Home ›› 06 Apr 2022 ›› Opinion
Ron Mallett has a dream: He wants to travel in time. This isn’t mere fantasy - Mallett is a respected professor of physics. “I think of myself as being an ordinary person with a passion, and my passion is the possibility of time travel,” he says. Prof Mallett has wanted to build a time machine for most of his life. His passion, he explains, can be traced to a tragic event early in his life. Ron’s father, a heavy smoker, died of a heart attack at the age of 33 - when Prof Mallett was just 10 years of age. Ron was devastated and withdrew into his books.
“A year after that when I was 11, I came across the book that changed everything for me. That was The Time Machine, by HG Wells,” the University of Connecticut physicist told the BBC’s Horizon programme. “The cover caught my attention, but it was when I read the inside, and it said: ‘Scientific people know very well that time is just a kind of space and that we can move forward and backwards in time, just as we can… in space’.
“When I read that I said: ‘This is wonderful!’.” Prof Mallett explains: “If I could build a time machine, then I could go back into the past and see my father again and maybe save his life and change everything.” Time travel may sound far-fetched, but scientists are already exploring several mysteries of nature that could one day see Ron’s dream fulfilled. Albert Einstein thought the three dimensions of space were linked to time - which serves as a fourth dimension. He called this system space-time, and it’s the model of the Universe that we use today. But Einstein also thought it was possible to fold space-time, creating a shortcut between two distant locations. This phenomenon is called a wormhole, and it can be visualised as a tunnel with two openings, each emerging at different points in space-time. Wormholes might exist naturally in the cosmos; indeed, scientists in Russia are trying to use radio telescopes to detect them. But using wormholes for time travel won’t be straightforward. The nearest ones could be many light-years away. And even if you could get to them and then survive the journey through them, there’s no guarantee where you’d end up. But some physicists have speculated that we might be able to conjure up bespoke wormholes at some point in the future - though we currently have no idea how. Physics also predicts that wormholes would have a habit of collapsing, crushing whatever’s inside them. If a time machine is ever to exploit them, we’d have to find a way to stop this inconvenient feature.
The mysterious phenomenon of dark energy might provide a solution. In the 1990s, astronomers found that the expansion of the Universe was speeding up, rather than slowing down as might have been expected. “Something out there is having an ‘anti-gravity’ effect - it’s pushing rather than pulling. We don’t know what that is, but it makes up most of the Universe. We call it dark energy,” says Prof Tamara Davis, a cosmologist at the University of Queensland in Australia. A wormhole will only work for time travel if its “mouth” can be held open for long enough that it allows something to travel through it. That requires something called negative energy, which doesn’t really exist in the everyday world.
But the dark energy that permeates the cosmos fits the bill - if we can figure out what it is, we might be able to prop open a wormhole long enough to go in one end and out the other. “We don’t know whether we are able to make a wormhole, whether that’s technically within our capabilities… But who knows what a future human civilization is going to be able to do,” says Prof Davis. “Technology has advanced so rapidly that maybe space and time themselves are something that can come under our control.”
Wormholes exist at the more speculative end of physics, offering one approach to travelling in time. But Ron Mallett has another. He has drawn up plans for an actual time machine, and his concept was inspired by a book he read at age 12 about Albert Einstein’s equations.
BBC
