Does light have mass? According to most scientists, light has no mass. But that's a big problem to say, because science doesn't know what mass really is.
So, how can you say that something has no mass if you don't know what mass is? Science assumes that if light had mass, because of its speed, its mass would be infinite. For every object that arrives at the speed of light would have infinite mass.
The big problem is, is the speed of light really the greatest speed?
If light is in a material medium, its speed is reduced. For example, the speed of light in water is 25% slower than the speed of light in vacuum. So in that case could light have mass?
See if you don't know what mass is, you can't define that light has no mass.
Let's, for example, do a hypothetical experiment. Assume a very strong light source, directed towards a black hole. A black hole has gravity because it has mass, and light is affected by gravity, but they say it has no mass.
But light has energy. Einstein's formula is that Energy is mass times the speed of light squared. But light has no mass, so scientists define light as having momentum.
So, let's say a lot of light is thrown into a black hole, does the black hole's gravity increase, or does it not increase?
It increases, because the light that has no mass has turned into mass in the black hole. And if the black hole didn't increase gravity, where did the light energy thrown at the black hole go?
Thus, it is irrational to define light as massless, or to create a new rule in which momentum and mass exchange existence.
Science currently needs to have more rational definitions, than to create at all times a concept that is extremely out of reality, and even out of physical laws. Like multiverses, dark matter, dark energy, infinite density, and many other things.
