Is Time Travel Possible?
Travelling forwards in time _____77_____ surprisingly easy. Einstein’s special theory _____78_____ relativity, developed in 1905, shows that time _____79_____ at different rates for people who are moving relative to one another - although the effect only becomes large when you get _____80_____ to the speed of light. If one were to leave Earth in a spacecraft travelling at an appreciable fraction of light speed, turn around and come back, only a few years might have passed on board but _____81_____ years could have gone by on Earth. This is known as the “twin’s paradox”, since a traveller undertaking such a journey would return to find herself much _____82_____ than her twin. There’s only one problem from anyone wishing to get a glimpse of the future – getting back. It would mean travelling faster than light – and that’s not possible.