[bishal123]

I heard according to a law of Einstein it is proved that if human can invent any vechile to run at the spedd of light the human beings shall me immortal. Is it right?? if yes than how??

[Capuchin]

In special relativity, time slows down in an accelerating reference frame. This happens in such a way that someone moving at the speed of light would not experience time. He would travel instantly from his point of view.

A stationary observer would experience time at the normal rate and see him travelling at the speed of light.

So, if someone traveled 1 light year away from Earth and back again at the speed of light, then they would experience the travel instantly, whereas the stationary observer would see the traveler taking 2 years to make their journey.

The traveler would not have aged, but the stationary observer would have aged by 2 years.

This isn't really immortality, as the person moving at the speed of light would have no extra experiences. However it is a way of travelling into the future.

(please note that travelling at the speed of light would require an infinite amount of energy, and is believed to be impossible). However, we might be able to accelerate to a considereable fraction of the speed of light, so we maybe be able to travel a few hundred years into the future at the expense of a few years of our life.