The Greek poet Hesiod described the Five Ages of Man in mythology.
They progress from the Golden Age, when people lived among the gods, through the warlike Bronze Age and on to the Heroic Age. His narrative ends with the Iron Age, a period of toil and misery for mankind.
Science has now replaced these mythologies. We are at the point where we look at the entire universe as a grand series of game-changing leaps toward our emergence as an intelligent species. It is an epic story more compelling than anything from creation mythology.
In a recent paper, Marcelo Gleiser of Dartmouth College describes the universe’s first three ages as the physical age, chemical age, and biological age. He says that we are now entering the cognitive age, the emergence of intelligence life on Earth and presumably across the universe.
This leaves us with an enticing question: what will be the fifth age of the universe? Will this be a period of decline toward the burnout of the last star, as our extrapolations from current astrophysics predict? Or could it be something more existential and unpredictable given the potential influence of “thinking matter” on the arrow of time? Are we entering a cosmological Age of Aquarius?
Advances in astronomy over the past several decades allow us to precisely retrace the four ages of the universe to the present. We are the first generation to know the geometry, material composition, and evolution of the universe.
Within only the past 50 years we have learned that life as we know it relies on chemical elements forged in dying heavy stars. The first stars formed perhaps as early as 200 million years after the Big Bang. They forge the heavy elements in a fireworks finale of supernova explosions. We are confident that chemically-enriched second generation stars went on to build a plethora of stable planetary systems.
Some fraction of planets became astrobiological “Petri dishes” for biochemical reactions. The hallmark of the biological era is the still unknown leap from dormant matter to self-replicating matter. This remarkable process is driven by complex molecular nanomachines storing and reprocessing information under Darwinian rules.
But is Gleiser’s cognitive era isolated to Earth? It presumes intelligent life could be co-emerging among the myriad stars and galaxies. At present it’s probably simplest to say that the vast gulf of time and space keeps us in cosmic isolation, if not quarantine, from fully answering this question.
This leads me to the idea of a fifth age for the universe, yet to be realized. Perhaps intelligent entities can evolve to have mastery over entire galaxies, as predicted by the Soviet Russian astronomer Nikolai Kardashev in 1964. He imagined that through extraordinary astroengineering projects, far advanced aliens might reshape a galaxy to their liking. They may tap energy off the galaxy’s central black hole and construct artificial habitats free of destruction from cosmic catastrophes.
But don’t go looking for Kardashev galaxies. They couldn’t exist yet. All of our deep space observations sweep us back in time to the earlier ages of the universe. Our most powerful observatories collect light that is billions of years old, allowing us a view into the distant past.
Along the way into this nameless fifth era, super-aliens might shed their physical bodies and abandon Darwinian evolution. This is not a new idea; it has been expressed by a number of science fiction authors including Arthur C. Clarke and Isaac Asimov.
In his 1956 short story, The Last Question, Asimov takes this idea to its logical extreme. Advanced “energy beings” fabricate a hyperdimensional super-computer that essentially reboots the unwinding universe. There is a second Big Bang when the computer asserts: “Let there be light!”. Call it a shaggy God story.
As far-fetched as this may seem, the alternative is frankly depressing. Perhaps extraterrestrial life flickers briefly and dies out across the galaxies because it is inherently unstable and self-destructive. Ironically even non-technological intelligent species are wiped out because they cannot build machines that might advert an astronomical Apocalypse, such as a renegade asteroid collision.
In either scenario we truly are alone. All we may ever find are electromagnetic and physical artifacts of long dead civilizations. This was nicely dramatized in James Gunn’s 1972 sci-fi novel, The Listeners.
There is undoubtedly some kind of fifth age to the universe on the far horizon. The universe will go on for at least another trillion years and perhaps infinitely longer. Making predictions beyond simple physics is impossible given such utterly unknown new phenomena as dark energy, which is now the ultimate force in the universe. Dark energy has the potential to rip the universe into shreds (though it seems stable by all measurements to date). Dark energy certainly could never be modified by the hand of a super-intelligence, other than perhaps God’s.
Image credit: NASA