Wikipedia:Reference desk/Archives/Science/2012 July 21

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July 21

Is is possible to be a sociopath in a narrow area?

we don't offer medical diagnoses, including psychaiatric
The following discussion has been closed. Please do not modify it.
I am certainly not a sociopath in any classical sense, indeed if anything I am fairly sure for various reasons that I have considerably more empathy than most people. However, what I just can't do is get offended by anything. I intellectually understand what offends other people (learned, I think, from trial and error) but have no visceral response at all. What's up with that? Egg Centric 00:41, 21 July 2012 (UTC) Addition: Sometimes I pretend to be offended just cause I have the sense I should be claiming to be, even though I'm not, and I still can't help but think that that is what everyone else is doing. Also sometimes I get angry with twats and express it as being offended, but only cause that seems to be socially acceptable thing to do, not cause I'm actually offended. Egg Centric 00:47, 21 July 2012 (UTC) Can't you get offended by anything, asshole? So, I can crack up a joke about your mommy (that whore) and you would laugh with me? 88.9.110.244 (talk) 00:54, 21 July 2012 (UTC) If it was funny Egg Centric 01:28, 21 July 2012 (UTC) Nah, you're probably just INFP. Some day, someone will cross a line that you didn't know was there, and you'll be surprised by your own reaction. --Amble (talk) 00:59, 21 July 2012 (UTC) Apart possibly from introversion, where I am probably an introvert in terms of intrinsic preference (in that I loves me some nerd time) but an extrovert by usual behaviour, I am basically the opposite on that scale, so I doubt it Egg Centric 01:35, 21 July 2012 (UTC) Interesting. Shows what you get for taking things like MBTI too seriously (bad guesses). --Amble (talk) 01:55, 21 July 2012 (UTC) Three unrelated points: A) As far as psychologists are concerned, there is only "sociopath" and "not a sociopath". While indeed you can fit some of the criteria and not others, there is no defined thing as "sociopath for some things but not others". B) That said, I have only known one other person who so adamantly insisted they never could not be offended. I later realized this insistence was a coping mechanism and they actually took offense quite easily, but hid it well; C) Are you sure that nothing offends you, or are you just talking about insults? Being able to be unbothered by someone's attempts to get a rise out of you makes you more enlightened than the average human being, in my opinion. What if it is something more extreme, like being formally and publicly accused of a wrongdoing you are not guilty of? Or something really extreme, like watching someone kill a baby? Truth be told, even if you could honestly say "not offended" to all of those, I would scream that you're a sociopath. Though if you want a formal diagnosis, you'll need to see a psychologist. Someguy1221 (talk) 01:00, 21 July 2012 (UTC) It may be that we are using different definitions of offended. Of course I would not want to watch someone kill, or even torment a baby. There would certainly be a visceral response. But I couldn't characterise that response as offence, it would be more like horror. I am not unable to be insulted either in principle, but it would just make me angry or irritated. I am talking more about say sexism, racism, or whatever. Egg Centric 01:28, 21 July 2012 (UTC) Still wouldn't call you a sociopath. You just sound like you subscribe to "don't give a fuck"ism, whether you know it or not. Someguy1221 (talk) 01:34, 21 July 2012 (UTC) You are not a sociopath. Sociopaths are narcissists, you are not. Check here: Sociopaths#Cleckley_checklist. Maybe you have reached enlightenment. 88.9.110.244 (talk) 01:52, 21 July 2012 (UTC) We should not be offering diagnoses of people's psyches. μηδείς (talk) 02:46, 21 July 2012 (UTC)

Effect of Electric or magnetic fields on crystallization

So I was thinking if we have a compound whose molecules have polar covalent bonds (imagine it's a simple one, a diatomic molecule) well,the favorable position for them when the compound is crystallized must be something like:

+ - + - + - + - + -

- + - + - + - + - +

But in the presence of an electric field, the favorable position is:

+ + + + + + + + + +

- - - - - - - - - -

(assuming the field is upward) This made me wonder does presence of electric fields or magnetic fields make the crystallization harder (like in this case, although I'm not sure because although the arrangement is unfavorable for crystallization, at least they're aligned in the same... strike?) or easier? Is it done? How effective/practical is it? Does it have any use? What, if so? — Preceding unsigned comment added by Irrational number (talk • contribs) 04:59, 21 July 2012 (UTC)

In an arbitrarily strong electric field, if you manage to get the second structure you show, the crystal has ceased to be a crystal. Although at the necessary field strength you'll also be stripping electrons off the atoms. Anyway, this does actually have applications in the "inverse piezoelectric effect". Basically, by applying an electric field to a crystal, you can cause a physical distortion in the crystal. This effect has been used variously to make buzzers, very-fine-tuned motion control systems, and experimentally in noise-cancellation systems. To find out more you'd best search on Google, as Wikipedia has precious little information on it. Someguy1221 (talk) 06:56, 21 July 2012 (UTC)

Actually, what I meant was that if the compound is initially in liquid phase, how is the kinetics and/or thermodynamics of crystallization affected by the field? could it crystallize at a lower/higher temperature? what about dipoles/ionic compounds in solutions? how are they affected, do they start crystallizing at different concentrations?(I think it will be less effective for ionic compounds I guess, since the separation of charges will be harder of course, but anyway)--Irrational number (talk) 08:13, 21 July 2012 (UTC)

...anyone?--Irrational number (talk) 23:41, 22 July 2012 (UTC)

How is this (the Poincaré recurrence theorem) consistent with the second law of thermodynamics?

Widener (talk) 08:37, 21 July 2012 (UTC)

How is it inconsistent with it? Poincaré recurrence theorem is related to Ergodic hypothesis which basically states that all possible states are equally probable (a priori), while the second law (within statistical mechanics framework) states that the number of available states increases with entropy, making the higher entropy a more likely outcome. Dauto (talk) 13:53, 21 July 2012 (UTC)

I do not know your example, but the second law a little outdated and has problems.thanks water nosfim . — Preceding unsigned comment added by 81.218.91.170 (talk) 13:57, 21 July 2012 (UTC)

The 2nd law presents some difficulties of interpretation, but that's our problem, not the law's problem. The law itself is considered correct (no problems) and up to date (not outdated). Dauto (talk) 14:05, 21 July 2012 (UTC)

Considered to some people, depending on your points of view,And how you doing statistics , thanks water — Preceding unsigned comment added by 81.218.91.170 (talk) 14:26, 21 July 2012 (UTC)

Here are some articles related to that question: H-theorem, Loschmidt's paradox, Fluctuation theorem, Arrow of time. Dauto (talk) 14:02, 21 July 2012 (UTC)

The Poincaré theorem applies to a system in equilibrium. The second law only makes meaningful statements about systems that are not in equilibrium. Looie496 (talk) 15:46, 21 July 2012 (UTC)

There is only a contradiction within classical thermodynamics where you take the second law as a basic postulate. As Dauto points out, there is no problem with statistical mechanics as the second law is formulated in a probabilistic way there. It can be shown that large fluctuation to lower entropy states are most likely going to happen via a sequence of small steps which under time reversal is just how the system would relax back to the higher entropy state starting from the lower entropy state, see this article. Here they give an example of how a piano will most likely re-appear out of thin air. Count Iblis (talk) 16:22, 21 July 2012 (UTC)

Interesting paper, thanks for the link, Count Iblis. A nitpick: the authors assume that "a series of consecutive statistically unlikely events, rather than one instantaneous very unlikely event" is more probable. But, this depends on the specifics of each event - it is not a generally true statement. For any specific case, we'd have to specify what the events are, and calculate their probabilities, in order to determine which case is more unlikely. Nimur (talk) 17:13, 21 July 2012 (UTC)

Thank you for your responses. In particular, I was interested to know how the Poincaré recurrence theorem was consistent with the heat death of the universe (a consequence of the second law of thermodynamics). Widener (talk) 18:18, 21 July 2012 (UTC)

Homo Erectus (et al) Extinction?

What are the theories as to the disappearance of stable populations of tool using, fire making hominids like H. Erectus, ergaster, etc. And why doesn't it mention those theories on the wikipedia article for them? I'm not sure I buy that H. Sapiens showed up and were just so awesome that they hunted down and out-competed every last pocket of them from the entire planet. Surely there are more cogent theories than that. --68.190.114.51 (talk) 09:36, 21 July 2012 (UTC)

For H. ergaster see Homo ergaster#Origin and extinction. Otherwise Neanderthal extinction hypotheses#Interbreeding. These species may also have simply evolved over time into other forms of Homo (before H. sapiens existed). See also human evolution and Human evolutionary genetics. And possibly Archaic human admixture with modern Homo sapiens
• If there are any other encyclopaedic theories, with reliable sources, you (68.190.114.51) are free to add them.
So possibly Interbreeding. They genetically became part of ... us, Homo sapiens (Wikipedia editorailis) (man who edits Wikipidia) ;-). - 220 of ^Borg 10:23, 21 July 2012 (UTC)

Specific to H. Neanderthal, climate change may have been a factor: "Climate Change Killed Neandertals, Study Says," National Geographic News, or maybe it was Volcanism? "Volcanoes Killed Off Neanderthals, Study Suggests", again, National Geographic . - 220 of ^Borg 10:34, 21 July 2012 (UTC)

One species only has to be ever so slightly better suited to it's environment than another to replace it. Consider the introduction of various placental mammals to Australia, which threatened to wipe out the native marsupials, with only massive culling by humans able to prevent this from happening. StuRat (talk) 22:49, 21 July 2012 (UTC)

In that case Extinction particularly Species#Causes may make enlightening reading. Unfortunately it only makes passing mention of extinction relating to Homo, and then relating only to Homo sapiens. One interesting point made is "A typical species becomes extinct within 10 million years of its first appearance ..." according to A Mathematical Model for Mass Extinction.Cornell University.- 220 of ^Borg 07:17, 22 July 2012 (UTC)

Does this physicist literally want to go back in time to save his dad?

I vaguely remember hearing Ronald Mallett talk to NPR talk show host Terry Gross about what first got him interested in time travel (the death of his father) and from what I remember, despite his intelligence, I got the impression that he actually still harbored the idea of going back in time, finding his dad, and saving him. From our article: "In 2006 Mallett declared that time travel into the past would be possible within the 21st century and possibly within less than a decade."

Can anyone confirm if it's the case that this man literally thinks he will one day engage in some fantastical journey through time to save his dad? Peter Michner (talk) 14:06, 21 July 2012 (UTC)

I seem to recall that at the end of the interview/story that Mallett concluded that he wouldn't be able to go back to any time prior to the building of the machine? But my understanding was yes, he was invested in the idea of creating a literal time machine. --Mr.98 (talk) 16:12, 21 July 2012 (UTC)

I heard an interview with the same person (I don't recall the name, but I'm fairly certain it was the same guy) on a certain radio show some time ago. I do recall him stating that the death of his father was what motivated him to research time travel. He also pointed out, though, that (by some complicated physicist reasoning that I don't particularly recall) he believes only time travel to the near future is possible, and that neither he nor anyone else will ever be able to travel backward in time. Citation needed on that one, though. Evanh2008 ^{(talk|contribs)} 03:43, 22 July 2012 (UTC)

How is steam weighed?

The article for New York City steam system says "Roughly 30 billion lbs (just under 13.64 megatons) of steam flow through the system every year". How is steam weighed? Dismas|^(talk) 14:30, 21 July 2012 (UTC)

By conservation of mass, the amount of steam out is equal to the quantity of water in. You may also find steam quality interesting: for a specific sample of steam, it is possible to derive the percentage that is gaseous water and the percentage that is liquid water in suspension, because that affects thermodynamic and other properties. For a given pressure and temperature, "wet" steam is less energy-dense, and therefore less efficient for engineering purposes (e.g., produces less mechanical work) than dry steam. Nimur (talk) 14:58, 21 July 2012 (UTC)

That makes sense. Thanks! Dismas|^(talk) 15:02, 21 July 2012 (UTC)

missing sub-topic under either Buprenorphine or Substance Abuse on "Methods of detxiing off of Long Term Buprenophine Maintenance"

This information is going to be more and more needed as the tidlewave of Opiate users are switched from Methadone to High Dose Buprenorphine, not for detox, but years of maintainence. The missing topic is very specific and almost impossible to find anywhere except on Scholorpedia where they have an article on this. The missing information or sub-title is "METHODS OF DETOX FROM YEARS OF HIGH DOSE BUPRENORPHINE USAGE"? Even with 18 years of pharmacology experience I've had, and even the so called "Certified MD's" who prescribe it don't even know. My MD said when I told him that I need to get off as I can no longer afford to take them said, "oh, just take a half every other day" which is ludicrous when your on 16 to 24 mgs a day. I've been on it over 5 years and big money is being made due to the forementioned MD's don't take insurance and the new sublingual filmtabs cost $510.00 US dollars at CVS the number 1 retail Pharmacy in the US for a ONE MONTH SUPPLY ! Also besides that issue, under buprenorphine, the new film tabs that have come out at the aforementioned price needs adding, and also the Patent on 'Subutex" but not Suboxone has expired, and with a coupon I get the generic Subutex for only $182.00 which is a cost savings of 328.00 dollars. If you show your MD the proof, and you've always been clean on your urine tests, a compassionate MD will Prescribe the genric for you which works really well. Just sharing some new info. Utilize, research, or trash whatever you want. Sincerely, A WIKIPEDIA FANATIC (I JUST LOVE THIS SITE SO THATS WHY I'm trying to help.) — Preceding unsigned comment added by 70.119.99.213 (talk) 19:10, 21 July 2012 (UTC)

Or you could just move to a country with a civilised (or semi-civilised) health system. 16mg of buprenoprhine a day costs me £21 a quarter, and if I were on benefits or poor then it would be entirely free. Anyway, what's the question? Egg Centric 19:13, 21 July 2012 (UTC)

It sounds like you found the info you need, and don't have a Q for us, so I'll mark this resolved. StuRat (talk) 19:14, 21 July 2012 (UTC)

Resolved

When people comment on information they think is missing from our articles, we should direct them to the article's talk page (Talk:Buprenoprphine in this case). Raising a point on the Reference Desk is unlikely to lead to any improvement in the article -- it happens sometimes, but not often. The personal anecdote doesn't have much value for that purpose, but pointing out things that are missing is one of the primary purposes of a talk page. Looie496 (talk) 00:03, 22 July 2012 (UTC)

Micro-stuttering and perceived frame rate

According to this Tom's Hardware article, the effect of micro-stuttering on the perceived frame rate is more severe at lower nominal frame rates -- that is, the perceived frame rate goes down faster than in inverse proportion to the longest delays between successive frames. Is there anything in the psychological literature that confirms and quantifies such an effect? NeonMerlin 22:26, 21 July 2012 (UTC)

If the frame rate is slower to begin with, then you are more likely to notice discontinuities in it. http://jn.physiology.org/content/103/1/230.long maybe? 75.166.200.250 (talk) 05:00, 22 July 2012 (UTC)

Will-o'-the-wisp

Is there a scientific explanation for why will-o'-the-wisp marsh gas lights move away as the observer approaches? I don't understand why it wouldn't be possible to walk right up to the marshlight and watch it burning from close by. 174.88.8.149 (talk) 23:35, 21 July 2012 (UTC)

Is that even true? Can you point to a reputable source that says so? Looie496 (talk) 02:30, 22 July 2012 (UTC)

That is what it says in the article here. I am asking you for sources. If I could find them on my own I wouldn't have to ask here. 174.88.8.149 (talk) 03:20, 22 July 2012 (UTC)

The article says specifically that the will-o'-the-wisp "is said to recede if approached". I'm guessing that it's "said" to do this in the same way Bloody Mary is "said to appear in a mirror when her name is called multiple times". In other words, such claims are nonsense. I don't blame you for inquiring further, though. Evanh2008 ^{(talk|contribs)} 03:25, 22 July 2012 (UTC)

Will-o'-the-wisps are anecdotal and thus are not always the same phenomena. And actually they have been observed up close. There's a very interesting article by the late 19th century British scientist Charles Tomlinson regarding them (see Charles Tomlinson (1893). A. Cowper Ranyard (ed.). "On Certain Low-Lying Meteors" (PDF). Knowledge: An Illustrated Magazine of Science. Simply Worded—Exactly Described. 16 (New Series, Vol. III). Witherby & Co.: 46–48., note: "meteor" is an archaic scientific term for atmospheric phenomena). In the article, he recounts a Major Blesson from Berlin who made observations on ignes fatui in marshlands in a forest in Neumark, Germany. By day the water in the marshland was visibly bubbling with gases rising to the surface. By night, bluish-purple flames are seen at the surface. Here's an account of a closer inspection of the flames:

On visiting the spot at night, the sensitive flames retired as the major advanced; but on standing quite still, they returned, and he tried to light a piece of paper at them, but the current of air produced by his breath kept them at too great a distance. On turning away his head, and screening his breath, he succeeded in setting fire to the paper. He was also able to extinguish the flame by driving it before him to a part of the ground where no gas was produced; then applying a flame to the place whence the gas issued, a kind of explosion was heard over eight or nine square feet of the marsh; a red light was seen, which faded to a blue flame about three feet high, and this continued to burn with an unsteady motion. As the morning dawned the flames became pale, and they seemed to approach nearer and nearer to the earth, until at last they faded from sight.

So one explanation (if it is swamp gas) is that the gas disperses easily on nearby movement. Blesson apparently repeated similar experiments in other marshlands. Succeeding in actually creating ignes fatui on a couple of occasions by firing rockets over marshlands. Here's another account by a reader's letter from a certain Charles Nielsen of Hartlepool of a similar phenomenon again caused by ignited methane:

Three miles north of here there is a small deep dam, which serves as a reservoir to supply the railway company with water for their locomotives, and on which I, with a few friends have skated, whenever it has been sufficiently strongly covered with ice, for many winters past. It has been our custom to take a borer with us and make a small hole on the centre of the ice, through which a stream of CH₄ issues and which we ignite by applying a lighted match, when a pale blue flame, rising occasionally to a height of three feet, appears; in bright sunshine this becomes practically invisible, but it is undeniably very hot.

Modern science of course explains it now as phosphine igniting on contact with oxygen and touching off nearby methane gases (see Roels, 2001). But to underline the fact that ignes fatui are usually various phenomena, here's a starkly different recounting by a certain Richard Taylor (also from reader's letters in reply to Tomlinson), while out camping on a rainy night in New Zealand:

No sooner, however, had the men fallen asleep, and the fires began to die away, than a light was observed, like the moon shining through a chink. There was no moon, and the night was very dark. On a closer examination the object appeared as a globe of pale light attached to the point of a palm leaf which hung from the roof. Another ball of light was now seen, attached to the wet sleeve of a shirt hung up to dry. "The air appeared to be charged with these luminous vapours, for while regarding the two in the shed a series of them floated past at an elevation of about a yard from the ground." These and similar phenomena, which are evidently electrical, the author endeavours to trace to the remains of the highly resinous Kauri pines which abound in the place.

His account, in contrast, seem to be the far more mysterious phenomenon known as ball lightning. And that in contrast seem to have no problems being approached, as evidenced by accounts where people or animals are actually injured or killed on contact with them.

And lastly ignes fatui, like UFO sightings, can be anything from legitimate unknown natural phenomena (see F. St-Laurent, 2000 for example of a description of strange lights after the 1988-1989 earthquakes in Saguenay, Quebec), hoaxes, hallucinations, or caused by other more mundane things. A swarm of fireflies mistaken for an ignis fatuus will fly away when approached. Or more hilariously, it may simply be other people carrying lanterns or torches through fog, who upon seeing each others' lights promptly flee from each other in terror. :D -- OBSIDIAN†SOUL 03:47, 22 July 2012 (UTC)

I'm partial to the fireflies. Excellent answer! The article needs a {{cn}} tag on the statement in question. 75.166.200.250 (talk) 05:12, 22 July 2012 (UTC)

I think we can expand the article with the above (at least Tomlinson's account). I'll try to insert it under the Scientific explanation section.-- OBSIDIAN†SOUL 05:44, 22 July 2012 (UTC)

I linkified the title. StuRat (talk) 06:05, 22 July 2012 (UTC)

The type which moves as approached suggests some form of optical illusion to me, like a rainbow or mirage, which also move or disappear as approached. The gas explanation could work, too, though, especially since many flammable gases can only ignite within a narrow range of percentages of gas and oxygen, and any nearby movement would tend to change that. StuRat (talk) 06:09, 22 July 2012 (UTC)

Alright, I've significantly expanded the scientific explanations section of the Will-o'-the-wisp article, including earlier experiments by Volta, Priestley, Saint-Lazare, and Blesson. Feel free to copyedit (or expand further) if necessary. -- OBSIDIAN†SOUL 07:32, 22 July 2012 (UTC)

Oh, and I also found an online copy of Blesson's original paper. It's definitely worth a read.-- OBSIDIAN†SOUL 07:37, 22 July 2012 (UTC)

Wow!! That is the best answer I have ever received here and that you fixed the article is amazing. Thank you!! 174.88.8.149 (talk) 13:11, 22 July 2012 (UTC)

yw :) -- OBSIDIAN†SOUL 14:37, 22 July 2012 (UTC)

Has the Altair spacecraft been cancelled?

So I was reading the article on the article of the Altair lander. It is stated that Project Constellation was cancelled, except for the Orion spacecraft and the Altair lander. While Orion is still in development, the tense used in the Altair article implies it was cancelled, despite the article stating that it hasn't. Also, I saw other articles saying that Altair is indeed cancelled. Once and for all, has it been cancelled or not? Narutolovehinata5 ^tccsdnew 23:36, 21 July 2012 (UTC)

My understanding is that Orion is still going, but isn't actually projected to be sent to the moon. Thus, Altair would become slightly superfluous to the project. It's probably cancelled, but I'm not sure I can find a source that supports that. It's really amazing how little coverage Orion is getting nowadays; the whole project is probably NASA's best kept secret. Evanh2008 ^{(talk|contribs)} 01:08, 22 July 2012 (UTC)

Space.com specifically talks of Altair in the past perfect tense ("would have" gone to the moon, etc.). However, I haven't been able to find any specific sources on its cancellation. It probably was scrapped at the same time as Ares and the rest of Constellation. Evanh2008 ^{(talk|contribs)} 03:37, 22 July 2012 (UTC)

Yes, the current US government manned spaceflight plans are to take the Orion CEV to asteroids. There's nothing even vaguely useful on the Moon or any other planet or moon short of Titan. In contrast, at least 5% of asteroids are expected to be rich in ice and dry ice cores, along with metals in similar proportion to those in the Earth's crust. Asteroids are also the only cost effective source of radiation shielding needed for viable manned space stations beyond Low Earth Orbit. Those asteroid resources are much more accessible for space utilization than anything in Earth's gravity well or on the Moon or any other planet or moon (not counting skimming hydrocarbons from Titan, which isn't really practical until the asteroids are harnessed, and isn't really necessary until deployment of a fleet of replenishable-propellant construction robots which may be likely to skim from Titan if asteroid fluids aren't practical.) 75.166.200.250 (talk) 03:50, 22 July 2012 (UTC)

Actually, there is water on the Moon, which is helpful if you're interested in producing oxygen via electrolysis, either for breathing or for fuel purposes. Producing these things in a low-G environment is extremely useful for reducing fuel costs during lift-off. Helium is also present in significant quantities and has a few more uses than just birthday parties. The Moon is also rich in silicon dioxide and numerous other materials that would be quite useful for establishing a permanent presence in space. It's also only three days away, whereas the asteroids take a significantly longer period of time and a greater amount of fuel to access. To sum it up, there are all kinds of reasons that the Moon is a better target for space exploration than the asteroids at present, including a few that I didn't mention. Titanian hydrocarbons are promising, of course, but are a long way off right now. Evanh2008 ^{(talk|contribs)} 03:58, 22 July 2012 (UTC)

I'm pretty sure that asteroid water is orders of magnitude more accessible than lunar water, both on a time and energy basis per liter. Of course there are a lot of unknowns, but just going by mean estimates, many of the asteroids are old comets likely still composed of more than 20% water under a rocky crust, if comet 103P/Hartley is typical. There is only one way to find out. I'm not a fan of lunar or martian colonies for their own sake, and would much rather have a shielded space station to establish a permanent presence in deep space because of the extent to which it would show how interstellar sleeper ships might be feasible. I am in favor of terraforming Mars, but prior to establishing a colony there, and that is likely to take many hundreds of years. 75.166.200.250 (talk) 04:24, 22 July 2012 (UTC)

I hear you on the interstellar stuff and on terraforming, and I sort of look at lunar colonies as a means to those ends. The problem with Apollo was that once it was finished, it was over and the US had no real incentive to go back. Once you begin actually colonizing the moon and exploiting its natural resources, you do have an incentive to be present on a continual basis. Starting strong in the local neighborhood and branching out from there seems to be the best path possible to me. The asteroids can and should be part of that, of course, but lunar colonisation is more conducive to deep space travel than most people realize, simply because you can manufacture things there and launch them at a far lower cost than you ever could on Earth. Lagrange point space stations, for example. You may be right about asteroid water, though. I'd have to do more reading to be certain on that point. Evanh2008 ^{(talk|contribs)} 04:29, 22 July 2012 (UTC)

I would vote for Moon colonization. You can protect yourself from radiation by building underground, and the light gravity on the Moon makes work easier than the near zero gravity on an asteroid, where tools float away etc. You could also get enough exercise to stay healthy on the Moon, say while moving objects 6 times heavier than those you could move on Earth. This wouldn't work on an asteroid, as the inertial mass would be too much to handle. StuRat (talk) 22:24, 23 July 2012 (UTC)

Gold and non-gold pendants together?

I've been wanting to buy a pendant from Shapeways, but I'm unsure of which material to select. I normally wear a necklace with five other charms. The charms and necklace are gold, but I can't say what percentage gold they are. I've worn this necklace nearly every day for five years, and I haven't noticed any wearing down of material / corrosion / what have you. The current state is durable for the foreseeable future.

It's adding another, dissimilar pendant that has me a little worried. Would adding a steel or silver pendant adversely affect the other pendants? What if the new pendant is only gold-plated? Will the gold plating last under such conditions? These are the materials that Shapeways offers, though the only ones available to use on the pendant are the top row, steel (with its finishes), and silver. The last thing I would want is for anything to damage anything else. Thanks for your help.--The Ninth Bright Shiner 23:42, 21 July 2012 (UTC)

What type of damage do you mean ? If you mean scratching the gold, then you want to avoid anything much harder than gold. Silver isn't too hard, compared with the most common gold alloys, but steel is, so I'd avoid that. You should also space the charms far enough apart that they don't strike each other while you wear it (but of course they still can when you take it off). If you meant damage due to galvanic action, I don't think that would be a concern with any of these materials, I'd be more worried with copper, brass, bronze, and aluminum.

As far as gold plating goes, yes, it will wear off eventually, starting at the corners. How long it lasts depends on thickness and usage. StuRat (talk) 23:50, 21 July 2012 (UTC)

Hmm. The charms are constantly in contact with each other; there isn't really any spacing between them. I wouldn't want to replace or discard worn-down gold plating. Add to that I don't really want a mismatched charm on the necklace... it looks like I won't be purchasing that pendant, at least with my current plans in mind. :( Thanks for the info!--The Ninth Bright Shiner 04:27, 22 July 2012 (UTC)

You're welcome. Can't you get new charms made the same way as the old ones ? A jeweler can tell you what percentage of gold is in your current charms. StuRat (talk) 06:12, 22 July 2012 (UTC)

I doubt I could get this new charm made like the old ones. The closest I could get from Shapeways, the manufacturer, is steel plated with gold. Can you take any old charm to a jeweler and have a similar one made in a new material? Unlike some products from Shapeways, this charm isn't terribly complex...--The Ninth Bright Shiner 17:42, 23 July 2012 (UTC)

Custom made jewelery is likely to be prohibitively expensive. Steel plated with gold will eliminate the scratching problem (at least until the steel wears off). If you do get such a charm, try to find one without sharp corners, so it will wear more evenly (that wounded heart one isn't bad, but will wear a bit more at the point on the bottom and on the band-aids/plasters). StuRat (talk) 22:13, 23 July 2012 (UTC)

Production of chemical fertilisers

This question was asked at talk:fertilizer, so I've moved it here. SmartSE (talk) 23:49, 21 July 2012 (UTC)

This article lacks information on how chemical fertilzers are made. It would be nice if someone knowledgable on the subject would elaborate this subject. I have heard that chemcical ferilizers are derived from crude oil. If that is the case I can not see that using it would violate organic principles since crude oil is the waste of feces of ancient animals. 2602:306:C518:62C0:290F:5E4E:7E60:2AD6 (talk) 19:43, 21 July 2012 (UTC)

That strikes me as a reasonable comment to have on an article's talk page, given that it directly relates to the content of the article. Looie496 (talk) 23:57, 21 July 2012 (UTC)

There is a wide variety. Some are synthetic, but most such as potash or fixed nitrogen, potassium, and nutrient compounds are merely refined from minerals, animal waste and byproducts, or sewage. Ammonium nitrate is mostly synthetic these days. 75.166.200.250 (talk) 05:06, 22 July 2012 (UTC)

Actually oil isn't the feces of organisms, it's the bodies of various once-living organisms (mainly plankton and algae): see Petroleum#Formation. --Colapeninsula (talk) 16:08, 22 July 2012 (UTC)