The world’s longest-running science fiction show has its 50th anniversary on 23 November. In case you don’t know, it concerns a 900-year-old alien humanoid known as the Doctor, who travels through space and time in a vehicle called the Tardis. Oh yes, and he has the ability to regenerate 12 times, according to legend, each time in a different body. To mark the occasion, we line up the fiction with reality
1. Time travel options
This one is, admittedly, tricky. The Tardis travels through the “time vortex” to reach past and future destinations, and it might just be possible for us to do the same. General relativity says that tunnels called wormholes can link two distant points in the universe. Sending one end of the wormhole flying at the speed of light causes it to age more slowly than the other, so travelling through the wormhole would send you back in time. You would need a new wormhole for each destination making it hard to go on spontaneous trips like the Doctor.
Theorists have also recently proposed a way to design bubbles of space-time using exotic matter that mimic a Tardis but it can only travel in loops through time, which would get pretty boring after 50 minutes, never mind half a century.
2. Ultrasonic screwdriver
With the ability to get out of any impossible situation, a device called the sonic screwdriver is one of the Doctor’s most important tools. In the real world, ultrasonic devices are able to levitate and manipulate particles and liquid droplets, though they aren’t available in handheld form just yet.
3. K-9 turned up to 11
During some incarnations of the Doctor’s life – did we mention that he periodically regenerates into a different body? – he has a loyal robotic dog, called K-9.
The dog on television might have had a laser, but it was limited to trundling around on wheels. Boston Dynamics of Waltham, Massachusetts, has a much better artificial canine, dubbed BigDog, that can run on four legs and even recover from a stumble. If you prefer cats, the company also has a faster bot, Cheetah, which can reach speeds of nearly 30 kilometres per hour.
4. “It’s bigger on the inside!”
It’s rare for anyone to enter the Tardis for the first time without uttering some variation of the above phrase. From the outside, the Doctor’s time machine appears to be a wooden Police telephone box, similar to those seen in 1960s London. But on the inside… it is vast. Perhaps infinite. Surely it’s not possible to squeeze an infinite space inside a small blue box? Well, it sort of is, with a little help from a virtual reality headset. Researchers at the Vienna University of Technology in Austria have created a simulator that generates endless rooms and corridors. The device tricks users into walking around a much smaller space in the real world by making them turn before they hit a wall.
5. Home of the Time Lords
In the original run of the TV show, Gallifrey, the Doctor’s home planet, was one of a number of worlds orbiting a binary star system, though its whereabouts have varied since Doctor Who returned to the small screen in 2005. At the moment we only know of a single binary star system with multiple orbiting planets. Last year astronomers announced the discovery of Kepler-47b, a planet three times the width of Earth, and its neighbour 47c, a gas giant. The latter is in the system’s habitable zone, where temperatures are right for liquid water, so Time Lords could lurk on any of moons orbiting the planet.
6. Pick a card, any card
The Doctor sometimes uses a handy gizmo he calls psychic paper – it looks like an ordinary blank card, but when the Doctor presents it to someone, they see it printed with whatever he wants them to. Useful when he’s caught in places he’s not supposed to be. You can get a similar effect by employing the choice blindness illusion, a psychological experiment in which volunteers are asked to pick one of two options, such as selecting the more attractive of two faces, and justify their choice. When the experimenter uses a card trick to secretly swap their choice, 75 per cent of people don’t notice it is the complete opposite of their original preference.
7. Interstellar travel
As of last year, this is a reality – sort of. NASA scientists say that the Voyager 1 space probe left the solar system in August 2012, making it the first human-made object to reach interstellar space. It took 35 years to get there.
However, Voyager 1 is going rather too slowly to reach another star anytime soon. If we want to travel to the stars, we will need much faster propulsion methods than chemical rockets. That might mean ramjets that gather fuel from deep space as they travel, powerful fusion rockets, or something nobody has thought of yet.
Plenty of animals can completely transform their bodies: you only have to think of caterpillars metamorphosing into butterflies. But there are limits, and these shape-shifting animals only go through a fixed number of changes before their final “adult” stage. At this point, they breed and soon die.
One species, however, takes regeneration to a whole other level. The immortal jellyfish can keep metamorphosing indefinitely. The larvae of Turritopsis dohrnii first form colonies of polyps, and sexually mature jellyfish then bud off from these. But a 1996 study revealed that the adult jellyfish can transform back into sexless polyps, and these can later become adults again (Biological Bulletin, doi.org/bf95d6).
Assuming the animal doesn’t get killed, it seems to be able to keep regenerating forever.
9. Man with two hearts
The Doctor’s species of humanoid is fortunate enough to have two hearts. This condition sometimes turns up in humans – George Lippert, for example, apparently had two hearts and three legs – but in plenty of other animals multiple hearts are the norm.
For instance, cephalopods – squid, octopuses and the like – have three hearts. Two pump blood through the gills, where it picks up oxygen from the surrounding water. The third heart pumps the oxygenated blood around the rest of the animal’s body.
Meanwhile, earthworms have crude versions of hearts called aortic arches. Typically, each worm has five pairs of these, lined up just behind its head.
10. Perceive the geometry of space-time
Einstein envisioned the structure of the fabric of reality like no one else ever had – but a small percentage of people can perceive time as a spatial construct just like the Doctor. Just get yourself a dose of time-space synaesthesia. Synaesthesia occurs when the senses are mixed, so that, for example, a sound or a number has a colour. In the time-space version, people perceive the months of the year as shapes.
11. Know your enemy (i): The Daleks
If you want to be a Time Lord, you’ll also need an arch-enemy. The Doctor’s nemesis is a race of machines with an organic core called the Daleks. But organisms that combine living creatures with mechanical devices are a reality. People have learned to control prosthetic arms using the power of thought,with a bit of help from brain scanners and so have monkeys. Such technology could help paralysed people move.
It is even possible to replace parts of the brain with digital equipment, which could help older people stay mentally nimble for longer. In a proof of principle, a group of lab rats had their cerebella replaced with artificial, electronic versions.
Engineers have also built cyborg insects that can be remotely controlled and used as spies. The latest nerve probes can control moths as they fly around.
So far, none of these cyborgs has been fitted with a sink plunger.
12. Know your enemy (ii): The Cybermen
The cybermen are a nasty bunch of yobs – once human, they are now emotionless creatures that have been stripped of their personalities. Common in science fiction, such animals are rare in reality. In fact, emotions and personalities are extremely widespread in the animal kingdom, even in those without brains, such as sea anemones.
It is a myth that having no emotions makes you more rational. In fact, our emotional reactions are valuable aids to decision-making. What’s more, the brain centres that process emotion in humans can also be found in many animals, suggesting they can feel pleasure and other emotions. We recommend, therefore, that should you encounter cybermen you appeal to their compassionate side.
Authors: Jacob Aron, Michael Marshall