(I feel like this post is underappreciated by at least 20%. :D )
It probably will eventually stop, though. Something about the Sun becoming a red giant...
Not scientifically perpetual. But definitely, relative to the finite future lifetime of the human race, operable for perpetuity.
And by extracting dark energy, we can not only turn the big rip around. But by pulling dark energy out of space in a linear direction ahead of a ship, we can power the ship to high speed, as we contract space in front of the ship. Like fusion, we can use extracted dark energy to extract more dark energy. Essentially smoothly teleporting forward. No more fundamental speed limits relative to observers at distance. Looking forward to exploring beyond the observable universe.
It isn't "free" though. There are unique risks.
This will work in a sense. It will do… something… and learn… something. It will be unrelated to the physical universe in any way. See also: procedural landscape generators, etc.
Many decades ago, statisticians made a similar erroneous assumption that maximum likelihood estimators, which also minimize entropy, are "optimal" in terms of saturating error. The fact that you can do better by smarter regularisation is the key to why DL works in the first place.
I'm no shill for AI, but you're going to need a better argument for why runaway AI up to obscene levels of performance is not theoretically possible. There are quite a few people, including some of my colleagues, that are looking in earnest but so far no one has found one.