA.) Resolving power is governed by the numerical aperture of the objective lens (typically printed on the lens barrel, at least for good lenses). High magnfication factors are unsatisfying on a low-NA lens — features will be apparently 'larger', but blurry.

Incidentally, if you're planning on spending a lot of time at the microscope, consider purchasing one equipped with (or which can be upgraded to employ) a binocular eyepiece. For extended viewing sessions, the binocular eyepiece is significantly more comfortable than the one-eyed option. TenOfAllTrades(talk) 14:12, 29 January 2010 (UTC)

The idea that a brand of microscope might keep their prices secret for reasons of national security is curious. Is there a conspiracy theory here? Cuddlyable3 (talk) 10:50, 29 January 2010 (UTC)

You would need more than a microscope to identify bacteria at least. I think their classification and hence identification depends on how they stain - for example gramm-positive and gram-negative as far as I recall. I think I remember in the biology lab at school looking at some bacteria through a high powered professional microscope, but the bacteria was still just a tiny little dot. The "microbes" are going to be hidden among a lot of clutter of skin debris. If by microbes you mean bacteria, then you are be disapointed I think. For mites, fleas, and so on, then I expect you would be able to see much more. A drop of pond water should have lots of things in it. 78.149.152.46 (talk) 00:24, 30 January 2010 (UTC)

Yes, keep in mind that "microorganisms" and "cells" all range dramatically in size. For viruses, nothing short of an electron microscope will do. Bacteria can be seen with strong optical microscopes. But there are also many other organisms (such as in pond water) larger than bacteria but still too small to see with the naked eye, that can be easily seen with a low power optical microscope. As for cells, some plant cells are large enough to see without any magnification, and even some animal cells can be seen with little magnification (such as a human ovum). So, the result is that you can see something interesting at just about any magnification level. Therefore, you might do well to consider other factors, like how easy it is to focus in on an image, zoom, light it, etc., than be overly concerned with a high magnification factor. The ability to take pics using the microscope is also a nice feature. StuRat (talk) 20:04, 30 January 2010 (UTC)

magnetic piston thermodynamics.

Supposing a piston in a chamber enclosed in a sleeve of perfectly thermally insulating material was pulled down by a magnet such that the increasing resistance due to air compression was perfectly counteracted by the increasing pull of the magnet. When the air was fully compressed the temperature would have increased. If the insulating sleeve was removed heat could be extracted to do useful work.Bearing in mind that with the sleeve removed, ambient heat could get in the cylinder from outside,so the air would not cool much on the return stroke,would the piston be able to move back up as easily as it had moved down again, to repeat the process like a large scale version of Maxwell's Demon? —Preceding unsigned comment added by Trevor Loughlin (talk • contribs) 06:32, 29 January 2010 (UTC)

Certainly not - what you describe is a perpetual motion machine - and just like every single other efforts to build one of those devices, you're doomed to failure because the laws of thermodynamics says so. We don't need to understand WHY it doesn't work because thermodynamics is a handy shortcut. But I believe what happens is this:

• The piston falls and magnetic potential energy is converted into heat as the air is compressed.
• As the heat from the compressed air is removed, the air gets cooler and therefore denser but the mass of the air is the same - so it's volume must decrease.
• As the volume of the air decreases, so the piston falls a little more.
• Then the machine stops.

I don't see where this "return stroke" comes from. That would require energy because you'd be moving the piston further from the magnet. Where does this energy come from? The answer is that there isn't any spare energy lying around - so it's not going to have a "return stroke". The machine simply transforms the available magnetic potential energy into heat and then stops moving. SteveBaker (talk) 07:05, 29 January 2010 (UTC)

There is research into internal combustion engines that use a magnetic piston as a restoring force. I've seen numerous variants, for example, Linear motor, and ram accelerators. I'm not aware of any practical use of the latter system yet, but the fundamental idea is to extract energy from combustion and make the process cyclic with a restorative electromagnetic force. I think the OP's description fails to account for an energy input, so the process is not really an engine. Nimur (talk) 16:40, 29 January 2010 (UTC)

Yeah - it makes sense. You can often replace a spring with a sufficiently powerful magnet and that's good because magnets don't wear out or break - and where springs wear against the thing they are pushing against and need lubrication, magnets do not. With the advent of super-powerful rare-earth magnets, this becomes a viable possibility. Even more interesting is using an electromagnet so that you can control the force that's applied using a computer. But what the OP is discussing is perpetual motion...and that's an entirely different thing. SteveBaker (talk) 20:00, 29 January 2010 (UTC)

O.K. I admit defeat. But I still maintain that the second law of thermodynamics is unfair and should somehow be abolished.

I agree. Let's get our congressmen to do something about it. Buddy431 (talk) 18:49, 30 January 2010 (UTC)

Yes, the thermodynamic laws have a taste of unfairness to them. That has lead some people to describe them as follows

• 1st law: You can't win
• 2nd law: You can only loose
• 3rd law: You can't quit the game

Dauto (talk) 22:29, 30 January 2010 (UTC)

Most Green Company in the World

What company is the most green at present? Meaning, not only do they produce goods/services that are 'green' but their production/managment/etc is green also? --Reticuli88 (talk) 14:58, 29 January 2010 (UTC)

Editorial content: Such a flat term, is 'green'. It doesn't mean anything to me. Oh, I know what you'll say. The polar icecaps are melting. Fossil fuel is the way of the dinosaurs. Maybe, but so what? My town is not flooded. The cars I see are not running out of gas. The temperatures and weather are as mild as ever. Green schmeen. It's political hype, and as such I do not recognize your question as a valid one. Sorry! Vranak (talk) 15:05, 29 January 2010 (UTC)

I'm not sure if Vranak's reply is entirely a joke or not. But, in any case, I disagree. It is a valid Q. However, "green" is a rather vague term. Different people will have different ways of interpreting it. Let's just look at energy sources, for example. Pretty much all environmentalists will agree that burning fossil fuels is bad, with coal being the worst, and natural gas being the best fossil fuel. But how about burning wood ? Unlike fossil fuels, it is renewable, when responsibly harvested. However, it does release greenhouse gases and air pollution. How about nuclear power, then ? No air pollution there (unless you consider pollution released during construction and mining), but a very small amount of highly radioactive waste is produced. How about hydroelectric power, then ? Well, that involves massive dams which can flood out lots of historic sites and natural habitat, and also can prevent fish from being able to move up and down the river. How about wind and solar power, then ? Those seem fine on a small scale, but, on a large scale, would require a massive amount of land to be converted into what some will consider to be an eyesore. So, which power source is the most green ? It's all a matter of opinion. StuRat (talk) 15:41, 29 January 2010 (UTC)

It's not a joke. I don't joke! Or if I did, it would be funny. Vranak (talk) 17:39, 29 January 2010 (UTC)

I would rather have a sore eye than have to pay to clean up someone else's flood. 99.56.138.51 (talk) 19:02, 29 January 2010 (UTC)

I would say the National Ignition Facility is the most green, since if they succeed in making fusion power they will change the world. The most green company is the one that invents new tech to perform your preferred type of geenness. Ariel. (talk) 19:22, 29 January 2010 (UTC)

Is that a fact? Suppose the yield-rate of new technologies is sufficiently low that they actually consume more fossil-fuel than they offset by inventing new technology? Nimur (talk) 12:53, 30 January 2010 (UTC)

Agreed, ethanol production from corn kernels seems to fall into that category. When the effects of the lower fuel efficiency of ethanol and the increased cost of food are taken into account, ethanol from corn isn't any better than gasoline. Ethanol production from other sources, however, such as waste material, is quite promising. StuRat (talk) 19:41, 30 January 2010 (UTC)

Stinky drawers

My question is about laundry. Here's the scenario:

1) I wash my clothes, using bleach, and they smell good.

2) I put them in a dry drawer.

3) If I take them out in a few weeks, they smell fine. However, if I take them out 6 months later, they stink.

So, what causes this ? Mold and mildew seem unlikely, as the drawer is dry and the musty smell isn't what I associate with those things. Is it poop from dust mites I'm smelling ? I usually end up rewashing the clothes with bleach before I will wear them again. I've heard that putting a fabric softener sheet in the drawer will help, but is that just perfume masking the stink ? Any other suggestions ? StuRat (talk) 15:20, 29 January 2010 (UTC)

Use Space Bags. Dauto (talk) 15:28, 29 January 2010 (UTC)

I have a few issues with them: 1) Do the clothes get wrinkled ? 2) I don't always know ahead of time that clothes won't be used for a long period. If it's near the end of winter, I may wear winter clothes again, if we have some cold days, or may not wear them for 6 months, if it's warm from that point on. 3) Do you know that they stop the musty smell ? If it comes from a natural decomposition of the fibers, then maybe not. StuRat (talk) 15:58, 29 January 2010 (UTC)

Drawer liners are cheap and cover up the musty smell of old clothing. If you have any clothing that is made of biological material (ie: cotton or wool), expect a smell to build up around them if they sit a long time. As for scents, lavender has been chosen over many centuries as the optimal perfume to mask the musty clothes smell. I don't know why. I thought long ago that it would be a cool experiment to see what scents best mask musty smells. I personally replaced the bottom of all my drawers with a plank of cedar. They all come out smelling a bit woodsy, which meets my preference. -- kainaw™ 15:35, 29 January 2010 (UTC)

So, if I do that, people will all say that I smell like I spent the last 6 months in the woods ? :-) StuRat (talk) 16:02, 29 January 2010 (UTC)

My clothes are all cotton or cotton/poly blends. So, what exactly causes the musty smell with natural fibers ? StuRat (talk) 16:02, 29 January 2010 (UTC)

Sounds like some sort of mould to me. --TammyMoet (talk) 16:27, 29 January 2010 (UTC)

Cotton is a cellulose product. Like all cellulose products, it slowly breaks down in the presence of oxygen (and probably other gasses) and it is a delicacy for many small insects (moths, termites, and mites in general). If it breaks down, it produces a "musty" smell. If insects consume it, they produce a "musty" smell. There are *always* mites around. I don't think it is possible to have a home humans can live in without having mites. -- kainaw™ 16:27, 29 January 2010 (UTC)

Will they be present inside the Space Bags ? Would the partial vacuum kill them ? StuRat (talk) 16:34, 29 January 2010 (UTC)

The commercials say that they keep mites out. They don't make any claims about the survivability of mites inside the bags. I just did a google and there is so much marketing crap about dust mites that I don't think it is possible to get a valid answer about anything on the topic on the web. I saw one site that said taking garlic pills will make your skin flakes unpalatable to dust mites and they will leave your home. Complete nonsense. -- kainaw™ 17:46, 29 January 2010 (UTC)

They probably don't smell mustiness in a house full of garlic-eaters, or much or anything else, besides garlic. :-) StuRat (talk) 18:14, 29 January 2010 (UTC)

In my experience if you dry clothes in a drier, rather than in the fresh air and sun outdoors, they start to smell unpleasant after a while despite whatever perfumes are in the washing powder. How do you dry your clothes? 78.149.152.46 (talk) 00:17, 30 January 2010 (UTC)

IME I've used a tumble drier exclusively for 30 years and no unpleasant smells have accrued! It's got more to do with where the clothes are stored and under what conditions. --TammyMoet (talk) 09:11, 30 January 2010 (UTC)

I usually use line drying ie. in the sun. I'm wondering what effect the solar UV would have on any mico-organisms that may be left after washing? I imagine it would kill 'em well and good. Perhaps then reducing the chances of smelly clothes? --220.101.28.25 (talk) 11:53, 30 January 2010 (UTC)

UV doesn't penetrate very far, especially through dark fabric. So, I'd say it might do a nice job at sterilizing a thin, white sheet, but not at sterilizing the shadow side of a thick, dark towel. But, of course, there are also constant sources of contamination outside, like bird poo, insects, and dust blown in the wind, so the clothes may be recontaminated after they've been sterilized. StuRat (talk) 19:33, 30 January 2010 (UTC)

I machine dry my clothes, but do use bleach in the wash, so they are likely to be sterile when done (more likely than clothes dried outside with bird poop on them, I'd wager). The drawer where I place them, however, isn't sterile, and air also goes in and out of the drawer, potentially carrying more little nasties in. StuRat (talk) 19:24, 30 January 2010 (UTC)

Try Mothballs. Our birds are apparently well 'trained' and rarely crap on clothes --220.101.28.25 (talk) 00:26, 31 January 2010 (UTC)

But mothballs make the clothes stink, too. StuRat (talk) 01:55, 31 January 2010 (UTC)

Potpourri perhaps then? --220.101.28.25 (talk) 16:20, 1 February 2010 (UTC)

That would help with the smell, yes, but I'm still grossed out at the idea that my clothes are so full of dust mite poo that they need a stronger scent to mask it. This would likely make me rewash them, anyway. StuRat (talk) 20:00, 1 February 2010 (UTC)

A difficult undertaking

What does a mortician do when the vascular system of the body is no longer intact ? This would seem to be a problem for embalming, as both removing the blood and replacing it with embalming fluid would be difficult without an intact network of arteries and veins. Let's suppose that the head is intact, and an open casket funeral is desired, but the body is heavily damaged, perhaps by a series of shotgun blasts (in this scenario the deceased had apparently fallen out of favor with someone :-) ). StuRat (talk) 15:27, 29 January 2010 (UTC)

In an open coffin, the corpse is clothed. These clothes would not be the ones the deceased had died in, so the bullet holes would not be visible. An ex-student of mine, who was studying embalming (I was helping him with his English, before you ask) told me that he'd had to work on someone whom he couldn't embalm in the normal way for some reason (IIRC it was a car crash victim), and had had to embalm by immersion in formalin. Of course, this might not be the exact answer you're looking for! --TammyMoet (talk) 16:25, 29 January 2010 (UTC)

I thought about that method, but wouldn't such a body smell strongly of embalming fluid and thus be unsuitable for an open coffin ? StuRat (talk) 16:58, 29 January 2010 (UTC)

You could not embalm the corpse? Embalming is still rare in Britain and Ireland, and is not essential. Fribbler (talk) 17:28, 29 January 2010 (UTC)

Really ? I think either rapid embalming or cremation is required in the US, for public health reasons. Aren't Brits and the Irish concerned about spreading disease ? StuRat (talk) 18:09, 29 January 2010 (UTC)

Emblaming is not required by law in the US or Canada in most cases. Check any funeral director's web site in your jurisdiction for the laws in your area. Embalming is generally used if the funeral rites are to involve an open casket, as noted above. Notwithstanding that there are few legal requirements, most US and Canadiab bodies are embalmed. (I'll put some links in later today if no one else has by then.) Bielle (talk) 18:48, 29 January 2010 (UTC)

As promised, here are some links and more information:

This site looks at Canadian law and embalming and summarizes thus: “Does a dead body have to be embalmed, according to law? No. Most provinces, however, require embalming when death was caused by a reportable contagious disease or when remains are to be transported from one province to another by common carrier or if final disposition is not to be made within a prescribed number of hours”.

For the U.S. perspective, see here. The rules are similar: “Embalming is not routinely required by law, but may be necessary if death is due to certain diseases; if final disposition is not made within a prescribed period of time; if refrigeration or immediate burial is not available; or if a body is to be transported between states or internationally in a common carrier.

’Some states require embalming for transportation within the state, beyond the place where death occurred. Funeral directors may require embalming if the funeral ceremony selected by a family includes viewing, and they are generally required to ask permission of the deceased's next-of-kin verbally or in writing before embalming.”

There are religions where embalming is forbidden. I recall among them Orthodox Judaism, Islam and Bahai, though all would be subject to local law, with some exceptions. Bielle (talk) 01:48, 30 January 2010 (UTC)

The health risks from dead bodies are minimal in most cases. You can only catch disease from them if they had that disease when they died and, if they are kept on a mortuary slab and then put in a coffin, and you only touch them when wearing gloves (all of which is how dead bodies would normally be dealt with), then only air-borne infectious agents are a risk and that risk is no greater than the risk from a living person with that disease. Most contagions can't survive in a dead body for long, anyway. This recent BBC News article about the health risk from all the dead bodies in Haiti describes the matter in more detail (although the risk is obviously greater from bodies lying on the ground where they may in contact with water that people are drinking than it is from bodies in a coffin - the article still concludes that the risk is very small). --Tango (talk) 11:03, 30 January 2010 (UTC)

Thanks for all the info, everyone. So then, the only alternative way to embalm a body is by immersion in embalming fluid ? StuRat (talk) 19:28, 30 January 2010 (UTC)

I'm not sure the 'embalming fluid' would be able to adequately penetrate a body from simple immersion. --Neptunerover (talk) 23:55, 30 January 2010 (UTC)

Perhaps not normally, but the scenario I proposed has the body full of holes. StuRat (talk) 01:52, 31 January 2010 (UTC)

I see. That could make a difference, yes. --Neptunerover (talk) 08:18, 31 January 2010 (UTC)

Perhaps then a simple pickling in an alum and salt solution? --Neptunerover (talk) 08:21, 31 January 2010 (UTC)

Or in rum. Every man expects that England ... hic. BrainyBabe (talk) 10:04, 31 January 2010 (UTC)

I'm having me an All-U-Can-Eat Dolphin Meat-a-thon Dinner in Japan

I'll have the McDolphin-Mac please! Lets say I ate large portions of dolphin meat with "Mercury_(element)", aka poison, in it--which is a Diamagnetic, the Bioaccumulation of this magnetic element in the body, I'm sure can cause Neurosis. Afterwards I see my neuro doc friend and have fun with the MRI, EEG, and/or EKG tests. My question is this, if I have magnetic poisons in my blood stream, wouldn't the MRI, EEG, EKG tests, the very Magnets of those tests, pull all of those poisons/toxins to that particular part of the body--closest to the magnets? What kind of neuro-distruptions could this cause? --i am the kwisatz haderach (talk) 17:11, 29 January 2010 (UTC)

Diamagnetism causes a repulsive effect in the presence of a magnet. So even if the magnets had an effect, it wouldn't pull the Mercury to them.--160.36.39.222 (talk) 17:34, 29 January 2010 (UTC)

I am certain that I saw this on a TV show, though it may have been some other metal that had suffused the patient's body in this fictional thread. Doctors turned on the MRI, and zap! All the magnetic particles zapped right out of the patient's body, and he was a dead bloody mess. Comet Tuttle (talk) 17:43, 29 January 2010 (UTC)

If you had large enough magnetic particles in your body this might actually be possible. I can imagine having such large particles in the digestive tract, perhaps, but don't see how they would get anywhere else without you knowing it. Very small particles (like the iron in hemoglobin in the red blood cells) wouldn't be ripped from the body because the magnetic force on them is small compared to the other more local forces which hold the molecule together and in place. There might be an in-between region, where the particles do shoot out of the body, but the holes they leave are so small as to not cause any serious problems. After all, many substances can diffuse through intestinal walls, capillary walls, skin, etc., without causing any problem, as this is part of normal life. StuRat (talk) 18:06, 29 January 2010 (UTC)

The small enough particles, those ones moving around in your Brain region, I think that could disrupt normal synapses yes? --i am the kwisatz haderach (talk) 18:12, 29 January 2010 (UTC)

I would expect that any particles large enough to do that would be too large to diffuse through body membranes and get there in the first place, unless we imagine that many small magnetic particles would conglomerate together to form larger ones. StuRat (talk) 18:36, 29 January 2010 (UTC)

If this were true MRI machines would be deathtraps that killed anyone who walked past them, let alone got inside them. Clearly this is not the case, MRI complications almost always involve accidents with large chunks of metal (oxygen bottles for example) or bits of metal that have been implanted. Not microscopic particles that are floating through the body. APL (talk) 18:52, 29 January 2010 (UTC)

BTW, if you are really eating dolphin, you have more to worry about then mercury Dolphin drive hunting#Human health concerns Nil Einne (talk) 20:08, 29 January 2010 (UTC)

Metal-workers may have small metal particles embedded in their skin, eye, etc, either too small to notice at the time or remnants from incompletely removed pieces. Along the same lines, bullet-fragments or metal implants could be dislodged. DMacks (talk) 20:50, 29 January 2010 (UTC)

The Mythbusters did an actual test of this - the claim was that the iron in old-style tattoos could be ripped out of your skin. That idea came up in an episode of "House" too. House claimed it would be horrifically painful - Mythbusters claimed that there would be no effect. SteveBaker (talk) 02:26, 30 January 2010 (UTC)

P.S. For clarification, when I said 'worry about' I meant for reasons other then alleged negative effects when entering MRI machines Nil Einne (talk) 08:06, 30 January 2010 (UTC)

How much mercury is in a dolphin? Just for an order of magnitude idea, this article seems to imply it is around the range of 1.32 mg/kg. Let's say you ate, I don't know, three pounds of dolphin meat—which is kind of an extreme amount anyway. That gives you a mercury intake of about 4 mg. That's not very much mercury, from a magnetic standpoint, diffused in the bloodstream. Would an MRI be able to pick that up? I'm pretty dubious. You have much, much more iron in your blood than that—and this site gives a pretty good explanation why there aren't any significant magnetic effects on that. So, I'm no scientist, but it seems soooo unlikely to me that eating dolphins is going to have any MRI-based effects. (Much less EKG or EEG which don't use as big magnets, I don't believe.) The amount of mercury is just blindingly small from a physical standpoint (even if it is not from a biological standpoint). --Mr.98 (talk) 03:38, 30 January 2010 (UTC)

Swiss Climate

Haa Valley, Bhutan.

Where else in the world can you find a climate and topography similar to Switzerland? In particular towns running along river valleys surrounded on BOTH sides with huge mountains? But with lots of greenery during the spring so nowhere at extreme latitudes or elevations. Ideally not in Europe either (so Austria, southern Germany) would be uninteresting answers. TheFutureAwaits (talk) 17:27, 29 January 2010 (UTC)

Colorado ? StuRat (talk) 17:57, 29 January 2010 (UTC)

Thimphu, Bhutan comes to mind. --※Cōdell 19:35, 29 January 2010 (UTC)

New Zealand? Maybe?? (Never been there) --220.101.28.25 (talk) 20:38, 29 January 2010 (UTC)

Norway and British Columbia and the Scottish Highlands. Inland Japan as well. Vranak (talk) 21:29, 29 January 2010 (UTC)

Chile's lake district is often likened to Switzerland.--Eriastrum (talk) 20:53, 30 January 2010 (UTC)

Not quite sure what you mean. Are the towns essential to your vision or not? Plenty of places high enough to give you altitude sickness burst with verdancy in the spring. Kyrgyzstan likes to bill itself as the Switzerland of Central Asia -- that would be for the similarities in practices of Transhumance, not for the banking system. Some people like Kamchatka. Parts of Costa Rica have mountains with a climate similar to Switzerland's in the summer. Japan is highly mountainous, with most of the population crammed on the sea plains. Nepal and Tibet... one could go on and on. BrainyBabe (talk) 10:28, 31 January 2010 (UTC)

how does carbon dioxide poisoning induce lesioning and fluid discharge, etc.

Was reading some article where a patient described nasty sores and various discharges on his body after recovering from CO2 poisoning.... did he vomit while unconscious? Flail around? John Riemann Soong (talk) 17:28, 29 January 2010 (UTC)

Do you mean carbon monoxide poisoning? Dauto (talk) 17:34, 29 January 2010 (UTC)

Well I really mean carbon dioxide poisoning....e.g. from a limnic eruption. John Riemann Soong (talk) 17:47, 29 January 2010 (UTC)

Carbon dioxide isn't poisonous. It can suffocate though. Dauto (talk) 18:43, 29 January 2010 (UTC)

Carbon Dioxide disagrees with you 157.127.124.15 (talk) 19:18, 29 January 2010 (UTC)

That section needs some clarification; it says that CO2 at 8% will cause loss of consciousness, but it doesn't really say what the other 92% is. If the other 92% is ordinary air, that would still leave about 18% O2, which I think is still plenty to sustain consciousness, but I don't know just where the cutoff is.

Still, I think it's completely clear that if you try to breathe 80% CO2, 20% O2, you'll be fairly dead fairly quickly (but painfully), in spite of the fact that you're still being supplied with plenty of oxygen. Anyone who doubts it, just take a whiff right above the punch bowl that's bubbling from dry ice. If it feels like that in your nostrils, just imagine trying to fill your lungs with it. --Trovatore (talk) 23:16, 29 January 2010 (UTC)

Carbon dioxide is most certainly toxic above a certain threshold, regardless of the amount of oxygen in the air. CO₂, in the forms of bicarbonate and carbonic acid, acts to regulate the pH of the blood. An excess, however, can imbalance this system in favor of carbonic acid, lowering the blood pH and leading to a condition known as acidosis. – ClockworkSoul 05:39, 30 January 2010 (UTC)

An excess of carbon dioxide (even when there is a normal partial pressure of oxygen) is definitely toxic. As ClockworkSoul notes, elevated carbon dioxide levels can lead to acidosis and interfere with the oxygen-carrying capacity of hemoglobin. (See also hypercapnia and Bohr effect, along with Carbon dioxide#Toxicity.) At standard pressure, 10% carbon dioxide is quite lethal, even if the breathing mixture still contains 20% oxygen. TenOfAllTrades(talk) 05:53, 30 January 2010 (UTC)

From the article "Limnic eruption": "Many victims were found with blisters on their skin. This is believed to have been caused by pressure ulcers, which likely formed from the low levels of oxygen present in the blood of those asphyxiated by the carbon dioxide." Reference Axl ¤ [Talk] 19:28, 29 January 2010 (UTC)

NSA, FBI, CIA Automatic KEYWORD Internet Search for BODY of Electronic-Messages

I'm not sure if our Governments are really reading our e-mails. But if I wanted to send a Private Love Poem to my girl, and hypothetically I had a demented sense of humor, rhyming about 09.11, The World Trade Center falling, Al-Qaeda, things of this nature. Or even if I was really socially acceptable wordly heartfelt, and wanted to send a private Arabic poem, speaking of Muhammad’s Passion equaling the passion of my own heart, Peace be upon him. Could I just save my poem on a NOTEPAD file, and send as an attachment, maybe just put a ":)" in the body of the email, would this curb the ever watchful eyes of possible Government Security Protocol programs? --i am the kwisatz haderach (talk) 17:33, 29 January 2010 (UTC)

You don't seem to think very much of the top minds of the world's premiere surveillance organizations. Projects like ECHELON and Carnivore and its successors surely scan attachments, too. (IP traffic is scanned at a lower level, so it's not just e-mail, so really everything going across the wire would be scanned.) Encryption of your messages with a sufficiently long key is the only method that is presumed to save you from this eavesdropping. By the way, on your first point, when Usenet was the chat board and Reference Desk of the Internet, there used to be a script, allegedly popular (though I don't remember actually seeing it invoked), which would append an inflammatory randomized tag to every single post you wrote. Each post would end with a .sig including stuff like "Bring the shotguns. I will meet you at City Hall at noon." The juvenile point was to try to waste time of the surveillors, which at the time were presumed to be human. Comet Tuttle (talk) 17:49, 29 January 2010 (UTC)

It wasn't just "allegedly" - it definitely exists. It was a set of scripts that were shipped with the EMACS text editor called "Spook"[7]. It probably still exists. You hit ALT-X and then typed 'spook' and it would add all of these assumed-to-be-dangerous keywords into your email and someone on the other end who was reading the email using the same system ("UnSpook" IIRC) would not see them show up on the screen. It was thought that the spies would be so bombarded with false positives that they would be unable to function. Of course the world was a different place back then - personal privacy was a huge deal and terrorism wasn't. Doing a hack like that these days could get you into all sorts of deep doo-doo. SteveBaker (talk) 02:11, 30 January 2010 (UTC)

Yep - it still works. I just fired up emacs on my OpenSuse computer - and also on Windows 7 on my work computer. Typing Alt-X spook produced:

"Mantis cypherpunk Venezuela STARLAN Peking Skipjack world domination Vickie Weaver bce Perl-RSA Montenegro Attorney General Compsec Ron Brown smuggle"

...and under Win7...

"Ermes threat propaganda ANDVT pink noise Uzbekistan militia Montenegro rs9512c insurgency Crowell Delta Force Ft. Bragg jihad CIA"

...er SORRY nice Mr Echelon person sir - that was just a test! :-) SteveBaker (talk) 02:23, 30 January 2010 (UTC)

Awesome. Thanks. Comet Tuttle (talk) 19:13, 1 February 2010 (UTC)

(ec)

I'd say that they probably get billions of such e-mails flagged as being "of interest" due to the keywords. Most of those probably just languish in a huge database, as there is nobody to read them. However, if one of the people who is sent the e-mail happens to be on the terrorist watch list, then they might have enough interest to actually read it. StuRat (talk) 17:53, 29 January 2010 (UTC)

So a real bonifide terrorist, could just mispell words and or create Mafia slang, like calling things of terror Jellybeans, and if that became common criminal talk. In that Alternate Future, I titled my poetry "Jellybean", then I might bump myself up onto the watchlist. --i am the kwisatz haderach (talk) 18:08, 29 January 2010 (UTC)

Or just encrypt it. Or use code-words, sure. --Mr.98 (talk) 18:53, 29 January 2010 (UTC)

I think it's reasonably safe to assume that the CIA, NSA, MI6, whoever, are not the bungling idiots that you're imagining. But it's certainly true that THEY will never be able to effectively monitor all email because of problems with encryption, new channels of communication,cyphers, steganography, codes, etc. But don't worry about it. This is why those agencies employ spies. Spies are a tried and true intelligence gathering method that has worked reasonably well for thousands of years. Things like wiretapping and echelon are modern gimmicks by comparison. APL (talk) 18:59, 29 January 2010 (UTC)

You'd hope, right? But there is a lot of appeal to the "get all the info and 'connect the dots'" idea, even if its utility from a security point of view is low. And it is pretty well-documented that they make a lot of mistakes in this way (e.g. Ted Kennedy on the "no fly list"). --Mr.98 (talk) 19:07, 29 January 2010 (UTC)

Oh, I'm not saying that those things are worthless, or that our intelligence agents are saints and geniuses, I'm just saying that we don't need to panic just because the Internet can't be covertly monitored 24/7 with 100% accuracy. The spy agencies didn't throw away their spies when they got computers. (One assumes.) APL (talk) 19:17, 29 January 2010 (UTC)

On the question of using smileys... this came to mind. "Just because you put 'ha ha' doesn't make it funny!" :-) --Mr.98 (talk) 19:07, 29 January 2010 (UTC)

Mua'dib, The more you try to hide your message, perhaps the more interest 'they' will show in it. So send it in plaintext and they may ignore it totally. (Mr.98, you have to add a wink ;-) then they know you're not serious!) --220.101.28.25 (talk) 19:45, 29 January 2010 (UTC)

It's true that if you start sending out tons of encrypted files, that will probably attract attention of a scanner. Or maybe not. I don't know how common encryption is for e-mail, though I imagine it is pretty uncommon. Any e-mail based scheme is going to have some difficulties for passing secret messages that do not have the possibility of attracting the attention to whomever is sending the message (which is more of a threat than them breaking your encryption). --Mr.98 (talk) 20:15, 29 January 2010 (UTC)

OK, I came up with a better scheme. Basically you write a program that makes all of your secret messages look like spam. Then you send them from Hotmail accounts. Hidden! --Mr.98 (talk) 20:31, 29 January 2010 (UTC)

Um do you seriously think sending it as a plain ASCII (or whatever) txt attachment is going to in any way hinder surveillance? Nil Einne (talk) 20:05, 29 January 2010 (UTC)

It's more likely that they'll find one or two known terrorist sympathisers - find all of the people who send or receive email from them - then find all of them who talk to other people on that list. At this early stage, it doesn't matter what the messages say - the most interesting thing is the patterns of people who communicate with each other as a group. You only have to find one fairly low level person in that group and you can infer all of the rest. Once you have narrowed down your list of suspects, you can look back at all of the trillions of messages that ECHELON has been archiving and look for peaks of message traffic between these people around significant terrorist events. Without decrypting a single byte, they've pulled a net around perhaps just a handful of bad guys and maybe ten times more innocent people. By the time they have it reduced to that low level, they can attack the messages with code-breaking technology. Using alternative words for things is just another pretty poor encryption method and their algorithms can crack that. If there were messages around 9/11 between suspected badguys saying "Fly the two jellybeans into the two big enchiladas" - then code cracking methods can extract the real data just as easily as if the bad guys had replaced every 'A' with a 'B' every 'B' with a 'C' and so on. It's just a matter of having enough messages to crunch on. SteveBaker (talk) 02:11, 30 January 2010 (UTC)

Agree. See this article Traffic analysis --220.101.28.25 (talk) 12:09, 30 January 2010 (UTC)

Real bad guys, whether terrorist or merely criminal, would use commonplace substitutes for words indicating criminal intent. "Tell our friends, that we have decided to have the jagged edges smoothed down, and that we will pay $10" might mean "We agree to pay $10,000 to have two witnesses exterminated." Sadly, if I am the church's Property Chairman, and I email the rest of the Property Committee "I recommend we pay Don $12,500 to remove the loose plaster, replaster and paint the belfry walls. Our new traps eliminated two mice from the kitchen" it is likely to draw undue attention from the superspooks. Edison (talk) 03:55, 30 January 2010 (UTC)

The security issue is not, so much, the content, as it is the networks formed. This is why I think spamming would be a bit more ideal—a group of people send out large nets of information to large numbers of people, and only the "informed" person will know how to distinguish it as actually being secret ham rather than spam. It would make a much more complicated trail for anyone to try and "connect", especially if the scheme for distribution was based around certain random hotmail addresses (e.g., each message would send and receive only once... you'd have a series of addresses generated by a timecode or something). Spam is one of the few means of e-mail communication where we expect the senders and recipients to be kind of random spreads. It's kind of akin to writing on a bathroom wall in a crowded pub. --Mr.98 (talk) 15:51, 30 January 2010 (UTC)

hanging

The Hanged Man (tarot card)

According to the apocryphal Acts of Peter the saint was crucified hanging head down. Cuddlyable3 (talk) 18:47, 30 January 2010 (UTC)

if someone is hung upside down by their feet how long till they passout- note i said passout not die —Preceding unsigned comment added by 67.246.254.35 (talk) 18:03, 29 January 2010 (UTC)

I don't believe that they necessarily would; the human circulatory system (in healthy individuals) is capable of maintaining proper blood flow, even in odd bodily positions. --Ludwigs2 18:20, 29 January 2010 (UTC)

It depends, eventually everyone will go into shock if you hang them upside down long enough; the healthiest from dehydration. 99.56.138.51 (talk) 19:04, 29 January 2010 (UTC)

So why did that guy in Nutty Putty Cave die? Ariel. (talk) 19:17, 29 January 2010 (UTC)

"Utah County Sheriff Jim Tracy said Jones' exact cause of death will probably never be known but contributing factors likely included his inverted position for a prolonged period of time and the cave's cold temperatures."[8] Clarityfiend (talk) 04:23, 30 January 2010 (UTC)

Here is a news story relating to David Blaine#Dive of Death I found. He probably used tricks, but the quotes from doctors might be helpful. Ariel. (talk) 21:01, 29 January 2010 (UTC)

David Blaine is a magician. Magic Finally Revealed showed how it is done. 67.243.7.245 (talk) 05:11, 30 January 2010 (UTC)

I can think of several ways that an inverted position could cause death:

1) Stroke/anneurism/cerebral hemorrhage. The increased blood pressure in the head may cause any weak blood vessels there to burst.

2) Insufficient blood flow. Blood may pool in the head, and not circulate properly, ultimately leading to death from lack of oxygen to the brain.

3) Vomiting and aspiration of vomit could damage the lungs and/or block the airway, again preventing enough oxygen from being absorbed.

4) The way in which the body is suspended could itself cause a problem. Ropes around the feet, for example, could cut off circulation there, leading to gangrene and blood poisoning.

Of course, you asked about passing out, which I would expect to happen in each of these cases, some time before death. Stroke could happen immediately, while blood poisoning would likely take many days to develop.StuRat (talk) 19:03, 30 January 2010 (UTC)

one also has to consider complications. for instance, inverted hanging combined with significant exposure to cold or heat could put an undue strain on the circulatory system. --Ludwigs2 19:24, 30 January 2010 (UTC)

What's the term for the religious practice in India of being buried upside down in the ground for several days? ~AH1^(TCU) 03:15, 1 February 2010 (UTC)

Sun's position throughout the year

The sun is at the lowest solar declination on December 21 at -23.44°. After that date, the solar declination increases throughout the winter and spring. After June 21 or 22 depending on the year, which is the sun's highest declination at +23.44°, the solar declination decreases throughout the summer and autumn until December 21 or 22 depending on the year. Currently on January 29, 2010 the solar declination is -17.95°, which is the opposite of November 13, 2009. As the solar declination increases, then the sun's altitude in the sky increases or get higher in the sky in the northern hemisphere, whereas decreases in the southern hemisphere. The changing sun's altitude affects the amount of sunlight it gets into my house. All my kitchen and family windows face south. So as the solar declination increases, the amount of sunlight it gets into my kitchen and family room decreases, and vice versa. My house also has my arch windows in the kitchen, one facing at the azimuth of -165° and the other at -195°. For example, the sun shining through the arch window (or "archshine") on my basement door, as the solar declination increases the arch distance from the floor decreases or literally "the arch is going down". Whereas as the solar declination decreases, the arch distance from the floor increases or literally "the arch is going up".

There are informal terms of seasons when the specific solar declination changes:

• Winter: Norther in the Southern Hemisphere
• Spring: Norther in the Northern Hemisphere
• Summer: Souther in the Northern Hemisphere
• Autumn: Souther in the Southern Hemisphere

--BlueEarth (talk | contribs) 18:58, 29 January 2010 (UTC)

Having not seen your house, I would still tend to say correct; no question. 99.56.138.51 (talk) 19:07, 29 January 2010 (UTC)

BlueEarth has made a small error, and has also given us insufficient information.

He states that "Currently on January 29, 2010 the solar declination is -17.95°, which is the opposite of November 13, 2009." No. On those two dates the declination was the same, not opposite. What was opposite was the direction the sun was moving. In November it was moving southward, in January, northward.

I have no idea where your house is located. If you are north of the Tropic of Cancer, the noon sun is always to your south. B00P (talk) 01:27, 30 January 2010 (UTC)

... and this only works with seasons as defined in the USA. Elsewhere, they are often differently defined. Dbfirs 07:56, 30 January 2010 (UTC)

Rally? I never heard of any alternate definitions for the seasons. Could you give us an example? Dauto (talk) 15:06, 30 January 2010 (UTC)

Many places have a wet, or monsoon season, and a dry season, if that's what was meant. StuRat (talk) 20:32, 30 January 2010 (UTC)

No, I meant Spring (season), Summer, Autumn & Winter which are not, elsewhere, defined as they are in the USA. Dbfirs 17:56, 31 January 2010 (UTC)

Sorry, I should said 'same as November 13, 2009' instead of 'opposite of November 13, 2009. My house is located in Tinley Park, Illinois near Chicago. BlueEarth (talk | contribs) 23:58, 30 January 2010 (UTC)

Good. And now that we've got that cleared up, what is your question? B00P (talk) 17:04, 31 January 2010 (UTC)

Pluto's atmosphere

Pluto is made of frozen gases. When sun heats up what makes people think it will get outgassing that quickly. The frozen gas do become an atmosphere when anti-greenhouse effect goes down. When molecule moves faster then frozen nitrogen gas wilol sublime into envelopes of atmosphere and it will end up ilike Titan (moon) now.--209.129.85.4 (talk) 20:52, 29 January 2010 (UTC)

The gas can escape quickly because the gravity of Pluto is low. Take a look at atmospheric escape - the type of gas, temperature, and gravity all affect the rate which gas escapes into outer space. I can't understand your question about "anti-greenhouse effect" - can you elaborate? Nimur (talk) 21:19, 29 January 2010 (UTC)

When sun heats up Mars can heat up to build an atmosphere though Mars have no magnetosp. This is a google page, some users may have access to it but it is properly cite.--209.129.85.4 (talk) 21:45, 29 January 2010 (UTC)

Also consider that Pluto has a huge moon, Charon (moon), and two smaller moons. This may increase outgassing in several ways:

1) Charon presumably has less gravity, so outgassing from it is more likely. It may not be possible to determine, from Earth, whether outgassing is from Pluto or Charon.

2) Tidal effects between Charon and Pluto may cause both to heat up somewhat. That is, unless they are dual tidally locked. Our article says that they are, but I would guess that's just an assumption due to their relative masses and distance. If one was recently perturbed by a major impact, this may not be the case.

3) The apparent gravity on the side of Pluto closest to Charon (and vice-versa) may be significantly less, allowing for more outgassing. StuRat (talk) 18:42, 30 January 2010 (UTC)

Correction to the original statement: Pluto is not made of frozen gases. Comet Tuttle (talk) 06:09, 1 February 2010 (UTC)

visibility on the moon

If you were an Apollo astronaut standing on the moon, what is the smallest object you could see on earth (unaided, assuming daylight on earth, no clouds in the way)? Would Australia be visible? Madagascar? Great Britain? Cuba? Malta? Smaller? Googlemeister (talk) 22:02, 29 January 2010 (UTC)

The smallest resolvable element would be about 150 km in size. I'll leave as an exercise for the reader to figure out what a good example is. Dragons flight (talk) 23:03, 29 January 2010 (UTC)

Specifically, at Naked eye#Basic accuracies the limit of resolution of the eye is given as about 1-2' (1 to 2 minutes of arc). At the distance of the moon 1' corresponds to 68 miles or 110 km. The low contrast between green or brown land and blue sea would make it harder to distinguish fine details, particularly when the brilliant white clouds in other places draw your attention. It's think in most places the best you could do would probably be 2' or maybe even larger. Seeing Malta would probably be marginal; Madagascar or Great Britain should be easy under good conditions. --Anonymous, 01:18 UTC, January 30, 2010.

I hope Australia would be visible, but this (not from the Moon unfortunately) suggests there are times when it may not be very visible, but is still there. Oz is in the right picture, lower right edge. I would wave but you can only see Perth in this piccy. Boo Hoo, sniff --220.101.28.25 (talk) 23:39, 29 January 2010 (UTC)

Yes - but that photo is misleading. From the perspective of someone standing on the moon, the earth would maybe be no wider than your thumb at arm's length. So unless you are reading this on your iPhone, you might have to stand a fair way back from your computer screen to get the right idea of what you'd be able to see. SteveBaker (talk) 01:49, 30 January 2010 (UTC)

At the risk of stating the blindingly obvious, the Earth as viewed from the moon should appear 3.7 times larger across than the moon does when viewed from the Earth. Dragons flight (talk) 02:33, 30 January 2010 (UTC)

How about this piccy then? Better? --220.101.28.25 (talk) 03:07, 30 January 2010 (UTC)

What's not obvious, so should have been stated, is that "your thumb at arm's length" is the standard description of the angular diameter of the moon from Earth. That is what makes your comment relevant! Steve got a little confused, it seems. --Tango (talk) 13:21, 30 January 2010 (UTC)

No, "your thumb's width at arm's length" is the standard description of one degree. The Moon subtends half a degree. --99.237.234.104 (talk) 04:49, 31 January 2010 (UTC)

It's worth mentioning that this is also the smallest object you can see on the moon from the comfort of your own back yard...assuming night on earth and no clouds in the way. That would allow you to just about spot Babbage. Incidentally - the astronauts all had close to perfect vision - it was a significant qualifying factor for the moon missions. So from the earlier answers, I think 70km would be a good number. Orders of magnitude (length) (I just love all of those "Orders of magnitude" articles...they are great for answering these kinds of question!) says that you'd be able to see the Bering Strait - but not the Strait of Gibraltar. You would be able to spot some of the worlds largest cities - NewYork with all of it's suburbs, for example should be just about visible. SteveBaker (talk) 01:46, 30 January 2010 (UTC)

I suspect the contrast ratio of urban development would be too low to differentiate it from undeveloped land. This NASA discussion about visibility from low earth orbit brings up some interesting points. Nimur (talk) 13:04, 30 January 2010 (UTC)

It would be much easier at night - you could almost certainly see a bright spot in the light pollution that corresponds with New York. --Tango (talk) 13:21, 30 January 2010 (UTC)

So NYC is both a literal bright spot and a metaphorical dark spot, when it comes to light pollution. StuRat (talk) 18:34, 30 January 2010 (UTC)

Yes, light pollution is poetically problematic! --Tango (talk) 20:45, 30 January 2010 (UTC)

How much heat loss through a door slightly open?

My home thermostat is set to 72 degrees and it's 26 degrees outside, if my wife goes outside and leaves an otherwise well insulated door about a crack (about 1/4 inch) for 5 minutes how can I get a rough approximation of the heat lost, or more specifically the cost of replacing that lost heat. My house uses natural gas for heat, not sure of current rate. Don't want to argue with the mrs if it is only few pennies! 205.157.110.11 (talk) 22:30, 29 January 2010 (UTC)

I just stopped at "72 degrees" and melted into a large puddle. :-) Bielle (talk) 22:34, 29 January 2010 (UTC)

It is almost certainly less than a penny per five minute episode. Dragons flight (talk) 23:20, 29 January 2010 (UTC)

Temperatures in Fahrenheit I presume? Though it probably makes no difference to the question. 220.101.28.25 (talk) 23:45, 29 January 2010 (UTC)

Since you said 72° and 1/4 inch, just for fun I'll do this in non-metric units. Say the door is 7 feet high; then the opening is 21 square inches. Say that cold air comes in through the crack at 15 mph (a pretty high estimate in most weather conditions) for 5 minutes. Then the total volume of air is 21 × 15 × 5 square inch mile minutes per hour, which is about 960 cubic feet according to units (software). The volumetric heat capacity of air at the freezing point is about 0.0013 J/cm³·K, which is about 0.019 BTU/ft³·°F. So assuming that this remains reasonably constant through the temperature range, to raise the air from 26° to 72° you need 960×(72-26)×0.019 = 840 BTU of heat.

Googling on "cost per BTU", the first web page I hit says that burning one cubic foot of gas yields about 1,000 BTU. On my last gas bill I paid about $70 Canadian, plus 5% tax, for 212 m³ of gas, which is about 7,500 cubic feet, so one extra cubic foot would cost me almost exactly 1¢.

--Anonymous, 23:52 UTC, January 29, 2010.

Wow awesome responses, thank you all —Preceding unsigned comment added by 205.157.110.11 (talk) 00:59, 30 January 2010 (UTC)

Anonymous' math seems impeccable...and if the door remains just 1/4" ajar, it's obviously no big deal. Of course if the door is open 1/2", that doubles the cost, one inch and it doubles again. My main concern is that if the door is not latched then if the wind catches it and blows it all the way open then the gap is now about 30" wide - so the loss would be $1.20 which would certainly get noticable if it happens several times a week. However, at that scale, there comes a point where all of the warm air in the room disappears outside and the subsequent cost is limited by the amount of time the heating remains on with the door wide open plus the cost of raising the heat back up to 72 degrees after the door is eventually shut again. In that case, the size of the room becomes a limiting factor. So I think it's worth keeping it shut, just on general principles...but it's not worth creating a major family ruckus about. SteveBaker (talk) 01:22, 30 January 2010 (UTC)

I would object loudly to someone creating a 21 square inch (135 sq cm) opening to the outside when the outside temperature was 26 F (-3 C). The proper utterance would be: "Wuz you raised in a Barn? Shet the damn door! Edison (talk) 03:46, 30 January 2010 (UTC)

... plus the psychological effects of the draught created by an open door are percieved as much more uncomfortable than would be expected from the actual reduction in temperature. Dbfirs 07:46, 30 January 2010 (UTC)

Not just psychological; your body physically loses heat more quickly in moving air, by evaporation and convection - the Windchill effect. Alansplodge (talk) 09:44, 30 January 2010 (UTC)

When the hole doubles in area, does it really lose only double the heat? Is it really linear? 95.112.174.46 (talk) 16:55, 30 January 2010 (UTC)

Yea, I question that, too. I believe that heat loss due to radiation and conduction would indeed be close to linear. However, convection losses and those due to wind would not, and those would be a major component of the total heat loss.

I'm also curious as to why the door is left open a quarter inch. My guess is that the door automatically locks when latched. If so, one suggestion is to add a storm door that automatically closes, but doesn't automatically lock. StuRat (talk) 18:26, 30 January 2010 (UTC)

January 30

itching

Why do we itch ? what is the reason behind itching? Why do we yawn ? i know that it is surly not for taking much air. —Preceding unsigned comment added by Myownid420 (talk • contribs) 04:15, 30 January 2010 (UTC)

One possible reason for itching is parasites, though perhaps you meant scratching? See also yawn --220.101.28.25 (talk) 04:34, 30 January 2010 (UTC)

Yes, itching is to alert us to a potential problem on the skin, such as bugs. I've often felt a mosquito on my skin and swatted it dead before it could inject me with it's bacteria and virus cocktail. While parasites may seem like a minor annoyance to us now, ridding ourselves of them, or at least limiting damage from them, was absolutely essential to life for much of human (and pre-human) history. Thus, there was a strong evolutionary incentive to develop the itch and scratch defense. Of course, the system does sometimes go wrong, and we end up damaging our skin, as in the case of meth addicts. StuRat (talk) 18:16, 30 January 2010 (UTC)

See itch.--Shantavira|^{feed me} 10:01, 30 January 2010 (UTC)

Itching can be caused by diseased skin. --Neptunerover (talk) 16:09, 30 January 2010 (UTC)

According to a certain Buddhist teaching, the pleasure gained from scratching diseased skin is comparable to that which is obtainable in Samsara. I have not heard any direct reference to Samsara actually causing itching, although that alone would not preclude it from being one possible reason behind itching (No one can say there's only one reason, anyway). --Neptunerover (talk) 16:29, 30 January 2010 (UTC)

Samsara [9] would cause itching in people who are sensitive to some of its ingredients. --TammyMoet (talk) 18:15, 30 January 2010 (UTC)

Indeed, that could potentially cause itching, sneezing, and maybe even some vomiting. It all depends on one's sensitivity. ;)--Neptunerover (talk) 09:02, 31 January 2010 (UTC)

good answers but i wanna to ask what changes does occur in effected parts so as to feel us itch?what happens at molecular level? which hormones or anything does trigger itching? —Preceding unsigned comment added by Myownid420 (talk • contribs) 10:33, 31 January 2010 (UTC)

Our itch article mentions opioids and histamine. This paper implicates MRGPRX1 in the peripheral nervous system. This paper implicates gastrin-releasing peptide as a mediator in the spinal cord. --Mark PEA (talk) 11:57, 31 January 2010 (UTC)

Not too long ago the 'Ask the Experts' section of Scientific American dealt with a question like the one you ask, although I don't remember the details or how many months ago it might have been. If I remember slightly right, it had something to do with certain skin cells themselves doing something like raising a false alarm or ? (I can't remember) I believe that article might answer your question though, even if I cannot personally link you to it. --Neptunerover (talk) 12:56, 31 January 2010 (UTC)

That gets into the area of autoimmune/allergic reactions. Some of the problem is at the skin, but I also think the brain has certain thresholds for how many nerves in an area need to report an itch before it takes it seriously. That's why, if you see a bunch of spiders, you suddenly feel itchy. The trigger threshold has just been lowered, and your brain now interprets every stray nerve impulse from the skin as a potential spider crawling on you. (I wonder how many of you will get itchy just from reading this. :-) ). StuRat (talk) 18:37, 31 January 2010 (UTC)

So you're saying it is possible to manipulate the itch trigger threshold of other individuals with words and images? So then when we go to a scary movie, they're manipulating a bunch of different triggers in our minds, like the shiver trigger, which gets her to accept an arm over her shoulders, and then next there's an itch trigger and she goes yuck and pushes your arm off her. It's all a clever plan by the film company to keep us coming back. =)--Neptunerover (talk) 00:20, 1 February 2010 (UTC)

What does Buddhism have to do with this? There are so many possible causes of itching that it is difficult to determine a cause but we are not allowed to provide a diagnosis. However allergies are another common cause but the wide range of allergies is anything from dust to temperature. ~AH1^(TCU) 03:10, 1 February 2010 (UTC)

Buddhist monks wear loose fitting clothing, though I'm not sure if this reduces any itching other than that which might be incurred through the wearing of tight clothing. Sometimes curing itching can be as simple as slipping out of that wool sweater. --Neptunerover (talk) 04:40, 1 February 2010 (UTC)

Saline Faraday cage

Would wrapping an object in two thin layers of plastic with salt water in between act similarly to the traditional metal Faraday cage? Horselover Frost (talk · edits) 04:40, 30 January 2010 (UTC)

The Electrical conductivity article shows the conductivity of copper to be ten million times that of seawater. So your saline bubble would be better than nothing, but very feeble. If it's transparency that you're after, then perhaps one of those transparent metal oxides like tin oxide would be better. --Heron (talk) 09:43, 30 January 2010 (UTC)

The conductivity of those tin oxides is worse even than salty water. But a Faraday cage only needs to be a mesh of wires - not a solid sphere - so it's easy to build one you can see out of if transparency is the problem here. SteveBaker (talk) 19:37, 30 January 2010 (UTC)

Flexibility is the issue, not transparency. Horselover Frost (talk · edits) 21:04, 30 January 2010 (UTC)

A wire mesh would be reasonably flexible. --Tango (talk) 21:16, 30 January 2010 (UTC)

Is the electric field static? If so, then there's no difference between a bad conductor and a good one: the electrical conductivity relates the E-field to the current density and, of course, there is none. The charge distribution inside the liquid cage material would be different from the metal one, as in the latter case the positive ions are fixed in crystal lattices. However, the macroscopic effect onto the E-fields must be the same: the cage has still to be an equipotential surface. In electrodynamics, you'll need to consider both conductivity and inductance, in addition to the usual refraction and reflection depending on the dispersion properties of the material. — Pt _(T) 01:09, 31 January 2010 (UTC)

You will have to consider the skin depth. In salt water is is much bigger, meaning that radio waves will propagate further through salt water. A mm of copper will be equivalent to 3 meters of salt water. (if we believe the figures above. Graeme Bartlett (talk) 11:03, 31 January 2010 (UTC)

touch screen

how the implement the touch screen system on the simple (used button)i-pod. —Preceding unsigned comment added by 117.242.97.71 (talk) 08:45, 30 January 2010 (UTC) if it's possible than send the brife explenation about it also inform that what is needed instead of the indium tin oxide —Preceding unsigned comment added by 117.242.97.63 (talk) 08:49, 30 January 2010 (UTC)

I am not an expert on Apple or iPods, however this section in the Touch screen article might answer your first question, Technologies /Capacitive/ Projected capacitance, at least for the iPhone and iPod Touch. Or specifically iPod click wheel. There is also iPod Classic. If this is wrong please let us know.
The second question, "what is needed instead of the indium tin oxide", needs a bit more detail if you can, please, for a faster answer. --220.101.28.25 (talk) 09:58, 30 January 2010 (UTC)

Adding to above re indium tin oxide quoting the Touch Screen article mentioned. "A capacitive touchscreen panel consists of an insulator such as glass, coated with a transparent conductor such as indium tin oxide", which also has its own article. --220.101.28.25 (talk) 10:15, 30 January 2010 (UTC)

super-simple question about life on other universe

this is a super-simple question, I'd just like to hear your answer explicitly. If we imagine a universe with different physical laws (as is commonly done) then let's imagine intelligent life in that universe, doing mathematics. When exploring the SAME closed axiomatic system (e.g. ZFC), would the life find the SAME theorems are true/provable as we do for the same system? For example, would the life find that in that universe (despite there being different physical laws), there are still infinite primes, and in every other way as well the mathematics corresponds to the mathematics here.

Don't tell me I'm being naive or failing to understand the difference between math and science: YOU'RE being disingenuous for failing to answer my simple yes or no question. It's a simple question. It's not a false dichotomy. Please just answer either,

“ yes, different physical laws, but if they support life, the life would find the same things true when exploring the same given axiomatic math - e.g. the life would find there are infinite primes, pi is about 3.14159..., and everything else we find in standard math, etc" ”

or you can answer

“ no, different physical laws for the universe might include different epistemology. We have no way of knowing that they will find the same theorems true/provable/etc even when exploring the same given closed math system ”

it's such a simple question. Just answer it honestly and directly for me please: will math and logic be the same. thanks! 84.153.213.154 (talk) 10:02, 30 January 2010 (UTC)

Tweaking constants is different from altering the working of logic, I think. (I don't know what altering logic would mean.) That is to say, "yes". 213.122.17.205 (talk) 12:39, 30 January 2010 (UTC)

In the future, please give us a chance to answer your question before assuming that we won't do so properly. Physics is separate from logic. We can easily conceive of different physical constants and even altogether different physical laws, but I certainly can't conceive of what it would mean to change logic. Since I can't conceive it, I can't say it is impossible, but the usual changes people discuss (what would happen if space was 4D? What would happen if the speed of light was 30mph? etc.) wouldn't have any affect on logic. They would, however, affect which axioms mathematicians would choose (and get funding!) to study. --Tango (talk) 12:58, 30 January 2010 (UTC)

sorry, does that mean "yes" or "no"? It seems, if I'm parsing your sentence correctly, that you're saying "since I can't conceive of the 'no' alternative, I can't say 'no' is impossible"? But wouldn't "I can't conceive of it" mean that it's absurd, and not a possibility? Surely if it were possible, you could conceive of it? 84.153.213.154 (talk) 13:19, 30 January 2010 (UTC)

It means "maybe". As I said, the kind of changes people usually talk about, which involve changing physical constants, wouldn't have any impact on logic (so the same axioms would give the same theorems). That doesn't mean that there aren't other changes possible (for an appropriate definition of "possible") that would affect logic. I am flattered that you think I am capable of conceiving everything possible, but I am not sufficiently arrogant to assume that. --Tango (talk) 14:24, 30 January 2010 (UTC)

I was going to answer the question but the OP needs to learn some manners —Preceding unsigned comment added by 94.171.225.236 (talk) 13:13, 30 January 2010 (UTC)

I'm sorry about my manner of posing the question here, but as you can see even despite my explicit request not to, Tango still felt the need to answer "physics is separate from logic" (I had said: "Don't tell me I'm being naive or failing to understand the difference between math and science") -- I literally meant that I understand physics and math are separate, please don't tell me that, try to understand what my actual question is instead. So, if I came off as rude, it is because I knew what the "knee-jerk" response is -- and I've gotten in dozens of times -- and tried to make clear that it isn't what I was looking for. If the honest answer to the question I am looking to have answered is "I don't know", you can say so. You don't have to pretend it's not a real question, or just ignore it, or come up with some other excuse not to answer it. 84.153.213.154 (talk) 13:19, 30 January 2010 (UTC)

In imaginary, hypothetical universes, anything can be anything - black is east, up is white. So, the original question is malformed. You're asking us if something hypothetical is possible. Really, you should be asking us what consequences there would be, given some hypothetical set of conditions. Unfortunately, we can't do that, because you haven't established exactly what conditions would be preserved in your hypothetical universe, and what would be different. Nimur (talk) 14:13, 30 January 2010 (UTC)

People are right to complain about your lack of manners. You cannot both ask a question AND tell people what the appropriate answer is at the same time. Dauto (talk) 15:03, 30 January 2010 (UTC)

Feel free to modify the question on my behalf so it is more clear. It's not that I want to tell people how to answer my question: it's that I want to make sure that it is clear that I am not conflating mathematics and physics. Thus the reason for my heavy-handed additions is only to make clear what my question is, since every time I ask it, I get an answer to a question that isn't mine. Thanks for any improvements you can make to the tone of my question while retaining its clarity. 84.153.213.154 (talk) 15:23, 30 January 2010 (UTC)

If I'm reading this right, you're asking someone to be polite for you? Vimescarrot (talk) 15:56, 30 January 2010 (UTC)

Even in this universe, with these physical laws, we've come up with different types of logic, and weird geometries. Any sort of logic or math is essentially a human construction (maybe we could generalize that to an intelligent construction), even if it was initially created to attempt to mirror reality. So perhaps the classical logic in this other universe would be different, and they might develop different systems of mathematics than we have. However, if this other intelligence did create a system that has the same structure as our numbering system, and the logic of proof was the same, then of course the same things would be true in it. Buddy431 (talk) 16:19, 30 January 2010 (UTC)

In this system, base 10 comes naturally to our intelligence because it's a base 10 star system. 9 planets and the Sun. Pluto's 'status' as a planet comes not into question considering that the Sun is 10, and counting down through the planets, Pluto is down around zero, and so the whole status as a planet thing is quite understandable yet irrelevant to our base 10 system. --Neptunerover (talk) 18:01, 30 January 2010 (UTC)

Please tell me you are joking... --Tango (talk) 18:04, 30 January 2010 (UTC)

How would I know? I've never checked any other stellar systems to see if the intelligence there uses a number base system coinciding with their number of planets plus stars, fingers, toes, or whatever else. Who knows? --Neptunerover (talk) 18:33, 30 January 2010 (UTC)

Please read correlation-causation fallacy. You can pick any arbitrary constant and say that "caused" the base numbering system, but you need some evidence to back it up (and SteveBaker below has shown the evidence against this hypothesis). In fact you mentioned another constant in your post, number of digits on both hands. You could also say that its the average weight (in lbs) of a 1 month old baby, average height (in cm) of a 4-year old, upper length of a chloroplast (in μm), ad infinitum. --Mark PEA (talk) 20:53, 30 January 2010 (UTC)

By George, I think you're right! Causation is strongly correlated with coincidence. --Neptunerover (talk) 21:44, 30 January 2010 (UTC)

NeptuneRover - that's incredibly stupid even by your standards. Humans learned to count when we only knew about the Earth, the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn. That's 8 - except that they wouldn't have counted the Earth because nobody knew it was a planet - so more likely seven. The other planets and moons require a telescope to see them and we're 100% sure that counting was discovered before lens-making. But even then - the planets mostly look very different from the sun and moon because you can't really tell there is a disk there with the naked eye - they were assumed to be stars that "wandered" rather than traversing the sky in nice circles. So why would they include the sun and moon, the wandering stars (but not the stationary ones), not include the occasional comet and also include this big seemingly flat thing that we happen to be standing on! There is no way that counting the planets (either with or without Pluto) determined our counting system...it's utterly obvious that it's the number of fingers that did that. Please don't answer questions by guessing or imposing your own (exceedingly weird) cosmologies. SteveBaker (talk) 19:25, 30 January 2010 (UTC)

Pardon me, sorry no, I'm afraid you misunderstood me there. I wasn't at all making a claim about causation. I mean, for instance, nobody knew Neptune was blue like an ocean prior to it's being named after a god of the sea, but that's not going to keep me from pointing it out as a coincidence. As far as what the coincidence means, if anything beyond nothing, who knows? Beyond the fact that such coincidences occur in vast numbers... Vast. --Neptunerover (talk) 22:35, 30 January 2010 (UTC)

Firstly, you said "base 10 comes naturally to our intelligence because it's a base 10 star system" - which is certainly a claim about causation. Anyway - what about Eris - that makes 11 and what about Makemake and Sedna doesn't that make it 13? So it's not even a coincidence - it's a contrivance of your own making added here just so you have something to say...it's like "OMFG! Both the 2009 Audi S6 Sedan AND the 2009 BMW M5 Sedan have 10 cylinders and we count up to ten. Coincidences are everywhere!" SteveBaker (talk) 23:05, 30 January 2010 (UTC)

(And they're both German automobiles! Will the coincidences never end?) Again you misunderstand about the 'causation' implied by my statement. I'm saying because it's a base 10 system, that comes naturally to the intelligence of this system. One doesn't cause the other, they only coincide. In this system, base 10 is a factor as basic as gravity, and life here has adapted to it. I don't want to argue here. --Neptunerover (talk) 23:36, 30 January 2010 (UTC)

Please - stop with this nonsense. "In this system, base 10 is a factor as basic as gravity, and life here has adapted to it." - no it's not! Octupi have 8 arms, not 10 - there aren't 10 planets, there are 8 or 13 or about 20 depending on how you count them. 10 is no more "basic" than a bunch of other numbers. I routinely do arithmetic in base 2, 3, 4, 8 and 16 - and on occasion 36 and 50. The human brain is just as capable of doing that as working in base 10. Also, there have been entire civilisations of humans who based their number systems on base 6 and 60. Your position is quite indefensible. Oh - and your "just so" story about Neptune is wrong too. The planet was not named until several years after it's discovery. People had measured the size of the disk of the planet before it was named - so it's color would have been well known by then. If you aren't prepared to defend your statements here (preferably with references) then don't post them. We really aren't interested in you posting your crazy pseudo-science here at the reference desk. SteveBaker (talk) 23:55, 30 January 2010 (UTC)

I don't want to argue. You do. I don't. Coincidentally, that's really weird that you mentioned octopi, since that's just like that Chuck Norris movie. Maybe there's a deeper meaning to everything after all. --Neptunerover (talk) 09:18, 31 January 2010 (UTC)

The preferred plural of "octopus" is "octopuses". --Tango (talk) 10:04, 31 January 2010 (UTC)

Yeah, well that may be preferred, but I heard the best one was "Octopods". --Neptunerover (talk) 12:33, 31 January 2010 (UTC)

Close - you mean "octopodes". That is what it would be if we were speaking Ancient Greek, but we're not, we're speaking English. English only uses certain foreign plurals with loanwords, everything else gets a normal English plural, and "odes" isn't one of the ones we use. --Tango (talk) 13:00, 31 January 2010 (UTC)

Hey right, that's what I heard! --Neptunerover (talk) 19:34, 31 January 2010 (UTC)

I believe, original poster, that you are caught up in too many concepts about laws and constrictions about the world. In your head, you appear to have reified so-called physical laws. They are just helpful approximations. It's easy to forget that, when those approximations are often so accurate and so useful. There never was and never will be a physical law per se. Vranak (talk) 18:20, 30 January 2010 (UTC)

Obviously the underlying truth in mathematics would be the same everywhere - but it's very likely that their math would be hard for us to recognize. For example:

• We say that the area of a circle is A = pi.r². We use the radius-squared to calculate the area with a constant factor of around 3.14159 that we call 'pi'. But in a different culture, it's possible that people might more routinely think about the areas of things and more often calculate the radius given the area - so they'd have r = wi.A^-2 - where 'wi' is short for 'wibble' and this is a fundamental constant which would show up all over their mathematics. Of course the value of 'wi' is approximately 0.318309 - which is 1/pi. They might even have come up with r = (wi.A)^-2 with 'wi' being roughly equal to 0.10132. The resulting contortions of our standard equations to keep them looking nice and simple with 'wi' instead of 'pi' would result in some different-looking equations.
• They might also choose to change the value of their units to make some constants equal to 1.0 so that they'd disappear from their equations altogether. If they chose their units of time and distance such that the speed of light were 1.0 then E=m.c² would become E=m and if they figured that out much sooner than we did in their scientific history then perhaps the whole idea that mass and energy are different would never exist for them.
• Another possibility is that their counting system might be different. We use digits that go from 0..9 (if we're working in base 10) - it's more than likely they'd be using some other counting base - which is a trivial matter to sort out. But there are other quite different choices: There is something to be said for using digits that mean -5 to +4. If I use small digits to mean 'negative', then you'd count in base 10 like this: 1, 2, 3, 4, 15, 14, 13, 12, 11, 10, 11, 12, 13, 14, 25... and then later: 44, 155, 154. There are actually some arithmetic simplifications that come from counting that way. You could imagine some weird setup where they preferred to keep everything in the log domain - so instead of doing simple counting with integers, they always used logarithms of numbers. IMHO, that's really unlikely - but using negative-valued digits actually makes a lot more sense than the way we do it. If you think that's unlikely - consider the Romans. Roman numerals are really a completely different way of representing numbers and would be a perfectly valid way to do arithmetic if it were not so horrible to deal with!
• Yet another weirdness could come about from their choice of what things are 'base units' and what are 'derived'. We have mass, length and time that we consider to be base units - but those are not the only choices. You can build an entirely self-consistent math and physics from choosing your base units to be something like speed, density and gravitational attraction. (Do I have that right? I think I do. Someone correct me please!)
• Most of our mathematics started out with geometry and arithmetic with things like set theory and topology coming much later. But if the aliens started out thinking about topology and set theory first and only got into arithmetic and geometry much, much later, then they would have discovered things in a very different order than we did and have a completely different take on how things tick. Beings that thought about math so differently might be spectacularly difficult to communicate with.

But none of those things make the fundamental knowledge any different - they would just serve to make their equations really hard to compare with our own. Any halfway decent mathematician could unravel them in short order - and then it would be childs play to write computer programs to translate their math and physics into forms that we'd recognize and vice-versa. SteveBaker (talk) 19:03, 30 January 2010 (UTC)

For more information about Steve's weird number system with negative digits, see balanced ternary (that's the base 3 version, but it's the same principle). I can't help with the base units thing because I have no idea what "gravitation attraction" means in this context... --Tango (talk) 19:30, 30 January 2010 (UTC)

Yes - I've come across balanced ternary - it's used in some telecoms applications. The nice thing about the scheme I described above is that if you're adding up a long column of numbers, you can just cross out matching pairs of (for example) 4's and 4's before you start adding. If the numbers are fairly random then in a long column, they tend to cancel out and you end up with very little actual addition and carry-one stuff to do in your head. Negative numbers are also easier to deal with because you don't need a '-' symbol, negative numbers just happen to start with one of the negative digits. Doing things like -7+3 in our system is painful - but 13+3 is easy 3+3=14 the 1 and the 1 cancel so the answer is 4 (or -4 in our notation). Subtraction in this scheme entails changing all of the big digits into little ones and then doing addition - there are no special rules for that...but there is a problem with 5 because there is no positive 5 digit - only a negative 5. This is why this system is most tempting to use it with odd-numbered bases. If you're doing (say) base 9 - then you don't need the ugliness of the '5' digit that has to be either positive or negative and which messes up the 'cancelling out' method of adding long tables of numbers because you end up with a bunch of left-over 5's that you have to tally up at the end. With a zero and 1,2,3,4,-4,-3,-2,-1, it's simpler to do base-9 arithmetic than base 10. SteveBaker (talk) 20:11, 30 January 2010 (UTC)

As a point of interest, Roman numerals are indeed horrible for doing written arithmetic in the algorism style, but are very well suited to arithmetic using an abacus. The Romans had handy little pocket abacuses, and you can perform quite sophisticated arithmetic using grooves in sand and pebbles. I thoroughly recommend a little research and experiment on the topic to anyone interested in history or maths. 86.180.52.43 (talk) 19:30, 30 January 2010 (UTC)

Steve, you might want to double check your calculations after the first bullet. Dauto (talk) 19:44, 30 January 2010 (UTC)

Yes - I did...sorry. SteveBaker (talk) 22:57, 30 January 2010 (UTC)

OP, one statement of yours needs to be strongly challenged: Surely if it were possible, you could conceive of it?. That assumes that all humans have the same imaginative capacity (er, no, 1000 times no), and that all humans know exactly what is possible and what is not (er, again, no; we're not pre-programmed robots; and we're not God). -- Jack of Oz ... speak! ... 23:42, 30 January 2010 (UTC)

Well, no, it was directed at me, so really it just assumes that I am perfect. That is an understandable mistake! ;) --Tango (talk) 10:06, 31 January 2010 (UTC)

Wow, what's with all the random spontaneous assumptions of psycholinguistics? This post is becoming chaos. Therefore, a healthy dose of oneness is required. ~AH1^(TCU) 02:55, 1 February 2010 (UTC)

why are winter winds so strong?

My daughter asked me this the other day and I had no answer, and it's actually a bit counter-intuitive. Since there is less solar radiation in the winter part of the globe, and hence less energy in the atmosphere, why does the wind seem to be stronger? --SB_Johnny | ^talk 12:35, 30 January 2010 (UTC)

"it's hurrying up due to the cold." is what I would tell her. 84.153.213.154 (talk) 12:51, 30 January 2010 (UTC)

Humor aside, why would you intentionally supply unscientific responses to a child's strictly scientific question? That is exactly the sort of diluted, nonsensical answer which discourages scientific approaches to everyday life. As for the original question, first you need to establish the fact that winter winds are stronger - which is verifiable. You can get data on average wind speeds in your region from the National Weather Service, this data table summary seems like a good place to start. The breakdown is regional and seasonal. Next, you can actually analyze the data (either by direct observation, or maybe run it through Excel and create a few basic graphs).

Now that we have some data to back up the claim, we can develop an explanation for the established trend - are the winter months windier, on average? After looking at the data some more, it seems that on average, winter months have about 2 mph stronger winds, across the USA. Keep in mind that this is a very simplistic average, and doesn't take into account things like gusts, duration, etc. More data is available on that here, also from NOAA's climate center. This trend must be related to the way that winds work - wind explains the mechanism that causes air currents to flow. I would have thought that the thermal gradients that cause winds are probably stronger during the summer months, because more incident solar radiation occurs during the day. But heating of air masses depends on more than just incoming solar energy - it varies a lot on your region and proximity to oceans, mountains, and so forth. The thermal gradients that cause wind are apparently actually stronger in winter. I'm actually having a bit of a tough time coming up with a concise, simple explanation - as the OP points out, less incident solar radiation intuitively suggests less total energy - but this is counter to the data. We can always resort to the "chaos theory" explanation of climate - that global-sized convection problems simply don't behave intuitively because they are so strongly coupled. Another way to look at it is that wind is caused by strong thermal gradient, not necessarily by large absolute values of temperature. It's possible that winter's lower insolation levels result in more uneven heating. Presumably, the lower the sun is in the sky, the more shadowed regions there are behind large hills and mountains - this could account for some small-scale uneven heating effects. I doubt this effect alone accounts for the net increase in wind speed during winter. Nimur (talk) 13:23, 30 January 2010 (UTC)

Winter means a higher thermal gradient overall between pole and equator. I believe this is relevant (source: half-remembered talk by climatologist). Algebraist 14:07, 30 January 2010 (UTC)

Is the wind stronger, or just colder? We probably notice a cold wind more than a warm one. You certainly do get strong winds in the summer - hurricanes are typically a summer phenomenon. --Tango (talk) 13:02, 30 January 2010 (UTC)

Yes, the average wind speed is higher during the winter and Algebrist has pointed out the correct reason: Stronger thermal gradient between the equator and the poles. Dauto (talk) 14:56, 30 January 2010 (UTC)

The point about hurricanes and tornadoes is an interesting, one, though. Are average wind speeds still higher in the winter if those type of extreme summer storms are included in the analysis ? If not, perhaps winds are just more evenly distributed in winter. Also note that most of the wind from a hurricane occurs over water, and observations of wind speed over water may not be included in the comparison. StuRat (talk) 18:04, 30 January 2010 (UTC)

Here is the actual answer as I understand it. In each hemisphere there is a transition zone between the polar and temperate regions that almost always contains a band of cyclonic storms that migrate generally from west to east, following what is called the storm track, closely related to the polar jet stream. In the winter (in the northern hemisphere) the storm track shifts to the south. Farther north, in the neighborhood of the Aleutian islands or the north of Scotland, you can get those sorts of howling storms at any time of year. For an explanation of the energy source, see Atmospheric circulation#Ferrel cellLooie496 (talk) 18:58, 30 January 2010 (UTC)

Another factor, in addition to those mentioned, as to why the winds *seem* stronger is the lack of leaves on the trees (if you're in a location where such things happen). The leaves act as a windbreak, tempering the gusts by inducing turbulence. Lose the leaves, and it is much easier for gusts to pass through the trees, making a location which would have been sheltered from the wind in the summer more open. It's why farmers on the plains plant evergreens around their farmhouses - since they don't lose their leaves in the winter, they temper the winds better than deciduous trees. -- 174.21.224.109 (talk) 20:00, 30 January 2010 (UTC)

Also, the recent storms in the northern hemisphere winter may be the result of the "Arctic Dipole": the warming in the Arctic reduces the overall temperature gradient, allowing the jet stream to sink farther south over land due to a strong negative Arctic oscillation, and those storms typically have strong winds, especially when cold arctic air collides with warm tropical air. This is often the cause of tornadoes as well, when in spring in the US and in early summer in eastern Canada different air masses collide. In summer and autumn is when the hurricane season occurs in the Atlantic, because there's more warmer air in the tropics that the storms feed upon. Extratropical cyclones at mid-latitudes clash warm and cold air, and the strongest winds are often located along fronts because that's where the air masses collide. ~AH1^(TCU) 02:48, 1 February 2010 (UTC)

Clouds id

Hello, I have a picture of clouds and i was hoping someone could help id the different kinds pictured. I think the picture was taken around 30000ft --Muhammad(talk) 14:26, 30 January 2010 (UTC)

Those appear to be a mix of cumulus clouds (the puffy 'cotton ball' clouds in the middle of the picture and below) and cirrus clouds (the thready ones at the top). go to cloud and see. --Ludwigs2 15:38, 30 January 2010 (UTC)

So its cirrus in the background, cumulus in the mid-ground. What about the large extensive ones in the foreground? --Muhammad(talk) 15:49, 30 January 2010 (UTC)

Have a look at the The Cloud Appreciation Society website[10]. Alansplodge (talk) 15:55, 30 January 2010 (UTC)

For Wikipedia articles please see Cloud, which has links to articles on all categories of cloud ie Cumulus, Cirrus as mentioned. The foregound clouds may be Stratus or Nimbostratus, seen from on top. --220.101.28.25 (talk) 16:21, 30 January 2010 (UTC)

moles

i am not talking about rodents.why do we have that black spots(that we mostly use as a identifying characteristic) on our body? many a times they are big, many a times small., sometimes just a spot WHY? —Preceding unsigned comment added by Myownid420 (talk • contribs) 16:47, 30 January 2010 (UTC)

This is a pretty big question which covers an awful lot of ground. I recommend our article melanocytic nevus, which is an overview of the types and causes of moles. TenOfAllTrades(talk) 16:59, 30 January 2010 (UTC)

Also you may like to note that moles are not rodents.--Shantavira|^{feed me} 17:10, 30 January 2010 (UTC)

The OP said they were not talking about rodents. They might not want to talk about rodents. --Neptunerover (talk) 17:48, 30 January 2010 (UTC)
Not meaning to assume anything about the OP with my previous comment, but one can never be too careful. Some people are scared of rodents. Ever see or read 1984? One avoids mentioning rats when around Winston Smith. --Neptunerover (talk) 18:55, 30 January 2010 (UTC)

Suffice to say they are not a good indicator of health. I've had moles go away. I can surmise they are the body's way of dealing with an excess or imbalance of something. Vranak (talk) 18:12, 30 January 2010 (UTC)

Since we have access to good, thorough, detailed, heavily referenced articles on Wikipedia – not to mention a wealth of information on the broader internet – the original poster would be well-advised not to rely on (inaccurate) speculation. TenOfAllTrades(talk) 19:11, 30 January 2010 (UTC)

Speculation? So if I am to understand you, you believe that that moles and overall corporeal health have no conceivable relationship? Vranak (talk) 19:25, 30 January 2010 (UTC)

I can conceive of lots of things — but it would be much more useful if you provided sources and references rather than guesses. TenOfAllTrades(talk) 20:13, 30 January 2010 (UTC)

Well, you know, curiosity killed the cat, and looking around in the broader internet can turn up some serious garbage, with the accuracy thereof being a matter completely beside the point. --Neptunerover (talk) 19:40, 30 January 2010 (UTC)

That comment was completely beside the point. ~AH1^(TCU) 02:27, 1 February 2010 (UTC)

This is the science reference desk. Nobody thought you were talking about rodents. You should have clarified that you weren't referring to the Avagadro constant. — DanielLC 07:16, 1 February 2010 (UTC)

Furnace efficiency vs. exhaust gas temperature

To raise the efficiency of a gas furnace, you want to reduce the heat loss in the exhaust gas. I wonder how much the exhaust gas temperatures differ between an average efficiency furnace and a high efficiency one. Does anyone know what the typical exhaust gas temperatures are for gas furnaces rated at 80%, 90% and 95% AFUE? —Preceding unsigned comment added by 173.49.10.80 (talk) 17:58, 30 January 2010 (UTC)

I don't have a direct answer, but would like to mention that the problem with lowering the temp of the exhaust gasses is that they no longer rise out of the chimney if they're too cold. This problem could possibly be addressed by adding an electric exhaust fan. You could, therefore, get a higher efficiency furnance than is otherwise possible. I don't think this is common practice, though, since the cost of the electricity must be factored in and any failure in the electric fan would make the furnace dangerous to use. StuRat (talk) 20:26, 30 January 2010 (UTC)

High efficiency furnaces do indeed use power ventilation. (And StuRat, not only is this common, it's required for all new installations in the US.) The temperature is low enough that they use 3-4 inch PVC pipe for the exhaust, and you need a drain to collect the water condensate from the exhaust. (The PVC pipe exhaust is much cheaper than building a chimney in new construction.) The boiler I have (average 93%) is programmed to lower the flame if the exhaust ever goes over 215F (and shut off at 240). The exhaust temperature depends on how hot you heat the water running through it, it's about 20 to 40 degrees above it usually. If it's only a little cold, I program the water to run at 100F, going up to 180F when it's -20F outside. Usually it's at 120-140. At 180 degree water it's not very efficient going up to 98.6% at low water temperatures. See a chart here. (Mine actually does better than that chart, but it gives the general idea.) There are many kinds of high efficiency boilers. The best ones are called mod-con. Modulating, condensing. They measure the outside temperature and modulate (vary) the flame to give different water temperatures. The are called condensing because they extract the Enthalpy of condensation of water, condensing the steam in the exhaust back into water (which you need to remove with a drain). Ariel. (talk) 00:37, 31 January 2010 (UTC)

A further complication is that the exhaust gas has moisture in it, and if you cool it down this moisture will condense out. Why is this a problem? Well, for one thing you don't want moisture in a system that was designed for dry gases (it mucks up the flow, as well as potentially corroding things). So what about if you carefully designed it so that water would only condense after it had left the chimney? Well, at least in an industrial context, it's still a problem if clouds of steam are coming out of your chimney because people assume it is smoke polluting the environment. So you have to make sure that the vented exhaust gases are hot enough to keep water from condensing until it has dispersed. With these restrictions in place, it is indeed pretty standard to extract heat from the exhaust gas to use elsewhere. The actual temperature it is practical to use will depend on the conditions at the site (temperature, humidity) and what you're using the heat for. After all, if you're warming something from 102 C, you're not able to cool your gas to or below that. 86.180.52.43 (talk) 00:08, 31 January 2010 (UTC)

Actually all the new boilers in the US do in fact make clouds of steam at the exhaust, and the first time I saw it I thought there was a fire and contacted the owner, and he told me it's normal. Now I have one of those, and so do many people. I believe these boilers are also required in the UK. The design of the boilers is interesting - it's counter flow. The inlet for air is above the exhaust. This helps the water that condenses inside flow downward, since the air is blowing it down. It also means that the coolest exhaust temperatures (the ones at the top, i.e. farthest from the fire) are used to warm up the incoming (cold) air. This helps the energy efficiency by extracting the maximum amount of heat from the exhaust. They are all made of stainless steel or aluminum to avoid corrosion. The condensate is slightly acidic (from the dissolved CO2 and from sulfur in the fuel) and you need to deal with it properly. If you need to pump it you need a pump rated for it. In some jurisdictions you need to neutralize the acid with chunks of limestone or marble in a tube. But usually you can just dump it down a drain and it mixes with other water in the house (but avoid using a metal drain unless the water is diluted). Ariel. (talk) 00:47, 31 January 2010 (UTC)

Wouldn't the corrosive waste water be a problem if there isn't any other water flowing into the pipes ? I picture it sitting for hours in metal pipes until some more water flushes it out. So you'd need all PVC pipes, from the drain to the septic tank/sewer, I'd think. StuRat (talk) 01:48, 31 January 2010 (UTC)

Don't use it with a septic system, I think it would (might) kill the bacteria. Water doesn't just sit in your pipes, it flows out immediately (unless it's installed wrong, and even then any "pool points" would quickly fill up with gunk, and water would flow right over it). Normally you have other water usage in your house. It's only if you have a pipe that never gets any other water that it's a problem. Over years it will corrode and thin the pipe. (At least from what I heard.) Most pipes are also "lined" with oil and gunk and biofilm that protects them. And it's not that corrosive, it takes years to damage a metal pipe. Some installers just drill a hole in the floor of the basement, stick the pipe in there and leave it. (I think that's nuts, but it's done, I guess it just drains into the soil under the house.) Others will make a hole to the outside and let it flow there (but watch that it doesn't freeze and block up). Also, not all places that the same level of sulfur in the gas. I think without sulfur it's really not very corrosive. If your jurisdiction does not allow copper gas pipes (because the sulfur corrodes them), then make sure to use the neutralizer kit. Ariel. (talk) 02:22, 31 January 2010 (UTC)

Actually, water does just sit in properly designed pipes, in the u bends, which are necessary to prevent sewer gases from backing up into the house. Those would be the first places to corrode. I agree with you that dumping water under the foundation is nuts, as it may seep back into the basement, or, over time, carry away soil and undermine the foundation. StuRat (talk) 18:27, 31 January 2010 (UTC)

A man who was a much published heating system expert of the 1950's once told me that even then they could have designed furnaces of higher efficiency that the typical 80%, by simply increasing the heat exchange surface area, but the limiting factor was that exhaust gases must not condense in the chimney. The house I live in switched from a low efficiency coal furnace to a higher efficiency gas furnace in the 1950's, and the exhaust gases condensed in the masonry chimney, causing creosote to seep through the chimney and stain the interior wall of the house. The solution then was to install a stainless steel liner of smaller cross section, which was less porous to the condensate, but which more importantly had a higher exhaust velocity to carry the gases out before they condensed. A later generation higher efficiency furnace requires forced draft to get the exhaust out. Edison (talk) 04:59, 31 January 2010 (UTC)

Clothes Washer and Dryer

Why isn't there one machine that washes and dries clothes? It would be awesome if the same machine could do the dishes as well.... --Reticuli88 (talk) 19:47, 30 January 2010 (UTC)

There might have been one on the Jetsons. --Neptunerover (talk) 19:51, 30 January 2010 (UTC)

There is, sort of. There's a combination device that has a washer on top, then drops the clothes down into a dryer, below, once finished washing. Why not a single machine ? Well, holding water involves rubber seals that tend to fail when heated to dryer temps. I suppose some high temperture silicone seals might hold up, so it is possible, but just not financially viable. I imagine that such a device would cost more than a seperate washer and dryer would. Still, for space-critical situations, like in a cabin on a ship, it might be worth the additional cost. StuRat (talk) 20:18, 30 January 2010 (UTC)

Gee, I just googled for "combination washer/dryer" and found a number of them, although they're quite expensive and it's unclear how well they work. Looie496 (talk) 20:31, 30 January 2010 (UTC)

We've had washer/dryer combos before. They work fine, but there is more to go wrong with them so we've found them less reliable and have a straight washer now. --Tango (talk) 21:42, 30 January 2010 (UTC)

I wouldn't be surprised if there already is such a machine (minus the dishing capacity) used in the larger factory laundromats that contract with hotels and hospitals, etc. Big Machines, I'm betting.
Incidentally, the potentially life-threatening implications of such a machine (or a similar machine) were explored by Stephen King in his short story the Mangler, not meaning to scare the OP. :) --Neptunerover (talk) 20:43, 30 January 2010 (UTC)

Actually large factory laundromats, and hotels use Continuous batch washers (AKA tunnel washers, or screw washers) it's basically a long perforated Archimedes screw the slowly moves the clothes from one side to the other passing through the various rinse and soap stages. See [11]. Ariel. (talk) 00:58, 31 January 2010 (UTC)

Washer/Driers are really common in the UK - I've owned lots of them over the years. In the UK, we generally have smaller homes than most Americans and there isn't enough room to have both devices. So they make front-loading machines that can go under a kitchen countertop which combine washer, spin-drier and hot air drier in one unit. They aren't as cheap as two separate units - but when space is at a premium, they are definitely the way to go. You'd think they'd be convenient too because you don't have to pull all of that damp laundry out of the washer and put it into the drier. But sadly, every one of these machines that I've ever seen has about half the capacity when used as a drier compared to what it can wash as a washer. So you still have to stop the machine, take out half of the load, do a drying cycle then swap out that half of the load for the other half...so it ends up being more work than with separate units. Dishwashers are very different beasts though - you need totally different internal racks for supporting fragile china - you wouldn't want to spin them and at the bottom of the dishwasher there is a food disposal gizmo that grinds up and waste food before it gets washed into the drains. Worse still, you wouldn't want the nasty chemical residues from clothes washing getting mixed into the water that's going to wash things you're gonna eat off of. SteveBaker (talk) 22:51, 30 January 2010 (UTC)

Wow, the UK is very futuristic in many ways, much like Japan, only their future styles are very different from one another. --Neptunerover (talk) 23:07, 30 January 2010 (UTC)

Two points. First, when you transfer clothes from the washer to a separate dryer, you leave some water behind -- the washer drum is still moist. A combination unit has to extract that moisture. Second, when you transfer clothes from the washer to a separate dryer, you can start another load in the washer. So for anyone who has more than one load per washday, having separate appliances may take up more space but it saves time (unless the combination appliance is appreciably faster than the separate ones, but then it probably wouldn't do as good a job). --Anonymous, 03:05 UTC, January 31, 2010.

Good points, but note that the type of combo unit I described, where the washing drum drops the wash into a separate drying drum when done, could possibly have a load of wash and drying going simultaneously, if they set it up to do so. But, of course, it would need to have the dry clothes removed before it dropped the 2nd batch of wet ones into the dryer. Perhaps there could be an additional step where it drops clothes from the dryer into a basket, when done. StuRat (talk) 18:20, 31 January 2010 (UTC)

Wronger than wrong

Our article on Wronger than wrong quotes Isaac Asimov who said "When people thought the earth was flat, they were wrong. When people thought the earth was spherical, they were wrong. But if you think that thinking the earth is spherical is just as wrong as thinking the earth is flat, then your view is wronger than both of them put together." Maybe this is going over my head, but what part about the Earth being spherical is wrong? That it's not a perfect sphere? A Quest For Knowledge (talk) 19:54, 30 January 2010 (UTC)

It is an oblate spheroid - basically, it has a fattened midsection because at the equator, forces relating to its rotation cancel out some of the gravitational forces pulling it together. Awickert (talk) 19:57, 30 January 2010 (UTC)

And there are mountains and valleys (the equatorial bulge is bigger, though). --Tango (talk) 20:03, 30 January 2010 (UTC)

An oblate spheroid is a description for the shape of the earth that is less wrong than an sphere. a geoid would be an even less wrong one. Dauto (talk) 21:42, 30 January 2010 (UTC)

That is true over the oceans, but over land the geoid would be just as wrong as the spheroid or worse, because gravity is uncorrelated with topography. Awickert (talk) 07:54, 31 January 2010 (UTC)

Of course, the point of view stated there seems based on Mr. Shermer's perception of what Mr. Asimov meant when he made the statement. Mr. Shermer has a highly advanced skeptical intelligence. There are likely to be other ways of interpreting what the statement means --Neptunerover (talk) 20:19, 30 January 2010 (UTC)

I can't think of one... --Tango (talk) 20:52, 30 January 2010 (UTC)

I believe you. --Neptunerover (talk) 21:34, 30 January 2010 (UTC)

Context should clear this up: here's Asimov's article on the subject in which he states pretty clearly what he means by that statement. http://chem.tufts.edu/AnswersInScience/RelativityofWrong.htm —Preceding unsigned comment added by Wevets (talk • contribs) 21:43, 30 January 2010 (UTC)

Wow, thank you for that link. A great writer. --Neptunerover (talk) 22:44, 30 January 2010 (UTC)

Yes, Asimov's article makes for an interesting read. I updated our article to make Asimov's point more clear. A Quest For Knowledge (talk) 22:47, 30 January 2010 (UTC)

Ah, thanks everyone! A Quest For Knowledge (talk) 22:08, 30 January 2010 (UTC)

The most obvious point here is that the earth isn't a perfect sphere - but a rather more complex shape that doesn't really have a proper mathematical name (the WGS84 description is the nearest approximation to the mean-sea-level shape - ignoring mountains and valleys). Saying that the earth is flat would be a wildly incorrect statement. Saying that it's a sphere is very, very close to the truth. As someone here pointed out a while ago, the earth is closer to being a perfect sphere than is a standard competition billiard ball. (And it's true - I checked - the acceptable engineering tolerances accepted by the rules of billiards allows a ball that is less spherical than the earth to be used in competition). So saying that the earth is spherical isn't true - but it's more true than saying that a billiard ball is spherical! Sadly, saying that it's an oblate spheroid or a geoid or anything else isn't 100% true either. But saying that it's a sphere is certainly a lot less wrong than saying that it's flat. Arguing otherwise degenerates into a matter of the semantics of the word "Truth" and to whether that is a binary state or a continuum - which is a silly argument that gets us nowhere and is best left as something to keep philosophers in full employment.SteveBaker (talk) 22:41, 30 January 2010 (UTC)

Steve, did you read Asimov's article? He's got a great quote: "Nowadays, of course, we are taught that the flat-earth theory is wrong; that it is all wrong, terribly wrong, absolutely. But it isn't. The curvature of the earth is nearly 0 per mile, so that although the flat-earth theory is wrong, it happens to be nearly right. That's why the theory lasted so long." A Quest For Knowledge (talk) 22:50, 30 January 2010 (UTC)

So, from one point of view, it all depends on the observer. That fits. --Neptunerover (talk) 23:09, 30 January 2010 (UTC)

It's not that I didn't read it - I think Asimov was wrong - VERY wrong. An inability to measure the curvature is the least of the problems. For the earth to be flat, it would have to be infinite or have edges - neither of which are remotely close to being true. It's a matter of topology. If the earth was a spheroid 1 meter across or the size of Jupiter, it wouldn't be any closer to being flat. It's not just a matter of the precision of measurement or the degree of approximation. On the real earth - you can move off in some given direction and after going far enough, arrive back where you started. You couldn't do that if it were flat. You couldn't tile the surface of the earth with square tiles - but you could (in principle) do that if it were flat. That's really why there is a significant difference between how "wrong" the flat-earthers are compared to those people who think the world is spherical. The difference between an oblate spheroid earth and a true sphere are tiny (note the billiard ball comparison). But the difference compared to a flat earth is more than a mere measurement difference. Asimov is a great science fiction writer...but when he strays beyond that, I have less respect for what he says. SteveBaker (talk) 01:27, 31 January 2010 (UTC)

But to an ancient Summarian, an Earth that goes on forever or one curves around and returns to the same place after 40,000 km are the same. If your empire is a couple hundred miles across, it doesn't matter if what's beyond is infinite or not. And as Asimov pointed out, it was the curvature that clued people in on Earth's true nature, well before anyone had the means to sail around the world or try to tile the Earth with squares. If you agree with Asimov's basic premise (that believing the Earth is flat is more wrong than believing it's a sphere), I'm not sure what your beef with him is. Buddy431 (talk) 01:56, 31 January 2010 (UTC)

This is my favorite line: They felt it was flat on the basis of sound evidence. It was not just a matter of "That's how it looks," because the earth does not look flat. It looks chaotically bumpy, with hills, valleys, ravines, cliffs, and so on. So, if anyone ever tries to tell you the earth is flat, you tell them, "duh, look around you." --Neptunerover (talk) 23:16, 30 January 2010 (UTC)

Neptunerover: The Earth can't be flat. If it was, there wouldn't be 4 simultaneous days in one Earth day.[12] :) A Quest For Knowledge (talk) 23:28, 30 January 2010 (UTC)

Again with the time cube? Are you kidding me? That stuff is crap! --Neptunerover (talk) 08:40, 31 January 2010 (UTC)

Hahahaha! SteveBaker (talk) 01:27, 31 January 2010 (UTC)

New rule, AQFK: you're not allowed to post while I'm eating. I nearly choked! – ClockworkSoul 08:40, 31 January 2010 (UTC)

I believe the underlying philosophy of this quote goes something like this. Ideas are just ideas. Whether the ideas are factual or inaccurate, they are first and foremost just concepts that guide our perception of the world. So saying the Earth is flat in no way an impediment to sailing the oceans. We may gain a subtler understanding if we consider it as a sphere, but again, it's really just a mental heuristic whose merit lives and dies with how useful it is. So getting too wrapped up in the description of the Earth is wrong. If it's useful it's useful, but in any event the ideas are only meant to guide understanding, not be a rigid container for whatever is out there. Vranak (talk) 12:22, 31 January 2010 (UTC)

Excellent, very insightful; I may borrow some of your expressions. =) --Neptunerover (talk) 12:39, 31 January 2010 (UTC)

I think you've managed to totally miss the point of the last part of the quote! Putting it another way: All models are wrong to some degree. But if you think that gives all models the same truth status, then you have made a bigger error than the erroneous models themselves—some models are truer than others. --Mr.98 (talk) 13:30, 31 January 2010 (UTC)

I actually get the opposite sentiment from the quote. Treating other people's genuine understanding of the shape of the world as wrong is itself wrong. It's preferable to see the other person's point of view than to belligerently insist that only your model is correct. This is where Galileo got into trouble with the Church. Vranak (talk) 16:45, 31 January 2010 (UTC)

Very cool. I may be wrong, but you're wronger than me! No I'm not! Yes you are! (ad infinitum) The wrongest is he who point finger. (such competitions can be very heated) --Neptunerover (talk) 19:56, 31 January 2010 (UTC)

Exactly. Camaraderie is generally more valuable than being 'in the right'. Of course you have to uncompromising about the truth in certain applications, like aerospace engineering and bridge building. Vranak (talk) 16:53, 1 February 2010 (UTC)

This isn't just a pedagogic or philosophical nitpick. I know several geophysicists who run numerical simulations of things (climate, earthquakes, heat flow, and other earth processes). A fundamental assumption of these codes is a rectangular- or cubic- grid. In some cases, the computer simulations are performed in spherical coordinates - but more often than not, the error between a cartesian-grid ("square earth") and polar grid ("circular earth") is so negligible for a particular problem, that it's not even considered. So, even reputable scientists can often use the theoretical approximation of a "flat earth". These sorts of "egregious errors" are clearly counter to modern scientific understanding - and these scientists are by no means unaware that the earth is actually a mostly round object with a particular shape that can be mathematically described or numerically approximated. It's just not worth it. The point is that scientists need to be aware of all the assumptions they are making. The "relativity of wrongness" can be rephrased quantitatively as "the sequence or order in which each assumption breaks down as the problem parameters become more generalized." If a scientist is cognizant of that sequence, he or she knows when to stop trusting the results of a theory or simulation. The same can be said for any of a variety of theoretical simplifications - classical physics, laminar flow, ideal gas law, perfectly elastic collisions, pure substances, etc. Nimur (talk) 19:50, 31 January 2010 (UTC)

Perhaps this entire discussion could be attached on the talk page for wronger than wrong, not for use as any sort of original insight, but as a reference for what the article should consist of in order for all sides in the issue of wrongness to be represented and covered fairly in the article. --Neptunerover (talk) 23:28, 31 January 2010 (UTC)

Eratosthenes calculated that the Earth was round, and found a rather accurate diameter using a stick and the Sun's shadow. But science is always evolving, and paradigms shift. Scientific skepticism is useful for chosing more likely hypotheses, but may actually prevent science from progressing. There are computer models that depict climate and earthquakes, but is there any singular model that puts everything altogether? There are a countless number of interactions and co-interactions, and it is not possible to depict all of them. Climate models, for example, depict a rough smoothing of the averages over time, but what we experience are the extremes. Recently, a negative feedback was identified in water vapor in the lower stratosphere, and after 2000 a tipping point was passed, causing the stratospheric cooling to reduce water vapor content. Warmer water in the Central Eastern Pacific contributed to lower water vapor content and cooler lower stratospheric temperatures for the past decade. I noticed that Talk:Iris hypothesis has a discussion about this. Climate skeptics will use this to try and disprove global warming, but recent developments like this do not falsify the whole theory, because it's certainly possible that while CO2 and other greenhouse gases increase in the lower troposphere, more tipping points will be passed, and the rate of the increase in the intensity of the extremes increases.

Simplicification comes in many forms, for example a lie to children and discredited thought resulting in widespread scientific misconception such as the tongue map. ~AH1^(TCU) 02:12, 1 February 2010 (UTC)

The only paper ever published in a peer-reviewed scientific journal on Intelligent design

The FAQ on the talk page for our article on Intelligent design states "the only article published in a peer-reviewed scientific journal that made a case for intelligent design was quickly withdrawn by the publisher for having circumvented the journal's peer-review standards". Where can I find more information on how this paper was published and the reaction of the scientific community? It seems like it would be an interesting story. A Quest For Knowledge (talk) 20:51, 30 January 2010 (UTC)

If I'm not mistaken, you might be talking about Stephen Meyer's paper "The origin of biological information and the higher taxonomic categories" in Proceedings of the Biological Society of Washington.

A review of the controversy can be found here from the Palaeontological Association: http://www.palass.org/modules.php?name=palaeo&sec=newsletter&page=25

And here from Panda's Thumb: http://pandasthumb.org/archives/2004/08/meyers-hopeless-1.html

Those are not NPOV, but I'm going to leave finding the other side of the story from Intelligent Design Creationists as an exercise to the reader. Wevets (talk) 21:36, 30 January 2010 (UTC)

Wikipedia has an article on the specific issue: Sternberg peer review controversy. 98.228.57.197 (talk) 21:39, 30 January 2010 (UTC)

It really was a ridiculous matter. The journal in question is not one that publishes material like this at all. It normally publishes dry descriptions of newly discovered fossils of animals and plants and discusses where they fit into the established taxonomy...and nothing else. Then one day, the editor of the journal resigns to take up work in the areas supported by this article. That's fair enough - he has the right to do that. But AFTER resigning but BEFORE actually leaving his post with the journal, he causes this article to be published with himself as the sole reviewer and without the consent of any of the other editors in flagrant disregard for the subject area or publication rules of the journal.

I don't see how anyone could possibly consider that reasonable - no matter what the field of enquiry. It was a breach of the journals' publishing guidelines, it was a clear conflict of interest for the editor, it was a drastic change of direction for the subject matter of the journal undertaken by someone who had already resigned their position and who was merely acting as a 'caretaker' until a replacement editor could be recruited. It's hard to imagine a less appropriate way to get an article into a Journal...maybe if you forced them to print it at gunpoint or something?!? Anyway, the entire (remaining) staff of the journal has since repudiated the publication on grounds that it's publication peer-review rules were ignored. So to proclaim the status of that journal as backing up the claims of the article (which is what you mean when you claim that peer-reviewed publication actually means something) is really a lie.

Furthermore, the article did not actually make any claims either for or against ID - it was purely a "review article" - a not uncommon scientific practice of collecting together a lot of references on a particular subject and summarizing them in an article for the convenience of the readership. The article didn't present any direct evidence either for or against ID - it merely pointed out that a lot of (not-peer-reviewed) material had been published - and as such, I suppose, it was true.

So the bottom-line truth here is "Someone dishonestly published a not-peer-reviewed paper in a journal from an unrelated field that merely summarized existing not-peer-reviewed writings - and it was later repudiated by the journal." Great. Score one point for ID...or something. It speaks more for the dishonesty of the ID community that they uphold this as proof of the legitimacy of their field than it benefits them. In the end, getting a paper published only means something if the scientific community in general accept the status of the journal in which it was printed. Because the journal clearly repudiated the article - scientists are not going to be even slightly impressed by the fact of its pubication...and that's what matters for an idea to be taken seriously. SteveBaker (talk) 22:28, 30 January 2010 (UTC)

Question re: Magnetic pole switch

Since the Earth is due for a pole switch any time now, what are the likely effects it will have on computing equipment? Will every hard drive across the world get wiped? Should I backup my files on cd rom? —Preceding unsigned comment added by 82.43.89.14 (talk) 23:01, 30 January 2010 (UTC)

One thing up front... "any time now" is only true on geological time scales, if it is true at all (and as the article makes clear, it is not exactly clear that it is going to happen at all). So we're talking about maybe tomorrow, maybe another million years from now, maybe even more. So I'm not sure you need to worry about this as a short-term backup problem. You probably should back up important files on CD-ROM, in general, because the odds of your hard drive having a catastrophic collapse in the next year or two is much, much higher. The odds of every backup hard drive you have failing at the same time is probably higher than this pole shift happening in your lifetime.

A second thing. Let's imagine that this does happen tomorrow and it destroys, for some reason, all magnetic-based media. Whether your e-mail has been backed up is probably the least of your, or anyone else's, problems. There is really no way for your to plan for such a contingency and expect it to matter much. At least, not other than general pandemonium planning (potable water supplies, etc.).

I don't know what the effects would actually likely be, though, so maybe someone else can clear up on that. --Mr.98 (talk) 23:48, 30 January 2010 (UTC)

Direct effects will be zero. The earths magnetic field is so weak you would not notice. It will do nothing whatsoever to hard disks, floppies, etc. However, it might be weak, but it's also large. Indirect effect, specifically from solar wind could become a huge problem. It could induce voltage surges in powerlines that might burn up anything connected to them, or it might simply trip some breakers (this happened once before in canada on August 10, 1996). I don't think that radiation would be a problem, but I'm not sure. Radio transmission would almost certainly be hard if not impossible during (but not after) the switch. Please note, that all this is not from the magnetic field, but from solar wind, which the field is not blocking for us. Ariel. (talk) 00:14, 31 January 2010 (UTC)

Original poster: You realise the article you linked to, Cataclysmic pole shift hypothesis, refers to a change in the axis of rotation, and has nothing to do with Geomagnetic reversal...right? Vimescarrot (talk) 00:28, 31 January 2010 (UTC)

Note that the pole switch linked in the question is not simply a magnetic polarity reversal, but rather the Cataclysmic pole shift hypothesis, which is the extremely "fringe" idea that the Earth's axis of rotation sometimes changes cataclysmically. If something like that happened, the effects would be devastating on many levels. But it isn't going to happen. Even relating to a magnetic polarity reversal, though, my understanding is that the Earth's magnetic field protects us against cosmic radiation, so the collapse that would occur during the reversal might not be so innocuous even though the field itself is pretty weak. Looie496 (talk) 00:29, 31 January 2010 (UTC)

No Ozone layer or Van allen belt effects? Thought pole switch as supposed to be real BAD?? re radiation getting throught to Earths' surface? --220.101.28.25 (talk) 00:45, 31 January 2010 (UTC)

It could be bad, but it can't be too bad - it has happened many times before without any serious effects. We will still have an atmosphere to block radiation, so it will only be a small increase in radiations levels at the ground. --Tango (talk) 11:38, 31 January 2010 (UTC)

Also, I don't believe that the magnetic polarity reversal happens instantly, but over thousands of years. The first signs would be pockets of magnetic instability and reversal, and we do seem to have had some of those. The pockets would move around and slowly grow until eventually more area had the reverse polarity than the normal polarity. Of course, during this period the overall magnetic field is quite weak, allowing the solar wind to wreak havoc on the Earth. StuRat (talk) 01:24, 31 January 2010 (UTC)

The prediction that we are "due for one" is based on the average time between shifts in the past. But these aren't by any means regularly timed events - sometimes the planet goes for millions more years without one happening and other times they come in rapid succession. So it's not like there is a clock ticking down towards zero - then KAPOW!! It's more like you shuffle a deck of cards, draw one - if it's the six of diamonds, KAPOW!! If it's not, you reshuffle the cards and try again. The mechanism is complicated but the fact that we haven't had one for a long time doesn't appear to affect the probability that we'll have one today. I don't think hard drives are affected - the earth's magnetic field is really weak and the disk drives in your laptop don't go wrong if you pick it up and turn it upside-down...which (in effect) reverses the magnetic field from the perspective of your hard drive. SteveBaker (talk) 01:40, 31 January 2010 (UTC)

The biggest problems in terms of magnetism that I know of would be with navigation (both with animals and for humans), though I suppose humans are probably smart enough to see the SE on the compass and head North-West. Falconus^{p t c} 02:42, 31 January 2010 (UTC)

Or just use GPS. --Tango (talk) 11:38, 31 January 2010 (UTC)

Maybe not. The effects of the (temporary) disruption of our protection from charged particles streaming from the sun are hard to predict. It's very possible that such radiation would wipe the memories in our satellites and/or disrupt the radio waves they emit for our GPS receivers to pick up - or (worse still) disrupt radio commands controlling the satellites - resulting in yet more chaos. SteveBaker (talk) 16:30, 31 January 2010 (UTC)

Thank you User:Ariel. for the relevant and helpful answer. —Preceding unsigned comment added by 82.43.89.14 (talk) 11:22, 31 January 2010 (UTC)

Any cataclysmic effects are unlikely, but an extreme solar flare could suddenly put nearly half of all North Americans out of power. In addition, holes have been discovered in the Earth's magnetic "shield". If such a scenario as a strong solar flare directed at Earth does occur, then long power shortages are likely, making the 2003 blackout pale in comparison. [13][14]. ~AH1^(TCU) 01:14, 1 February 2010 (UTC)

The concise answer, I believe (I am not an expert) is that what we have to be worried about is not a reversed magnetic field, it's the time *between* when the poles are normal and when they are properly reversed. While the field is unstable, solar flares can barrage us with catastrophic magnetism. Of course as others have pointed out, you probably should be equally worried about the world-ending ice age that is coming 'any time now', the world-ending volcanic eruption in North America that is coming 'any time now', or the world-ending asteroid that is coming 'any time now... --Jmeden2000 (talk) 16:21, 1 February 2010 (UTC)

January 31

take a solution of enantiomerically pure lactic acid in water ... pH 4-5

The lactic acid will start racemising slowly, right, until an equilibrium is reached between the two isomers? How long will this take? Racemisation of chiral sugars seems pretty rapid -- so why does the optical purity of your lactic acid matter?

Or is it harder to racemise a carboxylic acid versus an aldehyde/ketone? The enol form seems stabilised by the alpha-hydroxy group though. I could imagine the hydroxy group becoming a carbonyl and carboxylic acid carbon bearing two hydroxy groups (as one of the tautomers). John Riemann Soong (talk) 00:00, 31 January 2010 (UTC)

Thinking about other things and performance in minesweeper while tired

I have noticed that, while tired, I get better times in 16x30 99 mines minesweeper when I'm thinking about other things. I would get 1:50 or a few seconds over two minutes most of the time, but when thoughts start to wander I hit 1:30 - 1:40, about the same as when in a state of full awareness. What's happening and could you name something similar? Are the events both effects or this there causality? Wild speculation is wished. --194.197.235.240 (talk) 02:21, 31 January 2010 (UTC)

Are you writing down the times for every single game you play? Otherwise it could be Confirmation bias or Illusory correlation. Ariel. (talk) 02:29, 31 January 2010 (UTC)

This is purely WP:OR but personally I find that my limiting factor at most points during a given game is my click speed rather than the rate I can process the information. My times are around where yours are (typically 85-110s). My level of concentration doesn't seem to make much difference (although I don't have any data to back that up). However when I try really hard to achieve fast click speed I tend to make more mistakes and it ends up slowing me down compared to when I'm "loose", including when I'm not paying attention. Many times that I've gotten a high score have been when I wasn't expecting it. As for tiredness, I do have data for time of day versus completion time, and I seem to do worst in the few hours after I wake up and then fairly steady for the rest of the day with a slight improvement late at night. Rckrone (talk) 03:56, 31 January 2010 (UTC)

(OR) I have noticed a similar effect when solving Sudoku puzzles and I attribute it to subconscious Pattern recognition (psychology). Cuddlyable3 (talk) 16:41, 31 January 2010 (UTC)

Yes, and I've noticed this effect in Minesweeper specifically. For example, if I have uncovered a "1" and one adjacent mine has already been marked, I can either consciously think that this means the other 7 squares must not have mines, or my subconscious can do that for me. Apparently, the subconscious is significantly faster at such tasks, and seems to take over more when the conscious mind is either fatigued or busy. I believe this is because the conscious only works on a single thought at a time, while the subconscious is capable of multiprocessing. As I write this, it's probably thinking about scratching that itch on my leg and several other things, all at once.

So, then, if the subconscious is actually faster at certain "no-brainer" tasks, perhaps we should think about how to use it more for such things. I've noticed that most of car driving seems to operate on a subconscious level, which is normally good, but can be bad when you mysteriously arrive at the wrong destination. Getting just the right mix of conscious and subconscious brain activity involved in every task is quite important, it seems to me, and significant research should be devoted to this topic. Thus, your seemingly trivial Q may give us a very important insight into an much bigger and more important Q. StuRat (talk) 18:08, 31 January 2010 (UTC)

It seems to me that the ability of the 'sweet spot' of human awareness to really focus on a task at hand is generally limited. There are other parts of our awareness that are paying better attention than us. This is evident to me when I can't find something that I set somewhere. As long as I consciously look and look for it, it's impossible to find. But then when I stop seeking it myself and let that part of me that knows right where it is show me where it is, all of a sudden I will realise I am looking right at it. --Neptunerover (talk) 20:26, 31 January 2010 (UTC)

I would even compare a human to the Starship Enterprise, where, while we might be the captain, we cannot keep track of everything going on around us. And so we have a crew too who monitor the sensors and alert us if there's need. The onboard computer keeps track of everything, and tapes can all be reviewed (memory). --Neptunerover (talk) 23:38, 31 January 2010 (UTC)

Sleep and creativity may be of interest. ~AH1^(TCU) 02:34, 1 February 2010 (UTC)

I asked a similar question last month, please see this discussion and the VERY useful external links provided therein:Wikipedia:Reference desk/Archives/Science/2009 December 18#Autonomous behaviour on Guitar Hero. Regards. Zunaid 12:54, 1 February 2010 (UTC)

No matter how much I eat, I don't gain weight.

Request for medical advice (and some highly irresponsible advice) removed. If you wish to debate this removal, please start a thread on the talk page - not here. SteveBaker (talk) 16:24, 31 January 2010 (UTC)

Polyethylene foam bed vs Urethane

breathing? —Preceding unsigned comment added by 67.246.254.35 (talk) 05:55, 31 January 2010 (UTC)

Breathing? --Neptunerover (talk) 09:09, 31 January 2010 (UTC)

BREATHING? --124.157.247.221 (talk) 09:40, 31 January 2010 (UTC)

Both of these polymers are watertight and impervious to air, you cannot breath through them. Whether they will suffocate you will depend on the structure, whether there are holes that connect. However a firm foam is likely to be closed cell. Graeme Bartlett (talk) 10:52, 31 January 2010 (UTC)

So then, Polyethylene foam bed vs Urethane: Not for breathing, no. --Neptunerover (talk) 11:06, 31 January 2010 (UTC)

i mean which will breathe better so i dont sweat —Preceding unsigned comment added by 67.246.254.35 (talk) 15:26, 31 January 2010 (UTC)

They could only stop you from sweating by keeping you cool...so the question becomes one of how to get the heat out. Maybe less bedclothes? SteveBaker (talk) 16:20, 31 January 2010 (UTC)

no —Preceding unsigned comment added by 67.246.254.35 (talk) 16:24, 31 January 2010 (UTC)

For breathing (porosity to air), try a feather bed, but if you want air to circulate below you, then perhaps just a wire mesh would be best, though not most comfortable. As Steve said, if you want to avoid sweating, just reduce the thermal insulation above you. Dbfirs 17:34, 31 January 2010 (UTC)

While keeping the body cool will limit the moisture released from the skin, it will not eliminate it. Thus, the circulation of air and/or absorption of moisture by the bedding material is important. Note, however, that the "bedding material" also includes the sheets and perhaps a "feather top", etc. Thus, the mattress itself may be completely impervious to water, so long as enough absorbent material is between it and the occupant. This might be a good way to do things, as a mattress may be ruined if someone has an "accident", while other bedding may be more washable. I myself use a comforter as a "bottom sheet" (although I haven't had an accident in several decades now :-) ). StuRat (talk) 17:48, 31 January 2010 (UTC)

We do not provide medical advice. However materials such as those mentioned and even nylon can cause overheating (this is how a sleeping bag works). Cotton does not restrict heat flow as much and therefore may have better air flow. ~AH1^(TCU) 00:57, 1 February 2010 (UTC)

Horrible Insects

Inspired by Red imported fire ant, what prevents an insect species from evolving that would prey on mammals, entering by the ears, feeding on the brain and using the scull as protection? 95.115.151.113 (talk) 15:05, 31 January 2010 (UTC)

Evolution is a slow, incremental process. You'd first have to imagine an insect that would be interested in clambering around inside a mammalian ear without somehow getting through the skull and into the brain - and then imagine incremental benefits to each step. Expect this change to take maybe a million years to happen. Bear in mind that the mammals in question will also be evolving ways to keep these pesky insects out of their ears in the meantime. It's not a simple matter. SteveBaker (talk) 16:19, 31 January 2010 (UTC)

The eggs of parasites are microscopic and can be passed sexually, through shaking hands, walking barefoot, from a pet, eating or drinking from someone else's glass, bottle, can, fork etc., swimming in polluted lakes, rivers or streams, going to the beach, etc. Entamoeba Histolytica[15] can get into the liver, the lungs and the brain. Cuddlyable3 (talk) 16:34, 31 January 2010 (UTC)

This would be catastrophic for whatever insect species decided to try to prey on mammals. We are thinking, feeling, revenging creatures that would, upon discovery of this new predation, seek out and destroy every nearby colony! Vranak (talk) 16:51, 31 January 2010 (UTC)

Um, no. Plenty of insects prey on living mammals—mosquitos and fleas being two obvious ones, not to mention all of the parasitic worms and larvae that would love to get inside us and burrow around. Even us mighty revenging, thinking human beings have been shown to have limited capacity to deter such activities (it has taken until the 20th century to even start to get a handle on the worst of such pests in the most developed parts of the world). And of course if we get beyond the mistake that "mammals" and "humans" are identical, there are even bug-sized creatures that eat small mammals, birds, and fish (army ants, certain large spiders). The issue, here, is that insects don't seem to outright hunt and kill large animals. The reason for this is probably both ecological (it would be a tremendous waste of biomass, and such an insect would probably deplete its food supply rather quickly) and evolutionary (it is evolutionary easier to feed on carrion than it is to try and hunt a big animal, when you are that small). --Mr.98 (talk) 19:24, 31 January 2010 (UTC)

Mmm, as I read the initial question, I inferred a sort of nightmarish glint about, well, horrible insects actively going after healthy individuals. Everything you point out is true of course, but these infestations are inevitability spawned out of disease. The prime mover is a lack of health, not hungry little insects. Vranak (talk) 22:10, 31 January 2010 (UTC)

Not true for botflies, an article I fond after posing the question. Guessing from the answers raising up every god and reason (like that a dog could make its paw scratch behind the ear-hole already inside the scull) to make believe this cannot happen, I must have hit some severe archetypical nightmare. 95.112.190.236 (talk) 17:43, 1 February 2010 (UTC)

I disagree that evolution has to be slow and incremental. When the barrier to selection is low, evolution is very, very, very rapid, like tossing water into a solution of acid chloride. A selection barrier is a bit like activation energy -- when high enough, it will prevent selection in a certain direction even though that direction may be favourable to the species and thus selection in that direction will be slow. John Riemann Soong (talk) 16:56, 31 January 2010 (UTC)

It wouldn't work. The inner ears are extremely sensitive, and if a bug gets in there (which happens occasionally), people will do whatever it takes to get it out, even if it means pushing sticks in and damaging sensitive tissues. There was an African explorer (Stanley?) who lost hearing in one ear due to an episode of that sort. Looie496 (talk) 17:02, 31 January 2010 (UTC)

What could a cow, a dog, a cat do to get such a bug out of the ear or at least kill it? 95.115.151.113 (talk) 17:24, 31 January 2010 (UTC)

A dog or cat could maybe get a claw in there and do some damage. As for cows, there are birds, like oxpeckers, which specialize in removing parasites from them. Also, animals would be under evolutionary pressure to develop a defense, like a thick, poisonous earwax. StuRat (talk) 17:38, 31 January 2010 (UTC)

The dog or cat would probably do more damage to themselves than the bug. They have limited ability to remove pests from themselves, even if they are bothered by them. Ear mites drive dogs crazy but there isn't much they can do other than shake and scratch ineffectively. The thing is, it is better for the mite to not be fatal—the affected dog then can spread more mites to other dogs, and so on, and the mite has plenty of food as it is (what would a mite do with a whole dog?). --Mr.98 (talk) 19:24, 31 January 2010 (UTC)

What provides the bugs/mites/critters with such wisdom? Imagine a mutant putting (nearly) all available resources into reproduction. A brain even as small as from a cat can provide large amounts of nutrients (yummy fat and proteins). Having more offspring is a primary trait in natural selection. As insects have far more generations than mammals do have in the same timespan, the mammals would not have enough time to adapt. Such a mutant would spread explosively, killing off their pray nearly entirely in a short time, than die out or establish an equilibrium with the more hardy and resistant specimens of their pray. Is there any evidence/hint that this ever happened in the history of live? 95.112.190.236 (talk) 17:09, 1 February 2010 (UTC)

There's some sort of cat disease that a large proportion of people are said to be infected with and includes cysts in your brain. 92.24.73.102 (talk) 21:43, 31 January 2010 (UTC)

Toxoplasmosis? --Dr Dima (talk) 22:48, 31 January 2010 (UTC)

There's also Baylisascaris sp., and Taenia solium. Note that these three are very different critters: Toxoplasma gondii is a protozoan, Baylisascaris is a roundworm (class Nematoda), and Taenia is a tapeworm (class Cestoda). None of them is an insect, though :) . The only insects I can think of that live in the relative safety of the mammalian skull are the fly larvae that live in the sinuses of the sheep. Their Latin name will come back to me in a moment. --Dr Dima (talk) 22:56, 31 January 2010 (UTC)

The sheep nasal bot-fly is Oestrus ovis. Nasty, nasty critter. We don't have an article on it, much to my surprise. --Dr Dima (talk) 23:07, 31 January 2010 (UTC)

However, we do have an article on the gnat in the Titus' brain (which Titus entirely deserved for what he did). Mysterious are the ways of the Editors. --Dr Dima (talk) 23:14, 31 January 2010 (UTC)

I saw a doco recently which would have been great to post here. It was of a herd of African cattle of some sort, they were all peacefully grazing, relatively still, except for their ears which were wildly gyrating, no doubt because of the insects, it actually made me laugh it looked a bit ridiculous. Even Darwin in Origin of Species recognised that insects play a not insignificant role in the success or failure of larger mammal species. He said even the small tail of the giraffe may seem superficially quite ridiculous and pointless to evolve but even if it provides a little relief as a swatter from the constant harassment of insects, it makes the animal more fit, not just less likely to be killed by insects, but being so worn down by them as to succumb to diseases or even other predators. Vespine (talk) 23:43, 31 January 2010 (UTC)

And of course immediately relavant to this topic is myiasis, I thought someone would have mentioned it already. Vespine (talk) 23:46, 31 January 2010 (UTC)

The tsetse fly's bite causes African trypanosomiasis, where the infection spreads to the brain. Naegleria fowleri is a form of "brain-eating amoeba". Also, under certain circumstances microorgaisms and species in smaller niches can evolve rather quickly, and the effects of global warming on most of those species are currently not known. ~AH1^(TCU) 00:53, 1 February 2010 (UTC)

Earwig. 124.157.247.221 (talk) 01:35, 1 February 2010 (UTC)

This has been recorded, although through the nose, not ear, and I'm not certain we'd regard it as a scientifically rigorous report, as the objectivity of the source is somewhat in doubt. --Dweller (talk) 12:06, 1 February 2010 (UTC)

Depth and temperature

Why is it very cold six miles underwater, but very hot six miles underground? 213.122.14.252 (talk) 18:38, 31 January 2010 (UTC)

Water is a liquid. Hot water tends to be less dense than cold so will float on top if it. Hence water will colder as you go deeper. Rock OTOH is a solid plus the source of heat is radioactivity in the rock itself plus primordial heat. The earth is slowly cooling down, but is doing it from the outside in, so the surface is cooler than the core. Theresa Knott | token threats 18:55, 31 January 2010 (UTC)

Why then does ice form at the top of lakes? 213.122.14.252 (talk) 19:16, 31 January 2010 (UTC)

Because it's lighter than the water, see water: The maximum density of water occurs at 3.98 °C (39.16 °F).[13] Water becomes even less dense upon freezing, expanding 9%. This results in an unusual phenomenon: water's solid form, ice, floats upon water... --Ayacop (talk) 19:23, 31 January 2010 (UTC)

OK. Why isn't the deep ocean heated up by pressure? 213.122.14.252 (talk) 19:26, 31 January 2010 (UTC)

It probably is, but again, hotter water is less dense, so any water heated by pressurization will tend to rise. --Ludwigs2 20:04, 31 January 2010 (UTC)

1. Is it naive of me to think of thermal energy as molecules jiggling around?
2. When a fluid expands, do the molecules jiggle around less, and if so, why?
3. Alternatively, does the fluid get colder simply because the molecules are further apart, meaning less jiggling per unit of volume, in which case how is the fluid any more able to absorb heat from its surroundings than it was before? 213.122.14.252 (talk) 20:28, 31 January 2010 (UTC)

1) No, that's precisely what thermal energy is (well, molecules and atoms jiggling around). I'll let somebody else tackle 2 and 3. --Tango (talk) 20:41, 31 January 2010 (UTC)

For 2, the answer is yes, if the expansion does work. When you let compressed air out of a bottle, the air does work against the atmosphere, and the nozzle gets cold. Similarily, water expanding against the weight of the ocean would also do work (of course, the expansion would come from an input of thermal energy, so the actual temperature of the water would rise. But the rise in temp would be less than expected from the amount of thermal energy put in). If, on the other hand, you let a gas expand into a vaccuum (some 17th or 18th century science guy did this, but I'm not sure who or why. Perhaps it was to test the phlogiston theory?), the temperature doesn't change. For point 3, the temperature article has some good stuff, though it's quite dense. Short answer is: temperature is not equal to thermal energy. Additionally, heat capacity (how much the temperature changes when thermal energy is added) is measured on a per mass or per mole basis, not a per volume basis. Buddy431 (talk) 21:26, 31 January 2010 (UTC)

Have I got this right? I have some gas in an expandable container, like bellows (yes, with the nozzle sealed). I forcibly expand the container: the gas stays the same temperature, because I did the work. If I instead I was forcibly holding the container compressed, and let go, letting it work to expand against atmospheric pressure, the gas cools down. If I let go of it in a vacuum, and we imagine the container expands until it stops expanding without offering any resistance along the way, the gas doesn't cool down. 213.122.14.252 (talk) 21:57, 31 January 2010 (UTC)

When you pull open the bellows, you're only doing some of the work; the air inside's doing some of the work, and the temperature will decrease. If you don't believe that the air is doing some work, try to immagine pulling apart a bellows with nothing in it (that is, a vaccuum) verses one that has some air in it. Buddy431 (talk) 22:55, 31 January 2010 (UTC)

OK, that works. :) Bit surprising. 213.122.48.165 (talk) 23:03, 31 January 2010 (UTC)

Having some trouble visualizing this. So far I'm at: water on the bottom of the ocean is heated by the pressure. It expands from the heat. It does work against the pressure as a result of expanding, so it doesn't heat up all that much. So water on the bottom of the ocean basically expands and rises. That doesn't sound right... is it constantly convecting, or does it just find its level, which I suppose would be the at bottom despite the heating? What if it's a system with a really compressible fluid and a lot of pressure, like the atmosphere of Jupiter - would the gas at the bottom of the atmosphere be heated up massively and become, er, much less dense, and rush to the top? Is there a bit of a delay between heating and expanding, which would cause constant frantic convection just because of pressure, or am I making up a lot of nonsense? 213.122.14.252 (talk) 22:09, 31 January 2010 (UTC)

Trouble is, pressure doesn't heat up the water. Pressure plus a decrease in volume heats up the water. Water at the bottom of the ocean is already compressed (what little amount it does), so the pressure doesn't affect its temperature. If water was heated up by a different means (like a hydrothermal vent) then convection currents would be set up, though probably not all the way up to the surface. Buddy431 (talk) 22:50, 31 January 2010 (UTC)

What happens to some ice-cold (OK, nearly ice-cold) water added at the surface? Does it sink to the bottom? Does it then compress and heat up and rise again? 213.122.48.165 (talk) 23:11, 31 January 2010 (UTC)

It will sink, and as it does, the increasing pressure will compress it a tiny amount, heating it up a tiny amount. So it's not like the liquid sinks to the bottom, then compresses and heats up; it's doing that all the way down, until it reaches a layer of water that's the same density (and same temperature), where it will stay (barring currents, etc.). Buddy431 (talk) 00:05, 1 February 2010 (UTC)

It is compressed as it sinks, which makes it heat up, which makes it expand again, canceling out the compression, canceling out the heating, leaving it no denser than it was at the surface. It can only reach the level where the water is the same density as very cold water at the surface. It won't end up any denser (or hotter, or colder). Is that right? 213.122.48.165 (talk) 00:59, 1 February 2010 (UTC)

No, both your scenarios are essentially the same thing. In the 1st scenario you decrease the pressure and the temperature will drop. In the second scenario you first inscrease the pressure which will raise the temperature, but then presumably you wait for the increased temperature to dissipate which means when you release it again the temperature will drop. What you have described of course is the simplest kind of heat pump. Water is NOT being heated by the pressure, you have to be careful: pressure is NOT Work (physics), it's an easy mistake to make, for the same reason you can't just get energy out of a magnet, a magnet can make pressure. Vespine (talk) 22:18, 31 January 2010 (UTC)

Excuse me but what is this first scenario where I decrease the pressure? Can't relate this to what I wrote, sorry. 213.122.14.252 (talk) 22:27, 31 January 2010 (UTC)

I was referring to your previous comment, when you forcibly expand the bellows (I presume with the nozzle sealed) you decrease the pressure and the temperature will decrease. Vespine (talk) 22:36, 31 January 2010 (UTC)

Oh, OK. I was confused by your answering down here with random indentation and by the word "both" when there are three scenarios. In the third one, the gas is essentially expanding in a vacuum so I take it you agree with Buddy431 that it doesn't heat up. Why is the first one different - my muscles do the work of decreasing the pressure in the gas, the gas doesn't do the work, so why should the gas lose energy? (Am I right in thinking that Buddy431's stipulation about doing work is because the work provides somewhere for the heat energy to go? It's a little confusing since many things, such as muscles, heat up when they do work.) 213.122.48.165 (talk) 22:55, 31 January 2010 (UTC)

Read the comment I made under your scenerios. When you pull open the bellows, the air does do some work; it's not all you. When you let it expand in a vacuum, with no resistance, it does no work. Buddy431 (talk) 22:59, 31 January 2010 (UTC)

Sorry it starts getting confusing when you are talking about so many related topics, by the time I replied there were already 2 other posts in between. Work is energy transferred by a force through a distance, your muscles provide the force, the gas provides the distance. Does that clear it up a bit? Part of the confusion might be that you think heating something up takes "work" so the opposite: cooling something down takes the opposite of work: (lack of work?) but what you are actually doing is not heating something up or cooling something down, it's heat transfer, all that is changing is the direction of that transfer, either case takes work. Vespine (talk) 23:18, 31 January 2010 (UTC)

Er, I thought the gas provides some of the force, by resisting less than a vacuum would. I get the heat transfer bit alright (the heat is transferred to the atmosphere, which you wouldn't notice since the atmosphere is very large). 213.122.48.165 (talk) 23:32, 31 January 2010 (UTC)

You're right 213. Vespine doesn't know what he's talking about. (Although "resisting less than a vacuum would" probably isn't the best way to put it. Better would be: "helping out more than a vacuum would"). Buddy431 (talk) 23:53, 31 January 2010 (UTC)

And just for the record, when I said the gas provides the "distance" I did actually mean "and the associated resistance across that distance." I was just simplifying. Of course opening bellows with the end closed takes more work then flapping your arms. Vespine (talk) 00:36, 1 February 2010 (UTC)

And importantly, the gas does NOT lose energy when you expand it, it loses temperature but increases volume, the energy remains the same!Vespine (talk) 23:20, 31 January 2010 (UTC)

NO. Gas can lose energy in expansion, and usually does. For an ideal gas, the volume has no effect at all on the internal energy. I think you mean that the total energy doesn't change (energy of gas + energy of everything else, including what the gas transferred energy to when it did work), which is just the First law of thermodynamics. And No to the post above your last one too. When pulling open the bellows with air in them, your muscles apply a force, and the gas does too. If you pulled apart a bellows with a vaccuum inside, the same amount of work would be done (same total force, same distance), but you would do all of the work. Buddy431 (talk) 23:50, 31 January 2010 (UTC)

So am I alright with "the work provides somewhere for the heat energy to go"? 213.122.48.165 (talk) 23:56, 31 January 2010 (UTC)

Well come on Buddy, that's not playing nice. I don't think you are correct either, where is the expanded gas losing energy to? Won't it GAIN energy? Such that if you release the force you used to expand the bellows the gas will be warmer than when it started? Also, if you really had a vacuum in the bellows, you wouldn't be able to expand it no matter how great a force you apply! That's how those glass holding suction cups work that can lift tons of weight. Unless you are also in a vacuum of course, which is a bit of a big detail to leave out. ;) Vespine (talk) 00:11, 1 February 2010 (UTC)

The gas is losing energy to whatever it's doing work on. For the case of a gas expanding against the atmosphere, it's transferring energy to the atmosphere (which will just heat up the atmosphere a tiny bit). And you certainly can pull against a vacuum, it's just hard when you're pulling against atmosphere. Atmospheric pressure is 14 lb/sq inch, so a suction cup even 7 inches square (a 3 inch diameter) could lift 100 lb. But in a barometer, just 30 inches of mercury can pull against a vacuum. Buddy431 (talk) 01:35, 1 February 2010 (UTC)

The Thermohaline circulation shows how complex the convection and advection currents in the ocean are. ~AH1^(TCU) 00:25, 1 February 2010 (UTC)

In reply to 165's last comment, the work doesn't really PROVIDE the place for the heat to go, the place was there all along, I would instead say the work provides a temperature gradient for the heat transfer to occur across. Vespine (talk) 01:08, 1 February 2010 (UTC)

I was thinking about a fridge. The refrigerant is compressed at the back of the fridge, it goes through a radiator, then it is squirted through a narrow gap into pipes inside the fridge. It expands a lot in these pipes. Presumably the particles in the refrigerant are jiggling less at this point than before it was squirted in. Why is that? I was thinking along the lines of "the particles are jiggling less because they've done some work", though it doesn't seem like they've done very much work. (I'm leaving out the phase change, I hope I can get away with that.) 213.122.48.165 (talk) 01:25, 1 February 2010 (UTC)

I think I've worked out where my confusion stems from, I was taking atmospheric equilibrium as the reference point, where as you guys are all talking about vacuum being the reference point which I admit is more correct, however in thought experiments I think it is easier to sometimes use the atmosphere as the reference point. Case in point the fridge example above: The refrigerant is compressed, as the volume decreases the temperature and pressure increases but the ENERGY effectively remains the same. What changes the energy is that the radiator takes the heat away and the energy of the refrigerant decreases at that point. Now you have compressed refrigerant at the same temp as the ambient atmosphere. Then when the refrigerant is squirted back into the pipes inside the fridge and expands the volume increases and the temperature decreases but the energy is STILL the same. At this point the "heat" in the fridge can transfer into the refrigerant until both are equal. Then the refrigenrant with more energy is taken out of the fridge and the cycle is repeated. The real work that is done here is done by the compressor, all the other work by the gas expanding and all that only confuses the issue IMHO. Vespine (talk) 01:47, 1 February 2010 (UTC)

(ec)It is mostly the phase change of the refrigerent that's pulling heat out of the frige, so you can't ignore it. See vapor-compression refrigeration for how the whole process works. Vespine's right, in that it's the compressor doing work, and when it does, the vapor comes out at a higher temperature, and higher internal energy, than when it came in. It then loses that energy from the compressor, plus the energy from cooling the frige, in the condenser. It's squirted into the coils in the frige, where it evaporates, which requires energy, which comes from the air inside the fridge (which is why it cools down inside). Buddy431 (talk) 02:03, 1 February 2010 (UTC)

Yep, I read that article a while back. I'm trying to comprehend how the energy in the fridge can transfer into the refrigerant. I find it necessary to go into detail, because I figure the heating of the refrigerant by the air inside the fridge consists of the evening-out of the jiggling of particles. Therefore I want to know what it was about expansion of the refrigerant that caused the particles in it to jiggle less. I could just say "the same energy occupies more volume, and therefore it can now accept some energy from inside the fridge," but if I imagine the individual particles, this explanation doesn't work, because the spreading out of the particles doesn't explain why each particle has less energy. 213.122.48.165 (talk) 02:13, 1 February 2010 (UTC)

Each particle doesn't have less energy. Pressure and temperature are two different things but are correlated, you can't change one without changing the other. The temp is like the "jiggling" and the pressure is more like "jostling against each other". When you decrease the pressure, the particles spread out and jostle against each other less but they still jiggle with the same energy they had before, it is the decrease of "jostling against each other" that accounts for the drop in temperature, not the individual particles losing any energy. Now that the particles aren't "jostling against each other" so much, they need more jiggle to bring them up to the same temperature they were before the pressure was decreased. Vespine (talk) 03:28, 1 February 2010 (UTC)

Yes you can reduce pressure without affecting temperature: release a gas into a vacuum (like I said, there was some guy who did just that to prove something or other). And in a gas anyway, temperature is related to the kinetic energy of the particles (the "jiggling", I think), NOT to how often they collide (the "jostling"). A gas with particles moving at the same average speed is a given temperature, regardless of what the pressure is. When a gas cools down while expanding, it is because the particles have lost energy in doing work, and they are moving at slower speeds. See the Kinetic theory article, especially the pressure and temperature sections. Buddy431 (talk) 04:18, 1 February 2010 (UTC)

Would the fridge not work without the phase change? (Something like a backwards stirling engine?) Would evaporation in a vacuum cause cooling? 81.131.48.166 (talk) 05:17, 1 February 2010 (UTC)

For your second question, yes, evaporating in a vacuum would cause cooling. A phase change from liquid to gas absorbs energy: see enthalpy of vaporization. I'm not sure about a compression fridge without a phase change, but I think it certainly wouldn't be as effective at cooling as the ones typically used. Buddy431 (talk) 17:01, 1 February 2010 (UTC)

What gas is green?

What gas is green in nature, without electrical charges or other tricks to make it glow? I remember in science class in high school talking about one specific gas that naturally occurs green. Maybe there's more than one.

People might not know the answer offhand, so can you recommend a good way to search? Or an article topic or category or something I could use? Thanks 24.20.200.67 (talk) 19:52, 31 January 2010 (UTC)

Chlorine gas is said to be green, looks more greeny/olive/brown to me. Nanonic (talk) 19:56, 31 January 2010 (UTC)

Fluorine too. But neither of these gases occur in nature. Buddy431 (talk) 20:20, 31 January 2010 (UTC)

I think its Fluorine I was thinking of. Thanks wikipedia!! 24.20.200.67 (talk) 21:31, 31 January 2010 (UTC)

Order of reaction Mg + HCl

How does the rate of the reaction Mg(s)+HCl(aq) depend on the concentration of HCl? Is it first order or second order? My class did an experiment in which both my group's data, and the averaged data of the entire class, clearly show that it is first order. However, the teacher claims this was wrong and gave us "real" data which showed the reaction to be second-order. I searched on the Internet and found some sources claiming it's first-order and some claiming it's second-order.

Which one is right? --99.237.234.104 (talk) 19:58, 31 January 2010 (UTC)

What is the balanced chemical equation for this reaction? What is the coefficient of the HCl (or the ionic part of it that is really reacting)? Often the coefficients are Order of reaction of each reactant. DMacks (talk) 21:18, 31 January 2010 (UTC)

This and this suggest that the mechanisms not really known, and that different concentrations and different types of acid can give different rate dependences, and that different people have gotten results that can't be reproduced. That sure inspires confidence. They cite an article claiming that it's second order though. You can download the article, and it becomes clear that even real scientists with lots of experience are getting different results based on how exactly the experiment is set up. I think the conclusion is that this probably isn't the best experiment to be teaching high school chemistry students about rate laws. Buddy431 (talk) 04:04, 1 February 2010 (UTC)

One thing this does illustrate is the importance of careful experimental procedures (and documentation of them) to make sure all variables are controlled. The results don't sound random/non-reproducible, but rather are just highly affected by experimental details. DMacks (talk) 06:51, 1 February 2010 (UTC)

Chemical formula of cellulose

Should the chemical formula of cellulose be (C
₆H
₁₀O
₅)
_n·H
₂O? --84.61.165.65 (talk) 20:44, 31 January 2010 (UTC)

No, the use of a dot in the formula suggests it is specifically a monohydrate (contains a single actual molecule of water bound in the structure). Are you perhaps thinking about the ends of the polymer chain, one of which has an H and one an OH? Those are a total of H
₂O but they are not "together as a water molecule". This is a general concern for the chemical formula of any polymer. WP:Chem would be the place to see if there is a need to adjust the infoboxes...I spot-checked a few polymer articles and none of them include end-groups in their chemical formula. DMacks (talk) 21:13, 31 January 2010 (UTC)

Energy from reversing desalination

The desalination article says that desalination requires large amounts of energy. Why then, if I pour some salt into a glass of fresh water, do I not get any energy back? 92.24.73.102 (talk) 21:40, 31 January 2010 (UTC)

Actually, dissolving table-salt in water absorbs energy (it has a positive Heat of solution). The desalination process does not result in overall addition of energy into the water (i.e., the products having more energy, which could be recovered by remixing). For example, distillation consumes lots of energy to boil the salt-water, but then that energy is released when the water-vapor condenses and the salt and water cool back to room temperature--the cooling water winds up containing the energy that was transiently in the pure water vapor, and is then discarded into the environment. Problem is that it's difficult to recover that energy efficiently--the products do not have a higher energy content, just a lot of energy was wasted (in a net sense) to get them separated. Is reverse osmosis energy-efficient (other than perhaps having to pump the water)? DMacks (talk) 21:53, 31 January 2010 (UTC)

The large amounts of energy required are either to evaporate the water (in distillation, including multi-stage flash distillation) or to force it through a semipermeable membrane (in reverse osmosis). In the first instance, energy is released when the steam condenses, but as DMacks pointed out, it's hard to recover this. In the second instance, you (in theory) could get back some of this energy by allowing normal osmosis to occur and capturing energy from the water movement created across the membrane. Needless to say, it's not worth wasting using fresh water like this to generate electricity. Buddy431 (talk) 22:06, 31 January 2010 (UTC)

There have actually been suggestions on capturing the energy of freshwater/saltwater mixing. See, for example "Energy Recovery from Controlled Mixing Salt and Fresh Water with a Reverse Electrodialysis System" Environ. Sci. Technol., 2008, 42 (15), pp 5785–5790, or "Extracting Renewable Energy from a Salinity Difference Using a Capacitor" Physical Review Letters 103, 058501 (2009). or any number of the news articles from last year, e.g [16] [17] [18] [19]. The thought is that the generation plants would be located at the mouth of rivers, where there already is substantial mixing of salt and fresh water. -- 174.21.224.109 (talk) 22:45, 31 January 2010 (UTC)

The first "salination" power plant in the world (or so the owners argue) opened last year~in Norway, see this page Jørgen (talk) 13:40, 1 February 2010 (UTC)

Perpetrual-reality

understanding the theroy of perpetual reality and its consept in to continues energy? —Preceding unsigned comment added by Angeldell (talk • contribs) 23:13, 31 January 2010 (UTC)

Sorry, I don't understand. Could you define "perpetual reality"? Are you perhaps referring to perpetual motion machines? Comet Tuttle (talk) 23:22, 31 January 2010 (UTC)

I refer to if reality as we know it! is continues and by understanding the way it works can we creat a machine based on it's machnics? —Preceding unsigned comment added by Angeldell (talk • contribs) 23:30, 31 January 2010 (UTC)

I think you're asking whether a machine might be made that does some useful work based on the simple fact that time advances. I'd suggest that this is unlikely, because entropy always increases (see Second law of thermodynamics). Comet Tuttle (talk) 23:48, 31 January 2010 (UTC)

If you are correct, then it sounds like, yes. You might look at the mathematical links under mobius for a model of something which could be considered continuous. I'm not sure Science has anything beyond possible speculation in the area of reality, and creating such a machine could prove the existence of reality having a continuous shape, which would be an interesting discovery for science. --Neptunerover (talk) 23:54, 31 January 2010 (UTC)

This response from NeptuneRover is a clear breach of the WP:NOR rule. It is not true - I advise our OP to ignore it. SteveBaker (talk) 02:42, 1 February 2010 (UTC)

I have this idea in mind for years that an active formal that is not yet seen that might prove that such a machine might be created. --Angeldell (talk) 00:00, 1 February 2010 (UTC)

Sorry, the phrase "active formal" doesn't mean anything in English — could you try a rephrasing? Comet Tuttle (talk) 00:08, 1 February 2010 (UTC)

(edit conflict x2)Are quantum mechanics, chaos theory and illusion partially relavent? ~AH1^(TCU) 00:06, 1 February 2010 (UTC)

Maybe he's wondering if it's possible to create a machine to simulate the entire universe. It's very hard to understand the question.

Angeldell: try posting the question in your native language. There are many editors here, maybe someone will know your language. Ariel. (talk) 01:00, 1 February 2010 (UTC)

possibly he's wondering if he can keep us guessing what he's after for the rest of eternity... --Ludwigs2 02:01, 1 February 2010 (UTC)

More suggestions: end of the Universe, vacuum energy, expansion of the universe, supercomputer, reality, perception of time, spacetime, Special Relativity, out of body experience, Eschatology, Large Hadron Collider, The Quantum Prophecy, Kali Yuga, Infinity, hypercube, information, self-reference. ~AH1^(TCU) 02:23, 1 February 2010 (UTC)

We need a clearer statement of this question before we can attempt to answer it. It is pointless to guess at what our original poster is asking and the answers presented so far are as likely to mislead as they are to inform. We should cease to comment until/unless the questioner can expand a little on what we're being asked. SteveBaker (talk) 02:44, 1 February 2010 (UTC)

If you don't even know what the question is, Steve, how can you decide which answer might be wrong? --Neptunerover (talk) 03:12, 1 February 2010 (UTC)

Steve's ". . . as likely to mislead as . . . to inform" is not equal to "wrong" in my understanding of English. The very point is that we can't decide right or wrong based on what is here. Bielle (talk) 03:24, 1 February 2010 (UTC)

I understood what the question was though. Steve doesn't. I gave the guy an answer fitting his question. --Neptunerover (talk) 04:58, 1 February 2010 (UTC)

If Steve doesn't understand the question, then he cannot judge how my answer relates to it. --Neptunerover (talk) 05:03, 1 February 2010 (UTC)

"I'm not sure Science has anything beyond possible speculation in the area of reality, and creating such a machine could prove the existence of reality having a continuous shape"? This is nonsense from beginning to end. Comet Tuttle (talk) 05:37, 1 February 2010 (UTC)

I see what you misunderstand, but you are misunderstanding what that statement says. Did you read the OP's question? It was a question mentioning perpetual reality as if it were a fact. I pointed out that science is not aware of such being a fact. As the OP mentioned a machine based on perpetual reality, I informed him that if there were to be such a machine, that would be quite a discovery for science. I didn't tell him to run build a machine! I didn't even tell him any such thing was possible. All I said was yes, if the OP was correct in all the statements he said about reality being perpetual and continuous, then yes, a perpetual reality-based machine would be a yes, or at least it sounds like it, for how would I know? --Neptunerover (talk) 06:06, 1 February 2010 (UTC)

Guys, let it go. the question was confused, and there's no need to go over whether the answers are confused as well. I think what we all need to do is go home, take some heavy-duty mind expanding drugs, and reconsider the issue from an altered state of perception. sound like a plan? --Ludwigs2 06:14, 1 February 2010 (UTC)

February 1

Earth gear

When I was younger I said to my mom that we could create a good energy source using the earth's rotation. All I need was a gear which the earth could spin using its rotation much like the gears in clock work. This spinning gear would then be used to generate electricity. My mom said it was impossible. Why?--121.54.2.188 (talk) 02:09, 1 February 2010 (UTC)

The difficulty of finding something to mount this gear to, such that the earth will spin it. --Tagishsimon (talk) 02:11, 1 February 2010 (UTC)

You could probably find a way to extract energy from a foucault pendulum. It's unlikely that you'd be able to extract much. Essentially, you'd be tapping off the reservoir of angular momentum (or rather, rotational kinetic energy, and slowing the earth's rotation. Nimur (talk) 02:36, 1 February 2010 (UTC)

You can only do that once. After that the pendulum is spinning at the same rate as the earth, and you can no longer extract any energy. It would be a violation of conservation of angular momentum if you could constantly extract energy from the rotation of the earth by slowing it down. Ariel. (talk) 08:31, 1 February 2010 (UTC)

I guess tidal energy is sort of that. 213.122.48.165 (talk) 02:39, 1 February 2010 (UTC)

Perhaps a gyroscope in a vacuum cylinder spinning on frictionless magnetic bearings at one of the earth poles would stay still as the Earth turned, allowing the difference in rotation to turn gears to speed up the rotation and turn a dynamo?Trevor Loughlin (talk) 03:33, 1 February 2010 (UTC)

See what I wrote above. You can only do that once, because you need to conserve angular momentum. Ariel. (talk) 08:31, 1 February 2010 (UTC)

If I understand you correctly, the maximum energy you'd get out of that would be somewhat less than you had to put in to it to get the gyroscope spinning in the first place. --Tagishsimon (talk) 03:40, 1 February 2010 (UTC)

Well, I'm not quite clear on Trevor Loughlin's idea. But, it's possible to harness energy that's stored in the form of Earth's rotation - actually netting more energy than you expend to collect it. You aren't creating any energy - you're just harnessing kinetic energy of Earth's rotation. Presumably, that energy is left over from the formation of the solar system (and by extension, from the Big Bang and cosmogenesis... whether the energy was created or has always been there is irrelevant for this discussion). Presently, that energy takes the form of rotational kinetic energy in the planetary rotation of the Earth. If you could actually build a device that could be spun by the Earth, you would be ever-so-slightly slowing down the enormous planetary-sized flywheel; and you could extract energy from it. It's not perpetual motion - there's a finite (but really, really huge) amount of energy to extract. However, the impracticality of building such a device makes it less attractive than harnessing other natural energy reservoirs (tidal motions have already been brought up). Nimur (talk) 03:58, 1 February 2010 (UTC)

No, i's not impractical. It's impossible unless you can transfer the momentum somewhere. With tides the momentum goes to the moon. Ariel. (talk) 08:31, 1 February 2010 (UTC)

The gyro would not be spinning horizontally like a top, it would be at right angles to the Earth-dynamo axis. Would this make a difference?Trevor Loughlin (talk) 03:58, 1 February 2010 (UTC)

No. How does this differ from spinning a bike wheel then putting the bike down? --Tagishsimon (talk) 03:59, 1 February 2010 (UTC)

Oh come on! It's easy! Buy a simple electrical generator with a large wheel welded to it's input shaft. Take it to the South Pole and bolt it firmly though the ice and into the bedrock beneath with the input shaft pointing straight up and the wheel laying horizontally. Tie a long rope to one side of the wheel. Tie the other end of the rope to a nice strong nail hammered into the south pole of the moon. As the earth spins, so the generator turns at roughly one revolution per day (actually, not quite that because the moon orbits the earth once a month). You'll keep generating power until the earth eventually stops spinning - an event that would be very slightly hastened by doing this. (Actually, since the moon does set below the horizon even at the south pole, you might need to erect a very tall tower and mount your generator on top of that to ensure you have a continual path for the rope.) There are of course some trivial engineering issues to deal with! SteveBaker (talk) 08:09, 1 February 2010 (UTC)

Now this could work. It would do rather interesting things to the orbit of the moon. Especially if you don't lengthen the rope. (But you could never actually make the earth stop spinning, the best you could do would be to have it spin at the same rate as the orbit of the moon. But I think you could get that to any desired slowness you want (very far away moon), just not zero.) Ariel. (talk) 08:31, 1 February 2010 (UTC)

I think it would be hard to get the rope really tight enough that the elliptical orbit of the moon would be a problem, and the rope doesn't need to be tight for this to work. But to assuage your concerns, I'd be prepared to spend the extra to buy bungee cord. (In truth - if you could do this at all, you might be better off to forget the generator and use a conductive wire instead of rope - generating electricity directly from the motion of the wire through the magnetic field. You'd need two wires - one from the north pole and one from the south with a wire running across the lunar surface to complete the circuit.) SteveBaker (talk) 19:19, 1 February 2010 (UTC)

SteveBaker, you've solved the energy problems of the earth. Except that people who like eclipses and use a lunar calendar would object since as you transfer momentum to the moon it will get farther and farther away. (You are lucky the moon and earth rotate in the same direction, otherwise you might just bring the moon crashing down on us.) Ariel. (talk) 19:28, 1 February 2010 (UTC)

That won't be a problem because, sadly, eclipse-lovers and anyone who even knows where to find a lunar calendar will have died during the three centuries of enforced labor required to hand-make half a million kilometers of bungee cord and an antarctic generator tower several hundred miles tall. The lunar antipodeal nail could be purchased at Home Depot for approximately 50 cents and I was planning to repurpose the spare generator out of my 1963 Mini Cooper - so relatively little loss of life would be entailed in those phases of the construction project. Rewiring the major world-wide power grids to run off 12 volts with a positive ground will have to be someone else's problem because I have to talk NASA into lending me one of those million dollar space-hammers. :-)

A vaguely related topic is the use of Gravity assist to "steal" energy from other planets orbital momentum, rather than their rotational energy. The energy is not free - it causes the planet's orbit to slow. Mitch Ames (talk) 12:13, 1 February 2010 (UTC)

The Foucault pendulum suggestion was correct, the objection to it was wrong. The only problem is that to get a significant amount of energy the pendulum would have to be miles high. The winds in winter storms, it might be worth noting, are powered by the same mechanism -- that is, they draw their energy mainly from the Earth's rotation. Looie496 (talk) 17:11, 1 February 2010 (UTC)

You object to conservation of angular momentum? The winds are not powered by the rotation of the earth, they are powered by the sun. The rotation just effects what direction they will go in. Ariel. (talk) 19:24, 1 February 2010 (UTC)

Hmmm - so we could build a vast, elliptical train track - with the major axis of the ellipse running north-south. The train would be loaded with bowling balls which we'd release from the side of the train on the southern leg of the journey - picking them up again on the northern leg after the coriolis effect had moved them across the width of the track. Recovering the kinetic energy from the bowling balls and using this to power the train itself is a mere engineering detail that will be left as an exercise for the reader. SteveBaker (talk) 19:19, 1 February 2010 (UTC)

I assume this is a joke in reply to Looie496 :) (Since this will not work.) Ariel. (talk) 19:24, 1 February 2010 (UTC)

Why not? SteveBaker (talk) 19:46, 1 February 2010 (UTC)

Because to move the balls north on the return trip you would have to spend energy in the train to speed them up against the (reverse) coriolis effect. And conservation of angular momentum also says no, since you have nowhere to transfer the momentum of the rotating earth. Ariel. (talk) 20:06, 1 February 2010 (UTC)

Oh, yeah - conservation of angular momentum...duh. SteveBaker (talk) 20:21, 1 February 2010 (UTC)

All joking aside, I don't see any reason a gyroscope running perpendicular to the earth's axis wouldn't feel some force from the earth's turn. The force would be incredibly weak, so actually constructing a device so frictionless that it would turn is probably impossible, but I don't think there are any theoretical problems with the idea. APL (talk) 19:41, 1 February 2010 (UTC)

It would feel a force. But you can only collect the energy once, after that the force would move (accelerate) the gyroscope, and there would no longer be a force. The only reason a foucault pendulum turns is that they work really hard to make sure there is no force at the joint (frictionless). Ariel. (talk) 20:06, 1 February 2010 (UTC)

linear permanent magnet bearing?

I have heard about rotational magnetic bearings. But has anyone invented an (unpowered) linear magnetic bearing, which could do away with wheels without the costs of electromagnetic levitation? And don't cheat by using high temperature superconductors floating above liquid nitrogen-this has its costs-I'm talking about ordinary magnets. Is it theoretically possible? There is no violation of thermodynamics or conservation of energy laws to make it impossible(?)Trevor Loughlin (talk) 03:52, 1 February 2010 (UTC)

See Earnshaw's theorem. It's not possible. Rotational ones don't work either. Ariel. (talk) 06:55, 1 February 2010 (UTC)

See [20]. Wikipedia has a short article on the Barnett effect. Cuddlyable3 (talk) 11:45, 1 February 2010 (UTC)

Thermal Gravimetric Analysis

Is it possible to determine the composition of a mixture of CaC2O4 and CaCO3 using Thermal Gravimetric Analysis? If so, how? —Preceding unsigned comment added by 70.68.120.162 (talk) 04:04, 1 February 2010 (UTC)

Thermogravimetric analysis, for those interested. --Tagishsimon (talk) 04:07, 1 February 2010 (UTC)

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misevaluation, but it is our policy here to not do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn how to solve such problems. Please attempt to solve the problem yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. TenOfAllTrades(talk) 04:17, 1 February 2010 (UTC)

Contracting diseases via intercourse with cells?

If an individual has sexual intercourse with a cancerous cell (e.g. a mutated cell cluster or cancerous tissue as detected in a biopsy), will they contract cancer? Does it matter if the disease that the cell carries is a sexually transmitted disease (e.g. gonorrhea); that is, is it more viable or likely that the person will become infected as a result of intercourse? Further, why or why not would this happen? As much as this may seem like a facetious question, I am genuinely curious and would appreciate any insight that can be offered, whether it is theoretical or concrete. Thank you, Arcendet (talk) 06:00, 1 February 2010 (UTC)

You will not 'catch cancer' by having sex with someone who has cancer. If the cancer was generated by an underlying sexually transmitted disease (e.g. gonorrhea or HPV) you might catch that particular disease, and that disease might (eventually) induce cancer in you as well, but there is no necessary, direct, or causal relationship implied there. relax, you're relatively safe. next time use a condom. --Ludwigs2 06:18, 1 February 2010 (UTC)

Actually we don't know that. See Devil facial tumour disease which is a transmissible cancer (we actually have a page on that). There is no reason to assume it could not happen to humans too - and in fact the page lists one case where it happened. Especially if the lag/incubation period is very long it would be very hard to figure out the correlation. Ariel. (talk) 07:01, 1 February 2010 (UTC)

Uh... those refer to dogs and tasmanian devils... and (excuse me) apparently to Syrian hamsters as well. There is no known pattern of a transmissible cancers in humans, or even in primates. assuming that the OP is not a tasmanian devil, canid, or Syrian hamster (and has not been using Syrian hamsters in some fairly perverted way) I see no reason to alarm him/her over the risk of transmissible cancers. --Ludwigs2 07:20, 1 February 2010 (UTC)

And a human too, did you miss that part? It's not just theoretically possible, it's actually happened. I never said it was common, I said we don't know. He did ask for even theoretical information. Ariel. (talk) 07:43, 1 February 2010 (UTC)

I missed any mention of Devil facial tumour disease being transmissible to humans and I would think the amount of research that has been done on it is a reason to assume that would have been noticed if it were possible. However research into dog to human STD's is as yet only in its infancy puppyhood. Cuddlyable3 (talk) 11:33, 1 February 2010 (UTC)

I don't think Ariel is referring to Devil facial tumour disease being transmissible to humans. Rather some surgeons have had tumours that have been transmitted via accidential implantation on an injury site with the article linking to this specific reference [21]. This clearly is very uncommon and requires a specific set of circumstances (i.e. isn't something that occurs in the 'wild' if that has any meaning for humans) and tumour types and isn't associated with sexual intercourse nor blood transmission but Ariel never said it was. Transplanted organs can of course also effectively transmit cancer although I don't know if you'd call that a transmittable cancer. Nil Einne (talk) 14:16, 1 February 2010 (UTC)

It would have to be a mighty big cell to have sexual intercourse with it! As for human transmissible cancers, see HPV which is responsible for transmitting cervical cancer. However, as I assume the questioner is a man, he won't actually catch cervical cancer (not having a cervix), but apparently can get cancer of the penis. You're at most risk of catching an STD if you don't use a condom. It's possible cervical cancer could be classified as an STD. --TammyMoet (talk) 09:09, 1 February 2010 (UTC)

As an aside, HPV infection is also associated with oropharyngeal cancers – cancers of the mouth and throat – which again are of concern to both women and men. TenOfAllTrades(talk) 14:28, 1 February 2010 (UTC)

File:Cases of HPV cancers graph.png is perhaps of interest here.

However as explained by Ludwings, this isn't really a transmittable cancer at least by the definition used in both of the earlier linked articles. Rather the virus is transmittable which when it infects a human can eventually (along with a whole host of other changes) lead to cancer in a small number of people. This compares to a transmittable cancer where the cancerous cells themselves infect the other host. A more complicated case which perhaps illustrates the complexity is HIV which usually compromises the immune system can also greatly increase the risk of cancers [22]. This includes for example Kaposi's sarcoma itself caused by Kaposi's sarcoma-associated herpesvirus [23]

Nil Einne (talk) 14:43, 1 February 2010 (UTC)

Scientific Film Association

The Scientific Film Association was constituted on 20 November 1943 to promote the use of the scientific film in order to achieve the widest possible understanding and appreciation of scientific method and outlook. Active members included eminent film makers such as Sir Arthur Elton and Edgar Anstey. Several standing committees were set up and the Medical Committee became a leading authority on medical films in the UK and published several catalogues of appraisals of films on specialist medical topics. The SFA, together with the French Institut de Cinematographie Scientifique, established the International Scientific Film Association in October 1947.

There is no mention of the SFA in Wikipedia but one note of an Italian who was an ISFA member. Do you think that I should prepare a possible entry? Michaelsthgate (talk) 10:35, 1 February 2010 (UTC)

First look at WP:N. Have you citations that verify the SFA is a leading authority? Cuddlyable3 (talk) 11:19, 1 February 2010 (UTC)

Leading or not, if it existed and produced lasting artefacts like catalogues, then I would go ahead and include it. But, as Cuddlyable said, you must provide citations for every claim. --Heron (talk) 12:43, 1 February 2010 (UTC)

Googling the name produces articles about the association in Nature and several other significant references. I don't think you'd have a hard time establishing notability. So yeah - I think Wikipedia needs an article about this. As others have pointed out - you need to be sure that there are a good number of references for the article in general - and in particular that all potentially controversial statements are individually tagged with a specific reference. I look forward to reading it! SteveBaker (talk) 18:59, 1 February 2010 (UTC)

ELECTRIC WIRE

IS THERE ANY INFORMATION ON ZERO HALOGEN FLAME RETARDANT CABLES? —Preceding unsigned comment added by 118.94.161.137 (talk) 13:15, 1 February 2010 (UTC)

You can find references to them in our articles on Trirated cables and Low smoke zero halogen. Does that help? Gonzonoir (talk) 14:21, 1 February 2010 (UTC)

Do wires carrying DC get corroded more or less easily than those carrying AC?

Do wires carrying DC get corroded more or less easily than those carrying AC, or are they the same? --173.49.13.59 (talk) 13:32, 1 February 2010 (UTC)

Yes where dissimilar metals are in contact e.g. aluminium cable to brass or copper connectors. This [24] reports "5% of total corrosion costs in USA, [mostly arise] from electrified DC transit system operations". Cuddlyable3 (talk) 14:40, 1 February 2010 (UTC)

Otherwise, there should be NO difference between AC and DC that I know of. See Electrolysis and Electrolytic cell for relevant info. See the related Sacrificial anode for corrosion prevention. Also Galvanic corrosion--220.101.28.25 (talk) 15:29, 1 February 2010 (UTC)

Wires get corroded by heating-up. They heat-up since they have a typical resistance per unit length (depending on the material), so when current flows through them, it disspates power in them given by P=I²•R (where I is the current). Note that AC current must have a larger amplitude than the DC current, to generate the same power. The result of integrating the square of the current over time, to find the mean of the power-contribution, is called [Root mean square] (or RMS). So an ac current of the same RMS as a dc current will dissipate the same amount of power along thw wire, and will generate the same amount of heating-up. The result of the RMS integral is dependant upon the waveform of the ac current. For sine (cosine) waves, the RMS value is sqrt(2)/2 (=~0.7071...) of the amplitude. For example, in incandescent light-bulbs, you need an ac amplitude of current, which is larger (times the inverse RMS amount) than a constant dc current, to produce the same amount of heat (and light). --Shimon Yanowitz (talk) 16:39, 1 February 2010 (UTC)

I would expect more electrolytic effects from wires carrying DC than AC, unless the insulation is perfect. With AC, the metal removed in one half cycle might be returned in the other half cycle, but with DC there should be a continuous deposition of metal, provided there is leakage current, as when wires are underground and there are small cracks in the insulation. There is also electrolytic action causing ferrous metal underground to lose metal when copper is nearby, but that should not depend on AC versus DC current in the copper, as long as the circuit has a return path and is not just unipolar. Edison (talk) 20:43, 1 February 2010 (UTC)

Advice on modelling a flood

For a creative project I'm imagining a scenario in which unprecedented rainfall causes disastrous flooding in (inter alia) Cambridge, UK. The premise is unrealistic, but I want what follows from it to be as plausible as possible. So I'm seeking tips on how I could model what flooding would look like in this town: I'd like to be able to produce a map showing which parts of the city are still above the flood level.

I guess I would need to find values for variables, including:

1. rate of precipitation (how much rainfall per time period)
2. topography of the area
3. effect of rainfall upstream
4. ?season (drains clogged with leaves in autumn? Water table higher at certain times of year?)

Can anyone give me pointers on how I could realistically model the flooding of the town, if I had set values for these variables? If I wanted to say "it has rained solidly for x days at a rate of y centimetres per day", how can I figure out what effect that would have on the ground? I'd be very grateful for tips on ways to get started, or on factors I'm missing from my list. Gonzonoir (talk) 13:44, 1 February 2010 (UTC)

You will want a relief map of the area such as the maps with contour lines published for the U.K. by the Ordnance Survey. Without effective measures of Flood control, floodwaters will settle within a given elevation contour line. Cuddlyable3 (talk) 14:27, 1 February 2010 (UTC)

Further, you'd need to estimate flood points and try to work out a flow pattern. rising water does not create floods; floods are created when water passes the lowest point on the river bank, and how it flows from there will determine damage patterns (damage will be more extensive, for instance, where water can pick up momentum or build up pressure). You'l also want to consider whether you're talking about natural flooding (where water passes a bank and more or less gradually fills the surrounding region) or catastrophic flooding (where the failure of a natural or man-made containment wall releases huge quantities of water rapidly). --Ludwigs2 15:46, 1 February 2010 (UTC)

Historical information about previous floods in the city may be helpful (perhaps to confirm whether your model has validity). A google search throws up links to photographs of previous floods. You may be able to estimate how high the water was at the stated locations but I didn't find an aerial photograph. Museums and pubs often seem to have photos of floods :-) --Frumpo (talk) 16:33, 1 February 2010 (UTC)

Another variable you need is the percolation/drainage capability of any area - and that's complex since drainage capabilities of any area will be affcted by the drainage capability of another area (e.g. if both discharge into a common and limited drainage channel). --Tagishsimon (talk) 17:37, 1 February 2010 (UTC)

Many thanks all - this is exactly the sort of thing I was after. Some follow-up questions:

1. The OS 1:25 000-scale map for the city has contour intervals of 5 metres. Cambridge is as rugged and mountainous as a pancake, so there ain't that many of them. Does anyone know of a resource showing contours at a finer level of detail?
2. The point about percolation is well taken. Can I make the blanket assumption that the broader the scale of the storm (i.e., the greater the size of the area that's getting rained on), the worse drainage at any one point will be?
3. Ludwigs2, just to clarify, by "flood point" you mean the spot(s) at which the river breaks its banks? That seems like an area where Frumpo's suggestion of gathering data on earlier floods would be helpful. Gonzonoir (talk) 20:15, 1 February 2010 (UTC)

Speed of heat transfer

Can we say that heat is transferred at the speed of electromagnetic waves throughout a medium? I understood it is transferred by conduction, for instance at the speed of sound, but isn't there a radiation contributing factor through this medium?--Email4mobile (talk) 16:53, 1 February 2010 (UTC)

There are three important ways heat is transferred: radiation, which goes at the speed of light; diffusion, which does not have a definite speed; and convection, which depends on bulk movements of the medium. In many situations radiation does not play a significant role and diffusion is the main factor. "Conduction" is the same thing as diffusion here, and it does not go at the speed of sound -- its speed drops off with distance. Looie496 (talk) 17:01, 1 February 2010 (UTC)

I'm afraid I couldn't get it. Let me rephrase the question: What is the time required to cause an infinitesimal or tiny change in temperature provided that a significant change has taken place at a given distance of known medium (with its characteristics involving heat transfer)?--Email4mobile (talk) 17:21, 1 February 2010 (UTC)

It depends on what your medium is. If it is transparent to infra-red radiation then a solid object immersed in the medium will be heated most rapidly by electromagnetic radiation (although the medium itself is not heated this way becqause it does not absorb the e.m. radiation). If the medium is opaque to infra-red radiation then a thin layer near its surface is heated rapidly by e.m. radiation but the bulk of the medium has to be heated more slowly by convection in a liquid or gas or by conduction in a solid. Gandalf61 (talk) 17:37, 1 February 2010 (UTC)

Then at what (slowly) speed will the heat transfer by conduction and convection occur? This question will help me save the time asking another question about a maximum theoretical possible speed for sound if it will be the same, thanks in advance.--Email4mobile (talk) 18:04, 1 February 2010 (UTC)

The question you phrased is probably not the question you want to be answered. As any (as far as I know) medium is transparent to some kind of electromagnetic radiation, and as any material will radiate on any frequency (albeit and notably not at the same intensity) any change in temperature will reach any other body at the speed of light. The energy exchanged in this way will in most cases be negligible compared to the energy flow by slower convection and conduction. 95.112.190.236 (talk) 18:28, 1 February 2010 (UTC)

Let's try to break this down a bit.

• Radiation: If you had a hot body and a thermometer separated by some distance in a hard vacuum - then such heat as would be transferred from one to the other would happen via infrared radiation (mostly) and that travels at the speed of light (because it is light).
• Conduction: If you had a steel bar and heated up one end with the same thermometer at the other end, then because steel is opaque to infrared light, the heat would have to travel from one end to the other by conduction...a much slower process in which the jiggling of a hot atom at one end knocks into another atom next door and sets that jiggling too - and atom-by-atom, the jiggling spreads from the heat source to the thermometer. The speed at which that happens varies dramatically from one material to another. At one extreme, metals like steel conduct heat fairly quickly (although nothing like as fast as the speed of light). At the other extreme, materials such as aerogel or the stuff they make space-shuttle heat tiles out of conduct heat incredibly slowly. Everything depends on the structure and constituents of the material. The speed of conduction is nothing like the speed of sound. Sound travels through steel bar at hundreds of miles per hour - but when you stick a metal teaspoon into a near-boiling cup of coffee - it might take several seconds for the heat from one end of a six foot chunk of steel to be noticable at the other end.
• Convection: If you put a hot body into a room that's full of air - and put one thermometer six feet to the left of it and a second thermometer six feet above it - then the first thermometer will take a lot longer to register the temperature rise than the second one. That's because as the air around your heat source warms up, it expands. It's density gets lower...the air becomes "lighter". This lighter, warmer air tries to float on top of the denser air - just like a piece of wood floats on water. As the air rises upwards, it reaches the thermometer above the heat source quite soon - but that warm air has to be replaced by cool air from around the sides - so the conduction of heat through the air is messed up by that air flow and the thermometer off to the side may never show a temperature increase at all! This convection effect relies on the materials being free to move around - so you don't see convection in a steel bar - but you do see it in water, mercury, air, etc. Even within liquids, the runnier the liquid, the faster the convection currents can move. The amount of convection in (say) treacle is far less than (say) in water. I suppose that the rate of convection might be limited by the speed of sound...but I don't think so. At any rate, it's not usually that fast.

So the answer to your question is fairly complex. In many situations, the transfer of heat from one place to another depends on all three of these mechanisms. If you light a fire in your fireplace, you are immediately warmed by the thermal radiation - but as the hot air produced by the fire goes up the chimney, you feel a cool draft from the colder air in the rest of the room. However, heat from the fire is also warming up the walls and floor of your house by conduction - and you get some warmth that way too. Figuring out the results of those three things complicates the answer to the point where we can't give you any kind of measure of speed without knowing precisely what materials and distances are involved. SteveBaker (talk) 18:44, 1 February 2010 (UTC)

Just to add to Steve's reply, in a thin column of air (or other fluids), the descending cool air can't move to the side of the ascending warm air, and thus inhibits free convection. This is one of the methods in double-glazing. CS Miller (talk) 20:26, 1 February 2010 (UTC)

Europa (moon)

When Europa warms up I thouhgt this is possible Europa can end up back to watery globe. The surface is made of white ice which is thick layers of oxygen. If scinetist think Europa is once cover with oceans when gravity is too low how can they keep a substantial atmosphere? Isn't Europa even smaller than Pluto so outgassing should be even likely--209.129.85.4 (talk) 17:29, 1 February 2010 (UTC)

I don't know about "when" Europa warms up - that seems unlikely to happen before the sun turns into a red giant...and even then, not for long. Anyway - what prevents all of the oceans from boiling off into space is precisely because there is all of that ice there. If the planet warmed up enough for the ice to melt, it would start to boil. On a larger body, the water vapor would form an atmosphere, the pressure of which would gradually increase until there was an equilibrium between liquid water and water vapor. But Europa has insufficient gravity to keep that water vapor as an atmosphere - so rather than the pressure building up to maintain that equilibrium, the oceans would keep on boiling until they were all gone. If there are liquid oceans there - they are locked below a thick layer of ice which (being a solid) is only sublimating away very slowly. Outgassing (of a sort) is one of two proposed mechanisms to explain the cracked appearance - yet super-smooth surface of the moon. It is thought that the surface ice may occasionally crack due to tidal forces from nearby Jupiter. The pressure in the oceans beneath the ice would force geyser's of water to be forced up through the crack - only to freeze as soon as it reached the surface. This mechanism would continually force water from the liquid oceans, up through cracks - across the surface. Because warm water from the ocean is likely to slowly melt the underside of the ice - undermining it and causing more cracks - there would be a slow recycling of water through the ice sheets. This seems to be the most likely explanation for the observations of Europa - but there is another plausible theory that there is no liquid water - but merely slowly flowing ice beneath a brittle surface layer. SteveBaker (talk) 18:28, 1 February 2010 (UTC)

is melvin manhoef okay?

? —Preceding unsigned comment added by 67.246.254.35 (talk) 17:53, 1 February 2010 (UTC)

Does this question has any scientific aspect? (Mind you, you're asking this on the Science Reference desk, not on a news desk.) 95.112.190.236 (talk) 18:08, 1 February 2010 (UTC)

Our Melvin Manhoef page doesn't list any current injuries, and I went to Google News and typed "Melvin Manhoef", and 25 stories were found about this weekend's fight. I only read one of them, which didn't mention any lasting injuries. For future reference, 95 is correct, this would probably belong better on the Entertainment desk; and also for future reference I do recommend a news site like Google News for "what happened yesterday" questions like this; it's faster than coming here to Wikipedia, asking, and then waiting several hours for someone like me to go Google it for you. Comet Tuttle (talk) 18:27, 1 February 2010 (UTC)

Ah, this is our world today and I don't have much capacity to complain about but, please all of you think twice, is the state of health or injury of any human being really a matter of entertainment? I think, yes, in the world as it is, it is, but it should not. 95.112.190.236 (talk) 18:39, 1 February 2010 (UTC) (And sorry if this violates Wikipedia:NPOV and current political correctness.)

Good one! I suggested the Entertainment desk not because injuries are hilarious, but because Melvin is the Light Heavyweight World Champion of Cage Rage, which is a form of entertainment. Questions about injured boxers or wrestlers belong there too, unless, I suppose the questioner is asking about the details of the fighter's subdural hematomas. Comet Tuttle (talk) 19:18, 1 February 2010 (UTC)

So isn't it illegal to inflict such injuries to anyone, or to promote or endorse such doings? Why aren't all those rubbernecks paying attention and money to see such incidents simply going to prison? 95.112.190.236 (talk) 19:55, 1 February 2010 (UTC)

Presumably these actions are between consenting adults? Googlemeister (talk) 21:03, 1 February 2010 (UTC)

If so, why then is there any fuss about any injuries consented? (And if in any countries with national health care, is there any compensation for the non-consent-forced-contributors?) 95.112.190.236 (talk) 21:53, 1 February 2010 (UTC)

I'm surprised that there is no boxing license article. 124.157.247.221 (talk) 21:40, 1 February 2010 (UTC)

Can I eat my father's popcorn?

For the longest time I didn't know it was there. It was in the back of a cabinet. I've never bought popcorn, so it must be his.

My father moved out 11 years ago.Vchimpanzee · talk · contributions · 18:48, 1 February 2010 (UTC)

Are you asking if it has gone bad? Popcorn will basically not go bad IF it has not been exposed to moisture or bugs. But you should be able to tell by looking at it if it has gone bad—with over a decade of time, it has either probably gone reeeeeaallly bad (it will be able to carry out a conversation with you), or it is just fine to eat. Note that this may vary depending on any flavoring or coating on the popcorn—if it has all sorts of synthetic butter stuff on it, I don't know whether that stuff goes bad, stale, whatever. I would be a bit wary of that stuff. --Mr.98 (talk) 18:58, 1 February 2010 (UTC)

I found a bunch of other stuff too. Sugar, cocoa, pancake syrup ...Vchimpanzee · talk · contributions · 19:07, 1 February 2010 (UTC)

Assuming this is a commercial product, it probably has a relatively long shelf life. at any rate, or popcorn to go bad it needs to absorb moisture, and if it absorbs any significant amount of moisture is won't pop.

That being said, popcorn costs a dollar or two (US currency) per pound. Unless you're talking about a huge quantity (e.g., your father stockpiled shelves of the stuff), it's probably wiser just to toss it and buy a new package. --Ludwigs2 19:08, 1 February 2010 (UTC)

It's a very small amount. That's why I never saw it. Vchimpanzee · talk · contributions · 19:11, 1 February 2010 (UTC)

(after ec) Answering quite formally, we are not to give legal (that stuff is owned by your father, ain't it?) nor medical advice (no one would like to be liable if you get stomach cramps or worse) I have to tell you that we cannot answer your question. But I can tell you what I did in a similar situation (which is not even original research, I did not research, I just did it). I used the sugar, threw away the cocoa (it tastes bitter when rotten, but it also tastes bitter when fresh), and I had a taste on the syrup before deciding it didn't taste of and was sticky enough that it would have not enough free water for any bacteria to live in it. If you are not in really dire need of food, throw away whatever you're in doubt of being harmful. 95.112.190.236 (talk) 19:23, 1 February 2010 (UTC)

This is why we have "use before..." dates - are there any of those on these products? I would be surprised if any of the things you mentioned would be a problem - providing no moisture got into them - and no rodent chewing/droppings are evident. SteveBaker (talk) 19:30, 1 February 2010 (UTC)

"Best before" dates are set very restrictive, to protect the selling company from lawsuit. It's not a Median lethal dose test. (Which is well, that is is not.) 95.112.190.236 (talk) 19:38, 1 February 2010 (UTC)

The popcorn is not in its original container. Neither is the sugar. I could check the cocoa.Vchimpanzee · talk · contributions · 20:24, 1 February 2010 (UTC)

Old popcorn loses the internal moisture needed to explode into steam and make it pop, so the size of the popped kernals should decrease and the number of unpopped kernals should increase in very old popcorn. We cannot predict other harmful effects such as fungus or insect infestation. Edison (talk) 20:36, 1 February 2010 (UTC)

I missed one the responses. As executor of my father's estate and the only one who inherited from him after his wife agreed to a certain amount, the food is mine.Vchimpanzee · talk · contributions · 20:39, 1 February 2010 (UTC)

So I assume it has some kind of personal, memorable value. I encountered this from personal experience, in a time when Germans socialists where on top and I didn't know if I'll ever get a job again, thus valuing any left food twice as high (not wanting to be in need to beg the apparatchniki for sustenance). My personal advice is: throw away what is clearly rotten, use what can safely be eaten, and await a time where the rest of it clears out to be on one or the other side. 95.112.190.236 (talk) 21:15, 1 February 2010 (UTC)

None of the things you mentioned will spoil, but you might have bugs in them, and the taste might be bad. But from a safety point of view, I would be comfortable eating them. The popcorn will almost certainly not pop, and the cocoa might taste bad. The sugar and corn syrup will be fine. But please check for bugs (look for webs). It's a rare airborne fungus that would be harmful to eat (as opposed to breathe). And bacteria can not live in those things (too dry). Ariel. (talk) 21:11, 1 February 2010 (UTC)

to get to orbit, is the weight of the rocket fuel you need linear with the weight of the payload you get up?

if a trillionaire was inspired by a successful government rocket launch and decided, I wanna get a payload that's ten thousand times heavier up into orbit, would they need a rocket system that is ten thousand times as massive? (ie a linear relationship). Or would it be more/less?

In general, how massive a rocket system (rocket system including fuel) do you need to get x pounds of weight up into orbit? (ie what is the formula).

neitehr is homework question, thanks. 84.153.232.162 (talk) 19:13, 1 February 2010 (UTC)

• Depending on the distance you want to go and the time you have (if a trillonnaire, plenty or none ?), fuel may put you off terrestrial gravity and then you just have to let solar winds or ionic propulsion take the relay with very much less load costs. --82.227.17.30 (talk) 19:25, 1 February 2010 (UTC)

No. See Rocket equation. The reason is that you need to lift (part of) the fuel, too. 95.112.190.236 (talk) 19:30, 1 February 2010 (UTC)

You are wrong. It IS linear with the amount of stuff you want to lift. Here is a thought experiment: Imagine you have a launch vehicle that can get 1 ton up to the required orbit with a certain amount of fuel. Now you want to launch a 1000 ton object. Well, you could cut it up into 1000 one ton pieces and launch each piece using a 1 ton launcher and the cost in fuel and motors would be exactly 1000 times as much as for launching 1 ton. Then, because all of the 1000 rockets are identical and with identical payloads - they would go up at the same speed/acceleration. That means that you could launch them all simultaneously and they would stay together. So you can bolt them all together and pretend that they were just one large rocket - and now you don't have to cut your payload into bits. In reality, there would be some parts such as control circuitry and many redundant systems that would not need to be duplicated 1000 times - so in practice, it's a little better than linear. SteveBaker (talk) 19:58, 1 February 2010 (UTC)

You are right, it is linear from the equation. I got it wrong in memory and was too convinced to read the article I've linked for a check. It probably is not linear with very small weights as the hull weight is not linear (so I think). 95.112.190.236 (talk) 20:23, 1 February 2010 (UTC)

But I would like to hitch-hike the question and add my own: how small (weight and dimensions) can a rocket be to enter near earth orbit from earth? 95.112.190.236 (talk) 19:30, 1 February 2010 (UTC)

Well, our comparison of heavy lift launch systems provides a good starting point. Considering low earth orbit only, here's some common systems and their efficiency (payload over launch mass):

• Atlas V: 5.4%
• Titan IV: 2.3%
• Delta IV: 3.5%
• Ariane 5: 2.7%

Now, of those, the Titan (the least efficient) is also the largest. The Atlas (most efficient) is also the smallest. It's also got a large payload range specified, so I'm more suspicious of that estimate being high. Anyway, we can finally consider the Saturn V, with 3.9% efficiency to LEO, and it's many times larger than any of the above. So basically, economy of scale doesn't apply from a size standpoint. As such, you're probably not going to make one ten-thousand class launcher; instead, you'll launch ten thousand generic ones (or one thousand ten-class launchers, or something else that really will let you use economies of scale). — Lomn 19:32, 1 February 2010 (UTC)

Addressing the rider question: Given the above, you could expect to launch a 1 kg payload to LEO with about 50 kg of rocket, if everything scaled well. 500 kg of rocket should work out fine as a theoretical minimum launch vehicle. Poking through our comparison of small lift launch systems, the British Black Arrow was the smallest actual launch vehicle I saw at 18000kg and 13 m tall. — Lomn 19:40, 1 February 2010 (UTC)

So if you wanted to send something really high, best to use a ballon. Beach drifter (talk) 19:44, 1 February 2010 (UTC)

No - a balloon won't get you above the top of the atmosphere - and it won't get you the orbital speed you need so even if you could get up to the right altitude, the payload would just fall back to earth again. So you still need a rocket or something similar to get you up to orbit. However, a balloon is a great way to get really high without orbiting. SteveBaker (talk) 20:03, 1 February 2010 (UTC)

Er, well, thats why I said really high, and said nothing about orbit. Beach drifter (talk) 20:18, 1 February 2010 (UTC)

Uh me bad for original thinking! I imagine a pipe of glass carbon (what, no article on that? Did I get the spelling wrong?) filled with oxidizing rocket fuel and using the flopping effcet (what, no article???) to throw off burnt parts of the pipe as to emulate multiple stages of a rocket thrown off. And, of course, set off in a high altitude reached using a hydrogen balloon. 95.112.190.236 (talk) 20:07, 1 February 2010 (UTC)

mRNA and secondary structure...

What causes mRNA secondary structure? What impact did the presence of secondary structure in the mRNA have on the scanning and initiation steps of translation? —Preceding unsigned comment added by 137.141.248.112 (talk) 21:12, 1 February 2010 (UTC)

Black Arrow awakened

Is there any reason why, if the engineering plans and other details survive, that a Black Arrow could not simply be built, giving a working launch vehicle with zero development costs? Obviously a launch site would be needed too. 92.29.34.140 (talk) 21:33, 1 February 2010 (UTC)