Can Photons Really Pop In and Out of Existence?

[Cluelessluke]

I have a question. This question, you should know, is based on something that I actually haven't heard in a classroom or anywhere legitimate, so if the assumption that I have that I'm asking my question about is false, just let me know :)

Alright, the thing I'm assuming is true is that photons can pop in and out of existence. I don't really remember where I heard this, but it was a long time ago and I never really questioned it.

Ok, so my questions is, how?

I came up with my own little explanation for how photons can pop into existence. That is, since the energy of an electron can vary due to the uncertainty principle, an electron could jump form one excited state to a higher energy state without receiving any energy. So then when the electron went to a lower energy state, it would release a photon.

So, I guess I have a few questions now that I actually think about it. Is my basis for this question correct (can photons pop in and out of existence), if they can, is my explanation for how they pop into existence correct (if not, what is the real explanation), and, assuming this is all true, how do photons pop out of existence?

Thanks for your time!

 

[blechman]

This all comes down to "how do we define the vacuum?" The problem is that the vacuum in quantum field theory (the "lowest energy state") is not the state with nothing in it! In fact, photons (and any other particles, for that matter) can be created and destroyed thanks to Heisenberg's uncertainty principle. For an EXTREMELY naive justification for where this energy "comes from", you can think of it as the zero-point energy of the simple harmonic oscillators. Recall that the idea of QFT is to model fields as a continuum of SHO's, each with their zero-point energy. These add up and allow for particles to be created out of nothing, as long as they fall back into the sea. Like a fish jumping out of the water!

Hope that helps.