Wikipedia:Reference desk/Archives/Science/2010 March 27

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March 27

Do topical vitamins still work if dietary intake is sufficient?

I know that a number of studies show topical vitamin A fights acne, and C and E rehydrate dry skin. Has it been studied whether these effects vary with dietary intake or bloodstream levels of these vitamins? That is, how do we know the topical vitamins aren't simply replacing missing dietary vitamins? NeonMerlin 00:39, 27 March 2010 (UTC)

Just a guess - but most people get more than enough of those three vitamins in their diet - yet they still get dry skin and acne. If topical use of those vitamins actually has a measurable effect then they can't simply be making up for inadequate diet. SteveBaker (talk) 05:56, 27 March 2010 (UTC)

It is worth asking at the outset whether Vit A actually 'fights' acne and whether Vit C and E rehydrate the skin. My understanding is that acne is an infectious condition of the follicles of the skin and rehydration can only occur in the presence of added water. So, is vitamin A some form of antibiotic and how does vitamin C and E emulate water? I would check the source of the studies, the sale of cosmetics is riddled with dubious and outrageous science. Richard Avery (talk) 09:01, 27 March 2010 (UTC)

The hydration of skin occurs from the inside out as much as from the outside in, skin becomes dry because evaporation is occuring faster than replenishment from internally. Most "moisturizers" work not by rehydrating the skin, but by reducing evaporation from the skin. They are usually some sort of hydrophobic oil of some sort which prevents drying out. If the skin retains moisture, it doesn't dry out as fast. I have no idea if this is so, but Vitimins E & C may work by a similar mechanism. --Jayron32 21:11, 27 March 2010 (UTC)

Interference (wave propagation)

Animation of interference of waves coming from two point sources. There is strong nett radiation in directions where the source radiations add constructively and no radiation in the directions where they cancel. Cuddlyable3 (talk) 16:26, 27 March 2010 (UTC)

In that article, the description of the image to the right says: "As time progresses, the wave fronts would move outwards from the two centers, but the dark regions (destructive interference) stay fixed."

Is that true? 1) If the dark regions stay fixed, then how could the light regions move? 2) The animation further down the page does not have any stationary dark regions. Thanks 78.149.198.14 (talk) 01:19, 27 March 2010 (UTC)

The "dark regions" in the picture would be the cyan parts. There's several unmoving cyan lines radiating outward. There are also cyan regions moving along with the other-colored regions, but that's not what it's referring to. 67.172.112.226 (talk) 01:43, 27 March 2010 (UTC)

That incoherent caption is interfering with the propagation of my thoughts. When a wave from one source meets a wave (having the same frequency) from the other source, they destructive interfere at certain points. Those particular waves then move outward, but following waves will destructively interfere at exactly the same spots, so those locations will always be dark. Clarityfiend (talk) 04:27, 27 March 2010 (UTC)

I cannot see anywhere in the animation, for example, that stays the same colour. So nowhere stays dark. 89.243.43.75 (talk) 15:20, 27 March 2010 (UTC)

"There's several unmoving cyan lines radiating outward." How can they radiate outwards and be unmoving at the same time? A contradiction. 89.243.43.75 (talk) 15:16, 27 March 2010 (UTC)

Radiating in the sense of being a line from the centre to the edge (like a radius of a circle), not radiating in the sense of radiation. The lines are static. There are 6 in the top half and 6 in the bottom half of the image. --Tango (talk) 16:48, 27 March 2010 (UTC)

Thanks for the clarification. So if for example you had two nearby radio transmitters, and were driving around with a car radio, then if you drove along one of the lines described above, you would not hear anything? Would this also apply if the radio transmitters were transmitting signals at a different frequency AND/OR a different phase? Thanks 78.144.250.185 (talk) 15:59, 28 March 2010 (UTC)

When two transmitters radiate identical signals then yes, cancellation causes nulls in some directions where a car radio would receive little or nothing. The directions of the nulls change if one source is phase shifted relative to the other. That is a simple example of a Phased array. If the sources are at different frequencies then the radiation pattern is not stable; if the frequencies are close the result is the same as a constantly changing phase shift. That is useful if one wants a transmitter beam to sweep across a given angle e.g. for a radar. Cuddlyable3 (talk) 22:45, 28 March 2010 (UTC)

Technically, you'd always hear something, as one of the transmitters would be further away, and wouldn't quite counter out the other. Incidentally, since sound is waves, you could just use two speakers so you don't need the radio. — DanielLC 06:35, 29 March 2010 (UTC)

Obviously we are speaking technically. It is only necessary for the cancellation to reduce the signal strength below the noise threshold of the receiver. Practical factors such as the transmitters not radiating identical powers will change the depth of the nulls. The reason cancellation can occur is because the distances from transmitters to receiver are unequal. Sound wave cancellation can also occur but it is difficult to demonstrate in the presence of indoor acoustics, the separation of human ears, and the difficulty of producing omnidirectional point sound sources. It is also unpleasant to listen to the prolonged sinewave tone that would be necessary. Cuddlyable3 (talk) 15:26, 29 March 2010 (UTC)

gravity

Although of higher local intensity or density throughout the universe is gravity the equivalent or substitute for atheists what God is represents for theists? 71.100.6.104 (talk) 03:09, 27 March 2010 (UTC)

No. Clarityfiend (talk) 03:25, 27 March 2010 (UTC)

Gravity is the weakest of the fundamental forces! If I ever feel the need to worship one of the forces holding the universe together, I'm going to worship the strong force, and death to all the infidels that worship the Weak nuclear force.

Seriously, though, I'm not a hundred percent sure what you're asking, but I'm pretty sure that the answer is "no." APL (talk) 03:26, 27 March 2010 (UTC)

May be you should try explaining to us why you would even think that. Dauto (talk) 03:32, 27 March 2010 (UTC)

When you talk about God creating the Universe to people who believe that the universe was created by the laws of physics then you get the impression that they have a substitute for God. Since one theory about the end of the universe is that the universe will end when the last Black Hole explodes and gravity is deemed responsible for holding a Black Hole together then it seems like gravity in that context must or might be their "god."

It may be a minor or perhaps frivolous question to some but I'm trying to phantom what it is that such persons find to be a plausible explanation for the basis or creation of the universe other than God. 71.100.3.207 (talk) 03:51, 27 March 2010 (UTC)

I would choose electricity rather than gravity, for obvious reasons. I hope no one is shocked by this. Edison (talk) 03:52, 27 March 2010 (UTC)

Atheist usually don't see god as a plausible explanation for the basis or creation of the universe at all. I don't see why you chose gravity out of all things as a possible substitute for god. Dauto (talk) 03:55, 27 March 2010 (UTC)

(after edit conflict)

Oh. I think most atheists are OK with not knowing exactly how the universe came to be. I can't speak for anyone but myself, but I feel smarter acknowledging that I don't know than I would feel if I believed a creation myth. APL (talk) 03:56, 27 March 2010 (UTC)

Incidentally, I don't just feel this way about the GREAT MYSTERIES OF LIFE, I feel this way in general. If someone asks me for directions to the post office, I would prefer to tell them that I don't know where the post office is, rather than give them some made up directions that are probably wrong. APL (talk) 03:58, 27 March 2010 (UTC)

Buddhism, a religion that does not teach the existence of any gods with the exception of a few sects (when do religions ever agree on anything?), teaches that there was no creation of this universe or of any living things. Everything is impermanent and mutates from one form to another. 67.243.7.245 (talk) 04:10, 27 March 2010 (UTC)

What can mutate from the remnants (if any) of the explosion of the last Black Hole? 71.100.3.207 (talk) 04:18, 27 March 2010 (UTC)

Whatever happens, happens. Everything in this world is in a way illusory. (says Buddhism) 67.243.7.245 (talk) 23:23, 27 March 2010 (UTC)

Not to preach here but to reconcile any problems I have in terms of fantastical belief I see God as the entity that fits a certain logical definition of omni-everything. Sort of like playing a game of mime and people try to guess what it is you are miming. When no one can guess, finally they give up and you give a name to whatever it was. 71.100.3.207 (talk) 04:23, 27 March 2010 (UTC)

The problem with your idea is that God represents a great many things to theists. Atheists might believe some alternative cause for the creation of the universe (big bang theory, for example) - but they don't use that as a 'replacement' for all of the other things that theists use their "god hypothesis" for. Atheists don't worship anything - so right there, neither gravity nor anything else is equivalent to gods for theists. Also, most atheists would be immediately happy to replace the big-bang theory with some other competing idea if it proved to be a better fit for the observable facts. It takes a lot more than mere facts to persuade theists to change their views...which is likely the only reason they are theists in the first place. SteveBaker (talk) 05:54, 27 March 2010 (UTC)

Sounds like you're saying atheists are non-theists that worship facts. 71.100.3.207 (talk) 08:42, 27 March 2010 (UTC)

Did you miss the sentence "atheists don't worship anything"? Claiming the contrary is a popular sport (at least among theists), but I've never understood why. Algebraist 10:54, 27 March 2010 (UTC)

Another problem is--if God is real, that is, part of reality, then how did reality come to exist? This topic tends to lead to an infinite regress--and while i enjoy infinity as much as the next guy, I can't see how it supposts the notionon of God. Pfly (talk) 10:15, 27 March 2010 (UTC)

I think the closest you're going to get is that many but not all atheists have a reverence for the idea of the universe as a whole—with all its long history, its complexity, its improbability, and its incomprehensible vastness—that might come at least somewhat close to the reverence that many religious believers have for the idea of God. I would say (as an atheist of sorts, and one who has spent a long time associating with a wide spectrum of self-described atheists) that such is not a totally ridiculous statement. But atheists don't think the universe will help them (usually much to the contrary—the universe cares not for your problems!), or is a cosmic "self" that has any true intelligence, or that the universe dictates any kind of straightforward moral code.

Moreover, atheists are not organized. Some think Richard Dawkins is keen, some think he is an idiot. There is nothing more cantankerous and argumentative than a meeting of atheists. They agree on almost nothing (other than their lack of belief in the validity of religion), much less the proper basis for being an atheist. Trying to find a "substitute religion" is kind of a fruitless endeavor. I think you will do better in understanding "the other side" by just trying to make sense of it on its own terms—its beliefs, its values, its totems—than just trying to Find/Replace religious concepts with atheistic ones.

Anyway, no, "gravity" does not mean God to an atheist, it is not even close. Gravity is no more awe-inspiring than magnetism. (I think the latter is more spooky on a day-to-day level, to be honest!) It's neat that we can extrapolate from forces we experience here on Earth and make sense of the movement of planets, stars, galaxies, the entire universe as a whole! But an atheist is going to see that as a testament to human ingenuity, nothing more. Perhaps that is the more profound point: if you want to see what an atheist substitutes for "God", look in a mirror! ;-) --Mr.98 (talk) 12:41, 27 March 2010 (UTC)

Note: the question appears to be related to a quote attributed to Carl Sagan: "The idea that God is an oversized white male with a flowing beard who sits in the sky and tallies the fall of every sparrow is ludicrous. But if by God one means the set of physical laws that govern the universe, then clearly there is such a God. This God is emotionally unsatisfying... it does not make much sense to pray to the law of gravity." It's not listed on his Wikiquote page, but you can find it all over the web (and never directly referenced, at least in my brief search). Matt Deres (talk) 16:00, 27 March 2010 (UTC)

Another example is that pantheists believe that God is the Universe, or that there are ancient religions that regard God as a "spaceship" or an Anunnaki. Another proposition is that God created the Big Bang in an attempt to intertwine religion with modern science. ~AH1^(TCU) 16:37, 28 March 2010 (UTC)

dark matter

is it possible that dark matter,is/are,neutrally oscillating strings that are vibrating at the same frequency/pattern as the Universe itself.By this I mean,can strings blend into the background harmonic of an oscillating Universe?My thought is that such a string would only be evidenced through it's mass/ gravitational profile! —Preceding unsigned comment added by 122.107.53.106 (talk) 03:58, 27 March 2010 (UTC)

What do you mean by a spring? Dauto (talk) 04:04, 27 March 2010 (UTC)

The question refers to strings with a t, not springs. I assume this is intended to be analogous to the strings on a stringed musical instrument. Dolphin51 (talk) 08:03, 27 March 2010 (UTC)

I think string theory holds the vibrating strings in question. --Polysylabic Pseudonym (talk) 11:28, 27 March 2010 (UTC)

What does it mean for the universe to oscillate? --Tango (talk) 11:42, 27 March 2010 (UTC)

Also, what does "neutrally oscillating" mean? 129.234.53.144 (talk) 16:40, 27 March 2010 (UTC)

Maybe it means the oscillations cancel each other out, or they're vibrating at the background frequency of the universe (not sure how that would work)? ~AH1^(TCU) 16:30, 28 March 2010 (UTC)

F-CENTERS IN CRYSTAL DEFECTS

WHEN COMPOUNDS SUCH AS Nacl LiH are heated with high energy radiatin they became deficient in negative ion? 08:51, 27 March 2010 (UTC)Souravraaj (talk)

Air pressure drop

Could anybody point me in the direction of some of the general principles I'd need to work out the pressure drop of a gas through a hole in a sphere into a vacuum? Something designed for pedagogical purposes would be ideal. --superioridad ^(discusión) 10:37, 27 March 2010 (UTC)

I've read through fluid dynamics but it's a bit broad. --superioridad ^(discusión) 10:38, 27 March 2010 (UTC)

Obviously the pressure drop of the gas passing through the hole is from the starting pressure to zero (unless the vacuum is in another container small enough to be significantly pressurized by the inflow of gas). Are you asking about how quickly the pressure in the sphere will drop to zero ? If this is a rigid sphere, then the shape won't much matter (unless it was maybe a really long narrow tube). The shape, smoothness, and material of the hole could make a big difference, though. Laminar flow will be quicker than the turbulent flow which could result from a rough or uneven hole. StuRat (talk) 13:29, 27 March 2010 (UTC)

The pressure drop is known. Perhaps the OP wants to know the flow rate. Cuddlyable3 (talk) 16:09, 27 March 2010 (UTC)

Well, the question I've been given asks me to calculate the time for a particular percentage pressure drop, given an air-containing sphere in space that has a hole of known diameter punched in it. So, yes, rate of pressure drop is the one. Damned if don't have the least clue where to start, though. --superioridad ^(discusión) 00:48, 28 March 2010 (UTC)

Heya, sorry for the late response. This link might help, bottom of page 18 and the top of page 19 (about effusion). They're lecture notes from the first-year Chemistry course at Oxford; you'll get the most out of it if you know a bit of calculus but some formulae in the middle of p19 are calc-free. k_B is the Boltzmann constant. Hope this is of use. Brammers (talk) 13:24, 28 March 2010 (UTC)

Right, got it! Using equation 9.12, I think that if you set p₀ to 1 and p to whichever percentage you desire (where 1 is 100%, 0 is 0% and 0.5 is 50% etc), then plug in the right values to give you tau, you can solve for time. Have fun! Brammers (talk) 18:44, 28 March 2010 (UTC)

Well, the problem specifies that the hole is rather large (d=2 mm), so close, but no cigar (i.e. not an effusion problem). Link should be helpful, though, cheers. --superioridad ^(discusión) 22:34, 28 March 2010 (UTC)

In case it's not obvious, I should state that the flow rate through the hole will start out high, then gradually drop down asymptotically to zero. The pressure inside will be reduced in a similar fashion. StuRat (talk) 15:38, 28 March 2010 (UTC)

How do we make a bathtub full of lather and bubbles like how they show in the movies?

Have tried several times and failed, even after using the top end bath salts and shampoos I never never get a bathtub filled with lather and bubbles like how it is meant to be... whenever I try I can get scanty lather but not the real copious whitish romantic look. Is there a secret or am I missing something? I tried hot water, warm water, cold water, even tried increasing the lather by skimming the water with a mug, all this produces mere minimal increase and the water is good water, it isnt hard water or anything... have tried it even at the star hotels and failed.... Then asked room service to do it and they did a fabulous job but was too embarrassed to ask them how they did it. This anonymous behind the computer shelter gives me the neceessary courage to ask this question which has always been in my mind. And whats the scientific reason for me not getting anough lather? —Preceding unsigned comment added by Fragrantforever (talk • contribs) 12:55, 27 March 2010 (UTC)

It sounds like you're using the wrong stuff. Bath salts aren't meant to create suds, they are to soften the water. And shampoo creates minimal lather, as it's main purpose is to clean your hair, not make bubbles. What you need is called Bubble Bath: [1]. If you can't find any, then liquid dish-washing detergent is the next best thing. Pour it right where the faucet empties, then turn on the water full blast. The more you use, the hotter the water is, and the more turbulent, the more suds you will get. Also, avoid bath oils, as those will retard the suds. StuRat (talk) 13:03, 27 March 2010 (UTC)

The article is at Bubble bath. --Tango (talk) 13:10, 27 March 2010 (UTC)

That article starts off talking about bubbles in the water, as in a soda pop. Then they talk about a "foam bath", which is what we want, bubbles on top of the water. StuRat (talk) 13:20, 27 March 2010 (UTC)

If the OP has hard water she'll struggle to get a good head of foam. DuncanHill (talk) 13:26, 27 March 2010 (UTC)

Not with the right bubble bath. The stuff my family uses softens the water as well as making bubbles. Algebraist 13:30, 27 March 2010 (UTC)

When I was a kid, Mr. Bubble got results. --Mr.98 (talk) 15:21, 27 March 2010 (UTC)

I remember seeing a modelling session on tv where foam was being produced in a bath with an electric kitchen wisk or beater. Bubbling air through the water may also work. 89.243.43.75 (talk) 15:28, 27 March 2010 (UTC)

Jeanne Crain taking a Bubble Bath for Her Role in Movie. Cuddlyable3 (talk) 16:07, 27 March 2010 (UTC)

Water spraying at high velocity will create more foam than water running smoothly from the tap. A spray hose with a nozzle would thus do a better job than running the tap. Edison (talk) 19:11, 29 March 2010 (UTC)

What is the spin rate of a black hole?

We have 'clocked' pulsars rotation or spin rate. I have not found any reports of detecting a black hole's rate of spin, and I guess this may be because they emit nothing we can detect as yet. I was told that a black hole is a quasi-stellar object(Quasar? -Idunno) and so could not be clocked. By analysis of probable mass and the surrounding environment(a galaxy?) have we been able to take an educated guess at the spin rate of any black holeHebegb2 (talk) 14:55, 27 March 2010 (UTC)

While the objects falling into the black hole may spin in, I'm not sure the singularity itself has a spin. Since it's a single point, with no "lever arm", how would a spin be defined ? StuRat (talk) 15:42, 27 March 2010 (UTC)

Elementary particles have spin, despite being considered point particles. See rotating black hole. Conservation of angular momentum means a rotating star cannot collapse into a non-rotating black hole. --Tango (talk) 16:39, 27 March 2010 (UTC)

I thought elementary particles where more correctly modeled as "probability functions" than as point singularities. Maybe the same is true of black holes, since they have a certain uncertainty in position (which allows them to evaporate). Is that the explanation, or am I just applying Euclidean geometry and Newtonian physics to a realm where neither applies ? StuRat (talk) 17:53, 27 March 2010 (UTC)

I think the short answer is that it is complicated! In the Standard Model, elementary particles are considered point particles, although mathematically they are modelled using Quantum field theory where the concept of a particle doesn't really occur. I don't think that is relevant to the question of how they spin, though. The angular momentum of a particle is, like the angular momentum of a black hole, just an arbitrary constant in the equations that happens to obey the same conservation laws as angular momentum in other situations, so we call it angular momentum. (This apparent coincidence probably has an explanation, but it isn't part of our theories as far as I know - hopefully we'll work it out sooner or later.) Hawking radiation isn't really to do with uncertainty in the black hole's position (incidentally, I don't think the position of the singularity is really defined - it is just "in the future" - it is the position of the event horizon that we talk about), it's more to do with uncertainty in the energy density (I may be using the wrong term there, but in my intuition it is energy density) just outside the event horizon which allows particle-antiparticle pairs to be spontaneously created and then fail to annihilate. --Tango (talk) 23:39, 27 March 2010 (UTC)

I have heard that before about spin being only a theoretical concept when it comes to subatomic particles, not actual physical rotation of the particle. But, that does bring up the Q about what happens to the conservation of angular momentum in a black hole's singularity. If it's an infinitely small point, then even if it spins infinitely fast it still wouldn't have any angular momentum. Sounds like an argument for it not to be an infinitely small point, to me. StuRat (talk) 15:29, 28 March 2010 (UTC)

The black hole is not infinitely small. The event horizon has a radius. The angular speed people are talking about here is the top angular speed of the ergosphere which BTW doesn't spin as a solid body. see Kerr metric#Frame dragging. Dauto (talk) 18:51, 28 March 2010 (UTC)

But we're talking about the singularity, not the whole hole. If there's any mass to the singularity, then how is conservation of angular momentum handled there ? StuRat (talk) 19:46, 28 March 2010 (UTC)

The Kerr metric singularity is shaped like a ring instead of a point so there is no contradiction there either. Dauto (talk) 21:34, 28 March 2010 (UTC)

So, in that model there is no singularity ? StuRat (talk) 21:48, 28 March 2010 (UTC)

Yes, there is a ring shaped singularity. Dauto (talk) 22:23, 28 March 2010 (UTC)

Not too surprisingly, we have an article: ring singularity. Dauto (talk) 22:36, 28 March 2010 (UTC)

That looks to be exactly what I was talking about, an alteration of the point singularity model to allow for angular momentum. StuRat (talk) 22:43, 28 March 2010 (UTC)

The black hole in the GRS 1915+105 binary system rotates at approximately 1,000 revolutions per second. Gandalf61 (talk) 16:22, 27 March 2010 (UTC)

One nitpick: Quasars contain black holes as an integral part of them, but not all black holes are part of a quasar. Buddy431 (talk) 19:07, 27 March 2010 (UTC)

A claimed measure of the ergosphere of a particular black hole has been done recently. If it stands up, this would be the first measurement of the angular momentum of a black hole ever done. 20 points to the person who can locate the reference of which I'm speaking. ScienceApologist (talk) 03:16, 30 March 2010 (UTC)

Flying Black Holes

Assuming Black Holes are the only cosmic devices that eject matter and energy at their North and South poles presumably in exactly the same amounts and these beams of energy could be diverted at 90 degrees to the same perpendicular would the beams create a thrust that would send the Black Hole flying? 71.100.3.207 (talk) 16:52, 27 March 2010 (UTC)

Your premise is impossible, so your question is meaningless. The jets have to go in opposite directions in order for momentum to be conserved. It is conservation of momentum that makes rockets work (which seems to be what you are basing your result on). You can't ignore conservation of momentum when creating the jets and then use it for propulsion. Your physics would be inconsistent. If you have an inconsistent theory, anything can happen. --Tango (talk) 16:58, 27 March 2010 (UTC)

You are misunderstanding the question (my fault). The jets would be diverted to facing in the same direction like two side by side rocket engines. 71.100.3.207 (talk) 17:14, 27 March 2010 (UTC)

In that case, I think the black hole would stay still, and whatever device you used to divert the jets would get blown in the opposite direction as the redirected jets. StuRat (talk) 17:37, 27 March 2010 (UTC)

No, that's what I understood. It's impossible. That's just not what the jets do and they can't do that without violating the laws of physics. Unless you mean diverting them after they have left the black hole, in which case it won't have any effect on the black hole since there is no connection to it (but whatever is doing the diverting will be pushed away diagonally away from the black hole and in the opposite direction than the rays end up).

Also note that black holes are not the only cosmic objects with jets. For example, pulsars have them, too. StuRat (talk) 17:43, 27 March 2010 (UTC)

this paper : http://arxiv.org/abs/0908.1803v1 suggests the possibility of using (very small) black holes for propulsion, by focussing the hawking radiation in a certain direction (the radiation is analogous to the rocket exhaust of a classical rocket). 83.134.166.44 (talk) 18:22, 27 March 2010 (UTC)

The jets are sent at opposite directions not because of momentum, but because the object is spinning, and the jets emit from the poles. Momentum can be easily conserved no matter the direction of the jets because the material being emitted acts as the other half of the conservation law. If you had some sort of method of attaching a redirector to the black hole (which you don't, but if you did) then you could send the black hole flying through space. But it wouldn't fly very fast because the black hole is heavy and the jets are pretty light (pun accidental, but enjoyed). Ariel. (talk) 01:25, 28 March 2010 (UTC)

To try and make the fault in the question clearer... The "deflectors" the questioner is suggesting will be off in space somewhere. So, this is like asking if you squirt a water gun at an angled wall, will it make the water gun fly out of your hand? Once the exhaust leaves the black hole, redirecting the exhaust will not affect the black hole - with the exception of redirecting it back into the black hole. What is required is a means of attaching the deflectors to the black hole. Then, the deflectors will attempt to move, but being attached to the black hole, will end up moving the black hole also. As mentioned, the black hole is too massive to move, but simply attaching deflectors to one will be hard enough - no need to worry about moving something so massive. -- kainaw™ 02:26, 28 March 2010 (UTC)

My God can noone understand him? Yes, if you had some devices deflecting the beams of matter at 90 degrees, and those devices where somehow attached to the black hole, then it would move. Although that's not possible.--92.251.136.245 (talk) 22:14, 28 March 2010 (UTC)

You can't connect something to a black hole. It's a logical impossiblity. Nothing crosses the event horizon. You could just keep the jets a little in front of the black hole and move it gravitationally, or divert one of the jets back into the black hole to move it. — DanielLC 06:32, 29 March 2010 (UTC)

As I acknowldeged. Have you no imagination? I will never be overlord of the whole world, that doesn't stop me talking about what I would do if I was.--92.251.191.108 (talk) 00:27, 31 March 2010 (UTC)

Salty garlic

Back when I was eleven, I made some mash.

One batch had some garlic in it. It tasted pretty plain.

The other batch had the same quantity of garlic, and some salt. It tasted very garlicky.

How/why does salt make garlic taste stronger? Vimescarrot (talk) 17:38, 27 March 2010 (UTC)

It works for sugar as well (although sweet garlic would be pretty nasty). The general principle is that a flavor consists of an odor combined with a taste. Most of the information is in the odor component, but the flavor system needs to avoid being activated by pure odors, because pure odors frequently don't come from things in the mouth. The mechanism that makes this work is a strong nonlinear interaction between tastes and odors -- the presence of a taste strongly potentiates responses to odors. (Sweet and salty have stronger effects than sour and bitter, though.) This interaction is very well understood by cooks, who are systematically taught how to use salt and sugar to enhance the flavor of herbs and spices, but it's hard to find straightforward accounts of the science behind it. Looie496 (talk) 18:54, 27 March 2010 (UTC)

If I'm understanding this right, could I stick my nose in some crushed garlic, lick a small quantity of salt, and by doing this taste garlic? Vimescarrot (talk) 20:00, 27 March 2010 (UTC)

Yeah, though you probably don't need the salt at all. Your taste buds only receive info on whether something is sweet, salty, sour, savory, or bitter; what you perceive as "garlicky" is a small amount of sweetness mixed with aromatic compounds you sense in your nose. See flavor and taste for a fuller explanation. Matt Deres (talk) 20:18, 27 March 2010 (UTC)

That actually sounds like it could be a fun party trick, at an admittedly rather odd party. A friend is going to test it when he gets his daily dose of salt. Vimescarrot (talk) 21:21, 27 March 2010 (UTC)

suddenly I understand why you can find garlic salt at almost every supermarket... --Ludwigs2 22:37, 27 March 2010 (UTC)

Well, if it's tricks you want... Take an apple and cut out a small chunk of it - say 1cm x 1cm x 1cm or something. Cut out a similarly sized piece of onion (or even a garlic clove). Blindfold your friend and pinch his nose shut with a clothespin or something similar. Have him open his mouth and stick out his tongue and place one of the chunks right on there. By removing the "aroma" portion of the "flavour", your friend will have to use only "taste" to determine what's sitting on his tongue - and onions and apples "taste" roughly the same - only the aroma part is significantly different. Chances are good he won't be able to tell the chunks apart. Matt Deres (talk) 00:12, 28 March 2010 (UTC)

Ooh, and here's a somewhat related... well, not a "trick" per se, but a neat tip. Next time you make up a cup of hot chocolate, shake in a couple of sprinkles of cayenne pepper. Just a shake or two will do it. Oddly, the beverage won't taste hot at all, but rather chocolate-yier. The capsaicin in the cayenne bonds with your taste buds rather indiscriminately, boosting the flavour. The compounds in the cocoa (the milk solids) prevent the drink from getting spicy (assuming you don't dump a whole lump of cayenne in there), though it may get slightly bitter if you put too much in there. I know, it sounds nuts, and until I tried it, I didn't believe it either, but it really does work and it will improve the flavour of your cocoa. Matt Deres (talk) 00:23, 28 March 2010 (UTC)

I saw some chili chocolate on sale at my local farm shop yesterday but was too chicken to try it! --TammyMoet (talk) 08:00, 28 March 2010 (UTC)

It's nice, although not to be recommended for people that don't like spicy food! --Tango (talk) 22:18, 28 March 2010 (UTC)

Hydrogenation of vinyl chloride

Do you know:

• at which temperature and pressure vinyl chloride is hydrogenated?
• what kind of catalyst I can use to do it?
• what value of conversion can I achieve?
• some link that explain it?

--Aushulz (talk) 17:58, 27 March 2010 (UTC)

Google scholar gives to the question:'Hydrogenation of vinyl chloride -poly the answer Vinyl chloride is cleanly hydrogenated to ethane at 120" and 3 atm pressure in a PtCl2 solution in molten (C2H&N SnC13. in doi:10.1021/ja00780a013 --Stone (talk) 18:26, 27 March 2010 (UTC)

It depends on what you are trying to reduce it to. Are you trying to make ethane (see above), or chloroethane? 24.150.18.30 (talk) 18:47, 27 March 2010 (UTC)

This one suggests rhodium might be the catalyst of choice. doi:10.1021/jo01024a045--Stone (talk) 19:21, 27 March 2010 (UTC)

@24.150.18.30: I am trying to eliminate insaturation of VCM, producing preferably chloroethane, but the production of ethane (or other substances) it's however better than don't reduce VCM at all.

@Stone: I don't read nothing about vinyl chloride on doi:10.1021/ja00780a013; it's written in the first page? --Aushulz (talk) 22:05, 28 March 2010 (UTC)

It won't be using H2 gas, but why not a hydride donor like sodium borohydride? A vinyl chloride is an activated Michael acceptor, right? John Riemann Soong (talk) 04:49, 29 March 2010 (UTC)

I suppose sodium borohydride is more expensive than hydrogen, so I exclude this possibility. --Aushulz (talk) 13:25, 29 March 2010 (UTC)

A vinyl chloride is not a good Michael acceptor: chloride cannot easily stabilize a lone-pair/anion at the carbon to which it is attached. For example, the haloform reaction does not release the carbanion until you get three halides on the carbon, and attempts to deprotonate halocarbons often lead to carbene-like structures (α-elimination). Vinyl chloride is fairly inert to hydride attack, stable enough that NaBH₄ can reduce other things in its presence quite selectively (U.S. patent 5,068,474). DMacks (talk) 14:16, 29 March 2010 (UTC)

Re cost -- in my experience hydride donors are cheaper to implement at the laboratory scale than pressurised H2 with expensive metal catalysts. Of course, if you want economy of scale at the industrial level, you want catalytic hydrogenation, but still. Thanks for the heads-up, DMacks. John Riemann Soong (talk) 02:59, 30 March 2010 (UTC)

If your tongue was removed...

which, if any, speech sounds would you still be able to pronounce recognizably? 69.107.248.69 (talk) 21:47, 27 March 2010 (UTC)

Vowels. Some of the Labial consonants would also be able to be sounded without the tongue. --Jayron32 23:44, 27 March 2010 (UTC)

You couldn't distinguish all vowels - the tongue is needed to control the frontness of the vowel. --Tango (talk) 23:58, 27 March 2010 (UTC)

It would also depend on how much of the tongue is removed... --Jayron32 00:32, 28 March 2010 (UTC)

I'm assuming the tongue has been severed at the root, and the rest of the vocal system is undamaged. 69.107.248.69 (talk) 16:52, 28 March 2010 (UTC)

The glottal stop and /h/ would also be still pronouncable. Since nasality is triggered by the lowering of the velum (rather than the raising of the tongue towards the velum), /m/ would be one of the possible labial sounds. — Ƶ§œš¹ _{[aɪm ˈfɹ̠ˤʷɛ̃ɾ̃ˡi]} 03:59, 29 March 2010 (UTC)

Yawning

Why do i tend to yawn a lot just before i get a bad cold? YAWN!--79.76.129.127 (talk) 23:22, 27 March 2010 (UTC)

Before you get a bad cold or during? You may find Yawn#Proposed causes useful. --The High Fin Sperm Whale 23:39, 27 March 2010 (UTC)

A likely explanation would be that when you're run down and tired, your immune system isn't as effective as it is when you're completely refreshed, and thus you are more likely to catch a cold which presents with symptoms (i.e. not killed in time to avoid the symptomatic stages of the common cold). It's not so much that yawning shows that a cold is coming, but instead that fatigue can increase the likelihood of you not removing a cold from your body before the symptomatic period. Regards, --—Cyclonenim | Chat  23:54, 27 March 2010 (UTC)

Just before I realise its a bad cold coming on.--79.76.129.127 (talk) 23:54, 27 March 2010 (UTC)

That's possible, but it could be tiredness caused by the cold. It takes several days after you catch a cold before you develop cold symptoms, but your immune system is working hard in that time fighting the cold. It seems plausible to me (and fits my own experience) that your immune system working hard can make you tired. --Tango (talk) 00:00, 28 March 2010 (UTC)

Missed beats

Is there one main cause for missed heartbeats, or are there a number of different possible causes?--79.76.129.127 (talk) 23:36, 27 March 2010 (UTC)

Not sure what you mean by "missed heartbeats". There are several different conditions which could be described as such. See tachycardia, bradycardia, Palpitation, or Cardiac dysrhythmia for articles dealing with abnormalities in heartbeat. The article Cardiac cycle discusses the normal heartbeat. You should be able to find the information you need in those articles. If you are personally concerned about your own heartbeat, find a physician who can see you in person and find out what is wrong with you; random strangers on teh intrewebz are unlikely to be able to provide a good diagnosis. --Jayron32 23:41, 27 March 2010 (UTC)

No. What is perceived as "missed beats" are usually premature ventricular contractions, usually a rare and harmless phenomenon in young healthy people. In frequent runs, or in other clinical contexts, they may signify more of a problem. alteripse (talk) 04:26, 28 March 2010 (UTC)

missed beats can also be idopathic and be harmless with no clinical significance213.130.123.12 (talk) 05:17, 30 March 2010 (UTC)

While missed heartbeats may not mean much, they may also be an indicator for AV block. More info would be medical advice. This situation should be dealt with a physician in person. Nobody can or has the right to make a diagnosis on a message board. 88.242.231.192 (talk) 10:42, 30 March 2010 (UTC)