All speculation on time travel end out in either paradoxes or infinities.
You are basically wasting your time, time travel is an impossible fantasy and not reality.
Time can be slowed, but there is no way it’s possible to travel back in time, because the past no longer exist. So there is nowhere to travel to.
In the same way the future does not exist yet, so you can’t “travel” to that either.
Time can however be somewhat suspended locally, so if you are suspended in time locally, it will appear as if you are traveling to the future. But in reality you are merely progressing in time faster at a slower pace locally.

If the many-worlds interpretation of quantum mechanics is true, it implies that everything that can happen will happen - or has already happened. If time travel is possible, this would include every possible outcome of you traveling to the past and altering events.

What I think would happen is that nothing would change in this timeline. Instead, you’d simply travel to another timeline where you made those changes, and you’d experience the consequences of your actions there. However, it’s also possible that such a scenario doesn’t align with the laws of physics, meaning that nothing would happen because time travel to the past - and any related interference - might simply be impossible.

I feel like just talking about the buying power of money or even the ability to effectively duplicate stuff is missing something: assuming your time travel actually allows you to change the past, and it doesn’t just end up in a situation where you can only fulfill a timeline that always existed, you can take technology to the past too.

Go back to the beginning of civilization and give them current technology (or even the beginning of time, and found a new civilization there). Then do it again (or if you don’t, someone else will eventually) with the new tech developed off the existing stuff over time. Repeated ad nauseum, you end up with a situation where civilization has and since the beginning has always had, every single technology it is physically possible to create.

You get the same kind of issues as “the singularity” (the concept where a super intelligent AI improves itself exponentially until it is as powerful as is possible to be). As such, our entire concept of markets and money and economy are likely completely obsolete, because find yourself in a universe populated by something as close as is physically possible to become to gods.

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.

Is energy being conserved? Because otherwise you would have an infinite energy source…

I think the most meaningful response is that effects on the economy wouldn’t be an issue because reality itself would break. Backward time travel would violate causality (cause and effect).

If you go back in time, even a microscopic alteration in events would lead to the universe being different than the one you came from in 2025, but how could you have come from the universe as it was in our 2025 if that universe never came to be because you changed how things would proceed when you visited the past?

You’d have to find the oldest bills you can find, time travel to the year they were issued, trade for older currency, time travel further back, and repeat until you’re at the point in time where the currency’s relative value is sufficient for your goals. So there’s that; it would be inefficient. I suppose you could travel with gold…

And rather than buying stuff, just put it in a bank you know would survive until present day and let it collect interest (or invest based on future knowledge, etc).

Arbitrage would iron out market inefficiencies across time as well as space.

If you are standing in your shower (shower thoughts) and try to travel 200 years back, your location in space is not where the solar system, nor the earth was 200 years ago. So there’s that…

Physics-wise, the only conceived ways to time travel to the past is either FTL travel or wormholes, with the latter requiring “exotic matter” to stabilize, and even then, you can’t go back to any arbitrary time. Nobody knows if exotic matter actually exists. FTL seems off the board.

There are mechanisms in place to keep history and the past safe for historians.

I think our global economy is safe.

There would be machines which produce energy in any form where source is future.

Essentially infinite energy solution. So humans would essentially have infinite energy but if you are allowed to go anywhere in time then why would you stay i ln present. You would immigrate (for lack of better word) to a time when is most suitable and to your liking. You would die in 80 years why do you want to spend time in current world time if you can do better.

It would become like a multiple reality world where like minded people would come together in same reality and people who disagree with them go to their own echo chambers. I belive most people would be looking for fundamental human desires like food, comfort and sex so people will go to time where they get it most easily.

So the easiest thing would be to buy cheap commodities that were expensive back then, go back in time and sell, then buy some kind of property or like shares in ibm. You could easily make a lot of money.

But you wouldn’t really be creating wealth, you would just be making it so you end up with it instead of someone else.

The best way to create wealth (assuming you can’t just create energy in the time travel process) is to take technology back.

Taking tech back (making a company with it so your rich too) would actually make humanity have a higher total wealth.

I personally would take solar cells and modern batteries back in time, might as well do some good with it.

Does everyone know that time travel exists? Or is it like a secret? If there was only one, whoever controlled it either way would be all powerful and immediate ruler of all people on Earth. There’s literally nothing you wouldn’t be able to do, and no force could stop you. Economics would be yours to control.

If everyone had access to time machines, it would be chaos. Markets literally would grind to a halt, because time travelers would be perpetually competing to be 1 second ahead of their competitors, all the way back to the beginning of time. Humanity would inevitably destroy itself.

weed probably end up with a small group of ultra wealthy controlling most of the world wealth

If that happens, I think the economy will suddenly always have been the least of our problems.