Wikipedia:Reference desk/Archives/Science/2011 August 31

= August 31 =

Superfluid
Is a superfluid a type of fluid or is it considered an entirely separate state of matter? Or is the difference decided by the definition of fluid that you subscribe to? Thanks. asyndeton  talk  01:30, 31 August 2011 (UTC)
 * Does Superfluid answer any of your questions? -- Jayron  32  01:39, 31 August 2011 (UTC)
 * Fluid is not a state of matter. It is a set of states that includes gases, liquids, plasma, anything that flows. Dauto (talk) 02:19, 31 August 2011 (UTC)
 * Of course, the entire concept of "state of matter" is still a somewhat arbitrary (if very useful) classification scheme. How various states of matter may be classified and delineated isn't written in stone, and different models will have different schema to organize various states.  -- Jayron  32  02:31, 31 August 2011 (UTC)

One small point Dauto. You missed out solids, which given certain scale/conditions can also be fluid.190.56.18.189 (talk) 12:30, 31 August 2011 (UTC)


 * Graphite is an example of a fluidic solid, if a shear stress is applied to the graphene sheets, they act as molecules in a liquid - they flow past one another, without seperating. This is why graphite is a lubricating agent. Plasmic Physics (talk) 12:59, 31 August 2011 (UTC)


 * Ice can also act as a fluid. Whoop whoop pull up Bitching Betty 20:45, 31 August 2011 (UTC)


 * No, glaciers are an example of a rheid, i.e. a solid that deforms and flows when a very large shear stress is applied. A proper fluid is a substance that continues to flows even as the applied force approaches zero.  Dragons flight (talk) 05:41, 1 September 2011 (UTC)

Different states of matter or different phases can be rigorously defined using the analytic properties of the free energy function. Two different thermodynamic states are in different phases if the analytic continuation of the free energy function in the neighborhood of one state to a neighborhood containing the other state does not yield the free energy function in that other state. Count Iblis (talk) 15:27, 31 August 2011 (UTC)
 * Translating into English what Count Iblis is saying: There are analytical ways to define (at least for most pure substances) differing states of matter by looking at the relationships between various components of the "free energy function", i.e. free energy, entropy, and enthalpy. Changes in state will result in changes of this relationship.  That is rigorously true.  But that doesn't work well in some types of matter which, like glass, which doesn't show clearly defined transitions from one state to another.  -- Jayron  32  19:55, 31 August 2011 (UTC)

Exactness of astronomy in 1602
In the Kunyu Wanguo Quantu of 1602, I found a table of some orbital periods which amazed me with its precision, before the use of the telescope: For moon, earth (or sun, in the heliocentric view) and mars, the values lie within ±0.001% of the modern values. The worst, Saturn, is still within 0.2%. (See table at zh:Wikipedia:詢問處). The 8th sphere, the "zodiacal heaven", is indicated as rotating with a period of 7000 years ("from west to east", just as all other spheres.) At first I thought that referred to the axial precession. But that was, according to our article, already known to be greater than 25000 years in Hipparchus' time. Was Matteo Ricci (or his sources) really that far off on that, or could he have meant something else? &mdash; Sebastian 08:14, 31 August 2011 (UTC)


 * I can't answer your main question, but yes, those sorts of measurements had been made extremely precisely by 1602, esp. by astronomers such as Tycho Brahe. His Uraniborg and Stjerneborg give a good idea of what the best astronomical instruments money could buy at that time. It was difficult and laborious observational work that required extremely good eyesight. I suspect (though I don't know this for a fact) that whatever measurements Ricci was using were derived from Brahe, whose work would have been well known, and well-regarded by Jesuits, by that point. (And despite their later backwards reputation, it probably should be recalled that the Catholic Church, and Jesuit order in particular, contained most of the best astronomers of the 16th and 17th centuries, and were certainly the largest patrons of astronomy at that time.) --Mr.98 (talk) 14:24, 31 August 2011 (UTC)


 * It's also the case that if one has even a single accurate observation from a very long time ago that can be accurately timed (say, an observation that a particular planet was in a given location during a particular solar eclipse), one can calculate the planet's orbital period to a very precise value (because effectively you have measured tens or hundreds of periods). {The poster formerly known as 87.81.230.195} 90.197.66.40 (talk) 16:50, 31 August 2011 (UTC)


 * Thank you for both your helpful and interesting replies, number guys! I too am impressed by the SJ's scientific patronage and scholarship. Just as an aside, it is fitting that they chose to translate "Catholicism" by 天主教 - "heaven-ruler-religion". Back to the subject of the forum; anyone has an idea what Brahe or the astronomers of his day could have meant by the 7000 year period? &mdash; Sebastian 18:28, 31 August 2011 (UTC)


 * According to Milankovitch cycles, "The combined effect of the two precessions leads to a 21,000-year period between the seasons and the orbit." There are four seasons and 21,000/4 = 7,000. However, that alone doesn't say much. ~ AH1 (discuss!) 19:45, 31 August 2011 (UTC)
 * Could be something else in Earth's cycles, unless of course this 7,000 is an arbitrary number. ~ AH1 (discuss!) 19:47, 31 August 2011 (UTC)

Chemistry XII Grade
Q1. Why is it so that all the Top elements in Group behave differently from its other family members in a periodic table? (OR) Why is it so that first element of each group shows different behaviour fro the rest of its group members? — Preceding unsigned comment added by 116.203.34.20 (talk) 10:38, 31 August 2011 (UTC)

Q1. Explain why is it so that first element of each group behave differently from its remaining members of the Group? — Preceding unsigned comment added by 116.203.34.20 (talk) 10:39, 31 August 2011 (UTC)

Q. What will be the structure of P2O5H2? — Preceding unsigned comment added by 116.203.34.20 (talk) 10:42, 31 August 2011 (UTC)


 * "If your question is homework, show that you have attempted an answer first, and we will try to help you past the stuck point. If you don't show an effort, you probably won't get help. The reference desk will not do your homework for you." Plasmic Physics (talk) 11:53, 31 August 2011 (UTC)


 * Wikipedia has an article about the Periodic table and it is also described in the Wikibook "General Chemistry". Cuddlyable3 (talk) 18:13, 31 August 2011 (UTC)


 * You can look in Phosphite for P2O5H22- as a Pyrophosphite ion, but if there is no charge, I don't know what this is. Graeme Bartlett (talk) 10:47, 1 September 2011 (UTC)


 * You really should come back with what you know and don't know as the policy says. But in the interest of general chaos I'll mention that surprisingly to me, our article on hypervalent bonding seems to downplay the familiar old explanation that d-orbitals from the lower periods are involved in that process... Wnt (talk) 23:10, 1 September 2011 (UTC)
 * It isn't d-orbitals from the lower periods, it is d-orbitals from the same period. Phosphorus's hypervalency comes from hybridization of the 3s, 3p, and 3d orbitals on the valence level of the element.  There are no lower d-orbitals; 3d is the smallest d orbital.  -- Jayron  32  02:37, 2 September 2011 (UTC)
 * You might want to discuss that at the article, which seems to take a different view. When I said "lower periods" I meant S or Se rather than O, P rather than N and so on - sorry for any confusion. Wnt (talk) 09:20, 2 September 2011 (UTC)

zebras
Are zebras considered a game animal and hunted for their meat in Africa (by humans, not lions)? Googlemeister (talk) 14:54, 31 August 2011 (UTC)


 * If only there were an encyclopedia around. Zebra.  -- LarryMac  | Talk  14:57, 31 August 2011 (UTC)
 * The rule of thumb is: If it's edible and legal (some times even if it's illegal) than someone in the world is eating it. Dauto (talk) 15:05, 31 August 2011 (UTC)


 * If your here in the UK you can easily try some. - I think subjects about food should be banned from this Ref Desk as it encourages my to raid  the fridge each time --Aspro (talk) 15:26, 31 August 2011 (UTC)
 * Regardless of any ethical issues, I don't think I could bring myself to buy anything from a site with such poor spelling: "biting of a mans arm"; "like Horse meat its sweater than Beef". *Shudder* AndrewWTaylor (talk) 17:02, 31 August 2011 (UTC)
 * What ethical issue? Dauto (talk) 18:51, 31 August 2011 (UTC)


 * Ethics aren't black and white. Googlemeister (talk) 19:22, 31 August 2011 (UTC)
 * Also, that comment smacks of discrimination against dyslexics.--Aspro (talk) 19:26, 31 August 2011 (UTC)
 * AndrewWTaylor does society a service by setting a standard that preserves the beauty of our precious English language and encourages the less literate among us to improve themselves. Cuddlyable3 (talk) 12:31, 1 September 2011 (UTC)
 * Dyslexia is a genetic attribute that confers talents that non-dyslexic people often  lack (look up some of the more modern research into this). Do you expect the colour blind to learn how to see colours? Would you advocate plastic surgery for all those that don't meet your notions of beauty? All that comment does is show  prejudice born out of ignorance. Indeed, society looses much talent when dyslexics get excluded from the education system.  Hardly the sort of service that an any enlightened society should be proud of -don't ya think?. --Aspro (talk) 13:51, 1 September 2011 (UTC) --Aspro (talk) 13:51, 1 September 2011 (UTC)
 * I don't see the reference to dislexia in the statement, would anyone care to point it out? Plasmic Physics (talk) 22:17, 1 September 2011 (UTC)
 * A Person with dyslexia who publishes a web site is just as capable of hiring a proofreader as anyone else. thx1138 (talk) 16:42, 2 September 2011 (UTC)
 * Why should they? Is not the meaning of what is written is clear? It is obviously a small company with limited resources, that no doubt wants to put the most effort where it  is most needed. Would your rather they skimp on hygiene  or something  else instead?  Yes, perhaps they could have employed a proof reader - but then again – why don't some large  organisations (say Fox News) bother to employ someone  to check their facts before they broadcast them! Fox News uses correct spelling  but do you trust them more because of that? These comments  smack of I'm OK, You're Not OK--Aspro (talk) 22:46, 3 September 2011 (UTC)
 * Wikipedia has an article about Theories of dyslexia none of which hint at it being a "genetic attribute that confers talents". Aspro may be confusing dyslexia with Autism. Please don't rant about spelling unless you can take the trouble to spell "society loses much" properly. The result of that negligence by Aspro was Aspro's failure to post what Aspro wanted to say, because Aspro's malapropism "society looses" actually means something different. Cuddlyable3 (talk) 15:07, 4 September 2011 (UTC)
 * Gosh. Talk about keep digging when your find your self in a hole. You seem more interested in having the last word before the topic rolls of the page. If you want to use WP for your argument from authority then  so will I – or rather I have now . I'll leave just two links for anyone left wondering., --Aspro (talk) 21:01, 4 September 2011 (UTC)

Also consider Lady Meux who rode around London in a carriage hauled by a pair of zebra. Ok, maybe not relavent but quite interesting anyway. Alansplodge (talk) 00:36, 1 September 2011 (UTC)
 * There's mention of an extinct zebra subspecies. I wonder if anyone has discussed the possibility of cloning? ←Baseball Bugs What's up, Doc? carrots→ 12:38, 1 September 2011 (UTC)
 * The Quagga article mentions that they got the DNA for that in 1984, but the technology to do anything with it is not there yet for cloning it. Googlemeister (talk) 13:19, 1 September 2011 (UTC)
 * So at least it's on the table. I recall similar discussions about the wooly mammoth. I don't know if anything every came of that. ←Baseball Bugs What's up, Doc? carrots→ 14:11, 1 September 2011 (UTC)
 * Restoring a species that way is almost certainly possible but very certainly difficult. It's one thing to take an intact living nucleus and slip it into an egg cell and after 174 attempts you get a live sheep.  It's another thing altogether to take scraps of DNA ten thousand base pairs long, splice them together perfectly into a fully known genome sequence without any errors or gaps anywhere (which still hasn't really been done even with humans AFAIK), then package that properly into authentic chromatin with histones and centromeres and telomeres and proper origins of replication and DNA methylation to suppress all the endogenous retroviruses from getting rambunctious, and who knows how many other special structures.  I mean, it's a project that can and should be done, which even might become routine, but it's a moon shot, something that takes a lot of people working together perfectly doing things that have never been done before.
 * In practice, I suspect that a bastardized approach might be more likely to prevail in the foreseeable future - namely, identifying the crucial genetic differences that made a wooly mammoth or a quagga look distinctive, and splicing them in gene by gene until you have something that plausibly simulates those animals. But that's just a cosmetic operation and it shouldn't be confused with a genuine resurrection of the species.  Still, doing that depends on the quality of palentological samples available (to see which genes were under positive selection or correlated with visible changes in the species' appearance), and the overall level of knowledge about what various genes (or their orthologues) do in related species.  I'm not sure it will be that much easier. Wnt (talk) 23:01, 1 September 2011 (UTC)

potatoes, catalase, hydrogen peroxide...and an oven!
I had to do the ol' potato homogenate + hydrogen peroxide experiment in order to determine the rate of activity of catalase. My variable was heating the homogenate in an oven that was set to 80° C. Unfortunately, I didn't have a thermometer, so I left it in there for what seemed a good long time (about 15 or 20 minutes) for it to reach that temperature.

I don't know how standard this experiment is, but I had specimen tubes, sealed with rubber bungs, with thin tubes inside the bungs. When inverted the reaction causes liquid to drip from the narrow tubes.

I did four replicates with the heated potato and during any counting downtime I had the homogenate back in the oven to keep warm. The counts for my first replicate was in the teens. For each following replicate the mean count declined, until by the last replicate there were no drips, for 3 minutes out of 4.

My question is: what is responsible for the reaction declining so much, over a period of only 20 minutes, with all other conditions the same?

I have two ideas: Was the homogenate not at 80° for the first replicate? Was it at a lower temperature that still allowed catalytic function, and then reach or get closer to 80° while it was waiting in the oven for the other replicates to finish? And obviously, the hotter it got, the less it worked on the hydrogen peroxide.

My other idea is that the homogenate was at 80° for all of the replicates, but that the loss of enzyme function was progressive the longer it was heated. Would this have been because more enzyme succumbed to the effect of temperature (enzyme quantity) or because the enzyme molecules themselves progressively broke down, having slowed down first (enzyme quality)?

What do you think? 82.71.20.194 (talk) 17:47, 31 August 2011 (UTC)
 * Probably the first; enzymes are very peculiar things, and even a small change in their structure can lead to a complete cessation of function. In otherwords, an individual enzyme molecule doesn't progress from "working real well" to "sorta working" to "not working at all", there is no quality continuum.  The individual molecule gets broken, and just stops working, in most cases.  So, I would guess that the decrease in activity would be due almost entirely to having a lower and lower concentration of working molecules.  -- Jayron  32  19:50, 31 August 2011 (UTC)
 * Okay, that seems to make a lot of sense. Do you think that the homogenate was at 80° for each replicate, and that more enzymes succumbed to that heat the longer it was heated, or do you think that perhaps the temperature of the homogenate was still increasing as the experiment progressed through the replicates?  I'd like to think that I got the basic thing right of heating my homogenate to 80° and pretty much keeping it there, but I have to admit it almost means that some of the catalase molecules had to be 'tougher' than others in order to have kept their structure for longer at the same temperature.  Of course, it's not a case of reaching a certain low-ish temperature and bang, all the catalase collapses, so there would have to be some degree of progression...but I don't know how much.  Hmmmm.  82.71.20.194 (talk) 20:10, 31 August 2011 (UTC)
 * It's tough to say. On the one hand, decomposition reactions probably have relatively simple first order kinetics, and are likely nearly instantaneous; i.e. when the molecule gets to a certain temperature, bonds break and the molecule denatures almost instantaneously.  OTOH, if you are dealing with a potato in an oven which is right at the denaturation temperature, a potato is a pretty lousy conductor of heat, so you will probably have a temperature gradient, and it may take a long time for the catalase near the center of the potato to deactivate; which is why you see the time dependence in your experiment; i.e. even if it is 80 degrees on the outside of the potato, it takes some considerable time for the middle to get to 80.  So, your idea that the initial potato mash (I assume that's what you mean by homogenate) wasn't all at 80 degrees, and the longer oven times only caused the heat to more evenly distribute.  A possible way to test this would be to try two parallel experiments: one with the potato homogenate in a beaker, and one with the same amount spread out in a very thin layer, say on a petri dish.  If the one in the beaker "lasts" longer, you know it is probably the heating time which having an effect, since the sample in the petri dish, with a larger surface area and being more "spread out" should reach the equilibrium temperature faster.  -- Jayron  32  01:16, 1 September 2011 (UTC)
 * I'm not very clear on how you did the experiment - I assume you added the hydrogen peroxide after the period of heating so that it wasn't depleted before you measured the drips? In which case you should be able to measure denaturation as it happens (I assume that "homogenate" means you're not talking about lumps of potato and heating was fairly rapid and uniform).  From a lab writeup like  I assume the potato catalase denatures at some fairly low temperature like you'd expect, so this seems quite plausible. Wnt (talk) 22:49, 1 September 2011 (UTC)

Name of the selenium analogue of greigite
How is the selenium analogue of greigite called? How are its the magnetic properties compared to greigite and magnetit?--79.119.214.150 (talk) 20:14, 31 August 2011 (UTC)
 * May be Ferroselite is what you're looking for? Dauto (talk) 20:42, 31 August 2011 (UTC)


 * If so, it is said to become magnetic when heated, while the monoselenide (FeSe) is ferromagnetic. Mikenorton (talk) 20:54, 31 August 2011 (UTC)


 * According to Fe3Se4 is ferromagnetic below 314K.  According to  there is a broad "FeSe" composition that doesn't adhere very precisely to stoichiometry, which perhaps explains why I didn't immediately come up with a different name for it than other somewhat different Fe/Se ratios.  But this is not my field, just the outcome of a real quick search to try to goad the people who know into explaining this to us. ;) Wnt (talk) 09:16, 2 September 2011 (UTC)

Artificial gonads
Is it possible to create an artificial gonad in vitro using tissue engineering? Whoop whoop pull up Bitching Betty 21:01, 31 August 2011 (UTC)


 * Possible "now" or possible "in principle"? I don't really have a very good reason for my answers but I'd say no and yes respectively. Vespine (talk) 22:09, 31 August 2011 (UTC)


 * How come? Whoop whoop pull up Bitching Betty 23:00, 31 August 2011 (UTC)


 * Come on, throw us a bone, how come what? Vespine (talk) 00:06, 1 September 2011 (UTC)


 * Actually, come to think of it, I think my answer is for male gonads, I think female gonads would present extra challenges which might possibly preclude the possibility of engineering functional female gonads... Testicles are just sperm factories, if we've ALREADY engineered functional livers and pancreases I can't see why testicles couldn't eventually be engineered. But sorry, these ARE just guesses, I hope someone who actually KNOWS something about this subject can chime in. Vespine (talk) 00:14, 1 September 2011 (UTC)


 * You would need human tissue to start with. You'd need male tissue for testicles, since only men have Y chromosomes.  You'd probably want female tissue for ovaries, as only females have two X chromosomes, but you could theoretically use male tissue, as men do have a single X chromosome (and mitochondrial DNA, which is normally only passed on from the mother).  Now for the hard part, you need to find some way to convince whatever stem cells you got from the man or woman to start building the appropriate gonads.  I imagine the proper supply of certain hormones is part of it, but there must be more to it than just this.  And, of course, you also need to supply a suitable environment for those cells to develop and reproduce.  So, theoretically, yes, but now, heck no.


 * Note that just removing a testicle of ovary from somebody (say a person who just died) and convincing it to continue to do what it does, would be considerably simpler. StuRat (talk) 03:13, 1 September 2011 (UTC)
 * The eggs are stored in the ovaries, if I recall correctly. That would put the recipient in the position of possibly becoming a surrogate to a long-dead biological mother. ←Baseball Bugs What's up, Doc? carrots→ 07:51, 1 September 2011 (UTC)
 * And neither testicles nor ovaries are simply gamete factories. Both produce important sex hormones (testicles produce testosterone + other androgens and ovaries produce estrogens and progesterone, plus possibly other hormones too.)  And for either one you would also need to coax the cells into undergoing meiosis, which I think would probably be the tricky part (though as I have no real background in tissue engineering I have absolutely no idea whether any of my assumptions are in any way correct.) Whoop whoop pull up Bitching Betty 20:23, 1 September 2011 (UTC)

Really big mosquito. Species?
I have make some photos of the really big mosquito - approximately 4 cm (1.5 in) in wing-spread. This monster live in Baden-Württemberg, Germany.

Could you please provide some piece of biological classification for this thing? (sorry for my english) - Ewigekrieg (talk) 21:02, 31 August 2011 (UTC)


 * A crane fly by the look of it, what we in the UK call a daddy longlegs - not a biting fly. Mikenorton (talk) 21:08, 31 August 2011 (UTC)


 * Yes, it isn't a mosquito, it is a crane fly. As for which of the 4200 or so known species, I'll leave this for someone else to say... AndyTheGrump (talk) 21:10, 31 August 2011 (UTC)


 * How did they figure out 4,200 species? They all look about alike. ←Baseball Bugs What's up, Doc? carrots→ 07:49, 1 September 2011 (UTC)
 * "about" is not good enough if you're a geek. Imagine all your baseball stats being "about". Richard Avery (talk) 14:11, 1 September 2011 (UTC)


 * They may be difficult to tell apart with the naked eye, but if you have access to a compact digital camera, I'd recommend taking a close-up - most such cameras can focus to within a few inches (a side-effect of the need for compactness) so you can get a decent macrophotograph without too much difficulty, and see some interesting details - using the flash often works best. The OP's photos are a little out of focus, but even so you can see the crane fly's halteres, which function as vibrating structure gyroscopes, and just about make out some of the details of its complex mouth parts. As always, Wikipedia commons obliges with a perfect image (taken with more expensive equipment - you won't get this close with a standard compact digital): AndyTheGrump (talk) 15:40, 1 September 2011 (UTC)


 * Thanks! I change the description of photos. - Ewigekrieg (talk) 11:27, 4 September 2011 (UTC)

Citrobacter Nuclear Reactor
Would it be possible to grow Citrobacter on natural media to enrich the concentration of uranium and then use them as fuel for a moderated (RBMK or CANDU) nuclear reactor? Whoop whoop pull up Bitching Betty 21:14, 31 August 2011 (UTC)


 * Only if the bacteria can differentiate between U-235 or U-238, which I find unlikely (keep in mind the isotopes are chemically identical). (Note that you wouldn't need to use the bacteria as fuel, and probably couldn't, since it wouldn't likely have the uranium in a chemically useful form — e.g. as an oxide or metal. If you could get something like that to absorb U-235, though, it would be rather basic chemistry to strip the uranium from the bacteria and convert it into metal or oxide or whatever you wanted it to be. The hard work is separating U-235 from U-238, not U from other stuff.) A more realistic (in the next 50 years or so) possibility along similar lines that I have read about is to use nanobots of some sort to do that sort of enriching (exact details not available, but presumably you could make them do very specific physical work to separate them out). The only way such an approach is an advantage to such an approach over current methods is if it is easier (technologically, politically) to make nanobots than it is to make reactors or centrifuges or laser enrichment or whatever, which isn't currently the case, but might be in a few decades. --Mr.98 (talk) 21:50, 31 August 2011 (UTC)


 * RBMKs and CANDUs don't need enrichment. They can run on natural uranium; check the relevant articles.  And Citrobacter could make very-low-grade uranium deposits (less than 1/10 percent uranium) commercially viable. Whoop whoop pull up Bitching Betty 22:05, 31 August 2011 (UTC)
 * Since you already seem convinced of the answer to your question, do you mind if I ask why you asked it? APL (talk) 02:20, 1 September 2011 (UTC)
 * Oh, I see what you are getting at. (Note that when you use phrases like "enrich the concentration of uranium," it sounds like you are talking about uranium enrichment unless you clarify.) I'm not sure what the advantage would be over just leaching out the uranium from the ore chemically. The problem with low quality ores is that you just need a lot of processing, an uneconomical amount. I find it unlikely that bacteria are going to change that — you'll still need to harvest the ore and the bacteria from the ore. That's got to be around the same level of effort as the normal mining/refining process. --Mr.98 (talk) 11:56, 1 September 2011 (UTC)


 * Why bother? In cost per kilowatt-hour, enriched uranium is already significantly cheaper than coal, oil, or gas.  Fuel costs really aren't a limiting factor in the adoption of nuclear power, rather the costs are tied up with building and operating safe reactor facilities.  Dragons flight (talk) 03:00, 1 September 2011 (UTC)
 * And with disposing of the spent fuel rods, etc. ←Baseball Bugs What's up, Doc? carrots→ 07:48, 1 September 2011 (UTC)
 * That's at the current level of demand. If there were to be an expansion of the use of nuclear power to the point that it could largely replace carbon-based fuels, demand would go way up.  Could we fill it at the current, or any, cost?
 * I think it's worth thinking about. I know such an expansion is currently politically impossible because of the events in Japan.  But the pressures that make it plausible aren't going to go away. --Trovatore (talk) 03:07, 1 September 2011 (UTC)


 * There is a practically infinite amount of uranium dissolved in sea water (more than humans would ever use, even if we replaced all power generation with nuclear). Extracting uranium from sea water is much more expensive than mining using current technology, but it isn't crazy expensive.  If we had to get our uranium from sea water it would raise the cost of electricity 3-4 cents / kWh.  That's a large enough increment that people would notice, but not so large as to be uneconomical.  Full conversion to nuclear production is entirely possible with existing technology, but as you say, the political environment makes it an implausible option.  Dragons flight (talk) 13:42, 1 September 2011 (UTC)


 * Two things: 1. breeders make this a lot easier, if you ignore the political problems; 2. low quality ores are only uneconomical because of current market conditions. If the demand went up, the price would go up, and they'd become economical again. I still don't see why bacteria are going to be helpful though. We have perfectly good methods of using low quality ores; the problem is that mining them is just expensive for what you get out of it. I don't see how the bacteria are supposed to change that (are you going to pump them in and pump them out again? I mean, how are you actually going to get the bacteria to the ore, and then get the bacteria out of the ore?). --Mr.98 (talk) 11:56, 1 September 2011 (UTC)
 * Increasing nuclear energy production means an increase in radioactive waste. Where should it be stored? ←Baseball Bugs What's up, Doc? carrots→ 14:10, 1 September 2011 (UTC)
 * New Jersey? Googlemeister (talk) 15:34, 1 September 2011 (UTC)
 * With breeder reactors you get a lot less of the long living radioactive waste. The remaining waste should be concentrated and be used as heat sources. The total volume then isn't large and because it is used it shouldn't be considered to be "waste" anymore. Count Iblis (talk) 15:45, 1 September 2011 (UTC)


 * The waste storage issue is a more of a political problem than a technical one. There are lots of pretty reasonable and rational solutions to the relatively limited spent fuel problem (the total volume of waste is pretty small compared to other types of hazardous waste). But that's a different question than the one being discussed here, I think. --Mr.98 (talk) 22:45, 1 September 2011 (UTC)


 * Sorry if this this comes across as selfish, but as long as it's not within my lungs anywhere is fine.  — Preceding unsigned comment added by Anonymous.translator (talk • contribs) 00:36, 2 September 2011 (UTC)
 * The problem is that politically in the US, the government wants to impose rules on nuclear waste storage so that the radiation has to be guarenteed to be below a set level for 1,000,000 years. Unfortunately, that kind of standard is completely unrealistic since our predictive methods for that kind of a time span is so incredibly vague.  Googlemeister (talk) 13:22, 2 September 2011 (UTC)
 * I was trying to point out how unfair it is to harshly regularly certain types of radioactive wastes (to unachievable levels even) while imposing no restrictions on other types of radioactive wastes. Radioactive wastes resulting from fossil fuel burning has killed far more people than Chernobyl and yet it is still not regulated.Anonymous.translator (talk) 19:41, 2 September 2011 (UTC)

Coordinates
Can a person tell how close (feet wise or milage wise) certain coordinates are from each other; example, how far apart physically are Sueca from Cullera from Alzira?--Doug Coldwell talk 21:54, 31 August 2011 (UTC)
 * Yes; but calculating the shortest distance between two spherical coordinates is actually a little complicated; our article great circle derives the math for you. The entire science of geodesy formalizes this problem and deals with the practical details.  You might also read about "the standard Geodetic Problem".  (It's sort of a fancy, old-fashioned way of asking how far apart two cities are).  Nimur (talk) 22:27, 31 August 2011 (UTC)
 * Another link: Vincenty's method, one of many "practical implementations" of the formula to calculate distance between cities. To be honest, nobody does this stuff nowadays - it's a little difficult and esoteric - ... most people just use a GIS software tool.  The only people who really still do geodetic calculations are ... designers of GIS software tools.  Nimur (talk) 22:55, 31 August 2011 (UTC)
 * Unless you want extraordinary precision, you can just use the scale on Google Maps. It appears to me that Alzira is about 11 km from Sueca and 15 km from Cullera and that Sueca and Cullera are about 6 km apart (all as the crow flies). Deor (talk) 23:12, 31 August 2011 (UTC)
 * Thanks Deor.--Doug Coldwell talk 11:10, 1 September 2011 (UTC)

Underice explosion
What would happen if an explosive was detonated under the ice on a frozen lake? Whoop whoop pull up Bitching Betty 23:02, 31 August 2011 (UTC)


 * That dependends on the amount of explosive used, the thickness of the ice layer, and the depth underneath the ice layer. Plasmic Physics (talk) 23:52, 31 August 2011 (UTC)


 * I meant assuming an average ice thickness (around 6 inches?), an average-sized lake, and an explosive about the size of a few sticks of dynamite, detonated about ten to fifteen feet below the ice. Whoop whoop pull up Bitching Betty 23:56, 31 August 2011 (UTC)


 * A pressure wave would deform the ice in an upward direction. It either would or would not break the ice. Probably. --Tagishsimon (talk) 00:03, 1 September 2011 (UTC)


 * As an aside, you'd prob'ly be better off using torpex instead of dynamite -- torpex is waterproof, while dynamite ain't. 67.169.177.176 (talk) 05:39, 1 September 2011 (UTC)


 * I said about the size of two sticks of dynamite, not to actually use two sticks of dynamite (ouch.) Whoop whoop pull up Bitching Betty 20:26, 1 September 2011 (UTC)


 * On a much larger scale, subglacial volcanoes exist. ~ AH1 (discuss!) 23:53, 2 September 2011 (UTC)

Energy Efficiency Calculations for Waste Heat Used in a Combined Heat and Power System
Inquiry: In determining the energy efficiency under Internal Revenue Code section 48(c)(3)(A)(iii), how is this done if the system is comprised solely of waste heat. Is it 100% efficient?

Facts: An existing industrial facility is currently venting its waste heat into the atmosphere. In a review of its efficiency standards, it has been proposed that the waste heat could be considerate to run both a turbine and other thermal applications without applying any additional fuel. As a part of the payback for this project is the investment tax credit for combined heat and power under section 48. The facility achieves both the 20% electrical and thermal standards, but we are unclear as to the calculation of efficiency when no additional fuel Cogenerationis involved. Kgordon016 (talk) 23:26, 31 August 2011 (UTC)
 * Welcome to . Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our policy here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know.-- Jayron  32  01:06, 1 September 2011 (UTC)
 * Welcome to . Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our policy here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know.-- Jayron  32  01:06, 1 September 2011 (UTC)

You misunderstood. The question based on the unclear statute as written by the EPA and comment by the DOE. No one in either organization has been able to address it either. I believe that someone in school could handle this, they would have a job. — Preceding unsigned comment added by Kgordon016 (talk • contribs) 00:49, 2 September 2011 (UTC)


 * Try searching through the Reference desk archives. ~ AH1 (discuss!) 23:51, 2 September 2011 (UTC)


 * I'm confused about this. Are you saying your government offers some tax credit, but no one in the government knows how to calculate whether you qualify for said tax credit? Nil Einne (talk) 19:25, 3 September 2011 (UTC)

3066 McFadden
I was doing some vandalism removal, when I found this article. Being a huge Star Trek nerd, I was wondering if there was any relation of 3066 McFadden to Gates McFadden. Bluefist  talk 23:34, 31 August 2011 (UTC)


 * As our McFadden (surname) article indicates, this is a common Scottish surname, so there is no particular reason to think that it would be, and given that it was apparently discovered (and presumably named) in 1984, whereas Gates McFadden didn't appear in Star Trek until 1987, I can think you can safely rule this out. AndyTheGrump (talk) 01:31, 1 September 2011 (UTC)


 * According to NASA, it's named for this woman. Deor (talk) 01:45, 1 September 2011 (UTC)
 * And I've just discovered that we have a series of lists explaining the eponyms of asteroids. This question, for example, could have been answered by looking at Meanings of minor planet names: 3001–3500. Apparently, there are several Star Trek–related asteroid names, including 4659 Roddenberry, 9777 Enterprise, 68410 Nichols, and, indirectly, 2309 Mr. Spock. Deor (talk) 14:25, 1 September 2011 (UTC)