What happens when two photons collide?

[imatfaal]

There are bunch of articles on this and supposedly experiments to back it up. So it seems that two gamma ray photons can be converted into an electron-positron pair in a vacuum. Perhaps the probability deceases with photon energy? For example, an electron neutrino with less than 0.0000022 MeV/c^2, which is about the energy of a visible green photon of 564 nm. Will any electron neutrino & anti electron neutrino pair be created by two crossing perpendicular beams of 564 nm photons?

 

I have not seen a write-up of a simple gamma-gamma interaction using two beams of light - most of the experiments involve very high speed charged particles and the photons they emit under rapid acceleration (when in close approach with anti-particle)into each other such that an incredibly high energy gamma photon is produced. You note the electron / positron which has emitted the v-hi energy photon as it is deflected - and you note a decay cascade of hadrons which only make sense for a photon photon collision

[Theoretical]

I have not seen a write-up of a simple gamma-gamma interaction using two beams of light - most of the experiments involve very high speed charged particles and the photons they emit under rapid acceleration (when in close approach with anti-particle)into each other such that an incredibly high energy gamma photon is produced. You note the electron / positron which has emitted the v-hi energy photon as it is deflected - and you note a decay cascade of hadrons which only make sense for a photon photon collision

Here's a photon-photon experiment. The final step consists of a photon-photon interaction to create matter.

 

http://www.nytimes.com/1997/09/16/science/scientists-use-light-to-create-particles.html

 

Wikipedia has this interesting statement, "From quantum electrodynamics it can be found that photons cannot couple directly to each other, since they carry no charge, but they can interact through higher-order processes. A photon can, within the bounds of the uncertainty principle, fluctuate into a charged fermionantifermion pair, to either of which the other photon can couple. This fermion pair can be leptons or quarks. Thus, two-photon physics experiments can be used as ways to study the photon structure, or what is "inside" the photon."

http://en.m.wikipedia.org/wiki/Two-photon_physics

[ajb]

Thus, two-photon physics experiments can be used as ways to study the photon structure, or what is "inside" the photon."

I would be careful putting it like that. The photon has no internal structure, or at least as far as we know. It is a fundamental particle that is associated with the electromagnetic force. There is 'noting inside' as such. The point is that photons carry energy and you can if there is enough energy under the right conditions create matter antimatter pairs. These pairs were never really inside the photon. I think you know this as you use "_____", however just to be clear I thought I would comment.

[swansont]

I would be careful putting it like that. The photon has no internal structure, or at least as far as we know. It is a fundamental particle that is associated with the electromagnetic force. There is 'noting inside' as such. The point is that photons carry energy and you can if there is enough energy under the right conditions create matter antimatter pairs. These pairs were never really inside the photon. I think you know this as you use "_____", however just to be clear I thought I would comment.

 

That's directly from the wikipedia page. When one clicks the link to photon structure, there is a note that "this page has some issues"

[ajb]

That's directly from the wikipedia page. When one clicks the link to photon structure, there is a note that "this page has some issues"

Okay, thanks.

[Theoretical]

 

That's directly from the wikipedia page. When one clicks the link to photon structure, there is a note that "this page has some issues"

I see that in the photon structure page like you said while in mobile mode. In the desktop mode it only says this article may be too long. Do you see errors in the page? BTW the Two-photon physics page doesn't have the issues notice.

[swansont]

Do you see errors in the page? BTW the Two-photon physics page doesn't have the issues notice.

 

I don't, but it's far enough outside my wheelhouse that they would have to be large errors in order for me to spot them.

[imatfaal]

I see that in the photon structure page like you said while in mobile mode. In the desktop mode it only says this article may be too long. Do you see errors in the page? BTW the Two-photon physics page doesn't have the issues notice.

 

But the two-photon page manages not to mention the very interesting experiments that you quoted above - it seems that this section of the wiki is a little neglected