# Can anything be faster than light?

Jaroslav Kores, Ph.D.

It can but it won’t do us any good. I will not deal with hypothetical particles (tachyons), which in my opinion are more of a mathematical game resulting from the Theory of Relativity.

It follows from the Theory of Relativity that when speed increases, the mass of the body also increases. The faster the object moves, the greater is its mass. This phenomenon is experimentally proven but it only occurs noticeably at speeds approaching the speed of light. Any mass particle would have infinite mass when it reached the speed of light (which would require an infinite amount of energy to accelerate it to the speed of light). That will never happen. The only particles that move directly at the speed of light are photons, i.e. particles of light itself. They can move at the speed of light only because their rest mass is zero. All this is described by Lorentz transformations, in which for velocities higher than the speed of light, the square root of a negative number results (therefore it has an imaginary solution, which precisely, are tachyons), for the speed of light it results in division by zero (i.e. infinity for particles with non-zero rest mass and then a mathematically funny result of 0/0 for photons).

Another limitation follows from the theory of relativity — causality, which we can simply interpret as information cannot move faster than light.

But it is quite simply possible to achieve a speed greater than the speed of light — for example with a laser aimed at the Moon. If we moved a powerful laser on the ground at a speed of 1 m/s in a circular path with a radius of 1 m (that is, I am holding a laser pointer in my hand and rotating it at a speed of 1 m/s), the laser dot on the moon would move faster than light. But this in no way conflicts with the above mentioned limits from the Theory of Relativity — the laser point has no mass and I also transfer no information this way. If I wanted to transfer some information, I would have to, for example, turn the laser on and off (type out Morse code). But this tapping would travel to the moon at the speed of light (using an intermittent laser beam).