Having had numerous lectures on Relativity and Cosmology, Wycombe Astronomical Society members are well familiar with the concept of space-time. But Colin Stuart challenged us to think a little harder about the time element of this – and the implications for us as to whether we have any control over our destiny.
Consider the Grandfather Paradox, for example. Suppose you could travel back in time to when your grandfather was in his infancy, with the intention of murdering him so he could not go on to become the person he became. No matter what you did, you could not kill him – you would be destined to fail (obviously because your grandfather enabled one of your parents to be born, and hence they gave cause for you to be born). Basically, your future is pre-determined – you have no control.
Then Einstein revolutionised our concept of time – time doesn’t work like this. His theory of Relativity showed that time and space were inextricably linked – two sides of one coin if you like. And out of it emerged our concepts of how the universe worked. For example, how gravity works. We perceive gravity as a force, pulling objects of mass together. Einstein envisioned space-time being distorted by large masses, causing objects near large masses to fall in towards the large mass. And as things move through space-time, they cause waves – gravity waves.
So where does tomorrow come from and where did yesterday go? Well, the Bing Bang created all space- time – one cannot add or subtract any. Accordingly, tomorrow doesn’t go away – the entirety of the past, present and future all coexist. In the view of Einstein, just as we perceive gravity wrongly, “the distinction between the past, present and the future is only a stubbornly persistent illusion”. Time, in other words is an illusion.
Something else Einstein realized was that, regardless of its being an illusion, time runs at different rates depending on one’s speed and one’s proximity to large objects. Time runs more slowly on the top of a mountain than at sea level (so mind where you put your atomic clock!). Your toes are younger than your tongue! And at the centre of a black hole, where a singularity exists, time stops completely.
Finally, Colin Stuart touched on Quantum Physics. Quantum Physics deals with things at a very small scale, whereas Gravity is on a very large scale. Right now, of course, we still can’t unify these theories – when and how do you need to switch from Quantum Physics to Relativity? The Wheeler-DeWitt equation attempts this, to mathematically combine the ideas of quantum mechanics and general relativity, a step towards a theory of Quantum Gravity. But in this equation, there is no mention of time! Indeed it hints that time does not exist, it is merely an illusion we perceive.
If time exists, then we have no free will. Of course, if time doesn’t exist, then, oh yes, we do!
Sandy Giles
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