Wikipedia:Reference desk/Archives/Science/2012 August 20

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August 20

Looking into the past

Is it possible in theory to look at the a part of the universe as it is now, and use that data to "predict" exactly how it was at a point in the past at a human scale? Could we learn exactly what the Earth was like down the last atom 100 million years ago, for example?--178.167.204.238 (talk) 01:07, 20 August 2012 (UTC)

Absolutely, on a large scale. Just look at any object, like Pluto, and we can tell where it was in it's orbit back potentially billions of years. The same is true of stars and galaxies.

Not at all, on the small scale. We don't know where each atom was 100 million years ago. StuRat (talk) 01:10, 20 August 2012 (UTC)

Well, I understand we don't, but in theory could someone in the future with lots of resources and time gather enough data to work that out, or does something prevent that?--178.167.204.238 (talk) 01:21, 20 August 2012 (UTC)

Entropy and black holes? AFAIK they technicaly don't destroy information, but i'm pretty sure they make it practically irretreivable. Vespine (talk)

(ec x3)See Heisenberg uncertainty. It prevents the type of small scale back tracking you're talking about by preventing you from knowing the exact state of everything at any time, past, present or future. 203.27.72.5 (talk) 01:36, 20 August 2012 (UTC)

(ec)The uncertainty principle makes it impossible to gather that much information. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 01:38, 20 August 2012 (UTC)

This idea is the basis for the slightly-reputable Omega Point theory by Frank J. Tipler. Staecker (talk) 02:33, 20 August 2012 (UTC)

Absolutely not! Forget about the necessary computational power, given no computer in the universe could possibly be complex enough to compute its own actions, plus those of the rest of the universe. See path independence, irreversible process, and Entropy (arrow of time) just to start.

See also the works of Viscount Ilya Romanovich Prigogine. μηδείς (talk) 02:37, 20 August 2012 (UTC)

I'm thinking theory can't prohibit everything, because (for example) it is possible that we scan the sky with a telescope and find an alien TV station broadcasting a video of their telescopic observations of the Earth 100 million years ago. Of course, that's not "the position of every atom", but it's a lot of detail. I doubt that there's any tiny particle, neutrino or otherwise, that can actually give this information if somehow you can observe a reflection or retransmission, but it doesn't seem conceptually impossible. See time viewer. Wnt (talk) 04:22, 20 August 2012 (UTC)

Well, perhaps a better statement would be, current understanding is that no, it's not possible. 203.27.72.5 (talk) 04:33, 20 August 2012 (UTC)

Well of course we could get aline TV, but even their TV wouldn't broadcast the action of each element on their homeworld. It is simply not possible to communicate X information without using X^N information, with N being some number above 1. μηδείς (talk) 04:36, 20 August 2012 (UTC)

I remember a homework question in statistical mechanics that illustrated just how hard this is to do, even when considering purely classical systems. Chaotic systems, of which there are many classical examples, have the property that any uncertainty will grow exponentially with time. Suppose you wanted to know the evolution of every molecule of the atmosphere in a 1 m cube. This requires knowing not only the starting position and velocity of every particle but also all the external forces present to exquisite precision. There are 10²⁴ particles in that cubic meter, each moving at high speed and the future of each particle determined by the billiard-like collisions with other particles. Each collision magnifies the uncertainty as small differences in initial position lead to large changes in the new direction of travel after collision. One can calculate that even if you knew the initial positions and velocities exactly, and if you knew all the forces present (e.g. the precise details of gravity, electromagnetism, and everything else) to a precision of 10^-100 N throughout the box, then that is only good enough to predict the path of the air molecules for a few minutes. After that, even this tiny error in specifying the forces present has been magnified to the point that you can no longer predict which molecules will collide and the whole thing becomes apparently random again. Because forces propagate over long distances, achieving even this few minutes of predictability would still require knowing every atom's position everywhere around the box for a distance of light years. And of course, this is considering only the purely classical parts of the problem, quantum mechanics will turn this practically impossible task into one that is truly impossible. Dragons flight (talk) 17:16, 21 August 2012 (UTC)

The physics and etc. of Total Recall (the 2012 remake)

I liked how the buildings looked in 2084, and was quite intrigued by "The Fall" super-elevator. I would hope their retirement homes by that time (as I'd likely live in one) would make a Chuck E. Cheese's look as boring as today's retirement homes by comparison.

Questions about The Fall:

F1) How could the difficulties of physics, the depth of the dig, et al., be overcome in order to build "The Fall" super-elevator that runs through the core of the planet?

F2) What "side-effects" would digging through the Earth's core cause?

F3) How much could "The Fall" cost, ballpark, to construct (in constant 2012 Euros?)

F4) How would the super-elevator be insulated from the core's excess heat & pressure?

F5) If any mechanical difficulty were to cause The Fall to stop somewhere in the shaft, many miles from either surface, what would be a suitable escape plan to bring the passengers back to the surface safely? (No point in ladders when you have 2,000+ miles to climb to a surface, unless they're also "tracks" for hyper-fast escape lifts.)

F6) To reach Australia from Britain in just 17 minutes, how could the acceleration and deceleration of The Fall be made gentle enough not to cause any significant ill effects for the passengers & crew?

F7) What would the terminal velocity be for an elevator big enough to hold 50,000 passengers and be as tall as a skyscraper?

F7.1) What would the propulsion methods have to be in order to race the elevator to the other side of the globe in just 17 minutes?

F8) Could the dig and installation be finished in just 72 years?

F9) What else could we plausibly invent in just 72 years to get from one end of the world to the other in 17 minutes?

F10) There was a scene where the characters opened an escape door and stepped outside during its ascent. Wouldn't there be some type of physical harm caused by the speed of the air flowing past you as fast as that elevator was going up?

Questions about the No Zones:

Z1) I was bothered that a global, chemical World War III could make much of the planet permanently uninhabitable. What kinds of chemicals would pollute the air in a non-dissipating fashion despite all sorts of wind, weather patterns, and the like? (They never dropped the "nuclear" term so I'd assume that no nuclear warfare took place.)

Z2) How effective would clean-up efforts be to clean the war's chemical pollution?

Z2.1) Why couldn't they keep cleaning up in order to make more living space available again?

Z2.2) If they had no problem building police "synthetics", why didn't I manage to see janitorial droids clean up the chemically-polluted wasteland?

Z2.3) How feasible could it be to get janitorial synthetics to clean up after our wars?

Z3) What new technologies could we invent to clean up after (that kind of) chemical warfare?

Z4) Above what height would the air have been safe above the "No-Zones?"

Z5) Why didn't I hear anything about undersea colonies? There is, after all, epic potential living space on and under the oceans.

Z5.1) If they have the engineering capability to construct "The Fall," how wouldn't they have the capability to build underwater, domed colonies? Amazingly enough, we already have something like this, albeit on a very small scale.

Miscellaneous "Total Recall" questions:

M1) Wouldn't the Holodeck be less invasive (no chemicals and tubes in arms, etc.) and overall, safer than the "Recall" chair?

M2) There was a scene where a tattoo was being worked on, that emitted varying types of light. What is the science and working behind luminescent tattoos?

M3) Would consumers really WANT a phone embedded in one's hand? Why not a glove-phone instead? Or a phone embedded on one's shirt/coat-sleeve? What other, future types of phones could we have for anyone who believes particular electronic implants could signify the Mark of the Beast?

M4) When living space is so scarce, why wouldn't that also spur us to build off-world colonies? We would have 72 years to make it feasible.

M5) How did The Fall become a "symbol of oppression?" And if it was, why wouldn't The Colony have prevented its construction in the first place?

M6) I noticed a Fiat Nuova 500 or two on the surface after the car descent scene. Given that it looks rather identical to the Nuova 500s made today, was there an antique car convention in town that day?

M7) Given that environmental movements (and their correlating tech advances) will make dead trees obsolete in 72 years, why would there still be a paper-based physical book-passport, as found in a bank deposit box?

B1) And as a bonus end-question, what other remakes are already in-theaters or are upcoming, that take place in a future? I was so fascinated by much of what I saw on this film. Thanks. --70.179.167.180 (talk) 04:51, 20 August 2012 (UTC)

I renumbered your Q's to give each a unique number. StuRat (talk) 06:44, 20 August 2012 (UTC)

F1) This part doesn't seem possible, at least in the time frame given. StuRat (talk) 07:46, 20 August 2012 (UTC)

F9) Telepresence is probably the best way to get to the other side of the world instantly. You could hook yourself up to virtual reality equipment, and a robot on the other side of the world would send all the sounds, sights, smells, tastes, and tactile sensations to the VR equipment, where you would experience them, and also control the robot. Teleportation may also one day be possible, but perhaps not in that time frame. StuRat (talk) 06:46, 20 August 2012 (UTC)

In the case of telepresence of 2 or more people, green screen technology could be used to make each person see the other when looking at their robot. StuRat (talk) 18:54, 20 August 2012 (UTC)

Some parapsychologists believe that Teleportation is possible now, but they have been unable to demonstrate it to science. There is no logical reason to believe that this magic will become possible in future. Quantum teleportation specifically states that it does not involve reconstruction of an object (or person) at the other end, much to the disappointment of Star Trek fans. The Sci-Fi concept doesn't seem to have any basis in reality by current scientific and informatics understanding. We should have an article somewhere that explains why it is impossible. Dbfirs 12:12, 20 August 2012 (UTC)

What is theoretically impossible about it ? It just involves scanning a person down to the molecular level, sending that information to the target location, synthesizing those molecules there, assembling them in the correct order, and "rebooting" the person (restarting their heart, etc.). Aside from the moral implications (no provision was made to transport the soul, so is destroying the original murder, with the copy being a clone ?), it all seems plausible to me. StuRat (talk) 19:00, 20 August 2012 (UTC)

Some time ago, I read a good article explaining from an informatics viewpoint why it will never be possible. Unfortunately, I can't remember where I read it. The argument was on the lines that the amount of information required for reconstruction of a human is just too big for any machine that will fit in the universe, but I probably haven't expressed it very well. Can anyone find a good article? Dbfirs 19:41, 20 August 2012 (UTC)

I suspect that they aren't allowing for proper data compression. For example, you don't need to send the position of every atom in every hemoglobin molecule. Just send the info that a hemoglobin molecule is located at positions X,Y,Z, and also send the detailed design of a typical hemoglobin molecule for that person (but only once). This could actually repair genetic damage, in that those hemoglobin molecules that are not typical would be replaced by those which are (so long as they remain close enough for the scanning device to figure out what they are supposed to be). StuRat (talk) 19:48, 20 August 2012 (UTC)

Also, it isn't necessary to store all the info at once. You can scan one cell, send it's info on to the remote site, clear the buffer, scan the next cell, send it's info on, etc. At the remote site, they can get the info for one cell, create it, clear the buffer, get the info for the next cell, etc. StuRat (talk) 23:30, 20 August 2012 (UTC)

So if you could make a copy of the person in this way, what happens to the original? 203.27.72.5 (talk) 20:30, 20 August 2012 (UTC)

You either destroy it or you have an identical clone. This is the moral problem, either way. There was a (new) Outer Limits episode dealing with this moral issue: [1]. StuRat (talk) 21:27, 20 August 2012 (UTC)

I think the cell-by-cell method would take far too long for the duplicate to stay alive, but I can't find the article. I don't think I imagined it! Anyway, we agree that the concept has interesting moral implications, and, if possible at all, is not achievable by any method known to science at present. It will be interesting to see how long it is before 3D printers try to create a simple cell. Dbfirs 19:11, 21 August 2012 (UTC)

Z1) Plenty of chemical pollutants last a long time, like CFCs, PCBs, and PBBs, and DDT. StuRat (talk)

Z3) Nanites could search the world for pollutants, and convert them into something harmless, while also reproducing themselves. Genetically engineered bacteria might be another approach to do the same thing. StuRat (talk) 06:38, 20 August 2012 (UTC)

Z5) I agree that undersea colonies would be a good idea. Unlike in space, both oxygen and water can be derived from sea water, temperature maintenance is easier, there's protection from the radiation and meteors of space, and potentially food can be derived from sea water as well (depending on how badly it was polluted). It also takes less energy and expense to move to and from the Earth's surface to there. Also, if they can build domes under the water, why not on the land, as well ? Presumably they could clean that small area of contaminants and keep it clean. StuRat (talk) 08:45, 20 August 2012 (UTC)

M1) The Holodeck, as in STNG, requires teleportation technology to reposition you in the center of the room if you move near a wall. So, probably too ambitious for this time frame. Virtual reality could work, though. However, I think part of the selling point of the implanted memories is that you can feel as if you've spent a great deal of time on vacation, while actually not "wasting" all that time that could be spent in more productive activities. StuRat (talk) 08:00, 20 August 2012 (UTC)

M2) There are bioluminescent substances, and they could be engineered to generate light from blood sugar. However, they wouldn't be very bright. You could probably only see them in the dark. StuRat (talk) 06:38, 20 August 2012 (UTC)

M3) I'm with you here, although you could never forget your phone if it was part of you. Really, I think they are small enough now. What we need to work on is the functionality. Better cameras, better voice recognition, longer battery life, better reception, lower cost, etc. Incidentally, an electronic device can be too small. Watch calculators, for example, never really caught on. StuRat (talk) 07:33, 20 August 2012 (UTC)

M6) Future cars are always problematic for movies. It's rather expensive to design an entirely new car for a movie, even with CGI. So, you often get a slightly modified current model. In this particular case, you might be looking at a case of product placement. StuRat (talk) 07:42, 20 August 2012 (UTC)

M7) Electronics are nice, but you still want more permanent records of certain things. That wouldn't need to be paper, necessarily. I'm looking forward to a more permanent digital data format, some day. Perhaps a crystal with atoms replaced in certain lattice locations to represent bits of data. StuRat (talk) 07:40, 20 August 2012 (UTC)

B1) (I didn't limit my answers to remakes.) You might want to see the movie Surrogates, if you haven't already. I assume you've seen The Matrix and it's sequels. I'd also recommend Bicentennial Man, A.I. Artificial Intelligence, and I, Robot. StuRat (talk) 06:33, 20 August 2012 (UTC)

F6) Constant 1G acceleration is pretty bearable. It's what you've experienced in free fall any time you've ever fallen (or jumped). It wouldn't get you there in that time though. You'd need about 5G of acceleration and deceleration to make it there that fast. 203.27.72.5 (talk) 07:27, 20 August 2012 (UTC)

Yes, and you could even go to 2g, which would feel like 1g, since 1g feels like no gravity at all, while in free fall. This would, however, require more energy. StuRat (talk) 07:44, 20 August 2012 (UTC)

F7) If the elevator shaft was a vacuum there would be no terminal velocity. The elevator would accelerate until it reached the midpoint and gravity would slow it down from there. To complete the trip in 17 minutes, gravity is not sufficient however, and the midpoint velocity would be 89,964km/hr 203.27.72.5 (talk) 07:44, 20 August 2012 (UTC)

F7.1) I don't know what the propulsion methods would be but a rail gun type system would see appropriate. As a side note, gravity alone would not get the elevator through the earth in 17 minutes. Even if you assume that you get 9.8m/s² for the whole first half of the trip, after 8.5 minutes (510 seconds) you've only gone 1,274km of the 6371km of the Earth's radius. To get there in 17 minutes you'd have to accelerate at 49m/s² (~5G), which causes disorientation, dizziness and fainting in humans. 203.27.72.5 (talk) 07:44, 20 August 2012 (UTC)

F10) Ok, so if the elevator shaft was not a vacuum then yes there would be huge problems for anyone stepping out of the craft. If we assume that it was atmospheric pressure (so that he could breath in it) then you can compare it to this rail gun. The projectile there is moving at 9000km/hr. If the elevator has a uniform acceleration then it is travelling that fast 51 seconds after it leaves one side of the Earth. Note the unsurvivable ball of ionized gases in the linked picture. 203.27.72.5 (talk) 08:03, 20 August 2012 (UTC)

However, the air in the shaft might also move with the capsule, particularly if it was the driving force in a pneumatic system. StuRat (talk) 08:11, 20 August 2012 (UTC)

I can only imagine that what you mean here is that the capsule is like a piston moving through a cylinder making a seal with the sides as it slides through. The two obvious problems with that are, friction on the side walls (remembering that the peak velocity is 90,000km/hr) and plasma shock wave moving up through the column to the destination. Actually, the plasma shock wave probably applies to any version that doesn't use a vacuum. 203.27.72.5 (talk) 23:12, 23 August 2012 (UTC)

I haven't seen the movie but agree any plausible "Fall" would be in vacuum. Otherwise it's not that much better than flying there in a regular hypersonic airplane. But there's a vastly larger problem, which is that the Earth's core rotates relative to the surface. Though as long as you have magic hole-boring and -holding technology, maybe the impenetrable walls of your shaft stopped it. ... ...

Implanted memories are indeed the true mark of the beast, and have vast social implications. You have a choice of two workers. Now Duh is a bright fellow, spent twelve years in grade school, four years undergrad, maybe five more getting a Ph.D., and now he's a novice expert in his field. Whereas Spiffy got the memory download of an expert when he was a little kid and has been working at it ever since. More importantly, Spiffy's artificial hippocampus downloaded the attitudes of the selected senior engineer, which include a once-rare sense of absolute loyalty and deference on personal issues that has since been tested in hundreds of thousands of workers conditioned with his thoughts and beliefs. Now if you're one of the six people who own the world, who are you going to hire, Duh or Spiffy? Wnt (talk) 13:54, 20 August 2012 (UTC)

Also important is that if you did have this massively strong tube running through the centre of the Earth that could widthstand the movement of molten iron alloys in the core, it would disrupt the flow of those alloys to some degree, possibly enough to alter the power or orientation of the geodynamo that generates the Earth's magnetic field. 203.27.72.5 (talk) 21:10, 20 August 2012 (UTC)

If the tube was not a vacuum, the air pressure would be higher than 1atm at great depths within it because the height of the column of air would be huge. If the pressures are higher, then there's more air there, so given the massive scale of the structure, building it might cause a significant fraction of the atmosphere to flow into it, lessening the amount we have up here. That would mean we have less protection from uncharged solar and cosmic radiation. Also, what happened to all of the rock that was pulled out of this hole? 203.27.72.5 (talk) 21:23, 20 August 2012 (UTC)

Thanks, you all! I loved your valuable answers! This might get an architect for the real "The Fall" to realize what obstacles s/he'll have to overcome before getting started.

Now, I know some questions remained unanswered. Would anyone care to tackle those this time? --70.179.167.180 (talk) 03:19, 23 August 2012 (UTC)

Well, some of them are just problematic (most of the "why didn't the filmmakers..." questions are answered "because they didn't") but to try a few: to go around the world so quickly see hypersonic aircraft - you want to go 12,000 miles in 17 minutes = 42352 mph, which is in excess of "reentry speeds". So you'd need some kind of vacuum-filled enclosure to do it in any case - going the long way around takes 3.14 times longer, but it's a lot easier to make. But the acceleration would be accordingly that much more than the already crushing acceleration needed to make a "Fall" really get there in time, and that's only feasible if you have some kind of very good protection against acceleration (like sending only certain inanimate objects, or people with nanotech-reinforced internal structures...).

It seems easier to envision making areas biologically uninhabitable (with the proposed sustained use of Terminator technology mosquitoes to control population numbers,^[2] ridiculously easy, any decent biology grad student ought to be able to manage it with enough determined effort). Nonetheless, the old Strangelove Cobalt-thorium-G bomb still seems practical enough, as long as people don't stop worrying about cancer.

Implanted phones are obviously a terrible idea, but presumably that was the point? (I didn't see it). Right now it doesn't seem to be at all hard to talk idiots into building the walls of their own cages.

Even not seeing it, the car was obviously product placement - I've seen some films just totally give up all credible effort to explain why they have ads in the middle. Wnt (talk) 21:57, 24 August 2012 (UTC)

Relationship between electricity and intelligence

I have noticed that anything which could be described as an intelligent agent depends on electricity, including computers and the human brain. Is there any reason for this? Could you create a purely mechanical computer with an artificial intelligence? Widener (talk) 07:10, 20 August 2012 (UTC)

I guess one reason is because electrons are nice and small so you can store lots more information with them than if you were to use larger particles. Widener (talk) 07:11, 20 August 2012 (UTC)

Yes, and also quick. Mechanical adding machines were quite large and slow, by comparison. StuRat (talk) 07:19, 20 August 2012 (UTC)

Indeed. A billiard-ball computer wouldn't be restricted to arithmetic-type operations. DMacks (talk) 07:24, 20 August 2012 (UTC)

Here's a proper billard ball computer Giant Digicomp II. Dmcq (talk) 14:04, 20 August 2012 (UTC)

I have one of the old Digicomp I machines. Wonder how many more I can find and multiplex and if it'll boot linux? DMacks (talk) 15:47, 20 August 2012 (UTC)

Although nowhere near being technologically achievable currently, it's at least theoretically possible to construct a purely mechanical computer which far outperforms current electronic computers in terms of gates per given volume, or in terms of instructions per second per watt. See the "Nanomechanical Computational Systems" chapter of the book "Nanosystems: Molecular Machinery, Manufacturing, and Computation" by K. Eric Drexler. Drexler's PhD thesis, which served as a rough draft of that book, can be read for free online.[3] Red Act (talk) 15:35, 20 August 2012 (UTC)

As far as whether it will ever be possible to actually construct such devices, see Drexler–Smalley debate on molecular nanotechnology. Red Act (talk) 19:34, 20 August 2012 (UTC)

There are countless "things" you could notice that share a dependance on electricity, is there a reason for this? Probably because electricity is one of the fundamental forces. Also, I don't think anyone with a grasp of the topics involved would consider desribing computers as "intelligent agents".. But yes, there is nothing particularly special about "electricity" which gives it any unique intrensic properties. Essentially, all the electricity does is perform Boolean algebra, just really really fast. You may also be interested in Turing machine and Turing complete. Vespine (talk) 22:58, 20 August 2012 (UTC)

In megatons, what is the total estimated yield of the world's nuclear stockpile?

The title says it all. I'm certain that data exist on this somewhere (I'm fairly certain I've even heard numbers quoted, many years ago), but I've been unable to locate them. Evanh2008 ^{(talk|contribs)} 08:19, 20 August 2012 (UTC)

"The total global nuclear arsenal is about 30,000 nuclear warheads with a destructive capacity of 5,000 megatons or 5 gigatons (5,000 million tons) of TNT" from TNT_equivalent#Examples. No source is cited. 203.27.72.5 (talk) 08:31, 20 August 2012 (UTC)

There are reasons to doubt that estimate — it is pretty out of date. The best estimates put the total stockpile size at 19,000 total, 4,800 operational. Awhile back I did a back-of-the-envelope guess based on published estimates from the Bulletin of the Atomic Scientists "Nuclear Notebook" series (which annually estimates the size and composition of various world nuclear stockpiles) and came up with a range of between 1.7 and 2.2 Gt, but if you made certain other assumptions you could get it up to 3.5 Gt plausibly. (I may have the numbers I used somewhere in an Excel spreadsheet, but not at hand.) The short answer is "nobody really knows, because the exact compositions of the world nuclear arsenals have not been disclosed, but it's probably a few gigatons." It's a lot less than it was during the Cold War, obviously, both because the number of weapons has been drastically cut back and the big nuclear states these days favor "just" large nukes (e.g. in the hundreds of kilotons range) rather than the ridiculously scary nukes of yore (megaton range). During the Cold War the "standard" estimates were around 5-10 gigatons. Note that just for comparison, all of the explosives expended during World War II, including the first atomic bombs, add up to just a few megatons. --Mr.98 (talk) 13:00, 20 August 2012 (UTC)

Thanks for the replies and the links! Quite helpful. Evanh2008 ^{(talk|contribs)} 01:18, 22 August 2012 (UTC)

absorption of vitamins

Hello, I'd like to know if vitamins delivered through the digestion of vegetal cells were better absorbed than vitamins delivered “as is” through powder nutritional complements and fruit juice? Without protection, these vitamins will undergo the acidic digestion of the stomach and may be degraded. I know that some medical complements of vitamins (or of calcium) are administrated in non-digestible shells that open only when the intestine is reached, so as to protect its nutrients from the digestion of the stomach (the shells are then naturally excreted). 79.94.61.31 (talk) 09:20, 20 August 2012 (UTC)

I thought the shells were digested somehow? I've been taking such vitamins for decades and have never seen shells in my excreta! --TammyMoet (talk) 17:55, 20 August 2012 (UTC)

Unfortunately, the vitamin and supplement industry is very lucrative and very poorly regulated, a terrible combination. It's extremely common, almost universal that supplement manufacturers advertise using wild claims based on the flimsiest science, constantly flirting with the line between what is letigious and what just passes whatever little standard they are held up to. There is actually very little evidence that daily vitamin supplementation has any benefit what ever, unless you are actually malnourished or have a clinical deficiency. Basically, if you live in a 1st world country and get 3 meals a day, even if your diet isn't that great, you most likely won't actually get any benefit from dietary supplements. As to the question, yes, I'd be willing to bet that eating vegetables is almost certainly better for you in the long run then popping some pills. Vespine (talk) 23:12, 20 August 2012 (UTC)

All I know is that I feel better when I take them than when I don't. Nowt wrong with a good placebo... --TammyMoet (talk) 08:14, 21 August 2012 (UTC)

Of course people "feel better" when they take them, otherwise I very much doubt it would be a mutli billion dollar industry. I "feel better" after I have a cigarette, but it's kind of entirely beside the point. The question is do they actually have any benefit like they claim. Vespine (talk) 04:13, 22 August 2012 (UTC)

Well, there could be. It's possible to overdose on some vitamins and minerals, and they may contain sodium and sugar. Also, if they come from China, God knows what's in them. And, there are often multiple forms of a particular vitamin, some of which are easier to absorb than others. However, they often pick whichever form is cheapest. StuRat (talk) 08:25, 21 August 2012 (UTC)

Checking a few vitamines, they all seem to be reasonably stable in acidic conditions. Some of them are acids themselves, and a few (like thiamine) come in the form of HCl salts (which are more stable than the free base form). Extended-release forms (like for high dose niacin) would by their nature protect (part of) their contents from exposure to stomach acid. Depending on essential nutrients that need protection from gastric acid might be an evolutionary dead end. Ssscienccce (talk) 23:47, 20 August 2012 (UTC)

Biology is neither perfectly understood nor an exact science, and there are always possibilities for ways in which synthetic supplement vitamins will not be as good as the natural nutrients. For example, the combination of vitamin D with calcium was not always known. There are issues about the precise form of vitamin A, beta carotene, etc. which is best. Other vitamins like cyanocobalamin are just one of several forms. And of course, the dosages are always under dispute, some saying that too much is dangerous, other that the existing dose is woefully insufficient. Even for one person, facing a range of medical risks which different people might prioritorize differently, there may be no "best" vitamin regime, because, say, some people care more about performance, others about the risk of cancer. For a genetically diverse population with vastly different eating habits...? My feeling, nonetheless, is that people may have some valid internal feedback after trying vitamins, and that if something makes them feel good, we may not know whether it is truly good in the medical sense, but at least it does that. And, however difficult it is to come up with a perfect solution, one can identify certain deficiencies that are relatively common, e.g. riboflavin. Certainly it is more ethical to sell people supplement pills which might alleviate a real riboflavin deficiency than to continually sell them products for "chapped lips" which merely grease over the symptoms. (Though as the article points out, that can also be caused by excessive intake of vitamin A...) Wnt (talk) 12:52, 22 August 2012 (UTC)

Plutonium tetroxide

Is PuO₄ known? If so, how is it synthesized (and what's the ref)? If not, how could it possibly be synthesized, or, if it's most likely not possible, why? Double sharp (talk) 10:14, 20 August 2012 (UTC)

See here. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 12:21, 20 August 2012 (UTC)

I'm not a nuclear chemist, but the article seems to say: people have wondered if plutonium tetroxide could be synthesized, especially since ²³⁹NpO₆ decays into ²³⁹PuO₆; then follows some theoretical discussion, buffered by some experimental work, implying that it's possible that plutonium tetroxide could be made to work. "All these facts allow us to assume that the organic phase of nonpolar solvents contains neutral molecules of the previously undescribed compound of octavalent plutonium in the form of the corresponding tetroxide." My lay interpretation of the article is, "we think it can be done, we've no idea how to do it, even as experienced nuclear chemists, though maybe we've already found it but not proved it." --Mr.98 (talk) 13:09, 20 August 2012 (UTC)

Neuron Anatomy

I have been talking about Savant Syndrome with Dr Darold Treffert. The symptoms seem to be narrowed memory recall. Also he thinks Einstein is not autistic, he is a neuron typical genius. A person does not have to be autistic to be a savant and it could happen to anyone, including later acquired abilities. Which raised an interesting question, what is the anatomy of a savant brain? Is there any common structure that lead to the abilities? Would there be similarity to Kim Peek's brain? Did anyone do any research in this area or have any data to share? Thanks! -- RexRowan Talk 09:22, 20 August 2012 (UTC) Copied from Wikipedia_talk:WikiProject_Neuroscience#Neuron_Anatomy

canon 650d, Magic Lantern

I need to know which is the actual video recording bitrate of the 650d Someone know if there is magic lantern support for it in this moment? Thank you Iskánder Vigoa Pérez 15:52, 20 August 2012 (UTC) — Preceding unsigned comment added by Iskander HFC (talk • contribs)

This has been asked and answered on the Computing desk. Rojomoke (talk) 16:22, 20 August 2012 (UTC)

Please add Vascepa (isosapent ethyl) to Wikipedia Encyclopedia

Hi, Vascepa (isosapent ethyl) was recently approved by the FDA as a triglyceride lowering medication. The company that manufactures it is Amarin. I believe it was approved late last month, July. Can you add this drug?

http://www.vascepa.com/

Thanks! — Preceding unsigned comment added by 68.11.125.232 (talk) 16:24, 20 August 2012 (UTC)

We've had an "Ethyl eicosapentaenoic acid" article for many years now, and Icosapent is a redirect that points to it. DMacks (talk) 16:29, 20 August 2012 (UTC)

I just now added a redirect for Vascepa. Red Act (talk) 17:05, 20 August 2012 (UTC)

maxwells inductance capacitance bridge

why we connect inductor in se & capacitor in parallel in maxwells inductance capacitance bridge — Preceding unsigned comment added by Sanathwiki (talk • contribs) 16:58, 20 August 2012 (UTC)

This doesn't answer the question, but for reference the article on the topic is Maxwell bridge. Red Act (talk) 19:37, 20 August 2012 (UTC)

It looks like R3 & L3 are actually the unknown (the component or components we want to measure) and the R3 and L3 in the schematic are representing the two properties of a physical inductor. A real world inductor has some finite internal resistance (the wire it is wound from has resistance) unlike the idealized model which could have inductance without resistance. That explains why R3 and L3 are in series. If we put the capacitor and resister in series would it work? Maybe (depending on frequency), but the formulas would be different and possibly not as nice to work with. (Sorry, In don't remmeber ever seeing the Maxwell bridge in school so I'm kind of guessing.) RJFJR (talk) 21:12, 20 August 2012 (UTC)

If my understanding is correct, the Maxwell bridge has the cool property that the R2 and C2 settings that balance the bridge at one nonzero frequency will also balance the bridge at any other frequency, including zero. So it's possible to get the correct setting for R2 by using DC input and just adjusting R2, since the C2 setting won't affect things at DC. The R2 setting can then be left alone while just C2 is adjusted at some nonzero frequency. That same procedure wouldn't work if R2 and C2 were in series, and it'd be necessary to go back and forth between adjusting R2 and adjusting C2 to get the thing to balance, which wouldn't be nearly as convenient. The equations for R3 and L3 would also be more complicated in the altered circuit, since they would depend on the frequency. Red Act (talk) 22:06, 20 August 2012 (UTC)

There are two important reasons for putting the resistor in parallel with the standard capacitor and not in series, and one minor reason. The first important reason is the one cited by Red Act - it makes the bridge balance independent of frequency - this means that a precision oscillator is not required. The second, just as important, reason, is that it makes for a much more convenient/practical resistance for R2. Consider a typical bridge with the standard capacitance of 1 μF (acurate values much above this are VERY expensive) and an energisation frequency of 1600 Hz - the reactance of the standard capacitance will be 100 ohms. Let's say we are measuring an inductance with a Q of 100 - a pretty ordianry value. To balance it, a series R2 would need to be 1.0 ohms. The slightest contact resistance (which after the bridge has seen some year's use might vary for 0.02 to 0.5 ohm from one setting to another) is a significant fraction of the total, and will make balancing a touchy and annoying task. But a parallel R2 will need a value of 10,000 ohms. This will swamp out any likely contact resistance over the service life of R2. The third, minor reason for a parallel R2 is that it also makes balance insensitive to any oscillator harmonics, so you can use a real cheap oscillator and an untuned detector. With a series R2, if you set it for balance at the fundamental, the bridge will be unbalanced for any oscillator harmonics, and the higher the harmonic the worse the unbalance. Keit58.164.239.117 (talk) 01:52, 21 August 2012 (UTC)

What's the percent of NASA projects that get canceled before completion?

Is it over 50%? I don't even raise an eyebrow when I hear about some project that is currently alive, because my perception is that whatever it is, the odds are in favor of the project being canceled before they actually do the thing the project sets out to do. That's my perception, at least. Does the data reflect this? 20.137.18.53 (talk) 17:47, 20 August 2012 (UTC)

Almost by definition, zero programs are cancelled before completion. Whether certain specific goals of a specific project are attained is a different question. The way NASA and other government projects work is to outline very specific objectives, schedules, and funding programs. Once approved, the money is effectively "already spent." It's very difficult to "un-spend" that money. Projects or programs that are very successful are followed on by new projects with new funding. Less successful projects are rarely rewarded with follow-ons and new programs. High-level strategic objectives, like "putting a Mars sample-return program together," are not actually "projects" - they're strategic goals that evolve with time, and are supported by individual research and operations programs. So, the goal of a sample-return mission is never "cancelled;" but it can be re-evaluated from year to year, and it can be de-emphasized by changing the management of individual operational programs.

You can see the full breakdown of all projects, and their budgets, here: NASA main budget webpage. Here's the "Performance Report", which quantitatively breaks down past and planned performance for programs and projects, including a lot of discussion about how to measure "success." Nimur (talk) 18:57, 20 August 2012 (UTC)

If your definition of "cancel" is to not spend any money on a project, I don't think that's how most define it. In the case of NASA, stopping the project prior to (rocket) launch is what I would call cancellation. In the case of a project not involving a launch, like say funding a Neil deGrasse Tyson TV show, cancellation would mean that it is stopped before ready for broadcast, etc. StuRat (talk) 19:09, 20 August 2012 (UTC)

Maybe I should have used the word 'mission' instead of project. Basically, the thing that gets pushed to the public as "Look what we're going to do!" 20.137.18.53 (talk) 19:08, 20 August 2012 (UTC)

Take the example of Pluto Kuiper Express. That mission never launched. But, New Horizons did... so one can legitimately say that the mission to explore Pluto with a robotic probe was not cancelled. At the same time, certain line-items specific to the previous mission plan were cancelled. Two statements that seem, at least superficially, to contradict, are both true. So, unless you are willing to dig into the details, it's meaningless to talk about whether the "mission" was cancelled. NASA, like any large government organization, changes its plans, and is constrained by budget. Nimur (talk) 21:15, 20 August 2012 (UTC)

OK, as for a slightly more specific subset of NASA "aspirations" (let that be a semantic umbrella term), how many times since the last time a human literally took off on a trip to the moon have they said "we're sending humans back by year X" only to have that specific plan be "modified" to "no, we're going to now send humans back by year Y," and so on, with perpetual constraint-induced inability to complete "aspirations" as currently specifically planned.? 67.163.109.173 (talk) 21:35, 20 August 2012 (UTC)

I'm not trying to be needlingly pedantic, but you failed to explicitly state who "they" are. For example: in 2004, the President committed to a manned moon mission by 2020, but in the same report, you'll find that NASA administrator O'Keefe did not explicitly acknowledge that commitment. So, ... a question of political semantics: did NASA, in 2004, commit to a manned moon mission? If you believe yes, you might truthfully say that NASA has reneged (to be safe, you might wait until 2020 before). On the other hand it might be fair to say that NASA never committed to the former President's policy, so they can't be blamed for "cancelling" the objective. Nimur (talk) 22:01, 20 August 2012 (UTC)

OK, if non-binding commitments released to the press by the President have no bearing to the agencies that are not at all committed by said "commitments," and are not worth the paper they're printed on, that makes it more difficult to actually believe anything a president or a politician or anyone not actually in a position of authority at the agency itself has to say about things supposedly to be accomplished by said agency. 67.163.109.173 (talk) 22:11, 20 August 2012 (UTC)

My example was only to illustrate how subjective the answer to this question can be. In my opinion, a commitment is non-binding until there's money behind it. Even if the statement is made by the President. Nimur (talk) 22:14, 20 August 2012 (UTC)

I guess all I'm saying then is if I were at NASA, I'd get pissed at politicians writing checks my butt can't cash for votes, knowing that a significant portion of vote-bearing citizens may not make the distinction that there's as much binding between the politician's words and NASA's acts as their (the voter's) own. Then when it never materializes long after the politician's gotten the short-term approval for saying the lofty things, people get pissed at NASA for not pulling a miracle out of their collective behinds by doing it without any money. 67.163.109.173 (talk) 23:12, 20 August 2012 (UTC)

As a general rule, any commitment that a politician makes to do something which is to actually happen after their term in office has expired is just grandstanding. 203.27.72.5 (talk) 23:23, 20 August 2012 (UTC)

The problem with that is that many NASA projects do require more than 8 years from conception to completion. So, if a politician starts a project and fully funds it during his term, I'd give him credit for that, even if the next administration cancels it. If, on the other hand, they announce grand plans, but have no intention of funding them during their term, then I agree with you. StuRat (talk) 02:50, 21 August 2012 (UTC)

What about if the President comes up with a budget to fund it, along with a very large deficit and Congress rejects that budget and makes their own cutting down on stuff which includes this project, to reduce the deficit? Nil Einne (talk) 03:51, 21 August 2012 (UTC)

Talk is cheap. The first Bush was going on about moon bases and Mars trips in 1989.^[4] I imagine that when his great-grandson is president, he'll still be promising Mars to the peasants to help whip a tax increase out of them, and invest it all in a penthouse in Rio de Janeiro. Wnt (talk) 12:12, 21 August 2012 (UTC)

In case it isn't obvious to everybody reading this: the President of the United States can't actually give NASA any money to achieve a goal such as putting people on the Moon. The budget is entirely up to Congress. So, the President setting such a goal has no effect whatsoever, except insofar as it aids in convincing Congress to fund such a program.--Srleffler (talk) 16:28, 21 August 2012 (UTC)

Well, he could just veto budget bills that don't include his proposal until congress comes around, but I think you'd need a president from the Space Cadet Party to have that much resolve on this issue. And even then congress could always just override his veto. 203.27.72.5 (talk) 23:44, 21 August 2012 (UTC)

I've heard of Congress threatening to withhold supply (Wdoesn'tHAAOE?!) plenty of times. This is the time I've seen it suggested that the President could refuse supply! That would be the ultimate death or glory play! --Tango (talk) 22:24, 22 August 2012 (UTC)

Also, my understanding is that as Commander in Chief, he could order DARPA to do it with any funds already appropraited by congress. 203.27.72.5 (talk) 23:48, 21 August 2012 (UTC)

Unfortunately, you would need funds for longer than one budget, and Congress could refuse the next one if its last one was too badly misspent. --Tango (talk) 22:24, 22 August 2012 (UTC)

It cannot be used to compute a percentage but at Category:Cancelled space missions you can see what happened in some cases. PrimeHunter (talk) 13:15, 21 August 2012 (UTC)

Thanks for the good laugh at Edward Makuka Nkoloso :) 20.137.18.53 (talk) 16:21, 21 August 2012 (UTC)

Unknown snake in the Pantanal

I took a photo of this snake crossing the Transpantaneira in the Pantanal. I tried to, but was unable to identify the species. Can anybody help? --Leyo 19:49, 20 August 2012 (UTC)

Looks something like this blue mutation of the green tree snake, but with less yellow on the bottom at the front: [5]. Not sure if those are native to Brazil, though. StuRat (talk) 20:25, 20 August 2012 (UTC)

Green tree snakes are found in Australia and islands in this region. I forgot to mention that the snake was 2–3 meters long. --Leyo 20:36, 20 August 2012 (UTC)

Could it be an invasive species in Brazil ? Or perhaps a related species ? Here's a better pic of a green tree snake (Dendrelaphis punctulatus): [6]. StuRat (talk) 22:27, 20 August 2012 (UTC)

It is not impossible that it is an invasive species, but I guess the probability is not too high. --Leyo 09:40, 21 August 2012 (UTC) PS. Most probably the species is on this list of Brazilian reptiles or this list for the Pantanal. There is also a book on the biota northern section of the Pantanal

It has the rather prominent keel similar to that in sipos (genus Chironius), but I can't find any species with that coloration, except possibly the Amazonian whipsnake (Chironius exoletus). The crown ground snake (Liophis viridis) is closer in color but lacks the keel. Have you tried posting in herp forums? Someone might know enough about scale patterns and number to figure it out. ;) -- OBSIDIAN†SOUL 14:40, 21 August 2012 (UTC)

There are two Chironius species, Chironius laurenti and Chironius quadricarinatus on this list. There are also five Liophis species on the list, but not the one you mentioned. --Leyo 17:16, 21 August 2012 (UTC)

Congrats, you found it. :) It's Chironius laurenti. See bottom-most picture from the main page of Pouso Alegre.-- OBSIDIAN†SOUL 17:52, 21 August 2012 (UTC)

Thank you. Yes, it looks like. Let's hope the people of this lodge have a good knowledge on fauna. According to this page (in German), this snake is only 0.5–1 m long, which would not fit. There might be some information in this paper. --Leyo 23:06, 21 August 2012 (UTC)

Reptilebase also has a dark brown juvenile specimen in its picture. I don't have JSTOR accesss, but I found a paper saying what I suspected, snakes in the genus Chironius go through ontogenetic color change - they change color as they grow older. -- OBSIDIAN†SOUL 01:36, 22 August 2012 (UTC)

I got access to the JSTOR paper, but there was no information on the length of Chironius laurenti. Maybe there would be some in DIXON, J. R., J. A. WIEST, JR., AND J. M. CEI. 1993. Revision of the Neotropical Snake Genus Chironius Fitzinger (Serpentes, Colubridae). Monografie XIII. Museo Regionale di Scienze Naturali, Torino, Italy. --Leyo 14:29, 22 August 2012 (UTC)

Yeah, it's the article the species was originally described in after all and should contain the diagnosis of the type specimens. The summarized version of Dixon et al. on Reptilebase certainly fits your specimen: "females keeled and a mottled ventrolateral pattern on posterior of body and tail". There's a chance that Dixon et al. used a juvenile as the type, however, which might explain the 0.5 to 1 m length. It might also be sexual dimorphism which is exhibited by members of the genus, usually the female is significantly larger than the opposite. It might also just be an uncommonly large specimen, the average maximum SVL for adult Chironius carinatus for example is around 1.75 m, but apparently they can grow up to 2.8 m. C. laurenti is also a relatively very new species, having only been described in 1993, and probably still not studied that intensively as the more common and longer-known species. -- OBSIDIAN†SOUL 15:12, 22 August 2012 (UTC)

You are probably right. I'll get Dixon et al. 1993 (ISBN 8886041055) tomorrow and will check what information is in there. --Leyo 13:18, 23 August 2012 (UTC)

I created the stub Chironius laurenti based on Dixon et al. 1993. I hope I got the information right. It is not that easy for a non-native lay reader… --Leyo 13:20, 24 August 2012 (UTC)

Good work. I tweaked the article a bit. Glad this resulted in an article. :) -- OBSIDIAN†SOUL 14:33, 24 August 2012 (UTC)

Thanks for tweaking. :-) --Leyo 14:54, 24 August 2012 (UTC)

Cabbage and lettuce

How closely related are cabbage and lettuce? --168.7.239.105 (talk) 23:19, 20 August 2012 (UTC)

Not very. Cabbage is a cruciferous vegetable, while lettuce is not. The most obvious difference to the consumer is that cabbage gives you gas, while lettuce does not. Cabbage is more closely related to Brussels sprouts. StuRat (talk) 23:24, 20 August 2012 (UTC)

The relevant article is wild cabbage which was native in costal southern and western Europe: Brassica oleracea; cabbage, brussle sprouts, broccoli, cauliflower, kale, kholrabi and a few others are actulally just cultivars of the same plant, I've heard it described almost like dog breeds are clutivars of the same animal, not sure how loose that analogy is . Lettuce on the other hand was cultivated from weeds in Egypt. Vespine (talk) 00:22, 21 August 2012 (UTC)

In taxonomic terms cabbage, both are generally considered core eudicots but cabbage is generally considered to be in the Rosids clade while lettuce in the Asterids clade [7] [8]. In other words their relation is fairly distant. While StuRat is correct cabbage is more closely related to brussel sprouts, as Vespine says, those are all very closely related, so closely related that usually they are considered the same species. To use other random examples to perhaps better illustrate the distance, lettuce is more closely related to the blueberries, cranberries, kiwifruit, azalea, potatoes, sweet potatoes, eggplant, petunia and forget-me-not while cabbage is more closely related to strawberries, apples, roses, cannabis, Rafflesia, pumpkin, watermelon, cucumber, pecan and walnut. Of course, being eudicots, they are more closely related to each other then they are to say rice, maize, onions, lilies, orchids and bananas. Nil Einne (talk) 01:13, 21 August 2012 (UTC)