No, You Don’t Want to Time Travel
What’s forgotten when imagining time travel
The idea of time travel has long captured the human imagination. How many times in novels, movies, and TV shows have the plots involved characters traveling back in time? What an exciting thought to be able to witness events in the past or see what will happen in the future!
Time travel has been a staple of science fiction since its modern inception with H.G. Wells’s The Time Machine. It is overused now as a plot device, but the dramatic possibilities of time travel intrigue both writers and audiences.
Fiction is not reality, and just because we can imagine doing something doesn’t make it possible. Physicists debate whether it is possible to travel through time. Some say it is possible even provably so. Others say it is not possible.
The physicists’ conjectures, and they are all just conjecturing, are based on complex and obscure discussions of relativity, spacetime, the massive energy required, and whether time exists as something real outside of human perception.
These conjectures and discussions grapple with deep and meaningful issues, They do, however, ignore one simple reality that is very much not conjecture: time travel is a very bad idea. Very, very bad.
Time to Think about What Really Would Happen
So, let’s say that you, being the genius that you are, have solved the physics problems of traveling through time. You have invented and built a time machine and are eager to use it. Sounds great, yes?
Before you start your career as a chronic argonaut, you should remember one very important fact. Even if time is the fourth dimension, you cannot forget about the first three dimensions. Moving through time also means moving through space. Let me explain.
The first problem with your time travel is that Earth rotates on its axis. A spot on the Earth’s equator is rotating at 1,674.4 km/h. Other locations on the planet are rotating at a slower speed, as figured out by those kids who paid attention in trigonometry class and are indicated in this graphic.
If you could stand still in three-dimensional space, the Earth’s surface would be speeding past you faster than a commercial jet. That includes the location from which you start off in your time machine. When you are on the Earth’s surface, you are sped along with it. Ask the physicists how that works, that can explain. If you time travel, you are detaching yourself from the movement of the Earth’s surface.
So, if you launched your time machine from Cape Canaveral and set the clock for one hour in the future, you’d end up near the west coast of Mexico. The further you move in time the further your initial location on the Earth’s surface is moving away.
All right, you say, you can solve that problem by moving your time machine to one of the poles which the math indicates has little to no rotation tangential speed. You have a warm coat, you’re good.
True, your rotation speed is close to zero, and you won’t end up somewhere else on the surface because of Earth’s rotation. Or here’s a better idea, from anywhere on the globe you can calculate your time jump to the exact second so that you emerge at the exact same time on a day in the past or future. The Earth will have rotated one full circle, and you will be right back to where you started, right?
Sorry, no, rotation is only one movement happening to the Earth. The Earth also travels around the Sun at an incredible speed. The orbital speed of Earth is 29.78 km/s or 107,200 km/hr. So, if you launched your time machine one hour into either the past or the future, you’d arrive up to 107,200 away from Earth, which is three times farther than geosynchronous orbit. Suffice it to say, your exploration possibilities in your new time and place would be limited.
Oh, and don’t think you can time it so that you reach the same second of the same day each year and end up on the same spot on the Earth in its orbit. The whole solar system orbits the center of the Milky Way galaxy at around an estimated 500,000 km/hr. Just one hour of moving 500,000 kilometers is a distance much greater than the Earth’s distance to the moon.
Even if you learn how to move through time, you won’t be able to set the machine and emerge in a different time within the same room you left. You will end up somewhere in cold dark space and die pretty quickly. Only if your starting and ending point were at the same stationary point in space would time travel be simple. And only one tiny group of people believe such a thing exists.
Only a Flat-Earther Would Want to Time Travel
The only people who would consider time travel a feasible pursuit are those who ignore reality and believe the Earth is flat and motionless. There are, strangely, a few people who still believe that, as I discussed in my previous article. Search YouTube for “flat Earth” and find some hilarious videos about flawed science experiments and bizarre conspiracy theories.
The flat Earthers aren’t smart enough to figure out the physics of time travel, but if they did, they too would end up somewhere in cold dark space and die pretty quickly. Only a flat Earther would be foolish enough to try to time travel. It would be their last action.
Maybe This Is a Good Thing
Sure, it is such a cool idea to imagine being able to go back in time. But maybe it is good that it is impossible, or at least a very bad idea. If time travel was as fiction imagines it, we would be inundated by people from other times visiting us.
Great historical events would have thousands of people crowded around trying to attend. Famous people would have time travelers constantly showing up wanting to talk to them. It would be chaos. So, not just in terms of physics, but in terms of social order, time travel is a very, very bad idea.
An interesting article on the science of time travel: Is Time Travel Possible?
Also, the Z axis thing, where even if you could set off from cape Canaveral to arrive on the west coast of Mexico, you'd either be deep inside the earth, high up in the air or find yourself orbiting the earth. I imagine that even if they could solve all of the impossible problems, why would anyone want to go back to the days before Adventure Time, with terrible computers running really slow internet? To paraphrase LP Hartley, the past is another country- close our borders now!
I'm sorry to say this doesn't move me! These kind of gotcha explanations of fiction never engage with the actual premise.
All position in space and motion is relative to some frame of reference. What you're doing here is imagining the time traveller unmooring themselves from it all. But there is no absolute frame of reference, and even if there was, no science fiction author is imagining the time machine working that way. There are two common time travel machine concepts:
1. The machine moves between fixed points in space-time relative to the Earth (e.g. it appears to emerge in the same location each time).
2. The machine is also a teleporter and can move to any point in space and time (ancient Egypt, revolutionary America, Napoleonic France etc.).