At this precise moment we are hurtling through time at a speed of one second per second.

Scientists do believe that it is possible to build a time machine to visit the future.

In 1971, two physicists, Joe Hafele and Richard Keating put highly accurate atomic clocks into aeroplanes and flew them around the world, and compared their readings with identical clocks left on the ground.

The results proved that time ran more slowly in the aeroplane than on the ground. The clocks in the aeroplanes were 59 nanoseconds slower than the clocks on the ground, as predicted by Einstein (see "Relativity" topic page).

The closer to lightspeed you travel, the slower time passes.

Light travels at a speed of 299,792.458km per second.

In a year, light travels

9.46,000,000,000,000km. (One light year.)

The slowing of time is known as the "time dilation effect". Which was coined by Einstein. Think of a speed, divide by the speed of light, square it, subtract from 1. Take the square root, and the answer is Einstein's time dilation formula.

At half the speed of light, time is about 13% slowed, at 99% it's 7 times slower and, -1 minute is reduced to about 8.5 seconds.

This timewarp becomes infinite when the speed of light is reached.

Unfortunately, the light barrier can never be breached. Nothing can travel faster.

The nearest star to our Sun, Proxima Centauri, is 4.2 light years away. Which means it takes light 4.2 light years to reach us.

Our Galaxy, the Milky Way, is 100,000 light years across.

Because time is stretched by speed, for the astronauts insided of a spaceship travelling at 99% of the speed of light across the Galaxy would be completed in just 14,000 years.

At 99.99% of the speed of light, the trip would last just 1,400 years. If you could reach 99.999999% of the speed of light the trip could be completed in a human lifetime.

At present, our spaceships can only muster a speed of 0.01% of the speed of light.

At the particle accelerator in CERN Laboratory near Geneva, electrons are being propelled at speeds of 99.999999999% of the speed of light.

If you got caught up in the gravitational field of a black hole, and just so happened to be spinning in a rotating cylinder at speed, it is possible that you could be moving faster than light itself and thus, arrive before you left.

To outpace light, we would need a wormhole (see "Wormholes" topic page). Which, if you managed to pass through one and travel through time, the "grandfather paradox" could occur. The grandfather paradox is similar to the twins paradox (see "Relativity" topic page), imagine travelling back in time, killing your own grandfather.

So, there may be time travellers among us. Who's to say otherwise?