An interesting and perhaps disheartening video illustrating the far, far distant fate of the universe. This covers timescales not of billions of years, not of trillions, but of trillions of trillions of trillions of trillions of trillions of trillions of trillions of trillions of trillions of trillions of trillions of trillions of years. In *very* short order – around a few hundred trillion years – there will be no objects left in the universe that resemble current stars. The universe will be vastly expanded, very dark and very cold; if you could time travel to a few hundred trillion years from now, there is no conceivable telescope that would be able to see the nearest galaxy, because the expansion of the universe would have driven it beyond the cosmic horizon. This would be an empty and hopeless time… and it would be the first tick on the clock of cosmic time. By far the vast majority of the lifespan of the universe will be spent in an era with nothing but the odd photon, the sole inhabitant of a volume of space larger by far than the now-observable universe.
Consider: a trillion years from now, the only stars still guttering along will be red dwarfs. The universe will be about a hundred times older than it currently is. Nearby galaxy groups will be measured not in terms of dozens of millions of light years, but in *billions* of light years. The Hubble can currently see galaxies that far away, but generally only as dim blobs. At that point in the future, those “nearby” galaxies will be old, red and quite dim; a Hubble of a trillion years hence would struggle to see them. By ten trillion years, the nearest galaxies would be about as far away as galaxies that today are on the cosmic horizon. If some planet somehow evolves intelligence, the sky would be so dark that it is very probable that the only stars in their sky would be a handful of red and white dwarfs scattered throughout their galaxy, the nearest perhaps a thousand light years away; it’s very likely that none of them would ever bother to build a telescope anywhere near as powerful as Hubble except, perhaps, to examine other planets orbiting their sad little star. They might spot those other red dwarfs and struggle to comprehend just what they’re seeing; if by chance they somehow task their one telescope with staring for *days* at a blank spot in the sky, the chances of them just happening to spot one of the rare “nearby” galaxies ten billion lightyears off – maybe a few dozen across the sky – is vanishingly low. And even then, they would still be existing at the very beginning of the universe.
This, my friends, seems to be a tad depressing. Contemplation of timescales like this and what they would contain is just that sort of thing likely to bring on some good old fashioned cosmic horror, because it shows that not only are *you* small, but the current observable universe is *microscopic* in terms of size and age in comparison to the enormity of the universe as a whole.
When Lovecraft and Co. were writing their weird fiction, their conception of the universe was trivially small compared to what we now understand. This sort of thing would, I think, have amused HPL and resulted in some interesting yarns.
One very, very hypothetical ray of hope is offered in the video. As some point in the inconceivably distant future, when our incomprehensible descendants are huddled for warmth and energy around decaying black holes, thinkigng one thought per trillion years, if they are smart enough and have access to the right resources, they could, perhaps, maybe, either open gateways into “parallel” universes, or make “baby” universes of their own, and escape to a whole different universe, there to perhaps watch *that* one slowly run down and escape again.