is an electron everywhere at once?

steersman

Is an electron everywhere at once within a waveform?

steersman

and what about a photon?

MathematicalPhysicist

it's probablity dictates the electron to be in other places rather than the one observed by the experiment, the experiment affects the state of an electron (which is in a superposition).

steersman

cheers loop

Tom Mattson

That cannot be said with any certainty. It is just one untestable interpretation of quantum theory, and I for one am inclined to think it is false.

Check out this thread by loop quantum gravity:

http://www.physicsforums.com/showthr...&threadid=9661

dlgoff

When bound in an atom their location can be narrowed to a probability density distribution depending on its energy state. However, within the distributions, HUP still applies.

Corrections encourged.

Tom Mattson

The probability distributions are infinite in extent, so saying that the HUP applies "within the distributions" is just another way of saying that the HUP applies everywhere.

Thallium

Isn't this related to Schrödinger's cat mystery?

dlgoff

Tom,

So even as part of an atom, the electrons probability distribution is everywhere? What about the wave equation solutions for the hydrogen atom for example. I thought that they described various symetrical distribution patterns that are localized (i.e. depending on the its quantum numbers).

Tom Mattson

Yes.

Take a look at the solutions. They only go to zero asymptotically, at infinity. That means they are nonzero everywhere.

You probably got that impression from looking at those famous 3d polar plots of atomic orbitals, that seem to have definite cutoff points. The thing is, those pictures are generated by imposing a cutoff. That is, they determine the orbital which contains, say, the innermost 90-95% of the probability density, and draw that. To go to 100% would require an infinite amount of space.

The atomic electrons are "localized" only in the sense that their probability densities approach zero as r approaches infinity. The only way to truly localize a particle to a finite region of space is to confine it in a potential well whose walls are infinitely high (on the energy axis). This, of course, is not physically realizable.

Tom Mattson

Yes. The idea is that you do not know exactly where the electron is until you measure it. Since you can only know the result of a measurement, it leaves open the (untestable) interpretation that, inbetween measurements, the electron can be in more than one place at a time, though it does not imply that. The absurdity of such a position was highlighted by Schrodinger with a "quantum cat" that was at once, both dead and alive.

Thallium

I read an article a few months ago about this "riddle". Sir Roger Penrose wanted to prove that Schrödinger was right. That an electron can be in two places at once. To me however, this sounds more like a metaphysical idea.

dlgoff

Thanks Tom. I should have thought before asking. But I'm glad I did since you have explained very well whats going on.

Thanks again,

pelastration

Maybe Penrose looks for such explanation to prove some of his metaphysical ideas. It shows that measurement problems of an (egocentrical) observer influences his general perception of the reality of the world. The same absurdity is like some people say that the tree that falls in the wood without an observer doesn't makes a sound.

Thallium

That sounds more like surrealistic poetry[:)]

notwithstanding

Penrose misinterprets the frequency of the particle with the particle itself. Notwithstanding any logic to the contrary.

DrChinese

Doesn't seem all that absurd, really. No different really than the Aspect experiments. I.e. assuming that quantum particles have discrete values when not being watched, which we now know cannot be demonstrated. I would call that the equivalent of the tree in the forest, what would you call it?