Katie Mack The death of the universe and what it means for life TED Fellows
[SHAPE YOUR FUTURE]
I love the universe.
The vastness, the mystery,
the astonishing beauty of the stars.
I love everything about it,
and I’ve devoted my life to studying it.
From atoms to galaxies,
from beginning to end.
But lately, I’ve gotten stuck
on that last bit.
The fact that the universe is dying.
I know this may come as a shock.
I mean, it’s the universe,
it’s everything.
It’s supposed to be eternal, right?
But it isn’t.
We know the universe had a beginning
and everything that begins ends.
The start of the story is a familiar one.
In the beginning, there was light.
We know that because we
can see it directly.
The cosmos today is filled
with low-energy background radiation
left over from a time
when the whole universe
was an all-encompassing inferno.
In its first 380,000 years,
space wasn’t cold or dark.
It was thick with a churning,
humming plasma.
It was hot and dense.
It was loud.
But it was also expanding.
Over time, the fire dissipated
and space cooled.
Clouds of gas pulled together
by their own gravity
formed stars and galaxies
and planets and us.
And one day,
astronomers using a microwave
receiver detected a bit of static
coming from every direction in the sky,
the leftover radiation
from that primordial fire.
We can now map out the cosmos
to the farthest reaches
of the observable universe.
We can see distant galaxies
whose light has taken
billions of years to reach us.
So by looking at them,
we are looking deep into the past.
We can watch how the expansion
of the universe has slowed down
since that hot early phase
13.8 billion years ago.
We can see collisions of entire galaxies
and watch the bursts of star formation,
that result from the sudden conflagration
of all that cosmic hydrogen.
And we can see that these collisions
are happening less and less.
The expansion of the universe
isn’t slowing down anymore.
A few billion years ago,
it started speeding up.
Distant galaxies are getting farther apart
faster and faster.
Star formation has slowed.
In fact, we can calculate
exactly how much.
And when we do,
we find something shocking.
Of all the stars that have ever been born
or that ever will be,
around 90 percent
have already come into being.
From now until the end of time,
the universe is working on just
that last 10 percent.
The end of the universe is coming.
There are a few ways it could happen,
but the most likely
is called the heat death,
and it’s an agonizing,
slow languishing of the cosmos.
Stars burn out and leave smoldering ash.
Galaxies become increasingly isolated
in their own dim pools of light.
Particles decay.
Even black holes evaporate into the void.
Of course, we still have some time.
The heat death is so far in the future,
we hardly have words to describe it.
Long past a billion years,
when the sun expands
and boils off the oceans of the Earth.
Long past 100 billion years,
when we lose the ability
to see distant galaxies
and that faint trace of Big Bang light.
Long after we are left alone
in the darkness
watching the Milky Way fade.
It’s OK to be sad about it,
even if it is trillions
of years in the future.
No one wants to think about something
they love coming to an end.
As disconnected as it may be
to us here and now,
it is somehow more profound
than personal death.
We have strategies for accepting
the inevitability of that.
After all, we tell ourselves,
something of us will live on.
Maybe it will be our great works.
Maybe it will be our children,
carrying on our genetic material
or perhaps our basic outlook on life.
Maybe it will be some idea
worth spreading.
Humanity might venture out
into the stars and evolve and change,
but something of us will survive.
But if the universe ends,
at some point we have no legacy.
There will come a time when,
in a very real sense,
our existence will not have mattered.
The slate will be wiped clean completely.
Why should we spend our lives
seeking answers to the ultimate
questions of reality
if eventually there will be
no one left to tell?
Why build a sandcastle when you can see
that the tide is coming in?
I’ve asked a dozen other cosmologists
and they all had different answers.
To some, the death of the cosmos
just seems right.
It’s freeing to know
that we are temporary.
“I very much like
our blipness,” one told me.
To others, the question itself motivates
the search for some alternative theory.
There must be some way to carry on.
The slow fade to black
just cannot be how our story ends.
One found comfort in the possibility
of the multiverse.
“It’s not all about us,” he said.
Personally, I feel lucky.
Our cosmos existed
for billions of years before us
and it will carry on
long after we are gone.
For this brief moment, we are here.
We may be insignificant
to the cosmos as a whole,
but we have an immense power
to understand it,
to see the beginning,
to contemplate the end,
to look up into the sky
and see ourselves reflected
in every tiny point of light.
There is a kind of luxury in the freedom
to look beyond our own little lives
and contemplate the end of everything.
We, fragile, doomed humans
carry within us a sense
of discovery and wonder.
It will persist as long as there are
thinking beings in the cosmos.
And we can decide how to use it.
Thank you.