In 2009 the British physicist Stephen Hawking held a party for time travellers – the twist was he sent out the invites a year later (No guests showed up). Time travel is probably impossible. Even if it were possible, Hawking argued that you could never travel back before the moment your time machine was built.
Time travel via speed
The easiest and most practical way to time travel into the far future is to go really fast
- According to Einstein’s theory of special relativity, when you travel at speeds approaching the speed of light, time slows down for you relative to the outside world.
- Using twin atomic clocks, physicists have shown that a flying clock ticks slower because of its speed.
- This is not a conjecture or thought experiment – it’s been measured.
Time travel via wormholes
Many physicists believe wormholes are constantly popping in and out of existence at the quantum scale, far smaller than atoms.
- The trick would be to capture one, and inflate it to human scales – a feat that would require a huge amount of energy but which might just be possible, in theory.
Time travel using light
Another time travel idea put forward by Ron Mallet is to use a rotating cylinder of light to twist spacetime.
- Anything dropped inside the swirling cylinder could theoretically be dragged around in space and in time, in a similar way to how a bubble runs around on top your coffee after you swirl it with a spoon.
Time travel via gravity
According to his theory of general relativity, the stronger the gravity you feel, the slower time moves.
- GPS systems have to account for time dilation effects in order to work. Without these corrections, your GPS capability wouldn’t be able to pinpoint your location on Earth to within even a few kilometres.
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Time travel via suspended animation
Another way to time travel to the future may be to slow your perception of time by slowing down, or stopping, your bodily processes and then restarting them later.
- Some scientists are working towards achieving inducing a short-term hibernation state lasting at least a few hours. This might be just enough time to get a person through a medical emergency, such as a cardiac arrest, before they can reach the hospital.
