While lawns are mowed cyclically, there is no such thing as a free lawn mowing.Right. If you tried to create matter from a photon, you just end up right back where you started. Paired production that would just annihilate itself again and leave a photon.
I am getting more and more convinced that a cyclical universe would eventually annihilate itself out of existence and just leave a universe of radiation.
I'm getting a little over my head here ... but photons do have particle characteristics, as such should be considered matter ... they also have wave characteristics, as such should be considered energy ...
I don't know ... it's a gauge boson, and is called a "force carrier", which I suppose means they don't carry energy but rather electromagnetic force ... much like a Scotsman's fist is the force carrier, the other Scotsman's face is where the energy is transferred ... and photons only massless at rest, once moving they are affected by gravity which should mean they have mass, thus objects of matter ... just like mowing lawns ...