Wikipedia:Reference desk/Archives/Science/2010 January 14

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January 14

Could you explain why all parrots seem to be able to communicate with each other?

With parrots, you can pretty much put any combination of species together in the same place, provided that they get on with each other as individuals and see that they're able to communicate and interact with each other pretty well. Even if they're species from different parts of the world. Put a macaw next to an African grey for example and they'll sit next to each other like friendly parrots do, preen each other, share food, etc. and understand each others body language perfectly well. Or a cockatoo and an amazon parrot, or a budgie and a lovebird. Sometimes they'll even pair up and try to breed with each other.

Why is it that (nearly?) all parrots have the capability to understand and be understood by all other parrots? —Preceding unsigned comment added by 95.148.104.164 (talk) 01:04, 14 January 2010 (UTC)

See the article Bird vocalization. Cuddlyable3 (talk) 23:24, 14 January 2010 (UTC)

Thanks for your reply but that doesn't really answer my question. I was talking more about behaviour and body language than vocalizations. --95.148.108.215 (talk) 01:16, 15 January 2010 (UTC)

The OP seems to feel that the ability to size each other up and interact when thrown into a cage with a stranger is a special property of parrots. I suggest that the same would be true of any two dogs from any part of the world, any two cats, any two people, or any two other animals of the same species. They would fight a bit, or mate, or groom each other, or share food,or fight over food, or some sequence of the above. Edison (talk) 17:44, 15 January 2010 (UTC)

Especially if they share the same CAGE. GabrielVelasquez (talk) 21:10, 2 October 2010 (UTC)

But a Macaw and an African Grey are different species! Any two dogs or any two housecats are going to be different members of the same species. What would happen if you put a dog together with some other canid? A fox perhaps? APL (talk) 19:24, 15 January 2010 (UTC)

I think that this and this are examples of what the OP was asking about. Parrots of different species hanging out and doing the typical social parrot thing. --Kurt Shaped Box (talk) 15:12, 16 January 2010 (UTC)

Would a spaceship travelling through a nebula leave vortices behind?

I posted this, initially, in the Fluid Dynamics discussion page and was referred here (after they took the time to give a partial answer anyway, which I thought was pretty nice of them):

Sorry if this is a bit lame, but this question has bothered me for a while, and I don't have the skill to answer it myself.

In the opening credits of Star Trek Voyager (I know, but try to keep reading anyway), there is a scene that shows the ship passing through, presumably, a nebula. YouTube has the opening credits if you want to look.

Anyway, the ship causes some nice vortices, very similar to the Rayleigh–Taylor image in the article.

My question: would it really?

A nebula is, well, nebulous. Is it considered a fluid? I visualize it as sparse particles in a vacuum. At what point are there enough particle available that they interact and form those swirls. I think that you'd really see a perfect wake - a 'V' or cone spreading from the ship.

Where is the line between "dust particle scattered about in a near-vacuum" and "fluid"?

75.152.185.94 (talk) 01:54, 14 January 2010 (UTC)

Well, there would be gas as well as dust - and gasses are "fluids". However, through most of a typical nebula, the density of all of that stuff is spectacularly sparse. A nebula is hardly distinguishable from a hard vacuum. We really only see them because we're looking through so many lightyears of material. At those kinds of densities, the spaceship maybe pushes a few hundred atoms out of the way each second...technically, I suppose that's a swirl...but I doubt that many people would really classify them that way.

Having said that - there are places in nebulae where new stars are forming. In those places, gravity is bunching the material together - and the density goes up spectacularly. By the time the gas gets dense enough to ignite into a star, it has a density higher than iron. So somewhere between the center of a newly forming star and the near-vacuum of the rest of the nebula - there would have to be relatively small regions with a density similar to normal air pressure here on earth - or close to the density of liquid water. In those regions, our hypothetical spaceship would certainly leave a nice turbulent wake...but that would be a tiny, TINY percentage of the overall volume of the nebula - and they would be short-lived because once that amount of material gets together at that density, the gravity that's compressing it would be around 1g so it'll be falling inwards very fast indeed and very soon the star will ignite and our spaceship had better not be anywhere nearby!

SteveBaker (talk) 02:44, 14 January 2010 (UTC)

It must have taken Cpt Janeway forever to find a nebula with exactly the parameters Steve just described.

I suppose it might be meant as flying upwards out of a gas giant. (The next couple shots show Voyager flying near one of similar color) But I don't imagine that it would be easy to find one made of such a brightly colored atmosphere that you could just fly through for a photo op.

What makes the shot really unrealistic is the impressive way Voyager "punches" out of the nebula/planet. For some reason there's a reasonably well defined demarcation between "visible blue fluid" and "nothing". (I think in real life you'd need fluid in the "clear" sections anyway, to get those sorts of fluid movements.) APL (talk) 03:09, 14 January 2010 (UTC)

The relevant factors are the density of the nebula and the speed of the spacecraft. If I'm interpreting this correctly, the centre of the Orion nebula (as good a nebula as any) has a density of about 3000 particles per cubic centimetre. That compares with about 3x10¹⁹ in air. You can get decent vortices at about 10 m/s in air, I'd guess, so it stands to reason that one would need to travel at about 10¹⁷ m/s to get them in a nebula. That is about 300 million times the speed of light (and the ship clearly isn't at warp)... As Mythbusters would say: BUSTED! --Tango (talk) 03:31, 14 January 2010 (UTC)

I don't think that's right. You need to know effective viscosity, which does not scale between gas and plasma. --Dr Dima (talk) 03:37, 14 January 2010 (UTC)

Sure, there is a contribution from different viscosities, as there is from all kinds of other factors, but are they likely to account for more than 8 orders of magnitude? --Tango (talk) 03:43, 14 January 2010 (UTC)

Effective viscosity may vary by far more than 8 orders of magnitude under different conditions. More importantly, you just can not compare a hand moving in air with a starship moving in dusty plasma by simply scaling density and velocity. You need to at least evaluate the Reynolds numbers in both cases (that is, compare densities, velocities, sizes, and viscosities). And that only applies for unmagnetized plasma. However, plasma is likely to be magnetized, so things are far more complicated than that. --Dr Dima (talk) 04:01, 14 January 2010 (UTC)

Your question is very complicated indeed. That is because we don't really know what exactly the conditions are in any particular nebula. Very low density does not imply lack of interaction; indeed, most particles in the nebula are probably charged (whether those are individual electrons, ions, atom/ion clusters, or dust grains) and therefore interact via long-range electromagnetic interactions, limited only by Debye screening radius which for a hot low-density plasma may be very large. And then there is also a magnetic field, which probably is carried along with the plasma flow. It is hard to predict how a macroscopic object would perturb such a medium. --Dr Dima (talk) 03:28, 14 January 2010 (UTC)

On a related subject, it has been hypothesized that Earth produces vortices as it passes through solar wind (there may occur a Kelvin-Helmholtz instability at the boundary between the Earth magnetosphere and the solar wind), but I do not know if this was experimentally confirmed. Starship may or may not possess a magnetosphere -- I forgot to ask Scotty how the shields work :) -- but if it does, it may produce a wake by this mechanism. --Dr Dima (talk) 03:45, 14 January 2010 (UTC)

You might be interested in The Physics of Star Trek. Excellent question, by the way.--Shantavira|^{feed me} 08:25, 14 January 2010 (UTC)

Bow shocks are observed from stars moving through nebulae, but of course that's a much larger scale than Voyager, and not quite the same as vortices. -- Coneslayer (talk) 12:02, 14 January 2010 (UTC)

I don't think the vortexes themselves are the crux of the unbelievability. Federation star ships seem to require a plethora of fields and beams unknown to modern (ie:real) science. So if you could find a place where Voyager might conceivably fly through such a wonderfully visible cloud of blue stuff, you could claim that any irregularities in the way it moved were caused by the (for example) navigational deflector or (for example) the bussard ramscoops. APL (talk) 18:00, 14 January 2010 (UTC)

Thanks for the great answers! I turned this into a blog entry yesterday, and updated it with these replies today:

Where No One Has Cared Before

(Feel free to bork that link if shameless self-promotion is not kosher)

75.152.185.94 (talk) 01:24, 15 January 2010 (UTC)

One thing - our contributions here (and all other Wikipedia content) are licensed under the CC-BY-SA 3.0 license and the GFDL. When you cross-post our replies onto someplace like that blog, you make sure that the site you are posting it to is prepared to publish it on compatible terms. Sadly, sartastic.com claims "all rights" for it's content - which is most definitely NOT compatible. I'm somewhat sure that everyone here is actually OK with it - but you can't assume that when you copy our words elsewhere. SteveBaker (talk) 02:41, 15 January 2010 (UTC)

No sweat, SteveBaker. I'll make that article CC-BY-SA. (I own the site, so can do so) 75.152.185.94 (talk) 02:57, 15 January 2010 (UTC)

I added "This blog entry is released under the following licenses: The Creative Commons BY-SA 3.0 license, and the GNU Free Documentation License." to that section (with hyperlinks). Does that work? 75.152.185.94 (talk) 03:25, 15 January 2010 (UTC)

Yeah - that should be fine. It's really not a big deal - but you never know when someone is going to go all anal about it. SteveBaker (talk) 19:57, 15 January 2010 (UTC)

Which combination of neutron flux and gamma rays decontaminates nuclear waste best?

I was intrigued by the discussion here, so I looked at the source cited at the top, and wonder: What is the optimal combination of neutron flux and electromagnetic radiation to transmute radioactive waste from nuclear reactors into the safest set of isotopes? 99.38.148.255 (talk) 06:07, 14 January 2010 (UTC)

Assessed earthquake risks

Hi. After the 2008 Sichuan earthquake, I found out that there had been a significant risk published for a strong earthquake in the region by 2003, and after the 2010 Haiti earthquake there was information regarding the potential for a quake in the area since 2008. This leaves me wondering, what other earthquake risks have been determined around the world, where a distinct possibility exists within say the next decade? Are there any complete lists for these risks that are accessible through the Internet? Thanks. ~AH1^(TCU) 13:02, 14 January 2010 (UTC)

For US locations there is http://geohazards.usgs.gov/eqprob/2009/ which is fun and scary. Dragons flight (talk) 13:12, 14 January 2010 (UTC)

Damn, Dragons was quick. This maybe? Earthquake Hazards Program. More generally anywhere on the Ring of Fire, that hasn't had an earthquake 'recently'. Tokyo is supposed to be way overdue for a quake. --220.101.28.25 (talk) 13:21, 14 January 2010 (UTC)

Earthquake prediction may also be of interest. --220.101.28.25 (talk) 14:04, 14 January 2010 (UTC)

It's easy to say which areas of the world are at risk, generally speaking, over a long-enough time horizon. The problem is that there's no good way to know how small that horizon will be—it could be the next year, it could be decades from now. It could be The Big One, or it could be a lot of smaller ones. There is not a lot of consensus on what to do about low-probability, high-damage catastrophes. People don't like paying for them ahead of time, because if they don't actually happen it feels like a waste. If nothing is done, though, then it looks like neglect—but it might be a problem for "the next guy" and not you. People don't like being told they can't or shouldn't live somewhere because there are long term geologic risks associated with the place, and arguably we tend to overemphasize these kinds of "acts of god" risks more than the more mundane ones that actually kill most people (in Los Angeles, far more people die from automobile accidents than they do from earthquakes, yet everybody complains about the quakes as the "scary" thing). --Mr.98 (talk) 14:46, 14 January 2010 (UTC)

Thanks for the links, but what I'm looking for are published risk analyses for regions around the world, not just the US, and not current earthquakes either. Is there a list, or perhaps a map, of such assessments? Is there a way to search for this by country? ~AH1^(TCU) 03:45, 16 January 2010 (UTC)

true surface area

Normally surface area of a region is calculated as the area within a circcumferance. Is the an article which instead provides the surface area which includes the up and down surface of mountains and valleys as well such that for instance one might have a more accurate knowledge of true surface area? 171.100.15.157 (talk) 14:23, 14 January 2010 (UTC)

Usually this question is taken to not have a good answer. See coastline paradox for the "true length" version of the question; similar things happen when you try to consider every cave and knoll and every pebble in each cave and on each knoll. --Tardis (talk) 15:21, 14 January 2010 (UTC)

Paradox or not this seems to be the only explanation how China can produce the most watermelon, apples and other crops in the world. Is there at least an approximation that is based on the length of the shortest straight line used to perform the measurement? For instance, the shortest straight line being 1//2 mile would result in a longer cost line than one with a base minimum straight measurement of 1 mile. 171.100.14.125 (talk) 15:45, 14 January 2010 (UTC)

Mountains and valleys won't make a big difference to the surface area of a country. A grade of 30% (3 in 10) is quite steep, but an overall slope of 3 in 10 (16.7 degrees) across a whole region changes its surface area by less than 5%. The People's Republic of China is a big country - third or fourth largest in the world, depending on whose figures you use (see List of countries and outlying territories by total area) - and has the second largest irrigated land area in the world, after India (see List of countries by irrigated land area). Our article Economy of the People's Republic of China says "Yields are high because of intensive cultivation, for example, China's cropland area is only 75% of the U.S. total, but China still produces about 30% more crops and livestock than the United States". So it is entirely plausible that it is a leading producer of the crops that you mention. Gandalf61 (talk) 16:06, 14 January 2010 (UTC)

Plants need sunlight to grow. The sun doesn't shine extra light on mountains to compensate for their extra area. — DanielLC 17:13, 14 January 2010 (UTC)

Although the fractal/coastline-paradox answer seems like a useless, perhaps over-pedantic answer - it is none-the-less completely true. You absolutely cannot get a meaningful answer to this question. In a very real sense, any number whatever between the 2D 'plan-view' area and infinity are equally valid. Sure, you can define a fixed length 'measuring stick' (1 meter, say) and come up with an exact answer at 1 meter resolution - but that doesn't tell you anything whatever of value unless you're doing something like paving an area with 1 meter paving slabs. Even though it seems that 30% is a 'typical' slope - there will be undulations within any real 30% slope that will result in some 50% regions into which you can sneak a few extra watermelons. So we should not give you a concrete answer because whatever it is, it's WRONG. We see this all the time with the coastline paradox - the actual lengths reported by various agencies for the length of coastlines of particular countries really do disagree by massive amounts. Why on earth any of them try to report this is beyond me! SteveBaker (talk) 17:41, 14 January 2010 (UTC)

This is especially true because mountains are much closer to true fractals than coastlines. Measuring a coastline with a resolution greater than a meter mostly meaningless, but a mountain could literally be measured at a very small scale and give meaningful results.

(Not that a watermelon would care if some divots in the ground doubled the theoretical ground area.) APL (talk) 17:55, 14 January 2010 (UTC)

It may seem pedantic, but strictly speaking infinity is not an option. Since matter is composed of discrete atoms, eventually one reaches a point where the shape can no longer be fractal and there is no possibility to cram in any more structure. Any mathematically rigorous definition of area that is consistent with normal preconceptions of what area should mean, must be bounded simply because the number of atoms is bounded. In practice, that bound may not even be very large for objects that happen to be macroscopically smooth. Dragons flight (talk) 19:13, 14 January 2010 (UTC)

Yeah, great, we all know about fractals, 10 out of 10, let's give ourselves a big pat on the back for being so clever - but the OP's real question is do mountains and valleys in the real world create a significant difference between the actual surface area and the plan area of a region at a scale of measurement consistent with growing watermelons, and the answer to that question is quite definitely NO. Gandalf61 (talk) 23:44, 14 January 2010 (UTC)

Since we are considering crop production, fractal landscape is indeed, as it was presented, a facetious and pedantic answer. We live in the real world where we need to make the right approximations. The first one I will make is that plants mostly grow vertically and so sloping land is of no effective advantage to crop production. Especially since to farm steeply sloping land it is often terraced. —Preceding unsigned comment added by 129.67.39.49 (talk) 14:17, 15 January 2010 (UTC)

"True" area is misleading. It is a fuzzy "conceptual definition." If I buy a 1 acre farm on a hillside, and neglect it so that deep ruts from erosion appear, it would seem silly to brag that I have increased my area because it now has deep crevices all over it. It makes more sense to refer to Operational definitions. The area is defined by the process used to measure it, not by some abstract "true area as God sees it." Land area is measured with a leveled surveying tape or the modern GPS equivalent. This has been true for at least a couple of hundred years. An operational definition of a coastline or the slant area of a mountainside or cliff might be defined via a specified spline mathematically applied. This could be a 1 meter spline, or it could be the surface shown by the contour lines on a geological survey map, with contours every 10 feet of elevation or whatever. It is hard to picture measuring up and down every stump, tree, crevice, dirt clod, and gopher hole. If it rained and there was mud, the area would decrease. When the mud dried and cracked, the area would vastly increase. If plowed, the furrows and clods would increase the microscopic area. It just seems arbitrary and difficult to replicate or get any agreement on.

Least likely place for an earthquake?

on dry land? --Reticuli88 (talk) 16:09, 14 January 2010 (UTC)

Earthquakes tend to occur most frequently on tectonic plate boundaries. However, intraplate earthquakes have occurred (notably, the infamous 1812 New Madrid earthquake which was so strong that it shifted the Mississippi River course). Generally, the regions that are far from tectonic boundaries, and which have minimal historical seismic activity, are the regions where it is least expected to have a major earthquake. There are always caveats - see earthquake prediction for some of the scientific and technical difficulties related to predicting earthquake probabilities. Nimur (talk) 17:21, 14 January 2010 (UTC)

A few G-hits (e.g. [1]) suggest Ireland.--Shantavira|^{feed me} 17:43, 14 January 2010 (UTC)

Although, they had one last week [2] and have had quite a few in the past [3]. Nanonic (talk) 07:28, 15 January 2010 (UTC)

Try any of the white areas: [4]. Dragons flight (talk) 18:09, 14 January 2010 (UTC)

Canadian Shield —Preceding unsigned comment added by 70.81.121.248 (talk) 07:11, 15 January 2010 (UTC)

Australia! --220.101.28.25 (talk) 17:52, 15 January 2010 (UTC)

That map suggests that Australia is at fairly low to moderate risk for an earthquake, but not as low as some other areas such as central Canada, eastern Brazil, Siberia, Sahara Desert, central Southern China, western Congo, etc. ~AH1^(TCU) 03:36, 16 January 2010 (UTC)

Well, I have to admit to a COI, living in Oz. But it is a lot safer than many places. Sydney has the disadvantage of being opposite New Zealand, so if NZ had a big quake a Tsunami is possible. That's a point our OP may not have thought of. You may be safe from a local quake, but if on the seaside a distant one can still get you. See Quakes in Australia, more than I thought but not many deaths. Except for 1989 Newcastle earthquake, and I easily felt that in Sydney. --220.101.28.25 (talk) 07:53, 18 January 2010 (UTC)

Entomophobia

I think I already know the answer, but why doesn't my entomophobia include butterflies and ladybugs? Anything else sends me to hysterics. --Reticuli88 (talk) 16:11, 14 January 2010 (UTC)

Entomophobia is a psychological (medical) condition. You are asking us to help further diagnose your entomophobia. We cannot diagnose you over the Internet. -- kainaw™ 17:16, 14 January 2010 (UTC)

Isn't that a moot point? The OP is asking why xe doesn't go into hysterics when xe sees ladybugs and butterflies. Is reacting normally to butterflies and ladybugs considered a medical condition? 219.102.221.49 (talk) 07:44, 15 January 2010 (UTC)

Isaac Asimov's Foundation Series : The Mule

• SPOILER*SCI-FI NOVEL, In the series The Mule conquers The First Foundation, then on his search for The Second Foundation, his powers becomes neutralized. Did The Mule in fact defeat The Second Foundation? In a World, or rather Universal sense, and in the novel, no he does not. I think in his own personal search for identity he does. He uncovers that there is a Second Foundation. And in that is the victory. I put this question to the Science refdesk because maybe most of you read this a good 20 years ago. Cheers, --i am the kwisatz haderach (talk) 16:58, 14 January 2010 (UTC)

Everyone knew that there was a second foundation. Hari Seldon mentioned it in the first book. Do you have a question, or did you just come here because you wanted to tell someone your interpretation of the novel? — DanielLC 17:09, 14 January 2010 (UTC)

My question is did the Mule win? --i am the kwisatz haderach (talk) 17:26, 14 January 2010 (UTC)

Well our article on Mule (Foundation) says he found the Second Foundation, was neutralised ("turning him into a relatively harmless individual, lacking ambition, and no threat to the Seldon Plan") and died in his thirties. I don't count that as a victory. Nanonic (talk) 17:42, 14 January 2010 (UTC)

He was manipulated into believing he had uncovered and conquered the Second Foundation, but in reality, some SF volunteers sacrificed themselves to safeguard the rest. Heck, he didn't even get the girl. For a kwisatz haderach, you're rather uninformed. Clarityfiend (talk) 00:16, 15 January 2010 (UTC)

Spoiler Alert. Entire Foundation series sumarized in 1 paragraph. If you don't want to know what happens, don't open.
The following discussion has been closed. Please do not modify it.
The Seldon Plan is to Asimov's Foundation series what the Three Rules of Robotics is to his Robots series. It's a literary McGuffin. The whole point of the Seldon Plan is to introduce dramatic tension when it gets broken. Of course, the so-called "Seldon Plan" and the "Encylopedia Galactica" was really a bit of social engineering since Seldon's real plan to preserve civilization involved the "Second Foundation", which controled the universe using "psychic powers". Of course, we learn in the later-written sequels that there were even MORE layers of control, such as "Gaia" (from Foundation's Edge) and a "blast from the past", R. Daneel Olivaw from Foundation and Earth. Basically, each book sets forth a new "control" which believes itself to be in charge, but which we learn in the NEXT book that some even MORE powerful force is controling it all, until we get to the point that the entire universe is basically being run by a several-thousand-year-old robot detective. So, In foundation, we are led to believe that the First Foundation is somehow going to run the galaxy according to the Seldon Plan. In Foundation and Empire, we are led to believe that the Mule ruins the Seldon Plan, and now HE is going to run things. In Second Foundation, we are led to believe that the First Foundation was a ruse, and the entire thing is being run by the Second Foundation. In Foundation's Edge, we are led to believe that it's all being run by a hyper-intelligent planet called Gaia. And finally, in Foundation and Earth, it turns out that the entire system, from Seldon, to the two foundations, to Gaia and the Mule and all of it, is being controled by R. Daneel Olivaw, who takes the Laws of Robotics, especially the "No Robot, through action or inaction, shall cause harm to a human" WAY too seriously, and thus takes it as a categorical imperative to save Humanity. --Jayron32 18:24, 14 January 2010 (UTC) The 3 Laws of Robotics and the Seldon Plan are very far from being MacGuffins. Have you read the MacGuffin article? Most of the Asimov plots deal with corner cases, avoiding them, and the Laws' and Plan's collision with unavoidable reality. Actual MacGuffins (despite the George Lucas quote in that article) are not really interacted with in the story. Comet Tuttle (talk) 19:39, 14 January 2010 (UTC)

Per Wikipedia:Spoiler, that section should not be hidden. Nimur (talk) 19:33, 14 January 2010 (UTC)

I don't agree - that page is about articles. Comet Tuttle (talk) 19:37, 14 January 2010 (UTC)

what if my mom dies

im a 19 yr old male my mom has high blood pressure and other heart problems and is about 62 i have alot of joint problems and need her help for transportation, groceries ect. i have no other family. if she went i would be alone. also if i got really sick i would have no one to take care of me, or after surgery —Preceding unsigned comment added by 67.246.254.35 (talk) 17:05, 14 January 2010 (UTC)

What is the question that you want answered? If you are looking for social support services in your area, we need to know what that area is. -- kainaw™ 17:06, 14 January 2010 (UTC)

The OP's IP address locates near Rochester, New York. The New York State Department of Health and the Monroe County Department of Human Services are the relevant places to check if you have a health-care, psychological, or other crisis you can't handle on your own. If you have a specific medical need, you will need to discuss that with a professional or medical doctor; we can help you locate government services in your area to match you with your needs; but we can't provide medical advice. If you are invalid or have low income, you may qualify for Medicaid (medical coverage paid for by the Federal and State government) in the United States. The Medicaid General Information website is another resource you can check for information. Nimur (talk) 17:13, 14 January 2010 (UTC)

the gov agencies arent helpful also i would still be alone —Preceding unsigned comment added by 67.246.254.35 (talk) 17:18, 14 January 2010 (UTC)

The government agencies are helpful, but they only help in certain specific ways. As for the solitude, we are all alone. Some of us are just less bitter about it than others. Perhaps you could get a cat. Nimur (talk) 17:24, 14 January 2010 (UTC)

I'm afraid that cats cannot provide the same level of companionship that a dog can. Therefore, I recommend that the poster gets a dog (and a girlfriend, then a wife). Trust me when I say that the girlfriend will be more than happy to step in where their mother left off, for better or worse.--Drknkn (talk) 12:22, 15 January 2010 (UTC)

You should speak with your doctor about how to get help if the above happens. Your doctor will know how to hook you up with the appropriate support services. Comet Tuttle (talk) 17:27, 14 January 2010 (UTC)

what services are available? how will i get food or run errands theres no bus route near my house and the nearest store is 10 miles away —Preceding unsigned comment added by 67.246.254.35 (talk) 17:41, 14 January 2010 (UTC) also as for the we are all alone comment most of you have families u can fall back on

There are services in many places like Meals on Wheels that can help, and many places have special bus services that basically do door-to-door pickup and dropoff like a taxicab. Again, you should talk to your doctor, who will know way more about these services in your area than we do. Comet Tuttle (talk) 17:56, 14 January 2010 (UTC)

I really feel for you. My son just turned 19 and I can't imagine how he would cope under those circumstances. If you were younger, a foster home would be the right answer - but at 19, you're close enough to being an adult that you may just be better off to become one. You're going to have to do a lot of growing up in a very short time. Getting over the immediate grief and all of the funeral arrangements will be hard enough - but you've really got to consider what happens after that. You'll need to consider where you get income (get a job - or stay in school - get a student loan?) - what transportation you need (learn to drive - you'll presumably inherit your Mom's car - meanwhile, get a bike). If you have other - even quite distant living relatives - or perhaps even your Mom's neighbors or friends - or parents of your friends - get them involved. Don't be afraid to ask for help. A little help (like a ride to the store to get groceries once a week) would go a long way at this stage. If your mother has life insurance and owns her own home, you'll have plenty of money to get you over the immediate crisis...if not, it's going to be harder. You'll have a lot of skills to learn - some will be a pleasure: cooking, perhaps if you haven't had to do that before can be fun - others less so (when was the last time you had to clean the toilet?!). You'll find that there are all sorts of small, unexpected things that you've not thought about doing for yourself...paying taxes, water and electric bills, for example.

If/when your mother knows that the end is near for her, you're going to need to ask her where the important paperwork is. Insurance policies, house deeds, bank account details, car title, her social security number (or whatever you have where you live). The more fully organized you can be - the better.

If you need more help and advice, (and I'm sure you will if your worst fears are justified) then this is perhaps not the best place for it. However, if there is any help I can offer, please go to my user page here on Wikipedia (User:SteveBaker) and look at the menu on the left where it allows you to email me directly. SteveBaker (talk) 18:04, 14 January 2010 (UTC)

As a further issue, 19 years old is certainly "of age" for getting a job. If there is no health reasons why the OP cannot work, then he could perhaps find a job. Start saving money, and live within your means. By the time I was 19-20 I was mostly self-supporting, financially speaking, and definately by the time I was 21 I was fully self supporting. I certainly had the emotional network I in my family, so I cannot speak to that end of the OPs problems, but financially there's little reason why a 19-year old could not meet their basic needs (food, shelter) with a job. --Jayron32 18:08, 14 January 2010 (UTC)

The OP says he has a lot of joint problems. Depending on the nature of those, they might make getting a job difficult. If so, there are Social Security payments available to the disabled - a doctor would be the best person to talk to for advice on that. It is often possible to find a job even with a physical disability, though. While joint problems may make Steve's idea of riding a bike not an option, learning to drive may well still be possible. My advice to the OP would be to talk to his mother about these worries. While talking to your mother about her own death isn't very pleasant, it probably is the best way forward - ill parents are usually very concerned about what will happen to their children after they're gone, so she'll probably be worried about the same things. --Tango (talk) 18:38, 14 January 2010 (UTC)

i cant get a job because of my joints also who will take care of me if i get sick —Preceding unsigned comment added by 67.246.254.35 (talk) 18:41, 14 January 2010 (UTC)

A lot of people think they can't work because of a disability, but it often isn't true. You can clearly use a computer - a lot of jobs don't require anything more than that. You may be able to work from home if travelling to work would be a problem. If you really can't work, then the welfare state will take care of you, as it will if your condition takes a turn for the worse - there are all kinds of systems in place to help people in your situation. You doctor can help you find out about them. I know it is scary, but try not to worry - the help you need is, and will be, available. --Tango (talk) 18:46, 14 January 2010 (UTC)

I have to say that I think it's great that you're asking this, and not just pushing the thought out of your mind. It's a very valid question. Like the others said, ask your community. You are not the first to be in this position. Check the phone book for "help lines", "community support", and that sort of thing. You could also try a local Chamber of Commerce. If yours are anything like mine, they're involhttp://bits.wikimedia.org/skins-1.5/common/images/button_link.pngved in all facets of the community. If you're embarrassed to ask, you can phrase the question around just wanting to become more independent and take some workload of your mom. Good luck. 75.152.185.94 (talk) 01:42, 15 January 2010 (UTC)

If you would be truly alone in that case (and here's hoping that won't happen), then perhaps you could consider moving to a big city where there would be: public transportation, perhaps better social services, maybe more people who are in the same situation you are, increased opportunities to meet others, more jobs, etc. It sounds you live now in a small town or even in a rural area. If that's not the case, then try moving to a better big city. Just a suggestion... TresÁrboles (talk) 04:23, 15 January 2010 (UTC)

but who will take care of me if im sick —Preceding unsigned comment added by 67.246.254.35 (talk) 12:09, 15 January 2010 (UTC) --67.246.254.35 (talk) 12:10, 15 January 2010 (UTC)

Well I don't know about the healthcare situation in the US, but here in the UK your Disability Living Allowance can be spent on buying care, which can mean you pay someone to do your shopping for you, or you can buy in a rota of live-in carers. If you were in the UK that would answer your question. As you're in the US you will need to bite the bullet and consult either the relevant government agencies referred to above, or if there's a public advice facility similar to Citizens Advice Bureaux in the UK, ask them. They will know the local situation much better than a bunch of jerks on the internet! --TammyMoet (talk) 14:10, 15 January 2010 (UTC)

Depends on the meaning of sick. Medicare / Medicaid and other social services (which you may qualify for depending on the nature of your disability / illness / poverty) often provide for services like hospital care and home nursing visits. Almost certainly, you should expect less attention than your mom would provide, but the state will help ensure you aren't in danger due to lack of basic care. In cases of prolonged disabilities that make you unable to care for yourself, and in the absence of any other care giver, people can also enter nursing homes which would provide for regular attention. Your doctor and local social services office should be able to give you a better idea of what's available and what support you would qualify for. Dragons flight (talk) 14:19, 15 January 2010 (UTC)

If you would need some means of companionship while recovering from something, I would also suggest that you locate a good church or perhaps a club - I don't know how organized the YMCA is but they may have areas where you can socialize and make friends. Call around and see what civic organizations have transportation.

Also, you obviously went to school somewhere. Did you make any friends there? Look them up. I would hope that a decent sized-school would have some people who were, if not really friendly toward you, at least indifferent. True, many may be off to college at your age, but some might be int he area who remember you. Even if the classmate is off to school, often they may have parents who would come look after you.

Which brings me to another possibility. How are you at cleaning, watching younger children, etc.; if you are decent at these, perhaps you could make arrangements with one of those above classmates' families to stay there for a time when you are sick. In return, you can do any dusting and other cleaning and help out in other areas around the house. Your joint problems may or may not be severe enough to prevent you from mowing lawns, but herpahs you can learn to be a handyman and fix things around a house.

It's all about making contact with friends. I know a good friend who met his now best friend at church, and he's over there a lot on weekends, has helped with the niece and nephews who live there with my friend's elderly parents, and has really been taken in as a member of the family. Don't think that nobody will have compassion on you, because they can. You just need to call around to these various friends and ask, "Would you be able to help me if I was sick," etc.. Or, go to a church, as my friend did, and let someone offer their help there. You might need to ask, of course, but there could well be a family like my best friend's.209.244.187.155 (talk) 14:03, 16 January 2010 (UTC)

Bad Electrical Outlet?

A while back the power went out in my room. Simply flipping the circuit breaker didn't work. I haven't done much about it, I just plugged everything in my room into different parts of the house with extension cords, but obviously that's not a permanent solution. My theory is that one electrical outlet in my room is bad. (Being that I'm not an electrician I'm not even 100% sure what I mean by bad.) Here's the thing: The outlet in question has had a window air conditioner plugged into it for a little over a year. The instructions for that air conditioner said to plug it into a single outlet circuit, which I assume I didn't do because there are other outlets on that circuit. One day, the AC kicked on, the lights flickered, and the power went out in my room. Now, one problem is that I'm not sure which circuit breaker controls my room, but I turned off the one I thought it was, so that I could try taking a closer look at the outlet I think is bad, but when I pulled it out of the wall to look at it, I got what I assume was an electric shock. (I can't say for sure, because I've never been electrocuted before, but it definitely made my hand tingly.) So my questions are:

A - Is it possible that one bad (blown, burnt, whatever) electrical outlet could cause all the others on the same circuit to stop working? B - If, obviously, there's enough power getting to the outlet to (luckily mildly) electrocute me, what would account for the fact that, when I plug something in to the outlet, it doesn't work? Digger3000 (talk) 22:39, 14 January 2010 (UTC)

Yes, this has happened to me, where the low-quality outlet itself "wore out" and would cause the whole circuit to go down when I plugged something into it — or jiggled it. I had an electrician come out, verify the problem, and replace the outlet, and since you are unfamiliar with all this, you should probably have an electrician do this, too. Tip: Before mucking around with your outlet, flip off the power to that outlet via its circuit breaker. This way you can avoid death. Comet Tuttle (talk) 22:46, 14 January 2010 (UTC)

Regard that outlet you have opened as dangerous to touch and take the shock you received as a lucky - as in "non-fatal this time" - warning. You need an electrician. At the very least you need someone with the knowledge to use a Multimeter for AC or a Test light (you can get them built into a screwdriver but don't confuse this with similar screwdrivers for testing car 12V circuits) to identify immediately which wires are "live". The fault may be that only one of the mains connections to the suspect outlet is broken, which would explain the outlet not working i.e. being "bad" as you say, but still giving you a shock. One thing you can do is identify which outlets are fed by which circuit breakers just by plugging "something" into each outlet in turn. But you must avoid touching any metal part of the suspect outlet whether you think it is "live" or not. Cuddlyable3 (talk) 23:04, 14 January 2010 (UTC)

A "single outlet circuit" is usually required for an appliance that will draw enough current to reach the limit for a circuit. A bedroom circuit might be wired, for example, assuming the sort of things being plugged in are small (lamps, radios). Many plugs are linked into a single breaker with this in mind. An air conditioner hogs the limit, so even adding a small lamp could blow the breaker.

I should also add that if you've now got your air conditioner running plugged into a "cheapy" extension cord, you should probably think again. Floppy low-priced extension cords intended for something like a lamp are not designed to handle something like an air conditioner. It's a situation that can start a fire. 75.152.185.94 (talk) 01:52, 15 January 2010 (UTC)

The crucial thing here is to find the right circuit breaker and turn it off. If you are 100% sure you've gotten the right one - then you can safely pull the wall socket apart and see what's gone awry. It's likely to be either a wire that's come loose (which you can fix in two minutes flat with nothing more than a screwdriver) - or it's a burned out wire, or a broken wire. If you've lived a good life - it'll have burned out someplace where you can see it...if not, this is going to be a lot of hassle. But my concern is that you may not be 100% sure which circuit is which - and therefore you might switch off the wrong circuit breaker and start working on a live outlet. That can be a life-terminating thing - so in all honesty, while I'm very much in favor of a "Do It Yourself" approach, this may be the time to call the electrician. SteveBaker (talk) 02:25, 15 January 2010 (UTC)

Had something very similar happen last week and the problem was that the circuit breaker went bad, so it could be more then one possible problem here. Googlemeister (talk) 15:44, 15 January 2010 (UTC)

You have my sympathy for getting an unexpected electric shock. I hate getting electrical shocks. They can easily kill you. If you have no idea what you are doing, and no way to determine that the circuit feeding the bad outlet is dead, you should go with the electrician option. The outlet could have failed, or a connection to it could have worked loose, either in the outlet or in a connection at a different outlet in the circuit. If the outlet does not power up things you plug in, but it still shocks you, the problem could be in the neutral connection. In old wiring, I have seen neutral connections so overloaded the insulation burns off. Certainly, bad wiring has the potential to cause a fire, as does your use of extension cords to power the air conditioner. One possibility would be getting the electrician to provide a dedicated circuit for the air conditioner, besides restoring the bad circuit. Edison (talk) 17:26, 15 January 2010 (UTC)

Actually Im not using an extension cord to power the AC, just might light, tv, computer, etc. The AC instructions said not to use an extension cord, and it's January so (luckily) I don't even need the AC now. But eventually it'll get to be spring / summer, so that's why I'm trying to fix this now. Digger3000 (talk) 13:41, 16 January 2010 (UTC)

I occasionally get a shock from the capacitor in my laptop when I pull the power supply plug out carelessly and touch both pins, but if your shock was from the AC supply (rapid pulses, not just a single small pulse of pain) then you must consult an electrician. Don't be tempted to fix it yourself unless you really know what you are doing. Your air conditioner may well draw ten amps. It takes much less than 1% of that current to kill you! Dbfirs 21:46, 17 January 2010 (UTC)

How long to pedal to the moon from Orbit?

So if you were already in orbit around earth and riding a stationary bike that somehow converted the force you pedal into it into acceleration toward the moon, how long would it take to pedal there? This isn't homework, I'm just interested... Note: my thinking is "very short period of time", since there is no friction you could just keep accelerating with the energy (until you reached relativistic speeds). Thus if I can bring myself from stationary to 15 mph in about 15 seconds (I mean at a rate I could keep up for hours), a fit rider should be able to keep adding to the speed, getting to 30 mps in 2 minutes, 300 mph in 20, 3000 mph in 200 minute (about 3 hours), and about 30,000 mph in 30 hours, and the moon is only 238,000 miles away, so at the rate you're going after 1.25 days you can cover the distance in 8 days, or the rate you're going after 2.5 days you could cover the distance in 8 days, or at the speed after 5 days, in 4, for a total of nine. No doubt someone could invent mathematics to figure out the total time it would take, bearing in mind tha you are cotinually accelerating, but until that mathematics is invented a good upper bounds is the 5 days you will take for the WHOLE distance plus the 4 days it took to pedal to that speed, for a total of 9 days. Obviously with Future Math X we could figure out exactly how much less than 9 days it is, but for now my hunch is that it's less than a week. So, my thinking is, from Orbit, you could pedal to the moon in less than a week... Am I right?85.181.144.112 (talk) 23:17, 14 January 2010 (UTC)

See the article Bicycle brake systems. Cuddlyable3 (talk) 23:21, 14 January 2010 (UTC)

in my hypothetical question I was just thinking crashing into the moon at full-speed at the end... 85.181.144.112 (talk) 23:37, 14 January 2010 (UTC)

Check out trans lunar injection, as well as Hohmann transfer. The first article says that a delta-v of about 3.2 km/s is needed. I guess that'd be doable on a bike, given enough time. Buddy431 (talk) 23:52, 14 January 2010 (UTC)

You are assuming constant acceleration. Maybe your magic bike does that, but I'd suggest a more likely model is constant power. That's the model that would make sense if you envision the rate at which your feet move being constant as they push against some resistance of fixed intensity. It would still be magic, but slightly less silly magic. Anyway, a constant power model would imply that for each factor of X increase in speed you need to keep working for X*X amount of time. So if 3 mph takes 2 minutes then 30 mph takes 200 minutes, and 300 mph takes 20000 minutes (300 hours or 12.5 days). Obviously this approach would take much longer than a week. Dragons flight (talk) 00:29, 15 January 2010 (UTC)

Actually, in space, constant acceleration is more likely that constant power. To propel yourself you need to throw something backwards. How much you accelerate depends on the mass of your exhaust and its speed relative to you. That last point is key - it doesn't matter how fast you are going relative to the Earth since the Earth isn't involved (its gravitational field is, but that doesn't make any difference to this), the speed of your exhaust relative to you will usually be constant, meaning you get constant acceleration. That is why the difficulty of getting from A to B in space is usually measured using delta-V, not energy. How much energy it will take to get a certain amount of delta-V will depend on how you do it (firing your engines at periapsis, closest approach to a massive body, is usually most efficient since you'll be moving fastest relative to that body and an extra metre per second at high speed gives you more extra energy that at low speed due to the square in the formula for kinetic energy). --Tango (talk) 01:08, 15 January 2010 (UTC)

Tsk, tsk, Tango, that would be a rocket to the moon, and we want a bicycle.  ;-) Seriously though, that's only constant acceleration to the degree that the total mass loss of the rocket ship is constant, otherwise it is increasing acceleration. Anyway, we appear to have different brands of magic bikes. My magic bike conserves it's mass and somehow pushes against the "ether". Dragons flight (talk) 01:32, 15 January 2010 (UTC)

Sure, if you go totally magical then the laws of physics don't apply. There is no need to, though. Just use the cycling to power an ion drive. The mass of the exhaust is very small for such a drive, so mass is effectively constant, so you will get pretty constant acceleration (you do have to factor in gravity at some point, but as long as you start from a fairly high Earth orbit, like geostationary orbit, you're most of the way to the moon anyway in terms of gravitational potential energy). --Tango (talk) 01:44, 15 January 2010 (UTC)

This suggests that an average person can generate about 150 watts for an extended period of time on a bike. Our ion thruster article doesn't list any ion drives that consume power in that range, though. Can anyone find a suitible one to use? Otherwise, it looks like the ones listed are getting about 0.2-0.4 mN per watt. If we assume a 100 kg person, supplying 150 W for a total thrust of 6 mN, that gives us an acceleration of 0.00006 meters/s/s. If we want a delta-v of 3200 m/s, we come up with 53,333,333 s, which is about 617 days. Someone want to check my math? Buddy431 (talk) 02:15, 15 January 2010 (UTC)

OK - so this is the science reference desk - and magic bikes are right out of the question. So let's get real: You can't use the speed of a typical bike wheel to propel material out the back of your bike because at that appallingly low speed, the amount of propellant you'd need would be crazy. You need some electrical help. You need to stop off at http://www.econvergence.net/electro.htm and pick up one of their electrical generators for stationary bikes. This will get you 300 Watts at 12 to 25 volts for as long as you care to pedal. Now we need a rocket engine that we can drive electrically because using rocket fuel would be using chemical energy and that's cheating. Clearly we're not going to want to haul a lot of propellant around - so an Ion drive would be the thing to aim for. These gadgets use electrical power only to accelerate charged particles at extremely high speeds. That gives you the best amount of thrust for the least amount of propellant. Sadly, the table in our article says that a fairly minimal ion drive needs 2.3 kWatts...so either we're going to be charging up batteries for 10 hours in order to get 1 hour of propulsion - or we need something yet more exotic. The one candidate is the 'FEEP' Field Emission Electric Propulsion which will happily produce one milliNewton of thrust for a mere 60 Watts - you're going to need to step up your 12 volt power up to the crazy high voltage the FEEP needs - but that's do-able. So five FEEP's bolted to our bike frame is the way to go here. Sadly, that 5 milliNewtons means that we're going to have to keep the mass of our craft to extremely modest proportions. F=ma so our acceleration will be F/m and F=0.005. If our craft were to weigh about the same as a small car (let's say 1000kg) then we're going to be accelerating at 5 millionths of a meter per second per second. We need to be moving at 3.2 km/sec so we're going to need to pedal for about a billion seconds - 30 years if you don't take a break. You'd be looping around the Earth, gradually increasing the radius of your orbit as your speed increases. But now you have to worry about how to fit 30 years worth of food, water and oxygen into your 1000kg mass budget. Also, although the FEEP doesn't need much propellant compared to Saturn V type rockets - the amount it would need to thrust continually for 30 years wouldn't be negligable. I don't think we're going to do it. SteveBaker (talk) 02:05, 15 January 2010 (UTC)

So either 2 years using my optimistic mass and thrust, or 30 years using Steve's less optimistic mass and thrust. Like he said, it's not going to happen. Buddy431 (talk) 02:22, 15 January 2010 (UTC)

Perhaps what's needed here is a space elevator, and a bicycle powered elevator cart. I'm not quite sure how you'd get from an Earth space elevator, to a Lunar space elevator, but let's take this one step at a time. 100,000km is often thrown about as a theoretical height for an Earth space elevator so that's a good height to shoot for. Let's make some generous assumptions here.

• • Your bike and yourself (And your space suit) are a remarkably light 100kg. (200lbs)
  • You are capable of pedaling at ¼hp, the same power required for the Gossamer Condor. (I hope you're an Olympic level cyclist!)
  • You don't need any food or water or anything.
  • The effect of the moon's gravity is negligible. (I'm pretty sure it is.)

Some quick back of the envelope calculations show me that you could reach the top of the space elevator in a nice and tidy 365 days of non-stop pedaling. Let's say two or three years of "realistic" times. (Someone correct me if I've done these calculations wrong, that's very likely.)

Once you're in high Earth orbit you could somehow (magic?) get to the top of the Lunar space elevator, and I imagine you could get down to the moon without any serious pedaling. Once you got moving you'd pretty much just need really good brakes.

The advantage to my plan over Steve's is that you could stop pedaling at any time to take a rest and not have to worry about plummeting back down to Earth. You might not even need to take all of your food, water, and air with you! You could have other people send (powered) robots up the elevator cable and deliver your supplies to you. (You might consider this cheating, but it's OK to hand a drink to a marathon runner, so why not?)

The disadvantage to my plan is that unlike Steve's FEEP thrusters, the space elevators haven't been built yet, and probably won't be in our lifetimes. APL (talk) 06:02, 15 January 2010 (UTC)

1) "you were already in orbit around earth" - What orbit? You could be at a Low Earth orbit, a Geostationary orbit (36,000km above sea level in the plane of the equator) or you might be already on the Moon which happens to be in orbit about 384 000 km away. If the latter, just park your bicycle.

2) You talk about uniform acceleration in a straight line. Calculate the distance travelled "s" from this formula (for which you don't need Future Math X):

                           2
         s  =  u t  +  a  t
                       ----
                        2

where u = starting velocity, t = time, a = acceleration

3) You are changing from one orbit to another so you won't travel in a straight line anyway.

4) Top Bicycle gearing ratio on a racing bicycle is around 125 and if you are fit enough to pedal at 120 rpm (try it) you go 45 mph.

5) "you could pedal to the moon in less than a week" Yeah, r-i-ght. Cuddlyable3 (talk) 11:59, 15 January 2010 (UTC)

Once you reach geostationary orbit on a space elevator you would actually start to "fall" up the elevator, so you only need to get that far. Then you can fall up the rest of it, building up speed and fly off the end. If you time it right, you'll fly off towards the moon. --Tango (talk) 17:04, 15 January 2010 (UTC)

I guess that would work if you're content to plummet down onto the moon at a zillion miles per hour. APL (talk) 17:45, 15 January 2010 (UTC)

The OP explicitly said a crash landing at full speed was acceptable. --Tango (talk) 02:20, 16 January 2010 (UTC)

Oh. You're right. APL (talk) 01:45, 17 January 2010 (UTC)

If you're pedaling towards the moon, you'll never get there. You need to pedal in the direction you're moving along the orbit. — DanielLC 18:31, 15 January 2010 (UTC)

I think that if our questioner were to simply pedal east he would probably fall into an ocean before he reached the Moon. APL (talk) 02:03, 16 January 2010 (UTC)

Pedalling forwards would generally be more efficient, certainly, but pedalling directly towards the moon would work as long as you only pedalled at the right times. I can't work out when the right times would be, though... The half an orbit when you are closer to moving towards the moon than away from it, I think. --Tango (talk) 02:01, 17 January 2010 (UTC)

Quickest way of dissolving steel

I need to know a solution to dissolve stainless steel as quick as possible. It dissolves quite good in copper solution of aqua regia. Maybe you know more efficient ways of doing this? Renaldas Kanarskas (talk) 23:35, 14 January 2010 (UTC)

Are there any physical constraints, such as pressure and temperature? Could it be dropped it into a very hot crucible of "solvent" metal, like in an electric arc furnace? (When would such a mixture be an alloy and when would it be a "solution?") Also, there seem to be varying types of Stainless steel. Edison (talk) 17:13, 15 January 2010 (UTC)

Even without submerging it in molten metal as a "solvent", I would assume that higher temperature might allow other reactants to act quicker on the steel. Is it required to dissolve it, or is it sufficient to chemically attack it or oxidize it? If it is heated red hot and exposed to pure oxygen, it should rapidly oxidize and leave its solid form, like with a cutting torch (don't try this at home). Edison (talk) 13:48, 16 January 2010 (UTC)