Why a Time Machine Would Instantly Kill You
A short lesson on Earth's movement through space
You could finally meet all your deadlines, give your kindergarten bully a wedgie, and make out with your younger self. But don’t get too excited just yet. Time machines have one serious problem — they’d kill you. Instantly.
Here, let me explain why.
Our planet is moving faster than you think
Lovely, isn’t it? How our planet is sitting there, suspended in space, gently spinning around its axis, bringing us day and night as the sun shines on one side and then the other. Such tranquility. Such calm.
But the picture is misleading. Maybe a better illustration would be this:
Okay, that isn’t accurate either. But it conveys something the first image doesn’t. You see, although from space Earth seems to be spinning gently, in reality it isn’t. Not at all.
Yes, a day lasts 24 hours and that’s the time it takes for our planet to complete a full rotation. But Earth is enormous. It’s not a pebble. It has a circumference of 40,075 kilometers (~ 25,000 miles) and a radius of 6,371.0 kilometers (~4,000 miles). This means that a point on the surface of the planet is moving at insane speeds.
If you don’t understand why, look at the following animation:
Both the red and the green ball have the same angular velocity, that is, they take the same amount of time to swipe out the same angle. But the tangential velocity is not the same. The green ball is moving through space much faster than the red one. And that’s even though the two balls are just an inch away from each other. Imagine how much faster the green ball would move if it was ten inches away from the red ball. Or how about 200 inches? Now imagine how mind-bogglingly fast the green ball would go if it was 253,440,000 inches away.
That last number corresponds to 4,000 miles and is approximately the radius of the Earth.
You know what that means? It means you are the green ball at a distance of 4,000 miles from the center of rotation. Even if the red and blue ball are taking a whole 24 hours to complete a turn, as the Earth does, you are still speeding by at an insane 460 meters per second or almost 1,000 miles per hour. You just don’t notice it because the ground under you, the atmosphere, and everything else around you also moves at that speed.
It’s like when you’re sitting in an airplane and a flight attendant hands you a packet of peanuts. If you open it and then pop a peanut into your mouth, you don’t die of a headshot. Even though the peanut is moving at a speed of several hundred miles per hour, it harmlessly enters your mouth because you are moving at about the same speed.
Moreover, our planet is not only rotating around its axis, but it’s orbiting around the sun and it’s doing so at a speed of nearly 30 kilometers per second, or, roughly, 67,000 miles per hour.
Yes, it takes our planet a whole year to complete an orbit. But that doesn’t mean it moves slowly. It just means that it covers an enormous distance.
Why time travelers need to care about Earth’s movement
Don’t you see the problem yet?
Okay, let’s suppose you have a time machine. Something that looks like a telephone booth. It has some knobs and buttons that allow you to specify a precise date in the past or future. So, wanting to see a real T-Rex, you…
Actually, maybe we should try something safer first. How about we only move one minute into the past? Just to make sure the whole contraption works.
So, you enter your time machine, twist a knob to travel to T-minus one minute, and press go. What would happen next?
Answer: You’d die. You’d turn into “an inflated goatskin bag” and gas would be expelled from your bowels and stomach causing “simultaneous defecation, projectile vomiting, and urination.”
Huh? Why would that happen?
Here’s why: Because the Earth travels around the sun at 30 kilometers per second. So, in one minute it would travel 30 * 60 = 1,800 kilometers or 1,118 miles. That’s about 4.5 times the altitude of the International Space Station. Thus, as time is rewinded while you’re standing in your phone booth, the Earth would zip away under you. You’d end up in the middle of space and one of the side effects of being suspended in a vacuum is the goatskin, vomit, and pooping horror quoted above.
What if the time machine also moves through space?
If you not only travel through time, but also through space, then your time machine may begin to be useful. However, it would still be extremely dangerous.
Let’s assume you’d travel back 1,000 years into the past. Where exactly in the universe was our Earth so long ago? You would have to know and you would have to know very precisely. The smallest error and you’d end up in space again or, which is not much better, you’d transport yourself into the Earth’s crust, into the middle of a mountain, or somewhere in the middle of the atmosphere.
Moreover, even if you knew precisely where our planet was at your destination time and you were able to transport yourself there, you don’t know what exactly was at that location in the past. A brontosaurus might have been standing there and — whoops — suddenly you’re materializing as a dino’s butt plug.
And even if you could make sure that there’s nothing standing at your destination, you still have another problem — you need to match the Earth’s speed and direction. In other words, you have to match its velocity. Otherwise, considering how fast the Earth moves, it’s like trying to board an incoming bullet train.
And please note that to avoid being whacked like a mosquito by planet Earth, you also need to consider how the sun and the whole solar system are whizzing through the galaxy.
Here, look at this:
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That’s our solar system moving through space. The yellow ball is the sun and the light blue ball going round and round making a corkscrew movement is the Earth. To survive using your time machine, you need to safely land on that crazy swirling ball.
So, as you can see, a time machine would almost certainly kill you. The only way it wouldn’t is if it also transports you through space with the uttermost precision, makes sure you don’t materialize within a dinosaur or some other obstacle, and accelerates you in the right direction to match the Earth’s velocity. Considering all that, it doesn’t seem worth the risk, no matter how much you’d like to give your kindergarten bully a wedgie.
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