http://www.badastronomy.com/phpBB/viewtopic.php?t=22041
In the "Against the Mainstread" forum I posted a response to the June, 2005 cover article of Discover magazine. It's controversial, which is why I didn't put it here first. The article asks why a person can't be in two places at once if they are composed of tiny particles, and each of those tiny particles can be in two places at once.

The article says that Sir Roger Penrose has answered the question. He talked around it quite a bit, but hasn't really answered it. He's got an experiment going though that might answer it in another four years.

My response dealt with what the issue of observation means for localizing a particle. I posted at a couple of orther astronomy forums, but did not really expect a knowledgable reply. I was not disappointed. I also posted here at the Bad Astronomy forum and did expect some thoughtful criticism, but so far I have indeed been disappointed. Either the brains of this board have not noticed the thread entitled "Two Place Electron", or they are still thinking about it.

The significance of my reply to Discover is not to tell them that Penrose will not be going anywhere; they already knew that. While talking though the problem, gravity became a prediction of the quantum mechanics solution.

Some of the people posting here are well-versed in quantum mechanics. I really would be curious to know if I have missed something. I have already sent the response in "Against the Mainstream" to Discover magazine. I was hoping you people might give me your opinion as to its merit.

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There are ten kinds of people. Those that understand binary, and those that do not.

I read your response and I think its very well thought, Being just a mechanic I don't have the background to advise you either way tho.

Perhaps you could offer up this to another board as well (to get a varried response)

Try here:

http://www.physlink.com/Community/Fo...s.cfm?Forum=17

If you have a hypothisis with hole they will definately let you know! Beware, You may not like the results...

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I read the Discover article. This is the way I wrap my mind around it:
Suppose that you "throw" a particle. There is a probability function that describes the likelyhood that it will land in a given spot. If the function is independent of mass, then, in relation to its diameter, a baseball will land exactly where it "should", but an electron, in relation to its diameter, will land just about anywhere.

Does this make sense?

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T. Anderson

I think I read Maddad's post, but lack of time and brainpower kept me from posting a reply.
However, I got the impression that Maddad's is basically the same as decoherence.
At the moment this is the most "fashionable" concept in modern research to explain how we go from quantum world to classical world.
The concept in a nutshell is this: the high number of interactions with other particles, result in the collapse of the wavefunction of a particle, and hence classical behavior.

Of course, I might have misunderstood the original post.

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papageno


"Why waste time learning, when ignorance is instantaneous?" - Hobbes (Calvin and Hobbes)

"It's all about context!" - Vince Noir (The Mighty Boosh)

"I've never heard of such a brutal and shocking injustice that I cared so little about!" - Zapp Brannigan (Futurama)

One thing that troubled me a little was that the observers of the Penrose particles were all Penrose particles. It's hard to think of an electron in Penrose's toe, observed, say, by a particle in Penrose's ear somehow more worthy of consideration than the same particle observed by a particle in the blade of grass he is standing on.

If distance makes a difference, the grass particle is more important. If distance makes no difference, then all the matter in the universe is equally important.

It's not a deal-breaker, but I think all non-Penrose matter got short shrift in the tale.

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0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0....

That makes sense because if all of Penrose was in a Vacuum and not observed by the enviroment Penrose could observe himself but would remain quantum to the remainder of reality. Penrose observing Penrose makes Penrose solid to Penrose. If nothing else could observe Penrose except Penrose. Penrose needs the enviroment observing Penrose to make Penrose exist. Ok, Did that Make sense?

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Interesting you should bring this up; I was just talking to someone today about the possibility of deriving gravity from the QM wavefunction of a particle. Any ideas would be welcome. (I talking here about finding the source of gravitation in the wavefunction).

I did come across the Discover article the other day and was intrigued by the experimental set-up, any experimental test correlating quantum and gravitational effects are intriguing.

My first impression was to remember the COW experiment.
By diffraction through a crystal, the quantum particle, a neutron, was made to 'interfere with itself'; and it was shown that the effect of gravity was to change the PHASE of the neutron wavefunction.
I don't believe there is a change in the energy though; that would imply a change in wavelength which I don't think was evident. Someone else may want to comment on this experiment or its other implications.

Anyway, if I understand it correctly (and maybe I don't), the Penrose experiment seems to be an attempt at the COW experiment, albeit, in a different form... ??

G^2

I am not familiar with that experiment.
However, what you wrote would make sense if the neutron was kept at the same height throughout the experiment (which means that the Earth's gravitational field would not do any work on it and change its energy).
If the experiment has been performed for different heights, the interference pattern in the wavefunction can change, because the gravitational flux enclosed by the interfering paths has changed.

Probably the best analogy for this experiment, is the Aharonov-Bohm effect for an electron in magnetic field.

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papageno


"Why waste time learning, when ignorance is instantaneous?" - Hobbes (Calvin and Hobbes)

"It's all about context!" - Vince Noir (The Mighty Boosh)

"I've never heard of such a brutal and shocking injustice that I cared so little about!" - Zapp Brannigan (Futurama)

I guess I shouldn't take too much liberty in abbrev. :wink:
The 'COW exper.', as it is sometimes named, (after its author's initials... Colella, Overhauser, and Werner -1975), was the neutron interferometry exper. that revealed the relative phase change due to a gravitational potential.
And you are correct, one of the arms of the interferometer was rotated into a higher gravitational potential, revealing a phase change.

I guess you could say it (COW experiment) is the gravitational analog to the Aharonov-Bohm effect (AB effect) where there is a phase change in the particle's wavefunction due to a change in the electromagnetic vector potential.

However, I still can't see how or why the Penrose experiment would be expected to work (see his diagram in Discover) since there is NO change in the gravity potential. He seems to think GIVEN ENOUGH TIME (1 second) then the tiny mirror can change 'states' . Duhh? :-k What am I missing?
He says, 'Gravity forces the tiny mirror into a single state'. Well, since the experiment doesn't eliminate gravity on the mirror, it is already in a single state! And you wouldn't be able to observe it transiting from a double state to a single state. ??? What am I missing?
If its simply a matter of allowing enough time, then when do you start 'timing'? It's in the same gravitational potential the whole time!
Help, Steven Hawking! He's doing it again! #-o

G^2

By the way, Papageno, I agree with your view (original post) that a phenomena called 'decoherence' is fundamentally responsible for the difference between classical and quantum effects. It's not really the 'size' or diminesions that 'cause' the difference.

We have wonderful examples of macroscopic quantum systems with full blown macroscopic quantum effects. I'm referring to the quantum fluids in a superconductor, for example.In the superconducting state, there is no 'decoherence'; one wavefunction extends across the entire size of the superconductor! proving that dimensions are not as fundamental as one may think.
Also, I think gravitational effects should be evident in the phase of the supercurrent for example, and it seems to me it would probably make a far better test bed for these quantum/ gravitational interactions.

G^2