Science Fact: Scientists say building a time machine may be extremely difficult. But time travel is not against the laws of physics!
For thousands of years, scientists and philosophers have talked of time as a river that flows steadily onward year after year. But what if there were a way to swim against the flow, or to run down the bank ahead of the river? Might we be able to journey back and forth in time just as we travel through space? The idea is not as far-fetched as it sounds, and the implications for the future are intriguing.
Ever since Einstein, scientists have considered three-dimensional space and time not as two different things, but as different aspects of four-dimensional "space-time." Quantum physicists, who study the world of subatomic particles, often find it easier to explain events by assuming time runs backward as well as forward, however much it defies common sense. At the other extreme, cosmologists looking at the universe on a grand scale have found that space and time can be warped by gravity and speed. Back in the 1940s, German mathematician Kurt Goedel proved that if we could warp and twist space-time enough – creating what he called "closed, timelike curves" – then we could bore tunnels through time itself. But no one knew how to do the twisting – until black holes. The gravitational pull of a black hole is so enormous that it distorts the very fabric of space-time into what is called a singularity. When singularities were found to spin, it was proved that closed, timelike curves not only can occur – they must occur. The singularity forms a doughnut shape in space-time, while the hole in the middle is a perilous gateway to somewhere – or when.
On the following pages we'll show you some ways it may be possible to travel in time without breaking the rules