Wikipedia:Reference desk/Archives/Science/2008 November 24

= November 24 =

Motion of gas atoms
What makes un-ionized gas atoms want to get away from each other? It takes force to bring them closer together (as when being pumped into a container), or gravity to keep them close together in the atmosphere of a planet. If two gas atoms are 1,000 light years apart, and no other force is acting on them, will they move away from each other? —Preceding unsigned comment added by 98.16.67.220 (talk) 01:25, 24 November 2008 (UTC)

(I added a subject line for your question). SteveBaker (talk) 01:40, 24 November 2008 (UTC)


 * The pressure in a gas is due to the molecules bouncing off of each other and creating a net outward force. The more gas you confine in a limited amount of space, the higher the probability of a collision - hence higher pressure.   If you make the gas hotter, the molecules move around faster - which makes them collide with greater force - hence increased pressure.  When two molecules are a thousand lightyears apart - the probability of them colliding is spectacularly low - so the pressure is also astronomically low...it's not QUITE zero though.  Pumping gas into a container against the pressure takes energy because as the pressure increases, more molecules try to escape back out again by smacking into your pump mechanism - opposing the motion you are trying to impart onto the pump.


 * What we see at the 'macro-scale' as temperature and pressure - is really just motion and kinetic energy at the 'nano-scale'.

SteveBaker (talk) 01:40, 24 November 2008 (UTC)


 * If gas atoms bounce off each other, they must have elasticity. What do we know about this elasticity? Do some types of gas (types of elements) have more elasticity than other types? Also, what keeps solid material from flying apart, the way a mass of gas would if free to expand? Atoms might be held in a crystal structure, but what keeps the crystals together in a solid? Also, not all solid material is crystaline. —Preceding unsigned comment added by 98.16.67.220 (talk) 02:15, 24 November 2008 (UTC)


 * If those two gas atoms 1,000 light years apart are stationary with respect to each other, they would never come together and bounce apart. Thus, there is no pressure. —Preceding unsigned comment added by 98.16.67.220 (talk) 02:40, 24 November 2008 (UTC)


 * It's not gas molecules bouncing off each other, it's gas molecules bouncing off the walls. Imagine you have two fixed parallel plates and a single elastic ball bouncing between them. Assume negligible friction and gravity, so the ball will bounce back and forth pretty much forever. Each time it bounces off one of the plates it exerts an outward-directed impulse on that plate. The size of the impulse is always the same, but the time between bounces is proportional to the separation of the plates, so the average impulse per unit time (i.e. the force) is inversely proportional to the separation of the plates. Extend this to three-dimensional motion and add a bunch more elastic balls that never collide with each other and you have an ideal gas. -- BenRG (talk) 03:04, 24 November 2008 (UTC)


 * To expand on this and on the OP's original question; the gas atoms ARE attracted to each other, but they are simply moving too fast to "grab on" as they whiz by each other. Do this thought experiment.  Imagine you and your friends are walking towards each other down a hall way.  You each reach out and grab each other's hand as you pass each other.  Is it hard to garb them and hold on?  Now, imagine the same experiment, but now your each standing on the bed of a truck moving down the highway at 90 miles per hour at each other.  You and he haven't changed, but you're just moving to damn fast to effectively stick to each other.  To translate this to gases (vs. the condensed phases of liquids and solids) the molecules in a gas are just as attracted to each other as they would be in the liquid state of the same material.  The difference is that the gases have so much kinetic energy, that this is higher than the binding energy that would be released should they actually form bonds (that is, stick to eachother and form a liquid).  Thus, they never get to stick together... --Jayron32. talk . contribs  03:22, 24 November 2008 (UTC)


 * It's really a stretch to talk about atoms that far about in that much of a vacuum - but let's roll with it. The molecules in a gas can only be completely stationary if the temperature is absolute zero...that's what "no motion" means. No kinetic energy whatever...no energy means no temperature - so absolute zero.  However, the laws of thermodynamics don't allow things to be at absolute zero...but...things get a bit fuzzy when you put just two molecules so far apart - we get into the problems of simultaneity and relativity and all sorts of other complicating factors.  So if there has to be the tiniest amount of motion - then over a very long time, there can still be a collision so TECHNICALLY, the pressure isn't zero.  And this can only be a thought experiment - even in the deepest depths of space and in the hardest of 'hard' vacuums, there are plenty more atoms floating around than that.  SteveBaker (talk) 03:23, 24 November 2008 (UTC)

Preventing propagation by cutting
Can plants be genetically engineered so that they can't be propagated from cuttings, or so that doing so will lower crop yield or agricultural ROI? Neon Merlin  23:39, 23 November 2008 (UTC)


 * Hmmm, if you screw with the cellular differentiation mechanism, that whould pretty much prevent propagation by seed as well. Rooting relies on the stem cells (that is, non-specialized cells; not the cells of the plant stem!) producing/becoming specialized root cells of various types. The same mechanism allows the plant to repair most types of tissue damage. If you knock out parts of this mechanism, plant will be less resilient. Maybe modern GM can do something far more subtle; I don't know. These are just my thoughts, though. I may definitely be wrong on this one, so beware. --Dr Dima (talk) 00:10, 24 November 2008 (UTC)
 * You could also mess around with the expression of Plant hormones instead which could knock out some of the specific cellular mechanisms that is involved in tissue regeneration.-- Lenticel ( talk ) 01:40, 24 November 2008 (UTC)
 * Do you exclude grafting? There are plenty of plants which can only survive as a graft but they could I guess be propagated if you also propagate the root stock and grafted them. --BozMo talk 15:06, 24 November 2008 (UTC)
 * If you want an example try googling for the Cactus called "red top" with is a chlorophyll-free cactus which can only live as a graft on a green stem. I am a bit surprised this whole category of plant doesn't seem to be in Wikipedia yet although there is mention in the article on Gymnocalycium --BozMo talk 15:09, 24 November 2008 (UTC)

Differences it doesn't make
What are the most important aspects of human psychology that Asperger Syndrome does not affect? Neon Merlin  01:55, 24 November 2008 (UTC)


 * Love, happiness, humor...lots of things. Please remember though that Aspergers and Autism are a spectrum of conditions.  At one extreme, the person may be so nearly normal as to appear to have only the tiniest difference - such a person has almost none of "normal" human psychology disrupted.  At the other end, you have full-blown autism where the victim is completely cut off from other people and quite utterly unable to function - just about every aspect of normal psychology is severely impacted.  In some vague, fuzzy region between those two extremes, we have true "Aspergers" - but people who are labelled in that way are really wildly varied.  Some people I've met have a huge range of problems - can't hold down a job and are really kinda weird to deal with.  Others have something so mild that I'd hesitate to describe it as a "syndrome" at all.  I don't think I could give you a straight answer. SteveBaker (talk) 02:59, 24 November 2008 (UTC)


 * From just a few cases I've encountered I'd say some type of deductive reasoning. Although they can limit the factors they accept in their consideration and sometimes violently defend "wrong" conclusions, they do some form of A plus B equals C.  This can come in the form of "I'm looking for C so I need A and B to happen." - which sometimes leads to "odd" behavior.  E.g. heat plus light (summertime) = ice cream; may cause someone to turn on lights and turn up the furnace before having/accepting ice cream when it's not summer or insisting on ice cream for every desert on hot, bright days.  Some savant abilities are related to people seeing the whole lion from just a hair of the mane or hear a symphony from one note. 76.97.245.5 (talk) 04:14, 24 November 2008 (UTC)


 * Those things are certainly on the more extreme end of the spectrum (I have a more moderate form of the syndrome and I'd certainly never fail in the manner you describe - although I certainly do have 'issues'!). But our OP is asking for things that ARE NOT affected by the syndrome.  Deductive reasoning is certainly one of the more major things that IS affected.  In mild to moderate Aspergers, deductive reasoning is often vastly improved because of the ability to focus on a very small topic for extended periods while shutting out distractions - in serious cases, it's devastated in the manner you describe (although that's perhaps reaching the the point where you should properly describe the condition as 'Autism' rather than 'Aspergers').  But either an improvement or a worsening counts as "affecting" that aspect of psychology...so we're still not answering the OP's question. SteveBaker (talk) 14:59, 24 November 2008 (UTC)


 * The effects could be positive as well as negative, such as ability to be detail oriented in a job which would bore some people, or a tendency toward scholarship. Edison (talk) 19:41, 24 November 2008 (UTC)

Children's game
I just remembered a game when I was young. Basically, we push air to our mouth to build up pressure. When we can't handle the pressure, we slightly open our mouth. That would supposedly release a "puff of smoke" (probably condensed water vapor). So what principles do we use to produce the puff and would it even be possible since I still can't do it? I'm thinking that by releasing the pressurized air, we are cooling it thus causing condensation. However, I don't think the mouth cavity is capable of withstanding that amount of pressure. Notice that I live in the tropics so condensation via cold weather is out of the question.-- Lenticel ( talk ) 04:01, 24 November 2008 (UTC)
 * In my experience, the outside air needs to be below 12 degrees Celsius to make visible condensation. Your theory could explain it, though I would be surprised that this would work in the tropics.  Perhaps you had just inhaled a burning cigarette? Graeme Bartlett (talk) 04:19, 24 November 2008 (UTC)
 * I think my buddies at my elementary days have no resources to buy cigarettes but there is a possibility (not sure) that they snuck in a smoldering match in their mouth instead when I wasn't watching. (but that's unfair : -- Lenticel ( talk ) 04:55, 24 November 2008 (UTC)


 * There are places in the tropics where the temperature drops that far at night. In the middle of the Sahara desert, temperatures often drop below freezing at night...so condensation of breath in the early morning is still very possible - and that does seem like by far the most likely explanation. SteveBaker (talk) 14:52, 24 November 2008 (UTC)


 * I haven't tried this, but you might also be able to make it work by drinking something hot and then exhaling the resulting steam, although that too would probably work best if the ambient air was fairly cold. Or the "smoke" from the mouth might be fine droplets of water/saliva. 69.224.113.5 (talk) 21:18, 26 November 2008 (UTC)

Non-persistent UV dyes
Does anyone here know of any paints or dyes which are strongly reflective in the ultraviolet range, but relatively transparent in the visible? Are there any such dyes which are "non-persistent" in the sense that they only last on the order of days before dispersing/evaporating? The application of this will be for "virtual" pheromone trails, which need to be invisible to humans (people might not like lines all over their carpet). The reason for the non-persistence is so that bad trails will eventually disappear if they are not renewed. The surface for these trails will probably be some sort of carpet. Someone42 (talk) 07:26, 24 November 2008 (UTC)


 * A thin dusting of pollen might work. Although if I remember they are rather black in "bee vision" renderings than reflective. Would a dark trail work for you?? "Post it" glue might do the trick for keeping it in place for a while. 76.97.245.5 (talk) 08:01, 24 November 2008 (UTC)


 * Many laundry detergents contain substances that glow under black light. You could dilute a sample and try painting a portion of the carpet.  It should be safe to use on your carpet, but I'm not sure how long it would last though.  Dragons flight (talk) 15:53, 24 November 2008 (UTC)

The chemicals you're looking for are a class of fluorescent dyes called optical brighteners. They absorb UV light and emit white/blue light - this is the stuff that makes your clothes glow under UV/'black' lighting. The light emitted is effectively invisible in normal light conditions. The dyes used in laundry detergents and fabric softeners do not attach strongly to fabrics.Bobzchemist (talk) 15:36, 26 November 2008 (UTC)


 * Before this question disappears off the top of the refdesk, I'd like to say thanks to all those who answered. Someone42 (talk) 07:46, 30 November 2008 (UTC)

on improving economy using science
Tell me of a possible project to be done that is theoretical on physics that can be done to improve the economy It may be a machinery that I would like to present in the next year science congress in Kenya.[www.Pelly properties.com] - 0713403690 -


 * There was a French physicist Pablo Jensen (with the Ecole Normale Superieure in Lyon) who used math to determine ideal locations for bakeries based on criteria he extracted from ones who succeeded and ones that failed. You might start similar things for farms, plantings, general stores etc. for your area.  This isn't a great link    - maybe s.o. else has a better one.  (Physical Review E (Vol. 74, p. 035101)  Here's a quote from some article "... the Chamber of Commerce in Lyon is using his mathematical index to help small business owners determine the best locations for new stores..." 76.97.245.5 (talk) 10:08, 24 November 2008 (UTC)


 * You may want to have a look at the Econophysics article. EverGreg (talk) 11:47, 24 November 2008 (UTC)

Calories
It is generally reccommended that one eats 5-6 small meals a day rather than 2 or 3 huge ones far apart, in order to keep hunger levels down. Another reason for this is that eating food encourages the burning of calories; if you eat a large meal and go without for some time, your body will reduce calorie burning in order to conserve energy. If this is true, is it true that if you feel pangs of hunger, your body is starting to reduce the rate at which it burns calories and is also storing food as fat in preparation for starvation?

The reason I ask is I generally don't feel hungry 5-6 times a day even on small meals, yet I generally try and eat regardless in order to stop my body from thinking its starving. Should I keep a consistent meal intake regardless of how I feel or (more preferably) eat when my body starts to show signs of hunger? 81.187.252.174 (talk) 11:13, 24 November 2008 (UTC)


 * The Ref Desk cannot provide medical advice. For questions of what you personally ought to do, consult a qualified physician / dietitian / other-ition.  It's worth noting that when we previously covered this topic, we noted a lack of controlled trials to establish whether there was any validity to the small meals theory.  &mdash; Lomn 14:38, 24 November 2008 (UTC)


 * Dietary advice is NOT medical advice. If it was, it would be illegal for those lacking a medical degree to offer dietary advice, as it is for them to prescribe medications. StuRat (talk) 15:38, 24 November 2008 (UTC)


 * If it was really, really bad for you to eat only 3 times a day, then the French would all be dead. Itsmejudith (talk) 15:09, 24 November 2008 (UTC)


 * I'd say wait until you're hungry, then eat a small meal. If that works out to be 5-6 meals a day, fine.  If it's only 3, that's fine, too.  Eating when you're not hungry doesn't normally seem like a good idea, however. StuRat (talk) 15:38, 24 November 2008 (UTC)


 * If you want to eat fewer calories, then you need to eat fewer calories. The question of controlling hunger is simply a mind game that may make this easier for some people.  You should eat however many meals makes it easiest for you eat the total amount of food that you are shooting for.  Personally, I think it would be easier to keep track of 2-3 meals a day, than to track 5 or 6, but from the point of view of what your body does with that food it really makes very little difference.  Dragons flight (talk) 17:15, 24 November 2008 (UTC)

Plant Identification
What is the name of this plant? Thanks--Abhishek Jacob (talk) 11:42, 24 November 2008 (UTC)
 * Um, it's there in the image name—Strobilanthes kunthiana, commonly known as neelakurinji. Deor (talk) 12:54, 24 November 2008 (UTC)

Oh, forgot to mention it. Its a nominee for featured picture. The photographer is not sure it is Strobilanthes kunthiana. So I put it here to make sure.--Abhishek Jacob (talk) 13:37, 24 November 2008 (UTC)


 * It seems more blue cast than these. Perhaps it's another variety. Julia Rossi (talk) 07:30, 25 November 2008 (UTC)
 * The flowers (and leaves) seem to match the ones in this photo and this one, though, as does the fuzzy stuff in the interior of the flower. ("Fuzzy stuff," how scientific!) The pistils do look a bit different, however. Deor (talk) 13:37, 25 November 2008 (UTC)

Skeleton's kids
Say an archaeologist finds a female skeleton in a grave. Would it be possible for the archaeologist/forensics specialist to tell if that woman had children only by studying her remains ? Rosenknospe (talk) 13:02, 24 November 2008 (UTC)
 * Quite possibly; childbirth likely causes irreversible changes to the pelvis; I would imagine that one could examine the shape of the pelvis to say that it may be likely a female had had children. --Jayron32. talk . contribs 13:06, 24 November 2008 (UTC)
 * I non-expertly agree with Jayron; see Pregnancy and relaxin. --Sean 13:12, 24 November 2008 (UTC)
 * I'm pretty sure I've heard of this exact thing being done - so, yes. SteveBaker (talk) 14:43, 24 November 2008 (UTC)


 * quoting Until recently, it was thought that the formation of a pre-auricular sulcus  was related to the process of childbirth. However, the latest studies have found that childbirth is not the only cause for such marks, and in fact, they are more closely related to biomechanics, and in particular, pelvic flexibility (Cox 2000b)


 * See also where parturition is the scientific term for childbirth.  EverGreg (talk) 15:30, 24 November 2008 (UTC)


 * The above is all true so far as I recall, with the additional problem that the age and state of the remains will be a huge factor in deciding anything about the person they belonged to; in some cases, it can be difficult to even be sure of the number of remains involved. Determining from skeletal remains whether a woman had undergone childbirth has the additional issue that the pubic symphysis is not composed of bone and so more prone to eroding away. See also Diastasis symphysis pubis. The amounts of expansion given in the articles are also obviously averages which brings up problems of its own; not every woman will have the same amount of anatomical change during pregnancy or parturition, which again reduces the accuracy of forensic readings. Matt Deres (talk) 20:09, 24 November 2008 (UTC)

Okay, so I take it proving a pregnancy in these conditions is highly unlikely, bordering on impossible. Thank you very much guys ! Rosenknospe (talk) 12:02, 25 November 2008 (UTC)

Paper lens cleaning cloths
I remember when I got my first pair of glasses a couple decades ago, I was warned never *ever* to clean them with paper tissues as it would scratch the plastic lenses. Now I see single use foil-wrapped cleaning paper for eyeglasses. The paper is slightly damp an reminds me of a handi-wipe. How is this type of paper safe to clean plastic lenses, but tissues are not? --70.167.58.6 (talk) 16:14, 24 November 2008 (UTC)
 * Maybe it's smoother and/or softer? DMacks (talk) 17:17, 24 November 2008 (UTC)
 * Paper tissues (eg Kleenex), like most paper products (paper towels, etc.) are made from wood pulp and contain wood fibers that could scratch plastic. Lens cleaning tissues and the special eyeclass cleaning papers are made from cotton and are safe to use.  Another reason to use a moist cloth is to prevent any dirt or particles on the lens from scratching as you drag the dry tissue across it.  I believe most modern plastic eyeglasses have now have a scratch resistant coating, so it's not quite as important as it was but you still have to be careful.--Zerozal (talk) 18:32, 24 November 2008 (UTC)

malignancy as a blood infection?
can malignancy or tumour spread through blood transmission? —Preceding unsigned comment added by Meet poonam (talk • contribs) 16:20, 24 November 2008 (UTC)


 * The best evidence is that there is little or no risk of a person with undiagnosed cancer spreading it via blood donation . People with diagnosed cancer are excluded from donating blood in most places.  Dragons flight (talk) 16:33, 24 November 2008 (UTC)


 * Per Dragons flight, malignant cells transferred during a blood transfusion would almost certainly be identified as foreign by the recipient's immune system, and be aggressively attacked. Note, however, that some oncoviruses – viruses which can cause cancer – can be transmitted through blood transfusion. TenOfAllTrades(talk) 17:04, 24 November 2008 (UTC)


 * The study that the reference Dragons flight links to discusses, was performed by Gustaf Edgren at the Karolinska Institute. Information from the Swedish Cancer Registry, the Danish Cause of Death Registry, and the databases/backup tapes of Swedish and Danish blood banks was combined. The introduction to his thesis is a fascinating read. The answer to the OP's question is "yes, but only very, very rarely". Edgren cites three case reports of transmission of leukemia from donor to patient, and states that these are the only unambiguous reports of cancer transmission by blood transfusion. He also reviews findings from transplantation, and some spectacularly unethical experiments that have been performed. I find it surprising that undiagnosed cancer in the donor has such a low probability of being transmitted to the recipient. Many patients need transfusion because of chemotherapy, which causes both anemia and immune suppression. But Edgren's data are convincing, and the study is huge (12 million transfusions). --NorwegianBluetalk 23:16, 24 November 2008 (UTC)


 * Speaking off-the-cuff, I'd say that the poor transmission of undiagnosed cancer is not particularly surprising. Undiagnosed, non-blood cancers prior to stage III or IV probably don't have very many malignant cells circulating in the blood.  Meanwhile, diagnosis is much more likely as cancer progresses to later stages; there are relatively few undiagnosed late-stage metastatic cancers, looked at as a fraction of the total population.
 * I assume that a complete blood count is performed on units of donated blood in nearly all jurisdictions; weird blood counts would flag disorders like undiagnosed, advanced leukemia. Meanwhile, most western countries now use only leukoreduced blood for whole-blood transfusions.  Filtering out white blood cells likely also catches most other nucleated, malignant cells which might be circulating.
 * Finally, there are degrees of immunosuppression. Malignant cells transferred by transfusion are not going to be able to multiply nearly as bacteria or viruses.  It's possible that even a relatively weak immune response might be sufficient for the recipient to squelch a few foreign human cells. TenOfAllTrades(talk) 18:32, 25 November 2008 (UTC)


 * A complete blood count is not performed routinely, at least not in most European countries, and there is certainly no such regulatory requirement. The only requirement in that regard, is checking that the haemoglobin level is not below the minimum acceptable level. At least until recently, some developed countries still used the copper sulfate test - a copper sulfate solution with an appropriate concentration is prepared, the test consists in seeing whether a drop of blood from the donor's finger sinks or floats. Complete blood counts are performed routinely only on platelet apheresis donors. I agree about the solid tumours, but find it surprising that haematologic malignancies are almost never transmitted. Edgren's data was collected between 1968 and 2002. Leukodepletion was introduced in the 1990's. --NorwegianBluetalk 20:29, 25 November 2008 (UTC)

THC absorption
This question has been removed as it was a request for medical advice, which we are not allowed to give answers to, as per Reference desk/Guidelines/Medical advice Gunrun (talk) 09:10, 25 November 2008 (UTC)


 * How on Earth is this a request for medical advice? --Abin Sur (talk) 06:07, 26 November 2008 (UTC)


 * You know what? I've looked over the guidelines, and my question is obviously and clearly not applicable to the cited guidelines.  Because one may disapprove of Cannabis use does not mean one may apply irrelevant guidelines to it.  This is a scientific query about the absorption of a chemical into the system, not any medical request.  So here I repeat it:

Ages ago, I learned (from somewhere, heck if I can remember) that when smoking marijuana, it is more effective to "hold it in" for as long as possible after inhaling to maximize the amount of THC taken in. Now... is this tactic effective? Does holding it in increase the amount of THC intake versus a quick inhaling followed quickly exhaling (as in "regular" breathing)? I guess an effective way to test this would to smoke same amounts of the same strain of marijuana with the same method of delivery over an identical period of time in each test on different days... except, there are other variables involved (food in the system, surroundings and comfort, mood, etc) and it may prove difficult to properly record or quantify any results (it's a lot of work for a part-time stoner to try and process with any consistency while under the influence). --Abin Sur (talk) 17:32, 24 November 2008 (UTC)


 * Unfortunately all I've heard recently has been in the popular media, and thus can be presumed to be pushing either the pro- or anti-marijuana agenda. Anyway the last I heard was the worst thing with smoking marijuana is the fact that smokers hold the smoke in for longer than a cigarette smoker and so more damage is caused.
 * Of course, if you hold the smoke in longer there is more time to absorb the smoke. So yes. Greater effect.
 * Then again, if you eat it, it's in contact with your innards longer still. Have you got an oven and a cookie recipe? --121.127.209.126 (talk) 10:22, 27 November 2008 (UTC)
 * You're right, Abin Sur, your query did not run afoul of any applicable guidelines; its removal was unwarranted. If I recall correctly what I've read, THC absorption drops off sharply after five seconds or so. There are some high-quality references in Volcano vaporizer, some of which address this what you're curious about. —Scheinwerfermann T&middot;C 17:34, 29 November 2008 (UTC)

Doubling CO2 in atmosphere
Hi all,

If the amount of CO2 in the atmosphere were to double from it's current concentrations, about how much would we expect to see the temperature to increase? Obviously there are multiple models, but some calculation that has some reasonable consensus would be great.

Thanks! &mdash; Sam 63.138.152.238 (talk) 18:25, 24 November 2008 (UTC)


 * 3.0 +/- 1.5 °C at equilibrium (i.e. including the slow warming of the oceans): (page 35).  Dragons flight (talk) 19:08, 24 November 2008 (UTC)

Thank you. &mdash; Sam 65.96.110.73 (talk) 20:19, 24 November 2008 (UTC)


 * It's a bit tricky to know this because the temperature isn't only being driven by the CO2. At some point (possibly a point we've already passed) - there are feedback mechanisms that push the temperature higher even when the CO2 stops going up.  SteveBaker (talk) 23:06, 24 November 2008 (UTC)


 * There are also feedback mechanisms that slow down the heating of the Earth as CO2 increases. Also, the feedback mechanisms don't occur at "some point". There may be some that don't occur until certain (different) points, but most just change strength depending on the temperature and other factors. — DanielLC 16:11, 25 November 2008 (UTC)

Extreme Precision
According to its article, 3046 Molière is a main belt asteroid with an orbital period of 2029.6155869 days (5.56 years).

According to my reckoning, this period is given to a precision of about 1x10-5 seconds. Is this credible information?

Thanks, CBHA (talk) 21:57, 24 November 2008 (UTC)


 * For a minor asteroid? No.  Dragons flight (talk) 22:06, 24 November 2008 (UTC)


 * I chopped it back to something a bit more reasonable - but the original editor (User:Captain panda) appears to have created a semi-infinite number of articles about minor asteroids - all of which say nothing other than the date of discovery and an insanely high precision orbital period. I've left him a note on his Talk: page - but in truth, these asteroid articles are all about highly non-notable chunks of rock - the whole lot should probably be rolled up into a neat little table in some more significant article. SteveBaker (talk) 23:03, 24 November 2008 (UTC)
 * Given the rate at which he's created them (And has subsequently made edits to them) I think we can assume he's using some sort of script or bot. He's almost certainly got a script that scrapes the JPL Small-Body Database that he cites as a source.
 * What confuses me is why does the JPL database list all those orbits with such precision, but just list the uncertainty as "N/A"?
 * If I had to guess, I'd say that JPL has some sort of glitch in their website that's not pulling the data from their database properly. APL (talk) 23:15, 24 November 2008 (UTC)


 * It is curious that the JPL database reference and the Wikipedia stubs both give the periods in days to a very high precision but the numbers, beyond the whole number of days, are different. For example, 6102 Visby has an orbital period of 1532.0615152 days while the JPL database browser shows 1532.2319026 days.  ??  CBHA (talk) 23:42, 24 November 2008 (UTC)


 * I'd consider such asteroid info notable, but agree that the precision is a problem. When getting two different values from different sources, this gives us some idea of the uncertainty.  I'd just go with 1532 days, in this case, since it's consistent with both values. StuRat (talk) 01:25, 25 November 2008 (UTC)


 * Do we really need all of those dozens of separate 1 line stub articles?  It's pretty unlikely that any of them will ever get any longer.  The information would be better presented in a neat table someplace. SteveBaker (talk) 01:54, 25 November 2008 (UTC)


 * Exactly. At the moment none of those articles have ANY possibility of expansion past the stub stage. As such the data is probably better in a table. --98.217.8.46 (talk) 03:01, 25 November 2008 (UTC)
 * Agreed, a table would be far better. Some asteroids have had missions to them or have planned missions to them, those should get proper articles, as should any with historical or scientific significance, but the rest can just go in a table (possibly with 1000s of redirects to that table if people really want them). --Tango (talk) 13:41, 25 November 2008 (UTC)


 * Knowing an orbital period of a small asteroid to 11 significant digits does not seem to be even meaningful, as I don't believe their orbits are that regular. Their orbits are perturbed by gravitational interaction with planets and with each-other, and probably also by collisions with smaller bodies. I do not have time to estimate the amount of relative perturbation in the orbital period for a typical asteroid, but people did that sort of calculations before; if someone knows the result, please post a reference here. I'd be shocked if relative perturbations are less than 1e-10 for asteroids discussed here. What usually happens is that far-too-many-significant-digits come from the format of output of the software; in this case the software that's used to track these objects. As far as I remember, same format is used for all objects, regardless of the accuracy of the respective data. --Dr Dima (talk) 05:04, 25 November 2008 (UTC)