The universe has no boundary, no beginning. Self-existed indestructible charged particles form into atoms under the electrostatic attraction and repulsion force they carry. Atoms attract atoms to form into matters under the gravity/net electrostatic attraction and repulsion force of all charged particles in all atoms.

The more matters attracted together, the more mass carries the stronger gravity, the higher the energy density, and the higher temperature it has, its atoms oscillate faster, carry higher-frequency alternating current. 

Line of sight matters repel each other with universal repulsion force/levity, therefore their surface electrons oscillate simultaneously at any distance. Therefore radiation/light speed is infinity in vacuum space.