Nevermind whether you could or not, what would happen if you did go back in time? What would happen if you could build an actual, functioning time machine?
Let’s say you were sitting inside this time machine right now.
Let’s also say that, for whatever reason, there’s a small table with wine classes on it inside the time machine.
Let’s pretend we knock one of these wine glasses over. This glass is now tumbling to the ground. As it’s midair, we turn on the time machine and go backwards in time.
What happens to the glass?
Does the glass:
- Continue to tumble to the ground because it’s inside the time machine, OR,
- “Rewind” back to the top of the table?
Each requires looking at time travel in very different ways.
The Glass Continues to Fall
The only way for the glass to continue to fall to the ground is if everything inside the time machine is still moving forward in time while the time machine, itself, moves backward in time.
That means you’re not really “going back in time.” You’re going forward in time. The time machine is taking you to an earlier point on history’s timeline.
That can happen two different ways:
- You leave the universe and reenter at an earlier point.
- You travel from Time A to Time B the same way you’d travel from London to Paris.
I’m not even going to touch how you’d pull off the first one.
The second one, though? If you can travel in time the way you can travel in space, you just might go back in time to find nothing there.
I don’t mean the Earth will be in a different place because it’s hurtling around the sun, I mean the Earth won’t be there because the Earth has already traveled from Time A to Time B – from the past into the present.
If you get on a plane from London to Paris, there isn’t another you still in London. You’ve left London. You’re somewhere else now.
Similarly, the Earth will no longer just be hanging out in the past, still. If time travel works the same way as space travel, then you, your friends, historical figures, the Earth, the sun, and…….. the universe? can likely only exist in one time as well as in one place.
One place at a time. One time at a place.
(P.S. quantum elements can exist in more than one place at a time, but entire planets are another matter. Probably).
The Falling Glass Rewinds
If the glass doesn’t continue to fall to the ground, but rewinds, then you’re going back in time.
That means that you are also rewinding.
Everything outside the time machine is going backwards. The glass is going backwards. Your actions are going backwards. Your memory is going backwards.
So, what really happens is that you turn the time machine on, which rewinds you back to a time when the time machine was off.
And then you’d turn the time machine back on again…
Which is kind of hilarious because you’d just keep doing that.