The problem of light speed, welcome to discuss in the near future! ! !

It is 100% of the speed of light. Hexie3605' s answer is actually quite good, but there are some mistakes to be pointed out, that is, the time of a person moving at 80% of the speed of light does not slow down in the reference system, while the person in the static reference system only slows down the measurement of that person's inherent time. In fact, this question doesn't need any coordinate transformation to answer, because for the theory of love relativity, an important premise is the principle that the speed of light is constant, that is, the speed of light is the same in any reference frame, so the speed of light of the person who moves at 80% speed of light in the reference frame must be 100% speed of light, and he is still in his reference frame! But if you look at the ground reference system, light will surpass that person at the speed of 20%, but these are not contradictory, because it is normal that two different reference systems cannot reach the same conclusion.

In addition, it should be pointed out that the theory of relativity of love only applies to the case that the speed of light is less than the speed of light, because according to the theory of relativity of love, the speed of light is the limit speed, and no speed can reach the speed of light. Because the mass of an object increases with the increase of the speed of motion, it becomes more and more difficult to accelerate the object, and finally the speed of the object cannot reach the speed of light. All physical phenomena (if possible) in which the speed of an object reaches or even exceeds the speed of light cannot be explained by the theory of relativity of love, because the theory of relativity cannot be applied in that field. If you want to discuss the situation here, you should need a new theory to explain it ~