Wikipedia:Reference desk/Archives/Science/2010 January 28

= January 28 =

Circuit simulation
Hi all,

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

Any ideas on how to stimulate this circuit?

Thanks! 93.104.54.89 (talk) 02:53, 28 January 2010 (UTC)
 * That circuit doesn't really need to be simulated. It can be directly solved.  SPICE and other circuit simulators are awfully complicated - much more complicated than actually solving this circuit by hand.  Have you looked at series and parallel circuits?  You can directly solve for the total resistance, and then solve for the total current, and thus, by applying Ohm's law, calculate the voltage at every node.  Do you need help with this procedure?  If you really want to, though, you can write a netlist and SPICE can give you the voltage at each node.  Nimur (talk) 03:39, 28 January 2010 (UTC)
 * I am trying to write a simulator - the above-mentioned circuit just showed what I meant with nodal analysis - I am stuck. I can't figure out how to handle the split after R1 in a simulation :( I tried to understand SPICE and GnuCap source, but both are totally unreadable and uncommented. 93.104.54.89 (talk) 04:02, 28 January 2010 (UTC)
 * R2 and R3 are resistors in parallel, so you use the formula to determine the total resistance of 2 parallel resistors, and substitute R2 and R3 with a single value for that resistance. Do you need help with calculating the value of the resistance from R2 and R3? --Phil Holmes (talk) 09:43, 28 January 2010 (UTC)
 * Wikiversity can teach you about nodal analysis. Cuddlyable3 (talk) 12:49, 28 January 2010 (UTC)


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

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


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


 * Our Thorium article says there are advocates of same in India, and that there's some experiment underway in Moscow. THTR-300 is an article about the one that used to operate in Germany.  The article is thin on the reasons why it was decommissioned.  Comet Tuttle (talk) 05:57, 28 January 2010 (UTC)
 * Producers and regulators are more used to uranium reactors. Years of operating experience mean that the common problems and their solutions have already been found. For example, Areva claim "several thousand reactor-years of light water reactor operation worldwide" when advertising their EPR. Nobody has that with Thorium reactors.


 * For a regulator's example, "The NRC has developed its current regulations on the basis of experience gained over the past 40 years from the design and operation of light-water reactor (LWR) facilities." (emphasis added) AlmostReadytoFly (talk) 10:00, 28 January 2010 (UTC)
 * This is typical with English speakers: they assume they know everything. The german language article is more informative: there were problems with breakage of fuel rods and with recycling (that's why the one(s) in South Africa are designed differently). Finally, the last accident put a lid on it. --Ayacop (talk) 18:58, 28 January 2010 (UTC)


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


 * True. Also, using load balancing technologies like thermal storage and pumped storage hydroelectricity you virtually eliminate the need for heavy baseline capacity. In 2005, wind was the least expensive form of new power, and while demand economics have intermittently changed that since, wind continues as one of the most profitable power investments, for good reasons, only a few of them having to do with flood costs.
 * Technically, all wind is solar in origin, and all solar power is nuclear. Which is why I think nuclear is a reasonable space power source for melting a comet captured inside an asteroid. Either that or black paint. 99.56.138.51 (talk) 16:34, 29 January 2010 (UTC)
 * Too bad we do not yet have feasible fusion power production like the sun. That makes fission look wimpy.  Of course, if we are imagining, we should go for the gold and try for anti-matter power.  Googlemeister (talk) 21:02, 29 January 2010 (UTC)
 * Not until we can do inertial confinement fusion, which is looking less and less likely all the time, based on neutron emissions. 99.56.138.51 (talk) 17:48, 1 February 2010 (UTC)

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

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

But what would the control be in this case? Is it group III, IV or both of these? Thanks 121.216.118.27 (talk) 03:48, 28 January 2010 (UTC)
 * The control would be group IV, since the placebo effect would be a definate "result" in your experiment. A control sample is supposed to have no results at all.  The belief that one might be taking a drug is itself an experimental variable, so you need a control group which contains absolutely no variables being tested at all.  -- Jayron  32  04:30, 28 January 2010 (UTC)
 * I disagree. A control group needs to have absolutely all the variables the test group has, except the one you are interested in. If what you are interested in is the efficacy of a drug then the control group should be identical to the test group except you don't give them the drug. That means you give them a placebo. --Tango (talk) 04:34, 28 January 2010 (UTC)
 * There isn't usually a "nothing" group in this kind of study. Are you sure there is one for the study you are talking about? The only reason for having a "nothing" group is to see how much impact the placebo has. I do remember a study on anti-depressants that tested the drug, a placebo and nothing that had quite an interesting result - the improvement patients on anti-depressants showed was apparently 50% them getting better naturally, 40% placebo and only 10% the drugs (or numbers like that, I forget the exact figures). Most trials don't bother assessing the effectiveness of placebos, though. In fact, they often don't even include a placebo group and just compare the new drug with an established drug. That way you aren't making a third of your subjects go without treatment, which is rather unethical, and you really only need to know if the new drug is or isn't better than the existing one. If it's better than nothing but worse than the existing drug, it's still useless (unless you undercut the price of the existing one, which you usually can't). --Tango (talk) 04:34, 28 January 2010 (UTC)
 * In fact, I'm surprised the placebo is included at all. I was under the impression that commonly an existing and established drug will be used in place of the placebo. Of course with sleeping pills it isn't much of a life an death situation so perhaps they don't bother but then again, unless both are new drugs and the efficacy of neither has been established, it does seem a bit pointless to me. Edit: Ooops reading more closely see you already said that Nil Einne (talk) 08:13, 28 January 2010 (UTC)


 * A control is defined for a specific comparison, not for an experiment as a whole. For the drug1-vs-placebo and drug2-vs-placebo comparisons, the placebo is the control.  For the placebo-vs-nothing comparison, nothing is the control.  I agree that it would be unusual to have both placebo and nothing groups, but it isn't unheard of. Looie496 (talk) 17:17, 28 January 2010 (UTC)
 * For general interest: the use of placebos versus no treatment is found in a modest fraction of studies. It is from these studies that the existence of "placebo effects" have been meta-analyzed-- &mdash; Scientizzle 17:31, 28 January 2010 (UTC)


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

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


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

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


 * That is a statement with a question mark at the end of it, not a question. Are you asking if that statement is true? If so, and assuming I've correctly guessed which of the many possible meanings of "scr" you mean, you may find the answer here: Silicon-controlled rectifier. --Tango (talk) 06:06, 28 January 2010 (UTC)
 * ...where you can read "The device will remain in the "on" state even after gate current is removed so long as current through the device remains above the holding current." which answers your question (if that's what it was). Cuddlyable3 (talk) 12:43, 28 January 2010 (UTC)


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


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

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

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

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


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


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

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


 * Enjoy!


 * Of course there is another problem - extracting the 3D data from a bunch of 2D images requires there to be enough surface detail to make that possible. Also, because specular light will produce highlights in different places in each image.  Because the camera can't really tell the difference between a shiney bit and an actual white patch painted onto the surface - there will always be ambiguity.  But if you have an area of the object that's in deep shadow - there is literally no way to extract depth information from it.  My scanner shines a laser onto the object to try to help this situation out - but it still fails miserably for very shiney objects. SteveBaker (talk) 22:04, 28 January 2010 (UTC)
 * I was considering posting some seismic tomography code, which does generate true 3D volumetric images using sound-waves, but it's pretty impractical for the hobbyist... fortunately Steve's laser scanner is a little more reasonable.  A fun project would be writing an enhanced version of the Scan_Extract script/program.  There's about ten thousand corner-cases I can think of - the simplest is a non-convex object - you have to use a lot of math or program logic to tesselate general-case 3D objects!  Nimur (talk) 02:01, 29 January 2010 (UTC)
 * If you follow the link at the top of my wiki page, you'll find the ScanDraiD project over on SourceForge. That is the result of a bunch of guys taking my Scan_Extract program and doing precisely what you suggest.  Sadly, I don't have the time to actively support that work - but it's certainly a worthy cause for anyone with software skills who is looking for an interesting problem.  The program "as is" produces a crazy-dense grid of points - but because the laser image is continuous, you do have the complete surface shape in the source video...at least in principle. SteveBaker (talk) 02:53, 29 January 2010 (UTC)
 * I know of an application that does something similar to this(first query). The object to be 'scanned' was stationary at the centre of three cameras (one at 9, 12 and 3 o'clock), and a laser line scanner (or projector?) was then moved around the object an a big arm. A Silicon Graphics workstation did the processing, and a PC controlled cutting tool was used to cut a copy of the objects shape. (so it's not a HD or Video application but the principle is similar?) So you probably need at least 3 HD cameras plus a laser projector as also suggested by Steve. 3D scanner may be of some interest--220.101.28.25 (talk) 09:52, 29 January 2010 (UTC)

What's the difference between hairline skin and crown skin?
I saw the minoxidil product at the grocery store and the instructions said "For use on the crown only, not for receding hairline." Why? 20.137.18.50 (talk) 12:54, 28 January 2010 (UTC)
 * I don't know the answer to the first question (difference between hairline skin and crown skin) but the second question about the specific medicine is borderline medical advice (which we don't do here). If you ask a pharmacist, he or she should be able to tell you or direct you.  Hope this helps.  Falconus p  t   c 15:38, 28 January 2010 (UTC)
 * Unfortunately our scalp article is not great at describing why the scalp's skin is much different, and I didn't see what I was looking for in skin either. Falconus p t   c 15:43, 28 January 2010 (UTC)

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


 * Minoxidil is only proven effective for one kind of hair loss, androgenic alopecia. Receding hairline is not the kind of hair loss it has been proven to help. --  k a i n a w &trade; 16:03, 28 January 2010 (UTC)


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


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


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

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


 * Typically, aerobic exercise will increase the effectiveness of oxygen use in the body. The blood will be able to carry more oxygen.  The effective use of the oxygen increases.  So, less blood is required to get the same level of oxygen effectiveness.  Therefore, lower blood pressure is required. --  k a i n a w &trade; 14:32, 28 January 2010 (UTC)


 * Probably there are also simple (but 'uninteresting' for research) mechanisms like helping the movement of the bowel will lower vegetative symptoms from obstipation (lowering release of catecholamines from the sympathic nervous system ).
 * Additionally, keeping a high muscle mass in old age won't let you collect fat in the wrong places (eating less does the same but who really is able to?), leading to the same obstipation with vegetative symptoms. --Ayacop (talk) 18:47, 28 January 2010 (UTC)


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

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


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

Some cathedrals took centuries to build. You do not have to look into the future to decide if they have been finished or not. 89.242.92.249 (talk) 14:39, 28 January 2010 (UTC)
 * The scientific method is not a building. It's not even a "thing"—it's a set of loosely-adhered to methodological strictures that guide particular forms of inquiry. The analogy is poor. There is no "finished state" of methodology. --Mr.98 (talk) 14:47, 28 January 2010 (UTC)


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

So I'll never know if the development of GWBasic is finished or not? Another related question is how long ago the last development in the scientific method was? 89.242.92.249 (talk) 14:54, 28 January 2010 (UTC)
 * According to the article GWBasic's latest version was developed in 1988. There is no good reason to expect any further development now of such a low-performance (interpreted) program for outdated hardware that has no marketing potential, but I think you do know that. That issue is unrelated to the scientific method. Cuddlyable3 (talk) 14:58, 29 January 2010 (UTC)
 * Please cite your hard evidence that it is unrelated, even by analogy. Thanks. 78.149.152.46 (talk) 00:39, 30 January 2010 (UTC)


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


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


 * I don't think the scientific method ever changed, and I find it unlikely that it ever will. True, the ancients attempted to use other means to understand reality - but they succeeded only as far as they used the (modern) scientific method, and failed when they didn't. —Preceding unsigned comment added by 83.134.173.152 (talk) 18:06, 28 January 2010 (UTC)
 * Yeah - and getting past peer-review into the really serious journals was an absolute bitch in the Paleolithic. SteveBaker (talk) 03:37, 29 January 2010 (UTC)
 * I think it's still changing. In very minor ways - the rules for publication in various journals changes fairly frequently.  It's becoming increasingly a part of the scientific method that one publishes data in a machine-readable form so that other scientists can access it.  That was never true even 10 years ago.  But the overall approach hasn't changed much:  We are carefully, step-by-step building knowledge on solid foundations with checks and balances to try to ensure that nobody gets to stick a lump of jello in our slowly growing pile of solid stone slabs.  It's not perfect - but it's by far the best way to get at "The Truth" that humanity has ever found.  But it's not "finished".  Mathematicians have a different standard of what makes a theorem than Physicists have for what constitutes a theory - which is different again from what a paleontologist would accept as proof that a new kind of dinosaur had been found.  But the big picture is pretty much agreed upon. SteveBaker (talk) 21:57, 28 January 2010 (UTC)

The next step may be putting all the information in scientific journals in a way that the meaning can be "understood" by a computer, without a human having to read through them. Like the sematic web. 89.242.37.55 (talk) 01:58, 29 January 2010 (UTC)
 * I made a suggestion to do that with the information in Wikipedia as a part of the Wikimedia strategic planning process...sadly, the suggestion fell on deaf ears. I don't think they understood what I said. :-(  SteveBaker (talk) 02:40, 29 January 2010 (UTC)


 * Paradigms are always changing, as are scientific theories and ideas. For example it took 70 years for geologists to accept Alfred Wegener's then-new idea of continental drift which has evolved into the currently-accepted plate tectonics theory. ~ A H  1 (TCU) 03:12, 29 January 2010 (UTC)
 * Edited from "Wagener" to "Wegener" to change the link from red to blue: hope this is not deemed excessively presumptuous. 87.81.230.195 (talk) 10:06, 29 January 2010 (UTC)
 * You are NOT ALLOWED TO EDIT OTHER PEOPLES POSTS - PERIOD. Please read the ref desk guidelines and don't do it again.  How do YOU know that AstroHurricane didn't actually mean someone called "Alfred Wagener" and now you've screwed up his post.  You're are perfectly at liberty to create a response that says "Hey didn't you mean "Alfred Wegener"?" - but you must not edit other people's posts.  The only exception is to fix egregious formatting errors that cause disruption to the readability of the ref.desk pages. SteveBaker (talk) 20:11, 29 January 2010 (UTC)
 * 87.81.230.195 made a helpful correction where the context makes it clear that AstroHurricane001 really was referring to Alfred Wegener who IS the originator of the theory of continental drift, and 87.81.230.195 should be credited for politely explaining exactly what was changed such that no knowledge of AstroHurricane001's post has been lost. To accuse 87.81.230.195 harshly of "screwing up" AstroHurricane001's post is unwarranted. One can draw attention to a guideline without making a rant about it. Cuddlyable3 (talk) 23:47, 29 January 2010 (UTC)

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

- SteveBaker


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

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

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


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


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


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

Did I say Tobacco? Nay, just Smoke. I said smoke because I didn't want to bring in the entire druggy-lifestyle-is-cool-man motif, but since everyone is quick to think nic, lets say, you're smoking weed. Smokestuffs could be Marijuana cigarettes. --i am the kwisatz haderach (talk) 20:02, 28 January 2010 (UTC)
 * Even if you forget the drugs entirely and smoke, lets say, lawn clippings, It doesn't really change the health situation much. Your homegrown theory that it will stimulate your immune system, make you immune to certain chemicals in your food (Why would it only be the bad chemicals that you'd be immune to, by the way?), or "get your mind right." is completely false.
 * By the way, you seem to be under the impression that your immune system protects you from "chemicals". This is not generally the case. Your immune system protects against pathogens.  APL (talk) 21:07, 28 January 2010 (UTC)


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


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

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


 * The brain is not simple, and does not function just in terms of good versus bad. Even assuming for a second that smoking helps the brain in some strange way (a concept that I disagree with), it is not like you can easily counter a problem with the nervous system by trying to increase whatever you feel is "good" for the brain.  Even if you have a chemical that is truly good for the brain, there is no reason to suspect that it will do anything to counter the effects of mercury poisoning.  At best, you have done nothing, at worst you have just added poisons to your body that is already not doing so great.  Smoking is proven to add many poisons to one's body.  Note that if your body is stressed (such as by a poison) it is, as I understand it, much more susceptible to cancer starting at that moment.  Smoking carcinogens does not seem like a wise idea ever, especially if you are already sick. Falconus p  t   c 06:22, 29 January 2010 (UTC)
 * And in any case, cigarette smoke contains up to 28 nanograms of mercury per cigarette in a particularly dangerous vapor form. It's certainly not going to help mercury poisoning! SteveBaker (talk) 07:18, 29 January 2010 (UTC)


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

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

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


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

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


 * How limitless? Are we talking about a nuclear reactor that never needs fueling?  Or a magic reactor that can give me any quantity of energy at a moment's notice?
 * For instance, if I built a machine that that needed the entire energy output of a thousand suns, could I just plug it into your proposed free energy machine? Or do I just get regular home electrical current ... but forever without paying a bill?   I don't mean to nitpick, but these details drastically changes the answers. APL (talk) 19:09, 28 January 2010 (UTC)


 * Jerry Pournelle has stated that this would solve all human problems, for starters. Comet Tuttle (talk) 19:23, 28 January 2010 (UTC)
 * He would say that, even though it is patently absurd. Any accomplished SF reader or author should know that once you plug up one source of problems, new ones spill out from unexpected quarters. --Mr.98 (talk) 21:59, 28 January 2010 (UTC)
 * Ok, so switch that to all existing human problems. I'm not sure it's entirely true then, anyway - human nature won't have changed. A lot of conflict is over pride and power, rather than resources. --Tango (talk) 06:46, 29 January 2010 (UTC)
 * So my Susan would finally stop kissing that other guy? An entirely human problem and existing all over the world.93.132.164.32 (talk) 08:15, 29 January 2010 (UTC)
 * If you kill the other guy, or Susan or you get killed then that problem is solved although you may have new ones. Of course you can do that nowadays, but having unlimited energy likely makes it easier for you to deal with the possible consequences. This may not work if the other party uses their unlimited energy for some kind of scifi style energy shield, but we're still a long way from that but could probably design various weapons primarily using energy. The net result may be anarchy and even the destruction of the world which would I guess solve all human problems (no humans=no human problems) unless someone makes it to space in time as we suggested below Nil Einne (talk) 22:49, 3 April 2010 (UTC)


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


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


 * Is your energy source small enough to carry with you? Then you could make personal flying machines. Ariel. (talk) 19:31, 28 January 2010 (UTC)
 * I don't think you would destroy the economy, but you would drastically change it. Basically the only limited resource would be human time, but that would still have value. That means, roughly, that agriculture and industry would disappear (or become really tiny - 1p for a week's food to cover the few humans involved in the process, perhaps), but services would remain (in a much altered form). --Tango (talk) 06:46, 29 January 2010 (UTC)


 * Not limitless by any means, but it would be good if there existed an enzyme that could reduce the activation energy of the reaction 2H2O -> 2H2 + O2. There's a lot of water on our planet and combustion of hydrogen gas can be used to do work. But electrolysis is very energy-expensive. 20.137.18.50 (talk) 19:32, 28 January 2010 (UTC)
 * I really never understood what's so hip about hydrogen. It needs an energy source to free it from oxygene in the first place and than gives nothing but trouble with safety, storing and combustion (volume gets less, not more when burnt). Don't get fooled by the fact that it does not create CO2 when burnt, the CO2 is freed from the primary energy sources needed that provide the energy for creating the H2 out of water. Unless you use atomic energy or have plenty of space for solar energy. In this case it would be far more practical to generate hydrocarbons as energy store. The only advantage of H2 over hydrocarbons is that it can be more easily used in fuel cells but afaik this is because fuel cell membranes are sensitive to contamination and H2 is cleaner than natural occuring hydrocarbons. 93.132.164.32 (talk) 08:08, 29 January 2010 (UTC)
 * You would have limitless energy if you could do that to any significant degree, because you could burn the products, and break the water in a cycle. Of course, that can't happen.  Perhaps you could reduce the activation energy a little bit, but it's the enthalpy of formation of water that's your main problem with electrolysis, and you can't change that by even the tiniest amount.  --Tardis (talk) 20:35, 28 January 2010 (UTC)


 * You would get a serious case of global warning, because where would all that energy go once it was used? Heat. You could melt the Antarctic icecap to make more land (to compensate for all the flooded land) Graeme Bartlett (talk) 20:44, 28 January 2010 (UTC)
 * But the fridges use energy, right? If I had enough energy I could freeze Milky Way (at expense of Andromeda galaxy) (Igny (talk) 20:52, 28 January 2010 (UTC))
 * You could sequester CO2 out of the atmosphere and store it together with some water in its most environment-friendly form as cellulose. No fear of sudden outgassing and plenty of useful things to do with it. If energy is really, really abundant and heat still is a problem, we could do like Pierson's Puppeteers and move our whole planet away from the sun. By the way, terraforming of other planets as well as deep space travel would be in reach. 93.132.164.32 (talk) 07:45, 29 January 2010 (UTC)

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


 * If someone gave me, as a gift, a fully fueled reactor from a nuclear sub, it would be more or less equivalent to someone giving me a free energy machine and then taking it away ten to twenty years later. I'd probably use it to power my TV.
 * That's the problem I have with questions like this. Without defining how you're getting the energy and what it's limitations are the answers could range anywhere from "Crush the entire universe to a singularity and cause a second Big Bang" to "Reheat a frozen pizza". APL (talk) 21:12, 28 January 2010 (UTC)


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


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


 * So my answer is "This is a silly question and we can't answer it" - and I'm standing by that!
 * SteveBaker (talk) 21:43, 28 January 2010 (UTC)
 * Just replace "energy" by "Fusion power plus enough fuel" and reread again. Then notion of Renewable energy wouldn't make sense when "energy" was always used in the strict sense of physics, would it? 93.132.164.32 (talk) 08:24, 29 January 2010 (UTC)
 * The problem isn't how the energy is made - it's the word "Unlimited". Fusion power with finite fuel is far from "unlimited".  Infinite fusion-generated power requires infinite fuel which gets you back to what I wrote.  If the question is merely about large amounts of energy rather than unlimited amounts - then it had better put a cap on how much we're allowed to use.  SteveBaker (talk) 20:07, 29 January 2010 (UTC)
 * Think of "unlimited" in the way natural numbers are unlimited: for any one of them there is a bigger one. And of course, even that is silly because the mass of the universe puts a limit. 95.115.151.113 (talk) 09:45, 31 January 2010 (UTC)

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


 * If I were granted free almost unlimited energy wherever I chose to use it, I would build a starship, bid farewell to Earth, and take a few of my closest friends on a tour of numerous star systems, reaching within a gnat's eyelash of C at peak velocity by maintaining a constant acceleration of about 1 G. Edison (talk) 05:29, 29 January 2010 (UTC)
 * If I gave you a shoebox with an electrical outlet on it, and this outlet could produce as much current as you care to draw, how would you use that to build a starship in your lifespan? APL (talk) 05:37, 29 January 2010 (UTC)
 * Oh - that's easy! You go to the boss of NASA and say "I'll give you this amazing magic box - the study of which will be the saviour of all mankind if, in return you'll build me a starship".  From that point on, things get very silly!  :-) SteveBaker (talk) 07:15, 29 January 2010 (UTC)
 * You can't solve world hunger with food. We grow more than enough food for everyone now, but there are still people going hungry. World hunger is caused by politics, not droughts. --Tango (talk) 06:46, 29 January 2010 (UTC)
 * However free energy can help (note I didn't say solve) some (note I didn't say all) of the problems which cause world hunger at the moment.
 * For example, one of the problems is transporting the food to the right places. This becomes a lot easier with free energy. Of course you may not even need to transport and this gets to another problem which is that many countries are reluctant to rely on other countries for their food supply, many of course can't even afford it. Poor countries are often affected by drought and other problems which cause drastically reduce their food supply. However with free energy sudddenly these problems grow a lot less dire (desalination for example) and it's a lot easier for whoever wants to, to grow whatever food they want.
 * This is all presuming this free energy is widely and easily available and not something people are going to fight over which is perhaps a big if.
 * I would add while this 'we grow more then enough food' thing is a common statement and does illustrate some points and has some truth, it's IMHO a little simplistic.
 * For starters, AFAIK people often tend to include all the grain etc we grow, calculate the energy available from that and say we could provide x kJ to each person per day with this amount of grain. Great in theory. Except of course a large part of it goes to feeding animals. This is wasteful and something recently receiving a lot of attention due to climate change however convincing people to reduce their consumption of animals is not easy and in fact in many parts of the developing world it's increasing as people get richer. So producing more food will make it easier to farm more animals. If you care about animal welfare, you may not like this (although some animal welfare issues could be reduced with free energy), but that's not particularly relevant.
 * There's also the issue of why food goes to waste. There tends to be this belief that a lot of food sits in warehouses and is thrown away because it gets too old. While this is surely partly true, I'm guessing it's also fairly simplistic. People tend to be fussy about what they eat, in parts of the Western world refusing many parts of animals for example, and this combined with food safety requirements mean what may be okay food is thrown away either before it gets to the warehouse or after it leaves (the consumers themselves probably play a big role in that, amongst other things, reasons of convenience means people tend to buy more then they need).
 * Food processing does enable the use of parts that seem unappertising however that costs including in energy and changing consumer demands is potentially reducing our ability to do that. And people tried to use bone meal as feed to reduce waste, look how that ended up...
 * In other words, the waste is coming from multiple areas that aren't easy to resolve and it's not so easy to just send it to starving people even ignoring distribution issues. And greater use of refrigeration as free energy will enable will likely greatly reduce waste anyway.
 * A simpler way of saying all that is that while it may be true we grow more then enough food to feed everyone, that doesn't mean growing more won't enable us to better feed everyone. In the real world, you can argue whether that's what we should be concentrating on but in this wonderworld, since you have free energy you can just grow more food and not worry about trying to prevent all that waste.
 * Of course there is also the question of what's valuable in a world of free energy. In theory, natural resources and land. But as some of the answers have illustrated, the importance of land is less clear when you can do silly things (although it still has importance). And even resources. People could mine them from asteroids, the sun etc. Or even make them themselves... In practice, using particle accelerators or nuclear reactions to generate particles you want is so outrageously expensive you'll never do it if you need quantities in bulk. But with free energy, you probably could.
 * In other words, I agree with SB here, this is a silly question we can't answer. The world would change drastically and presuming we survive the upheavel, what it would be like we can't say.
 * Nil Einne (talk) 07:47, 29 January 2010 (UTC)
 * We've pretty well covered the good things "unlimited free energy" could do. Going off past example (as per Mr.98, and human nature as per Tango) where such things are misused, I'm sure someone would use it to power weapons such as 'rail' guns (wear problems being solved) or huge Tera-Watt lasers, or find a way to use it in some other as yet unimagined way of killing/chopping/blowing us all up. Of course some defensive measures that are now limited by power availability become practical. (Shields up?) 220.101.28.25 (talk) 11:09, 29 January 2010 (UTC)
 * User 220.101.28.25 has rightly identified that the worst that humans can do with a powerful resource is what they will do, which is to hoard it and deny it to other humans. Such a scenario is explored in the novel Dune where the resource is a spice that confers cosmic powers and is simply the most essential commodity in the novel's fictional universe. People exploiting, and competing for, an unlimited energy source would probably lead to the same MADness as a nuclear confrontation and turn our fertile Earth into a ravaged desert. Cuddlyable3 (talk) 14:41, 29 January 2010 (UTC)
 * Yes, with unlimited free energy, we could transform the face of Arrakis! --Neptunerover (talk) 15:21, 29 January 2010 (UTC)
 * Save the Sandworm! Fremen against Terraforming --220.101.28.25 (talk) 20:16, 29 January 2010 (UTC)
 * People like the idea of a simple technological fix. But it never works out that way. There are always unintended consequences, and there are always resource allocation problems, and there is always politics sitting on top of that—basic human desires for power, sex, avarice. You will still have crazy religions, you will still have people who will organize for disorder, you will still have incompetence, you will still have idiocy, you will still have ridiculous tribal notions being expressed at a national (or planetary) scale. There are no utopias and can never be if you are considering them populated by actual human beings and not characters from Star Trek. Look around at the people around you, imagine them in your hypothetical world of the future, and imagine that they wouldn't bungle it up and create problems. The problems are more than technological in nature, and the solutions (if there are to be any) must be as well. And no solution is ever going to be final (thank goodness). --Mr.98 (talk) 15:11, 29 January 2010 (UTC)


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

Has anyone mentioned desalination yet? "Large-scale desalination typically uses extremely large amounts of energy". The deserts would be greened. World hunger would be reduced until the increased population rate brought it back again with much higher crowding. 78.146.98.144 (talk) 16:00, 30 January 2010 (UTC)
 * In order, Ariel, Trevor then me. Anyway I didn't answer this old discussion primarily to say that but to point out this is one of the many streams of evidence how much nonsense all the crap free-energy conspiracy theorists spout is. Free energy isn't something scientists are scared of. It's like one big wet dream. Even for selfish people (whether scientists or whoever) as several people pointed out it's clearly to their benefit to find some way to hoard all that free energy rather then think they can magically supress it. Edit: And wow don't you love it when you come across an article on a relatively obscure and not exactly frequenly changing topic for completely unrelated reasons and it's been updated with recent developments from about 2 days ago, Eugene Mallove Nil Einne (talk) 18:07, 3 April 2010 (UTC)

neutron up quark color
Neutrons consist of thee quarks, two 'down'-flavored and one 'up'-flavored. The three quarks have a color charge, one of red, green and blue; there is only one of each color. Does it matter (and can we tell) what color the up quark is? CS Miller (talk) 20:56, 28 January 2010 (UTC)
 * The color is a not a color like you would see. It's just a label, a name to distinguish one from the other. It has nothing to do with visible color, you could call them zee, vee, and shmoo and it wouldn't change anything. (But see Color confinement and quantum chromodynamics.) Ariel. (talk) 21:51, 28 January 2010 (UTC)


 * The colours switch readily between the quarks. The force carriers of the strong nuclear force "carry" colour and anti-colour charges around. So the up could have any of the three colours at any time. EverGreg (talk) 22:04, 28 January 2010 (UTC)
 * Thank you. I knew the a quark (of ~1pm diameter) color charge property has nothing to do with ~400nm photons, that's why I used the term 'color charge'. The color-charge article suggested that colors can spontaneously change with the emission and absorption of an appropriately bi-colored gluon, but didn't give an indication of how often this occurs. CS Miller (talk) 22:31, 28 January 2010 (UTC)


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


 * Everything in particle physics is like this. "Up" and "down" (the quark types) are really two directions in a different three-dimensional space, and other directions make sense also. The difference is that the symmetry of the up-down space is broken, and so the up and down directions are unambiguously defined. But the strong force doesn't break that symmetry, and the strong force dominates inside a neutron, so it's actually problematic to even say that a neutron contains one up and two down quarks. -- BenRG (talk) 23:17, 28 January 2010 (UTC)
 * Ah thank you. I was assuming that an up-green quark was a specific type of quark, and would remain as that type until it interacted with another quantum particle. BTW is there a good layman's introduction to quantum theory? I think I understood Hawking's A Brief History of Time (on the third attempt), so something around that level would be ideal. CS Miller (talk) 13:17, 30 January 2010 (UTC)

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

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


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

Bird identification
What kind of bird is this? It is in the Ozarks on Missouri in January. -- k a i n a w &trade; 23:42, 28 January 2010 (UTC)
 * That's a northern flicker. We have one that comes to our backyard feeder every so often and it's a beautiful bird.  Great that you got a photo of it.  Yours looks like a male, yellow shafted variety.  --- Medical geneticist (talk) 00:09, 29 January 2010 (UTC)


 * Thanks. I assumed that was the male.  It's partner wasn't nearly as colorful, which made me assume it was the female.  I also assumed the teeny little brown ones around them were the babies. --  k a i n a w &trade; 01:40, 29 January 2010 (UTC)