Can Matter be Created or Destroyed?

[Alex K]

I've read that the device used to produce particle pairs is called a particle collider. this is a type of particle accelerator. You need at least 2 photons that do something in the vicinity of a heavy atomic nucleus, such as  lead or gold.

What I'm trying to find is exactly what the photons do in the process of conversion to an electron-positron pair, and what is their relationship to the nucleus. Do they collide with the nucleus or with each other?

Yes, pair creation happens all the time at colliders such as the Large Hadron Collider (you do know my LHC thread, right?

http://atheistforums.org/thread-33518.html
)
If you want to know what photons do in pair creation, it is useful to look at the corresponding feynman graphs.



Basically, according to current understanding, the photons exchange a virtual electron and this results in an electron and a positron to be created. Quantum electrodynamics simply postulates the interactions between the electron/positron and photon fields, no deeper underlying mechanism of interaction between them is known. In superstring theory, which is speculative, various models give a more detailed account how the conversion happens - such as end points of strings changing from one higher dimensional "brane" to another and thus changing the particle type.

Anyways, the nucleus in such experiments usually merely provides a counter mass which can absorb/emit a photon for the process. The precise details of the nucleus are usually unimportant, what you need is some massive thing with an electric charge.