Can we Send Humans into the Distant Future?
‘The universe is not only queerer than we think, it is queerer than we CAN think’ – J.B.S Haldane
A hundred years ago, the idea of humans travelling through space seemed outrageous to most. Space travel, like time travel, was merely science fiction. Today, spaceflight is commonplace. Might time travel one day become commonplace too1?
Travelling through time is certainly easy to imagine. You step into the time machine; press a few buttons; and emerge out not just anywhere – but anywhen. However, in reality things aren’t quite as convenient as science fiction would suggest, as you will understand later on.
At a glance, the concept of time travel seems absurd. Yet given some thought, you realise the metaphorical wall between the past, present, and future is smaller than you think. Light travels at a constant velocity of about 300,000 km/s. It is common knowledge that nothing can travel faster than that speed (as I will prove later on) and therefore because your eyes are sensitive to visible light – everything you see is a light wave in some form. Because of this finite velocity of light, if we observe a star, say Alpha Centauri 4 – which is 4 light years away – we do not see it as it looks today, but as it looked 4 years ago! If you look at the Andromeda Galaxy – 2 million light years away – you see it as it appeared 2 million years ago. Just as when you look at yourself in a mirror – 1.5 metres away – the image you see of yourself is not you now, but you 10 nanoseconds ago (0.00000001s)2. In other words, you look into the past every moment of your life.
In addition, technically speaking we are all time travellers into the future. We move at a rate of 1 second at a time into the future – it probably is not your idea of time travel; it certainly is not mine!
I deem it important that if you are to successfully understand the seemingly absurd concepts behind the study of time travel, one must first understand and appreciate the very nature of space and time, and for that matter – space-time.
Firstly time. Whatever you have read or heard, nobody understands what time really is3, however I can describe it. The great physicists of old – Newton, Galileo, Aristotle, Maxwell – as great as they were, all failed to comprehend the true nature of time. They assumed space and time were separate. There was space, a field where one could traverse freely, given coordinates and a velocity – and time, a fixed constant, flowing irrespective of everything else, absolute and universal everywhere. ‘Absolute, true and mathematical time, flowing equably without relation to anything external’ was the way Isaac Newton expressed it. And this ‘Newtonian’ mechanistic view of time was the accepted notion for over 200 years.
It took the phenomenal insight of Albert Einstein in 1905 to publish his works of Special Relativity and in 1916 when he published his generalised theory. The theory of relativity was the birthplace of modern...