It was a personal tragedy that started the timeline. After Boyd Mallett died of a sudden heart attack in 1955, his 10 year old son, Ronald, made a promise: he would find a way to travel back in time to warn his father of what was going to happen. It was a mission inspired partly by a copy of H.G. Wells' The Time Machine, which Ron discovered a year after his father's passing.
The story follows the narrator's journey into the future, but one line in particular struck Ron: "Scientific people know very well that time is just a kind of space and we can move forward and backward in time just as we can in space." He believed that he could build a fully working time machine to go back in time and so he dedicated his future to proving it.
"For me the sun rose and set on him," says Mallett about his father, a television repairman who was just 33 when he died. Ron kept his research into time travel a secret for many years for fear he might damage his credibility. Sadly, that prevented him from reaching out to people who might have been able to help him.
Now aged 69, Ron Mallett, a physics professor at the University of Connecticut, is totally candid about his research, but he still hasn't reunited with his father and most likely never will. But he has an equation that he believes holds the key to building the first time machine and he might be close to a breakthrough.
A theory of flying clocks
Like most time travel theorists - Kip Thorne and his wormholes being one of the best known - Mallett anchors his idea in Einstein's theory of relativity. If you're not already familiar with it, there are two parts you need to know about. The first is called special relativity, which says that the speed of light is constant for everybody. By the theory of special relativity, time will pass slower the faster a person moves. If you alone could travel fast enough to a distant star, you would age slower than everyone else on Earth, arriving back home in a younger state - essentially travelling through time.
"This form of time travel has been actually been achieved on a limited scale using fast-moving planes and hi-speed subatomic particles," says Mallett, referring to an experiment carried out by the US Naval Observatory in 1971. Four clocks were flown twice around the world - eastward and then westward - at the speed of sound. When they were observed on return it was found the airborne clocks had lost a small amount of time compared to the ones that were kept on the ground. Were the clocks put in a rocket flying closer to the speed of light, the effects would be more dramatic.
The second part of Einstein's theory is called general relativity - if you've ever used a GPS unit in your car then you've (possibly unknowingly) experienced its effects. General relativity says that gravity can slow down time - meaning a clock on a satellite runs faster than one on Earth - which is why the frequency standard on each satellite is offset to make it run slower before being launched into space (in fact, satellites have to account for both special and general relativity due to the speed they're moving at, but the magnitudes aren't equal and therefore don't cancel each other out, hence the need for them to be altered before launch).
If you've seen the film Interstellar, you'll recall how it portrayed the effects of gravitational time dilation on a dramatic scale as the characters' ages fell out of sync with one another.
Einstein believed that light and matter could create gravity. Mallett's breakthrough was a theory that claims if gravity can alter time and light, and light can create gravity, then light can also alter time. So he designed a machine that would use lasers to twist time and bend it back on itself to form a loop. By Einstein's theories, time and space are linked - and so if you affect space you will eventually affect time.
"By using a circulating beam of laser light, I have been able to mathematically show that this can lead to a twisting of space and time," says Ron. "By twisting time into a loop. It could be possible to travel back in time."