In physical realism, movement is a natural property of matter so there is no reason why it can’t just go faster and faster but special relativity is clear that matter can never reach the speed of light. Physical realism has no explanation at all for the universal speed limit that relativity describes.
In quantum realism, light is a constantly spreading wave of quantum processing and matter is the same processing as a standing wave that constantly restarts. This explains why light inherently moves but matter is inherently stationary but raises the unexpected question: If matter is a standing quantum wave, how does it move at all? Quantum theory suggests that it is because matter trembles.
QR5.3.1. How Matter Moves
QR5.3.2. How Matter Changes Space and Time
QR5.3.3. Kinetic Energy And Photons
QR5.3.4. Bit-shifting Reality