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Does Antimatter Fall Up Or Down?
KentuckyFC writes "There are enough loopholes in the general theory of relativity to allow antimatter to fall up rather than down in a gravitational field. We've never been able to make enough of the stuff to do the experiment. But at the European particle physics laboratory at CERN, where scientists have been refining the technique for making antihydrogen, researchers are designing an experiment called AEGIS that will finally settle the matter. The idea is simple — fire a beam of antihydrogen atoms and watch which way they fall — but the details are fiendish (abstract). The answer should help solve a number of important conundrums such as why there is so little antimatter in our part of the universe and what the value of the cosmological constant is."
It's a cool experiment, but it's news once you get the result, not "a few years" before.
Unless they're trying to drum up interest for funding...
Forget thrust, drag, lift and weight. Airplanes fly because of money.
There's a big difference between a belief that something is most likely true, and an experiment that removes all doubt.
09F91102 no, 455FE104 nope, F190A1E8 uh-uh, 7A5F8A09 that's not it, C87294CE no. Ah! 452F6E403CDF10714E41DFAA257D313F.
Yes, Silly physicist PhDs doing unneccesary experiments. They could have been told the result of the experiment just by asking a random commenter on Slashdot. :)
:P
Because our understanding of physics is so consistent that it is a waste of time to test the cornercases of our theories *cough*quantum gravity*cough*dark matter*cough*dark energy*cough*
And science is all about the difference between "I think..." and "I've tested..."
If it behaves exactly as predicted, you can make another mark and continue. If not, you've found something potentially very important.
Assorted stuff I do sometimes: Lemuria.org
Antimatter *could* be different because the mathematics of GR allow it, and we haven't actually done the experiment before. I wouldn't put much faith in human intuition in these matters, considering how counter-intuitive entire GR is...
;-)
I mean, we see water falling off edges of waterfalls etc. Why should the edge of the world be any different?
Shouldn't that mean that matter-antimatter annihilation would result in no energy being emitted? If antimatter had negative mass, the net mass converted to energy would be zero.
He who lights his taper at mine, receives light without darkening me.
Until now I thought that ouside the real of mathematics (where things can be proven and no further revision is possible, save for attacking the logic of the proof), there is no such thing as "an experiment that removes all doubt"?
Ezekiel 23:20
If that were true, while it would have no practical use in the near future
Not necessarily - Merely opening that particular conceptual door would lead to a massive influx of funding and revisited anomalous past results.
Interesting thing about experimentation, even the most honest of researchers tends to throw away "bad" results (in the sense of not publishing them, not in the academically-dishonest sense of omitting them from the data). If the scientific community suddenly accepted the possibility of spooky-effect-X, you can bet that dozens or even hundreds of research groups would dredge up their past efforts to see if effect-X explains their results.
Case in point, l'Acedemie des Sciences and meteorites. Up to the turn of the 19th century, only idiots would dare claim that rocks could fall from space... Until the scientific community decided they could, at which point a huge body of past evidence appeared practically overnight supporting the existance of such falling objects.
Did it really take 65 physicists to decide that the best way to test gravitational effects was a particle beam deflection? I suppose simplicity is nice, but I honestly expected something more complicated with that many collaborators...
Because all the other properties of antimatter that have been tested so far are different unlike every type of normal matter ...
...
This is a Black Swan problem
Theory : All Swans are White
Proof : every swan I see is white, every swan
Problem : Australia was then discovered along with the black swan.....
Puteulanus fenestra mortis
What? no. The matter would not follow, it would be repelled. Think of two magnets with north pointing at each other.
It's not science. Even doing a nice bunch of calculations and saying "Well this shows that anti-matter should do this," is not science, or at least not the important part. Science is testing beliefs by experiment. So regardless of what we think anti-matter will do, and regardless of how sure we think we are, we still need to test it. That's how science works. You come up with an idea, you test it. If the test falsifies it, you come up with a different idea and test it. If the test supports it, you come up with more tests to try and falsify it.
Through this process, we come to understand the natural world, and come to be fairly certain that our understanding is correct. Math and theoretical work is great, but actually testing those theories is what makes science what it is.
So even if we are 99.999999% certain that our calculations are solid and anti-matter does something, we still need to test it. There are plenty of things that we've been certain about that, when we tested it, turned out not to be the case.
If the 2 possible outcomes are polar opposites, and it goes one way and not the other. I'd say "removes all doubt" is a fair statement. Note I didn't use the word "prove", more like doubt in the legal prosecution sense.
But now were just arguing semantics. Oh wait, this is /. never mind.
09F91102 no, 455FE104 nope, F190A1E8 uh-uh, 7A5F8A09 that's not it, C87294CE no. Ah! 452F6E403CDF10714E41DFAA257D313F.
Are you sure you have a degree in physics? Neutrinos have no charge, and thus are not affected by electromagnetic fields. The name sounds like "neutral" because of this. If they were charged they would be called something else.
If you mod me Overrated, you are admitting that you have no penis.
They missed one option. What if antimatter is not affected by gravity? I'll put my money on falling down.
I think you are confusing molecular energy with anti-gravity.
TFA questions whether anti-matter will be attracted (mass-> <-mass), or whether it will be repulsed (mass<- ->mass) by gravity.
Hydrogen is attracted rather than repulsed by earth's gravitational pull. Whether the earth's gravity well is deep enough to keep hydrogen captive is a separate topic. Having enough energy to escape earth does not mean that it is repulsed by earth's gravity. The Space Shuttle has enough energy in its fuel tanks to reach escape velocity, and there is no doubt that is is attracted, not repulsed, by earth's gravity.
Hot air is still attracted by earth's gravity. However, its higher energy state forces it to occupy a larger volume at a given ambient pressure, which makes its density lower than the surrounding cooler air. Hot air doesn't defy gravity by rising; cool air pushes the hot air up because it is denser.
I prefer rogues to imbeciles because they sometimes take a rest.
Yes I would be arguing that the earth would also be accelerating however infinitescimally quicker towards the other object. I know that the differences are purely academical and have pretty much no bearing in real terms, but consider you had 3 different orbs of the same volume but different masses, say A=1 large mass unit, B=2 large mass units and C=1 large mass unit.
If you left any of these orbs near each other in space then they would exert a significant gravitational pull on each other and would both be accelerated towards each other. A and B would accelerate towards each other at the same rate as B and C. A and C would accelerate towards each other slightly slower. I don't see how relativity makes much of a difference in that case, it's basic newtonian stuff. For relatively small masses next to a large mass then the gravitational pull that they exert is negligible compared to the pull of the large mass, but technically it is still happening. You can argue about relativity if you want, but observing from a place standing on earth watching 2 very large moons accelerating towards the earth, I'm pretty sure the more massive moon would appear to impact first to the observer.
which is totally what she said
Next time you've got a balloon, put it in the car and give this experiment a try. When you have a helium-filled balloon in the car, it reacts opposite to the way most other things in the car react. When you slam on the brakes, a ball on the floorboard will roll forward, but the balloon will float backward.
Sure, when you slam on the brakes the balloon wants to go forward, but so does the rest of the air in the car's interior. Since the air is more dense than the helium-filled balloon, it wins out and pushes the balloon backward.
You got me there to an extent, but with a loosely-inflated mylar balloon, the pressure can be equal between the interior and exterior of the balloon ... in either case you're right that "relative vacuum" was not really valid. My original point was that the helium means there's less mass in the same amount of volume, which was the point of my original "hole" analogy.
Hydrogen in the atmosphere does not 'fall up'. It's pushed up; it's called buoyancy. Hydrogen molecules at sea level are on average moving at less than 1/4 of Earth's surface escape velocity.
And do you honestly think that these physicists are going to be so stupid as to not do their antimatter experiments in a vacuum? That's about the only conditions where you could measure the rate of fall of individual atoms.
Don't just stand there, get that other dog!
Yes, for practical purposes QM is fine - but it is not enough for understanding. It's like the difference between engineering and science; engineers are good and worthy people, but their focus is practical: the construction of things, the application of knowledge to a practical purpose. The focus of the scientist is on the unknown, the unanswered questions; the practicality of things is not foremost in their mind, they speculate and grope in the dark. These are of course wild generalisations, but the principle of what I just said is sound, at least
And thus I find that the proper scientific attitude to QM is not "Who cares, it works", but "Why does it work?" - there must be something better out there, a theory of which QM is just a special case, an approximation. Scientific method relies, after all, on theories being falsifiable - isn't that, more than anything, the very embodiment of "Why not"?