Trying to reach the speed of light, or at least trying to get anywhere near it, has always presented an interesting challenge to space travel in science fiction. Currently we are far from being able to reach such high speeds, but is it possible to try to reach such high numbers? And why should humanity try? For a body with mass, reaching the speed of light (c) is impossible. Reaching this speed would be extremely useful for several reasons, especially to get to explore planets billions of kilometers away from the Earth, but the speed "c" remains an insurmountable and unattainable limit for any body with mass. In fact, to reach the speed of light would require infinite energy.
The equations of relativity: E=mc²
Einstein's famous equation, E=mc², states that there is a link between mass and energy and that one can transform into the other and vice versa. When a body is accelerated, the energy goes to increase the mass. As we approach the speed of light, it will take more and more energy to increase the speed of the body until, to try to reach "c" it would be necessary to offer an energy equal to infinity, but we know that this is not possible in reality.
The tachyons.
So under no circumstances could the speed of light be exceeded? In fact, a body of imaginary mass (i) could do it.
Why imaginary mass (i)?
The relativistic energy formula tells us that the energy E is E=(mc²)/√[(1-(v²/c²)].
If the speed of light were exceeded, we would get a negative denominator under a square root. We get so an imaginary number in the denominator. At this point, the energy would also be an imaginary number, but to solve this problem one could consider the mass of the particle an imaginary number. This way, "E" would be a real number and not an imaginary number .
These particles have been called "Tachyons" but we don't know if they actually exist, at the moment there is no reason to think that they can actually exist. Why? The main reason is about time travel. In fact, exceeding the speed of light, one would travel back in time. For this reason, either tachyons could be used to send information into the past, but this could create time paradoxes for which a trip back in time would be impossible, even if some scientists have tried to give a solution to these paradoxes, opening a small glimmer of hope towards journeys into the past. At the moment, however, we are still in the realm of science fiction.
