Dan Falk is bang on time for our interview. This would not normally be a fact worth noting. He is after all an accomplished and almost certainly a very punctual science writer who is used to making and keeping appointments. However, given the nature of our conversation, it is significant – particularly when he reveals that the time is actually different for him than it is for me.
Falk, the Canadian author of a new book on the philosophy, science, history and psychology of time, sits no more than three feet away from me across a desk. Yet this does not mean that time is running at the same speed for both of us. For as Einstein discovered nearly a century ago, time does not go in a straight line – rather, it is bendy, warped and changes relative to where you are standing in the universe and how fast you are moving. “It seems like you and I are experiencing time in exactly the same way but we are not,” says Falk. “If you and I had a really good atomic clock, they would eventually get out of synch because one of us would be slightly nearer the equator and would be spinning around the earth a little faster – I might also be nearer to a heavy object and subject to its gravitational pull which also affects time.”
Obviously the difference in time between us is so negligible so as not to be observable or even measurable except on the most sensitive equipment – but this is only because we are relatively static and slow moving.
Speed things up a little and things become much more interesting. Falk gives the example of Russian cosmonaut Sergei Krikalev who has spent 800 days in the earth’s orbit – longer than any other human. During this time, because of the speed and distance he travelled around the planet, time effectively shrunk for him, meaning that at the end of his journey he would have been one fiftieth of a second younger than he would have been he had he not left the earth’s atmosphere. Says Falk: “He has effectively travelled one fiftieth of a second into the future. It’s such a small amount that you can dismiss it – it’s not as if your family won’t recognise you. But take the same principle further and the results are more spectacular. I give an example in the book of a man who takes a voyage around the Milky Way galaxy in a space ship which gradually accelerates to a speed close to the speed of light. Obviously the technology to make us go that fast does not yet exist but if it did, his watch would tell him that he completed the journey in 23 years. However, when he returned to earth he would find that 150,000 years had elapsed, so time travel into the future is certainly possible.”
That time, space and gravity are inextricably linked and affect each other is not something which is confined to the realms of science fiction, says Falk. “Global positioning satellite devices [ie. the satnav in your car] communicate back and forth to a network of satellites in orbit. They rely on signals that are coordinated very precisely. Engineers who write the coding for how these signals go back and forth, have to take into account Einstein’s theories of special and general relativity otherwise your GPS would give a result which was off by dozens or perhaps as much as 100 metres.”
Falk accepts that the theory at the heart of Einstein’s theory of general relativity - that matter distorts space and time around it – is hard for people to accept.
In one sense this is the fault of the Jews who were the first civilisation to interpret time as a linear progression. “It does seem to be a Jewish idea, although there is some speculation about whether the Jews borrowed the idea from the Babylonians. The Jews had time mapped out from the creation event, from which time flowed forward, compared to other cultures which have a more cyclical perception of time. The Christian world latched onto the Jewish picture of origins and just added a couple of new chapters to it. There is a strong feeling that this theory paved the way for a scientific world.”
While our world may be predicated on a Newtonian theory of time which has since been proved false by Einstein, our world could not function without it, and we are brought up to rely upon it. So why do we all have the feeling that time flows by in this way when it is demonstrably not doing so. Falk speculates that there was probably an evolutionary advantage in adopting what has been defined as clock and calendar time (CCT). “We imagine time like that. Our parents tell you how to read a clock, how to tell the time. It has been Western civilisation’s most influential ideas – it has seeped in everywhere and there has been absolutely no resistance to its advance.
“People tend to experience time as an arrow [denoting now] moving along a vast imaginary timeline. We are moving at low speed so we don’t experience the extremes of time variation. But is there a ‘now’? A lot of eminent scientists including Oxford professor David Deutscher who I interviewed for this book maintain that it is all subjective. Then, there are African tribes where the past is far more important than the future. There is a tribe in New Guinea whose calendar consists of today, yesterday, the day before yesterday and the day before that. And for them future consists only of tomorrow, the day after tomorrow and the day after that. So they live in a perpetual Wednesday.
“While we might share the same clock, people in other parts of the world have a very different attitude towards it. If you show up an hour late for a meeting in Brazil, it’s not a big deal but if you’re 10 minutes late in New York or London you would be expected to explain why. In Tokyo, that margin is 90 seconds.”
Of course all of this is very interesting but we cannot have an interview about time without asking the all-important question. Is there any way that I can travel back to 1967 and place a bet on Foinavon to win the Grand National at 100 to 1. Falk, looking wonderfully geeky in shorts and backpack, does not dismiss backwards time travel but says there are problems – not least of which the grandfather paradox. Should you manage to go back to say, 1930 and accidentally run over your grandfather before he married your grandmother, then how could you exist? Would the laws of physics somehow make it impossible to do away with him? Or are there, as some assert, parallel universes?
“There are lines of evidence which could indicate parallel universes – there is also, in theory at least, a way to travel into the past – through wormholes, a kind of double ended black hole which could act as a bridge through space and time. But there are still lots of questions. What would happen if a billiard ball went through a wormhole, came out the other end and struck itself, thus preventing it going through the wormhole. And what happens if you travelled back in time to Downing Street five years ago? The security video cameras would have recorded you, so you would be able to check the tapes now to see if you got there. And if the tape shows you there then you have to do it. Every blink of your eye, arm and leg movement has to be as it is on the tape. So what does that say about free will?”
Falk leaves me with that thought. He clutches his backpack, shakes my hand and leaves … either slightly before or slightly after I perceive him to be doing so.
In Search of Time is published by the National Maritime Museum at £14.99