At first, I have to point out that only light can travel at the speed of light — mainly because it has zero weight.

Anything with non-zero weight would require exactly an infinite amount of energy to accelerate to the speed of light, because at the speed of light the weight of such a body would be infinite.

That is certainly not possible.

If anyone is wondering what this behaviour results from, the answer is that the special theory of relativity predicts this behaviour.

Although this may seem strange, it is true and we have a lot of experimental evidence for it.

For example, electrons (tiny light particles) are accelerated almost to the speed of light at CERN and each electron thus increases its weight corresponding to the weight of a high-speed train.

If we modify the question a little bit and wonder what would happen to us if we flew at almost the speed of light, then I must say that nothing special.

Just like when we ride a train or fly an airplane — we don’t feel anything special and nothing special happens to our bodies either — this is what Galileo’s principle of relativity describes.

That is, if we always move at the same speed.

But we have to somehow reach almost the speed of light.

The human body can handle an acceleration of 1 g (this is the acceleration given to us by the Earth's gravitational field).

To approach a speed of 300,000,000 m/s (roughly the speed of light) we would have to travel at an acceleration of 1 g for almost a year and in that time we would have travelled a distance equal to 28,000 Earth-Sun distances.

In accelerators, this problem is solved by having the shape of a circle and the particles we study make millions of orbits before we let them collide and observe the results of their collision.