Is time travel really possible? The secret science that explains Doctor Who

Is regeneration real? Could alien life be out there? And how does the sonic screwdriver actually work? gets the answers from two experts...


Given that it’s a show about a two-hearted alien who travels through time and space in a police box, you can be forgiven for thinking that Doctor Who is a tad far-fetched. Yet what if its most weirdest, most timey-wimey sci-fi concepts weren’t actually fiction at all? What if, beyond the Tardis, there was actually some scientific fact involved?


In their new book, The Scientific Secrets of Doctor Who, Simon Guerrier and Dr Marek Kukula seek to answer just that; exploring the possibilities of time travel, life on other planets, artificial intelligence, parallel universes and more. In doing so, they show how Doctor Who uses science to inform its unique style of storytelling – and just how close it has often come to predicting future scientific discoveries.

Guerrier and Kukula will be revealing some fascinating facts about the science of Doctor Who at the Radio Times Festival later this month, so sat down with the pair to ask the question: just what in Doctor Who is scientifically possible?

Is it possible to actually regenerate?

Yes, regeneration really happens. If you cut or burn yourself, your skin will regenerate and heal. But the regenerative abilities of humans are limited.

Other creatures, such as octopuses and crabs, can regenerate lost limbs. (Octopuses also have blue blood and three hearts, so they’re quite like Time Lords.) We know this is to do with a biological process where undifferentiated ‘stem’ cells in the crab or octopus can change into specialised types of cells, which is useful for repairing damage. You could think of these stem cells as like the blank tiles in a game of Scrabble, which can be used as any letter to complete a word. Understanding this process is useful to humans – we can already use stem cells to treat a wide range of diseases and medical conditions, such as cancer and arthritis.

Can creatures entirely regenerate their bodies, like the Doctor does? The ‘immortal jellyfish’, Turritopsis dohrnii, can. When it gets old or ill, it can revert to an immature polyp stage again. The equivalent would be someone in their 70s changing back to what they were like when they were 10. The immortal jellyfish seems to be able to revert like this many times and live for thousands of years.

Have a Doctor Who day out at the Radio Times Festival

The laws of time travel in Doctor Who are pretty fluid, with either the Doctor being able to change events in time or finding that they’re pre-determined. What are your thoughts on ‘fixed points in time’? Do they have any scientific ground? Or is it all timey-wimey?

We know that time is relative, which can have lots of strange effects. For example, due to the high speeds at which they’re orbiting the Earth, satellites and even astronauts on the International Space Station experience time passing slightly more slowly than we do down here on the planet’s surface. It’s only by fractions of a second, but we have to take that discrepancy into account if our sat nav or mobile phone systems are going to work.

As for fixed points in time, who gets to say whether one moment in time is more important than another? There’s certainly a debate among physicists as to whether time travel to the past might be possible and, if so, whether or not the laws of nature would prevent you from changing history and potentially creating a paradox. But in Doctor Who it seems as though this question might be more the province of philosophy or politics than science. In The Time Warrior (1973-4), the Third Doctor explains, ‘I’m a Time Lord … And my people are very keen to stamp out unlicensed time travel. You can look upon them as galactic ticket inspectors.’ So perhaps it’s less about the laws of physics and more about the laws of Gallifrey.


The Scientific Secrets of Doctor Who by Simon Guerrier and Dr Marek Kukulais out now, published by BBC Books, price £16.99 in hardback. Simon and Marek will be speaking at the Radio Times Festival on Friday 25th September at 5.30pm.