Good question! That really stretches my brain first thing in the morning! I’ve not been watching this lot of Doctor Who but I did watch it years ago when I was growing up. I always get the impression that Dr who is pretty well written so there are lots of chances for things to be “true”.
The most famous thing is time travel. Now whilst this feels impossible at the moment, there are theories that suggest it should be possible. You may have heard of Einstein and his theory of Special Relativity. He stresses there is a difference between a person doing the doing of an action and another person “outside” the action, who he calls the observer. He says if the difference in velocities ( this is a bit like speed) between these two is big enough then this could affect how long something lasts. In other words the time it would take you yourself to fly to the Moon would be different to how long I thought it took if I was watching you!……IF the difference between our movement was big enough……however this difference in velocity or speed would have to be close to the speed of light. So whilst in terms of maths we can show things like this are possible, we are a long way off making it happen in ” real life”.
Other scientists talk about things called wormholes which would let us slip through to the past. These are suggested by a theory called ” Quantum Theory”. Apparently some people have shown that these wormholes form and break all the time…….but the problem with these is how small they are…..much smaller than an electron…..and as you may already know electrons are so small that you can fit a billion trillion in a teaspoon! So unless we could get some shrinking powder wormholes aren’t going to be much help for me or you!
Are there any things in Dr who in particular that you were wondering about?