The scariest monsters Russell T. Davies came up with during his time as Doctor Who’s showrunner were the Toclafane. Essentially six billion flying metal spheres (each containing a wired-up human head), they were all that was left of humanity at the end of the universe in 100 trillion years. What made them so frightening was what they represented: the certainty that the universe would inevitably end, and the equally chilling certainty that humanity—desperate to stay alive at any cost—would inevitably lose all of its dignity, morality, and hope before it did. Like all great Doctor Who villains, the Toclafane exaggerate a human attribute; the Daleks caricature our desire to improve ourselves, the Cybermen our obsession with efficiency, and the Toclafane our fear of death. But will our descendants have to face the same horrifying end as the Toclafane?
Possibly not. Theoretical physicists suspect that at some point billions (but probably not trillions) of years from now, the universe will stretch, rip, or compress itself into something uninhabitable, but this suspicion is based on a number of very shaky hypotheses about what the universe really is, what dark matter and dark energy really are, and so forth. When we talk about how the universe will end, or what happened before the Big Bang, we are entering an area of physics that is so speculative that it may resemble theology more than it resembles physics as we generally understand it. This doesn’t mean that it isn’t work worth doing, but the study of First Things and Last Things is tricky and it’s unlikely that we’ve figured out all the details, absent most of the relevant evidence.
But assuming our understanding of the universe’s life cycle is basically correct, can we escape the end? Hypothetically speaking, yes, though not with our current level of technology. The obvious way of escaping the end of our universe, assuming our descendants know how, is to escape to a different universe entirely—much as we may need to escape our solar system before our Sun bites the dust in five or six billion years. The more creative alternative is to preserve the Sun, or indeed the universe itself, by some unknown means. I don’t pretend to know what those means might be—it’s impossible to reliably predict the state of technology in 50 years, never mind five billion—but it’s likely that these problems, or problems very similar to them, will need to be solved in some way. (Stephen Hawking’s recent suggestion that humans may one day have the power to manipulate the Higgs field certainly presents some intriguing possibilities.)
In other words, to answer the question I ask on the tin: we should take it as a matter of course that if we’re correct about the way the universe will end, our descendants will have a much more complete understanding of the problem than we do. While it demonstrates a kind of existential maturity to resign ourselves even at this early date to the certainty that escaping the end of the universe will be impossible, it isn’t especially rational. There’s still so much we don’t know—not only about the nature of the problem, but also about humanity’s capacity to solve it—and when we know so very little about what lies ahead, we may as well be optimistic.