A Canadian physicist says he's figured out how to travel through time - not just forwards, but backwards.
But don't go plotting to kill your grandfather just yet. It might come as a surprise, but Ben Tippett of the University of British Columbia admits it's currently impossible to build a machine capable of doing what his equations require.
"People think of time travel as something fictional," says Dr Tippett. "We tend to think it's not possible because we don't actually do it. But, mathematically, it is possible."
Scientists have long known the laws of physics work fine no matter which direction time is running. But getting time to run backwards has so far eluded the world's greatest brains.
Dr Tippett's equations rely on bending more than just your mind - but space itself.
"In 'flat' - or uncurved - space-time, planets and stars would move in straight lines," he explains.
"In the vicinity of a massive star, space-time geometry becomes curved and the straight trajectories of nearby planets will follow the curvature and bend around star.
"My model of a time machine uses the curved space-time to bend time into a circle for the passengers, not in a straight line. That circle takes us back in time."
So it's not as simple as jumping in a DeLorean and accelerating to 88 miles per hour. Nor is it something you should be making time in your calendar for.
"While is it mathematically feasible, it is not yet possible to build a space-time machine because we need materials - which we call exotic matter - to bend space-time in these impossible ways, but they have yet to be discovered," says Dr Tippett.
He calls his mathematical model the Traversable Acausal Retrograde Domain in Space-time - or TARDIS for short. A "bubble of space-time geometry" moves "at speeds greater than the speed of light at times, allowing it to move backward in time".
"Experts in my field have been exploring the possibility of mathematical time machines since 1949. And my research presents a new method for doing it."
Dr Tippett didn't explain why the past doesn't appear to have been visited by time travellers from the future.
If you think you can wrap your head around his maths, you can check it out in the journal Classical and Quantum Gravity.