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Gravity's quantum leaps detected
New Scientist ^ | 19:00 16 January 02 | Hazel Muir

Posted on 01/17/2002 4:06:29 PM PST by Ernest_at_the_Beach

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To: monkey
Math guy ... you with Clarity or agin' him?

nature makes particles behave according to curiously rigid rules.

Huh ... doesn't sound at all like that Gaia chick.

41 posted on 01/17/2002 10:11:21 PM PST by Askel5
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To: editor-surveyor
Biscuits and gravy? See you for breakfast!
43 posted on 01/17/2002 10:27:34 PM PST by Askel5
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To: Physicist
Correct me if I'm wrong, but this experiment, standing on it's own, proves nothing. It shows only that the neutrons posessed a minimum amount of energy that caused them to rise more than 14 micrometers above the mirror. Let's say 10 neutrons reached the detector. To prove a quantum effect, there should be no increase in the number of neutrons detected until the mop is set at a greater, discreet height. So, there will be no increase in neutrons detected until the mop is set to 30 micrometers, for example. At that point, the number of neutrons detected suddenly rises. For example, it becomes 15. Then, the mop is elevated again. No more neutrons are detected until the mop reaches another discreet height. Maybe that is 35 micrometers. Then, 18 neutrons are detected. That would show a quantum effect.

This study also depends on the gravitational field of the Earth for it's results, and should be replicated in greater and lesser gravitational fields for confirmation. Is that right?

44 posted on 01/17/2002 11:19:09 PM PST by sig226
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To: RadioAstronomer
Nesvizhevsky's team took a beam of ultracold neutrons with tiny energies, moving from left to right at less than eight metres per second. Under the force of gravity, the neutrons fell down onto a reflecting mirror and bounced off it before arriving at a detector.

The team could limit the energies of the neutrons arriving at the detector by placing an absorbing material at different heights above the mirror. The material mopped up all the neutrons that bounced too high.

At last, we know why the toast always falls buttered-side down. The butter mops up all the neutrons.

45 posted on 01/18/2002 2:41:47 AM PST by PatrickHenry
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To: Ernest_at_the_Beach
Heavy article, but Im only interested if these guys can figure out a way to build a neat gravity gun for the Special Forces.

All your gravity are belong to us.

46 posted on 01/18/2002 3:01:18 AM PST by ovrtaxt
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To: sig226
Correct me if I'm wrong, but this experiment, standing on it's own, proves nothing.

As I said, the primary value of this is the technique and not the result. They do claim in the article to have evidence for higher energy levels; presumably that will be the subject of their next publication.

This study also depends on the gravitational field of the Earth for it's results, and should be replicated in greater and lesser gravitational fields for confirmation. Is that right?

I don't know whether their apparatus is sensitive enough to distinguish variations in the gravitational field at different places on the Earth. It would be expensive to do it anywhere else right now. Personally, I think it's enough to show that the energies are discrete, and to show that the energy levels agree or disagree with what theory predicts.

48 posted on 01/18/2002 4:19:15 AM PST by Physicist
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To: Ernest_at_the_Beach
At the other end of the quantum scale (sort of), I wish they'd tell the world more about quantum redshift and the implications it has for the Big Bang.
49 posted on 01/18/2002 4:27:13 AM PST by aruanan
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To: PatrickHenry
Heavier objects falling faster than lighter objects?

I agree: if for no other reason, because the heavier object ATTRACTS the other body more, which will have a small but real velocity component up towards the falling object!

51 posted on 01/18/2002 8:56:42 AM PST by chilepepper
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To: laconas
maybe in some time they will able to measure the speed of gravity

A repeat in a way of the Thompson experiment where the charge on an electron was measured.

What is the speed of electrical attraction?

52 posted on 01/18/2002 9:02:01 AM PST by RightWhale
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To: Askel5
So you pigeonhole others ("math", "guy") and then declare yourself the queen of noncompartmentalized thinking. "Clever" "Girl".

I agree that this experiment doesn't directly address other energy levels (although it handles the edge condition). The effect will be less at higher energy levels. As an analogy, the two-slit experiment (the hypothetical, intro quantum theory experiment that shows that electrons appear to be in multiple places at the same time) is done with particles, where the effect can be noted, not baseballs.

Physical theories can be verified under different conditions, but not proven in the mathematical sense. Remember Mr. Spock's: "We may be in a region of space where our physical laws do not apply."

BTW, to show I'm not all "math" and "guy", I saw "The Music Man" recently. You came to mind when the mother blames her daughter's singleness on "her Irish imagination, her Iowa stubborness and her library full-of-books."

But I forget why.

53 posted on 01/18/2002 9:15:41 AM PST by monkey
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To: monkey
Oh man ... there's gonna be trouble in river city if and when my mother checks in to see what the clever monkey had to say this time.
54 posted on 01/18/2002 9:18:34 AM PST by Askel5
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To: Clarity
Well, I'm not sure what you're looking for in the way of proof, and I'm not sure what you mean by 'minimum necessary energy levels'.

The reason you can't tell that the energy of, say, a baseball is quantized is because the energy levels are so close together at that energy scale. In order to see the quantization, you need to look at extremely light objects that move slowly.

If the spacings were much, much farther apart, you might notice that while you can throw a baseball upwards at, say, 10 mph, which allows it to reach a certain height, you can't throw it upwards at 12 mph. Put a little more arm into it, and you can throw it at 14 mph, but not a little bit faster or slower than that. Put still more arm into it, and you can throw it at, say, 17.5 mph.

But yes, I suppose in the real world, you wouldn't be able to demonstrate energy quantization in the case of a baseball, since you'd never get the resolution you'd need. But lighter, slower objects do apparently behave in the counterintuitive way I described.

55 posted on 01/18/2002 9:22:33 AM PST by Physicist
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To: laconas
Right Whale: What is the speed of electrical attraction?

laconas: I don't think anybody really knows.

It's the speed of light. Virtual photons fly around at their accustomed speed, creating the electrical field in the space around them. The speed of gravity is thought to be the same, mediated by a so-far undetected particle called the graviton.

57 posted on 01/18/2002 9:42:20 AM PST by VadeRetro
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To: VadeRetro
Virtual photons

I know what a virtual image is. I have been an optical engineer in a prior incarnation. But I do not know what a virtual photon might be.

For the speed of gravity determination they are using massive but highly sensitive devices. If something heavy moves, like a supernova, they might be able to get a measurement. I think they are waiting for a suitable event so they can get some numbers. Until then they are detecting neutrinos and doing Aetvos experiments with artificial satellites. Maybe we will be the generation that gets a clue.

58 posted on 01/18/2002 10:11:23 AM PST by RightWhale
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To: chilepepper
Heavier objects falling faster than lighter objects? I agree: if for no other reason, because the heavier object ATTRACTS the other body more, which will have a small but real velocity component up towards the falling object!

Your opinion was once universally held; but experimentation has shown that heavy and light objects fall at the same speed. Each falling object is not only attracted to the earth in proportion to its mass, but it [the falling object] also has inertia that resists the motion, so the falling object's mass cancels itself out. All that's left is the earth and the gravitational constant, which are the same for all falling objects.

59 posted on 01/18/2002 10:27:02 AM PST by PatrickHenry
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