- We have, through science over the last 400 years,
come to have a really deep understanding
of the natural world,
but so far that deep understanding doesn't include us.
(mysterious music)
It's really important in an age when we're being faced
with existential threats on a regular basis
to understand our place in the cosmos.
And I think unless we actually really address the question
of what is life, we're not really gonna understand ourselves
in the context of the systems that we live in.
Because we don't know what life is,
we don't know where in the universe to look for it.
My biggest worry is that
we might just completely miss discovering it
because we actually don't really have an idea
what we're looking for.
And we're thinking about the definitions of life
the wrong way.
(mysterious music continues)
I'm Sara Walker and I'm an astrobiologist.
What that means is that I'm really interested
in understanding if there's life elsewhere in the universe,
but I'm also really interested
in just understanding ourselves.
And so most of my work is really focused
on understanding the origin of life on Earth.
To do that, my group is building ensembles
of thousands or organisms and thousands of ecosystems
and looking at properties of their chemistry.
- On Earth, we're surrounded by life,
but we have no idea how common or rare living systems are
in the universe.
We have no idea how many different forms life can take,
no notion of what limits there are to its size
or the timescales it operates on.
We might've encountered alien life already
and not recognized it.
- There's this assumption that we make
that because we are alive,
we actually recognize life when we see it
or we understand what life is,
and I think that's actually a really flawed viewpoint.
For a long time, it was thought,
if we see oxygen in the atmosphere of an exoplanet,
that is a sign of life and we will be able
to claim victory that we have discovered aliens.
But (laughing) as scientists thought about it
a little bit more,
it turns out you can make atmospheric oxygen pretty easily
with simple models that don't even contain life.
We really need a more general definition for life
that doesn't depend on the specific chemistry
that life on Earth uses
but is more characteristic of what life is
as a process that organizes chemistry
and does all the wonderful things
that we associate with living matter.
So I, for example, have a very broad definition of life
that includes things like technology.
Part of the reason for that is,
if you found a phone on Mars,
you might not think that you discovered life,
but you certainly would think
you discovered evidence of life because the likelihood
of that phone being there is zero
without a living process putting it there.
Life is literally the physics of creativity.
It's the creative process in the universe.
It's not an individual in that process.
It's the entire process of,
how does information originate in the universe
and how does it expand through space and time
to construct all of the things that we associate with life?
(mysterious music)
- Most of the hazy definitions of life as we know it
are flawed because they're built
around a very small sample set of one,
the one living biosphere that we've evolved within.
- So anything that our technology creates
or we create or our subsequent generations will create
will be a part of our life or an example of our biosphere.
To really understand the possibilities for life,
we have to discover a second example somewhere else.
Because unless we get some constraints
on how likely life is,
I don't think we're really gonna fully understand
what life is.
- It's possible that our sample set will soon double
as we explore our solar system.
We could find evidence of life on Mars, Europa, Enceladus.
There was recently some indication of phosphines,
potential biomarkers, in the atmosphere of Venus.
Some of these places are hostile to life as we know it,
but they might be extremely welcoming to life
as we don't yet know it.
- So what I'm most interested in is trying to understand
whether there are universal laws
that describe living things much the same
as we have uncovered universal laws
that describe gravitation and if they're equally fundamental
and intrinsic to the structure of the reality
that we live in.
- Be defining gravity, Sir Isaac Newton put us on a path
towards mastering it,
a path that helped us understand tides,
the orbits of planets and comets, equinoxes,
and eventually helped humans navigate our solar system.
Having a definition of life will improve our chances
of finding extraterrestrials and could open our eyes
to a whole universe of possibilities
we can not yet imagine.
- It's hard to imagine what it's gonna be like
when we actually understand what we are.
All the technology we have doesn't include us
in our understanding of the world.
And then if you add that level of understanding us
and the technology we create,
then it's possible for humanity and our technology
to get to the next level, whatever that is,
that we can't even anticipate yet.
So a lot of the sort of deep understanding that I'm after,
I think, is critical for the longevity of life
and to expand our reach in the universe
beyond our own planet.
I think we take for granted how special we are.
We are a very odd kind of system to exist. (laughing)
I just can't imagine that an understanding of us
wouldn't radically reshape how we think about the universe
that we live in.
(mysterious music continues)
- To learn more about
challenging ideas
like this, visit us at Templeton.org/bigquestions