Let's face it, all of us, given the chance would like to travel through time. Whether it be backwards, to witness some incredible event of the past (the birth of Jesus, the Battle of Hastings, Leicester winning the Premier League), or forwards, to see what our Matrix-style virtual reality future actually looks like.
But is it actually possible?
Einstein's theory of General Relativity has already confirmed time travel of sorts - moving at different speeds causes people to experience the passing of time at different rates - while wormholes, and the possibility of travelling vast distances instantaneously - thus saving time on a traveller taking the 'traditional' route - are a theoretical possibility. Both of these, however, are one-way into the future, and require travelling at close to the speed of light - not really a practical measure. Meanwhile, there are all sorts of issues with causality and paradoxes - as beautifully illustrated by the likes of Back To The Future.
However, one man believes he may have cracked it.
Ronald Mallet is a 71-year-old theoretical physicist at the University of Connecticut, who is the subject of a new documentary directed by Spike Lee entitled How To Build a Time Machine. Premiering at the Hot Docs Film Festival in Toronto, you can see an early trailer above. He was inspired to begin his journey by the death of his father, when he was aged just 10.
He states, "I would say it was fair to call what I was doing an obsession. I was obsessed with wanting to see my father again. I was obsessed with trying to find out how one could control time. Everything that I became, the whole of my personality, everything about being a physicist, was based on my love for my father, and my desire to see him again.
"I had a mission. My goal was to figure out how to build the time machine. My whole existence, who I am, is due to the death of my father, and my promise to myself to figure out how to affect time with Einstein’s work as a foundation. I’m the theoretical guy. The experimental physicists will have to take on the daunting – and very expensive – role of testing my theory."
And what is that theory?
Mallett has spent nine years creating and refining a 'machine' based on the fact that light can create gravitational fields, writing in a paper that, at sufficient energies, "For the strong gravitational field of a circulating cylinder of light, I have found new exact solutions of the Einstein field equations for the exterior and interior gravitational fields of the light cylinder. The presence of closed timelike lines indicates the possibility of time travel into the past. This creates the foundation for a time machine based on a circulating cylinder of light."
He believes that physical time travel is impossible, but that messages could be sent through time, by utilising neutrons sent through a tunnel of light.
"By assigning a 1 to the ‘spin up’ direction and a 0 to the ‘spin down’ direction then [we] could send a binary code with a stream of neutron spins. For example, neutrons with ‘spin up’, ‘spin down’, ‘spin down’ would represent a binary code 100 which is the number 4."
So, essentially, not a million miles away from the communication seen in Christopher Nolan's 2014 epic Interstellar.
So will it work? Well, it's grounded in good science, but some fellow scientists have criticised his work - check out his Wikipedia page for details.
For now, we'll just have to hope Mallett can be our very own Doc Brown in the coming years.