Today, I would like to take a detour and discuss a somewhat taboo, but fully engrossing, topic in physics academia, plainly put, time travel. On their own "time" and "travel" seem pretty simplistic, but when put together, they have the power to command a persons' full attention. I mean, who among us wouldn't change certain aspects of the past - a do over, if you will - if given the opportunity? I would wager to bet everyone would (even if they wouldn't admit it), but unfortunately, time travel is complicated by the fact that various potential paradoxes could arise. Then, we are met with the issue that, in order to travel back in time, we'd need to exceed the speed of light (an impossibility, despite one of the most sensationalistic claims of the 21st century). So, for the most part, time travel is nothing more than a pipe dream, BUT: The assertion was that if photons COULD do that, they would have free reign of the universe's past, present and future.
THERE'S ALWAYS A "BUT:"
Before you get disappointed, quantum physics may have the solution. Quantum entanglement, as we've covered in the past, shows that paired particles mimic their behavior over potentially infinite distances.It must be said that distance isn't the only dimension that is seemingly ignored by quantum entanglement. Research conducted by many different physicists has revealed that particle pairs can communicate with one another along the TIMELINE!
Let me just re-iterate that... not only is it theoretically possible to change the state of one particle on Earth, and another 3,000 light years away, but you can actually teleport to that particle 3,000 light years away, 3,000 years ago... or at least, that is what the research suggests is ultimately possible, in theory.
A DEEPER LOOK:
Now that I have your attention, let me explain how this actually works. It isn't time-travel as Hollywood has shown us, through movies like "TimeCop," "Terminator," "Back to the Future," or the quaint act of stepping inside a Phone-box á la Dr. Who.
It is, in fact, the transferring of identity from one particle in the present time, alongside entangled particles (they form a quantum 'bridge' that the connection is made over), to another particle anywhere else on the timescale, where the other entangled particle resides at that moment. A form of quantum cloning, if you will.
It relies on a quantum function known as 'post-selection' which essentially allows the probability of a future occurrence to be engineered into happening (perhaps we can liken this to a self-fulfilling prophecy). In quantum and mathematical fields, this is known as 'conditioning a probability space'. In the laboratory, this has been tested at very basic levels through the grandfather paradox (this paradox highlights one of many problems with time travel) and has reproduced a 25% success ratio in our 'dimension'. If you were really into your theoretical physics, you could make the assumption that the other 75% manifested in different dimensions or elsewhere in the multiverse.
GRANDFATHER PARADOX LOOPHOLE?
What the experiment actually showed was the universe's answer to the grandfather paradox - a sort of self-defense mechanism. Where the photon COULD travel back in time with an engineered 'quantum gun', but it COULDN'T kill itself, as the gun could not fire. But when the time travel FAILED, it could fire the gun. Such a natural mechanism as this could theoretically stop a time traveler from erasing themselves in history, by simply not allowing them to interfere with themselves, or anything that influences their lives (wider thinking here) that could prevent them from being moved back into the past.
To bring this back to Hollywood - one piece of science-fiction managed to mimic this purported quantum effect beyond its years... and that was 'Quantum Leap'. In this 1989 series, the lead character, Sam Beckett is 'jumped' into someone else's body, taking over their consciousness, whilst their consciousness is transferred to his body, back in the hypothetical present time. This is the potential of quantum teleportation down this particular avenue of exploration. Of course, other routes of time manipulation can potentially exist through multi-verse theories, wormholes, and black holes, but they simply are unapproachable currently.
Hat's off to Quantum Leap creator, Donald Bellisario, for getting his sci-fi very science and not very fiction!
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