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August 18

Who is this beetle?

What is this lovely beetle? I found it on my front porch today, in Kernville, California. It's about an inch and a half long. --jpgordon^{::==( o )} 01:13, 18 August 2012 (UTC)

Looks like a potato beetle with inverted colors. Some variation, perhaps ? StuRat (talk) 01:58, 18 August 2012 (UTC)

It looks like a female ten-lined June beetle. Although its difficult to see how large its antennae are in the photos, it does not appear to have the large distinctive antennae of the males of this species. -Modocc (talk) 03:09, 18 August 2012 (UTC)

Yeah female. But it could be any of three easily confused and sympatric species of Polyphylla though - Polyphylla decemlineata, Polyphylla nigra, or Polyphylla crinita. There's a [highly technical] species key here, but different sources offer different contradictory diagnostics. -- OBSIDIAN†SOUL 06:59, 18 August 2012 (UTC)

Thanks! And indeed, I forgot to mention that this lovely beetle was "hissing" as described in the article. June beetle indeedle! --jpgordon^{::==( o )} 15:43, 18 August 2012 (UTC)

That is a mint humbug. 2.97.21.248 (talk) 02:32, 22 August 2012 (UTC)

+9 oxidation state

Can any element take a +9 oxidation state? I heard somewhere on-wiki (now forgotten) that IrO₄⁺ would afford the best chance for +9. I also read that meitnerium may be capable of it.--Jasper Deng (talk) 02:49, 18 August 2012 (UTC)

Apparently spectra of Ir(IX) have been observed. 203.27.72.5 (talk) 04:13, 18 August 2012 (UTC)

The wikipedia article that you read it in was most likely Iridium#Compounds where it says, "it was reported in 2009 that iridium(VIII) oxide (IrO4) was prepared under matrix isolation conditions (6 K in Ar) by UV irradiation of an iridium-peroxo complex.". 203.27.72.5 (talk) 04:16, 18 August 2012 (UTC) Sorry, that's not the cation you're talking about. 203.27.72.5 (talk) 04:19, 18 August 2012 (UTC)

(edit conflict)But that is in an excited state, and therefore technically doesn't count here.--Jasper Deng (talk) 04:33, 18 August 2012 (UTC)

This might be where you read both of those things [1]. 203.27.72.5 (talk) 04:32, 18 August 2012 (UTC)

I read that one on-wiki.--Jasper Deng (talk) 04:33, 18 August 2012 (UTC)

Well that could have been meitnerium, which cites the article I did when it says, "The oxidation state +9 might also be possible for meitnerium in [MtO₄]⁺". 203.27.72.5 (talk) 05:00, 18 August 2012 (UTC)

I specifically recall the iridium-based cation.--Jasper Deng (talk) 05:04, 18 August 2012 (UTC)

The paper W203 cites was also mentioned in two previous ref-desk discussions on this topic. DMacks (talk) 17:46, 18 August 2012 (UTC)

[2]. (I've also seen it before on WP, but, annoyingly, can't remember where right now.) Double sharp (talk) 12:53, 19 August 2012 (UTC)

Talk:Iron#Fe(VIII)? DMacks (talk) 14:59, 19 August 2012 (UTC)

Am I not too late to show up with another surprise? (There is no fundamental reason why an OS above +8 couldn't exist in a non-main block element. It's all about energy. Think of HgF4. It is very unstable, but existent. (although it also breaks a school rule, which is, in this case, that a truly (no Madelung exceptions) finished shell other than ns2 may not be broken down). Or Xe compounds (even though they don't break the octet rule, but again you can't correctly draw it with school-style Lewis dots). Even the masses before and after a chemical reactions don't match (E=mc2 :P). Note that none of first four periods elements can step over +7. For no fundamental reason -- just iron doesn't want to form eight bonds. Plus consider the SHE with several shells open at a time (they are complicated). The main problem, aside that the elements don't want to lose electrons (although they defend-- highest OS compounds are never ionic, so that the electrons are not completely away), is that you have to squeeze many fluorides around a single atom, it's hard. Using oxides (two bonds, twice the OS) is a good approach, but they may let you down and bond to themselves rather than the metal (like chromium pentoxide, which is actually "oxide diperoxide"). Sorry if I'm duplicating anything, but I want to make a more-or-less balanced reply (note I'm not a chemist, nor plan to ever be one, so if you're seriously into the idea, find one specializing one the stuff instead))--R8R Gtrs (talk) 22:48, 19 August 2012 (UTC)

How about Americium, is there potential? Plasmic Physics (talk) 02:40, 20 August 2012 (UTC)

Well, according to Americium for Am³⁺ → Am⁰ the potential is 2.08V, but for Am⁹⁺ → Am⁰ I have no idea. 203.27.72.5 (talk) 04:57, 20 August 2012 (UTC)

A ha, ha, and ha.

Addendum: ha. Plasmic Physics (talk) 10:27, 20 August 2012 (UTC)

Some speculation on high oxidation states on a forum – Cs(III), Fr(III), Ir(IX), Am(IX). R8R Gtrs also found this (speculation on high oxidation states of the period-6 transition metals, posted on Wikipedia talk:WikiProject Elements/Archive 11#Highest oxidation states of elements osmium through mercury) last year. Double sharp (talk) 10:02, 20 August 2012 (UTC)

Specialization related to identification of animal sounds

Is there any specilization dealing with identification of sounds by animals (in the context of animal husbandry). Who are the well known figures in this speciality area Would appreciate any help183.83.244.183 (talk) 07:57, 18 August 2012 (UTC)vsmurthy

There's bioacoustics (and the related ecoacoustics). Identification by sound is a large part of the work of bioacousticians (especially among ornithologists). I don't know of any subfields of those specializing in domesticated animals though, as the usual subjects are birds, marine mammals, fish, anurans, and insects. There's also zoosemiotics, the study of animal communication in general.-- OBSIDIAN†SOUL 10:18, 18 August 2012 (UTC)

Hi, I need help with this endocrionological equation

There is a link for a picture of it.

I have understood the more basic equations to it, but i have lost that one, and i have tried some times... it appears in chapter 1 of Greenspan's endocrinology textbook. please explain it to me, i must understand it. many thanks. 79.181.146.146 (talk) 09:44, 18 August 2012 (UTC)

To save others the trouble, here is the equation in question: ${\frac {[HR]}{[H]}}=-({\frac {[HR]}{K_{d}}})+{\frac {R_{0}}{K_{d}}}$

Given the (meagre) context you've offered, I would presume that H is hormone, R is receptor, and $K_{d}$ is their dissociation constant.

You can multiply both sides by $K_{d}$ to get a somewhat simpler expression. Then we know that, by definition:

$K_{d}={\frac {[H][R]}{[HR]}}$

The equation then becomes $[R]=R_{0}-[HR]$. This seems pretty obvious (receptor concentration equals original/total concentration minus what is bound).

Regarding what the original equation "means" - that would depend on what is known about a system (e.g. which variables are already known or measurable) and what is desired; however, you could make some guesses about what each term in the original expression means based on what I've said. BTW, is this homework? -- Scray (talk) 19:51, 18 August 2012 (UTC)

Ah, one more thing about how that equation might be useful. You might want to have a look at Scatchard plot, and consider that ${\frac {[HR]}{[H]}}$ is really the ratio of bound to unbound hormone, and $[HR]$ is the bound fraction. Now, if you compare your original equation to y = mx + b, can you see what you could learn from a Scatchard plot? -- Scray (talk) 20:02, 18 August 2012 (UTC)

Hello Scary, so much thanks for your deatiled explaination. it's not homework !. i just came across it at the library.. i have yet to do that comparison. first i need to make sure i understood you right: that, R is R0---which is the sum of the dissociation between H+R..?

btw, why should we divide :$K_{d}={\frac {[H][R]}{[HR]}}$ shouldn't it be the opposite?: $K_{d}={\frac {[HR]}{[H][R]}}$, ie: $K_{d}$ equals the HR complex divided by H+R?. thanks !. 79.177.146.177 (talk) 21:02, 18 August 2012 (UTC)

I did not say that "R is R0", nor that it is "the sum of the dissociation...". I meant to imply that $[R]$ is unbound receptor, and $R_{0}$ is the total receptor concentration, i.e. $R_{0}=[R]+[HR]$ (but I am not the one who was looking at the book - I am making inferences). For an explanation of the $K_{d}$ equation, have a look at Dissociation constant. -- Scray (talk) 21:14, 18 August 2012 (UTC)

What is John Money's intention?

In the definition of the evolutionary term "Phylism" (page 85) ? — Preceding unsigned comment added by 109.65.177.63 (talk) 10:24, 18 August 2012 (UTC)

Black hole = Center of mass?

I am just throwing out this intuitive idea , how about this:

Black holes are formed at the point where the center of mass would be for massive objects such as galaxy's and globular clusters.

The mass of the object causes the distortion of space/time at the point where the center of mass would be and hence a black hole (or perhaps only super massive black holes).

92.23.128.134 (talk) 11:14, 18 August 2012 (UTC)a-uk

The centre of mass may be a future black hole, but a black hole event horizon will not appear around the space that is empty. He potential energy will be lower at one of your masses. Graeme Bartlett (talk) 12:25, 18 August 2012 (UTC)

"He potential energy" = the energy only released by a male couch potato when his team scores a goal on the TV. StuRat (talk) 18:31, 18 August 2012 (UTC)

You may find the shell theorem interesting. As it shows, there isn't necessarily any gravitational field at the centre of an object. Black holes form because of a concentration of matter at a point, not because of matter distant from that point but centred on it. --Tango (talk) 13:54, 18 August 2012 (UTC)

According to the M-sigma relation there is a close correlation between the central bulge of galaxies and the black holes that form. An idea mentioned there is that the hole predates much of star formation, triggered by a "collapse of the central bulge".^[3] The hole is indeed formed by a distortion of spacetime, i.e. gravity. Wnt (talk) 14:19, 19 August 2012 (UTC)

Plant identification

Hi! Can anyone identify the plant in these photos? In the space of a couple months, it's taken over almost our entire garden. Wide Mid Close - Thanks very much! 77.97.198.48 (talk) 19:13, 18 August 2012 (UTC)

Possibly relevant: location is Scotland. 77.97.198.48 (talk) 19:18, 18 August 2012 (UTC)

It looks to me as if it may quite possibly be Himalayan Balsam (Impatiens glandulifera), a rather troublesome invasive species now found in parts of Scotland [4] If this is indeed the case, I wish you luck in getting rid of it. You may be occupied for some time. AndyTheGrump (talk) 19:57, 18 August 2012 (UTC)

That looks like a strong contender, thank you - although the photos I've found online seem to show serrated leaves, which are absent (certainly that I noticed, I will check again in the light tomorrow) from ours. Would that rule it out, or could it simply be a smooth-leafed variation? Thanks again. 77.97.198.48 (talk) 21:18, 18 August 2012 (UTC)

Actually, after a little more digging, we've come across Himalayan Honeysuckle which looks exactly like what we have, so I'm going to mark this one resolved. Thanks for setting us on the right path! 77.97.198.48 (talk) 21:30, 18 August 2012 (UTC)

That may not necessarily be good news either - Himalayan Honeysuckle is yet another invasive species apparently. It might be worth contacting the Scottish Environment Protection Agency, via one of their local offices (see here [5]) if you are still at all in doubt about the identification. I'm sure they'll be only too familiar with abominable Himalayan beasties invaders, and with other possibilities and will be able to confirm one way or another. If it is the Balsam or the Honeysuckle, your only consolation is that at least you haven't been infested with Giant Hogweed (Heracleum mantegazzianum), another invader that adds phototoxicity to the long list of reasons not to like it. Sadly, along with Himalayan Balsam, and Japanese Knotweed (which can swallow locomotives whole, as our article illustrates ), it was originally introduced to the British Isles deliberately for ornamental reasons. Not a good idea... AndyTheGrump (talk) 21:56, 18 August 2012 (UTC)

Resolved

It's hard to see how a plant awarded the AGM by the Royal Horticultural Society could be regarded as a garden pest! It spreads easily because the berries get eaten by birds and redistributed. All you need to do is pull it up if you don't like it. --TammyMoet (talk) 09:37, 19 August 2012 (UTC)

Opinion in the UK seems to be somewhat divided regarding the Himalayan Honeysuckle. In other parts of the world, it is unquestionably regarded as a serious invasive weed. New Zealand seems to have the worst problem, but the Australians don't appear to appreciate it either [6], and I doubt that de-weeding National Parks and mountain ranges by hand is practical. AndyTheGrump (talk) 18:54, 19 August 2012 (UTC)

If it's anything like Japanese knotweed, an invasive garden plant that's gone on the rampage in many parts of Europe, it's not quite as simple as "pull it up if you don't like it". I decided to expunge a clump of knotweed about 7 years ago. I spent a half-day digging it out and burning every fragment of the roots and the knotty rhizomes that I could find (moving them anywhere else is a criminal offence). I am still pulling up new shoots of the wretched stuff today (well Friday actually). Alansplodge (talk) 22:19, 19 August 2012 (UTC)

Ok, apologies Tammy, apparently you can "just pull it up" as long as you don't disturb the seed pods - see AndyTheGrump's link above. Alansplodge (talk) 17:59, 20 August 2012 (UTC)

Why the climate is not completely cyclic?

Hi,

Why the climate is not completely cyclic? I mean, why in one day in different years, there are different temperatures? Exx8 (talk) 21:52, 18 August 2012 (UTC)

The Earth's climate is the result of extremely complex interactions - the planet's annual trip around the sun certainly plays a big role, but there are just so many other factors involved that it just isn't reasonable to expect the temperature of any given point to be consistent from one year to the next. 66.87.127.70 (talk) 23:11, 18 August 2012 (UTC)

It's all the fault of those damned butterflies.[7] Clarityfiend (talk) 23:45, 18 August 2012 (UTC)

I cannot resist sharing this comic. --Mr.98 (talk) 00:26, 19 August 2012 (UTC)

Yes, tiny random events, like the proverbial flapping of butterfly wings, cause larger changes, eventually resulting in global changes in weather patterns. There are also other cycles, like the approximately 5-year el Nino cycle and the 11.2 year sunspot cycle which can affect the weather. StuRat (talk) 23:48, 18 August 2012 (UTC)

Do tiny events like that really cause global changes in weather patterns? One time events I can see, but changing the pattern of events seems a bit of stretch to me. I could be mistaken. 203.27.72.5 (talk) 00:26, 19 August 2012 (UTC)

You may be interested in Milankovitch cycles. In brief, even if the year were exactly 365 days long, the Earth is not in the same orientation every January 1st. Throw in small year-to-year variations in Solar brightness, the apparent chaotic nature of weather, weather effects of volcanoes, industry, etc... What you're left with is no reason to suspect that climate should be perfectly cyclical. Someguy1221 (talk) 01:42, 19 August 2012 (UTC)

• It is; the cycle is simply longer, on monkeys and typewriters scale. μηδείς (talk) 01:57, 19 August 2012 (UTC)

In addition to the good reasons mentioned above, climate is not even an abiotic phenomenon. Biogeochemistry plays a large role in determining how Earth's climate has changed across long time scales. SemanticMantis (talk) 02:30, 19 August 2012 (UTC)

August 19

Pressure increase on the ground due to an overflying plane

A plane of mass m flies at some altitude h (say h = 10 km) above the ground. The force of gravity acting on the plane is ultimately transferred to the ground, so the pressure at the ground will increase due to an overflying plane and this obviously depends on the position on the ground relative to the plane. The problem is then to compute this pressure increase from first principles. You can only simplify things by assuming that the plane is very far away from the ground. Count Iblis (talk) 03:40, 19 August 2012 (UTC)

Sounds like homework. The problem is not knowing how the pressure is distributed. If forced to guess, I'd go with a 45 degree cone with equal pressure applied to all the ground under it. Has anyone actually studied this to determine the true force distribution ? StuRat (talk) 04:04, 19 August 2012 (UTC)

The pressure quickly spreads out spherically. The mean free path of an air molecule, which moves at 1,000 km/h at STP is 10 cm. This conical notion seems to imply you are forgetting air is a gas. μηδείς (talk) 04:12, 19 August 2012 (UTC)

Spherically ? Do you mean hemispherically ? Certainly a plane doesn't increase the pressure above it. StuRat (talk) 04:15, 19 August 2012 (UTC)

Yes, it does, there is nothing to constrain it. Consider a sonic boom. It doesn't just travel downward or in one direction. When you blow up a balloon, it does not expand only on the surface opposite your mouth. You are imagining a gas as if it were a pile of sand with a critical angle of repose. The atmosphere consists of particles bouncing off each other in random directions at 1,000 km/h at STP. Any change in pressure (and actually there is no real net change in pressure except the from the heat generated by the flight, since the difference in pressure above and below the wing is quickly neutralized as the plane passes) is rapidly transmitted in every direction. μηδείς (talk) 04:27, 19 August 2012 (UTC)

It can be useful to think of the atmosphere as an ocean of air. Airplanes, especially those flying at high speeds create a "wake" in the air just as boats do on a pond. And if another traveling object hits that wake, it can cause it to "bounce" in the unstable substance. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:00, 19 August 2012 (UTC)

Yes, but the wake (of turbulence, not pressure) soon dissipates, and is not a cone of pressure beneath the airplane. μηδείς (talk) 05:06, 19 August 2012 (UTC)

I think I see the difference. However, I've been on planes when we got bounced around a bit, and the pilot said we were in the wake of another plane. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:52, 19 August 2012 (UTC)

Yes, wake turbulence is a very real thing, but it is different to the equal and opposite reaction to the lift, which is what the OP is asking about. --Tango (talk) 10:45, 19 August 2012 (UTC)

Fascinating question with very real implications, and very difficult physics to contemplate. Every time I land my little Citabria at San Jose International Airport, the tower warns me to watch out for vortices and wake turbulence from the big 737s on every single approach - even if I'm the only aircraft around - just in case the vortex from the last jet is still "floating around" in the air. The textbook-solution (Chapter 7 section 3 of the AIM) has some nice cartoon diagrams of persistent wake and vortex effect. 7-3-4 discusses sink-rate of persistent vortices - in other words, how long until the wake "hits" the ground. So, that's how to solve it not from first principles, but in a way that provides pilots with useful information.

From first-principles, the assumption is invalid: air is compressible, so the dynamic pressure that creates lift near the aircraft need not ever propagate to the ground. It could aerodynamically convert to another form of energy, such as compression-heating. After the aircraft passes, it could return to its original state. Energy is conserved, and momentum is conserved, but there is no law of conservation of pressure, temperature, or force. In an ideal, perfect, skin-frictionless system with perfect laminar flow, the air should flow smoothly around the aircraft, and no energy need be lost to propagating a pressure wave away from the aircraft surface.

In the vortex wake turbulence case, the air flow is not propagating as a pressure wave - it is a turbulent, convecting effect. For comparison, the sound of the engines is propagating as a pressure wave, at much higher frequencies. It would be interesting to compare total energy or power in each propagating mode. I suspect more energy is propagating as low-frequency convecting turbulence, rather than as an acoustic pressure wave. NASA has studied wake turbulence and the vortex effect very thoroughly - there's a classic photo that is now a featured picture - aircraft vortex effect. To compute these sorts of things from first principles, as the OP requested, is nearly impossible: but that's how we derive the basic laws of air flow such as Navier Stokes. I think the problem is the assumption that the dynamic air motion can be expressed simply: but in an enormous mass of thermally-inhomogeneous, convecting air, simple pressure-waves are so unphysical as to be misleading. Suffice to say, the aircraft wing loading is sustained by the dynamic pressure of the air close to the aircraft; and that air is supported by the dynamic pressure of the air near it, ... and ad infinitum, all air that ever contacts any other air exchanges energy and momentum through complicated aerodynamic processes. The speed of propagation of each effect is different: there is an effective wave speed for pressure, for shear/vortex propagation, for thermal conduction, and so on. Each process conveys some of the energy, and some of that energy translates into transient, dynamic pressure. Because air is compressible, it's meaningless to talk about only the pressure wave propagating. You must consider the other aerodynamic effects. Nimur (talk) 16:00, 19 August 2012 (UTC)

Pressure always acts in all directions. That's the main thing that distinguishes between it and other forces. Hold you hand out in front of you, flat to the ground. The mass of the column of air above it is about 8kg and the weight of that is pressing down on your hand. That's the air pressure. You can hold your hand up easily, though, because there is an equal pressure on the bottom of your hand and the forces cancel out. While the pressure on the top of your hand can be thought of as the weight of the air above it, the pressure of the bottom is a little more difficult to understand - it's caused by the rest of the atmosphere pressing down on the air next to your hand, which pushes on the air under your hand, which pushes up on your hand. --Tango (talk) 10:45, 19 August 2012 (UTC)

The problem with the "cone" model is that the force won't immediately be transmitted to the ground, but will be transmitted as some sort of slow pressure wave. The problem is a bit similar to blowing briefly at the far wall of a room - where will the breath impact? - except that because the plane has since moved the area "supporting" it will be far behind it when it reaches the ground. A difficult and interesting question. Wnt (talk) 14:27, 19 August 2012 (UTC)

As pointed out above, a plane's downwash spreads outward and dissipates rapidly. When helicopters and planes fly low enough, this downwash interacts with the ground (see the article on ground effect (aircraft) for instance). With helicopters their downwash can create vortex rings of air that are dangerous, because the air mass in which the copter is in starts to descend rapidly. Air vortex cannons can create these vortex rings which can hit targets such as the ground, and these cannons can be as simple as thumping the bottom of an empty one-gallon milk jug. Modocc (talk) 15:19, 19 August 2012 (UTC)

Spreads outward, yes; dissipates, somewhat, at least in terms of energy - but one thing it cannot do is dispose of its downward momentum, except by impacting something to transfer it to. Wnt (talk) 15:43, 19 August 2012 (UTC)

The downward momentum is quickly transferred and scattered amongst a large number of molecules though, adding a nearly insignificant downward movement to the air in a much larger surrounding atmosphere. The entire Earth moves too, eventually, but that happens every time I get out of bed. Also, the energy of the downwash is still dissipated, thus when it has no more energy, it no longer transfers momentum to the atmosphere. -Modocc (talk) 16:20, 19 August 2012 (UTC)

This is related to that old thought experiment/joke of getting a van full of birds over a bridge that won't take the weight by making sure enough of them are flying at any given time. It doesn't work because the lift on the birds from their wings has an equal and opposite force on the floor of the van. For the van, it's a closed space so you know all the force will go to the floor of the van. For a plane, it isn't a closed space so the force can be much more spread out. It has to still exist, though - there are no exceptions to Newton's third law. --Tango (talk) 17:13, 19 August 2012 (UTC)

Sure it exists, but its certainly important here to observe which objects this force is transferred to and what significant effects it can have with respect to other influences. In this case, with increases in the region affected, there is increasing mass involved thus there is less possible motion or speed. Moreover, one has to consider too that if I am getting out of bed or flying about, no net movement of the Earth or the atmosphere will occur if I have a twin doing the exact same thing, but creating an opposing force. In fact, such an equilibrium state and the observed lack of net influence is typical. Modocc (talk) 17:41, 19 August 2012 (UTC)

So far as I know, transferring momentum always requires energy, but the amount of energy can get less and less. (Hence the "somewhat" I used above) For example, a photon can carry a quantum of angular momentum no matter how low frequency (low energy) it is, and as far as I know this doesn't set any minimum energy that photons can have. Likewise the momentum of a speeding bullet can be transferred to a stinging bruise behind a bulletproof vest, to the relatively mild force the person thus shot exerts on a wall to maintain his balance. Wnt (talk) 18:37, 19 August 2012 (UTC)

When the plane's trailing downwash of air pressure has transferred its energy, the downwash seizes to exist. Its mass-energy and momentum is therefore conserved by the more massive mass-energy and momentum of the atmosphere and the Earth. --Modocc (talk) 19:17, 19 August 2012 (UTC)

Yes, that "chickens in a sealed truck" thought experiment is an applicable one. Let's extend that by imagining a truck which is miles long, wide and high, with an airplane inside. Does the total system become lighter when the plane is in flight ? Obviously not. Therefore, there must be some downward force to provide the equivalent of the weight of the plane, at those times. I suggest that this is caused by higher pressure on the floor of the truck than on the roof. This, however, contradicts some of the statements above, such as the pressure dissipating evenly (above and below), or changing into heat. StuRat (talk) 20:44, 19 August 2012 (UTC)

I believe what was meant above was that the plane's contribution to the pressure on the ground, which is force per area, is not going to be significant because it is spread over a wide area. -Modocc (talk) 21:39, 19 August 2012 (UTC)

All the atmosphere's pressure is eventually transfered to the earth's surface, over the entire earth. Since the atmosphere has no lid, it is simply the atmosphere's total weight which presses on the earth. But air pressure is not the same as the coherent directional movement of air. Adding a plane of a certain weight to the atmosphere is just like adding an equivalent weight of air to the atmosphere. If a plane is actively flying, it is exerting a downward force on the air below its wings which may translate to the ground as wind, if it is close enough. But an airplane within a giant space will simply create circulating winds that will have no coherent direct action on the surface below it.

Any increase in air pressure within a sealed container will exert just as much lifting force on the roof as it will depressing force on the floor. An airplane within an infinitely giant balloon would cause the balloon to expand, not to sink. Sustained flight within too small an enclosed area is simply not possible because the air will become turbulent and circulating currents will become harder and harder against which to generate lift. Within an infinitely large area you are dealing with just pressure--on the earth this is countered eventually by downward force--in an enclosed area it is countered by balanced increasing pressure on all surfaces in all directions. μηδείς (talk) 22:44, 19 August 2012 (UTC)

For the most part I agree with you, because being trapped in a balloon, a bee or plane won't alter the balloon's buoyancy which is fixed, but the internal weight distribution can change with flight. Thus, when a plane takes off, it adds its weight to the atmosphere, the contribution of this force (its mass*g) being small... and if its within a giant balloon the balloon expands... which is from an increase in air pressure from the additional energy of the plane's propellants. When the plane lands, its mass-energy is correspondingly lighter and the atmosphere heavier. Its not all that difficult to hover within fairly confined spaces (think of a nearly buoyant swimmer treading water by pushing it downward) and wings produce pressures and partial pressures creating the winds of the downwash that, in turn, produce pressures, like sound waves and pressures against adjacent air masses as well as obstacles, but the essential impulse is usually rapidly absorbed by the surrounding large volume of air in a relatively short distance. Thus, the question of an atmospheric pressure change due to either the weight of the plane or due to the weight of the absorbed energy from a great altitude... seems to be similar to asking how much does the salinity of an ocean basin differs if one adds a grain of salt and ignores all the other contributions to its saltiness. That said, perhaps some tangible numbers, as the OP has requested, would clarify that this is indeed the case. -Modocc (talk) 03:58, 20 August 2012 (UTC)

Suppose the plane flies around for a long time near the north pole. The gravity exerted by the plane will cause the Earth to be attracted to it with the same force as it attracts the plane, and over time, the Earth will fall constantly northward, accumulating a great deal of momentum (even if it is not particularly visible) in that direction --- unless, that is, some force presses back against the Earth with an equivalent force to that gravity. Now that press-back is not a universal inward force on the entire spherical surface of the Earth, because that wouldn't shove the Earth back in one direction away from the plane. It is a force that remains aligned with the position of the plane, transmitting its weight to the Earth somewhere vaguely below it, in such a way as to add up to precisely the right force to keep the Earth from being pulled by its own bootstraps in any particular direction simply because a plane is in the air. Wnt (talk) 04:16, 20 August 2012 (UTC)

That's about right, for the Earth's momentum is conserved and does not and cannot change, and its precisely the force of the impulse that is involved, for it is absorbed, shoving the Earth and its atmosphere back, including regions above the plane, negating the gravitational pull. Without the Earth's gravity, the impulse would cause the Earth to be pushed southward. Again, an impulse that begins at a high altitude or even a modest altitude, is a comparatively very small force that spreads out over a very large area and becomes essentially absorbed and blended with other more significant interactions, for I think its likely to be a smaller influence than measurable localized barometric changes. We need to pin some numbers on this though. Modocc (talk) 07:01, 20 August 2012 (UTC)

Ah, aerodynamics. The last remaining branch of classical physics where nobody can provide a coherent answer, but everyone thinks the answers are obvious except those who've actually studied the subject. But yes, ultimately a flying aircraft's weight is transferred to the ground via increased pressure. Take my word on it, I'm not an expert. ;)

As Modocc said, tangible numbers would help here. I'd start by looking into ground effect, where the pressure changes are going to be more obvious. AndyTheGrump (talk) 04:13, 20 August 2012 (UTC)

Yes, "Ground effect", or just observing a low-flying plane or helicopter from just below, shows the force on the ground. Tango implies that pressure is always the same in all directions, and this is true in a static fluid, but is not true in a moving fluid such as the atmosphere. For a high-flying aircraft, the weight of the machine is ultimately exactly balanced by movement of air over a wide area, transferring an equal and opposite force to the surface of the earth on the side of the aircraft. By the time any pressure changes have been propagated to the far side of the earth, the aircraft will have landed (or completed several subsequent flights). As Andy implies, aerodynamics is very different from static pressure. When RAF planes fly low over my roof, I definitely feel the downward pressure! Dbfirs 11:58, 20 August 2012 (UTC)

Distance of galaxies from Earth

How many light-years from Earth would a congalaxy have to be if I made it a galaxy that hadn't been discovered by Terran astronomers yet? Subliminable (talk) 05:48, 19 August 2012 (UTC)

What is a congalaxy? Someguy1221 (talk) 06:01, 19 August 2012 (UTC)

This link should explain: [8] Subliminable (talk) 06:10, 19 August 2012 (UTC)

Working in proper lengths, the most distant observed galaxy-candidate is ~30 billion light years away (see Observable universe#Most distant objects). There's an extra ~17 billion light years of radius in the observable universe left to work with. Someguy1221 (talk) 06:24, 19 August 2012 (UTC)

But what if I wanted to create a galaxy that was 600 million light years away? Would there be a realistic chance that science hadn't discovered such a galaxy yet as of 2012? Subliminable (talk) 06:29, 19 August 2012 (UTC)

There are (estimated) over 100 billion galaxies in the observable universe, and the vast vast majority of them have never been identified. At 600 million light years you are probably safe. Someguy1221 (talk) 06:34, 19 August 2012 (UTC)

Or you could place it so it couldn't be discovered. It would have to be hidden somehow. It could be behind a closer galaxy, or blocked by something within our own galaxy, like a gas nebula. StuRat (talk) 06:37, 19 August 2012 (UTC)

On Stu's note, you could put it on the far side of the Milky Way's center, relative to Earth. Although that's not a position it could maintain, it would easily make it unobservable for the relatively brief period of time we've been using telescopes. Someguy1221 (talk) 06:41, 19 August 2012 (UTC)

We are still discovering galaxies right at our doorstep, e.g. Ursa Major I Dwarf at 330000 light years. Youjust have to make them small enough. --Wrongfilter (talk) 07:32, 19 August 2012 (UTC)

We discover distant galaxies by picking a very small region of the sky and looking at it very closely. That means most galaxies haven't been discovered because they aren't in one of the regions we've looked at. --Tango (talk) 10:47, 19 August 2012 (UTC)

Electric Potential

Consider a circular disc of radius $a$ that lies in the xy plane and surface charge density (in cylindrical coordinates $(s,\phi ,z)$): $\sigma (s,\phi )={\frac {\alpha }{s}}\cos \phi$. Calculate the potential at a point $h{\hat {z}}+r{\hat {s}}$.

This is my calculation:
The electric field is $\int \int _{A}{\frac {\sigma dA}{(h^{2}+(r-s)^{2})^{\frac {3}{2}}}}((r-s)\cos \phi ,(r-s)\sin \phi ,h)$
$=\alpha \int _{0}^{2\pi }\int _{0}^{a}{\frac {dsd\phi }{(h^{2}+(r-s)^{2})^{\frac {3}{2}}}}((r-s)\cos ^{2}\phi ,(r-s)\sin \phi \cos \phi ,h)$
$=({\frac {-\alpha \pi }{(h^{2}+(r-a)^{2})^{\frac {1}{2}}}}+{\frac {\alpha \pi }{h}},0,{\frac {2\pi (a-r)\alpha }{h(h^{2}+(r-a)^{2})^{\frac {1}{2}}}})$. Now, to calculate the potential: $-\int _{\infty }^{h}{\frac {2\pi (a-r)\alpha }{z(z^{2}+(r-a)^{2})^{\frac {1}{2}}}}dz$. Widener (talk) 10:51, 19 August 2012 (UTC)

Do you have a question? -- Scray (talk) 12:07, 19 August 2012 (UTC)

He wants us to check his method. Plasmic Physics (talk) 12:11, 19 August 2012 (UTC)

Yeah. Widener (talk) 12:35, 19 August 2012 (UTC)

My first question is, is the separation vector right, id est $((r-s)\cos \phi ,(r-s)\sin \phi ,h)$ because $h{\hat {z}}+r{\hat {s}}$ is not even really a single particular vector in $\mathbb {R} ^{3}$ is it. That's a bit confusing. Widener (talk) 12:34, 19 August 2012 (UTC)

You're right, the separation vector is not correct. I don't understand either what is meant by ${\hat {s}}$ since the direction of that unit vector depends on the $\phi$ coordinate of the point where the potential is being calculated and it seems to me that this coordinate was not given. Dauto (talk) 22:07, 19 August 2012 (UTC)

Does it help if I mention that $r$ is small? Widener (talk) 23:58, 19 August 2012 (UTC)

Is this stone is natural or human made?

குத்துக்கல் வலசை பெருங்கல்

This local people said that their ancestors worshiped this rock. They told this is a natural formation. But after saw the bottom side of the rock I think this is human made. Can any one guess this period? and artificial or natural? To see the bottom side of the rock exactly visit this blog.

http://fromthenmaduraitotenkasi.blogspot.in/2012/08/1.html

http://4.bp.blogspot.com/-ipo2kpQm7Ck/UC-wuyspMsI/AAAAAAAAAF8/JbT9pZqvkTM/s1600/IMG_0067.JPG

--Tenkasi Subramanian (talk) 17:42, 19 August 2012 (UTC)

It's natural; see balancing rock. μηδείς (talk) 18:17, 19 August 2012 (UTC)

I already saw this balancing rocks. http://wowpics.in/amazing-pics/top-10-unbelivable-balanced-stone-around-the-world/

But after see the bottom side only I confused. Did u c the bottom side of the rock? see this link?

http://4.bp.blogspot.com/-ipo2kpQm7Ck/UC-wuyspMsI/AAAAAAAAAF8/JbT9pZqvkTM/s1600/IMG_0067.JPG

Can u say what type of bond is made between floor and rock?--Tenkasi Subramanian (talk) 18:23, 19 August 2012 (UTC)

They're both just rock - by which I mean that the rock is continuous, its not actually balanced. Mikenorton (talk) 18:28, 19 August 2012 (UTC)

You're saying it's a hoodoo? μηδείς (talk) 22:18, 19 August 2012 (UTC)

No, there's no hard caprock here, just a layer that's slightly less resistant to erosion, which forms the narrow part of the rock. Still pretty strong rock though (compressive strength at least) to take that load. Mikenorton (talk) 07:16, 20 August 2012 (UTC)

Looks natural to me but could have been enhanced by people? Really hard to tell without examining it for tool marks etc... PatHadley (talk) 09:50, 20 August 2012 (UTC)

Ozone Dangers

Is it a fact that just 5% of Ozone if mixed with the atmosphere can cause all life-forms to vanish ? Also is it true that if ozone is cooled up to -200 ^o, C liquidized, and put into a breakable glass ball, if blasted like a grenade can turn a man into glass? 124.253.89.68 (talk) 17:48, 19 August 2012 (UTC)

Some one told that Ozone is O3 (Oxygen). I think that's not harmful.--Tenkasi Subramanian (talk) 18:29, 19 August 2012 (UTC)

Please don't answer science desk questions based on what you 'think'. Check your facts:

"Even very low concentrations of ozone can be harmful to the upper respiratory tract and the lungs. The severity of injury depends on both by the concentration of ozone and the duration of exposure. Severe and permanent lung injury or death could result from even a very short-term exposure to relatively low concentrations." [9]

I suggest you both read our Ozone article. As for the 'ozone grenade', where did you see that? AndyTheGrump (talk) 18:34, 19 August 2012 (UTC)

Yes, as stated above, ozone is harmful if breathed in, but it's also quite helpful in blocking UV light in the ozone layer. So, we want lots of ozone in the air, just not down here where we would breath it. StuRat (talk) 20:24, 19 August 2012 (UTC)

Just to clarify, we want lots as in ~5-10ppm, not ~5%. 203.27.72.5 (talk) 03:32, 20 August 2012 (UTC)

Given it's half-life of 30 minutes in the lower atmosphere, I think fish in the sea would be safe and maybe some or most trees would survive. But it's highly corrosive and has a IDLH of 5ppm, making hydrogen cyanide with it's value of 50ppm seem quite benign in comparison. Found some rumours about India’s glass man, with a skeleton visible inside. Liquid ozone can detonate, but to turn a man into glass, you'd need a man made of silica to begin with ... Ssscienccce (talk) 23:23, 19 August 2012 (UTC)

Glass has more than one meaning, and flash-frozen flesh meets the most general definition. μηδείς (talk) 23:29, 19 August 2012 (UTC)

I did some back of the envelope calculations using the following data; density of liquid O₃ = 1.352g/mL [10], heat capacity of liquid O₃ ~ 0.45cal/gK[11], ozone boils at 161K, the latent heat of vapourization for O₃ = 75.59 cal/g [12], and the heat capacity of O₃ gas = 0.195 cal/gK [13]; and assumed that the grenade is a sphere of radius 5cm, it starts at 90K, the man weighs 100kg, his heat capacity is the same as water, his body temperature starts at 311K, to be considered "turned in glass" his whole body must be equal to or less than 273K, the grenade only cools the man and thermal equillibrium is reached instantly, and no exothermic oxidation reactions occur that would heat the system. 91542 calories are required to bring the grenade to 273K, and that's enought to cool 100000g by 0.91542K for a final temperature of about 37C. So, no this isn't possible just by flash freezing. If only his surface must be cooled, than you'd get a bit further with the flash freezing argument, but then you'd want to start correcting for the other generous assumptions made above. 203.27.72.5 (talk) 01:03, 20 August 2012 (UTC)

Agreed, vitrification is possible, but not with a missile any man could heft in normal conditions. Better to use a hose. μηδείς (talk) 03:38, 20 August 2012 (UTC)

smell vs taste

Why does tea smell wonderful when dry but taste bitter once made? (Please don't digress into overbrewing tea etc - I'm talking about the correctly made stuff.) Ta, 184.147.128.34 (talk) 17:51, 19 August 2012 (UTC)

Tannins. --jpgordon^{::==( o )} 18:14, 19 August 2012 (UTC)

Coffee is the same way. And new tires smell good too, but I don't recommend eating them. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:49, 19 August 2012 (UTC)

Tannin#Drinks with tannins seems to disagree with you as far as coffee having much for tannins. BigNate37_(T) 19:57, 19 August 2012 (UTC)

So, tannins are bitter, but don't have a particularly bitter smell. I've found that herbal teas (tisanes) often contain fewer tannins, if any, so aren't as bitter, since they don't contain any real tea. This is good, since it allows me to drink them without sweeteners, either real or artificial. StuRat (talk) 20:21, 19 August 2012 (UTC)

Of course it's all completely subjective, I actually think the taste of straight tea is also wonderful, just like the smell. I don't like tea with sugar or milk added to it and I like it brewed quite strong. But I do occasionally enjoy a tea with lemon and honey, served hot on a cold day or cold on a hot day. Vespine (talk) 23:06, 19 August 2012 (UTC)

To actually comment on the question, I think it's just because smell and taste receptors are actually quite different in some fundamental regards. Even though a lot of the time they seem to compliment each other, like a lot of fruit smells precisely how it expect it should taste, but in other cases, like salt for example doesn't really have much of a smell at all. You can basically tip a cup of salt into a pot of soup and it won't smell much different, but if you tasted it, it would be completely inedible. Vespine (talk) 23:14, 19 August 2012 (UTC)

When I was kid, my brother baked brownies once. I first noticed when I smelled a beautiful intense aroma of vanilla wafting through the house. I came out into the kitchen to find out what he was doing and I asked him how much vanilla essence he put into the mix. He said that the recepie called for a cup but we didn't have that much so he just emptied the 50mL bottle that we had into the bowl. I had a look, and it actually called for a teaspoon. Needless to say, the brownies were probably the most bitter thing I've ever tasted. The look on his face when he bit into one of his creations was priceless. 203.27.72.5 (talk) 23:23, 19 August 2012 (UTC)

You need to distinguish between taste, flavour, and aroma. When it comes to taste, we're talking about what your tongue detects, which isn't as basic as once thought (and doesn't involve that stupid tongue map), but is a lot more basic than smell. The main tastes are salty, sweet, bitter, sour, umami, with probably a few more that we don't really discuss much. These are tastes, not smells, so you detect them with your tongue: you might guess based on past experience that something that smells of strawberries will taste sweet, but if you're drinking a fruit tea your tastebuds will be disappointed. You cannot smell how something will taste, beyond extrapolating from past experience. Bitter is a taste, not a smell.

When we actually eat something, we experience a flavour which is a combination of the taste and the smell/aroma. Because your nose and mouth are connected, you can smell the thing you are eating. When you drink a cup of tea, you taste the bitterness of the tannins which really shouldn't be much, if you're brewing the particular tea for the time it should be brewed for as well as experiencing the complicated combination of aromas from the tea that you could smell without drinking it: this combines to give a characteristic flavour.

When we add artificial flavourings to food, these are aromatic compounds that make the food smell nice, affecting the flavour: altering the taste involves much more basic things, like altering the amount of salt, sugar, fat, caffeine, etc, which also alters the flavour. A strawberry has a different flavour to a peach because it smells like a strawberry: it has different aromatics. Both fruits taste sweet. 86.157.148.121 (talk) 13:07, 20 August 2012 (UTC)

Just a silly story just in relation to how smell and taste are different, you mention fruit tea and I know exactly what you are talking about, but even more extreme example was this liquid fruit soap that I bought once which smelled exactly like delicious apples! But indeed tasted just like soap. Vespine (talk) 00:28, 21 August 2012 (UTC)

Thank you 86.157.148.121 that was a great answer; I get it. 184.147.128.34 (talk) 09:16, 21 August 2012 (UTC)

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: [14]. 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 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)

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.[15] 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.^[16] 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: [17]. 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): [18]. 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)

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 [19] [20]. 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)

August 21

Sticky Stuff Remover chemical identity

According to my online search, "Sticky Stuff Remover", for removing labels, has one active ingredient: CAS number 64742-47-8 - is this a mix of more than one chemical? Can it be obtained more economically in another form than "Sticky Stuff Remover"? --2.97.21.248 (talk) 02:39, 21 August 2012 (UTC)

Most adhesives are oil soluble, so just about any oil will work. WD-40 works, but, if you want something more pleasant smelling, try peppermint oil. Be careful not to get it on plastic, though, as it may also dissolve that. StuRat (talk) 02:41, 21 August 2012 (UTC)

CAS 64742-47-8 is a light petroleum distillate, so it's a mixture of low molecular weight hydrocarbons from crude oil. Apparently it's also sold as jet fuel , so I imagine that would be cheaper since you could buy it by the gallon. 203.27.72.5 (talk) 02:46, 21 August 2012 (UTC)

Somehow I doubt if the corner gas/petrol/filling station has it. StuRat (talk) 02:47, 21 August 2012 (UTC)

(edit conflict) Google turns up CAS number 64742-47-8 as "Hydrotreated light petroleum distillate" or other similar names. Here is one MSDS for it: [21]. It is basically hydrogenated kerosene, that is middle-weight hydrocarbons (say 8-16 carbons) which have been treated with hydrogen to remove any unsaturation (double/triple bonds). --Jayron32 02:50, 21 August 2012 (UTC)

Remember, the inactive ingredients make a difference too. The active ingredient is probably pretty dilute, and using it pure could damage paints and plastics. Given the answers above, it probably works about the same as using gasoline as a solvent. Unless you're looking to go through huge amounts of it, you're probably just better off shopping around for a cheaper off-brand version. Acetone-base nail polish remover also does a pretty good job with soft adhesives without being strong enough to damage most surfaces. 209.131.76.183 (talk) 14:08, 22 August 2012 (UTC)

Yea, but who wants to breath acetone fumes ? StuRat (talk) 19:51, 22 August 2012 (UTC)

Acetone fumes are probably no worse for health than petroleum distillate fumes. And the assumption that the active ingredient is dilute is in this case totally wrong. The product is essentially 100% hydrotreated light petroleum distillate [22]. 203.27.72.5 (talk) 21:00, 22 August 2012 (UTC)

Seems nasty to me: http://www.collectioncare.org/MSDS/Acetonemsds.pdf. I'll stick with peppermint oil, which is actually pleasant in small quantities. StuRat (talk) 21:14, 22 August 2012 (UTC)

I find butter works quite well for removing that annoying tacky residue from labels (and, ironically enough, from the gunk that ECG electrodes leave on your chest). Tonywalton ^Talk 23:02, 22 August 2012 (UTC)

Peppermint oil and butter fumes would certianly be less hazardous to your health than any synthetic or petroleum based organic solvents (though butter probably causes more deaths :P). With regard to acetone compared to the Sticky Stuff Remover, the MSDS toxicological information I have from my ChemAlert database gives:

• "Irritant. Over exposure may result in irritation of the nose and throat, coughing and headache. High level exposure may result in nausea, dizziness and drowsiness." for Sticky Stuff Remover inhalation and,
• "Irritant. Over exposure may result in irritation of the nose and throat, coughing, nausea, vomiting, weakness and headache. High level exposure may result in dizziness, drowsiness, incoordination and unconsciousness." for Acetone.

Unfortunately, there's no LC50 data for the Sticky Stuff Remover for comparison, but the acetone has LC50 (Inhalation): 44000 mg/m³/4 hours (mouse) which is quite high really. 203.27.72.5 (talk) 23:13, 22 August 2012 (UTC)

What is a Gaussian belt?

I ran across the term Gaussian belt in the Radio source SHGb02+14a article. Cursory Google searches turned up a few examples of the phrase in astronomical contexts. Is it related to spectral width? Thanks. Braincricket (talk) 03:39, 21 August 2012 (UTC)

It may be listed at List of things named after Carl Friedrich Gauss, but under a different name. Seriously, that dude has way too much stuff named after him. --Jayron32 04:58, 21 August 2012 (UTC)

A full-text search on ADS yields a single scientific paper with the phrase "gaussian belt" and it's not relevant to this radio source. As far as I can see, the phrase in the article is meaningless. I've commented it out until someone provides a reference or an explanation what it's supposed to mean. --Wrongfilter (talk) 10:26, 21 August 2012 (UTC)

orchid

can anyone tellme the name of this orchid??? http://en.wikipedia.org/wiki/File:Small-orchids.jpg

thanks 04:29, 21 August 2012 (UTC)Iskánder Vigoa Pérez — Preceding unsigned comment added by Iskander HFC (talk • contribs)

It's a Philippine ground orchid, Spathoglottis plicata. I have a picture of one in my backyard. :) -- OBSIDIAN†SOUL 04:49, 21 August 2012 (UTC)

Too bad you only have a picture of one in your backyard. The actual flower would be even prettier. :-) StuRat (talk) 04:52, 21 August 2012 (UTC)

Flowers wither, pictures are forever! ...and don't need watering. ;D -- OBSIDIAN†SOUL 06:35, 21 August 2012 (UTC)

Estimate altitude from environmental conditions

I have pressure in torr, temperature in C and relative humidity. Is there a standard way of estimating an altitude from this information? Barometric formula, Atmospheric pressure and International Standard Atmosphere all have good information, but not quite what I'm looking for. I'm going to look around the office to see if we have a copy of the ISO spec for the ISA. Otherwise it's looking like I may have to derive it myself. 209.131.76.183 (talk) 12:41, 21 August 2012 (UTC)

Formulas for estimating altitude are very fuzzy and tricky. The spherical cow approximations used in most calculations assume that the atmosphere is universal, constant, and unchanging: that is that there is a consistant set of atmospheric conditions whereby one could assume that altitude and air pressure are closely enough related to generate reliable data. That's how an altimeter works: it measures air pressure, assumes that surface air pressure is always the same value (it isn't) and that pressure decreases in a predictable way with altitude (again, if it does, it only does so in a very rough way). You're likely to be accurate to within a few hundred feet: for planes that's usually good enough to avoid hitting a mountain, as long as you've got enough of a buffer in your flight pattern, but we're still talking about an uncertainty of several percent, especially for smaller heights. Conceptually, what you're asking about is the correction between density altitude, pressure altitude, and actual altitude: technically feasible, as the density of air is related to the humidity and temperature (see Density of air for calculation) and air pressure is closely related to density. That density of air article has information on how humidity and temperature are used in calculating altitude. --Jayron32 12:56, 21 August 2012 (UTC)

The International Standard Atmosphere and the American Standard Atmosphere both assume the atmosphere consists of dry air so they won't be of any help if you want to use relative humidity to help fix an altitude. Dolphin (t) 13:14, 21 August 2012 (UTC)

I think I'm just going to throw out the temp and RH readings - looking more into how this is being used, I'm basically trying to simulate the output of a Kft altitude sensor that works entirely on pressure. Since the output I'm trying to duplicate doesn't care about temp and humidity, neither do I. I'll look for references on pressure to altitude, but if I don't find anything useful I'll take a stab at reversing the piecewise formula in Barometric formula. 209.131.76.183 (talk) 13:20, 21 August 2012 (UTC)

Mass of Thought

When I learn something new or remember an event, the information is stored in my brain. Does that information have mass?165.212.189.187 (talk) 13:38, 21 August 2012 (UTC)

Your body as a whole will slightly lose mass when forming a thought or memory, as it takes work to do so. Not sure about your brain specifically, though. Goodbye Galaxy (talk) 13:58, 21 August 2012 (UTC)

Reminds me of this Dilbert strip. AndrewWTaylor (talk) 15:04, 21 August 2012 (UTC)

There is a physical component of memory (see Memory#Cognitive_neuroscience_of_memory), but you aren't adding new mass when you learn new things, I don't think. The physical basis of memory — how you get from an experience to an encoded set of neurons — is still a very nascent field of study, as I understand it. There's no doubt there's a physical basis, but it's unclear to me whether talking about that in terms of mass makes sense, except in the obvious sense that all things to do with your brain do have physical mass. The way I picture it, which is not especially scientific (and is a hash derived from various sources, particularly Antonio Damasio) is that memory is more like a rattling of electrical charges through an existing structure, and the more you do certain things, the stronger certain pathways get. So you might imagine the brain as a cluster of special wire where the more you use them, the easier they become to use. The wires themselves are not added or moved — it's solid state, more or less — and what you're doing is making some pathways become more used than others. "Used" here means the sending of electrical/chemical signals through them. Or something like that. Perhaps others will have better ways to explain such a thing. --Mr.98 (talk) 15:13, 21 August 2012 (UTC)

OK, well does information in general have mass? I am thinking more along the lines of the information paradox of black holes argument.165.212.189.187 (talk) 15:34, 21 August 2012 (UTC)

As far as I know, from the age of three (?) we lose nerves every single day of our lives, so the brain should get lighter instead of heavier. Information is not stored in the brain as a physical entity, it is more like a connection. "The information is stored in my brain" is basically not correct. "The information can be recreated by my brain" would be a better way of phrasing this. Lova Falk talk 16:01, 21 August 2012 (UTC)

A connection is a physical entity. (It is not a non-physical entity.) --Mr.98 (talk) 16:09, 21 August 2012 (UTC)

Information is not a physical thing — it is better thought of as an event. It often is instantiated as a thing, but that is not its true nature. Consider a simple situation: I am signaling to you that I have arrived at my destination by flashing a laser at you. I've transmitted a bit of information. You might say, "well, you did shoot photons at me, and those are things." Indeed! (And note that we have there used massless things.) But if there had been an uninterrupted stream of photons, and I stopped them, now I'm signaling you with a lack of a thing. Thinking of information as a "thing" is just misleading — what matters is not whether a thing has been sent to you, or connected in your brain, or whatnot. What matters is the event. (Whether the event has meaning is a completely separate question!) Information theory is a nice place to start, but I warn you, it can get heavy sledding pretty quickly, because the technical definition of information (which matters if you are talking about black holes and things) is not the colloquial definition (i.e. semantic or conceptual information). --Mr.98 (talk) 16:07, 21 August 2012 (UTC)

Ok, I did check it out - double black diamonds! Thanks but wouldn't you have to preempt the "lack of thing to communicate" with a bunch of information communication to define what the lack of thing would actually communicate? So a connection is physical. Say the brain only uses 10% of its actual capacity, if it then was using 50% would that mean more connections...more mass than the 10% brain?165.212.189.187 (talk) 16:51, 21 August 2012 (UTC)

Bekenstein bound#Human brain gives a limit, though not one presumed to be of any practical relevance. Wnt (talk) 17:35, 21 August 2012 (UTC)

I think the existence of the Bekenstein bound implies that entropy has some kind of gravitational effect, but I don't know what the mechanism of that would be. It may be an open question. The thing about only using 10% of the brain isn't true—see ten percent of brain myth. -- BenRG (talk) 20:29, 21 August 2012 (UTC)

The type of information discussed in information theory (or when thinking about black holes) does not require consciousness to communicate. It just means "sequences of events other than pure entropy," or something like that — an opposite of randomness, a form of order. It has no inherent mass. --Mr.98 (talk) 22:55, 21 August 2012 (UTC)

Pure entropy and randomness are opposite of information??165.212.189.187 (talk) 20:12, 22 August 2012 (UTC)

What about this lizard

This photo was taken in Artemisa (Cuba) here these lizards are very ordinary, but I can’t find anyone that tell me it scientific name http://en.wikipedia.org/wiki/File:Brown_lizard.jpg — Preceding unsigned comment added by Iskander HFC (talk • contribs) 14:35, 21 August 2012 (UTC)

The Cuban brown curly-tailed lizard, Leiocephalus cubensis -- OBSIDIAN†SOUL 15:01, 21 August 2012 (UTC)

(Chinese) Vegetable Identification

Can anyone identify this vegetable? It's common in Chinese grocery stores. Here's another photo.

Thanks! 2601:8:500:1B:8DFC:C408:2A71:54C0 (talk) 15:45, 21 August 2012 (UTC)pebble

Looks like Bok Choy, known in the west as "cabbage". --Jayron32 15:52, 21 August 2012 (UTC)

(Doh never quite quick enough!!) It's usually called 'Pak Choi' in my local supermarket but seems to have a variety of names. The wikipedia Article Chinese cabbage is what comes up when you search pak choi in Wikipedia but the images don't seem to match with what I'd call Pak Choi..however if you do a google image search you'll find loads of pictures like yours. ny156uk (talk) 15:54, 21 August 2012 (UTC)

We call it Pechay, and I grew up believing it was an English word.-- OBSIDIAN†SOUL 16:09, 21 August 2012 (UTC)

See wikt:pak choi and wikt:白. Wnt (talk) 17:46, 21 August 2012 (UTC)

That's funny. Many years ago I stopped in Angeles City on the way to Mount Pinatubo and saw curly/twister fries for the first time in my life. For years I believed they were indigenous. Perhaps they were. I never checked. Sean.hoyland - talk 18:08, 21 August 2012 (UTC)

Hah. And I also thought Goldilocks Bakeshop was an American company (I mean jeez, the girl was blonde). :P -- OBSIDIAN†SOUL 18:16, 21 August 2012 (UTC)

Marvelous. Sean.hoyland - talk 18:21, 21 August 2012 (UTC)

Radius of the universe

Ian Stewart's Concepts of Modern Mathematics contains the paragraph:

A certain theoretical physicist secured himself a mighty reputation on the basis of his deductions, on very general mathematical grounds, of a formula for the radius of the universe. It was a very impressive formula, liberally spattered with es, cs, hs and a few πs and √s for good measure. Being a theoretician, he never bothered to work it out numerically. It was several years before anybody had enough curiosity to substitute the numbers in it and work out the answer. Ten Centimeters.

Can someone tell me the name of the physicist and the formula? Thanks---Shahab (talk) 16:41, 21 August 2012 (UTC)

It may very well be that this is merely a humorous anecdote (or, in common English, a "joke"), and is not intended to be a scrupulously correct historical assessment of an actual event. That is, it is meant to be illustrative of a common error in theoretical physics (that it exists in the abstract, without an attempt to provide actual experimentation or numbers), and not meant to be an actual historical example. In other words, it sounds like the kind of thing that a theoretical physicist would do (propose a formula and then not bother to check it). The actual size of the Universe (as a scientific fact) is discussed in the Wikipedia article and section Universe#Size.2C_age.2C_contents.2C_structure.2C_and_laws and is more fully fleshed out in articles linked from there. Historically, the physicist most commonly associated with our current understanding of the Universe and its actual size (or lack thereof) is Edwin Hubble, though I seriously doubt that he is the source of the above anecdote. Or indeed, that anyone may be. --Jayron32 16:52, 21 August 2012 (UTC)

I've never heard this story before and it doesn't sound real. It sounds like a Hollywood hack writer's idea of theoretical physics. I tried googling and found only the book itself and a similar thread on physicsforums.com which reached no conclusion.

There are cases of famous physicists making mistakes which went undetected for long periods of time, such as John von Neumann's hidden-variable proof of 1932 which was called into question 34 years later by J.S. Bell. I see the article mentions a 2010 paper claiming that von Neumann was right after all, but if he's right it means Bell's error wasn't discovered for 44 years, so this is still a good example. :-) -- BenRG (talk) 18:46, 21 August 2012 (UTC)

Multiple Big Bangs

Could more than one Big Bang have happened at the same time as ours? I realize that our concept of space doesn't apply to before then, but could a non-interacting bang have happened in the same "locaction", such that we can't detect it or that we can only see effects like dark matter or energy, but in themselves could house a perfectly viable universe, one where ours is the mysterious missing matter? Mingmingla (talk) 17:12, 21 August 2012 (UTC)

No, I think this doesn't make sense. Dark matter and dark energy occupy the same spacetime as us, and one spacetime continuum means one big bang by any reasonable definition. There is a notion of particles that interact with each other but not at all (except gravitationally) with the particles we're made of, making them undetectable by anything other than dark-matter-like effects. This is sometimes called shadow matter, although that article seems to be about something slightly different. -- BenRG (talk) 18:54, 21 August 2012 (UTC)

Yeah, what's the difference between there being multiple big bangs at the same place and time, and there being one big bang that included particles that don't interact with ours? 203.27.72.5 (talk) 21:55, 21 August 2012 (UTC)

In any case simultaneity is relative. Plasmic Physics (talk) 23:18, 21 August 2012 (UTC)

Simultaneity is not relative when the position is the same. Someguy1221 (talk) 23:44, 21 August 2012 (UTC)

It is the velocities are different. If you imagine a neutron moving towards you at 0.5c and a neutrino moving away from you at 0.5c on a direct collision path, and you see both the neutron undergo beta deacay and the particles collide at the same time, a different observer who was perpendicular to the flight paths of the two particles would have observed them in a different order. 203.27.72.5 (talk) 00:29, 22 August 2012 (UTC)

No, they really don't. If two events occupy the same position in spacetime, they can only ever be seen as simultaneous. It's a trivial reduction of the basic example given in Relativity of simultaneity in which the length of the train is 0. Someguy1221 (talk) 00:41, 22 August 2012 (UTC)

But the Big Bang does not occur in spacetime, spacetime is a result of the Big Bang - the Big Bang is not located at any position. Plasmic Physics (talk) 01:38, 22 August 2012 (UTC)

Well, yes :) I was just addressing the general point about simultaneity. Someguy1221 (talk) 01:46, 22 August 2012 (UTC)

Wait a minute, did I just void my own statment - "at the same time" does not make sense without the crucial factor of time? Plasmic Physics (talk) 06:35, 22 August 2012 (UTC)

Castleton Botanical Gardens

This garden or gardens are mentioned in several Wikipedia articles, including Jamaica and George Samuel Jenman, and Google gives several results, but the problem is that there are variations on the name, sometimes two in the same article. So, which of the following six variations is the actual name of the garden?

• Castleton Garden
• Castleton Gardens
• Castleton Botanic Garden
• Castleton Botanic Gardens
• Castleton Botanical Garden
• Castleton Botanical Gardens

Once I have the formal name, I can make it consistent within English Wikipedia.

The nearest that I could find to an official webpage is The Jamaican Ministry of Agriculture and Fisheries Public Parks Department, which uses "Castleton Botanical Garden" in its header, although just to confuse matters it calls it "Castelton Gardens" in the following text. Alansplodge (talk) 19:36, 21 August 2012 (UTC)

Question about oral sex

please seek competent medical advice
The following discussion has been closed. Please do not modify it.
Does the eating of semen affect your health in any way? Please answer as soon as possible, I've read that it causes cancer and I've been doing it for a while and it's ruined it all for me, I'm afraid of it now. — Preceding unsigned comment added by Alabamaboy1992 (talk • contribs) 20:06, 21 August 2012 (UTC) Sorry, but we can't offer medical advice on the Reference Desk. StuRat (talk) 20:25, 21 August 2012 (UTC) No, we can't. μηδείς (talk) 20:35, 21 August 2012 (UTC) He ain't asking for advice. He asks if there are effects in general, not what he has to do now. I know this is a pretty weird question to see, but try to read it first--R8R Gtrs (talk) 20:39, 21 August 2012 (UTC) The question uses the phrase "affect your health" - thus it is a medical question. Case closed. Roger (talk) 20:45, 21 August 2012 (UTC) And...? I could also ask "How does drinking arsenic affect your health? I've heard people used to do it for cosmetic reasons." It's a general sort of "your" and we can point to the arsenic article and give info about the past uses. Dismas|(talk) 20:49, 21 August 2012 (UTC) I don't get it. I saw recently a question where a man was asking how having a cold gets feel weak. And no single person found it inappropriate. I'm also pretty sure that the arsenic question, if asked, should be replied. I'd prefer an answer like arsenic destroys the stomach cells by disintegrating an important lipid (for example, I dont really know how arsenic poisoning works), which results in severe pains, internal bleedings, and death (made up consequences). So do I get it right? You can't ask "how does walking if shorts and a shirt in winter affect one's health", but rather when the effect is known, "how so I feel weak having a cold"? Do you feel the difference between medical questions and medical advice? Advice means you suggest something to do... The individual doesn't want that. It's that they are asking about their own case that makes it medical advice, as in "I've been doing it for a while and it's ruined it all for me, I'm afraid of it now". StuRat (talk) 21:20, 21 August 2012 (UTC) Huh. That's a good point. However, I am still sure that texting a list of possible consequences without giving emotions would not qualify as advice, and that things outside the question don't matter-- essentially, that's still the same question. Maybe I misunderstand the word advice? However, you may be right in that the man could be better sent to the doctor... Tl;dr Still don't agree somehow/Won't argue further (doing the "wrong" things to achieve the ultimate right one is acceptable to me, if that's the case) What you probably read in the news a couple years ago was that HPV, which can be transferred through oral sex, is an increasing cause of oral cancer [23](more than smoking, perhaps). There is no advice on course of action intended to be conveyed by this statement, consult a medical professional, blah blah blah, etc. Buddy431 (talk) 21:40, 21 August 2012 (UTC)

This is a very general question, and we would be remiss if we did not direct readers to Oral sex#Health risks and other studies for some useful public health information. Wnt (talk) 12:34, 22 August 2012 (UTC)

August 22

A New Life Beginning at Fertilization

Is the statement that a new life begins at fertilization (also known as conception) a "soft" scientific fact, rather than a "hard" scientific fact? The reason that I'm asking this question is because I have an intelligent (overall, not necessarily on this topic) friend who said that life beginning at fertilization is a soft scientific fact, since the definition of life is based on scientists' opinions rather than on any universal truth. This is in contrast to, say, the Earth orbiting the Sun, which is a hard scientific fact since there is absolutely no disputes about it and it is based on universal truths rather than on opinions. My question is--is my friend right or not, and if not, why not? Futurist110 (talk) 02:51, 22 August 2012 (UTC)

Life began at some unknown event a little less than 4 billion years ago or so. Everything else is continuation of that event. --Jayron32 02:57, 22 August 2012 (UTC)

I meant a new life. Sorry for the confusion. Futurist110 (talk) 03:02, 22 August 2012 (UTC)

Now you have to define "new". Someguy1221 (talk) 03:05, 22 August 2012 (UTC)

And you have to define "a". The problem is, there are lots of events, and lots of slow processes which lack a single event, along the path of life, where by an individual "organism" is said to be progressing towards its own independence. If it were that simple, we wouldn't have the controversy. The point is, the only reasonable event where one could say there was a definite start was the original moment of abiogenesis. After that, there are not any convenient single moments in time, nailed to the exact second, which differentiates you as an individual from that initial event. Conceptually, "birth" and "conception" mark the two most convient, for the simple minded, but only because they seem to be nice, simple events. But as moments, they aren't necessarily all that advantageous for defining a "start" since anything which would grant them that primacy seems trivial once you get into the processes. Why is birth special? A newborn infant would die if left unattended after birth, and a child delivered before natural birth (either by caesarean or induced labor) can be cared for and raised to an adult. So why birth? And why conception? There are similar problems with making that moment special. Any reasoned argument that attempts to nail down that "moment" can be presented with similarly reasoned and reasonable arguments to the contrary. The real answer is that the only answer is political: there is no agreed "scientific" definition which will satisfy the need to define when a human being becomes an individual being, and when it isn't. So, you're going to need to find your guidance elsewhere. --Jayron32 03:38, 22 August 2012 (UTC)

Note in particularly saying a new life begins at conception is problematic because monozygotic siblings come after conception, so your 'a new life' can become two or more new lifes. Ultimately as Jayron32 and BenRG said, this isn't a scientific question. Nil Einne (talk) 04:06, 22 August 2012 (UTC)

Conception is a good mark in the sense of defining as to when a new human development process begins, since human development generally goes from conception (or when a zygote is split into twins, etc.) to death. Futurist110 (talk) 04:23, 22 August 2012 (UTC)

But there is no conception without ejaculation. So why is conception more important than ejaculation. And there is no ejaculation without that person having being conceived, and then you get a recursive set of events back to the moment of creation. Conception is not an event without its own causes and precedents, so there isn't anything particularly "first" about it. --Jayron32 04:38, 22 August 2012 (UTC)

WP:EC (Assuming I understand the spirit of your question...) Whether or not a definition of life is a matter of opinion is, in itself, somewhat of a matter of opinion. See Life#Definitions, which says "It is a challenge for scientists and philosophers to define life in unequivocal terms.", and gives three references. A counter argument to "life begins at conception" could revolve around whether or not a zygote meets all the criteria for life. You do not specify human life per se, but often these sorts of questions come up in the context of human reproduction. A related, but much more difficult question is then, if a zygote is alive, is it a human? Harder yet: is it a person? By nature, these questions are not purely scientific in nature, and must perforce be answered in the context of some philosophical, political, and/or legal framework. Needless to say, the answers to these questions are the subject of much discussion and dispute. SemanticMantis (talk) 03:06, 22 August 2012 (UTC)

(ec) I don't believe many scientists argue that an embryo isn't alive. However, for setting abortion policy and such, other questions come up, like at what point the embryo becomes viable, outside the womb. There you will get a range of answers. StuRat (talk) 03:08, 22 August 2012 (UTC)

I am aware of the difference between life and personhood. The fetus becomes viable at about 21.5 weeks or so right now (with current technology), which is a hard fact. Futurist110 (talk) 04:23, 22 August 2012 (UTC)

Sperm are alive too. Conception means the death of a sperm. HiLo48 (talk) 03:19, 22 August 2012 (UTC)

Sperm are a part of your body. They have your DNA and are not a whole entity passing through any stage of human development, unlike a zygote. Futurist110 (talk) 04:23, 22 August 2012 (UTC)

Interesting perspective. The question didn't explicitly ask about human life. HiLo48 (talk) 07:45, 22 August 2012 (UTC)

Futurist110, apparently you slipped when you said that "the Sun orbiting the Earth" ... "is a hard scientific fact". [I need to use your username for clarity, because the previous comment is not indented.]

—Wavelength (talk) 03:25, 22 August 2012 (UTC)

(now indented)

If object A is orbiting object B, it also means that object B is orbiting object A. Ergo the Sun is indeed orbiting the Earth. A8875 (talk) 03:57, 22 August 2012 (UTC)

Also not true. The Earth does not orbit the Sun, nor does the Sun orbit the Earth. The two orbit a common barycenter. Insofar as barycenter of the earth-sun system is located within the sun itself, it is more correct to say the Earth orbits the Sun than the other way around, but the scrupulously correct answer is that they orbit their common barycenter. --Jayron32 04:15, 22 August 2012 (UTC)

Sorry. That was obviously a typo on my part. I obviously meant "the Earth (and the other seven planets) orbiting the Sun". Futurist110 (talk) 04:23, 22 August 2012 (UTC)

Even if the barycenter is outside both object A and object B people still use the word "orbit". In vernacular speech "orbit" pretty much applies to all circular and elliptical movements, regardless of where barycenter is. This usage is not scientifically correct as you pointed out, but it's what people uses. A8875 (talk) 04:29, 22 August 2012 (UTC)

Your real question is when a new human life begins. That isn't a scientific question at all, "hard" or "soft". It's a question of definition or, at best, of ethics. The only scientific answer is Jayron's. -- BenRG (talk) 03:42, 22 August 2012 (UTC)

Is there an impartial, objective (non-biased) definition to life, though? My friend says that even if all scientists agree on one definition, that this definition of life isn't objective and that there is no objective definition to life. Futurist110 (talk) 04:23, 22 August 2012 (UTC)

Like others mentioned above, the definition of when a life begins is mostly a philosophical and a political one. Since definitions are tautologies (by definition), they are not subject to the scientific process. Definitions cannot be "wrong", but they can be counter-productive. For example if the Sanctity of Life Act passes, it would mean that 27% to 37%[24] of new-born US residents die in the womb, bring the average life expectancy down to the low 50s, behind Kenya, Congo, and Niger. A8875 (talk) 04:17, 22 August 2012 (UTC)

Yes, but by the new standards of this law, all other countries' life expectancies would significantly decrease as well, while life expectancy since birth (the traditional measure) would still stay the same in the U.S. and everywhere else. Futurist110 (talk) 04:25, 22 August 2012 (UTC)

Precisely. It would necessitate the concurrent usage of two definitions, and two separate life expectancy rates in pretty much all birth related international documents and discussions. Hence "counter-productive". Thank God WP's country infobox doesn't have life expectancy on there.A8875 (talk) 04:34, 22 August 2012 (UTC)

It probably won't be that counterproductive considering that one would be able to calculate the new life expectancy very quickly. Futurist110 (talk) 04:38, 22 August 2012 (UTC)

It will still be a hassle though. Since each country publishes their own statistic based on their indigenous definitions, every time an American hears a birth or life expectancy related statistic from another country, they have to perform the mental calculations. This is by no means a new problem. Cuba has higher infant mortality rate than US[25] because the definition of "infant mortality" differs between the two countries. Many people interpret this statistic erroneously by concluding that Cuba's universal healthcare is responsible (admittedly it's a minor contributor). A8875 (talk) 05:36, 22 August 2012 (UTC)

• Speaking of "a" life is problematic at any time, even for adults. Consider split-brain experiments. Life is not really designed to be counted in this manner, as is particularly evident in some phyla such as siphonophores. In humans, every cell is potentially clonable, and thus potentially a life.

• Sperm and eggs are each arguably a haploid generation (gametophyte) and their union marks a diploid generation.

• The end of human life in the legalistic sense, as opposed to viable cells for culture, is defined in terms of brain death. The brain death criteria might also be applied to fetuses to define the beginning of life.

• As I recall, neurotransmitters start up around 6-7 weeks, forerunner neurons around 10, and others around 12 weeks. These time intervals are not dissimilar from comments about quickening by Aristotle and Saint Augustine (I think it was) at 40 to 80 days after conception, which presumably are based on a subjective sense of when an aborted fetus appears alive. (After all, they had abortions back then) However, authorities have long maintained that the "higher" ability to sense pain awaits the 8th month of gestation or so. (I'm not going to look up cites for all this stuff because it's not the question asked).

Bottom line: not a hard scientific fact. You might as well ask how many pieces of yellow there are in a lemon. Wnt (talk) 04:51, 22 August 2012 (UTC)

As others have said, the concept of "life" as it is being used here, is an ethical question more than it is a scientific one. At best science can inform some of those moral opinions. Conception gets thrown around as some sort of brightline quite a bit, but whether or not the science backs that up is questionable. An enormous number of fertilized eggs are lost without the woman ever knowing it. Historically there have been a wide variety of determinations about when "life" begins, including conception, quickening, birth, and even after that. In a very strict legal sense, personhood has been understood as birth in the U.S. for example. There are laws that make the death of a fetus criminal, whether it's abortion or something else, but that doesn't mean the fetus is considered a person. From a strict legal standpoint, birth is a clear brightline. Shadowjams (talk) 05:08, 22 August 2012 (UTC)

Just because a lot of fertilized eggs are lost naturally doesn't mean that they weren't alive. Those historical definitions were generally based on the knowledge back then, not on the knowledge now. For instance, in the pre-industrial era many people thought that life only began once the fetus began to move (quickening, as you say), whereas we now know that this is not the case. The legal sense isn't very practical when it comes to these matters, as the law can and often does change and since the law is currently inconsistent (if the woman wants the offspring, then the offspring is a person, if not, than the offspring is not a person). Futurist110 (talk) 05:14, 22 August 2012 (UTC)

My point in mentioning the number of lost fertilized eggs is simply to suggest that conception isn't a defacto brightline moment; you could choose others including implantation, quickening, third-trimester, sentience, birth, etc. Shadowjams (talk) 05:41, 22 August 2012 (UTC)

The question we're all skirting around here is "So what?" The usual goal of defining when life starts is to justify one's policy position in the abortion debate, as though the first should lead unambiguously to the last, but that isn't necessarily so. In no other policy decision is the "scientific definition of life and its start" used to provide a rationale for the taking of (or for the preservation of) life, whatever your working definition is. If we really want to get down to it, human societies since time immemorial have never really had any universal principles which preserved all human life in all cases. Every society has defined situations when the taking of a human life (either through self defense, war, capital punishment, or whatnot) is allowable. So even conceding that it may be possible to define the "start of life" (not admitting that one can, merely conceding to make the next point), it doesn't mean squat when trying to decide where one stands on the abortion debate. There is no universal principle, it is merely a weighing of competing interests, and reasonable people will value those interests differently. People who place values on one side of the scale end up as "pro-life" and others, with different values, end up as "pro-choice", but it doesn't mean that either position is based more than the other on "sound science". Neither is, fundementally. That's why the debate is intractable: it ultimately comes down to individual conscience, and in matters of conscience, it is possible for reasonable people to arrive at different conclusions. --Jayron32 05:23, 22 August 2012 (UTC)

For the record, I wasn't trying to say or imply that one acknowledging life beginning at conception as equivalent to saying that abortion is wrong and/or morally unjustifiable. The abortion debate has a lot of other factors at play other than when life begins. I was simply wanting to know the validity and accuracy of my friend's statement. Futurist110 (talk) 05:38, 22 August 2012 (UTC)

As Shadowjams says succinctly above, there isn't a magic moment, however. Conception is as good as any other moment, which is to say that it isn't better than them either. You're friend's statement isn't even wrong, as the saying goes. --Jayron32 05:46, 22 August 2012 (UTC)

As I said above, we do use brain death to make decisions, i.e. we evaluate the "scientific definition of life and its end" based on the belief that neural signalling is required for "life", even though obviously many other organs of the body remain alive after brain death. The zygote is one more type of cell that is not a neuron. Wnt (talk) 12:30, 22 August 2012 (UTC)

True, but we also use other events to decide when a person is worthy of death; i.e. when they are a soldier in the army of another country, or when they have committed certain crimes, or have certain diseases, or any of a number of other criteria, that have little to do with definitions of "life" and its milestones. No society has ever, as a culture, taken the step that all human life in all forms is to be preserved at all costs, and no society that has decided that some lifes aren't worth protecting (or that some lifes are worth ending) has ever based those decisions on such purely on such milestones. Thus, even conceding that there are some milestones in a life which are worth taking special note of, it doesn't directly follow that policy needs be based solely (or even primarily) on those milestones. It comes down to subjective value on individual lives, and on qualities relating to those lives, and reasonable people will disagree about subjective value. --Jayron32 12:41, 22 August 2012 (UTC)

Well, it sounds like you're saying that by allowing those who have suffered brain death to die completely, that we are making a decision to perform euthanasia. I suppose that is a position you can take, but I think that most people making that decision do so out of the genuine belief that those in that situation are not meaningfully alive, rather than out of a belief that their lives aren't worth protecting. Wnt (talk) 12:56, 22 August 2012 (UTC)

Well, that's because you define "meaningfully alive" to exclude a certain group of people. If we have differing definitions of what it means to be "meaningfully alive", then we have differing definitions over what value to place on what bits of living tissue. That's the crux of the problem. Human society has for millenia redifined humanity to make killing and other inhumane acts ethically tolerable. Without making any judgement (for the sake of this discussion) which definitions of "really human" and "meaningfully alive" and any of a number of other concepts, people generally agree that "really alive, really human people" are accorded certain rights, but if we don't all have the same definition of what those terms mean, then we have conflict. Again, I'm not saying whether or not your criteria for "brain death" is the correct one to choose when making decisions about what it means to be alive, rather I am saying that no particular choice is entirely incontrovertable: there is no single choice where every single person will reasonably agree with you. That doesn't mean you aren't right, it just means that you aren't going to be free from conflict or controversy, and that any particular choice about your criteria is going to be so self-evident as to be agreeable to all people. --Jayron32 14:29, 22 August 2012 (UTC)

Not to beat a dead horse here (oh wow that's a bad pun...) but Jayron's point is particularly acute given your example of brain death. It's only relatively recently (past few decades) that brain death rather than cardiac death has been the relevant standard in terms of law and medicine. The most obvious consequence being the wider (although still too small) availability of organ transplants. Shadowjams (talk) 17:07, 22 August 2012 (UTC)

Reference Needed for Multiplicity (psychology)

Does any psychologist recognize this and have good source for it? It is risking to be deleted. Thanks.Wikipedia:Articles_for_deletion/Multiplicity_(psychology)#Multiplicity_.28psychology.29 -- RexRowan  Talk  18:11, 22 August 2012 (UTC)

WP:CANVASS might be relevant to posting about an ongoing AFD. Edison (talk) 19:07, 22 August 2012 (UTC)

Thank you for pointing it out for me. I have looked for reference on the psychology project. -- RexRowan  Talk  19:12, 22 August 2012 (UTC)

srface charge density on a sphere

Let's say you know the potential at every point on the surface of a sphere. How then do you find the surface charge density? --150.203.114.14 (talk) 15:17, 22 August 2012 (UTC)

Does the article charge density help you figure that out? It looks like it involves some simple calculus to solve. --Jayron32 15:21, 22 August 2012 (UTC)

I see no equation relating charge density to potential. --150.203.114.14 (talk) 15:29, 22 August 2012 (UTC)

That equation would be Gauss's law... which can be stated as an integral, or formulated into an inversion-problem so that you can determine the charge distribution, given the potential. In nontrivial cases, the inverse problem may be underconstrained. In realistic physical situations, complicated potentials are unlikely, as a conducting sphere will relax to an equipotential surface after some period of time. So: to directly answer your question: given, potential as a field, to solve for charge distribution we invert Gauss's law, making suitable approximations that match our physical expectations. Depending on those assumptions, and the condition of the potential field, the mathematical methods could simply be direct solution of a simple algebraic formula, or may require very detailed machinations. Nimur (talk) 16:01, 22 August 2012 (UTC)

Double tolerance problem article ?

Do we have one ? Perhaps under another name ? (I suppose this is a special case of tolerance stack up.)

The problem, in short, is that two mating parts (lets say a jar and a lid) normally fit fine, but when the jar is at the wide end of it's tolerance and the lid at the narrow end of the tolerance, they don't fit. This could either be a result of the design tolerances being too generous, or the items exceeding those tolerances. (I suspect that manufacturers will accept a certain degree of this problem, as avoiding it by tightening up on tolerances can be more expensive than the occasional pair that don't fit together.)

The result is that most lids fit most jars, but occasionally a certain combo won't work. Tellingly, if either a different jar or lid is swapped in, then they usually fit again.

If we don't have an article, I'd like to create one, so would like any other names for this and examples you can think of.

There's some mention of it here. 203.27.72.5 (talk) 20:57, 22 August 2012 (UTC)

can't break speed of sound?

I've heard that in the 1920s, 30s, or 40s, scientists thought that an airplane could not break the speed of sound. I googled and couldn't find anything. Did scientists really think that? Did some think that? Is it an urban legend? Bubba73 ^{You talkin' to me?} 21:33, 22 August 2012 (UTC)

Early planes that approached the sound barrier when diving often crashed due to the (by their standards) extreme forces. At the time, these problems were believed to be insurmountable. See note 2. 203.27.72.5 (talk) 21:49, 22 August 2012 (UTC)

Supersonic airplanes do need quite a few differences in design, to fly properly, like swept back wings, a long, narrow fuselage, etc. So, when trying to fly a plane not designed for such speeds over the speed of sound, it may indeed crash. StuRat (talk) 22:01, 22 August 2012 (UTC)

A major breakthrough was the discovery that in the transonic phase an effect called Mach tuck occurs, in which shock waves build up on the lifting surfaces causing the nose to plunge downwards. This was discovered by the team working on the Miles M.52 project during WWII. They devised the "all-moving tail" or Stabilator to overcome this, which is now universal on all supersonic aircraft. Sadly, before the project was cancelled, the Bell Aircraft company was given access to the drawings and research on the M.52, but the U.S. reneged on the agreement and no data was forthcoming in return." The Bell X-1 took all the credit, complete with British designed tail. Alansplodge (talk) 22:16, 22 August 2012 (UTC)

Using fuel to cool an internal combustion engine

Jet engines commonly use the fuel to cool the area around the engine. Could the same approach work on an internal combustion engine, in conjunction with air cooling, or is the amount of fuel burned just insufficient for this ? (In the case of a gasoline engine, the gasoline could boil in the engine block, to cool it, and the fumes would then be burnt inside the cylinders.) StuRat (talk) 22:36, 22 August 2012 (UTC)

The specific heat - based thermal capacity, and the latent heat of vaporistion, does have a cooling effect on any IC engine (you obviously mean a piston engine here - an aircraft "jet" engine is also an internal combustion engine), but the effect is not that strong, and how/where it does it, depending on the type of engine, is not so obvious perhaps to a lay person as it may be for a turbine ("jet"). In a turbine, the design specifically involves having relatively cool areas (including cooled by fuel) and relatively hot areas (the downstreem combustion area) for properties of materials reasons. In piston engines, cooling happen, but the design aims are different.

In a diesel egine, fuel is injected into the combustion chamber at ignition time, in liquid form at a temperature below the air temperature at that time. Therefore, the fuel provides a cooling effect from its thermal capacity, and by absorbing latent heat of vaporisation as it is vaporised in order for combustion to occur.

In a diesel engine, the cooling effect of the fuel is undesirable, as it lowers combustion temperature and thus lowers gas expansion and thermodynamic efficiency.

In a gasoline engine, the fuel still has a cooling effect, but how it does it is a little less obvious. In a carburettor engine, evaporation in the carburettor casues the intake charge to be cooled, so combustion has a lower temperature to start from.

It should be realised that in a typical aircraft "jet" engine, thermodynamic efficiency is not that high, and gas velocities are high. These two reasons mean that cooling of combustion chamber walls is important. In practical pistion engines, efficiency is high and gas velocities low, so cooling of combustion chamber walls is not critical - typically only about 6% of combustion heat is lost via the combustion chamber surfaces. Ratbone124.178.39.239 (talk)