Earlier quoted context omitted.
I wonder if any sentient being would really want to live forever. What would there be to look forward to as the galaxies recede out past the cosmic horizon and all the stars shutdown? What would be the point? Just wait around in the dark until the heat death gets you? I sometimes suspect that simple nihilism is the answer to the Fermi Paradox.
With all the compute and energy available at that stage, perhaps there are more possibilities than we can currently see or imagine? I sometimes like to think that we ourselves are actually the memories of a distant descendant. Maybe it reversed the light cone and was able to replay everything with exacting precision. Maybe it's studying and musing over its humble beginnings. (It might get a laugh that we're communica…
It seems like a long time since there have been any really game-changing breakthroughs in theoretical physics. I'd be a fool to say that that means that there aren't any more to be had, but it does seem more like we're just sort of fiddling around with a few refinements and there might not be anything huge left. As you say, maybe a greater intelligence than what we've got can figure it out, but that does go back to Fermi - if they could do amazing things like enclose a star or travel interstellar distances, then why haven't we seen them?
What if it's all just protons, neutrons, and electrons (and some other less important particles presumably) plus a bunch of energy out there? Would a super-intelligence really be interested in seeing more of them?