A physics student at the University of Queensland recently published a paper indicating they’d ‘squared’ the maths when it involves time travel. Not only should it theoretically be possible to travel back in time, consistent with the numbers, but you can do whatever you would like without making any fundamental changes in present.
In other words: the ‘paradox of time travel‘ might not be real.
The problem goes like this: your eccentric old scientist buddy turns a DeLorean into time machine . Before he can teach you ways to use it properly, he’s murdered by terrorists. While fleeing the scene in said DeLorean you mistakenly travel back in time to the month before your parents fell crazy &, whoops wouldn’t you knew it, you unintentionally screw things up. Now they could not kiss at big dance & ending up having kids, so your very existence hinges upon your ability to right the wrongs you’ve caused so you could get- back to future.
That’s the ‘paradox of time travel.’ Put less verbose: a time traveler’s actions in past could cause a ripple effect that creates their purpose for time travel either not exist in present they came from or causes the traveler themselves not exist (also called the ‘grandfather paradox‘).
According to Germain Tobar, the undergrad who crunched the numbers & wrote research paper titled “Reversible dynamics with closed time-like curves and freedom of choice” that was recently published in Classical & Quantum Gravity journal, back to future plot gets time travel all wrong.
Per the paper:
We have developed a characterization of deterministic processes in presence of closed time-like curves (CTCs) for an arbitrary number of localized regions. Our proofs have demonstrated that non-trivial time travel between multiple regions is according to the absence of a logical paradox as long as once the outputs of about 2 regions are fixed, at the most 1 way signaling is possible .
The big idea here involves CTCs, or closed time-like curves. These are direct descendants of Albert Einstein’s famous theory of relativity. Conceived by renowned mathematician Kurt Gödel, CTCs are essentially little time loops.
“Time-like curves” are any paths through space that are permitted for enormous particles like electrons, protons, or spaceships. “Closed” time-like curves are any paths that end up back where and once they started, hence closed curves in 4-dimensional world of space & time.
There’s evidence for CTC’s in classical reality. Take below picture for example:
We can infer that the ball is in motion. This shows that we understand the ball’s past states and it gives us the power to predict where the ball, unfettered, will end up . This means that the past is directly connected to present .
Where things get interesting is in concept that specific “whens” in past are directly connected to “whens” in present &, consistent with the research, these are basically immutable.
Dr. Fabio Costa, the 2nd author on the paper and Tobar’s supervisor on the project, posited in press release that this suggests time travelers wouldn’t be able to return in time & stop an event or occasion like the pandemic. Try as they could , the universe just won’t allow it.
According to Costa:
However if you stopped that individual from becoming infected—that would eliminate the motivation for you to travel back & stop the pandemic in first place.
This is a paradox—an inconsistency that always leads people to think that point time travel cannot occur in our universe.
In the coronavirus patient zero example, you would possibly attempt to stop patient zero from becoming infected, but in doing so you’d catch the virus & become patient zero, or somebody else would.
No matter what you probably did , the salient events would just recalibrate around you.
This would mean that—no matter your actions—the pandemic would occur, giving your younger self the motivation to travel back & stop it.
So there you’ve got it. If we combine Einstein’s theory of relativity with Gödel’s CTCs & Tobar’s math-based interpretation we’ve a recipe for butterfly-effect-free time travel.
That means we can all go bananas with time travel vacations & steps on as many prehistoric bugs as we would like . Now that we’ve got the science & math sorted, it’s an engineering problem right? Your move Elon.