It's about time for a change. The quest for eternity, an escape from time. Newton's time and Einstein's time, the return of the eternal return. The start of it all, it happens when it happens, when you least expect it.
Leaping ahead of time and then coming back amounts to traveling into the past. Gathering up our tachyons (hypothetical particles that would always travel faster than light), slipping into our tachyonic suit, we must see the bullet hit the target before the gun is fired. Even though locally a particle may never exceed the speed of light, globally its future might connect up with its past.
This possibility arises because a gravitational field implies that spacetime is curved, and the curvature might be great enough and extended enough to join a spacetime to itself in novel ways. If a universe has this geometry, an observer could travel around the universe and return to her starting point.
A timely solution, an interlude, a timescape. Perpetual motion, why time runs faster in space, the clock in the box. The echo that arrived late, that which lies beyond the end of time. The big bang, and what happened before it. What's a few billion years among friends?
Today, this February 29th, a Leap Day held in a Leap Year, some find themselves pondering the effects of time and her many mysteries. Is time travel possible? Is it possible to leap through time, into the past or ahead into the future? Empirically speaking, is technology at a place in which we might ask of it this question?
Time travel leads to logical contradictions, paradoxical loops which are impossible according to our understanding of causation.
One of the basic laws of logic is the law of non-contradiction, which states that something cannot both be true and false at the same time. To sit here, writing this article, only to someday travel back from the future at this very time to give myself some important message ... hold on, wait for it!
NOTHING
Nothing happened. See what I mean? It is not possible to have something not happen and also happen at the same time. In my case, if I were to travel back into time, I would have traveled to this precise moment while I am writing about time travel to prove to myself that it is not only true, but that the laws of logic are illogical.
Of course, one could argue that if I could someday travel back into time I wouldn't travel to this point, I would travel to a more important moment, but that's beside the point. Speaking as a Philosopher, I would say that 'p' cannot simultaneously be 'not p'.
The ancient Greek philosopher Zeno of Elea (490 B.C.E.) described what the Oxford philosopher Gilbert Ryle later claimed is the quintessential philosophical problem. What makes it interesting is that it's a logical problem that leads to a contradiction that seems to imply that something couldn't be true that our experience tells us must be true.
The problem is called Achilles and the Tortoise. Achilles, the great Greek sprinter, is to race a tortoise. Knowing that the tortoise will be much slower, he gives the tortoise a head start. Nice guy, right?
Now according to mathematics, whatever distance has been covered by Achilles as he races to catch up with the tortoise, there's a corresponding smaller distance covered by the tortoise. The problem is that the tortoise always moves away by some degree from Achilles however much closer he is to the tortoise. So it seems that logic tells us that Achilles can never overtake the tortoise, but we all know that reality tells us he can.
The Australian philosopher, David Lewis (1941-2000), tackled the problems of paradox in his article "The Paradoxes of Time Travel." He purported there are ways in which time travel stories can be seen as consistent, avoiding paradoxes. Lewis's implication is that time travel is logically coherent - that is to say 'possible'.
External time is the time line through which the girl must travel, and personal time is the time line that is always moving forward. So, the Universe's time is the external time through which we move around, but inside ourselves, our very particles have their own personal time in that they are always moving ahead (of time).
This draws a distinction between two kinds of time: external time and personal time. Returning to the girl who leapt ahead of time, she can do so in her personal time because she is not held or bound by external time. It is thus only external time that seems to us contradictory. When she leaps into the ether, she is merely following her own timeline.
To where she is headed, only she and time knows. The only true paradox is our inability to perceive simultaneously the concept of external from the perspective of internal. If we were to leap outside our internal perspective, we would be met with the external perspective, outside the finite lies the realm of the infinite.
If particles can be split, so too can time. Thus saying we can split a concept such as time into external and personal is entirely logical.
In philosophy two very commonly used notions are that of contingency and necessity and they're used in relation to truth. A contingent truth is one that could have been otherwise, and a necessary truth is one that could not have been otherwise. In order to sort the two, philosophers talk about possible worlds.
Possible worlds were introduced to philosophy by the German Enlightenment philosopher Gottfried Leibniz (1646-1716). He asserted that ours is "the best of all possible worlds." This idea was entertainingly ridiculed by Voltaire (1694-1778) in his satirical story Candide.
In the case of the girl who leapt ahead of time we have a good example of a possible world: one in which she leaps ahead of the present moment and as a result, a whole bunch of other things happen to her that weren't happening in this world. The events that happen to her might be magical and mystical, peaceful and enlightening, thrilling and awe-inspiring.
It is perfectly conceivable that the girl travels to the precise place in time where she meets her personal timeline and rejoins with it in her eternal quest, in a parallel universe where distinctions are blurred and possibilities are tangible. In a world of infinite possibilities, such as this, every point in time has its equal alternative.
As we glance over the divide between external time and personal time, we see ourselves reflected back in our search. Hypothesizing a parallel universe ahead of time might sound unusual, but sub-atomic particles tell us that the mysteries we consider can only be explained by the existence of parallel universes.
I would love to call myself an actualist, but this is an impossibility and thus illogical for without all the answers to life's many mysteries, I cannot fully actualize truth. For this reason, I follow the problem of time loops and the problems of time meddling only as far as they can co-exist with existence insomuch that they (theories) are held in that very same existence.
Whenever a time traveler travels ahead of us we (who remain) find ourselves standing on the cusp of eternity, staring out into the great divide, wondering where our our journey will take us ...
Wherever we are headed, time travel theories lead us back to the idea that all time travels in the same direction.
Wherever we are headed, time travel theories lead us back to the idea that all time travels in the same direction.
We are all components on the same cosmic clock,
the only difference between us is the minute hand.