Ok, so, this is in the context of closed timelike curves. This is a thing which appears in the math of general relativity. It has never been observed in real life, and may disappear if we ever have a reconciliatian of quantum mechanics and gravity.

The study was a computer simulation of "what if we had some particles in a closed timelike curve and could mess with them", and there is no suggestion of this being applicable or even possible in the real world.

But how do they know they’ve changed the past because that past will be the established past. But then they’d try and change it again thinking they’d failed but then…oh no I’ve gone cross eyed.

Ok, I have a proposal to test the theory. I'll buy a lottery ticket the day before a drawing, then let's go back and change the numbers I picked. Even if it only works 25% of the time, I'm willing to buy 4 lottery tickets.

Well, that sounds completely insane. If that works outside of simulations, the first group to unlock it could take over the world. Or do whatever they want.

So the universe has rollback netcode?

There was a fascinating simple study done some years ago in regard to altering the past based on future actions. I will try to find it. But if I remember correctly, they had 2 groups of people, the control and experimental. Both groups were given the same list of words to look at briefly. I believe they may have then been distracted by an intervening task. Afterward, the individuals in both groups were asked to recall as many words as possible from that list. These results were collected, but not yet seen/scored by researchers. The experimental group was then given the original list of words, and were told to study them for awhile AFTER the recall test. Control group did not study. The recall test was then scored for both groups after the "study or not study" period. It was found that the participants in the experimental group that had the time to study the word list, (literally after the test was well over), scored significantly higher in those initial recall results! Lending to the idea that maybe we can influence past events in some manner that is measurable, eh?

The problem I'm going to assume applies here is the same as why we can't train self-driving cars with a simulation. It's a paradox; if the simulation was robust enough to train cars for the real world, then creation of the simulation itself WOULD be the solution since it already knows all the rules and correct reactions.

In other words, I'm sure they got their simulation to work, within the confines of a limited, non-paradoxical, error-prone programming.

its ability to achieve a form of backward time travel still shouldn’t necessarily be compared to a certain Flux Capacitor-equipped DeLorean built by a certain Doc Emmet Brown.

I am going to compare this to a certain Flux Capacitor-equipped DeLorean built by a certain Doc Emmet Brown.

I’ve seen this movie. This isn’t going to end well. If anyone needs me I’ll be in my basement preparing for a post apocalyptic hellscape.