Because the universe is expanding at an ever-increasing rate,
[Physicists Lawrence Krauss and Robert J. Scherrer] calculate [that] in 100 billion years the only galaxies left visible in the sky will be the half-dozen or so bound together gravitationally into what is known as the Local Group, which is not expanding and in fact will probably merge into one starry ball.
Unable to see any galaxies flying away, those astronomers will not know the universe is expanding and will think instead that they are back in the static island universe of Einstein. [...] Observers in our "island universe" will be fundamentally incapable of determining the true nature of the universe.
From there the author jumps to a conclusion which made me think that science fact writers are a bit lacking in imagination compared to science fiction writers. :-)
It is hard to count all the ways in which this is sad. Forget the implied mortality of our species and everything it has or has not accomplished. If you are of a certain science fiction age, like me, you might have grown up with a vague notion of the evolution of the universe as a form of growing self-awareness: the universe coming to know itself, getting smarter and smarter, culminating in some grand understanding, commanding the power to engineer galaxies and redesign local spacetime.
If not for the line "all the ways in which this is sad", this paragraph would seem to indicate Dennis Overbye has read enough science fiction to be optimistic about the fate of the humankind and the universe. But then in the next paragraph he says:
Instead, we have the prospect of a million separate Sisyphean efforts with one species after another pushing the rock up the hill only to have it roll back down and be forgotten.
Wait, hasn't he read, for example, Charles Stross? Does he not know that long before 100 billion years are over, the humanity is destined to experience a technological singularity and transition to a post-human state, where (if they so wish) they will live in the forms of digital consciousnesses and travel through wormholes, thereby overcoming the light speed barrier? :-) But... since Dennis Overbye claims to be "of a certain science fiction age", maybe Charles Stross falls beyond his personal horizon. Perhaps the writers who came after the golden age of science fiction are as invisible to him as those distant galaxies that are flying away at the speed of light will be invisble to our successors. :-)
Otherwise, I would agree, the picture would be sad, if it's true that
As this universe expands and there is more space, there is more force pushing the galaxies outward faster and faster. As they approach the speed of light, the galaxies will approach a sort of horizon and simply vanish from view, as if they were falling into a black hole, their light shifted to infinitely long wavelengths and dimmed by their great speed. The most distant galaxies disappear first as the horizon slowly shrinks around us like a noose.
But really, I think that in a 100 billion years the humanity (though not in its present form, of course) will have both seeded the distant galaxies and mastered FTL communication.
Besides, why assume that our successors will have access to none of the knowledge the humanity has accumulated so far? Given how plentifully scientific knowledge is documented, there is a good chance it will survive for posterity.
And overall, how can you meaningfully speculate about what will happen a 100 billion years from now? For comparison, the current age of the universe is only 14 billion years. Most science fiction writers I know think you can't meaningfully speculate about the future beyond, let's say, 50 years from now. I don't know what is this "certain science fiction" age of which Dennis Overbye claims to be, but time seems to flow many orders of magnitude slower for him. :-)
Overall, though, he makes an interesting point. If you assume that the current astrophysical knowledge won't survive into distant future, then it's possible that, in the words of Dr. Krauss, quoted in this article, future cosmologists "will puzzle about why the visible universe seems to consist of six galaxies. [...] What is the significance of six? Hundreds of papers will be written on that." Moreover, the same thing may be happening today. Our physics and astrophysics research may be leading us down wrong paths because the evidence that would lead to right conclusions simply doesn't exist. Maybe we are already living too late to find critical evidence that would explain why the universe is the way it is. This aspect of the article is interesting. But the hand-wringing over the sad fate of future humans... gimme a break.