I just realized I haven’t yet told all of you about my ultimate plans for Earth in the far future of my space opera setting! In my post “Taking my Space Opera Setting into the Extremely Far Future”, I left them ambiguous, but now I’ve got a fairly definite idea of what I want to do with the mother planet. In that post I explored the idea of a story consisting of vignettes following what happens on Earth:
- Millions of years, perhaps 10 million years, into the future, when man has become a mature spacefaring civilization
- Tens of millions of years after that, when man has disappeared from the scene and the now once again wild Earth is settled by a new race of alien colonists who discover a cryptic artifact from the previous inhabitants.
- 250-350 million years from now, when a group of alien explorers indigenous to an ice planet visit the new supercontinent of Amasia near the equator of what’s at this point a snowball Earth, viewing a solar eclipse near the equator amid a ground blizzard.
- 500-800 million years from now, when Earth is a hothouse desert world dominated by flying animals and carnivorous plants.
- Some vignettes perhaps covering the Sun’s expansion, the extinction of complex life on Earth, and its collision with Mercury and ejection from the solar system within 3 billion years or so from now.
As a rogue planet, Earth escapes the fate of being swallowed up by the red-giant sun, careening about in the endless blackness of interstellar space for eons, occasionally colliding with other rogue bodies in the now-giant-elliptical galaxy (Milky Way and Andromeda will collide in just a few billion years), no doubt accreting mass over such an extended timespan.
A Last Candle in the Eternal Darkness
The universe as we know it, with stars dying and new ones forming to take their place, lasts for about 100 trillion years, but after that time free hydrogen becomes so scarce few new stars form, leading to all the red dwarfs becoming white dwarfs, winding down to black dwarfs, leaving the universe a very cold and dark place. All is not lost, though; brown dwarfs are still around, and collisions between them will keep a hundred or so lights burning in the galaxy indefinitely.
By 100 quintillion years from now “dynamical relaxation” causes most stars and objects to be ejected from the galaxy, which by this point has been nigh pitch-black for eons. Further dynamical relaxation makes what’s left of the galaxy more and more dense and compact, leading to the galaxy’s remaining mass falling into the central supermassive black hole by 1030 years from now. The last gasp of the universe as we know it occurs at this time, as the in-falling mass lights up an accretion disk and jets for a few billion years, shining upon a vast volume of space in an echo of the quasars so common eons earlier in the universe’s history.
Here’s where it gets fancy: Earth has been a rogue planet traipsing through the galaxy for all those eons, and in my story it happens Earth is right at the position about the quasar for liquid water and life as we know it to exist at the surface. Life begins anew under a very different sun from Earth’s original.
The Lastborn of Mother Earth
Unlike the firstborn of the mother planet, the lastborn will see only one bright source of light in the entire night sky: the great quasar, the rest of the celestial sphere being an inky blackness punctured only by the occasional Type 1a supernova. I’m thinking a new intelligence will arise, but one more exotic than any possibility I’ve hitherto explored, which seems appropriate: a sessile species, resembling flowers, with Earth of this age covered in giant beautiful vivid flowers, telepathically linked in a vast plant computer network, sending out spores to colonize the cosmos. Their culture emphasizing light and candles, strings of lights, with bright airiness being everywhere, as if the spirit of life is making some defiant last stand against the sublime darkness of eternity.
They form a spacefaring civilization surrounding the quasar, discover wormhole technology, and in the fullness of time ascend to a higher plane of existence just like the first race to arise on their world did: humans, who called the planet Earth. Ultimately Earth’s fate is to, along with the rest of the galaxy’s remnants, spiral into the accretion disk, be torn apart, and become part of the central supermassive black hole. Talk about a blaze of glory! Sorry, fans of the red giant sun, but a supermassive black hole at the end of the universe is a whole new level of cool; if Earth is to be swallowed up by anything it should be that.
As for the flower people, I’m thinking they evolved intelligence as an adaptation to the harsh and variable radiation levels; knowing when to hide or protect yourself is useful, plus the same radiation provides abundant energy to feed a brain (really more of a network). The telepathic connections enable them to use the whole planet Earth as a gravitational wave detector, allowing them to see the full galaxy in its pitch-black splendor despite almost all of it bar the quasar being dark to light as we know it. These very sensitive detections will aid them in their efforts to travel the cosmos via sending out spores, precisely flicked out of the planet’s biosphere to land on suitable planets elsewhere, their imperative being to wake up the cosmos around the great god-like light in their sky.
At the grand finale of Earth’s journey, it’ll be something like “Until at long last they too, the youngest daughters of Earth, had ascended, taking their biosphere with them, leaving the mother planet to its fate: spiraling into the black hole in one final blaze of glory.”
Sublime Fates
Even the black holes will die. Maybe. Hawking radiation should take all the black holes within a googol years or so, but as John Baez points out at this fascinating page what’s often not appreciated is that black holes only evaporate when they’re warmer than the cosmic background radiation; all of the really big ones are now colder than the cosmic background, meaning they’re actually gaining energy from it and accreting in mass!
The expansion of the universe will eventually bring the cosmic background radiation to a minimum of 10-30 kelvin (freakily, the cosmic background is an event horizon itself, and thus emits Hawking radiation, meaning it will never go below that temperature), much colder than any known black holes today, so they should all start to evaporate and lose mass.
Unless a black hole can grow to 1022 solar masses or greater, in which case its Hawking temperature is below 10-30 kelvin, and it keeps absorbing thermal radiation from the cosmic background and grows forever. No heat death of the universe: just an ever-growing energy gradient, which intelligent beings like ourselves could harvest forever. As Lee Smolin points out in his critique of the heat-death concept:
It has long been known that gravity is important for keeping the universe out of thermal equilibrium. Gravitationally bound systems have negative specific heat—that is, the velocities of their components increase when energy is removed. … Such a system does not evolve toward a homogeneous equilibrium state. Instead it becomes increasingly structured and heterogeneous as it fragments into subsystems.
In such a sublime future as what I outline, gravity has prevailed in its tendency to concentrate. The reason we don’t hear about this possibility much is that 1022 solar masses is a huge size for a black hole: that figure is within one order of magnitude of the total mass of the observable universe, but taking into account the dark matter it only comes to 1% of the total. Still unlikely, but the formation of such an object can’t be completely ruled out; in some other parts of the universe far beyond where we can observe it might even be likely!
Toward the End of Time
But I think I’ll ignore this possibility in my story, since after Earth spirals into the black hole the matter is still there but it’s not really Earth anymore, in the sense of being a planetary object. So the tale of Earth’s journey will end there, leading to the coda:
The final vignette will be when the universe winds down completely into heat death, the Big Freeze, and we see a child being called away from his parents right after his little mind loses interest in the universe he’s become gravity in, whining that it’s now cold and dark and winked out and he was having so much fun with it, with the dark fluid, and the gravity, and all the forces being so fine-tuned, it was so much fun while it lasted.
His parents will appear as immaterial spirits, take on human form, telling him becoming gravity in their universe of origin was a very wholesome endeavor for a boy (apparently with it being some difficulty just to interact at all in the lower realms of existence in any meaningful way; it’s something a godling must learn), and pointing out to him that he can learn about how to become some other force instead for the time being.
They reassure him that “you’re human; you’re timeless” (revealing that these god-like entities are the humans who ascended), and that a new Big Bang will come around in that realm of existence before he knows it. The atmosphere here is a kind of divine detachment from how we mortals understand time. He exits our universe, tosses it aside, and the cold dark realm of existence waits on the metaphorical shelf until a new Big Bang will arise and existence as lower life-forms know it will begin anew.
I’m thinking our universe will be something like a marble he tosses on the shelf, or perhaps a bubble that floats around in the endless airy breezes of heaven, the endless cold darkness to us being but a little while to them, being far beyond our mortal understanding of time. Well, not so fast. In 10^10^10^56 years, quantum effects may have had time to recycle the cosmos enough to create a new Big Bang, bringing a universe like our own into being, and existence can begin again. At least that’s what Wikipedia says.
Roger Penrose has an interesting theory, Conformal Cyclic Cosmology, positing that everything ultimately decays into radiation, and since photons are massless particles that travel at the speed of light, distance and time would have no meaning in such a universe, making its end the equivalent of an infinitely dense infinitely small infinitely hot Big Bang singularity! The universe could begin anew that way. Personally I think it’s an elegant idea, but I’m not sure I wish to canonize it within my space opera; there’s no need for the gods at the end to go into that much detail, only to make it clear to the boy that a new Big Bang will arise, so I’m thinking I’ll keep it ambiguous anyway. Why not, since it’s the most mind-screw-y thing I’ve thought of yet?
Conclusion
That’s about all the new material I have to add for this idea. The more I think about it the more I want to actually write this story, but I’m not sure exactly when; I’ve got other things going on in my life now and I’m not really motivated to sit down every day and write whole novels like I used to, but lately I have been putting out a short story or novella every month and I’ve been enjoying that format. We’ll see