“If my calculations are correct, when this baby hits 88 miles per hour, you’re gonna see some serious s***.” – Dr Emmet Brown from Back to The Future (1985)
Would you believe me if I told you Dr Brown was actually cooking something?
Well, the reality is it isn’t exactly 88 miles per hour (more like 300000000 m/s but we’ll get to that in a minute) and it probably won’t be done in an awesome car from the ‘80s however there have been theories and speculations from various physicists on the ever so remote possibility of being able to travel through time.. But how would that even work?
If we could ever come across the technology to be able to travel through space and time near the speed of light (it’s impossible for anything to travel equal or above the speed of light), the obvious thing would be of course the privilege gained to voyage different areas within our solar system extremely quickly; almost invalidating the use of hyper sleep (as seen in several films such as ‘2001: A Space Odyssey’ when they travel to Jupiter). However, a major consequence arrives due to the sheer speed at which you are moving. Time dilation.Brief info on Time dilationEinstein proved that the faster you move, time slows down. Using the example from the article from amnh.org, “Five years on a ship traveling at 99 percent the speed of light (2.5 years out and 2.5 years back) corresponds to roughly 36 years on Earth.” This essentially indicates that by travelling near the speed of light, time moves significantly slower in your perspective than for others so you are in a sense moving towards the future but for everyone else, time would pass normally and they would age and eventually die while you age at a much slower rate. So through Einstein’s theory of Special Relativity you could indeed technically travel to the future(but you’re basically just travelling ahead in time very quickly). A really good explanation for the concept of Time Dilation can be found in another physics article here: https://www.phaselearning.org/post/time-holds-hands-with-everyone
But what about going back in time…
Temporal Paradoxes
There are several distinct time travel paradoxes that unfortunately demonstrate the impossibility of being able to go backwards in time. Since they’re slightly difficult to understand I’ll look at 2 common ones: The Bootstrap paradox and The Grandfather paradox.
The Bootstrap paradox is where an object or piece of information is sent to the past and becomes the source of its own existence which makes our conceived notion of causality (relationship between cause and effect) quite fuzzy because if an object has no clear origin and just seemingly came into existence from nowhere, that is deemed paradoxical by the standards of basic causality. An example would be if you travelled back in time and gave prolific thriller writer Stephen King his books before he writes any of them thus it exists in a ‘closed loop’. What’s a closed loop? In this context it’s just events or certain information lacking a clear beginning/cause since the effect (the published books) is also its own cause of existence. And finally (and arguably the most well-known), the Grandfather Paradox. It’s where information changed in the past can create a contradiction. For example, if you somehow tampered with the events which lead to say your parents or grandparents meeting, you would not be born and so, how would you have been able to time travel in the first place? Another can be the famous implication of travelling back in time to murder Hitler whereby doing so, you remove any reason for your future self to go back in time in the first place. It’s not as simple as how it is in ‘Avengers: Endgame’ (2019) where changes in the past can create alternate timelines as in reality, the creation of a loop of events is logically implausible.
So.. it seems travelling forwards in time is the only thing that sort of makes sense which is a shame since it’s safe to assume a lot of people would also like to travel back in time to perhaps fix mistakes. I think Neil from Christopher Nolan’s 2020 film ‘Tenet’ said it best: “What’s happened, happened. Which is an expression of faith in the mechanics of the world.”
Move on from the past, look towards the ever so uncertain future.
F.Y.I Didn’t expect to end off on such a dramatic note.
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