Is it possible in principle for a human being who has a life expectancy of 70 years to make a round-trip journey to a part of the universe thousands of light-years distant? Explain.
According to theory of relativity the ship moves in speed of light causing time dilation,which make time on spacecraft is slower compared to move slower on earth.their age will be number of minutes take to trip.when they get back the time on earth will have passed one year for every light year traveled. Or You can also slow your age and effectively travel forward in time by travelling at high speed.time dilation is would be measured by a clock would have the same effect on the physical process in your body that cause age. Suppose you travel away from earth at near light speed,then turn around and come back.someone stays on earth,your time is slow during your trip,so when you return.they expect you will have aged less than they have.this is because of symmetric nature of time dilation caused by constant relative velocity. :