What is the Big Rip?

"If dark energy is only a constant, than things like our Solar System, our galaxy, and even our local group of galaxies — consisting of the Milky Way, Andromeda, the Triangulum Galaxy, the Magellanic Clouds and a few dozen small, dwarf galaxies — will remain gravitationally bound together for trillions upon trillions of years into the future. But if dark energy is increasing, or getting stronger over time, then that acceleration rate will not only drive distant galaxies away from us, but will cause these structures to become gravitationally unbound as time goes on!"

Now that dark energy is firmly in place as the dominant source of energy in the Universe, the race is on to figure out exactly what its properties are, and what that will mean for the Universe’s fate. If it’s truly a cosmological constant, we’re in for a Big Freeze, as galaxies expand away from one another faster and faster, leaving only our gravitationally-bound local group behind. But if dark energy changes over time, we might yet see a Big Crunch or the most horrifying of all fates: a Big Rip, where galaxy-by-galaxy, star-by-star and eventually atom-by-atom, everything is torn apart!