(Originally published on June 15th, 2014 on The Wannabe Scientist.)
Time Travel. An alluring concept that has been tampered with in science fictions, ranging from The Time Machine by H.G. Wells to popular TV shows and movies such as Back to the Future trilogy, Star Trek, and my favorite, Doctor Who. It has always seemed to be so easy: it seems like time travelers can just go into a fancy machine, push a button, and travel back to the past to correct a fault or to the future for a vacation. However, the reality is not so simple.
So, will time travel ever be possible? To really dig into this difficult(1) question, we must first take a glimpse of the complications involved. First of all, to understand how time travel might be feasible at all, you might want to dabble a little bit in the theory of relativity. I imagine you don’t want to chug through pages of explanations, so I’ll put the main idea here, summarized nicely by Wikipedia: “relative to a given observer, time passes more slowly for bodies moving quickly relative to that observer, or bodies that are deeper within a gravity well.”
What does that mean?
It means that your roof is traveling in time faster relative to your basement(2); it also means that if you’re moving, you’d be traveling in time faster in relation to a thing that is stationary (in a given observer’s point of view). Great. So why isn’t a time machine invented yet?
Well, to make a significant (and noticeable) difference in time, you would need immense gravity (we’re talking about traveling near the event horizon of a black hole here) or extreme velocity. (as in, near the speed of light) The first is obviously not doable, and the second is doubtful–as you can see below, the kinetic energy vs. speed graph is not linear; in fact, as we approach the speed of light, the energy required to do so approaches infinity. The theory of relativity states that nothing can be faster than the speed of light. (And we’re talking about 186,282.397 miles/sec here.)
Even though time travel is plausible if we just speed up our aircraft fast enough for us to realize the difference in how the time flows in the aircraft and out of the aircraft, the energy required is so immense that the technology would not be developed for another long while, if ever. Scientists are having enough trouble to speed single particles to near the speed of light and observe their behaviors as it is.
It is, however, said to be another way. It is theorized that if the fabric of space and time is folded together and connected through a wormhole (as seen in the picture, it is a compilation of a black hole and a white hole, whose existence has not been proven just yet), then time travelers could go through the two ends freely and travel back and forth these set space and times. However, there is no tangible evidence for this theory–all we know is that due to black holes’ immense gravity, wacky stuff that contorts time and space happen, and something like wormholes might just come out of it.
Time travel is a concept that we have toyed with and thought about throughout these past few decades as quantum physics and general relativity comes about, but this concept is so abstract (even to physicists) that much research still has to be done for us to even be able to scratch the surface of understanding. But until then, all I can say is “Allons-y!”.
(1) Which is a huge understatement–scientists have been wondering about this for a very long time and the mathematics involved can drag on for pages
(2) Actual research has been conducted to prove this fact, read here for more info: http://www.dailymail.co.uk/sciencetech/article-1314656/Scientists-prove-time-really-does-pass-quicker-higher-altitude.html