As recently discussed, the generally accepted understanding of the far future of the universe is that we are living in a relatively short (a few trillion years) flash of light at the beginning of the universe, after which will come an inconceivable period of cold dark nuthin’. But there is another possibility based on some baffling observations: The Big Rip.
In short, it seems that the expansion of the universe is accelerating. Given what we know about how things work, the expansion should be slowing. The gravity from all the *stuff* in the universe should be slowing it down, at least a little bit… but it seems to be speeding up.
It is an observation without a good explanation right now. The mechanism behind it is not known; it is called “dark energy” simply because we don’t know what else to call it. But worse than simply accelerating, the possibility exists that the rate of acceleration is itself accelerating. One hypothesis is that there is a certain level of dark energy in the vacuum; this dark energy has an anti-gravitational effect. This hypothesis holds that the density of this energy per unit volume is constant over time, so as the universe expands, *more* of this energy is somehow added, increasing the total “pressure” shoving the universe apart. But worse still is the faint possibility that as the universe expands, the dark energy density actually increases. If this is the case, then as time goes by the force behind the expansion will grow asymptotically. *IF* this is the case, then at some point – somewhere in the vicinity of a few dozen billion years from now – the universe will essentially blow itself apart, down to and potentially including elementary particles.
If The Big Rip is our fate, the universe will reach its end *vastly* sooner than otherwise. The universe will end while the sky is still full of stars and galaxies, while terrestrial worlds still orbit nice warm stars.
YAAAAAY!!!