(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)