It’s been written about in hundreds of literature, the subject of imagination for everyone at one point or another. The government has committed to studying the issue at one time or another.
If you search on the Internet for time travel, you will discover millions of entries and hundreds of websites devoted to talking about it. Wouldn’t it be fantastic if you could travel back in time? You may repair mistakes you’ve made in your life, study any era of time that interests you, not mention construct a financial empire on your foresight of events. Beginning with H.G. Wells’ The Time Machine, the notion of time travel has been one of the fundamental mainstays of science fiction. My favorite novels include David Gerrold’s The Man Who Folded Himself and The Light of Other Days by Stephen Baxter and Arthur C. Clarke.
So, is it feasible to travel in time?
First of all, we are already time travelers because time marches ahead and at the same apparent rate of speed. There seem to be no hurdles in physics to increasing the forward momentum of time in one manner or another. Cryogenics is a notion often talked about as one form of “forward” time travel; decreasing the body temperature to a little above absolute zero to practically stop the metabolism as a way to sleep away millennia—the practical barriers to this push any likelihood of this well into the future. Although smaller species have been successfully frozen and recovered, the human body is too complicated to withstand the technique because of water crystallization and other issues. Another means of speeding time is time differentials due to high velocity’s relativistic effects.
According to Einstein’s Theory of Relativity, as an object approaches the speed of light, one of the effects is time dilation. As a relativistic object’s speed rises, the passage of time slows for it concerning a non-moving thing. Take, for example, a spaceship flying at 10 percent of the speed of light, or 18,628 miles per second. If this fictional spaceship maintained this speed constantly for 24 hours (according to our clocks back home), then at the end of that 24 hours, just 23 hours, 53 minutes would have elapsed onboard the spacecraft. Much greater speeds to within a fraction of a percent of the speed of light need to be obtained to create a genuinely significant effect. Take the identical ship and accelerate it to .999999 light speed (or to 186,281.81 miles every second), and something extremely odd happens, attaining something more like time travel. If you take that ship out on a joyride at that speed for 24 hours of your traveler’s time and come home, you will find that almost two years have passed on earth.
This has been demonstrated in studies done when atomic clocks were sent aboard jetliners to examine time dilation effects. The discrepancy was detected as expected, helping to confirm Einstein’s ideas. Naturally, the difference was minimal, measured in nanoseconds. Unfortunately for any aspiring time travelers, the type of speeds needed for relativistic effects is still well outside our technology. The fastest spacecraft yet launched was the Helios spacecraft sent to investigate the sun in the 70s. They attained roughly 158,000mph or about 44 miles per second; this is about .02 percent light-speed, yet not near relativistic speeds.
And what about the chance of journeying back in time?
This creates fantastic fodder for science fiction, but the evidence here doesn’t look encouraging. Physicists have been able to imagine some scenarios under which time travel MAY be possible under the rules of physics. Still, the energy levels and exotic matter requirements seem beyond anything we are likely to achieve anytime soon. Some have proposed that wormholes may be bridges to other worlds, remote areas of this realm, or other timelines. However, wormholes remain a theoretical idea, neither confirmed nor disproven to exist. For all practical purposes, the cosmos has (at least temporarily) denied us the chance to revisit our history firsthand. So let us proceed to a consideration of what the possibilities might be if time travel did exist.
First of all, we must look at the fact put up by current physics that space and time are connected features of the topology of our universe. In other words, our world comprises the three visible dimensions of space and one time. Putting together a hypothesis that explains the existence of our universe involves integrating time and space into one continuum. Assuming this to be accurate, there should be a parallel measurement in space corresponding to measurements in time. It may seem illogical to talk of measuring distance in seconds or time in miles, yet the speed of light connects the two. Therefore, to translate one second into space, we look at how far light goes in one second. That would be around 186,282 miles or three-quarters of the moon’s distance. This indicates that going one second back in time would be comparable to traveling almost the distance to the moon. Then there is the reality that a change in temporal location would entail needing to account for the movements of the earth, sun, and galaxy as they spin and circle. A lot tougher than it appeared, huh? Ok, let’s say we overcome this issue and accomplish actual, significant time travel. Could you travel back in time and murder your grandfather early in life, ensuring that you would never be born? Time travel is complete with paradoxes such as this. For the most part, this may be avoided by introducing quantum physics into the notion of time travel and branching worlds.
Quantum mechanics is an area of a theory that evolved in the first part of the twentieth century via the work of Niels Bohr, Pauli, Planck, Heisenberg, and Schrodinger. Its central beliefs are that matter exists as a cloud of uncertainty and probability at a fundamental level. For example, Heisenberg’s Uncertainty Principle asserts that one cannot measure both the location and momentum of an elementary particle since the act of observation alters the outcome. In this branch of physics, cause and effect are said to break down, and one can only state the probability of something being true. The most famous example of what quantum mechanics means in the real world was given as a thought experiment by Erwin Schrodinger and is known as Schrodinger’s Cat. Here it follows:
A cat is placed in a sealed box. An apparatus containing a radioactive nucleus and a canister of poison gas is attached to the chest. This apparatus is separated from the cat so that the cat can in no way interfere with it. The experiment is set up to have exactly a 50 percent chance of the nucleus decaying in one hour. If the nucleus decays, it will emit a particle that triggers the apparatus, opening the canister and killing the cat. If the nucleus does not decay, then the cat remains alive. According to quantum mechanics, the unobserved nucleus is described as a superposition (meaning it exists partly as each simultaneously) of “decayed nucleus” and “undecayed nucleus”. However, when the box is opened, the experimenter sees only a “decayed nucleus/dead cat” or an “undecayed nucleus/living cat”.
The paradox of this experiment is that the cat is said to be both dead and alive until someone opens the box. (*No cats or animals of any kind were harmed in the writing of this article). This paradox can be resolved if we say that instead of both being true in one reality, that reality branches into two. In one universe, the cat is alive, and in the parallel universe, it is dead. In this way, our universe is constantly splitting into alternate universes in which every possibility is encompassed. This also solves the paradoxes of time travel. When our time traveler returns and makes changes in the past, he would be creating an alternate universe without destroying the other. In this way, as he or she continued to make changes, our time traveler would never be able to return to their original timeline, although he could create one similar to it with the right differences. The possibilities and repercussions of a scenario such as this are spectacularly presented in the science fiction novel The Man Who Folded Himself by David Gerrold.
In summary, time travel is a highly entertaining concept for science fiction and holds some plausibility in particular notions of modern physics. But as a practical application, it is not likely to become a part of our lives anytime soon. But, of course, not a time traveler myself.
Time will tell.