question on photons popping in and out of existence

[wyef]

does light (photons etc.) pop out of existence, then return, at the same location and still travelling in the same direction? I note articles saying photons do pop into existence enough to be visible, tho no mention of duration of the light.

[ACG52]

Not unless they run into electrons.

[Enthalpy]

The first message's claim is doubtful. We know that a photon has existed when it is destroyed, and at no other time - except maybe in some very subtle recent experiments. So what is meant by "pop out then return" and by "duration of light"?

[swansont]

Are you asking about vacuum fluctuations?

[wyef]

The first message's claim is doubtful. We know that a photon has existed when it is destroyed, and at no other time - except maybe in some very subtle recent experiments. So what is meant by "pop out then return" and by "duration of light"?

probably should have said direction rather than duration. I was attempting to ask the direction of the light observed in recent articles on experiments. Apparently in a vacuum photons pop into existence, and photons pop out of existence. In the recent articles the photons existed long enough to detect as visible light (possibly only to equipment, article not specific on what was meant by visible). I may be making an incorrect assumption that some existing photons also pop out of existence. Curious on whether light travelling in a direction through space loses some photons via this effect, and then do the photons return.

[swansont]

The photons that pop into and out of existence are virtual photons, and we generally can't directly detect them. One exception is if you can add energy to them and make them real photons, which can be done in the dynamical Casimir effect.

 

http://www.technologyreview.com/view/424111/first-observation-of-the-dynamical-casimir-effect/

[wyef]

Are you asking about vacuum fluctuations?

yes, as I understand it, or more correctly do not understand it, One of the links I read, talks about making part of the light (or photons) pop out, then changing the relationship it had with others using mirrors, thus preventing its link or relationship. The result then appears to be the mirror reflects a light that is no longer there, making it appear to come directly from the mirror. I was interested in the direction of the light compared with the origional source. I note its not a real mirror, but some type of virtual mirror, but the light was supposedly real.

[swansont]

That almost sounds like the Casimir effect, though in that case the mirrors are real and the photons are not.

[wyef]

That almost sounds like the Casimir effect, though in that case the mirrors are real and the photons are not.

Trying to find the article again, but found many referring to the study by a man named wilson. I am new to this forum and do not know how to paste in a url address, but nature.com was one of the sources.

In the study a "virtual" mirror was vibrated to simulate mirrors, and yes it is the casimir effect. Apparently after stopping light (or photons) came out of the mirror after the fact. I note there is speculation articles on todays search that seem to claim this study indicates our grasp of the speed of light in vacuum is wrong or off slightly. My question may be unanswerable at this time, but each of the articles I have read indicate that the photons return is visible or detectable depending on the writer, which prompted me to ask if it resumes its direction.

A second related question would be if any natural photons or light do this during the lights travel over a large distance.

[swansont]

Trying to find the article again, but found many referring to the study by a man named wilson. I am new to this forum and do not know how to paste in a url address, but nature.com was one of the sources.

In the study a "virtual" mirror was vibrated to simulate mirrors, and yes it is the casimir effect. Apparently after stopping light (or photons) came out of the mirror after the fact. I note there is speculation articles on todays search that seem to claim this study indicates our grasp of the speed of light in vacuum is wrong or off slightly. My question may be unanswerable at this time, but each of the articles I have read indicate that the photons return is visible or detectable depending on the writer, which prompted me to ask if it resumes its direction.

A second related question would be if any natural photons or light do this during the lights travel over a large distance.

 

Yes, that's the dynamical Casimir effect, to which I linked in an earlier post (you can simply copy/paste the url to do this, BTW). The energy to create the real photons comes from the oscillating device.

[EdEarl]

I read wikipedia about virtual particles, which confused me.

Virtual particles do not necessarily carry the same mass as the corresponding real particle, although they always conserve energy and momentum. The longer the virtual particle exists, the closer its characteristics come to those of ordinary particles.

From: http://en.wikipedia.org/wiki/Virtual_particle

However, all particles have a finite lifetime, as they are created and eventually destroyed by some processes. As such, there is no absolute distinction between "real" and "virtual" particles. In practice, the lifetime of "ordinary" particles is far longer than the lifetime of the virtual particles that contribute to processes in particle physics, and as such the distinction is useful to make.

From: http://en.wikipedia.org/wiki/Virtual_photon#Actual_and_virtual_particles_compared

 

The quote seems to say that particles (both virtual and real since there is "no absolute distinction") change mass depending on the length of time they exist.

 

The article uses a virtual electron as an example particle, but I searched for virtual photon; thus, the article is apparently discussing all particles including photons. If so, I assume the word mass means mass-energy.

 

I learned that less energetic photons have longer wavelengths. Does that mean that a virtual photon changes wavelength the longer it exists?

 

A virtual electron is created with a virtual antielectron. Two virtual photons are created, is there a difference between them that makes the pair annihilate, or do they just simultaneously "fade" into the vacuum energy.

[wyef]

Yes, that's the dynamical Casimir effect, to which I linked in an earlier post (you can simply copy/paste the url to do this, BTW). The energy to create the real photons comes from the oscillating device.

Thanks, do the photons observed at the close of the experiment maintain their orignal direction? Or, is that unknown at this time?

It appeared to me reading the articles that this would indicate a delay in the path of the light/photon.

[swansont]

Thanks, do the photons observed at the close of the experiment maintain their orignal direction? Or, is that unknown at this time?

It appeared to me reading the articles that this would indicate a delay in the path of the light/photon.

 

There is no "original direction". These are not photons that disappeared and then reappeared. These are photons created by the interaction of the mirror with the vacuum.

[Sharapovaphan]

The emission would have to be a "virtual photon" otherwise it would violate E = MC^... Also, predicting the angular direction of a specific photon emitted isn't possible. I don't think.