In this dark future, we might build enormous space power plants around black holes, lowering masses toward them to harvest their gravitational pull “like the weights pulling down in a grandfather’s clock,” says Princeton physicist J. Richard Gott. Or we might tap the internal heat of planets to generate energy: The gravitational interaction between celestial bodies creates friction, which can keep planets hot inside even without any starshine.
Don’t picture cave dwellers huddling around geothermal heaters. Trillions of years of evolution will have long since transformed us, Laughlin says. Perhaps we will have merged with our computers. Perhaps we won’t even have a physical form. The only thing our descendants will definitely have in common with us is the essential spark of life: not flesh and blood necessarily but information.
“That’s the most important lesson from thinking about the far future universe,” Laughlin says. “We’re being naïve when we think of life only in terms of Earthlike planets and carbon-based life.”
Information-based life can keep going almost forever. The gravitational era that begins around 15 trillion years from now could continue for quintillion years and beyond, Laughlin estimates. A quintillion is a 1 followed by 18 zeroes. It is trillion times as long as the entire history of our hominid line on Earth.
Will the universe die before we do?
Still, even this near-eternity is not the same as eternity. At some point, life runs into the physical limits of matter itself.
Physics theories suggest that sometime between 10^34 (1 decillion) and 10^64 (1 vigintillion) years from now, the protons found in the nuclei of all atoms will decay. That means black holes will be the only organized form of matter in the universe. Future humanity can’t have any physical form at this point.
At 10^100 years — 10 duotrigintillion years A.D. — even black holes will evaporate. There will be no energy or structures of any kind — just a cold, eternal mist of farflung particles. This really is the end point for life.
Or maybe not. Paul Steinhardt of Princeton University, one of the founders of modern cosmological theory, is exploring a model in which the universe goes through endless cycles of creation. His latest version, developed with Anna Ijjas of Columbia University, suggests that the universe could experience a new Big Bang well before the final black hole apocalypse.
If it does come, a new Big Bang would wipe away all traces of this universe — unless we can find a way to leapfrog into the next cosmic cycle. Current physics offers no guidance here.
Then again, we have quite a while to ponder the problem.
FOLLOW NBC NEWS MACH ON TWITTER, FACEBOOK, AND INSTAGRAM.