The recent measurements of the Casimir effect by Wilson, et al established the existence of a pervasive background of charged particles in what has been perceived as an empty Universe. As a result, photons moving through what has hitherto been taken as a vacuum will be slowed, while neutrino speed will be unaffected. All our measurements of the propagation of light and its wavelength have not been corrected for this slowing.
Wilson's result means the very idea of a vacuum is revealed as an unattainable limit. Now we must regard c as a value that is the limit of velocity in our Universe in its role as a dimensional coefficient in the Minkowski metric, similar to absolute zero in the temperature domain. The SI system has referred to it as c0 and so shall we.
If this insight is correct relativistic limits still hold and the space/time index of refraction is slightly greater then 1. The actual measured speed of light is slowed by space/time and is a measure of the consistency of space/time.
Until the refractive effects of the background particles are either measured or calculated, we really can not assert any violation of relativistic limits. To the latter end, we will soon propose some experiments which might accomplish such measurements.
I submitted this insight to Nature in December of 2011 as a comment on the Casimir effect experimental results. Now a group of French physicists have come to a related conclusion and just announced their results and intentions.
Note 3/26/13 Urban et al. has made some estimates of light speed and we look forward to their experimental results to confirm their and our expectation of photon interaction of quantum foam.
This is indeed a very interesting result, although currently there is no definitive theoretical explanation of the variation of c in vacuum: http://www.csmonitor.com/Science/2013/0325/Scientists-examine-nothing-find-something
I'm merely a retired information systems analyst, but there certainly may be a theoretical explanation for the variation of c within a superconducting field. As I understand, photons have been observed to exhibit the characteristics of rest mass within a superconducting field.
It does not seem appropriate to simply extrapolate experimental results obtained in such extreme conditions to the prevailing conditions of the cosmological vacuum...
The velocity of light naturally depends on the medium, but the new (thought) experiment addresses the fundamental issue of velocity of light in vacuum, i.e. without any medium that interacts with the photons. That this fluctuates is a new result, which has not been observed yet. A plausible explanation is the influence of spontaneous vacuum fluctuations, but exactly how this works is still speculative.
As I understand, the Casimir effect is thought to be the a product of virtual particle interactions. If their manifestation rate or density is increased by the presence of a superconducting magnetic field, then the experimental results were not obtained in a true vacuum, but a dense medium of virtual particles.
This possibility strongly suggests that the varying c results should not be immediately applied to the cosmological vacuum, unless the cosmological vacuum includes the the universal influence of a superconducting magnetic field.
Am I misunderstanding something?
http://en.wikipedia.org/wiki/Speed_of_light#Astronomical_measurements indicates that the speed of light has been experimentally determined within the Solar system, which is of course not a perfect vacuum, but there is no evidence for any significant delay due to even spontaneous vacuum fluctuations.
Meanwhile the problem statement begins with what seems to me to be a false assertion:
"The recent measurements of the Casimir effect by Wilson, et al established the existence of a pervasive background of charged particles in what has been perceived as an empty Universe."
Unless I misunderstand, the Wilson, et al study only determines that spontaneous vacuum fluctuations can occur in very specific laboratory conditions influenced by a superconducting EM field. Those peculiar results cannot be extended to the vacuum of intergalactic space, for example, unless there is evidence for superconducting EM fields permeating intergalactic space, correct?
I these statements are not correct, please explain.
James, you're right that the first sentence in the Question here makes no sense. It has been known for decades that the vacuum spontaneously fluctuates. This is standard in every graduate level textbook in relativistic quantum mechanics.
What I don't understand is why you bring "superconductivity" into the issue of light velocity in space/vacuum. This is irrelevant. Traditional superconductivity is the spontaneous pairing of fermions into composite bosons. What matters for light are the spontaneous quantum quasiparticle fluctuations.
Tapio,
There was no specific publication cited for the Wilson et al. research - I found:
Wilson, et al., (2011), "Observation of the Dynamical Casimir Effect in a Superconducting Circuit," http://arxiv.org/abs/1105.4714
If this is the research report mentioned, then superconductivity certainly is relevant, and it's not correct to state:
"The recent measurements of the Casimir effect by Wilson, et al established the existence of a pervasive background of charged particles in what has been perceived as an empty Universe."
The recent measurements I found applied only to the quantum foam within a superconducting circuit. It's known that the range of EM effects become much shorter within a superconducting field, including the propagation of light, which exhibits characterisitics suggestive of a non-zero rest mass. I think the basic premise here that the measurements of virtual particle manifestations within a superconducting circuit can be extended to cosmological spacetime is invalid.
I realize that vacuum fluctuations must occur in intergalactic spacetime, the questions is whether transient virtual particles interact with intergalactic light emissions sufficiently to affect their propagation speed. I do think the Wilson et al. results are very interesting, but I'm pretty certain that their measurements within a superconducting circuit cannot be applied to universal spacetime.
James, I'm sorry but I repeat that you seem to have some kind of fundamental misunderstanding here. First, the Nature paper of Wilson et al. is just a confirmation of an old idea that the well-known Casimir effect can be used to convert virtual photons into real ones (this is the so-called dynamical Casimir effect). A superconducting SQUID is just used as a tool to facilitate this trick.
The new paper by Urban et al. theoretically proposes (does *not* measure) that the measured speed of light may be determined by the quantum fluctuations of fermions in vacuum and thus it's only an average value, which fluctuates. This is a tiny effect and I'm not qualified to judge whether or not it could be actually measured.
Tapio,
Respectfully, I don't think I'm misunderstanding anything. I think your misunderstanding results from your not having read the question posted.
My comments are in regard to the assertions made in the question posted, referring to the work of "Wilson, et al". Since they all seem to be invalid, I have not read and do not intend to read the Urban et al proposal. I'm dismissing the question as invalid.
Since it seems you have not read it, I repeat the question posted: please read carefully:
Q. "Quantum Foam requires the reassessment of the Speed of Light"
"The recent measurements of the Casimir effect by Wilson, et al established the existence of a pervasive background of charged particles in what has been perceived as an empty Universe. As a result, photons moving through what has hitherto been taken as a vacuum will be slowed, while neutrino speed will be unaffected. All our measurements of the propagation of light and its wavelength have not been corrected for this slowing.
"Wilson's result means the very idea of a vacuum is revealed as an unattainable limit. Now we must regard c as a value that is the limit of velocity in our Universe in its role as a dimensional coefficient in the Minkowski metric, similar to absolute zero in the temperature domain. The SI system has referred to it as c0 and so shall we.
"If this insight is correct relativistic limits still hold and the space/time index of refraction is slightly greater then 1. The actual measured speed of light is slowed by space/time and is a measure of the consistency of space/time.
"Until the refractive effects of the background particles are either measured or calculated, we really can not assert any violation of relativistic limits. To the latter end, we will soon propose some experiments which might accomplish such measurements.
"I submitted this insight to Nature in December of 2011 as a comment on the Casimir effect experimental results. Now a group of French physicists have come to a related conclusion and just announced their results and intentions.
"Note 3/26/13 Urban et al. has made some estimates of light speed and we look forward to their experimental results to confirm their and our expectation of photon interaction of quantum foam..."
In the past I did some research about Quantum Foam. I focussed my attention on black holes, Zero Point Energy (the Casimir Energy if You prefer!!), and the Cosmological Constant. Actually I never tried to study the interaction between phtons and the foam, but my personal opinion is that if You believe in VSL (varying speed of light) models of cosmologies, such an interaction should modify the usual behavior of the light. There is also a paper of Klinkhamer appeared in PRD 2004 about this subject. Here it is the complete Ref.
Phys. Rev. D 70, 045020 (2004) [14 pages]
Spacetime foam, CPT anomaly, and photon propagation
I hope this could be of help for You
Again, this 'question' posting declares that there is a (new) requirement to test the speed of light, claiming:
"The recent measurements of the Casimir effect by Wilson, et al established the existence of a pervasive background of charged particles in what has been perceived as an empty Universe. As a result, photons moving through what has hitherto been taken as a vacuum will be slowed, while neutrino speed will be unaffected. All our measurements of the propagation of light and its wavelength have not been corrected for this slowing."
In fact the Wilson et al study I found establishes only that photons are slowed within a superconducting circuit. It has previously been shown the EM field effects become localized in the presence of a superconducting field. I can only conclude that these results do not apply in the absence of a superconducting circuit, ad thus cannot be universally extended to all vacuum conditions.
Please see
Wilson, et al., (2011), "Observation of the Dynamical Casimir Effect in a Superconducting Circuit," http://arxiv.org/abs/1105.4714
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