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February 17[edit]

Regarding the article Homogenized Milk and Atherosclerosis[edit]

I have removed this discussion because we are not allowed to give medical advice. All a wikipedia article can give you is general information. For specific situations, you need to see a doctor. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:54, 17 February 2013 (UTC)[reply]

KEF-2013[edit]

This is being reported as the name of the Russian meteor, but the name doesn't seem to follow the patterns discussed in our Astronomical naming conventions article. What system are the Russians using here (and do we need to expand our article)? Rmhermen (talk) 00:40, 17 February 2013 (UTC)[reply]

If any astronomy convention applies, it would be Provisional designation in astronomy, not Astronomical naming conventions. That being said, I don't think that either of those apply to objects within the earth's atmosphere. The Meteoritical Society has some guidelines,[1] but if it is within Russian airspace, I am pretty sure that the Russian Federal Space Agency gets to name it. --Guy Macon (talk) 08:25, 17 February 2013 (UTC)[reply]

Our Astronomical naming conventions article covers provisional naming. But that would yield a name like 2013 C[x]_[x] and meteorite naming will involve the name Chelyabinsk probably. Our articles don't seem to mention national bodies making up their own naming system. Do we know any details? Rmhermen (talk) 14:00, 17 February 2013 (UTC)[reply]

The question is whether astronomical naming conventions apply to non-astronomical phenomena such as meteors and meteorites. What is the IAU designation for the Canyon Diablo meteorite? The Sutter's Mill meteorite? The Sikhote-Alin meteorite? The only meteor or meteorite that I know of that has an IAU designation is 2008 TC3, and that is because it was observed, tracked, and named prior to reaching Earth. --Guy Macon (talk) 14:55, 17 February 2013 (UTC)[reply]

Non-astronomical? Not really. But my question is what system yields a name KEF-2013 and why doesn't Wikipedia seem to know about this system? 17:35, 17 February 2013 (UTC)

I'm very sceptical that anyone really does call this KEF-2013. Our use of that name seem to come from this report, which says Speaking at the Krasnoyarsk Economic Forum, Mr Medvedev called the fallen meteorite in Chelyabinsk "KEF-2013," according to a translation obtained by Newsroom America. I'm suspicious if that site has mistaken the name for the meeting at which Medvedev was speaking - Krasnoyarsk Economic Forum (KEF-2013 / КЭФ-2013) [2] - for a name for the meteor. I note that the Russian Wikipedia article about the meteor does not call it KEF or КЭФ (except for where it parrots that questionable, unsure newsroomamerica ref, as we do). So TL;DR: I don't believe it is called KEF-2013, as I can find no reliable source that it is. -- Finlay McWalterჷTalk 18:49, 17 February 2013 (UTC)[reply]

I should say that I don't think there is anywhere in Russia called "Кзф" (except what I think is a North African restaurant in Yekaterinburg). There's a really minor geoname Кеф in northern Sakhalin, which is nowhere near the meteor's area. -- Finlay McWalterჷTalk 18:58, 17 February 2013 (UTC)[reply]

I have been editting the article, and when I had added the KEF name to the lead I went to look for better reliable science sources, of which there are apparently none in English or Russian. μηδείς (talk) 19:59, 17 February 2013 (UTC)[reply]

Turns out this is a myth with a rather funny explanation after all, see here for what I discovered about the supposed designation. μηδείς (talk) 16:57, 18 February 2013 (UTC)[reply]

Response to the above claim. --Guy Macon (talk) 20:51, 18 February 2013 (UTC)[reply]

Finlay McWalter gives the same explanation I do, but it doesn't appear that Guy Macon is stalking Finlay McWalter, just Medeis. μηδείς (talk) 04:14, 20 February 2013 (UTC)[reply]

Quantum tunneling[edit]

What's the probability that Andy Roddick's fastest serve (155 mph) would tunnel through the net? Also, how fast must he serve in order for the ball to have a non-negligible tunneling probability? (Also, for the sake of the argument, how fast must he serve in order to physically make a hole in the net?) 24.23.196.85 (talk) 06:46, 17 February 2013 (UTC)[reply]

what makes you think there is a speed at which there is non-negligible tunnelling probability at such huge, macro scales? you do know there's a univeral speed limit.... 86.101.32.82 (talk) 08:53, 17 February 2013 (UTC)[reply]

What would happen as that speed limit was approached by a baseball or tennis ball is analyzed here. --Guy Macon (talk) 15:00, 17 February 2013 (UTC)[reply]

In that case, assume that he's playing tennis on the Moon. ;-) (That should also get rid of the quantum zeno effect that Iblis mentioned.) 24.23.196.85 (talk) 04:14, 18 February 2013 (UTC)[reply]

Interesting question! Answering the first question is a bit tricky, as the standard textbook estimates based on particles tunelling through a barrier will greatly overestimate the probability. What happens with the ball is that the constant interactions with the air molecules effectively leads to the state of the ball being measured very frequently, which greatly suppresses the tunneling probability. This is called the quantum zeno effect. Count Iblis (talk) 15:45, 17 February 2013 (UTC)[reply]

Reminds me of an exercise in my physics class where we had to calculate the probability of Santa Claus tunneling into a house. As far as I remember assuming a rectangular potential barrier was considered sufficient then (it was Christmas time so the examiners were kind...). bamse (talk) 20:56, 17 February 2013 (UTC)[reply]

If we can find a RS with a numeric answer for Tunneling Santa it might make a good example of a number that exceeds the range of the Quadruple-precision floating-point format. --Guy Macon (talk) 20:59, 18 February 2013 (UTC)[reply]

(un-indent) OK, another related question: Suppose A-rod makes a "normal" 140-150 mph serve over the net, but Roger Federer returns it with so much top spin that the ball's angular velocity around its own axis reaches a relativistic value. (In real life, of course, the ball would disintegrate long before that point, but assume that for some reason this doesn't happen.) What kinds of weird non-Newtonian effects (if any) can be expected in this sci-fi scenario? 24.23.196.85 (talk) 04:48, 19 February 2013 (UTC)[reply]

Relevance of physics to microbiology.[edit]

What are the relevance of physics to biology? — Preceding unsigned comment added by 196.46.246.49 (talk) 12:31, 17 February 2013 (UTC)[reply]

You might want to start with gravity, acoustics, optics, thermodynamics, motion, aerodynamics, sound, sun, tides, and energy.--Shantavira|^{feed me} 13:55, 17 February 2013 (UTC)[reply]

Also you should know that you, your body is nothing but a combination of chemical elements held together by laws of physics. Your mind is nothing but a manifestation of chemical activities. Simply put, you are nothing but a complex combination of natural elements. There is no difference between you and a rock except that you have signaling and self-sustaining processes known as life. A rock lacks signaling and self-sustaining process. And this very thing called life would have never originated without the laws of physics. The laws of physics enabled you to write this question in the reference desk. --PlanetEditor (talk) 15:55, 17 February 2013 (UTC)[reply]

There's a whole discipline called biophysics. -- 67.40.213.4 (talk) 21:46, 17 February 2013 (UTC)[reply]

3d effect when watching TV while you look through a small hole with one eye[edit]

A long time ago when I got interested in 3D pictures I noticed you get a strange 3 D effect watching a normal t.v. program if one of the eyes is looking through a small hole. The effect is clearly visible when looking at moving objects on the screen. I guess what is going on is that by looing at the screen this way, you mess up the information about the parallax (which should be amost exactly the same for all objects on the screen) slightly, and then the brain uses other information like motion to "correct" the information about the parallax, usually leading to natural 3d effect. I'm not sure about this explanation, though. Count Iblis (talk) 15:39, 17 February 2013 (UTC)[reply]

This sounds like one of a few strange effects that depend on the fact that the response time of the retinal cells is dependent on light intensity. I assume you mean a hole small compared to your iris, in a card or something held close to the eye, thus "stopping down" the light entering the eye. Stronger light produces a faster response. You get an effect similar to what you describe if, if lighting conditions are right, you look at a TV with a sunglass lens (not polaroid type) in front of only one eye. A more surprising (to most people) is trying this with an analog TV tuned to a vacant channel, so that what's on the screen is just snow. The effect of reducing the light intensity to only one eye is a rotating barrel effect - some of the the snow seems to move to the right in front of or behind some of the snow moving in the opposite direction. If (say) your are looking at a scene with objects moveing to the right, and you stop down the right eye, then the right eye image is effectively delayed slightly, which means the object is displaced to the left, giving a false 3D effect. There was a university chap who researched this about 20 years ago. No promises, but if I can remember his name, I'll post some details. Wickwack 121.221.31.66 (talk) 16:08, 17 February 2013 (UTC)[reply]

Is this related to the Pinhole camera effect? Alansplodge (talk) 17:36, 17 February 2013 (UTC)[reply]

That was my thought. Perhaps his vision just needs correction, and a pinhole lens corrects it to the point where his brain can assign depths more accurately than it can with blurry objects. StuRat (talk) 23:36, 17 February 2013 (UTC)[reply]

Certainly technically possible, but not very likely, as he should have noticed poor vision and gone to an optometrist or doctor - what about it Count Iblis? The boffin who investigated the visual effects of stopping down the light to only one eye had the familay name Sala, but I have not tracked down his paper yet. Wickwack 120.145.59.43 (talk) 00:23, 18 February 2013 (UTC)[reply]

The thing is, with gradual visual acuity loss, you don't notice it. Blurry is your normal. This happened to me, and I didn't realize I needed contacts until years later. I was amazed how much clearer things looked. StuRat (talk) 00:30, 18 February 2013 (UTC)[reply]

I remember hearing on a radio programme, years ago, a caller whose teenaged sister was too vain to wear glasses and took to watching television through one of the holes in a Rich tea biscuit. Perhaps she could see it in 3D too - who knows? Alansplodge (talk) 01:17, 18 February 2013 (UTC)[reply]

I've found just closing one eye means any photo or video looks much more 3D, I presume because there only depth information is the same between these and a real scene. How much are you actually seeing with the eye through pinhole here? It wouldn't surprise me if you're having a similar problem. Nil Einne (talk) 02:54, 18 February 2013 (UTC)[reply]

Hmmm... it seems like looking through a pinhole while using a contact lens (-5) produces a distortion effect - letters on the monitor are noticeably displaced toward the edges of the pinhole. I'm not immediately sure why that is. The overall effect is subtle - it doesn't seem like there's a net magnification when superimposing with the other eye, rather, the words in some lines in between don't quite line up, and move very noticeably if it is wiggled. Wnt (talk) 20:11, 18 February 2013 (UTC)[reply]

velocity of meteor[edit]

NASA gives the aphelion of the Russian meteor at about 2.5 AU. Suppose you want to calculate the speed of it when it crosses the Earth's orbit, assuming that the Earth is not there. Can you calculate the difference in potential energy between 1 AU and 2.5 AUs and assume that is converted into kinetic energy? Bubba73 ^{You talkin' to me?} 20:53, 17 February 2013 (UTC)[reply]

Yes, you can, but this gives only a lower bound, since you'd have to add the kinetic energy at aphelion to this to get the total kinetic energy. --Roentgenium111 (talk) 21:24, 17 February 2013 (UTC)[reply]

At aphelion, the kinetic energy would approach zero, right? Bubba73 ^{You talkin' to me?} 00:41, 18 February 2013 (UTC)[reply]

Well, kinetic energy towards or away from the object it's orbiting would be zero, yes. However, it would still have kinetic energy in a direction normal to that, in the orbital plane. StuRat (talk) 01:20, 18 February 2013 (UTC)[reply]

StuRat, energy is a scalar. It doesn't have a direction. Dauto (talk) 19:26, 19 February 2013 (UTC)[reply]

Is there any reason we can't break it down into components as I've done ? For another example, how about rotational kinetic energy versus translational, for the same object ? It certainly would seem useful to divide those up, in some case. StuRat (talk) 06:28, 20 February 2013 (UTC)[reply]

Yes, you are right. But assuming that it had no kinetic energy at aphelion, I get that its velocity should be 32,700 m/s when it reached Earth's orbit, but NASA said that its speed was 18,000 m/s. Bubba73 ^{You talkin' to me?} 01:59, 18 February 2013 (UTC)[reply]

Whoops, that would be the speed relative to the Sun - not the moving Earth. Bubba73 ^{You talkin' to me?} 02:19, 18 February 2013 (UTC)[reply]

Well, this website gives an approximate semi-major axis of 1.66AU and eccentricity of 0.52. That is enough for a better calculation, with a little more work. Bubba73 ^{You talkin' to me?} 02:15, 18 February 2013 (UTC)[reply]

I heard back from the NASA meteor expert, and he says that about 14 of the 18 km/sec speed of the Russian meteor was from its orbit around the Sun - the rest from gravitational attraction from the Earth. Bubba73 ^{You talkin' to me?} 00:08, 19 February 2013 (UTC)[reply]

Resolved

Bubba73 ^{You talkin' to me?} 01:51, 22 February 2013 (UTC)[reply]

Underground bunker effects of the Russian meteoroid?[edit]

Would a underground survivalist type of bunker 2 - 4 meters down with 10 cm concrete walls be affected from the 2013 Russian meteor event in any significant manner ..? Missile bunkers are protected from shock waves by having most interior equipment mounted on springs. Perhaps a meteor ground impact would be different and blast the walls located underground with shock waves much in the same manner that sea waves become larger closer to the beach. I find the behaviour of underground shock waves hard to predict and their behavior when they encounter a sharp density change that perhaps results in a superposition reflection that result in an force from the surrounding ground that cracks the walls. Electron9 (talk) 22:41, 17 February 2013 (UTC)[reply]

An underground bunker is going way too far. Any modern building in a first-world country could have survived the meteor with minimal damage, provided it was built to code. Most of the damage the meteor caused was broken glass, but most glass windows nowadays are shatter-proof. See this discussion above. --140.180.243.51 (talk) 23:17, 17 February 2013 (UTC)[reply]

Do they really use tempered glass in modern windows now? Which is not shatter-proof anyway. I think if you bang it with a hammer really hard, it'll still break. Maybe it might take multiple hits but it's not shatter-proof. I know you didn't mean blast-resistant bulletproof glass, and even a big enough asteroid's shock wave would shatter that. My windows (among others in this part of the first-world) bend and sound like plastic. Is that really glass? Sagittarian Milky Way (talk) 01:40, 18 February 2013 (UTC)[reply]

Glass bends if it's thin enough. It also may be coated with plastic to hold it together, if it does shatter (I think they normally put the plastic layer between the glass panes, though, so it doesn't get scratched up). And you're right that being resistant to point impacts, like bullets, is quite different from being resistant to pressure changes over the entire surface, which you get in blasts. 01:46, 18 February 2013 (UTC)

I dunno, almost everywhere I've lived sounds really plasticky when tapped, like a dull thud. I thought flexible Gorilla Glasses were shelved though for lack of need until the advent of demand for 0.7mm smartphone screens? I found out that my uncle's cheap landlord didn't fix all of the windows (or the bell) by giving one a love tap that shouldn't have been anything close to breaking it, and I made the Fall-Winter 2011 hole. Yay impact resistance! It was an umbrella, so no Cheylabinsk-esque injuries Sagittarian Milky Way (talk) 02:29, 18 February 2013 (UTC)[reply]

It probably sounds "plasticky" because its laminated glass. There's a layer of plastic between both panes of glass, which would certainly alter the sound from plain glass. — The Hand That Feeds You:^Bite 23:01, 19 February 2013 (UTC)[reply]

As I remarked in reply to the original thread, I'm not convinced the OP is correct nor 140. Perhaps it's a requirement where they live, but while I'm unclear precisely what they're referring to, I'm not sure it's a requirement here in New Zealand. Nil Einne (talk) 02:57, 18 February 2013 (UTC)[reply]