If you weren’t already aware (and every self-respecting Geek should know), today – 15th October 2015 – is Back To The Future Day, the day Marty McFly and Doctor Emmett Brown visited in the original film, which was released way back in 1985.
To celebrate BTTF day, ride-sharing company Uber in conjunction with Pepsi Max, offered its London users the chance to take their ride in a real DeLorean, simply by entering a promotional code into the Uber app.
Sarah Brightwell, senior marketing manager at Uber, said:
“We may not be able to travel through time but at Uber, we’re all about looking to the future. We’re thrilled to be marking Future Day with Pepsi Max by bringing fans an iconic ride at the touch of a button; a nod to a cult 80s film using today’s brands and tomorrow’s technology.”
So, what’s the answer to the main question asked by the BTTF films? Is time travel actually possible?
Yes – and no.
According to Einstein’s Theory of General Relativity, time travel into the future is definitely possible – although you’d either need a very fast spacecraft or a black hole to do it! Here’s how:
Simply (!) accelerate your spacecraft to as close to light speed as possible (186,000 miles per second, if you want the figures), and travel for as long as you wish to travel (20 years, perhaps)along a circular course that will bring you back to Earth. When you finally return, 20 years will have passed on Earth, while you wouldn’t have aged noticeably as a result of relativistic effects (which is just a fancy way of saying ‘”time slows down as you approach the speed of light”).
It’s a well-known fact in Geekdom that once you pass the event horizon of a black hole (the region where gravity is so strong, even light cannot escape its pull), there is no way back. However, if you were to pilot your spacecraft close to the event horizon (but not so close as to be sucked in), when you return to Earth, more time would have passed for those you left behind (this is a result of the extreme gravity and spacetime warping that occurs near a black hole).
So what about time travel to the future? Unfortunately impossible, according to physics. Whilst the mathematical equations of Einstein’s Theory of General Relativity can be solved in ways that seem to permit time travel into the past when taken on their own, when combined with other theories – Quantum theory for one – these solutions break down. As Dr Christian Boehner from University College London (UCL)’s Department of Mathematics puts it:
“Sometimes you can find solutions that are quite weird. Some equations have a lot of solutions but many are disregarded as they have properties that are undesirable. That’s how time machines become disproved. The mathematical equation is sound but it disagrees with too many principles we uphold.”
Are you doing anything to celebrate BTTF day? Let us know about it in the comments!