Everyone papers over these very real problems like they’ll just get solved. But if you can keep your ship at .05c while moving at .4c relative to your starting point that’ll be a huge deal.
Is there some data on this, or are you just making it up? It's long been a feature on one of the largest internet sites. I've never not had it work on the desktop, at least on Firefox, Brave, and Chromium on both Mac and Linux.
I just prefer not to presume when I link... .
The universe heat death theory makes me think of comics where people extrapolate the data they have while lacking other critical data. https://xkcd.com/605/
I think it's fair to assume that life will have practically zero impact on the universe. Even if the universe was teeming with it, it would be of such little significance at scale that it might as well be a rounding error in reality.
Think of a virus. A handful of specially shaped molecules has permanently changed human society.
Avoiding heat death requires a renewable source of negentropy, to bypass the second law. Some sort of perpetual motion machine that you can pump energy out of. E.g. if you could extract work out of the expansion of the universe fast enough to build expansion-work-extractors faster than they decay, and expansion continues indefinitely, then you can avoid heat death.
We can't predict what life will be doing in 100 years. What will it look like in 100,000,000 years of exponential growth?