What is Mass. Article 4. In the big bang, and within the sun, photons and particles convert.
Photons become particle pairs, and particle pairs make photons.
So they both must have very similar and interchangeable properties. A particle is in its own envelope . This envelope is free to roam at any speed and in any direction in our space-time. Using more modern terms the phase velocity would be called a carrier wave. When a snake moves, it curves its back.