Individual quantum & its multi location at one & the same time

[chandragupta]

Is it true that an individual quantum exists anywhere & everywhere at one & the same time till it is observed & then at the very moment of observation it withdraws itself from this anywhere & everywhere & becomes one single particle once again at the site of observation? Your thoughts?

[derek w]

In quantum field theory,the fields exist everywhere.

[swansont]

Is it true that an individual quantum exists anywhere & everywhere at one & the same time till it is observed & then at the very moment of observation it withdraws itself from this anywhere & everywhere & becomes one single particle once again at the site of observation? Your thoughts?

"Withdrawing" is an awkward characterization. There is no defined position without the measurement.

[QuantumBullet]

You can think of a particle as having a Wave function, which extends to every spatial point in the Universe. Particular points on this wave correlate to the probability of finding the particle at a particular point in space.

Once you make an observation on the particle, you are effectively interfering with this wave function, and cause it to decohere, and hence it appears to be in a single point in space.

 

It can be said that, prior to this decoherence (and hence observation of the particle), the undisturbed wave function of the particle gives way to a small (but finite) probability that the particle can be found at any single arbitrary point in space.

[derek w]

But you can't travel faster than the speed of light,so there is something wrong with this interpretation of the probability function?

[J.C.MacSwell]

Is it true that an individual quantum exists anywhere & everywhere at one & the same time till it is observed & then at the very moment of observation it withdraws itself from this anywhere & everywhere & becomes one single particle once again at the site of observation? Your thoughts?

 

 

The clash is with relativity/simultaneity;

 

The problem is this "anywhere & everywhere at one & the same time" is frame dependant, yet consistency in all frames is still required. So which frames get to pull the plug on wave function "at one and the same time", and which ones must lag behind in some sectors of the frame while in fact anticipating it in others?

[spoirier]

The presence/absence of the particle at every position, is entangled with its presence/absence at every other position.

So the problem is to explain what is quantum entanglement.

I have described this in my introduction to quantum physics.

Edited December 20, 2012 by swansont
remove url

[swansont]

!

Moderator Note

spoirier, posting just to provide a link to your own site is prohibited. The url has been removed (here and in another post)