According to our current understanding of physics, particles with mass cannot travel faster than the speed of light in a vacuum. This is a fundamental principle of special relativity, which is a well-tested and widely accepted theory.
If there were particles that could travel faster than light, it would have significant implications for our understanding of the universe. One consequence would be the violation of causality, as information and signals could be transmitted faster than the speed of light, leading to paradoxes and inconsistencies.
As for the size of the universe, our understanding is based on the observations and measurements we have made so far. The observable universe is thought to have a finite size, estimated to be about 93 billion light-years in diameter. This is the distance that light, traveling at the maximum speed, could have traveled since the Big Bang.
If particles were able to travel faster than light, it could potentially change our understanding of the universe's size and structure. However, it is important to note that no experimental evidence or observations have confirmed the existence of particles traveling faster than light. The current consensus among physicists is that the speed of light in a vacuum is an absolute limit.