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December 12

Alcohol's effect on CNS

We all know that alcohol affects the central nervous system slowing down reactions and muscle movements etc but does this mean it also has an effect on involuntary movements such as breathing or heart beats? And I mean in the short term, not long term problems as a result of drinking. And also assuming the person has no log term health problems. 2A02:C7D:B901:CC00:1492:CF54:6C39:5046 (talk) 10:09, 12 December 2015 (UTC)

See Alcohol intoxication#Acute alcohol poisoning. Excessive alcohol consumption can indeed cause fatal respiratory depression. Tevildo (talk) 10:46, 12 December 2015 (UTC)

Methanol is toxic, ethanol, by overdose only. --Hans Haase (有问题吗) 00:21, 15 December 2015 (UTC)

Do insects learn?

We know that cats learn. I mean a very basic thing: we notice that at one time, a cat does something in one way, but later, it chooses to follow a different way to do that very thing. For example, it may learn to recognise certain people, or it may learn how to open doors, or it may learn a certain location that helps achieve certain ends, or it may learn actions to avoid in a certain location or in presence of certain people. We know that cats do the same things differently at different times, based on their unique experience (the point of uniqueness of behaviour is important: for one aspect, since it is impossible to pre-enumerate every possible behaviour, that implies that a change in behaviour corresponds to a real change in the structure of their brains, it doesn't boil down to a mere illusion of observation). Do we know the same, at least in some marginal cases, about insects? Can they learn at least sometimes? Or they never learn at all? I know that questions about consciousness could be debated to no end, but this question is not about consciousness. Thank you. - Evgeniy E. (talk) 10:20, 12 December 2015 (UTC)

We don't have an article specifically on insect learning, but see Ant#Learning and Bee learning and communication. This paper might also be useful. Tevildo (talk) 11:19, 12 December 2015 (UTC)

Thank you, much appreciated. I edited the place where I looked for the answer. - Evgeniy E. (talk) 12:55, 12 December 2015 (UTC)

From those example, you can see that insect "learning" is rather limited, more what we would call memorization, like memorizing the path to food. However, more fundamental learning, like a new language (say used by another species), might well be beyond them. Cats and dogs, on the other hand, are able to learn at least a few words of our language. StuRat (talk) 06:40, 13 December 2015 (UTC)

The essential difference between learning to respond to a certain type of flower (as bees can do) and learning to respond to a certain spoken word (as dogs can do) is not obvious to me. Looie496 (talk) 12:24, 13 December 2015 (UTC)

For a computer programming POV, it's the difference between loading more data into an existing program, like the location of a food source, versus writing a new program, like one to communicate in a new language. For example, an electronic microwave oven has some ability to remember, in that you punch in the temperatures and times for each cycle, and it follows those commands. But you're not going to get a microwave that isn't designed for speech recognition to spontaneously understand you (even if we assume a microphone was attached to it). From a biological POV, remembering a location requires far fewer nerve cells and connections to establish, and falls into the category of "instinct" (the instinct to locate food, remember it's location, and return to that location with others, for example). But to learn something completely novel requires more brain than they have. StuRat (talk) 21:56, 13 December 2015 (UTC)

They do learn - in almost all the ways you mention for a cat. I'm not entirely sure whether you meant the question to relate to invertebrates in general, or limited to insects, so I will stick to insects for the moment. You will find some of their learning abilities described in Pain in invertebrates#Conditioned avoidance and Pain in invertebrates#Cognitive abilities. Drone bees will learn to suppress extending their proboscis when this results in an electric shock. Fruit flies learn to avoid areas that are too warm (like my cats in summer!). Bees are able to form concepts - a method of advanced learning. Both ants and bees show evidence of numeracy (to the best of my knowledge, this has not been shown in cats!).DrChrissy ^(talk) 12:57, 13 December 2015 (UTC)

Thanks for all additional examples. ;) Well, now I actually wonder whether there are massive groups of animals, who have a brain or at least a nervous system, but cannot learn. ;) (In the sense of developing unique behaviour in response to unique experience). But this question, I suppose, is much more difficult to answer. ;) Most likely, this one can't? ;) - Evgeniy E. (talk) 21:08, 13 December 2015 (UTC)

Not really all that difficult a question to answer - but you need to define what a "brain" is.DrChrissy ^(talk) 00:37, 14 December 2015 (UTC)

I could evade this need by relaxing the criteria to "at least a nervous system" and never-minding the level of its complexity. There is a problem, of course, with the fragment of "massive groups", no-one knows what makes a group "massive". ;) I don't know why I was interested in this follow-up question, so now I preferred to not give any additional specification. Anyway, I got what I needed when I asked the original question. ;) (Now I am confused, though: proving absence of learning in different obscure animals should seem impossible; therefore, there ought to be no references to such proofs anywhere in the Internet or beyond; therefore, the question ought to be difficult to answer). Again, thanks everyone who helped. ;) - Evgeniy E. (talk) 01:28, 14 December 2015 (UTC)

Belated response to your closing question 3 posts above: this one apparently can, if you count forming long-lasting memories as 'learning.' {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 18:19, 14 December 2015 (UTC)

Name of physical property when solid object touches water

If you touch a water bubble with a pencil, the water seems to stick to the pencil. How's this stickiness called?--3dcaddy (talk) 19:08, 12 December 2015 (UTC)

I think the answer is "Surface tension". 80.44.164.220 (talk) 19:14, 12 December 2015 (UTC)

No, the answer is Dispersive adhesion. Surface tension is a different phenomenon. There's quite a good explanation of the physics behind what I believe you're looking for at Wetting. ‑ Iridescent 19:16, 12 December 2015 (UTC)

Isn't surface tension different, but pretty close to the dispersive adhesion you cite? You have cohesion, between molecules of the same substance. And you have adhesion, between molecules of the same substance. --3dcaddy (talk) 21:06, 12 December 2015 (UTC)

It's all part of the same suite of phenomena caused by the types of intermolecular forces present; in water this is primarily hydrogen bonding, and the same kinds of processes are also involved in things like meniscus and capillary action. --Jayron32 21:51, 12 December 2015 (UTC)

What is enq in the following context?

I found an exercise in the google: A patient of heart rate of (120/min) his pressure is 150/90 mmHg. Calculate the work done by the left ventricle for 2 seconds.

Sol:-

W= p x ∆V

P= (150+90)/2 = 120 mmHg.

=120 x 1330 = 1.6 x 105 dyne/cm2

∆V = 120/60 sec x 80 ml =160 ml/sec.

W=120 x 1330 x 160 =2.6 x 107erq/sec

W/2sec = (120 x 1330 x 160) x 2=5.2 x 107 erq/sec.

92.249.70.153 (talk) 21:43, 12 December 2015 (UTC)

Looks like a typo for erg. DMacks (talk) 21:49, 12 December 2015 (UTC)

More like a scanno. —Tamfang (talk) 22:27, 12 December 2015 (UTC)

It must be an extremely old article. The erg hasn't been in common use outside astrophysics since about 1960. Tevildo (talk) 23:26, 12 December 2015 (UTC)

Well, just for the exercise: 120 mmHg (average) x 133.322387415 (Pa/mmHg) = 15999 Pa = 15999 N/m² = 15999 kg m^-1 s^-2. Because one dyne = g cm /s², it gets a 10^-5 conversion factor, which then is cancelled by cm² to a 10-fold difference. (It is right around now one remembers that the incursion of CGS units removes much of the vaunted advantage of the so-rational-and-easy-to-work metric system...) Unchanged: ∆V = 2 [beats] / s x 80 ml = 160 ml/s = 0.16 l/s. So W = 15999 Pa x 0.16 l/s = 2560 kg l m^-1 s^-3 ... say waat? ... the assumption, not stated, is that 1 kg = 1 l for blood, so that's 2560 kg² m^-1 s^-3. This is then multiplied by 2 s for 5120 kg² m^-1 s^-2 = 5120 J/s - this is multiplied by (1000 g/kg)²(1 m/100 cm)² for a net 10⁴ conversion factor. And now that I have refreshed my recollection of what I think of cgs, I shall endeavor once more to forget it... Wnt (talk) 15:09, 13 December 2015 (UTC)

When and how Saddam Hussein destroyed his WMD?

It's clear that Saddam had at some point MDWs, but none were found after the Iraq invasion. What happened to his MDW program and arsenal? — Preceding unsigned comment added by Scicurious (talk • contribs) 23:16, 12 December 2015 (UTC)

See United Nations Monitoring, Verification and Inspection Commission and Iraq Survey Group (and weapons of mass destruction, WMD, as well). According to the second article, the survey had "not found evidence that Saddam possessed WMD stocks in 2003". To answer your question, it didn't exist. Tevildo (talk) 23:25, 12 December 2015 (UTC)

That does not answer my question. I am not disputing that there were no MDW weapons in 2003. But what happened to the MDW program between the last use and 2003? Did he use all weapons that were produced? What happened to the factories? Is all buried somewhere? --Scicurious (talk) 23:55, 12 December 2015 (UTC)

WMD conjecture in the aftermath of the 2003 invasion of Iraq summarizes the various conspiracy theories about the issue. The official reports (mentioned above) found no evidence that Saddam had a working chemical weapons programme, so, again, "it didn't exist" is the answer best supported by the evidence rather than speculation. Tevildo (talk) 01:18, 13 December 2015 (UTC)

The conjectures above are rather about the recent events pre-2003. And it might be a fact that in 2003 there were none. I am not disputing this. But it's also a fact that back in the 80s or 90s, he had some, and has even used them. So what happened to the WMD program, stockpile, scientists? I am asking way before Bush + Blair accused Saddam of having WMDs. --Scicurious (talk) 02:41, 13 December 2015 (UTC)

We do have the more general article Iraq and weapons of mass destruction. -- ToE 03:30, 13 December 2015 (UTC)

We found his stockpiles of chemical WMDs used previously. Not sure we found the aluminum tubes used for centrifuges. We had the same evidence of a nuclear program that we have for Iran and North Korea. When the U.S. invaded Iraq, all CIA analysts agreed that he had a nuclear weapons program but disagreed about whether specific components (so-called "dual use" items) were used in the program. This includes Valerie Plame. We see things like chemical weapons used in the Syrian Civil war so they exist. --DHeyward (talk) 03:54, 13 December 2015 (UTC)

Here is a 2005 Report to the President of the United States: The Commission on the Intelligence Capabilities of the United States Regarding Weapons of Mass Destruction. This 600 page book contains over two hundred pages of unclassified, public information about Iraq's purported weapons program - as reported by informed expert witnesses and endorsed by numerous United States senators. The report explains what the Senate commission believed to be factual, with respect to the existence of weapons of mass destruction in Iraq.

Among the many specific statements in this report: chemical weapons facilities did not exist. Evidence of chemical weapons facilities also "did not exist." (Page 121). Biological weapons did not exist. Evidence of biological weapons also "did not exist" - it was "fabricated" (page 80, page 108). The same applies to the nuclear weapons program (page 3); the intelligence analyses of the purported Iraqi program were technically flawed and based on poor intelligence "tradecraft" (page 66); although further details about our Government's ability to conduct nuclear program monitoring are not published because they contain classified information (page 305).

In short, the United States Senate (including Republican senator John McCain) believed that there were no weapons of mass destruction and any evidence of such weapons did not actually exist when President Bush was briefed. Much of the report follows up on these bold assertions with factual data, paper trail investigations; the report outlines proposed motives and other causal factors for these incorrect and false intelligence reports; and makes recommendations for ways to prevent this problem in the future.

If this voluminous information does not satisfy your curiousity, maybe you can rephrase your question. Are you looking for information as reported by some other source? If so, which source?

If you do not believe the (unclassified) factual assertions published by the United States Senate, then whose factual assertions would you rather trust? We can find lots of other resources with lots of other points of view; some other authors believe different facts to be true, and we can point you toward those authors; but at some point, you have to believe somebody, or else resign yourself to a sort of solipsistic ambiguity about all factual information.

Nimur (talk) 04:21, 13 December 2015 (UTC)

Here is one more point of view: Disarming Iraq (2004), by Hans Blix. In this book, Blix (who directed weapons inspections for the United Nations UNMOVIC in Iraq) states: "When our commission was established by a Security Council resolution in December 1999, the Council had recognized that there might still be weapons of mass destruction (WMD) in Iraq, despite the fact that a great deal of disarmament had been accomplished through UN inspections after the end of the Gulf War in 1991. In November 2002, a new round of inspections had been initiated to resolve key remaining tasks in the disarming of Iraq."

UNMOVIC was tasked to oversee Security Council Resolution 687, and its successor Security Council Resolution 1284. This called for Iraq to unconditionally accept the destruction, removal, or rendering harmless, under international supervision, of specific weapons. UNMOVIC actually reported that Iraq was largely in compliance with these resolutions, and there were specific action-items that were called out for escalation. The State Department reported that UNMOVIC reported that Iraq was not in compliance. Depending on whose report you read, you get a different portrayal of the facts, which is exactly what the problem was. The factual evidence was not presented to decision-makers, and consumers of factual information did not closely and critically scrutinize the facts. (Perhaps, as the Senate report I linked above alleges, the decision-makers did not want to be fully-informed). Quoting Blix: "The military invasion of Iraq was all but announced and here we were at the UN sketching a peaceful way to try to ensure the country’s disarmament!"

Nimur (talk) 05:20, 13 December 2015 (UTC)

Some people missed the point of the Q, that at one time there was no question that Saddam had WMD's, he even dropped poison gas on a Kurdish village (Halabja chemical attack). Then, by the US invasion of Iraq, they had apparently all disappeared. The "expert speculation" I heard was that he had them destroyed, to comply with the UN, but did it in secret, so as to keep his enemies, such as Iran, guessing. StuRat (talk) 05:42, 13 December 2015 (UTC)

I believe I saw somewhere that he got rid of then between 1991 and 1993 just after the Gulf War. Sorry I have to do other things and can't look i up. Dmcq (talk) 09:57, 13 December 2015 (UTC)

StuRat DMCQ got exactly the point of my question.

I don't know why others insist on the 2003 situation. I have no doubt there were none on 2003. And although it's interesting to see it confirmed with sources, the question is about what happened (to the factories and stockpile) between the documented use of the WMDs, and, the documented confirmation there were no WMDs anymore. --Scicurious (talk) 13:09, 13 December 2015 (UTC)

Maybe you are choosing not to read the resources I linked; the UN monitored and documented the disarmament subsequent to the 1991 Gulf War, and they published all their reports. The UN continued to monitor and document to ensure that new activities in Iraq did not violate the agreed-upon rules. The process was difficult and not always conducted on friendly terms, but it did take place, and the UN published details extensively. (UNSCOM document archive; UNMOVIC document archive). This stuff is free and available on the internet: you don't need special connections or privileges to see it; you don't need to file paperwork with your government representative to review the bulk of the documentation; it is largely unclassified and available for you to inspect (you don't need any "Internet Activists" to leak it to you). For example, here are a random assortment of official press photos of equipment being destroyed or removed during UNSCOM inspections in the early 1990s. Here's one dramatic photo that is easy for a non-technical reader to understand, specifically of UNSCOM watching 122mm rockets being burned. Everything is published for you to independently review and evaluate. With which part of this extensive documentation are you misunderstanding or disagreeing, or just choosing not to look at?

I can only assume that your braindead refusal to look at these facts is part of your political agenda to ignore facts. This specific problem of intentionally ignoring documented reality has been a historical problem and you are perpetuating a distortion of fact that significantly contributed to the casus belli in 2003.

Perhaps, if encyclopedic sources are too dense for you, you will understand a little better after considering Aaron McGruder's lampooning of the situation from the Boondocks series episode, "A Date With The Health Inspector".

Nimur (talk) 18:34, 13 December 2015 (UTC)

Maybe you are choosing to ignore the maning of the word 'hidden'. Hidden means they cannot be found, otherwise it's not hidden. That's why the UN could find all the weapons. That does not mean Saddam didn't keep some. --Scicurious (talk) 19:57, 13 December 2015 (UTC)

You are essentially parroting the argument put forward by Defense Secretary Donald Rumsfeld. If you are doing this in an intentional fashion, for the sake of playing the apologist, your position has the disadvantage that the present year is 2015, and his argument has been discredited by more than ten years full of new factual information. If you are parroting his argument simply because you are uninformed, you might wish to read some more history. In either case, unless you are asking for scientific references on this topic, this discussion probably does not belong on the Science Reference Desk. Nimur (talk) 20:40, 13 December 2015 (UTC)

To put things a different way, your last comment is very confusing. You initially wanted to know what happened to those WMD which did exist in 1991 and before, to 2003 when they did not exist. While some of the above answers may have been offtopic; even if you didn't initially understand Nimur's answer, the second version of the made it clear that their sources did provide an answer to your question of what happened to those weapons that did exist.

You now bring up "hidden" weapons. Are you trying to ask when the hidden weapons were destroyed? If you are asking this, what evidence do you have for these hidden weapons?

Are you trying to say there were still weapons in 2003 and although these were never found they did exist and were simply hidden? If so, not only do are you coming up with a conspiracy theory apparently without support, your complaints about any of the older answers now seem unfair since these answers did address this claim, even if it hadn't yet been made.

Are you trying to say that the suggestion there were WMD in 2003 wasn't inaccurate at the time since there may have been hidden WMD? If so, again you'll need to provide some refs for the suggestion there was good reason to believe he may have hidden WMD (which would need to be more than Saddam was perfectly willing to do something like that). As again the evidence from sources thus far, particularly from Nimur but also others (again including some of those you complained about) suggests there was no good reason to believe there was a hidden program in 2003.

Nil Einne (talk) 04:24, 14 December 2015 (UTC)

There are two questions: Did he have WMDs? followed by Did he have a WMD program? It is easy to conflate those two questions. The same would be true for Iran, Pakistan, North Korea, Israel, South Africa, etc, etc. While the existence of actual WMDs was circumspect with many doubters, the belief that he had a program was not. Virtually everyone believed he was developing WMDs and that is in the Senate report. It was the reason Clinton bombed him and Valerie Plame even believed he had a WMD program. CIA analysts disagreed on specifics like yellow cake and aluminum tube but not the overall assessment that Iraq was trying to obtain and build WMDs in violation of the UN sanctions. --DHeyward (talk) 05:32, 14 December 2015 (UTC)

The later question seems irrelevant to anything discussed in this thread (note the OP said hidden WMD, not hidden WMD programme) so not sure why you want to take it even more offtopic. Of course what people may or may not have believed because "Collectors and analysts too readily accepted any evidence that supported their theory that Iraq .... was developing weapons programs, and they explained away or simply disregarded evidence that pointed in the other direction" or whatever also seems less important that what the evidence now suggests was really going on, but again this all seems terribly off topic. Edit: I see the OP did mention something about a MWD (sic) program in some earlier comments. But their question was what happened to it, not what people may or may not have believed happened to it in 2003, so your comment still remains off-topic. Also they seem more interested in the actually WMD stockpile and why few or no more were produced, rather than the a WMD program in the theoretical sense. Nil Einne (talk) 13:28, 14 December 2015 (UTC)

DMCQ above is correct. The short answer to the OP's question is in Hussein Kamel al-Majid's 1995 statement- "I ordered destruction of all chemical weapons. All weapons—biological, chemical, missile, nuclear—were destroyed." There was not much real doubt after that that Iraq did not have WMDs.John Z (talk) 02:24, 15 December 2015 (UTC)

December 13

Leadership skills

Does volunteering with listening services such as befriended or Samaritans teach you leadership skills? — Preceding unsigned comment added by 2A02:C7D:B901:CC00:7CE7:1D53:9581:45DA (talk) 09:30, 13 December 2015 (UTC)

It can do, much depends on the role you undertake as a volunteer and how you use your time there. --TammyMoet (talk) 10:06, 13 December 2015 (UTC)

For those unfamiliar with the organizations, we have: Samaritans (charity) & Befrienders Worldwide. -- ToE 14:32, 13 December 2015 (UTC)

Why can ethanol be used as a rocket fuel but gasoline can't?

^Topic ScienceApe (talk) 16:51, 13 December 2015 (UTC)

Kerosene has been used as a rocket fuel. I imagine it was preferred over gasoline because it is safer to work with and used to be cheaper. Jc3s5h (talk) 16:56, 13 December 2015 (UTC)

Gasoline _can_ be used as a rocket fuel - Robert Goddard's first liquid-fuelled rocket, "Nell" (1926), ran on gasoline and liquid oxygen. See RP-1 for our article on hydrocarbon rocket fuels - apparently, OTRAG, a 1980's German hobbyist organization, built a rocket that ran on diesel. Tevildo (talk) 18:33, 13 December 2015 (UTC)

The article says the fuel is, "The fuel was intended to be kerosene with a 50/50 mixture of nitric acid and dinitrogen tetroxide as an oxidiser." ScienceApe (talk) 19:09, 13 December 2015 (UTC)

This article (New Scientist, May 1976) states that the prototypes, at least, were diesel-powered. This site has a list of (presumably theoretical) specifications, which include the use of diesel fuel. Tevildo (talk) 20:04, 13 December 2015 (UTC)

This is more of an educated guess than a factual one but based on the characteristics of gasoline. Firstly, consider starting. Have you noticed that just before a LOX kerosene engine starts, little pyrotechnics come on to shower the exhaust nozzle with sparks to ignite the fuel. Imagine using petrol – it is explosive. It could easily over pressure the combustion chamber and blow it apart – or in astronautical terms, cause it to under go rapid disassembly. Say all engines do successfully fire up – what then. Gasoline does not burn smoothly. Both kerosene and alcohol have a lower octane rating... they want to burn as soon as they get hot enough in the presence of an oxidizer. The fuel to air/oxidizer ratio is less important. Petrol on the other hand may pause a moment and think about whether it wants to oxidise and having finally decided to oxidize.... it-can-do-so-sudden. So such an engine running on petrol will not run smoothly. It with stutter and cough. Should it burp in the process, the combustion chambers could well scatter bit of themselves all over the place. To run a petrol rocket engine one needs to run it very rich (i.e., much less fuel than the optimum amount of oxidizer and that lead to a lower SI). Even modern hydrogen/LOX engine are run a little fuel rich. Better to waste a bit of fuel than waste a whole rocket.--Aspro (talk) 18:57, 13 December 2015 (UTC)

 ? Nimur (talk) 19:08, 13 December 2015 (UTC)

Page five:
One odd aspect of Goddard's early work with gasoline and oxygen is the very low oxidizer-to-fuel ratio that he employed. For every pound of gasoline he burned, he burned about 1.3 or 1.4 pounds of oxygen, when three pounds of oxygen would have been closer to the optimum. As a result, his motors performed very poorly, and seldom achieved a specific impulse of more than 170 seconds.

Page 20

Malina and company started experimental work with RFNA and gasoline as early as 1941—and immediately ran into trouble. This is an extraordinarily recalcitrant combination, beautifully designed to drive any experimenter out of his mind. In the first place, it's almost impossible to get it started. JPL was using a spark plug for ignition, and more often than not, getting an explosion rather than the smooth start that they were looking for. And when they did get it going, the motor would cough, chug, scream and hiccup —and then usually blow anyway.

Ref: [1]

Yeah meant flame front propergation velocity not octane. Yeh got lean and rich mixed back to front too.--Aspro (talk) 22:51, 13 December 2015 (UTC)

Ethanol and especially methanol has a higher octane rating, not lower and less fuel would be lean not rich. Sagittarian Milky Way (talk) 19:40, 13 December 2015 (UTC)

@Aspro: It sounds as if your "just before a LOX kerosene engine starts, little pyrotechnics come on to shower the exhaust nozzle with sparks to ignite the fuel" is describing the Radial Outward Firing Initiators (ROFIs) used to burn off excess gaseous hydrogen during the start of LOX/LH2 engines, such as those used on the Space Shuttle, Delta IV, and SLS. Here is an NSF article discussing their operation. See Rocket engine#Ignition for a discussion of the ignition process. ROFIs are not used for engine ignition, and having the engine lit from an external source like that would result in a hard start. -- ToE 13:59, 14 December 2015 (UTC)

I'm highly skeptical that NASA rocket scientists can't figure out how to keep a gasoline rocket from exploding. I mean, the Nazis could play with hydrazine and concentrated hydrogen peroxide, and they're supposed to be dumb, right? I do note that kerosene has more energy per volume than gasoline [2] - 135 vs 125 kBTU/gal according to this. Then again, several grades of fuel oil have even more, but maybe NASA scientists couldn't... then again, there's also the matter of density... I'm seeing a figure of 0.71-0.77 for gasoline and 0.78-0.81 for kerosene ... thrills. I have no idea how that comes out, too much fog in the numbers, but fuel oil is 0.99-1.01, so that probably is out? Then again, the density also controls how big the rocket needs to be, which is also really important, so... well, at this point I admit I'm not a rocket scientist. Wnt (talk) 21:58, 13 December 2015 (UTC)

Aspro's reference is worth looking at. It's _possible_ to start a gasoline-fuelled rocket without it exploding - it's _much easier_ to start a kerosene-fuelled rocket. It's even easier to start a rocket with hypergolic fuel, but the cost of the fuel would be prohibitive for an orbital booster stage (as opposed to a short-range atmospheric vehicle, like the Me-163). I don't know how RP-1 compares in cost with a hypothetical rocket-rated gasoline blend, but I can't imagine it's significantly more expensive. Tevildo (talk) 23:15, 13 December 2015 (UTC)

Cost of fuel isn't the main thing against hypergolics (though they are more expensive), it's the poor isp. I assume you are aware that there are a number of hypergolic booster still flying (Proton, Long March), so cost isn't 'prohibitive'? That, and safety issues. Fgf10 (talk) 14:27, 14 December 2015 (UTC)

BTU's "per gallon" would be the wrong metric. "Per pound," though is a different story. Kerosene is about 7 pounds per gallon while gasoline is 6 pounds per gallon so gasoline would be a better weight to energy tradeoff though not a volume to energy tradeoff. I would think the problem would relate to compression with an oxidizer present. Kerosene in turbine engines behaves nicely. Gasoline engines have spark plugs because it does not behave well. Higher compression engines need purer gasoline to retard the spark as do piston aircraft but they never rely on compression itself as the igniter (so called "knocking" is bad). A rocket motor compressor would suffer the same problems I would think. --DHeyward (talk) 05:50, 14 December 2015 (UTC)

How do waves and winds interact?

Is there a science dedicated to the interaction of winds and waves on oceans or another big mass of water?--Denidi (talk) 19:55, 13 December 2015 (UTC)

There is - see Wind wave. Tevildo (talk) 20:12, 13 December 2015 (UTC)

Also note that waves formed in other ways, like tidal bores, tsunamis, and boat bow waves and wakes, may be affected by wind after formation, especially at the peaks. StuRat (talk) 23:16, 13 December 2015 (UTC)

Hydrology - "the scientific study of the movement, distribution, and quality of water on Earth and other planets"; hydrometeorology - "a branch of meteorology and hydrology that studies the transfer of water and energy between the land surface and the lower atmosphere". Gandalf61 (talk) 12:03, 14 December 2015 (UTC)

If you google the definition of either of those they are not really specific to waves. Hydrology is to do with the movement of water through land to the atmosphere[3] and hydrometeorology is to do with water in the atmosphere and its effects on the weather.[4] Physical oceanography and fluid dynamics (see Boussinesq approximation (water waves)) are the branches of science that would deal with to the processes of wave formation. Richerman (talk) 14:37, 14 December 2015 (UTC)

December 14

Were coalition troops prepared for/expecting an attack with chemical/biological weapons?

The question above made me curious about what the governments knew in 2003. Officially, the governments claimed there were MD weapons, but did they act coherently to this official position? During the invasion, were coalition troops provided with materiel to protect themselves against a chemical/biological attack? --Denidi (talk) 13:25, 14 December 2015 (UTC)

Yes: "Allied troops then invaded Iraq, taking great precautions in case chemical weapons were used against them." From Medical Aspects of Chemical Warfare, The Surgeon General Department of the Army, United States of America (p. 66). Alansplodge (talk) 14:06, 14 December 2015 (UTC)

In this particular case we can work out which you're talking about because you mentioned the year, but you do really need to give more details. Which government are you talking about? There were four countries involved in the initial invasion, and there was the Iraqi government on the other side. The poster above assumed you are talking about the US government, is this the case? Fgf10 (talk) 14:23, 14 December 2015 (UTC)

UK troops would also be of interest. The other two countries, Australia and Poland, sent only token troops.

The Australian contribution was small, but I wouldn't say it was only token. According to Australian contribution to the 2003 invasion of Iraq#The scale of the Australian force commitment, their contribution was 2.42% of (I think active duty) military personnel compared to 4.85% for the US. This is only slightly under half of the US, and it's difficult to argue the US contribution was close to token. Or to put it a different way, even if the US had only contributed 73,000, it would still be difficult to argue it was token. The relative size of the contribution by Australia was tiny but that's because Australia has a much smaller military, partially because they have a much smaller population. Post invasion, the Australian contribution was somewhat minor compared to the contribution from the US and others so could probably be called token, but your comments seem to be referring to the invasion only. Nil Einne (talk) 19:53, 14 December 2015 (UTC)

The United States military very much operated as if the threat from chemical or other unconventional weapons was real. This included provision of training and materiel, as well as operational, organizational, and doctrinal changes.

From the collection at United States Army's Combined Arms Research Library at Fort Leavenworth:

On Point : the United States Army in Operation Iraqi Freedom, by Col. Greg Fontenot et al., has extensive discussion of NBC preparations during the invasion. For example, Countering Iraqi WMD And Ballistic Missile Strikes (pg. 171) discusses plans and operations. In addition to lots of doctrine and organizational information, there are also anecdotes so you can see what "preparation" meant to ordinary front-line soldiers:

"On 28 March 2003, the platoon was in a blocking position near the “Airfield.” Both Horner and Jackson had just awakened and were eating MREs in the back of the company’s cargo truck. The unit received artillery fire, and an adjacent chemical unit’s alarms went off. It also received warning to don protective overgarments and masks immediately. As their masks had been destroyed [in the vehicle fire], their squad leader (Staff Sergeant Carver) had them run to the back of one of the M2s to have some protection. He also had them pull the hoods of the NBC suit as tightly as possible over their heads. By this time the entire company, as well as the chemical unit, was in MOPP 4."

On Point II : transition to the new campaign : the United States Army in Operation Iraqi Freedom, May 2003-January 2005, by Donald Wright and Col. Timothy Reese:

"Reorganization to meet the campaign’s requirements often meant huge growth in the number of commands under divisional authority. At one point, 1st AD added the 937th Engineer Group and the 18th Military Police Brigade, giving it the equivalent of 9 maneuver brigades and almost 39,000 Soldiers. The division accepted further reinforcements, such as a CA brigade, a chemical company, PSYOP companies, and an aeromedical evacuation detachment. Every division in theater underwent its own version of organizational transition as they rapidly adapted to the requirements of the new campaign in Iraq."

Prior to Operation Iraqi Freedom, an ordinary Army division would not normally include a chemical warfare company. This book also contains a photograph of U.S. Army chemical warfare soldiers preparing and reconditioning their equipment in Iraq, to keep it battle-ready.

Even outside of chemical warfare companies, ordinary troops were issued NBC suits. I am not sure if these were universally issued to all American soldiers.

Nimur (talk) 15:28, 14 December 2015 (UTC)

There was a bit of a rumpus when it was discovered that the British Army didn't have enough NBC equipment for everybody; see BBC News - UK troops 'left without key kit' (2003). I'm certain that the intention was for everybody to be protected, but as usual, it didn't go to plan. Alansplodge (talk) 16:32, 14 December 2015 (UTC)

Measuring the mass of non-detected dark matter

This source and our article Large Underground Xenon experiment both give the impression that, by failing to detect even a single dark matter collision, the experiment can place constraints on the mass that dark matter WIMPs must have. But how can anyone predict the likelihood that a WIMP with a given mass will interact with a xenon atom, never having seen one? Wnt (talk) 18:16, 14 December 2015 (UTC)

The weak interaction is fairly well understood, and predictions can be made about the statistical probability of a particle with specific properties (like the Lightest Supersymmetric Particle) interacting with bulk matter. Although absence of evidence is not evidence of absence, the lack of a single observed collision provides strong evidence that the particular predicted particle is not common (and hence that the whole theory might need re-thinking). Dbfirs 18:44, 14 December 2015 (UTC)

The article glosses over what exactly it is they are able to rule out. It's not really a range of masses, but a region in the 2D plane of mass and scattering cross-section. Other experiments had seen events that could be interpreted as a possible detection at low mass and a particular range of cross-sections. LUX was able to exclude those detection regions. You can see the exclusion region in Fig. 3 of the new paper. A different view, zoomed in on a low-mass region, including some other experiments' possible detection regions, and using older limits, is in the third figure here. --Amble (talk) 21:41, 14 December 2015 (UTC)

Bowel Movements

Do individuals hooked up to nutritional IV long term still have bowel movements. Additionally, if a person had their entire digestive system removed including colon, and they were kept alive with the nutritional IV would they still need to excrete, some how? — Preceding unsigned comment added by 24.215.64.134 (talk) 18:53, 14 December 2015 (UTC)

Despite lacking food, the body still produces matter to excrete as it breaks down red blood cells. In cases where the intestine is either removed or bypassed, the gut is attached to the skin and an opening is produced called a stoma, through which the matter is excreted. See for example ileostomy. --TammyMoet (talk) 19:39, 14 December 2015 (UTC)

[ec] See Parenteral nutrition and this factsheet from the NHS. According to the latter, "[t]he bowel will still produce mucus, cells and bacteria even though food is not being eaten and so you are likely to still have a bowel movement". I don't know of any surgical procedure that involves removing the _entire_ digestive system (from the oesophagus to the anus) which the patient is expected to survive; any remaining part of the digestive tract (after, for example, colectomy) will still produce some mucus which will need to go somewhere. Tevildo (talk) 19:45, 14 December 2015 (UTC)

I should add that, as if biology were determined to defeat our pretensions of simple causal logic, babies produce meconium before they ever eat. Wnt (talk) 16:18, 15 December 2015 (UTC)

It's not really the case that they don't eat...they swallow amniotic fluid in the womb. You try floating in something for nine months and not swallowing any of it. Of course, there isn't much nutrition to be had from it. --71.119.131.184 (talk) 23:48, 15 December 2015 (UTC)

Poorly designed battery: fire by discharging?

Can a poorly designed Li-ion battery catch fire by discharging too fast? Or, could another problem arise, like smoke or leaks?--3dcaddy (talk) 23:25, 14 December 2015 (UTC)

Yes. It can overheat, damage the separator between anode and cathode, cause a short-circuit, and explode. This is a situation known as thermal runaway.--Denidi (talk) 02:20, 15 December 2015 (UTC)

I'm actually not sure that "poor design" has anything to do with it. If you include "shorting them out" within the definition of "discharging too fast" then almost certainly you will see smoke and possibly fire. I've "disposed" of several such batteries by shorting them out, after they've out lived their useful life, and they've all been varying degrees of spectacular. Vespine (talk) 04:48, 15 December 2015 (UTC)

Indeed, for short-circuiting it, you won't need to be discharging, nor it is related to discharging. That's also why the FAA regulates how batteries can be carried by passengers. But I meant it as a process. When you are discharging the battery it can overheat > damage the membrane > short-circuit internally (=>more heat) > fire/explode. --Denidi (talk) 15:20, 15 December 2015 (UTC)

Gravity trains and the rotation of the earth

I was thinking about Gravity trains and realized that when you enter the train you are rotating one way, but when you exit you are rotating the opposite direction. That means that the entire trip would be spent with the train pressed first against one side of the hole and then the other, with an acceleration of about .04g, rather than, as said in the article: "During this entire trip, the train (and all passengers) would be practically weightless.". Am I correct? The article makes no mention of this at all. Ariel. (talk) 23:27, 14 December 2015 (UTC)

Indeed, you need to consider two factors: the coriolis force and the conservation of angular momentum, both of which considerably complicate the mathematical treatment of the trajectory. Although the first simplistic approximation you learn (by application of Gauss's law for gravity) is that the object in the hole is a "simple harmonic oscillator," the trajectory is in actual fact that an orbit through a non-uniform gravitational field.

I think there is a homework problem on this issue in Marion and Thornton, but I don't recall if they work the solution. I can check later today.

Nimur (talk) 23:47, 14 December 2015 (UTC)

The "tunnel through the Earth" oscillator was in fact Homework Problem 5-15, in the fifth edition, but it does not actually ask about the rotational effects. However, several problems in Chapter 10 (on rotating reference-frames) ask for re-calculation of earlier chapters' homeworks assuming a rotating Earth. If you can follow the math in these two chapters, you can correctly answer your question about the gravity-train. The calculus is non-trivial - there are a lot of vector cross-products in the equations - but as you intuitively guessed, there will be a non-vertical force that should not be neglected. Nimur (talk) 03:45, 15 December 2015 (UTC)

The tunnel could be dug with the curved path taken into account, allowing zero gee - specifically, you could emerge 42.2 minutes of rotation west of the antipodal point, which is to say 42 / (60*24) * 360 = 10.5 degrees. However, of course, that means that a reverse trip would either have double the acceleration, or have to use a whole different tunnel that ends up 21 degrees west of the original... Wnt (talk) 04:03, 15 December 2015 (UTC)

December 15

finding the work according to the blood pressure and the heart rate

I found on Facebook (later I found the same question -with the same typo- that looks like a source on Google) a very nice question and I decided to take advantage and to try to understand it. But before I'm going to do that, I would like to know if the answer (I found it also there) is correct or not. Afterward, I would like to understand where did the number 1300 come from to the solution. This is the question and the answer:

The pumping action takes place in less than 1/3 cardiac cycle while the heart muscle rests for over than 2/3 of the cycle .
Ex: - A patient of heart rate of (120/min) his pressure is 150/90 mmHg. Calculate the work done by the left ventricle for 2 seconds.
Sol:- W= p x ∆V
P= (150+90)/2 = 120 mmHg.
=120 x 1330 = 1.6 x 10⁵ dyne/cm²
∆V = 120/60 sec x 80 ml =160 ml/sec.
W=120 x 1330 x 160 =2.6 x 10⁷erg/sec
W/2sec = (120 x 1330 x 160) x 2=5.2 x 10⁷ erg/sec.
— Preceding unsigned comment added by 92.249.70.153 (talk) 00:01, 15 December 2015 (UTC)

Regarding the 1330 used in the solution (I assume that is the 1300 you are asking about), see millimeter of mercury (and Torr, which is essentially the same thing). 1 mmHg ≈ 133.3 Pa (where Pa is the unit of pressure Pascal). But your example problem appears to work with CGS derived units, where 1 barye (symbol: Ba) = 1 dyne per square centimeter = 0.1 Pa. So 1 mmHg ≈ 1333 Ba. Presumably the students were told to use the approximation 1 mmHg ≈ 1330 dyne/cm². -- ToE 03:46, 15 December 2015 (UTC) (I added linebreaks to the original question and repaired the exponential notation for readability.)

Regarding the problem itself, an unstated assumption is that the volume pumped each beat is 80 ml.

Also assumed is that the pressure increase imparted by the left ventricle is equal to the average of the systolic and diastolic pressures. This doesn't seem to account for the inlet pressure coming from left atrium, but perhaps that is insignificant.

Given those assumptions, calculating pumping power is easy, but their solution is sloppy with its units and confusion of work and power.

The work done on the fluid by a single stroke of a reciprocating pump is W = ∆p x ∆V (change in pressure times the volume displaced) and the average power of the pump is P = ∆p x Q (change in pressure times the volume flow rate).

So if your pressure increase really is equal to the average of the systolic and diastolic pressures, then yes, ∆p = 120 mmHg (133 Pa / mmHg) ≈ 1.6x10⁴ Pa (or 1.6x10⁵ Ba).

∆V = 80 ml, so the work done each beat is 1.6x10⁴ Pa x 8.0x10^-5 m³ = 1.3 J (or 1.3x10⁷ erg).

At 120 bpm, there are four beats in two seconds, so the total work done during that time is 4 x 1.3 J = 5.2 J (or 5.2x10⁷ erg).

Or, doing it their way, the average flow rate Q (not ∆V) is indeed 160 ml/sec. And the average power P (not W) is indeed 1.6x10⁴ Pa x 1.6x10^-4 m³/s = 2.6 J/s (or 2.6x10⁷ erg/s).

Thus the work done over two seconds is P x 2 s = 2.6 J/s x 2 s = 5.2 J (or 5.2x10⁷ erg).

Working CGS and getting your answer in erg saves you having to convert 1 ml = 1x10^-6 m³, but at the scale of this problem Joules seem more appropriate than erg. (You should pick up from context what units are expected in the particular field, though this may change over time.)

So their solution was particularly sloppy, and while their final numerical answer was correct, the units of that answer should have been erg (units of work) and not erg/s (units of power). If you make $10/hr, how much money have you earned after working 4 hours? $40, right, not $40/hr. -- ToE 15:37, 15 December 2015 (UTC)

A medium-size object

If the biggest thing is the universe and the smallest thing is a quark (or something like that), then how big is an object that is half way between? Does this question make any sense? Anna Frodesiak (talk) 00:07, 15 December 2015 (UTC)

We have an article, Orders of magnitude (length). The way you have phrased your question is a little bit difficult to answer - the question is valid English syntax, but it's not really the way physicists describe or compare sizes. You are not entirely correct in asserting that a quark is the smallest object we know about; nor in the implication that the universe is a single object. These details entirely depend on how you define "object," and subsequently how you choose to measure or define the size of an object. Universes and quarks are different types of entities, so it's strange to compare them; but we can use characteristic length scales to compare different types of objects. Finally, it's not clear how you want to measure "half way between" different length scales - we could use the arithmetic mean or the geometric mean; or we could look at some kind of logarithmic scale; and so on.

Nimur (talk) 00:18, 15 December 2015 (UTC)

Okay, I'm reading Orders of magnitude (length) and it sort of clears stuff up. I guess it is hard to ask such a question.

Anyhow, I'm pretty sure that if the observable universe sat down in a restaurant with a neutrino, the known universe would order a lot and the neutrino would probably have the small salad. Anna Frodesiak (talk) 00:31, 15 December 2015 (UTC)

But the universe would have to cover the check, because the neutrino has no charge. *groan* --71.119.131.184 (talk) 01:50, 15 December 2015 (UTC)

I suspect that joke was invented within a day or two of the neutrino's discovery. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:23, 16 December 2015 (UTC)

See the "Visualization" section under Planck length; you could sort of make the argument from that that it's a period. Wnt (talk) 03:35, 15 December 2015 (UTC)

Very nice, Wnt! Now that is something I can grasp. Many thanks. :) Anna Frodesiak (talk) 05:44, 15 December 2015 (UTC)

Anna Frodesiak, I have a clear memory of being stunned by the short documentary film Powers of Ten (film) (1968) when I first saw it as a college student in the 1970s. It makes the case that the realm of things that humans see and deal with every day is at the halfway point on the scale. Highly recommended. Cullen³²⁸ Let's discuss it 07:17, 15 December 2015 (UTC)

Thank you, Cullen328! I just watched it. I found it in my archives and actually remember watching it years ago. It is very good. Many thanks. :) Anna Frodesiak (talk) 08:04, 15 December 2015 (UTC)

The concept of "half way between" is not clearly defined. The arithmetic mean would be an object about half the size of the universe (if we could define such an object). The orders of magnitude approach leads to the Geometric mean, but there are other possibilities. Dbfirs 10:32, 15 December 2015 (UTC)

Does the universe really qualify as an "object"? However, if X represents the number of objects within that universe, then halfway would be approximately X / 2. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:38, 15 December 2015 (UTC)

You mean the size of the middle object when all objects are arranged in order of size? That would be the median which, I guess would be much smaller than the geometric mean ... probably around the size of a proton a neutrino since there are at least a million neutrinos for every proton. Dbfirs 17:24, 15 December 2015 (UTC)

No, I mean the size of half the total matter + energy in the universe. As to what the OP means, that's not altogether certain. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:34, 16 December 2015 (UTC)

I agree that half the total matter would be half the size. Usually, counting objects leads to the median, but we don't know what "objects" we are supposed to be counting here. Dbfirs 08:23, 16 December 2015 (UTC)

• Miss Frodesiak^* is clearly asking about the geometrical mean, as Dbfirs has pointed out, and the movie and later book editions of Powers of 10, which Cullen mentions, demonstrate graphically that everyday objects lie around that mean. See YouTube μηδείς (talk) 17:13, 15 December 2015 (UTC) ^*Of no relation to the Passyunk Avenue Frodesiaks

This stands or falls on the definition of an "object". It's arguable that the universe isn't "an" object - but rather a collection of objects. Sadly, the same could be said of a rock or an atom or even of a proton. If you allow a "collection" to be an object - then should we consider the collection of all of the people named "Steve" to be "an object"? If not, then calling the universe "an object" seems wrong...but if you do include collections, then should we consider "The set of all people named 'Steve' who were born under a full moon" to be a different object than the larger set of all people named "Steve"? If the answer to that is "Yes" then we can count "Everything in the universe made of hydrogen" to be "an object" - which is nearly as big as the entire universe.

Worse still, it's perfectly possible that the universe is infinite - in which case, the thing that's halfway between its' size and that of a quark is still infinite.

So you need a stronger definition. You can ask "What is the tallest mountain?" and we stand a good chance of getting you an answer - but "object" is just too vague. SteveBaker (talk) 21:21, 15 December 2015 (UTC)

If you look at time however the human lifetime is quite large, and the total time of life is a large fraction of the age of the universe so far. Graeme Bartlett (talk) 21:14, 15 December 2015 (UTC)

I am referring to the geometrical mean. And when referring to the universe as an "object", just pretend it is a big ball the size of the universe. Anyhow, "everyday object"? Wow. Isn't that like standing on an ink dot and saying that the entire universe is inside? That seems odd to me. From my person-size viewpoint, big seems bigger than small seems small. Anna Frodesiak (talk) 00:51, 16 December 2015 (UTC)

You're criticizing the responders, but you have yet to define what you mean by "object". Is the earth an "object"? Is the sun an "object"? Is a galaxy an "object"? Is a given cluster of galaxies an "object"? Also, geometric mean of what? ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:39, 16 December 2015 (UTC)

Criticizing? Good heaven, no. I'm enormously grateful and just asking. I should have phrased it better. You see, this is why I always salt and pepper my posts with lots of smileys. :) It is so hard to judge tone. When I say "...Anyhow, "everyday object"? Wow. Isn't that...", I mean, really, wow. It is so cool that an everyday object is the "mean". And when I say "mean", as others have said above, I mean "mean" as in the middle or average sort of thing. I'm not even sure if that can be a thing considering it kind of means that half the objects are bigger and half smaller. I'm not too good at maths. :) With sincerity, plenty of smiles, gratefulness, humility, and deference to be sure, I would never criticize responses here. I am not qualified to do so. Best, Anna Frodesiak (talk) 08:41, 16 December 2015 (UTC)

Anna Frodesiak, perhaps you can't imagine just how small the elementary particles really are? We can't see the millions of bacteria on our skin, but these are enormous on an atomic scale. Dbfirs 08:29, 16 December 2015 (UTC)

Absolutely right! I just can't get my head around the very small. I can feel the magnitude when I think of the universe, but with the very small, I just can't imagine it. I think, for me, this is all about perception. For me, a universe inside a dot of ink is inconceivable. :) Anna Frodesiak (talk) 08:41, 16 December 2015 (UTC)

All is well, except you did not answer my question. For example, is the earth an "object"? ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:00, 16 December 2015 (UTC)

An object is some physical object like a tangerine or planet or bunch of grapes or sure, a galaxy -- anything that is or can represent a particular size. :) I'm really looking for that cubic volume that is between the things with the biggest and smallest cubic volumes. Anna Frodesiak (talk) 11:56, 16 December 2015 (UTC)

So the earth itself is an object, and the solar system is an object (which contains the earth) and the Milky Way galaxy is an object (which contains the earth), and the cluster of nearby galaxies is an object (which contains the earth), and the universe itself is an object (which contains the earth). So the earth is being counted multiple times. What does that do to the mean calculation? ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:17, 16 December 2015 (UTC)

This might be a better example. Consider the state of Florida and pretend it's the universe. Consider one specific orange growing somewhere in Florida, and pretend it's the smallest object in that "universe". So there are multiple oranges on the tree, multiple trees in the grove, and multiple groves in Florida. What would be the mean, under your scenario? ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:23, 16 December 2015 (UTC)

Good question. I don't know. Maybe a mountain? How about an ant as the smallest animal and an elephant as the biggest. I'd say a cat would be the mean. Anna Frodesiak (talk) 13:22, 16 December 2015 (UTC)

high blood pressure/donating blood

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page.

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page. --~~~~

The reference desk will not answer, and will remove, requests for medical advice. Nimur (talk) 00:49, 15 December 2015 (UTC)

We cannot diagnose the OP, but it does no harm to point out that cannabis is a drug, and effects of cannabis include some cardiovascular side effects. A judge may have called it "safer than aspirin", but that's not actually saying much. See also [5]. Wnt (talk) 03:50, 15 December 2015 (UTC)

Don't forget paranoia. Now, if someone would just ask if donating blood has an immediate effect on blood pressure... 209.149.113.52 (talk) 19:43, 15 December 2015 (UTC)

Orangutan humor?

You may be familiar with that video of a young orangutan "laughing" when being shown a (pretty poor) "magic trick". I tried to find an analysis of what was going on a bit more serious (scientifically speaking) than what you usually get. All I could find was this. Have you seen anything by a bona fide ape specialist? It certainly didn't come up in my top Google results. Contact Basemetal here 12:05, 15 December 2015 (UTC) PS: I am aware that, unfortunately, Dan Zaleski (the American tourist who posted that video) showed the orangutan the trick "a few times" and then decided to post only "his best reaction" (rather than post the whole sequence) which might make it difficult for anyone to understand what's really going on: what if what we see was the tenth time he showed him the trick and the orangutan was laughing at him)? Contact Basemetal here 12:05, 15 December 2015 (UTC)

Wikipedia has a short article titled Laughter in animals and this article presents an overview of recent research in this area, with links to actual studies and other articles on the general question of humor in non-human animals. --Jayron32 12:39, 15 December 2015 (UTC)

Thank you for these useful links. Has anyone seen anything relating specifically to this case though? Contact Basemetal here 17:01, 15 December 2015 (UTC)

Sunrise and sunset

I read the articles (sunrise and sunset), but I am still not exactly clear. So I ask my question here. The news will report sunrise and sunset as an exact time. Let's say that sunset is reported as 5:00 PM as a hypothetical example. So, what exactly is different from 4:59 PM and 5:00 PM? What exactly has happened at 5:00 PM that did not occur at 4:59 PM? Thanks. 2602:252:D13:6D70:14DE:69F5:F4C:EAE3 (talk) 20:21, 15 December 2015 (UTC)

See Sunrise equation for the calculation of sunrise (and sunset). 209.149.113.52 (talk) 20:29, 15 December 2015 (UTC)

Unless you are looking out to sea, or on a perfectly flat plain, your local sunrise and sunset are unlikely to be at the published times for your area. In theory, what happens at a 5 p.m. sunset is that at 4:59 p.m. you can just see a tiny part of the top edge of the sun, but at 5:01 p.m. all of the sun is below the horizon. Sagittarian Milky Way explains below why even in an ideal situation, the exact minute is unlikely to be observed. Dbfirs 21:17, 15 December 2015 (UTC)

(edit conflict) At sunrise the first point of Sun circle would appear if the Earth was free of obstructions (like buildings, mountains, and waves) and the same elevation everywhere. I believe that height is mean sea level but I'm not sure if anyone ever does it with the location's height (which would make more sense for Denver for example). The result is slightly wrong if the air isn't whatever temperature and humidity they use or doesn't have the same air density to altitude graph (coldness and to a small extent lower water vapor % makes astronomical objects appear higher in the sky). The Sun generally rises and sets slower the higher latitude you are (it takes many, many hours to at the poles) and temperature inversions happen when it's cold enough so high latitude sunrise predictions can be very wrong. If they don't calculate this every year (because of leap days and stuff) or use good enough formulas (because near perfect formula is very long) then that introduces some error. At midlatitudes everything happens about 5 seconds earlier for each mile east of the newspaper's spot. They might calculate for sea level eye height and if they do then even if they calculate for your point of beach exactly and that spot's mean sea level and the sea is glass smooth and the Sun is setting over it and the sunset tide is mean sea level and everything else I wrote till now is perfect it'll still be around a quarter minute too soon at midlatitude just because you're standing and 6 feet tall instead of swimming. If you moved your eyeballs to 9 inches above the glass sea then the prediction would be 5 seconds too soon. If you're up to you're nostrils in water and your eye is 2 inches above sea level that 2 inches still makes the sun set 2.5 seconds later. If you hold your breath and put your pupils 1 inch above sea level (this is some calm sea!) then the sun sets about 1.667 seconds later because of that inch. (Reference: [6], the horizon is what hides the sun so that's the important part and 1 minute of arc is 4 seconds of right ascension but the sun sets in a slanting path at midlatitudes so add a little time for that)). Also, even if eyeball is in the place of prediction and everything else is perfect if it's only to the minute then it'll be at least 30 seconds wrong some days just for that, which is important if you're wondering about what's so special about 5:00 am. Make it 60 seconds wrong if they truncate. Sagittarian Milky Way (talk) 21:38, 15 December 2015 (UTC)

More important is that the published times for your area are actually times for a specific location in your area (e.g. the town hall). So you have to consider how far you are from the town hall. 89.240.30.128 (talk) 09:25, 16 December 2015 (UTC)

These days the times are recalculated every year but that wasn't always the case. During the Second World War Whitaker's Almanac started printing sunrise and sunset times for a variety of locations across the UK. After four years they just recycled the data for four years before. This continued for most of the second half of the twentieth century. When the almanac went over to computer typesetting they started using the accurate times provided by the Royal Greenwich Observatory. 89.240.30.22 (talk) 09:36, 16 December 2015 (UTC)

As Dbfirs is introducing some inaccuracies in his reply at "Length of Day" below, just to clarify:

• Dbfirs lives in the UK, so his responses purport to reflect the position as it is here.
• Leap seconds are not officially used in the UK. Published times are in GMT (or possibly BST in the summer, neither of which uses leap seconds).
• The only way that the general population will come into contact with leap seconds is if they listen to the "Greenwich Time Signal" broadcast periodically on BBC Radio 4.
• Very few people listen to the BBC, and even fewer listen to BBC Radio 4. 89.240.30.73 (talk) 09:59, 16 December 2015 (UTC)

I don't know about your other points (though "Leap seconds are not officially used in the UK" seems implausible), but "Very few people listen to the BBC, and even fewer listen to BBC Radio 4" is simply untrue. From 2013 data: "we saw a record 11m tuning in to the station each week". More recently, the report linked from here for April-June 2015 shows "average weekly reach" for BBC radio as 35m, with 10.6m for Radio 4. (And that doesn't include the World Service, with an estimated audience of 210m.)

December 16

list of stars about 30000 ly distant please

Hi - it's for a novel - I need some sunlike stars that are about 30,000 lightyears away - ones with curious names/designations especially welcome. Thanks in advance Adambrowne666 (talk) 00:37, 16 December 2015 (UTC)

The thing is that modern astronomers don't generally give stars cute names - they're generally just numbered in some manner. Named stars tend to be the ones that have been known for a very long time - typically they are naked-eye objects. 30,000 ly is about a third the way across the galaxy - and stars that are that far away aren't usually visible without a telescope. There are also an immense number of stars out at 30,000 ly - at least 100 billion of them. Now, clearly we're not going to name any of them unless they are REALLY special - like maybe super bright. Why would be bother to name a boringly typical sun-like star out of the billions out there?

So the answer is "None" - there are no named stars out at those distances - and certainly no sun-like stars with names at anything like that distance. SteveBaker (talk) 00:56, 16 December 2015 (UTC)

Thanks, Steve - names would have been a bonus, but any sort of designation would do. Adambrowne666 (talk) 01:00, 16 December 2015 (UTC)

For example, if you take the text dump of the Guide Star catalogs, a set of "all-sky optical catalog(s) of positions and magnitudes of approximately 19 million stars and other objects" that are specifically used by scientists to aim the Hubble Space Telescope, you'll see things like:

N003-AAJE  46.13902  84.36855  0  99.999  99.999  3  16.759  16.685  3  16.082  16.086 
N003-AAAF  45.84270  84.48269  0  99.999  99.999  3  14.565  15.112  3  14.730  14.753
N003-AABF  45.75025  84.36574  0  99.999  99.999  1  16.999  17.003  1  16.262  16.315

...and so on, for 19 million entries. The "name" of one of these stars is, for example, "N003-AAJE."

Unless that specific entry is scientifically interesting for any other purpose besides its relative location, chances are very high that no scientist has ever bothered to study that star to determine its distance, or its spectral type, or anything else about it. A tiny fraction of the entries in these catalogs have been subjected to intensive scrutiny, but most of them are known only as dots with positions and approximate brightnesses.

What's more: if you use a different coordinate system, or even if you just a different sky catalog - that dot might be listed by a totally different designation. It might not even be listed in a different catalog.

Nimur (talk) 01:15, 16 December 2015 (UTC)

Only the first field seems like a designation. The next two seem like declination and right ascension in degrees in some order and the last four seem like magnitudes in some order (probably B, V, R, and I)? Sagittarian Milky Way (talk) 01:19, 16 December 2015 (UTC)

And the Guide Star Catalog II has 1 billion stars instead of 19 million (down to magnitude 21) and per absolute magnitude and interstellar extinction the average sunlike star that distance might be too dim to appear even there. Space is Big! If it did appear it would probably be unusually far from the galactic plane for a Sun-like star as the Sun is fairly metallic by star standards. Sagittarian Milky Way (talk) 01:27, 16 December 2015 (UTC)

To be honest, I'm not sure exactly how to interpret every column in the database. The text file I pulled those data from did not include a labeled header; and the database in this particular text-format does not seem to match the documentation in the published literature linked from the main website. This text-dump is evidently intended for consumption by a very specific computer program - it's really not aimed at human readers.

If you're very interested, you can read about this specific catalog at the The Guide Star Photometric Catalog I, from the Space Telescope Science Institute.

Anyway, for our OP: if you are writing a hyper-unrealistic Space Trek fictional story, you can just give your star a great name that will enthuse your readers (like Proxima Nimur VII) ; but if you're writing hyper-realistic fiction, you need to re-think the way you portray designated objects space. Space is really big.

Nimur (talk) 01:29, 16 December 2015 (UTC)

Of course, if this is happening in the future we might be able to tell if it's interesting enough to name (if it has one of the most Earth-like planets known, for instance). That might be done with a telescope in space many miles wide with a spectroscope, or suspended animation and fast automatic spaceships that can function for ages so you could go there where it takes much less equipment to find out how Earth-like it is. Your list might be available to Earthlings before a few decades from now but you could give it an even more robot-sounding catalog number from a bigger alien or future human catalog if it seems likely that the characters would be using it. Sagittarian Milky Way (talk) 01:54, 16 December 2015 (UTC)

Or a smaller alien catalog from a planet much closer to the star than we are. Sagittarian Milky Way (talk) 01:58, 16 December 2015 (UTC)

Why 30,000 light years by the way? Any particular reason or cause it sounds good? Sagittarian Milky Way (talk) 02:02, 16 December 2015 (UTC)

Thanks, everyone. It's 30000 ly so that the protagonists on a world circling one of those billion unnamed stars can imagine looking back at Earth with a putatively perfect telescope and see something (in their imagination) happening 30000 years ago.Adambrowne666 (talk)

@Adambrowne666: You can check List of most luminous known stars - some are around 30,000 ly away. One that stands out is the Pistol Star -- if you're writing a culture of gunslingers influenced by American cowboy movies, I think you're in luck! :) Wnt (talk) 14:00, 16 December 2015 (UTC)

Length of year versus length of day

It is somewhat of a "fiction" that the year is 365 days long. Actually, it is something like 365.25 days long (or so). And that is why we have the need for a leap year every four years. So, what about the length of the day? Is it exactly 24 hours? Or is that also a "fiction"? It seems a little too convenient to be 100% accurate, no? 2602:252:D13:6D70:14DE:69F5:F4C:EAE3 (talk) 02:28, 16 December 2015 (UTC)

Depends on what you mean by a "day". There's a Civil day, solar day, a sidereal day, etc. The civil day is defined as exactly 24 hours, and the sidereal day is defined a 1/365.24 of the year. The solar day varies slightly depending on the specific day of the year. All three days are within a few minutes of each other. --Jayron32 02:51, 16 December 2015 (UTC)

To be more specific, the Julian calendar set 365 days with a leap day every four years, making 365.25 days. In the year 1582, Pope Gregory made an adjustment to correct an error that had accumulated to about 10 days. In that year, and for that year only, October 4th was followed by October 15th, thus advancing the date by 10 days. The intervening days (5th -14th) simply do not exist. There was also specified that 3 of every 4 centesimal years (ending in 00) would be common years, not leap years. Thus 1600 and 2000 were leap years but 1700, 1800, and 1900 were not. This is where the 365.24 length comes from, and it is this Gregorian calendar that we live under today. Most of Europe adopted the Gregorian calendar immediately in 1582. Great Britain and its colonies (including what is now the US) did not until 1752, by which time another day's error had occurred, so September 2 1752 was followed by September 14, an advancement of 11 days. Akld guy (talk) 03:17, 16 December 2015 (UTC)

Hmmm. OK, now my head is spinning. I thought that a year was how long it takes the Earth to revolve around the sun. So, if the Earth starts at one point (Point A), makes a full revolution around the sun, and ends up at the same starting point (Point A again), that whole trip will take 365.25 days. I thought that a day was somehow similar. Something like how long it takes the Earth to rotate on its axis for one full spin (or something like that). And that was calculated to be 24 hours, which is where we get our "calendar day" from (e.g., the day we call December 15 versus the day we call December 16, etc.). Am I on the right track? In other words, our calendar "day" is derived by some celestial happenings (with the Earth or sun or moon or whatever). So is that celestial event exactly 24 hours? Or is it "off" by a bit, but we just use the "fiction" of 24 hours, for convenience? (Like, for example, in actuality it is really 24 hours and 3 minutes and 18 seconds, or whatever.) Thanks. 2602:252:D13:6D70:14DE:69F5:F4C:EAE3 (talk) 05:58, 16 December 2015 (UTC)

In basic terms, yes: a year is how long the earth takes to go round the sun, and a day is how long the earth takes to spin. The problems that make things a bit more complicated are:

1) How do you actually tell when the earth has got back to its starting position? There is more than one way of doing this (depending on what you use as a reference point), which give slightly different answers. Hence we have concepts like the stellar day and sidereal day

2) The earth/sun system isn't like a machine that does exactly the same thing all the time. Its a slightly wonky lump of rock being pulled round a big ball of plasma by gravity, while other lumps of rock and gas tug at them with their own gravity. This means things wobble a bit, and don't always move exactly the say way or at the same speed. Which means the time take to go round the sun or rotate on its axis can change slightly. This in turn means that - for people who need to define time really precisely, they need to use a consistent definition of year, day, second etc that aren't dependent on what the earth is doing right this moment. Iapetus (talk) 13:14, 16 December 2015 (UTC)

The day is currently 24 hours and 1 millisecond. It was 24 hours when the second was first defined to be something other than 1/86400th of a non-fictional day (the late corset era). We are now 1 minute and 8 seconds behind then as a result of the rotation slowing down until a day is 24 old hours and 1 millisecond. We can't change the second, it would screw up precise scientific work so we have to add leap seconds every so often. It takes 365.256 days for the Earth to revolve once but the axis isn't lined up as it wobbles very slowly (26,000 years per wobble) so the seasons (which is what we care about most) take under 365.2422 days to repeat (but well over 365.2421). Those are 365.2422 real days, not the 24 hour ones that're fictional now. Sagittarian Milky Way (talk) 06:15, 16 December 2015 (UTC)

The Earth actually takes 23 hours and 56 minutes and 4.091 seconds to rotate but by the time it revolves once it has "canceled" one rotation by the revolving so it needs to make up one rotation every year. This is why it's 24:00:00.00 on average between noons or midnights — it needs to make up 1 day's worth of rotating per year so it takes 24 hours. Sagittarian Milky Way (talk) 06:24, 16 December 2015 (UTC)

The "celestial day" you refer to is what is called the sidereal day, this is the length of time it takes for the earth to spin 360 degrees around it's own axis. This is equal to 23h56m. The "solar day", which is how human beings historically defined the day, is the length of time it takes the sun to reach the same position in the sky from one day to the next. Historically, this is how we defined the "day" that we cut up into 24 hours, so the solar day is exactly 24 hours long by definition (some complication: it varies because the earth's rotation and its orbit around the sun are not perfectly even, circular, or fixed). Why is the solar day slightly longer than the sidereal day? Because in the time it took the earth to rotate once around its own axis, it has orbited slightly along its path around the sun. Which means it needs to rotate slightly further for the sun to again be at the same point in the sky since yesterday. The earth's orbit around the sun has essentially caused the sun's position in the sky to "un-orbit" the earth by 4 minutes, so it is 4 minutes behind where it needs to be since yesterday. Thought experiment: if you play this through for an entire year, can you see that the earth's 1 orbit around the sun means that the sun has fully "un-orbited" the earth by 1 whole day over the course of the year? This means that for the 365.24 days we measure by the solar day, the earth has actually rotated exactly 366.24 times on its own axis. If you take 24h*365.24/366.24, you get the 23h56m number. I hope this helped and didn't confuse you further! Zunaid 06:19, 16 December 2015 (UTC)

Yes, the "real rotation" and "real revolution" is 23:56:04 and 365.256 days, but the "real day" and "real year" are 24:00:00.001 and 365.2422 day. The fake day and fake year are 24 hours and 365 days respectively. Sagittarian Milky Way (talk) 06:30, 16 December 2015 (UTC)

There are other types of days and years but those would just be good for confusing you. They're very specialised and trivia-like, like the human-powered underwater speed record. Sagittarian Milky Way (talk) 06:38, 16 December 2015 (UTC)

Thanks. So, the "real day" is not 24 hours, but is 23:56 (or, in other words, 4 minutes short of a full 24 hours). So don't all of those "four-minute deficiencies" build up and accumulate over time? So, after 2 days, we have an 8-minute deficiency. After 7 days (one week), we have a 28-minute deficiency. After 30 days (one month), we have a 60-minute deficiency. And so forth. And doesn't that accumulated "error" make the days/times get out of sync? Which is why we add that extra leap year, I think? So that the "accumulation" of that "extra" 0.25 of a day beyond the flat 365 days per year does not accumulate too much and throw the "year" off cycle. If we did not have a leap day, then every four years, we have an extra "day" accumulated that never gets accounted for. The way that we "account for" that extra accumulation is by adding a leap day. So, wouldn't it be the same idea for the 4-minute deficiency gap for the "day"? Thanks. 2602:252:D13:6D70:14DE:69F5:F4C:EAE3 (talk) 07:47, 16 December 2015 (UTC)

No, you have misunderstood. The 4 minutes per day add up to one full revolution per year, which is accounted for by the revolution of the earth round the sun. A day is the average time taken from one noon to the next (see Equation of time for why this isn't constant), and the only correction necessary is the occasional leap-second. The leap year is to keep the seasons from drifting from their usual dates (see Gregorian Calendar). Dbfirs 08:14, 16 December 2015 (UTC)

Some of Dbfirs' disingenuities have been corrected in "Sunrise and sunset" above. A day is the average time taken from one noon to the next as he says but this average is the "mean solar day" and no further correction is required for "leap seconds". Joe Public (i.e. the person to whom this resource is directed) does not use leap seconds. The only people who use leap seconds are scientists who need units of measurement which are not constantly changing in length, and have therefore devised an artificial "SI second" which is the length of the mean solar second as it was back in 1820. 89.240.30.73 (talk) 10:17, 16 December 2015 (UTC)

The sidereal day is aligned with the stars. So if Taurus rises at a certain time within one sidereal day, it will rise at a certain time on any sidereal day. Problem is, the Sun might be in Cancer, Libra or Capricorn, so while you might know what time of sidereal day it is, you don't know if it's light or dark out! So people don't like the 23h56min day very much, even though it's always the same length.

The easy thing to do is to make up for how much the sun moves, but here's the trick... it doesn't move at the same rate all the time! Well, technically, it doesn't move much at all, relative to the barycenter of the solar system or whatever, but that's another story - what I mean is, the Earth's orbit is a tad elliptical and so sometimes the planet is whipping around the perihelion a little faster, sometimes further out and a little slower, so the Sun makes a whole analemma thing that can really confuse the hell out of you even if you actually understand everything I've written so far. But using the same average correction is the sanest way to do things so that your computer video plays back at the same rate regardless of what season it is. Wnt (talk) 14:09, 16 December 2015 (UTC)

Will global warming slow down or speed up the earth's rotation speed?

Some news outlets (for example [7], [8], [9]) affirm that global warming will speed up the earth's rotational speed while others (for example [10], [11], [12])affirm that it will slow it down. They can't very well both be right. Contact Basemetal here 03:51, 16 December 2015 (UTC)

First let's kill the echoes. The first two that say faster cite Felix Landerer at Max Planck Institute ( http://onlinelibrary.wiley.com/doi/10.1029/2006GL029106/full ) as of 2007; the latter four that say slower link to http://advances.sciencemag.org/content/1/11/e1500679 more recently. My assumption is the argument for slower is that glaciers are near the poles and when they melt the water has to go somewhere further out; the argument for faster is that the ocean overall expands, and water presently in deep basins ends up washing into the shallower Arctic Sea, North Atlantic etc. Both studies are what they are and we'd be hard pressed to settle the issue amongst ourselves. Wnt (talk) 04:45, 16 December 2015 (UTC)

They can't both be right, but they could both be wrong. Reminds me of National Lampoon's newspaper satire, in which articles on consecutive pages had different scientists claiming that we were on the virge of global boiling and global freezing. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:30, 16 December 2015 (UTC)

Global boiling: Only 1 billion more years. Global freezing: a few billion after that. Sagittarian Milky Way (talk) 05:35, 16 December 2015 (UTC)

Actually they can both be right. When melted, water becomes much more dense, but then it becomes less dense. Once the Antarctic ice is all melted, bringing rotation to its slowest rate, the oceans will continue to expand and thus redistribute themselves, speeding it up again. Whether it takes a a billion years or a hundred, I'd guess global boiling should reverse the sign of things a third time by moving the water far up into the atmosphere. Wnt (talk) 09:55, 16 December 2015 (UTC)

They might both be right at future points in time, but not at the same point in time. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:57, 16 December 2015 (UTC)

At the same time it can be true both that it "will speed up" and "will slow down". Wnt (talk) 13:54, 16 December 2015 (UTC)

Expands should correlate with slower. The mass doesn't change. When an ice skater puts her arms out she spins slower, when she brings them in by her side she spins faster. However looking at the arguments I think I agree the redistribution of the water would make a bigger difference than the ice melting so my opinion is on the faster side. I think it should just about be possible to measure the changes so far and figure out who is probably right. Dmcq (talk) 12:49, 16 December 2015 (UTC)

Why would redistribution of ice have any noticeable affect? It isn't like the ice on the surface amounts to much. Mt. Everest, the largest feature jutting out of the surface above sea level, sticks out 0.1% of the mean radius of the Earth. That is negligible. I feel that many people (even those who are very educated) picture the surface of the Earth as a very thick layer. It is more like the peel of an apple. If you add a few crystals of ice to the outside of an apple, the spin speed won't change significantly. Similarly, if you redistribute a very very thin layer on the outside of the Earth, it won't mean much as far as spin goes. 209.149.113.52 (talk) 13:42, 16 December 2015 (UTC)

The effect is, of course, exceedingly small; however, the length of day is something that can be measured with exceedingly high precision. It is not uncommon for people to write about the effect of an earthquake on the length of a day, and this is more than that. Because measurements really can be taken, it is also a way to probe or at least verify models of the distribution of the oceans, etc. It is only important in an academic sense. Wnt (talk) 13:54, 16 December 2015 (UTC)

• <rant>This is the problem with popular reporting of science. It is particularly egregious with health and medical reporting (especially nutrition) but it clearly evident above. When science reports "cause X produces effect Y", the media reports this as "ONLY cause X produces effect Y, and there are no other causes or effects, and here's everything you need to know, and nothing else matters!!!". So you get reports like this complete and utter bullshit titled "A Glass Of Red Wine Is The Equivalent To An Hour At The Gym, Says New Study" No, it fucking doesn't, so stop that. The study showed that one ingredient in red wine, reservatrol, had certain physiological effects on a few body systems that mimic strenuous exercise. What the study does NOT SAY is "There is no difference in your body between drinking red wine and physical exercise, so just drink red wine and it's all the same thing". The science never said that, but the popular press comes out and basically says exactly that. Because journalists (as a subset of the entire population) have no idea how experimental science works. A properly constructed experiment " typically include controls, which are designed to minimize the effects of variables other than the single independent variable." to quote the Wikipedia article. That means, that when scientists publish a study, the study is almost always focusing on a single independent variable and carefully controlled to reduce, minimize, or control all other variables. So when scientists run an experiment as they did in the above studies regarding climate change and the speed of the earth, what they do is cafefully control for one aspect of climate change; or in these cases one aspect of warming oceans, and then see what the effect of that one single variable is on one single effect. In this case, the rotation of the earth. It turns out that depending on how you define your single variable, you can produce speeding and slowing effects. So which is actually happening? The answer is: both speeding and slowing, because both of those variables come into play, as well as probably dozens or hundreds of other variables that we didn't test for in these experiments" So, when you ask science a vague question like "Will the earth speed up or slow down because of climate change" the honest answer is either "It will do X so long as nothing else happens as well" or "We can't predict exactly because there are lots of factors at play, but we do know that this cause would lead to it speeding up because of XYZ, or this other cause could lead to it slowing down because of ABC." The sort of "tell us the future perfectly so we can stop worrying!" expectation of science is a complete misunderstanding of how knowledge grows...</rant> --Jayron32 13:43, 16 December 2015 (UTC)

Journal Articles

How to find journal articles for free about agriculture? Googled, but still hard to find. Any specific sites'd be much helpful... Thanks!

Learnerktm 10:14, 16 December 2015 (UTC)

Have you tried https://scholar.google.com/ ? It's not part of the regular google search, and google no longer advertises the service on their main page (they used to), so it is hard to find, but Google Scholar is where I go to search academic journals. --Jayron32 12:52, 16 December 2015 (UTC)

Energy expended per newton per second

Hello. Considering that human muscles are very inefficient, how many joules does an average human being have to actually expend to exert a force of 1 N for a duration of 1 second? Thanks.Leptictidium (mt) 14:01, 16 December 2015 (UTC)

Read the Wikipedia article Muscle#Efficiency, which has all the necessary figures to help you answer the question, and probably answers it directly anyways. --Jayron32 14:07, 16 December 2015 (UTC)

What sense is my betta fish using to detect the arrival of food?

I put this on the science desk because I guess it's a biological question. My bowl is basically a large sphere about 10" in diameter and when the fish, which is about 2" in length is anywhere, even down at the bottom, when I drop its food, which is 3-4 pellets of betta fish food, each pellet being maybe 1mm in diameter, within about a second, the fish comes up to where the pellets are. Is it likely by smell, i.e., some molecules from the pellets propagating through the water, by sight (there's a fake plastic plant in the middle of the bowl that doesn't seem to slow it down), or by feeling that something has been dropped on the surface? 131.131.64.210 (talk) 14:08, 16 December 2015 (UTC)

I don't know directly (and it may vary between different species of fish), but I will direct you to reading the article lateral line. The first sentence of that article "The lateral line is a system of sense organs found in aquatic vertebrates, mainly fish, used to detect movement and vibration in the surrounding water." So, IF the fish is using the vibrations caused by the food hitting the water to know it is being fed, it would be the lateral line that is doing that. It could also be a combination of several senses, because you do this too i.e. you know dinner is coming BOTH because you saw your mom go into the kitchen, and you heard her rummaging in the cabinets for pots and pans, and you smelled the dinner cooking. It wasn't just one, but all of these senses that led to your conclusion. It could be the same for the fish. But the lateral line article is an interesting read, not the least of which is because it's a sense system unlike anything humans have. --Jayron32 14:12, 16 December 2015 (UTC)