(soothing music) - There are few questions
that grip our curiosity as vehemently as the story of us. Our civilization, our species,
even our tree of life. How did we come to be? Why are we the way we are? And how do we develop
and change over time? In a recurring dream, I see
myself walking down the aisles of a cosmic library, running
my hand over the books, chronicling the history
of the entire universe. Eventually, I stumble
across the book of us nestled away in some
forgotten dusty corner where few visitors come. The first chapter describes
our solar system's birth, the formation of the earth, the collision that forged the moon, the cooling of our planet, and the emergence of life. Flicking ahead by merely chapters, I finally come across humanity. If each chapter represented
100 million years, we wouldn't turn up until chapter 45. From humble beginnings
of microbes and muck, our bipedal homage ancestors worked together to hunt big game, develop tools and language
to aid their survival, and later, invent agriculture. Civilizations rise and fall, develops science,
literature, art, and war. And finally, the story reaches us. Now, here. This is what I'd been searching for. Just one more page to turn. But as I pull the paper
across, the dream ends. Each dream feels so close,
but the answer always escapes. What's so frustrating is
that we are by no means at the end of the story. If humanity arrives in chapter 45, then there should be
another nine or 10 chapters still ahead of us. One billion years, give or take, represents the current scientific estimate for the remaining time
that Earth can support complex life, such as ourselves. After that, the sun's growing luminosity will trigger an ecological collapse on a scale never before seen, as discussed in one of
our previous videos. But just think about that for a moment. A billion years left on the clock. Compared to our human lives, it's an unimaginably vast stretch of time. An immense abyss of countless moments, a haunting expanse that stretches out beyond ordinary understanding. A scale so vast that within
it, mountains will erode, stars will die, and galaxies collide. And yet, the universe plays a
cruel trick on our curiosity. For the unidirectional nature of time means that we are allowed to learn at least fragments of the story that has transpired thus far, but we are utterly forbidden from knowing anything that lies ahead. What happens to our fragile
attempt at civilization? How far do we go? How does the story end? We often think about human history in terms of centuries. Antiquity, perhaps, in terms of millennia, and evolution in terms
of millions of years. But a billion years? It dwarfs them all. Take the Neolithic Revolution. That is the beginnings of agriculture and animal domestication. Even if, somehow, our civilization was returned back to that point in some catastrophic reset,
that was just 12,000 years ago. In a billion years, they have enough time to repeat the entire
history of all civilizations another 80,000 times over. Over a billion years, we
have to talk about evolution. Microbes (*and viruses!) can mutate and evolve rapidly over a matter of months, as we all know from every flu season. But that's because
their reproductive cycle is so much faster than of ourselves. The humans' genetic drift occurs on a much longer time scale. Perhaps the best data comes from the split between Neanderthals and modern humans. About 2.5% of European DNA
comes from Neanderthals, which clearly indicates
some interbreeding happened. The fact that this is seen across Europe implies that sexual
relations were fairly common, but the fact that only
2.5% of DNA intermixed implies that it wasn't always successful. So Neanderthals and modern
humans may have been close to the limit of speciation, implying an evolutionary timescale of something like half a million years. Although, this is a number
debated by anthropologists. And so again, we are struck
by the enormous scale here. In the billion years ahead
of us, or 900 million years, to be a little bit more conservative, there is clearly sufficient time for humans to undergo
dramatic evolutionary changes, potentially splintering off into countless numbers
of evolutionary siblings. It's really difficult to articulate just how unrecognizable these distant descendants may be from us. One way to see it is to go
back in time a billion years. Then we're going back
before the dinosaurs, the Cambrian Explosion,
the emergence of animals, and even the emergence of plant life. Back then, the planet was dominated by single cell bacteria and archaea, and that's who our
common ancestors would be if we went a billion years into the past. And so, how unimaginably different could our future descendants be going a billion years into the future? Truly, we cannot make useful predictions about what these creatures would be like. Evolution just doesn't work like that, because all successful species are a product of adaptation
to their environment and mutual competition. And of course, there's always the prospect of a technological
species, such as ourselves, interfering with this process, causing mass extinctions,
selectively breeding new species, genetically tampering with existing life, or even introducing wholly new artificial lifeforms into the ecosphere. But would technological
species even persist? Perhaps humanity represents a brief and unusual
episode in Earth's history, where it finds itself
inhabited by such a species. Looking back into the past, the vast majority of Earth's history is indeed devoid of
technological civilizations. And so, perhaps too, that
is the fate of the future. And yet, for all of our failings and self-destructive tendencies, humanity has a compelling track record of not just surviving, but thriving through
global transformations and across the planetary surface itself. From pole to pole, and
desert to mountaintop, you will find people. We are an adaptable species. Our intellects us to devise solutions to problems using tools rather than having to wait for some new organ or appendage
to biologically evolve. And that has always been
our greatest advantage. And it's difficult to
imagine a circumstance where that survival edge
would ever be blunted. This current iteration
of civilization may fall. Indeed, that seems
inevitable to some degree, but the collapse of
society, or civilization is distinct from the
extinction of our species. You know, we often like to imagine that our superior intelligence makes us some kind of a gift to this planet, but perhaps we're more
like rats or cockroaches. We're not a gift, we're an infestation, and perhaps a very stubborn one that'll be difficult to ever fully expunge from the evolutionary tree. I've spoken of this before, but these ideas raise the possibility of persistent intelligence. If modern humans speciate many times over the next few million years, then our descendants will surely have a genetic predisposition
for intelligence. And if intelligence continues to offer survival and reproductive advantages, which seems quite probable, then intelligences of
some form or another, may very well inhabit our planet for a very extended period of
time, long after we're gone. Indeed, these intelligent species need not even necessarily
be our direct descendants, but perhaps the descendants of whales, dolphins, crows, or ravens, ready to fill the ecological
niche that we leave open after we're gone. Of course, that intelligence
may not even be biological, as humanity is in the throes of developing artificial intelligence that may soon compete
with that of our own. This discussion of how
intelligence emerges and reemerges is, of course, relevant to astronomers who hope to look out into the sky and answer the most basic
of questions, are we alone? Intelligence is not the same
thing as technology, of course. And already we know of
many intelligent species that co-inhabit the earth with us. So this is perhaps where our musings of the distant future become
their most speculative. For although we know of multiple instantiations of
intelligence amongst species, we only know of one species, that is us, that went on to develop technology. The Silurian hypothesis floats the idea that this may not be true, though. A fossil fuel hungry
technological species, such as ourselves, should have been viable as far back as 350 million years ago, and yet almost no trace of
them would be left behind. The rapid weathering
of the earth's surface means that anything beyond
about three million years ago would be almost totally lost. A definitive exception to this, though, would be space infrastructure, which of course is not subject
to the same weathering. And so, in the distant future, our descendants too might struggle to detect any signature of us. Our cities, our roads, and our monuments will have long eroded into dust. But, the Apollo 11 lunar descent stage will still be on the moon,
perhaps heavily damaged by eons of micro meteorites, but still surely recognizably artificial. And so, the fact that we don't see anything like this on the moon, at least besides what we put there, suggests that we may indeed
be the first, after all. At least the first space-faring species. I can't help but wonder what an Earth-based technological species, 300 million years from now, will make of those lunar descent stages. What their archeologists will infer from the twisted metal
heap incongruously adrift within the lunar desert. As many of you know, I
try to remain agnostic about the question of life and
intelligence in the universe. Everything we know about
the cosmos is compatible with us being alone. And yet equally, I'd be thrilled to discover evidence to the contrary. And yet, as pointedly, fiercely,
and consciously agnostic as I force myself to be on that question, for the sake of objectivity, I must admit to finding it difficult to doubt the possibility
that a technological species might reemerge on this
planet in the future, especially given its
starting point of today. But on the other hand, if many other technological
species emerge after us, then there is a certain coincidence that we happen to be
the first in this chain. Astronomers especially
are often more comfortable with being somewhere in
the middle of the pack via the famous mediocrity principle. But assuming, for a moment,
that this does occur, then there's a profound consequence. For even if that future species were of direct lineage to us, even if they were organically
a continuation of our society, the enormity of time that would transpire would surely culminate in a civilization that was essentially alien to us in almost every practical
sense of the word. And so, if we want to
communicate with aliens, I think we can. We just have to send a
message into the future. Not a message through space,
but a message through time. Like the lunar descent stages, we could leave something
behind for them to discover. A time capsule containing information about who we are, what we hope for them, perhaps even an AI that
they might converse with to learn about our society. And that message might patiently wait for 100 million years or more, before eventually being discovered by one, or even multiple
technological descendants. A whisper from the past. The tragedy is that we'll never see that moment for ourselves, like a grandparent who never gets to meet
their grandchildren, we may have to accept
an inevitable distance in that relationship. And we all feel this
in our lives as we age. A certain tragedy that we wish to know how our favorite team will
do in the next decade, whether humanity will ever
develop a certain technology, or what achievements our
family will accomplish after we are gone. All of them mysteries
that we have no choice but to go to the grave with. And in the same way, looking across much deeper swaths of time, humanity as a species may
have to accept the same fate. Our earth is a spectacular
terraqueous oasis of life within a stark and unforgiving cosmos. Its story may be one of many such worlds, or perhaps incredibly rare. In any case, our role
in this plant's history is already profound. And at chapter 45, we
can't help but wonder what those nine or 10
remaining chapters might hold. Perhaps a species will
blossom across the stars, or maybe the dawn of AI represents the demise of
curiosity on this world. Or perhaps we are doomed to a cycle of civilization rise and fall until the Earth dies. Or maybe we are the singular instantiation of technological life that
this planet will ever see. This isn't one of those videos where I can feed you the answers, only the questions. But what questions they are. Questions to fuel our
imagination, and our aspirations, and perhaps even influence
what we choose to do with the time that we have left. So until next time, stay
thoughtful and stay curious. (electronic music) Thank you so much for watching, everybody. I hope you enjoyed this video. If you did, be sure to
like, share, and subscribe, and if you really wanna help us out, then you become a donor
to my research team, the Cool Worlds Lab, just
like our latest supporter, that is Fritz Demopoulos. Thank you so much for your support, Fritz. Have an awesome day out there, and I'll see you in the next video. (electronic music)
