An essay
What if you had the chance to go back and re-do a mistake you made once? From something with life-changing consequences, like going to college, to just stubbing your toe, if you could re-do it would you? Or what if you could go back in time and warn a loved one, hey, don’t smoke all those cigarettes, it really will kill you? In the movies we have seen what time travel can effect for people like Marty McFly. But is it even possible?
Note that this is all hypothetical, theoretical, speculative. We’re wondering in these days if time travel is even possible, and stories abound about what would happen if we could time travel. What would happen if you went back 60 years in time and accidentally killed your great grandmother? Would that mean that you were never born? If you were never born, how could you accidentally kill your ancestor? Captain Kathryn Janeway on Star Trek: Voyager said that such conundrums gave her a headache, and she avoided thinking about such paradoxes.
I love stories about time travel, from Back to the Future to Star Trek: Voyager and Star Trek: Discovery. So let’s take a look at whether scientists think such a phenomenon is even possible. But a word to the wise: the math is complicated and almost painful at times. Time Travel is a lot more fun in fiction!
Starting with the NASA website, some type of time travel may have a physics explanation and therefore be possible. If the math is correct, that doesn’t mean the process is feasible, but such technology could exist in the far future. If that is true, is it possible to control time travel and use it for research; could humans even go forward or back in time?
Traveling through life, we move at a speed of 1 second per second. That sounds funny, but it’s part of Einstein’s theories. However, clocks move differently on airplanes. Clocks on airplanes move infinitesimally slower than clocks on earth. The difference is in less than milliseconds, but it is different.
Conversely, we can look through time using telescopes to look into deep space. When we see stars at the edge of known space, we are actually looking at the light of those stars from several hundred years ago. (Details and source)
Albert Einstein theorized about time in his Theory of Relativity. He stipulated that both time and space are linked and that nothing can travel faster than light. According to Einstein, the faster you travel the slower you experience time. When scientists compared two clocks, one on the earth, the other in a fast-moving airplane, the clock on the airplane moved slightly slower in time than the one on the earth. More research would be needed to elucidate exactly how precisely this time varies. GPS satellites orbit Earth very quickly, which slows their clocks down by a very small amount.
This part of his theory is called The Theory of Special Relativity, which does acknowledge that time can pass differently under different circumstances. This would suggest that time travel MAY be possible (just not very likely).
The speed of light is calculated at 186,282 miles per second. So time travel could significantly slow down the passage of time if you were able to travel at the speed of light, meaning that you could stop travelling and find yourself 1,000 years in the future. But you wouldn’t be able to go backwards in time in this manner.
Currently our fastest space vehicle is the Helios 2 space probe, at 160,000 miles per hour. (The speed of light is approximately 670,616,629 miles per hour. So we’re nowhere near this. (The speed of light might be thought of as Warp One from Star Trek).
If you could travel faster than light, (not naturally but by folding space or using cosmic strings, see below), that would be known as superluminal travel.
A faster – than – light engine called the Alcubierre drive, is an idea for a warp drive engine that would work by folding space.
Speaking of warp drive, some scientists state that warp drive, or building an engine that can travel at or above the speed of light might be possible. (Einstein posited that nothing can ever exceed the speed of light). One way to provide a warp drive, would be to fold space, so that the space in front of the vehicle is folded up and the space in the back of the ship is “normal,” which forms a bubble in which the spaceship/probe takes a shortcut through space, thereby traveling faster than light because it goes further. The name of this theoretical technology is the Alcubierre drive. It’s named after Miguel Alcubierre proposed a method for changing the geometry of space by creating a wave that folds the fabric of space. This type of travel is thought to cost a huge expenditure of energy and mass and is not yet achievable. Plus, the theorists who came up with this don’t know how to stop the ship when you arrive at your destination/time. That’s a problem!
Above: a graphic of the theoretical Alcubierre Drive
An astrophysicist named Richard Gott proposed the idea of cosmic string in 1991. These strings loop throughout space, and in this theory, a craft could grasp and ride the string through these loops in the universe.
The only problem with this theory, which is both simple and elegant, and makes a lot of practical sense, is that cosmic strings are purely theoretical. They’ve never found one. Fingers crossed.
Another theory involves wormholes. Wormholes are a staple of sci-fi, including Star Trek (ST) from the original series to the most recent iterations (at this point Discovery and Picard); but also Star Wars and Stargate. An early ST: Voyager episode detailed the discovery of a tiny wormhole, in which a Romulan scientist goes through the wormhole to travel across vast swathes of space to the Voyager. Later, you find that the wormhole travelled through space, but also through time. But is such a wormhole possible?
Simplified graphic of a wormhole (folded piece of paper)
Various theories to explain how wormholes could be formed exist, most based on rather complex diagrams and mathematics. One simpler way to think of a wormhole is this. Think of a piece of paper, with a point drawn on one end of the paper (point A), and another point drawn on the opposite end of the paper (point B). They are very far from each other. But if you fold the paper in half, the two points are directly adjacent to each other, making the distance between them infinitesimal. So if space could be folded in such a way, you could travel between those two points almost instant. By the same theory, space-time could be folded, so you could travel between two different points in time in mere seconds.
The most obvious problem with this, is that you would have to build the wormhole first; people from the future could travel back in time to the origin of the wormhole, but no further back. People in the present wouldn’t be able to use it. So who would pay the money to build it? I’d warrant no corporation would invest in such a project.
Other wormhole theories abound. One such theory uses mathematics based on Einstein’s theories to form Schwarzschild wormholes, also known as Einstein–Rosen bridges. These wormholes would continue to last, and would allow travel both back in time, and forward in time. However, none have ever been found.
Traversable wormholes is a term to describe wormholes that craft or even people could travel through. (Some theories posit that communications could travel through wormholes, but the gravity of the mass would destroy living tissue). A traversable wormhole would allow states where negative energy to form a wormhole arbitrarily. This would have been formed during the Big Bang, and would continue to expand throughout time.
Graphic of wormhole travel, as envisioned by Les Bossinas for NASA, c 1998
So far it seems that the most logical (albeit unlikely and fantastical) theories that time travel is possible is cosmic string to slinghot forward in time, and traversable wormholes to go back in time. If we could find either phenomenon.
Any time machine that could be built is likely to be limited by cost. Who would pay for such a thing, especially given that people in the present may not even benefit from the machine?
Space.com
Nationalgeographic.com
Learning Mind.com
Wikipedia . com
Is Time Travel Even Possible?
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