Let’s imagine a world where time machines are invented.
Hypothetically, what’s stopping anyone from travelling to the past, where the dollar is much more valuable, and buying things at a much lower price? What if you then go back to the present, sell those things at a higher price and repeat the cycle? And wtf would happen if everyone there started doing that?
Assuming the following conditions:
Energy is not conserved - that is, you expend less energy traveling to the past than the net energy value of something you send to or bring from the past.
It takes approximately 1 minute for the time machine to recharge and target a new time and location after use.
The time machine can transport any object that can be contained in a space, but the space is fairly easy to expand. Think, “setting up a tent”.
All of this, I should emphasize, horribly breaks physics. But it’s not a stupid question. The answer is, essentially, “the economy, as we know it, collapses.”
A lot of people are going to point out that you can duplicate energy sources, items, etc… by bringing them from the past. Yes, that’s true. But what people are missing is that this enables exponential growth as well:
I buy a gold coin. I put it in a large space.
2 minutes later, I set my time machine to go 1 minute back in time, collect the coin from myself, bring it to the present. Now I have 2 gold coins.
2 minutes later, I do this again - collecting the 2 gold coins and bringing them to the (new) present. Now I have 4 gold coins.
An hour later of doing this, I have over 536 million gold coins.
This works for any reasonably sized object, by the way. A hamburger. A tank of oil. That sweet RTX 5090 for your new gaming rig. A nuclear warhead.
Society, as we know it, isn’t to survive this. The Earth probably isn’t going to survive this. The universe may very well not, although we’ve already broken so many laws of physics getting to this point that it’s a wash anyway.
tl;dr - time machines as popular culture imagines them are a cheat code.
I don’t follow. If you took the coin from the past, it no longer exists in the present. You still have 1 coin. You are duplicated, however, and now two of you exist in the present timeline. You could do the duplication glitch by taking the present timeline coin back to the past and giving it to past self, who now has two coins.
This entire “glitch” is posited on the idea that altering your subjective past does not alter your absolute present.
And you’re right - that’s ridiculous. Why wouldn’t taking away something from the past alter the present? This is called causality and thermodynamics, and it’s one of the reasons physics, as we understand it presently, doesn’t really allow for time travel as it is popularly conceived. It’s not about gold coins, exactly, but the idea that you can’t end up with more energy than you started out with (or the mass equivalent of energy).
But OP started with the idea that a time machine which break causality and thermodymnamics exists, so I just pointed out how massively broken such a machine would be.
If I steal a gold coin from the year 2000, then, with that coin in hand, travel to 1999 and steal the same coin, I now have two copies. I then travel to 1998, 1997, et cetera, et cetera, on down the line, each time I gain an additional copy of the same coin. I then take all these coins with me to the present and spend them. Now just swap out the years for 2 minute intervals and you’ve got an infinite number of coins, or nearly so, anyway.