If you could climb onto the bicycle seat of a time machine, set the stroboscopic rotors spinning, the multi-coloured lightbulbs flashing and the feather-fringed canvas wings flapping up and down, would you pedal back to the early 1900s and kill Hitler?
Assuming you had access to the real deal – a Tardis, say – would such an act be possible?
Could we ever travel through time? That was Alasdair Richmond’s theme for Edinburgh Skeptics on August 18 in the cavernous, baking-hot bowels of the Banshee Labyrinth, on Niddry Street.
As far as philosophers are concerned, he concluded, we could indeed be able to find our way back to when Adolf was a lad. Sadly (or fortunately, depending on your own philosophies), as far as physicists are concerned, it’s not very likely. And even if we could get there, we couldn’t kill Hitler. That’s because, in this universe at least, he didn’t die until 1945 and, even though we may theoretically be able to travel to the past (philosophically speaking), we cannot change what has already happened.
So argued Dr Richmond, a graduate of Aberdeen University and teacher of philosophy at Edinburgh University who works in philosophy of time and science. Adding immensely to his credibility for many of the Edinburgh Skeptics present, his other claim to fame is that he was a losing finalist in the 1976 John Menzies “Paint A Doctor Who Monster” competition.
Our inability to make a mark on the past is not total, however, contended Dr Richmond. What if we were to take a current copy of Hamlet back in time and show it to a young Shakespeare, before he had written anything? What if the lad recognised the play’s merit and copied it, word for word, passing it off as his own? Now that might be possible, philosophically, as it would leave no mark on history as we know it today. It’s what the doctor (No, not The Doctor… the man at the lectern in the Banshee) describes as a causal loop.
Such forays into philosophy were intriguing but this listener was lost when it came to the physics. Among the references quoted were Minkowski’s Time and Light Cone, Godel’s Universe and Tipler’s Cylinder – all too much for some, though not for all the audience and it was clear who had done their preparatory reading and who hadn’t.
The problems with time travel seem to come down, mostly, to our inability to surpass the speed of light – a pesky critter, which seems to stymie many a scientific endeavour in the way greater crested newts have a propensity to turn up on site and put a stop to major building projects.
Dr Richmond concluded by indicating that, expert as he is, he would not bet HIS house on humanity ever being able travel in time: “Dr Who is for kids,” he said. “Brilliantly done… but for kids.”