Literature professor Simon John James and physicist Richard Bower were both involved in the curating the exhibition, Time Machines – the past, the future, and how stories take us there. Their conversations quickly revealed to them the many, wildly various, meanings of “time travel”. Here, they discuss how time travelling in literary and scientific terms might, one day, coincide. Simon John James: Richard, what does the term “time travel” mean for a physical scientist? Richard Bower: Time travel is the basis of modern physics, and, for anyone that looks up at the night sky, an everyday experience. When we view the stars and planets, we see them, not as they are now, but as they were in the past. For the planets this time delay is only a few minutes, but for most of the stars in the night sky, thousands of years. For galaxies, faint smudges of light made up of very distant collections of stars, the delay can be millions or billions of years. By observing the faintest galaxies with the world’s latest telescopes, we can look back through time and watch the whole history of the universe unfold. But this is not the most satisfying kind of time travel. It allows us only to gaze into the past as remote observers. One of the key challenges for modern physics is to determine whether it is possible to influence the past. Looking back in time. Roxana Bashyrova/Shutterstock.com One of the key concepts of Einstein’s Theory of Relativity is that objects exist in a long line in 4D spacetime, a unification of time and space. Although all observers agree on the length of the world line that connects two events, they may have different views about whether the events occur simultaneously, or at the same location but at different times, or a mixture of both. For example, while I sit at my desk to eat lunch, then work a little and get up to go home several hours later, a (very) fast-moving observer will see me whizz by eating lunch and immediately getting up to go home. In Einstein’s theory, time and space are mixed together: we cannot think of them separately. It therefore makes best sense to think of myself as always moving along that 4D world-line, travelling into the future at the speed of light. But is it possible to cheat the safeguards of Einstein’s theory and to travel backwards through time? At face value the answer is no, but then again, the science of earlier generations would have said it was impossible for mankind to fly. Perhaps all scientists need is inspiration and a cunning idea.
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