Back to the father: the scientist who lost his dad – and resolved to travel to 1955 to save him

After losing his beloved father when he was 10, Ronald Mallett read HG Wells and Einstein. They inspired his eminent career as a theoretical physicist - and his lifelong ambition to build a time machine

Prof Ronald Mallett thinks he has cracked time travel. The secret, he says, is in twisting the fabric of space-time with a ring of rotating lasers to make a loop of time that would allow you to travel backwards. It will take a lot more explaining and experiments, but after a half century of work, the 77-year-old astrophysicist has got that down pat.

His claim is not as ridiculous as it might seem. Entire academic departments, such as the Centre for Time at the University of Sydney, are dedicated to studying the possibility of time travel. Massachusetts Institute of Technology (MIT) is working on a time-reversal machine" to detect dark matter. Of course there are still lots of physicists who believe time travel, or at least travelling to the past, is impossible, but it is not quite the sci-fi pipe dream it once was.