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Author Topic: How is the appearance and disappearance of particles in empty space measured?  (Read 2260 times)

Offline LetoII

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When it's said that particles spontaneously come into existance at a quantum level and then pop out of existance i asume this has been somehow meassured in a vacuum on earth. Is it also possible to view the same phenomenon in outer space and has this been done?
« Last Edit: 14/07/2012 10:16:35 by chris »


 

Offline Geezer

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Re: empty space at quantum level
« Reply #1 on: 12/07/2012 07:04:51 »
Although I don't think it makes any difference, it sort of depends on how you define outer space. Do you mean in the vacuum beyond the Earth's atmosphere?
 

Offline imatfaal

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Re: empty space at quantum level
« Reply #2 on: 12/07/2012 10:06:00 »
The effect you are describing is the Casimir Effect - you can measure a force between two very close uncharged metallic plates.  I am not sure if this experiment has been repeated in orbit - its a pretty tricky methodology and a sensitive experiment so possibly not.  It is assumed - for very good reasons - that the same effect will apply in "outer space";  if it doesn't apply in outer space then we lose the founding principle of relativity that physical laws are the same in all places. 

http://en.wikipedia.org/wiki/Casimir_effect
 

Offline Soul Surfer

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Re: empty space at quantum level
« Reply #3 on: 12/07/2012 23:06:20 »
Whilst it is true that the Casimir effect is seen as one of the proofs that the quantum mechanical vacuum consists of a vast array of virtual particles with their antiparticles that appear and disappear within the uncertainty limits.  The effect is due to the presence of a structure restricting the range of particles and antiparticles that could appear and disappear within a particular volume this means that the wider range of particles that can appear and disappear in an unrestricted space exert pressure on the restricted space. 
 

Offline CPT ArkAngel

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Re: empty space at quantum level
« Reply #4 on: 12/07/2012 23:19:43 »
What prevents your feet from moving through the ground is the EM force. EM force is mediated by photons. Are these photons real or virtual?
 

Offline distimpson

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Re: empty space at quantum level
« Reply #5 on: 13/07/2012 01:15:07 »
here's a recent preprint on the dynamic Casimir effect, kicking virtual photons loose.
http://arxiv.org/abs/1105.4714
« Last Edit: 13/07/2012 01:16:39 by distimpson »
 

Offline CPT ArkAngel

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Re: empty space at quantum level
« Reply #6 on: 13/07/2012 02:54:54 »
First, energy is always conserved.

Second, the mirrors are moving  relatively to the detector. This fast movements impart to the mirrors special properties in relation to the detector (see my theory in Lighter-Theory section).

Third, what happened when you cool down matter so it becomes a bose-einstein condensate? Particles can then pass through each other.
 
Conclusion: Those photons don't come from vacuum but from real matter (thermal radiation)... Or how do you cool down vacuum?  :o)

 

Offline distimpson

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Re: empty space at quantum level
« Reply #7 on: 13/07/2012 18:44:00 »
Well, I think it is a valid concern since there is no way to measure "empty space" without using some sort of matter/energy probe.

These folks http://www.extreme-light-infrastructure.eu/High-field_5_2.php are trying to detect vacuum fluctuations using laser scattering. But again, I guess you could argue that the space they are probing is not empty, it is filled with a lot of photons.

Makes me think the folks that are looking at space as an emergent property of matter/energy may be on to something:  http://arxiv.org/abs/1001.0785/

I'm new to this forum, do you have a link to the Lighter-Theory section? Cant seem to find it.
 

Offline Geezer

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Re: empty space at quantum level
« Reply #8 on: 13/07/2012 19:01:49 »


I'm new to this forum, do you have a link to the Lighter-Theory section? Cant seem to find it.


To the left of this window click on "Science Forum" then scroll down through the sub-forums.

Welcome to TNS!
 

Online yor_on

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The big question there is what one mean by 'virtual'.
I like indeterminacy better than 'virtual'.
 

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