If someone were to pass you at 90% the speed of light, what would happen?

For someone moving at speeds closer to the speed of light, the universe will seem moving in slow motion around it, while those who watch that person from outside will watch it in slow motion.

This is because according to Einstein's theory of relativity, a person who is still and another who travels at a speed very close to the speed of light should see a ray of light move at the same speed (because the speed of light is constant) and that is only possible if the two persons experience time differently.

Another thing that would happen is that the field of vision of the person traveling at 90% of speed of light  would change, the world would appear through a tunnel-shaped window, due to the length contraction.

scientific laws are the result of testing theories and proving them to be facts.