Back to School - Time Traveller's Academy

Congratulations, you’ve spent years training and you’re now ready to become a fully-fledged time traveler. No doubt fate, or indeed time travel, brought you to our website to buy some watches, and now you’re here looking around you may as well enrol in our quick course to discuss some of the problems associated with time travel and a little something called causality. Here we go.

The Grandfather Paradox

In this scenario, a time traveler goes back in time and accidentally, or perhaps intentionally, kills his own grandfather before the traveler’s parents can be born, thus preventing a future with his own birth, and thus the ability for him to travel back in time in the first place, yet there they are. Paradox or what? This is known as an inconsistent causal loop, and it’s not possible according to the generally accepted rules of causality, i.e. cause before effect, where the past must stay consistent and be exactly what it is, i.e. the past. One way of getting around this problem is the theory of having multiple parallel universes, where meddling with events in the past causes a split and the creation of a new universe, with a different future. Alternatively, by killing one's own grandfather you prevent your own birth, and therefore the possibility of killing your own grandfather, allowing your birth. A further paradox.

Consistent Causal Loops

In this time loop example, the cause-effect principle is upheld and consistent with events that have already happened and will happen. Any attempt to change the past still results in the known future events playing out. An example includes the terminator, in the film The Terminator, going back to kill John Connor, yet the very act of it’s going back in time leads to John’s parents getting together and creating John in the future. In this time loop, no attempt to alter the past changes the future, as the past is exactly what it is.

The Bootstrap Paradox

Similar to a consistent time loop this is where an item or information from the future travels back to the past, which becomes the same item that is passed from the past to the future. Confused? Here’s an example; in the film Back To The Future, Marty McFly plays the guitar at the school dance. Wanting to impress the folks he plays “an oldie” where he comes from – Chuck Berry’s Johnny B Goode. Chuck’s cousin, Marvin, is present at the dance and phones Chuck so that he can listen in on Marty play. Inspired by the sound he writes a song in the future, which Marty will eventually learn and play at the dance. So the paradox exists – who wrote the song, or was it just ‘there’ and part of history all along?

So there you have it, some of the more frequently known theories and problems with time travel. Now you’ve been here again it’s time to buy that special watch to steer your course through time, best of luck!