Wikipedia:Reference desk/Archives/Science/2008 September 5

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September 5

"base SI quantity"

I have the question: When using the words "base SI quantity for 3mg," would I be referring to "mass", or "gram"? No wiki article exists on Base SI quantity, and as and American trying to learn more about SI, this is somewhat confusing. Thanks, Spencer^T♦C 00:28, 5 September 2008 (UTC)

I don't know about "base SI quantity" but SI base units may be what you are looking for. DuncanHill (talk) 00:41, 5 September 2008 (UTC)

Oh wow, I feel stupid. Thank you very much. Spencer^T♦C 00:42, 5 September 2008 (UTC)

No need to feel stupid (everyone finds new systems of measurement difficult at first), and I am glad to be of help. DuncanHill (talk) 00:44, 5 September 2008 (UTC)

:D. Spencer^T♦C 00:45, 5 September 2008 (UTC)

By the way, the SI unit of mass is the kilogram, not the gram (don't ask me why...). --Tango (talk) 00:51, 5 September 2008 (UTC)

We did use the gram for a while - in the CGS (centimeter/gram/second) system. Now we use the MKS (meter/kilogram/second) system instead (well, strictly "SI" - which is MKS + moles, amps, candelas and kelvins). CGS was very gradually phased out from about 1880 until fairly recently (some fields still use CGS - electrodynamics being the most notoriously stubborn). Mostly because for most practical purposes the resulting numbers tended to get too big in most fields of human-scale things. It's unfortunate that we stuck with 'gram' and therefore ended up with a 'kilo' prefix on a 'base' unit - it would have been nicer if we'd just had some new unit that happened to be the same size as a thousand grams. But that's history - and we're kinda stuck with it. SteveBaker (talk) 04:54, 5 September 2008 (UTC)

I added a redirect so that it is easier to find for the next person who ties this name. Graeme Bartlett (talk) 01:44, 5 September 2008 (UTC)

Gravity question

All humans are attracted to the center of the earth by gravity. So if there was a hole drilled from the north pole threw to the south pole and I fell down it, would I end up in the middle of the earth? —Preceding unsigned comment added by 1000kA (talk • contribs) 00:45, 5 September 2008 (UTC)

Ignoring the fact that such a hole is impossible, yes. You would be weightless at the centre, since the gravity from all the matter surrounding you would cancel out. --Tango (talk) 00:52, 5 September 2008 (UTC)

Well, yes, you would get to the centre, but you would be moving very fast by the time you got there. After passing the centre, gravity would start to slow you down again, and (ignoring various things) you would end up oscillating about the centre. If we're not ignoring air resistance, then you'd end up in the centre after bouncing back and forth a bit. Algebraist 01:16, 5 September 2008 (UTC)

You'd keep bouncing as the gravity of Earth would be cancelled out, but the moon (which is powerful enough for tidal effects) would still be tugging at you - as would a weak tug from the sun which changes relative direction with your orientation to Earth as Earth spins. -- kainaw™ 01:20, 5 September 2008 (UTC)

In the pole to pole hole there would be no Coriolis force as you would get from any other places on the earth. Also the air pressure and temperature would be so high down deep, that the air would be liquid and you would be baked on the way down. Graeme Bartlett (talk) 01:48, 5 September 2008 (UTC)

Dont you mean boiled? —Preceding unsigned comment added by 1000kA (talk • contribs) 02:01, 5 September 2008 (UTC)

An interesting side note: ignoring friction etc., the time to "fall" through a straight hole between any two points on the surface of the Earth is the same as for any other two points. Saintrain (talk) 13:03, 5 September 2008 (UTC)

Darn, you beat me to it. Indeed, if you pretend the Earth is a solid non-rotating sphere of uniform density, and dig a straight shaft between any two points on the surface, and lay down frictionless rails on the bottom of the shaft, and evacuate the tube so there's no air friction, and put a train car on the rails, and let gravity do the rest, it will take you from one end of the shaft to the other in a time of $\pi {\sqrt {\frac {r_{\text{earth}}}{g_{\text{surface}}}}}$, which is about 42 minutes, independent of the endpoints. I think the acceleration you feel is also constant throughout the trip, and equal to ${\frac {r_{\text{min}}}{r_{\text{earth}}}}g_{\text{surface}}$, where $r_{\text{min}}$ is the minimum distance from the tube to the center of the Earth. (This is the acceleration that would be measured by an accelerometer that you took on the trip, which is not the same as your acceleration with respect to the rest frame of the Earth.) On a trip from San Francisco to London you'd feel about 0.78 g. I could live with that. Pretty expensive public works project, though. -- BenRG (talk) 14:19, 5 September 2008 (UTC)

I don't see how acceleration could be constant. When you start, you're at the surface, so that's 1g, in the middle you are somewhere beneath the surface, so that's less than 1g (0g if you're going between antipodal points). --Tango (talk) 18:18, 5 September 2008 (UTC)

In the case of the antipodal points, you're in free fall the whole time, and therefore feel zero g, in the sense that if you carried an accelerometer with you, it would register zero g. 1000kA, if there's enough pressure to liquefy air, there's going to be enough to keep water liquid, if not solidify it. — DanielLC 22:28, 5 September 2008 (UTC)

Mars

I have seen many pictures of mars taken over the years where abnormal structures can be clearly seen (pyramid type things among others). I would like to know why these structures have not been scientifically investigated and why NASA has not sent a probe to these interesting areas? Eg: the face on mars. If you are wondering what I’m talking about search youtube for “structures on mars” There are also areas of photos that have been clearly airbrushed, what do NASA have to hide? 203.202.144.223 (talk) 00:48, 5 September 2008 (UTC)

Please read Apophenia and Pareidolia. — BRIAN0918 • 2008-09-06 18:06Z

Have you tried reading about the "Face on Mars" here? DuncanHill (talk) 00:50, 5 September 2008 (UTC)

I have read about the face on mars as an optical illusion, however i have also read that the recent pictures were had been harshly (and unnecessarily) filtered. But there are many other pictures showing other odd things other then the 'face on mars'. I guess another question I have is why would NASA airbrush pictures of mars' surface? 203.202.144.223 (talk) 01:00, 5 September 2008 (UTC)

Another question would be why someone would want NASA, heavily funded by tax dollars, to waste money exploring ideas from some crackpots who know nothing about Mars except what they've seen in video games and science fiction shows? If the crackpots want to investigate all those artificial structures, then let them raise the money to do so. NASA is busy trying to find an optimal location for a sustainable living area should we achieve manned missions to the Mars. -- kainaw™ 01:18, 5 September 2008 (UTC)

So you do believe that those structures are artificial? Even at the minute chance they are artificial wouldn’t that be reason enough to at least investigate them? Or hey, maybe that’s just some crazy opinion of a “crackpot” 203.202.144.223 (talk) 01:40, 5 September 2008 (UTC)

This is one of those "please prove that something doesn't exist" arguments. The crackpots want proof that there are no artificial structures on Mars. If we brought Mars to earth, rock by rock, and examined the entire planet, they would still be claiming the overlooked something. It is a project that has no end and, therefore, would take forever and cost an infinite amount of money and man-hours to complete. So, the answer is a simple no. It is not worth wasting all our money and time on something that has already been examined and has already been proven to all sane people to not exist, but still gives crackpots a big fuzzy feeling when the send their little "NASA is covering this up" messages back and forth on the Internet. -- kainaw™ 01:55, 5 September 2008 (UTC)

Looking past the other issues, it is also impractical at current. After travelling 150 million kilometers, the mars landers come down with a targetting precision of +/- 50 km. I suspect that visiting most "structures" you'd like to look at would be challenging if your starting point is only good to within 50 km. Dragons flight (talk) 02:09, 5 September 2008 (UTC)

Sad, but true - these things are worth a quick check - and NASA have done that. In the case of the "face" they took higher resolution photos - which look NOTHING like a face. They apply an appropriate amount of diligence - but once they've proved to a reasonable degree of certainty that nothing interesting or unusual is going on, they drop it.

Sadly, the nut-jobs on the conspiracy sites simply won't ever give up their crackpot ideas. Check out the "The moon landings were faked" loonies...we have a freaking great HUGE pile of moon rocks in a lab in Houston - I've seen them. There is even a moon rock that you can actually touch. We have movies that can't be faked without genuine low gravity conditions. We have retroreflectors on the moon that you can bounce lasers off of that prove we put man made stuff there. We have brave, honest men with no history of lying or conspiracy who tell us what it was like to be there. We have literally tens of thousands of people who would have all have to have agreed to the conspiracy - and NOT ONE of them has ever confessed to lying or concealing the truth - not even on their death-beds. We have really solid counter-arguments to absolutely every single complaint the crackpots put up...but still, I don't believe that we've ever convinced a single one of them. It's fair enough that you might come up with some strange things you see in those photos (non-parallel shadows, no stars in the photos, etc). But when I successfully explain all of them, you need to say "Oh! Well, then you must be right." - you don't go back, find ANOTHER dozen tenuous things - let me explain those, then find ANOTHER dozen (even more tenuous) things.

There is no way to get rid of these people - no amount of proof will ever make them believe. Would you believe there are still flat-earth believers? Yep - there is an entire web site full of them. You say - but there are guys up there in orbit right now looking down at the earth and they say it's round. They say "So have YOU ever seen that?...Then how do you know?"...then an actual astronaut who HAS been there and seen it says "Yes! I've seen it with my own eyes."...and they say "Ah - but it was an optical illusion due to refraction of light though the atmosphere"...and you say "But refraction bends light in the opposite direction"...and they say "Sure it does in the lab - but have you tested that in the upper atmosphere?". You say "But what about ships disappearing over the horizon?"...and they say "Ah - diffraction through the atmosphere" - and you say "But diffraction bends light the other way...and you just AGREED that it works my way"...and they'll say "But the water vapor alters the sign of the pseudo-magnetic wibble matrix because of quantum grungology and that's why it does it."...and off we go again.

It's an eternal regression - they can come up with crazy crackpot special-case exceptions and toss in random pseudo-scientific babble no matter what. When you do knock down their arguments - they ignore that and move on to an even crazier claim. They pretty much universally don't understand enough science to comprehend why your counter-arguments are valid.

At some point, you have to say "You're an idiot." and move on...doubly so if you are a government funded agency who will get in deep trouble if you spend a few megabucks on proving some crackpot wrong.

So - the 'features' on Mars are no different from seeing bunny rabbits in the clouds. The human visual system has a built-in feature that forces you to try to find pattern in anything you see. Most of the time, this is useful - but sometimes it makes you see faces on Mars, bunnies in clouds, and allows small children to scare themselves silly at bedtime by seeing monsters - which turn out to be shadows cast by toys or whatever.

You can keep on demanding more and more proof - but there comes a point when you're going to be labelled a "crackpot" - and with good justification! Science requires us to observe (We see a face on Mars!) then it requires us to consider the likelyhood that this observation is a meaningful thing - (What are the odds that there is really an artificial construct on another planet? What are the odds that this is just a "cloud bunny"?) - if we conclude that the odds are good enough that there is something really going on - we investigate (we move a Mars observation satellite over the feature and we take a much better photo) - when we find we were wrong, we give it up. We don't go on and on banging on about the same thing. There are much more interesting things to do with our big, clever brains.

SteveBaker (talk) 02:31, 5 September 2008 (UTC)

Thankyou Steve, I appreciate your detailed response. And I am also quite interested these “cloud bunnies” you speak of :p . But in all seriousness going back to my earlier question: (Now I am not asking this as some sort of conspiracy nut as there could be a valid answer) why would it appear that NASA has airbrushed photos of mars’ surface? Going through many pictures including the more recent ones I have come across, i have found a lot of them which appear to have been blurred in specific areas. 203.202.144.223 (talk) 02:56, 5 September 2008 (UTC)

Give me an example. It's hard to argue without being able to see the image you're talking about. Note that NASA's imaging folks are REALLY good. If they wanted to hide something - they'd do a bang-up undetectable photoshop job and you'd never know you'd been fooled. Heck - I can do that easily enough. Look at this photo: [1] - it looks OK - right? Well, in reality, the cute puppy on the right had fought like crazy to avoid being photographed looking cute and had scratched my arm so badly I was bleeding from two 3" long cuts. Two minutes with a good image editor - and you'd NEVER know. So why "obviously" airbrush something and arouse suspicion? But show me the photo. SteveBaker (talk) 04:15, 5 September 2008 (UTC)

Example will be on it's way as soon as i get home from work. Damn you restricted internet access!! 203.202.144.223 (talk) 04:53, 5 September 2008 (UTC)

One reason I know of off-hand is that NASA will typically composite together several photos from a spacecraft in orbit. Because the planet is curved and the picture is flat - the photos don't quite line up properly. Also, one photo may be taken several orbits after the other - and the planet rotated in the meantime - so the sun moved a bit in the local sky and shadows moved a bit. The quick/cheesy way to fix that is to blend together the two images along the seam. The slight mismatch shows up as a blur. It's worse where four photos meet at a corner - so that could explain some blurry patches. You can see this happen in places in Google Maps also. However, there may be other reasons...lets' examine an actual 'suspect' photo. SteveBaker (talk) 05:36, 5 September 2008 (UTC)

check these out: LINK ---> [2]

LINK ---> [3] —Preceding unsigned comment added by 61.68.212.191 (talk) 09:15, 5 September 2008 (UTC)

Wow, it's sooo clearly an alien civilization, and not just a bunch of rocks. :-P I mean seriously. This some stretch of the freakin' imagination. --98.217.8.46 (talk) 11:54, 5 September 2008 (UTC)

The pale crater is simple jpg or digital artefacts from the way the pictures are taken the colour depth is not very high and so you end up by pixles which have a different colour than the next one so you se squares, which are no houses, but look like houses for people who have no knowledge on ditigital images. ---Stone (talk) 13:05, 5 September 2008 (UTC)

The hires video from the samples introduced into the TEGA instrument on the other video is great!! I taked to a scientist working on the project and he said that they had great pain because they where not able to get the sticky mars soil through that screen. This is a test of the groundsupport equipment filmed with a camera held next to the robotic arm. The pictures the robotic arm camera is able to take I have seen for myself here in the house and they are black and white and not that reolution at all. There is no camera on mars capable to make avideo like that. Keller the PI of the RAC would have like to have one, but he has not! So the NASA has no such hires videos at all!--Stone (talk) 13:05, 5 September 2008 (UTC)

The thing I find sad about these kinds of conspiracy theorists (and YE creationists, too), is that there is so much *real* wonder and beauty in the natural world, and they ignore it all to focus on these wobbly figments. I mean, there are shrimp that shoot fish with sonic pistols, and these guys are still nattering on about the moon landing 40 years ago! We should pass a law that anyone who has actually walked on the moon can punch these guys in the face whenever they like. --Sean 14:58, 5 September 2008 (UTC)

So - the moron in the video spends FIVE MINUTES to impart ONE URL (click here - then click here - then click here...OH FOR CHRISSAKES! Just tell me the URL already!). That guy is surely fond of his own voice. Then he takes the image and boosts gain until the underlying JPEG artifacts are visible and spends another FIVE MINUTES pontificating about the amazing "roads" and "buildings" he can see. He's looking at regular shaped features in the lowest couple of bits of an approximated image. Here are some ground-rules:

• Rule 1: Don't EVER do image analysis on JPG images - or images that have EVER been stored in JPG format. You need the original TIFF images that were never compressed with a lossy algorithm. In order to save space, the JPEG algorithm discards information that the un-assisted human eye can't resolve. It approximates colors and introduces "blocky" structure in the image. When you view it at normal resolution and normal brightness on a typical display - you don't really notice the errors it introduces - so it's a great way to make porn take up less space. When it matters - YOU DON'T USE JPEG! When you start messing with the brightness, contrast, zoom or anything else, you'll expose data that was deleted by JPEG in order to save space - and untrained idiots like that moron in the video will start to see...whatever they want to see. The joke is that they're looking at deleted data!

• Rule 2: Any image feature that is aligned with the raster pattern of the image is highly suspect - maybe a camera issue - maybe a compression issue. Features that aren't aligned with the raster are much more likely to be "real".

• Rule 3: Serious experts don't post shakey camera-pointed-at-CRT videos to You Tube. They write papers and present them clearly on nicely formatted web pages. People who are fond of their own voices spend five minutes making themselves sound like experts when in reality they are too dumb to read off the image's URL off the goddamn screen!

Please - don't waste our time with this kind of crap.

SteveBaker (talk) 15:38, 5 September 2008 (UTC)

Metric System

why united states has been slow in adopting the metric system? —Preceding unsigned comment added by Christianlazaro (talk • contribs) 03:41, 5 September 2008 (UTC)

Mostly I think it's a lack of incentive. It's an expensive process. The UK more or less did it - but it took 40 years and things were very messy along the way. It's not just a matter of saying "Now switch over!". Consider just one industry - house-building - you have things like the sizes of wood from which houses are made is a "two by four" - two inches by four inches. But you call that a 5cm x 10cm - then you have an error - it's really 5.08cm x 10.16cm. But having 5.08x10.16cm wood in all of your stores isn't REALLY converting to the metric system - it's just calling things by different names. But you can't suddenly start have sawmills start selling "true" 5cmx10cm wood because it won't fit the door frames and metal tie pieces and so forth - the entire building industry would have to redesign absolutely every component - from wood to nails and screws, pipes, tools, everything! Worse still, 2x4's aren't REALLY 2" x 4" - they start out life as that - but are actually smaller when they are planed smooth. So you have an entire industry based around some rather arbitary sized thing. You can't turn that around overnight because people would still need the old-style sizes in order to repair existing structures. Doors have to fit into door frames. You couldn't expect stores to stock twice as much stuff - half metric and half old-style.

Things go deeper than that. In medicine the Americans use "grains" as their unit of weight for pills and such. The abbreviation for "grain" is "g" - which is the same as "gram"...which is the traditional unit for drugs in the metric world. Now you have to administer a change-over period in which tens of thousands of patients are at terrible risk of being over-dosed or under-dosed.

It's VERY tough. The UK only did it because the rest of the Europeans had already done it - and joining the European community was the way ahead. The US have no such problem.

SteveBaker (talk) 05:18, 5 September 2008 (UTC)

See Metrication in the United States. Metrication in the UK is far from complete; see Metrication in the United Kingdom.--Shantavira|^{feed me} 07:45, 5 September 2008 (UTC)

Technically, the entire U.S. systems is based on the metric system, anyway -- it's just that the ordinary person doesn't know and doesn't care.

The U.S. is a large country; its two largest neighbors, Canada and Mexico, have little influence on how things work inside the U.S. And, as far as that goes, in Canada everyday measures like road-sign distance (in kilometers) or gasoline volume (in liters) have only been metric for 30 years.

As with Canada, where there was also great resistance to the switch, the U.S. will gradually shift.

This is an example of how technological innovation works: it's easier to change when you're not dragging a whole lot of infrastructure. In 1955, nearly 83% of Swedes opposed the idea of a switch from driving on the left to driving on the right, though the change did take place on Sept. 3, 1967 (happy belated anniversary, Dagen H). --- OtherDave (talk) 10:50, 5 September 2008 (UTC)

I can't begin to imagine how bad that must have been - if you drive a car on the side of the road for which it was not designed - then overtaking on a two- or three-lane road becomes a lethally dangerous activity. I've driven my (British) right-hand drive car in France - and I have a right-hand drive car here in Texas too (although I don't drive it on the roads much) so I've done this a bunch of times. Overtaking is a really dangerous thing because you have to pull all the way out into the oncoming traffic's lane before you can see what's coming. Even on a multilane road, pulling out from behind a big truck is dangerous if there is a vehicle in the outside lane is going really slowly for some reason. The Swedes must have known this going into it - but I wonder how many people died for that change before the majority of old "wrong side" cars were finally off the roads?

One problem with metrication is that you've got to start educating people into the metric system from way before you start using it. In the UK, I was in the first group of kids to be taught both systems in parallel - that would have been in the early 1960's - so the education process started a good 10 years before the switch began...and the switch is still going on today! More confusing still - we Brit's also changed our currency from it's old mixture of base-12 and base-20 counting to a decimal system around the same time. That wasn't such a horrible mess though - the switch was actually completed a few years ahead of schedule.

As our article says - just the cost of replacing two million road signs (it would be a hell of a lot more than that here in the USA) is frightening. It's not just the cost of making the signs - you have the cost of installing them - and the difficulty of finding them all! Since existing signs typically round distances to the nearest quarter mile for junctions and to the nearest mile for longer distances - you can't simply convert the miles indicated on the old sign into kilometers and round off the result - because the sum of the two round-off errors could add up to a more-than-1km error in the finished sign. You'd have to go out there and re-measure the distances...and in some cases, reposition the signs pole/gantry. You could easily spend several billions of dollars on that alone. SteveBaker (talk) 11:39, 5 September 2008 (UTC)

For what it's worth, according to Dagen H, most Swedes had left-hand drive cars before the switch, which did cause more accidents, and that was one of the arguments for the switch. I suppose there would be at least minor health and safety benefits to having a single system of units in use throughout the world. It would have saved the Mars Climate Orbiter. :-( -- BenRG (talk) 14:59, 5 September 2008 (UTC)

Just to clarify something SteveBaker brought up in his first reply. We have 2x4's in Canada and that's what we call them. We've never "converted" them to anything else. In a way, building materials like that are the easiest to change because the 2" by 4" is unreal (to the end user) to begin with. Canadians call them 2x4s, we just don't call them 2 inches by 4 inches and the problem goes away. I don't think anyone suggests that switching to metric would be a simple thing for the US, but many of the concerns I've read are more hand-wringing than anything else. Afraid grams and grains might be confused? Then do what we did and use milligrams instead of grams. Don't want to remeasure all your roadways? Then don't and just have them precise (1.7km to next exit) and relocate them later if you really want to. Matt Deres (talk) 12:54, 5 September 2008 (UTC)

To clarify further, a 2x4 isn't 2 in. by 4 in. anyway, at least not when you buy it. Dimensional lumber says it is actually approximately 1+1⁄2 in × 3+1⁄2 in (38 mm × 89 mm) "due to planing and shrinkage as the board is dried." -- 128.104.112.147 (talk) 19:21, 5 September 2008 (UTC) Whoops - just noticed Steve already said that.

Just so we're clear, the UK metrification-process is a lesson in how not to metrify. We measure distance in miles (there was no big switch over of signs), sell petrol in litres, but measure fuel economy in miles per gallon. (As with everything, we have to give the metric equivalent as well, but no one could tell you whether, for example, 10km/litre was good or bad. I certainly couldn't. We also have our own 'british' gallon which 90% of people couldn't convert to a US-one. Or litres for that matter). We measure ourselves in pounds (and stone) but the doctor (and our gym) will ask for our weight in Kg.Similarly, i conducted my whole education in metric (up to and including a maths degree), but couldn't tell you intuitively how tall someone was without using imperial. I would love nothing better than to go fully metric but it just won't happen until a couple more generations. Maybe as americans are generally less parochial and twee they might find it easier adapting. 82.22.4.63 (talk) 17:08, 5 September 2008 (UTC)

Thanks for the clarification; I'm laughing at the notion of gas sold by the liter but used as mpg. I know that Canada used the imperial gallon, a source of endless confusion to Americans even in pre-metric days (along with the strange-colored money and that peculiar letter at the end of the alphabet). For most people, the late Thomas Gilbert thought that learning conversion math was pointless. He developed mnemonics -- e.g., for the temperature outside -- "20 is plenty; 25, swim and dive" -- because in that setting, you just want do know if you need a coat (or gloves, or a swimsuit). --- 22:26, 5 September 2008 (UTC) —Preceding unsigned comment added by OtherDave (talk • contribs)

Replying to SteveBaker's first reply: I'm surprised at you, Steve. You say a 2 x 4 is "really 5.08cm x 10.16cm". NO IT IS NOT! That is an elementary error which scientifically illiterate people often make, but I didn't expect to see you introducing spurious accuracy. 2" x 4" is 5cm x 10cm. 5.08cm x 10.16cm is the equivalent of 2.00" x 4.00". I might just about accept millimetre accuracy for wood, but not .1mm. (In fact, for some reason we get 47mm x 100m - see for example [4]. --ColinFine (talk) 22:00, 8 September 2008 (UTC)

100m? I think that you mean 100mm. Axl ¤ [Talk] 19:53, 11 September 2008 (UTC)

Why do celestial bodies spin and/or move in a circular motion?

Planets, suns, even entire galaxies all spin and/or move in a circle, and never stop. Why is this? What is causing this momentum? Stranger still,- all tiny bodies (atoms, electrons, etc.) seem to have this quality. Why only the very small and the very big? Now technically an electron doesn't revolve around the nucleus, but it is a useful way of thinking about it, and it's close eneough to make my point here. Anyways, it seems odd that here at our medium mass perspective nothing seems to spin on its own.Hey, I'm Just Curious (talk) 04:09, 5 September 2008 (UTC)

Well, technically, they move in ellipses - not necessarily circles. But the reason is this: If there is no friction and no air resistance then there is nothing to stop the object from moving (any object - not just suns and moons and such). Newtons' laws of motion say that if there are no forces acting on an object, it'll travel in a straight line at constant speed forever. Here on earth, it's just about impossible to get rid of the friction and air resistance - so we tend to have the "gut feel" that objects ought to slow down and stop eventually - but that's not how the universe works. So that's why they keep moving forever.

Why they travel in elliptical/circular orbits is because of gravity. Throw a rock in a dead straight line towards the horizon and it'll start maybe four feet off the ground and arc downwards in a parabola and hit the ground a few feet in front of you. Throw it a bit harder - and it'll go further forwards before it hits the ground. Now - the earth is curved - so if you throw the object REALLY hard (actually a lot harder than you could ever really throw it) - it would go so far forwards that by the time it had fallen four feet, the earth would have curved away beneath it by MORE than four feet. Instead of getting closer to the ground, it would shoot off - getting higher and higher above the ground until eventually, it ends up in space. If you throw it at EXACTLY the right speed, the rate at which it falls would EXACTLY match the rate at which the curvature of the earth causes the ground to fall away beneath it. So in the time it falls 4 feet - it would have travelled so far towards the horizon that the ground was exactly four feet lower - when it falls four more feet - the ground fell away four feet more than that. It would NEVER hit the ground! If there were no air resistance - it would "fall" around the earth forever travelling in a perfect circle. That's an "orbit". So the moon (for example) is just like your rock - it's travelling so fast around the earth that it falls exactly fast enough to avoid hurtling off into space and to avoid hitting the earth. The exact same thing happens as the earth goes around the sun - or the sun goes around the galactic core. So this is how you get perfectly circular orbits.

What happens in space if the object is going just a little bit too slow to stay up in a circular orbit? Well, that's the kind of thing that happens with comets. They aren't going quite fast enough to stay in a perfect circle - so they start to fall closer to the sun. But as they fall for so long (years!) they gradually speed up - and when they get going fast enough, they are going too fast to stay in a circular orbit - so they swing around the sun and shoot off outwards again. Now the sun's gravity is slowing them down - so they go slower and slower until they start falling back towards the sun. They keep this up pretty much forever - orbiting in huge ellipses.

The idea that electrons are little "planets" orbiting the atoms nucleus "sun" is flat out WRONG - it was thought to be true a hundred years ago - and it was (lamentably) still taught in schools in Texas as recently as a couple of years ago - but it's WRONG! So forget that. An electron is a tough thing to pin down - you never really know exactly where it is because in some sense, it isn't in just one place. There is a "probability cloud" - imagine a fuzzy ball of "maybe there is an electron here"-ness surrounding the nucleus. Hence there is no similarity and the question can be "un-asked" rather than answered.

The reason things at "human scale" don't ever seem to keep moving forever is simply that we live in an environment that's full of gas and rough surfaces. Friction and air resistance are absolutely everywhere humans live - so nothing seems to be obeying Newton's laws (they are - but the friction and air resistance apply forces to them). But the guys in the International Space Station are only too familiar with things that move essentially forever. Their home up there is doing exactly that. (Although there is still a teeny-tiny amount of air up there at 300 miles above the earth - so there is still a teeny-tiny bit of air resistance and eventually it would fall back to earth if we left it alone. Hence, each passing Space Shuttle or Russian resupply ship gives it a bit of a nudge to keep it going - and it has some small engines of it's own that could be used for the same thing.

If we were peculiar aliens who lived in deep space without need for air - we'd be surprised that on Earth everything slows down and stops.

SteveBaker (talk) 04:32, 5 September 2008 (UTC)

Pump Stalling Phenomenon

What is the pump stalling phenomenon in case of centrifugal pumps as well as positive displacement pumps?--Ashish V. Kulkarni 05:40, 5 September 2008 (UTC) 05:11, 5 September 2008 (UTC) —Preceding unsigned comment added by Ashishkulk (talk • contribs) 04:55, 5 September 2008 (UTC)

There are two ways that a pump can stall. Assuming a pumping a liquid:

1. if the input is restricted enough the reduced pressure inside the pump will cause cavitation;
2. if the output is blocked, a positive displacement pump will stop. Saintrain (talk) 13:34, 5 September 2008 (UTC)

A positive displacement pump should always have a relief valve in the output ahead of wherever a valve could restrict flow, to prevent breaking the pump or bursting a pipe. Positive displacement usually means the liquid flows or something breaks, beyond merely stalling.Edison (talk) 15:00, 5 September 2008 (UTC)

Cavitation can also occur when you are using the pump at the top of a pipe to pull liquid up too great a vertical height - the maximum height you can pump water that way is about 32 feet for example. Similarly - the output doesn't have to be blocked (even partially) to stall the pump - there could simply be too much output pressure due to the height the liquid has to be pumped. SteveBaker (talk) 12:32, 6 September 2008 (UTC)

sound waves

1. Strike one of the tuning forks with a rubber mallet or the bottom of a rubber soled shoe. Do not hit the tuning fork on a hard surface, doing so, may damage the tuning fork. Listen to the sound. Now press a button on the telephone and listen to the sound generated through the earpiece. Which sound do you think is more complex? Explain your answer. 2. Compared to the tuning fork and the telephone dialer, is the sound of a person humming, a simple or a complex sound. 3. Try pressing the buttons on the telephone dialer. Can you observe any order to the tones? Does the pitch get higher or lower for larger numbers, or does it seem to be random. 4. How do you think the phone company recognizes the numbers that you dial? —Preceding unsigned comment added by 124.43.195.66 (talk) 05:03, 5 September 2008 (UTC)

Please do your own homework. However, you might want to review harmonics. --Kjoonlee 05:09, 5 September 2008 (UTC)

You can answer this question yourself by following the instructions given to you by your lab (i.e. the instructions you give us). The question is asking for your opinions and observations, so there are actually no wrong answers to these questions if you actually follow through with the directions. For future reference, we will not do your HW for you here per policy, but you can at least try to disguise your assignments with a little more guile in the future. --Shaggorama (talk) 05:12, 5 September 2008 (UTC)

Actually, Touchtone or Telephone keypad should be consulted as well as harmonics. But in essence: tuning fork: one pitch, sine-wave with few overtones (i.e. simple waveform); human voice: one pitch, complex overtones; Touch-tone phone keypad: two pitches, each with a simple waveform. - Nunh-huh 06:06, 5 September 2008 (UTC)

My god. You took the time to type out verbatim your assignment. And now you are waiting with baited breath for answers from the internet. If you had just done the assignment as it tells you to you'd be done by now. You get an epic fail. --98.217.8.46 (talk) 13:02, 5 September 2008 (UTC)

"Baited breath" - what are you trying to catch? ;) Franamax (talk) 07:09, 6 September 2008 (UTC)

At least link to the explanation of the correct spelling. :P — BRIAN0918 • 2008-09-06 18:02Z

If you really don't trust your ears then record the sounds into your computer and analyze the waveforms with Praat. It should be easy to tell which are more complex, but then again it should be easy enough by ear anyway. - Lambajan 02:51, 8 September 2008 (UTC)

fatigue

comparison of stress at fillet radius and bending stress at uniform sections —Preceding unsigned comment added by 196.21.39.11 (talk) 08:09, 5 September 2008 (UTC)

There are people here. People need to be talked to in complete sentences. Can you please make some effort in that direction? You don't want to waste this resource by sending them on the wrong path, do you?. --Ayacop (talk) 08:51, 5 September 2008 (UTC)

Our articles on fatigue (engineering), fillet (mechanics) and stress concentration might help you, but, as Ayacop says, you need to ask a clearer and more specific question if you want more pertinent help. Gandalf61 (talk) 09:36, 5 September 2008 (UTC)

Not to pile on you here, but seriously, asking "questions" like this is pretty much ridiculous. No one can even properly figure out what you're talking about, much less what you want to know. And, unfortunately, a lot of people do this. Just asking an actual question would be a big help, and providing just a tiny bit of context would go a long way -- and by that I mean that you're going to get a lot more and better answers when people don't feel like pounding a nail into their forehead when they see yet another more or less incomprehensible post. -- Captain Disdain (talk) 11:01, 5 September 2008 (UTC)

If you mean making stress calculations for weldments using a technique similar to the standard method for uniform sections, take a look at this page. Note thought that these are calculations for stress, not fatigue. Fatigue is the result of repeated applications of stress, so you don't get an answer measured in "lbs per sq.in." or anything like that. Franamax (talk) 07:05, 6 September 2008 (UTC)

matchwood

What timber are matches most commonly made from? —Preceding unsigned comment added by 143.238.144.179 (talk) 10:51, 5 September 2008 (UTC)

Mainly aspen and white pine. Axl (talk) 12:02, 5 September 2008 (UTC)

Remember it only takes 1 tree to make a thousand matches, but it only takes one match to burn a thousand trees... 194.221.133.226 (talk) 12:43, 5 September 2008 (UTC)

For those who are confused by the response... 81.174.226.229 (talk) 13:01, 5 September 2008 (UTC)

If someone is getting only one thousand matches out of a tree, either they are cutting baby trees or they have an incredibly wasteful cutting process. Wanderer57 (talk) 17:34, 5 September 2008 (UTC)

I'd say around 5000. JessicaThunderbolt 19:05, 5 September 2008 (UTC)

There is a long tradition in both western and other cultures of using the names of specific large numbers (like "a thousand") to metaphorically refer to an indeterminately large amount. (e.g. when the Nazis referred to "the Thousand Year Reich", they weren't intending to give back Poland come September 1, 2939.) I'd link to an article, but we don't seem to have "Metaphorical use of large numbers", and the articles "large numbers" and "thousand" don't show anything promising. -- 128.104.112.147 (talk) 19:15, 5 September 2008 (UTC)

If I've heard that once, I've heard it a thousand times. --- OtherDave (talk) 02:23, 6 September 2008 (UTC)

You know, a picture is worth a thousand words... Medical geneticist (talk) 21:52, 10 September 2008 (UTC)

Origin of life

What are the probabilites that universal common descent isn't actually true, and that life on Earth is in fact polyphyletic? Couldn't it be that life arose a few times on this planet, and that the basic similarities between living beings are just convergent adaptations to the same selective pressures? Leptictidium (mt) 12:06, 5 September 2008 (UTC)

Pretty unlikely, if you look at DNA and RNA codes there is ample opportunity for variations, but only small variations occur. And the basic biochemistry seems to be the same for all organisms, there is no detected radically different pathways around suggesting a different source of genomes. If you take a look at the book of Genesis in the bible you can see there were three special acts of creation, with the universe, sea creatures, and humans being the three things created and not made. But in any case you can be pretty sure that human DNA has come from animals. Graeme Bartlett (talk) 12:32, 5 September 2008 (UTC)

You might want to look at abiogenesis you question is discussed ever so briefly here. There are arguments that life is may still originating around volcanic vents at least from the theory I prefer Iron-sulfur world theory(metabolism first). How far this new life gets before more advanced life gets a hold of this proto-life-matter isn't very far. So it is very likely that life started in multiple places, and still is, it just can't out do the life that is already established. This is supported, since, we generally don't see life with proteins and DNA of different Chirality (chemistry) we see homochirality. It is likely that origin sources with different chirality were quickly out competed by sources with a common chirality that could combine traits into a single more advanced system (likely a pre-genetics world). The choice of chirality seems random and there is the possibility that there is a planet of life in the universe that is our molecular mirror, take a look here. A very neat subject that is only studied in a limited way. I hope that helps.--OMCV (talk) 12:33, 5 September 2008 (UTC)

Chances are genetic material was not the first biological matter. See abiogenesis for metabolism first vs genetics first (RNA_world_hypothesis). Amino acids and the resulting proteins are far simpler than nucleic acids acids and their polymers. This makes it more likely that amino acids would form and self replicate before the formation of the more complex coding system for self replicating. An analogy would be: there is machinery that works without software but there it no software that works without machinery. Back to biology, glycine is only C₂H₅NO₂ while adenosine is composed of adenine and a sugar molecule for a grand total of C₁₀H₁₃N₅O₄ before adding phosphates. Sure all the other amino acids are more complex than glycine but its variation at one position. In contrast all nucleosides are made of nucleobase, sugar, and up to three phosphates. This means you need to locate these three pieces before you can make DNA. An inorganic metal center with amino acids as ligands which used available substrate to make more amino acids, a proto-self-propagating-enzyme, was probably the first form of life. As far as the bible is concerned, it is generally not a good source of scientific knowledge even if it has significant spiritual and allegorical knowledge as Augustine of Hippo pointed out very early on.--OMCV (talk) 13:43, 5 September 2008 (UTC)

Yeah, but who would trust a hippo? I wouldn't. --98.217.8.46 (talk) 14:43, 5 September 2008 (UTC)

Your comment is blatantly hippocritical. -- BenRG (talk) 15:04, 5 September 2008 (UTC)

One thing the above comments don't address is that "life" in a basic form might have emerged multiple times on the early Earth only to have the gene pools merge together. Lateral gene transfer, i.e. the transmission of genes between non-descendent organisms, is well-documented at various times in history and among various kinds of bacteria. Many of the hypotheses about what the first life may have consisted of point to organisms with far less stable genetic material and less structured cell membranes, which increases the probablity that if cell-like life arose more than once then the different strains could have exchanged genes. Do enough of that and even independently originating life forms could come to share a common genetic heritage. Dragons flight (talk) 19:31, 5 September 2008 (UTC)

The issue with lateral gene transfer is that in order for organisms to share genetic material they have to have the same type of genetic material. To be the same it means the genetic material has to have the same chirality (chemistry) (in multiple locations) and the same coding system for proteins. Its becomes statistically questionable whether life got all the way to genetics material twice because once would be enough. Once life gets to genetics it becomes a collaborative effort with gene trading galore probably even some amount of advancing or cleaning up of the genetic code. Surely whatever came up with genetics blew everything else out of the water. What I mean by blew them out of the water is that they ate the matter that might have been proto-life (and still do). This all ads up to an explosion of life. All "important" life is likely descended from the system that figured out genetics everything without genetics would be left in their biological dust. If earth was void of life (in theory) it might take a very short amount of time for life to develop here. But the reality is that there is so much life here any new comer "proto-life" gets chewed up by those of us with a foothold. Thanks for the comment, Dragon, I just wanted to expand on it.--OMCV (talk) 20:02, 5 September 2008 (UTC)

You assume they have to be the same, when in fact they merely have to coexist well together. Maybe organisms from your iron-sulfur world met other organisms from an RNA world.  ;-) If one had superior genetic structures and the other had superior metabolic pathways they could complement each other even if initially they had entirely seperate approaches to life. Perhaps it was only later that the connection between genetic material and proteins was made. Its more radical than traditional lateral gene transfer (since in particular we are talking about an era before traditional genes), but it is possible, at least in principle, to imagine that some of the features we see as belonging to all cells today orginiated in independent strains of life. Dragons flight (talk) 20:19, 5 September 2008 (UTC)

I get what your saying; critter (a) developes genetics even though it might not have the best proteins at the time. Critter (b) has better proteins or at least a few the first critter doesn't. As long as they don't kill each other it likely that critter (a) and (b) will exchange chemical systems. I'm no biochemist I don't know if the enzyme or system exists now, but surely there has been a mechanism to produce genetic material from proteins. Its just the microscopic reverse of todays standard direction of making proteins from DNA. If critter (a) had this mechanism it could run around finding all the valuable proteins and record their sequence for posterity. Very good point and neat stuff.--OMCV (talk) 21:18, 5 September 2008 (UTC)

Inducing hyperthyroidism to lose weight?

Are there examples of people trying to ramp up thyroid hormone production (or taking thyroid hormone pills) in order to increase the basal metabolic rate to lose weight? How successful is this approach, or does it likewise increase hunger and cause you to eat more? (not for school) — BRIAN0918 • 2008-09-05 15:25Z

Yes, there are examples. Indeed it's a classic MRCP question. It does cause weight loss. However there are several harmful effects of excessive thyroid hormone levels. After ceasing levothyroxine, the person regains weight. Many of these people have co-existent psychiatric illness that may complicate the clinical picture. Axl (talk) 16:54, 5 September 2008 (UTC)

Interesting. So in order to maintain the weight loss, you would have to continue taking the pills, or exercise more (since apparently eating less simply reduces BMR). When you mention psychiatric illness, are you implying that the excess levels caused mental problems, or simply that the example you cited involved people with mental problems, reducing the certainty of the amount of weight loss caused by thyroxine? — BRIAN0918 • 2008-09-05 16:58Z

According to de:Thyroxin (but without refs), other problems are that increase of metabolic rate can be completely revoked by simply eating more, so you'll be probably hungry (and if that is okay with you then why not simply eat less beforehand?). Also, insulin resistance is increased, the heart and circulatory system is stressed, and for women during menopause osteoporosis risk increases. Finally, hormone and TSH values should be checked constantly if you want to do it right. --Ayacop (talk) 17:11, 5 September 2008 (UTC)

Regarding psychiatric illness, the people who abuse levothyroxine in this way usually have an eating disorder (anorexia nervosa or bulimia nervosa) before commencing levothyroxine. Axl (talk) 17:19, 5 September 2008 (UTC)

And hair loss. Let's not forget about hair loss.  :) OK maybe just with a thyroid storm. OrangeMarlin ^{Talk• Contributions} 23:34, 5 September 2008 (UTC)

It's been used...and it's not a good option. TH regulates many different processes in the body and there can be severe cardiac and bone issues, for example, in those out-of-balance. Here's a case of periodic paralysis from abusing thyroxine. — Scientizzle 23:51, 5 September 2008 (UTC)

Yes, there are many examples as cited above. Thyroid supplementation certainly can produce weight loss, but as mentioned above it's not sustainable upon discontinuation of levothyroxine. The reason this is not tried on a wide scale is the cardiotoxicity associated with thyroid hormones. Thyroid hormones sensitize the sympathetic nervous system, producing tachycardia and elevated systolic blood pressure that taxes the heart and can lead to cardiac arrhythmias and heart failure. Not the best approach for weight loss. --David Iberri (talk) 21:25, 8 September 2008 (UTC)

Heres the deal with using thyroid hormones.... Yes they do work, and using T3 (cytomel) is much better then T4 (synthroid) because T3 is the active hormone, T4 is just converted to T3. A few major problems exist: 1. Your body decreases or stops making thyroid hormones when you supplement them, when you get off, its slow to raise its levels back up and during this time period is when most people regain the weight. 2. It doesn't burn fat exclusively, it also burns muscle. You want to preserve muscle because muscle burns calories, you will be burning less calories if you lose muscle, this is part of the reason most people cannot keep the weight off from dieting (also because they go back to their old diet and stop exercising). 3. Its bad for your heart, your thyroid levels being high are bad for your heart and im sure a lot of other things. You will be very uncomfortable and sweat a lot if your thyroid levels are very high.

Many bodybuilders use it and you can find tons of information about it on the steroid forums online. Bodybuilders use it with steroids usually to preserve muscle. There was some talk about how cytomel or HCG could be used to restore thyroid function in a week, but I'm not too sure of it.

americium in smoke detectors

so, how much americium is exactly in an average smoke detector? I know the article says 'less than a milligram' but that's trivially true with a cost of ~$160/mg. --Ayacop (talk) 15:27, 5 September 2008 (UTC)

This says 0.2mg of Americium Dioxide. Fribbler (talk) 15:34, 5 September 2008 (UTC)

Ah, thanks. That's still ~$30/detector but you can get them for much less. So either the file or the price is wrong. --Ayacop (talk) 15:36, 5 September 2008 (UTC)

Google thinks that about $1500 will buy you a gram of americium-241 dioxide. Algebraist 15:51, 5 September 2008 (UTC)

So we're down to 30 cents per detector. — BRIAN0918 • 2008-09-05 16:00Z

If you took the price from [5], note that the $160/mg price is for the isotope Americium-243, whereas ionisation smoke detectors contain Americium-241. Gandalf61 (talk) 15:52, 5 September 2008 (UTC)

Lower cost if you buy in bulk? — BRIAN0918 • 2008-09-05 15:58Z

Certainly too. All my questions have been answered. Thanks again. --Ayacop (talk) 16:50, 5 September 2008 (UTC)

The article says that Americium-241 is fissile with a critical mass of 60 kg (bare, unreflected sphere). Does that mean that with a mere 300,000,000 smoke detectors you'd have enough of the stuff for a nuke? Someone alert the media—this could be the next big thing to get worried about! ;-) --98.217.8.46 (talk) 19:34, 5 September 2008 (UTC)

Radioactive boy scout. Dragons flight (talk) 19:42, 5 September 2008 (UTC)

Right, but even he never tried to make a pure-Americium weapon... --98.217.8.46 (talk) 20:43, 5 September 2008 (UTC)

Monkey wedding

What is the reason of this wedding? Does this serve any purpose? Otolemur crassicaudatus (talk) 15:46, 5 September 2008 (UTC)

It serves about the same amount of purpose as spamming a bunch of nude images on FPC, or linking to this story on RD/S, I reckon. — BRIAN0918 • 2008-09-05 16:17Z

The caption answers your question: "The widlife park organized the wedding in the hope of attracting more visitors, local media reported." Thats about it. Fribbler (talk) 15:51, 5 September 2008 (UTC)

Withdraw post. I should have asked this in Wikipedia:Reference desk/Miscellaneous or Wikipedia:Reference desk/Entertainment, My mistake I asked it in science ref desk. Otolemur crassicaudatus (talk) 16:43, 5 September 2008 (UTC)

Hmm, so you think you'll get a 'better' answer there? 86.4.187.55 (talk) 19:21, 5 September 2008 (UTC)

Yoghurt phobia

I have a phobia if yoghurt, I cant touch it, have it 2 close to me or anything or I will just freak out or breakdown crying. REcently to try an overcome my fear I tryed touching an unopened 'Activia' yoghurt and I almost had a panic attack, also I got a pot of 'Ben and Jerrys chocolate brownie' frozen yoghurt and put my spoon in, poured all the frozen yoghurt off and put my tongue on the spoon, the day I did that I felt completely sick and couldnt eat anything, and was depressed, for the rest of the day. I am slowly dealing with it, those two occasions were big steps, but I was just wondering if there was a name for this phobia or it was common or regognised? 82.16.111.72 (talk) 20:34, 5 September 2008 (UTC)

You really ought to seek professional advice. Other than that, no, it's not got a fancy Latin name and it is not common or recognized as a specific phobia. If it did have a specific name it would probably be Iogurtophobia or something like that (judging from the Latin Wikipedia page for Yoghurt).--98.217.8.46 (talk) 20:41, 5 September 2008 (UTC)

Call it a hunch: but I suspect your condition might have a lot to do with being a bored thirteen year old without much time on his hands who is looking for lulz. Magog the Ogre (talk) 21:27, 5 September 2008 (UTC)

We have a list of phobias, but "fear of yoghurt" is not on that list. On the other hand, it is very common for people to have an aversion to a particular food or ingredient to the extent that they cannot even bear the smell or the sight of it. Gandalf61 (talk) 08:55, 6 September 2008 (UTC)

As noted in List of phobias: "In many cases people have coined these words as neologisms, and only a few of them occur in the medical literature. In many cases, the naming of phobias has become a word game,"...and also..."Note that no things, substances, or even concepts exist which someone, somewhere may not fear, sometimes irrationally so". So even if you found a word for "irrational fear of yoghurt", it's likely that the word would be a totally irrelevent neologism that no practicing doctor would know or use. If one had to tie this down, it would either be a highly specific form of Cibophobia (fear of food) or, perhaps more likely Bacillophobia, (fear of bacteria) - which is the likely reason this person fears strawberry yoghurt but not (say) strawberry mousse - because, despite their near-identical ingredients and near-identical packaging, yoghurt is the result of a bacterial fermentation. If this is the case, why is our OP not afraid of products like beer and bread - which are made in similar ways? SteveBaker (talk) 18:36, 6 September 2008 (UTC)

Becuase it's an irrational fear, why what'd you think? – b_jonas 21:20, 6 September 2008 (UTC)

How is yoghurt different from beer and bread? Only yoghurt contains living microorganisms. - Nunh-huh 01:09, 7 September 2008 (UTC)

Not all yoghurt. The fancy "Activia" stuff does - but a typical flavored yoghurt with bits of fruit in it doesn't. SteveBaker (talk) 18:59, 7 September 2008 (UTC)

Depends on the brand - there are lots of yoghurts with active cultures, not just Activia. This includes those with bits of fruit, and some frozen yoghurts. Yoghurts without active cultures have been heat treated to kill the organisms used to make it, in order to prolong their shelf-life. The only way to be certain if you're getting living or dead organisms in your yoghurt is to read the label. - Nunh-huh 18:37, 9 September 2008 (UTC)

Cyst or what?

I had what my dermatologist called a cyst under my skin, and I just popped it out. It's a small black capsule and I was just wondering what it is exactly. Coolotter88 (talk) 21:12, 5 September 2008 (UTC)

Have you read Cyst? --Tango (talk) 22:03, 5 September 2008 (UTC)

Yes, I didn't find any help there :( Coolotter88 (talk) 22:18, 5 September 2008 (UTC)

I'm not going to do it myself, but it's very, very likely that this question is going to be removed. The only person who can tell you what it is is someone who can look at it with their own two eyes and give you a professional answer.--El aprendelenguas (talk) 22:58, 5 September 2008 (UTC)

It sounds like the OP has already treated the condition themselves, so this isn't really a request for medical advice. Idle curiosity about medical matters is an appropriate topic for this desk. --Tango (talk) 23:26, 5 September 2008 (UTC)

That is correct, I'm not asking for medical advice, I'm just curious what this thing is that came out of my body. It is a capsule about 1-2 millimeters long. It is fairly hard as I can't crack it with my nail (okay, we're not comparing gemstones here, so yeah). Coolotter88 (talk) 23:31, 5 September 2008 (UTC)

What Tango is saying is that we don't do medical diagnostics here. We leave that to House (TV series) and ER (TV series), both fine TV shows. Really, bring it to your physician. OrangeMarlin ^{Talk• Contributions} 23:33, 5 September 2008 (UTC)

Another way to put it so the OP may possibly understand... Claiming "It's a small black capsule" does not narrow it down to one or two things. It narrows it down to a few thousand (if not more) things. Do you honestly believe that getting a list of a few thousand things that appear to be hard black capsules will provide you any help in any way? Of course not. Take it to a doctor and get a real answer. -- kainaw™ 23:54, 5 September 2008 (UTC)

Have you been hanging out in the jungles of South America recently? -- 71.125.61.216 (talk) 02:38, 6 September 2008 (UTC)

Did it look like these little capsules[6] sometimes found under the skin? Edison (talk) 03:55, 6 September 2008 (UTC)

Some more information like what age are you and where was the cyst would be helpful. However I am going to suggest the most likely possibility. It is a dried up sebaceous cyst (aka comedo) that has encapsulated and separated itself from the surrounding tissue. It is hard because all the oily cheesy secretion and skin flakes have concreted together. I'd be interested to hear what the 'few thousand' other possibilities might be. Richard Avery (talk) 10:28, 6 September 2008 (UTC)

Thank you, that's probably what it is, I was just looking at sebaceous cyst and I had asked my mom what it was (she used to be a doctor). She said the most likely thing was that it was a dried up cyst. That's a good enough answer for me. Coolotter88 (talk) 11:20, 6 September 2008 (UTC)

Need a 3D anatomy applet

Dear Wikipedians:

I'm taking a gross anatomy course right now and am in desperate need of a 3D human anatomy applet that could be run from the browser. Any pointers?

Barring that, are there any good 3D human anatomy software out there?

Thanks,

76.65.15.205 (talk) 22:34, 5 September 2008 (UTC)

Would something like the Visible Human Project do? At the bottom of the article are several links to online viewers. SteveBaker (talk) 02:10, 6 September 2008 (UTC)

wow! That's soooo good! thanks a lot steve! 74.12.198.186 (talk) 15:18, 7 September 2008 (UTC)

You don't want to know how they got their data though...it's kinda gross! SteveBaker (talk) 18:55, 7 September 2008 (UTC)