Can Life Really Be Explained By Physics? (featuring Prof. Brian Cox) (1)
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I think that life is the most fascinating, naturallyoccurring phenomenon in the universe,
and I think that's uncontroversial. I mean clearly, the human brain is the
most complex structure that we know of. It is a product of the laws of nature,
but we are a long way from understanding how that produces the experience of living right. And so
really, if you wanna ask what's the meaning of life, then first of all, we need to understand
life, and secondly, we understand consciousness 'cause meaning emerges from consciousness.
I think it's a little unfair that everything sounds so much better with your accent as you
explain things about the origin of the universe and origin of life. It's a little unfair.
So, are you saying that it's not the
inherent poetry in my construction of sentences or the conveying of ideas, it's just the accent?
60/40, we'll call it 60/40. We'll go with that.
60/40, I'll take that.
I recently sat down with Science Communicator,
Brian Cox. Now, he's a physicist, but our conversation didn't focus on the Big Bang, or
alien worlds, the strangeness of black holes, or any of that stuff. We talked about what it means
to be alive. Now, life is one of those things where... well, you know it when you see it, right?
But what is it exactly, that makes me different from a rock?
So maybe by looking to physics and asking some questions about the fundamental rules of the
universe, we can understand the meaning of life. Like literally. Really, really?
Hey smart people, Joe here. Y'all might know this already, but I'm a biologist, a doctor of
the biological sciences to be exact. So why would I need to call up a physicist to talk about life?
Well, next to why are we here? And where is here? What is life? Is one of the biggest questions out
there. And it's one that people have asked in various ways since people have existed.
But in every era before today, it's typically involved a supernatural answer. It's a very
new idea, just in the past couple of centuries, to look only to nature for the answer instead.
And one of the things that inspired this change in perspective was the dawn of modern physics. Every
living thing that has ever existed is a product of the universe. And every process in the universe,
from the swirling of the galaxy to the fusion that makes stars shine, to well,
life, they all have one thing in common. They all have to follow the laws of physics. If you look in
a textbook, you get to some paragraph that lists life as like several attributes. Stuff like, it's
organized into cells or that it can grow. That it can reproduce, that it uses energy. So you sort of
get this like checklist of what is life. Then I noticed the longer that you study, you start to
realize that there are exceptions to these things. I mean a crystal can grow and replicate itself.
Soap bubbles have very particular cellular order. The ocean,
just the water and the chemicals dissolved in it can maintain homeostasis and pH
and stability. Just consider a simple flame. It can reproduce, it uses energy. It can grow
and even form complex structures, but you probably wouldn't argue that a candle is alive.
As you said, biology, that's what I've learned when talking to biologists,
that is the science of exceptions, isn't it?
And so it makes me think that what we learn in school about what is life is
totally insufficient for really describing what it actually is.
Yeah, absolutely.
So I'm surprised and curious, why a physicist would be so interested in questions about life.
I think, ultimately, cosmology, so what I do, astronomy, you know, those subjects. They raise
profound questions. The first question I get when I talk about size and scale of the universe from
people, from audiences is, "What does it all mean? What am I to take from these things that
you are saying?" And that word, meaning, doesn't sound like a scientific term. But clearly that
meaning exists in the universe, 'cause it means something to us. Our great hero, Carl Sagan
said, I remember there was a great celebration of our civilization on Cosmos.
And he showed that the arts and the music and the architecture, and at the end of it, he said,
These are some of the things that hydrogen atoms do given 15 billion years of cosmic evolution.
But in any case, that's true, isn't it? It's true. Long answer to a short question is that I think
that life is absolutely fundamental to understanding the universe.
So, let's look at life through Carl Sagan's perspective, as atoms doing interesting things,
and see what we can learn. This view of life as very interesting physics
actually goes back to the physicist, Erwin Schrödinger. In 1944 he published this book,
"What Is Life?" Schrodinger asked, if we look at life down at its most basic units,
very small things like atoms, maybe we can use physics and mathematics to describe how big
bunches of those atoms can form complex things like you and me. This was a very
different approach versus someone like Charles Darwin, who viewed the world through an animal or
ecosystem sized lens. My conversation with Brian touched on a few ideas from physics that together,
can help us understand what makes life different from the other, less interesting atoms in the
universe. Energy is the first big thing that is required for living things to do what they do. So,
what is a useful definition for energy in terms of how it can help us understand life?
I mean energy is, it's notoriously, I mean we can define it mathematically and say,
kinetic energy is half mv squared, and things like that. If you go to relativity, by the way,
then you end up saying, it's the component of the four vector that points in the time direction.
It's a thing that's conserved. That's why it's useful in physics. It's not created or destroyed.
This is a deeply strange truth about the universe.
From the Big Bang to today, all of the energy that ever was is still out there. This energy
can change from one form to another, but all there is all there is. And since the beginning of time,
that energy has been getting more disordered along with the whole universe.
If you imagine a cup of coffee and you delicately put the cream on top of the cup of coffee,
so that's an ordered system. So, we have created order. The cream's on the top and the coffee's
underneath. And then if you sit there and maybe you give it a little stir just to give it a kick,
and it mixes up so it becomes more disordered.
But in the process, you get complex structures, swells in the cream, swells in the coffee.
So, a pattern emerges spontaneously on the road from order to disorder.
These patterns can be so complex that no other coffee and milk in the universe is exactly
like this one. But eventually as time goes on, we end up in a state of maximum disorder. A
perfectly boring cup of coffee. And the universe has been doing basically this.
The universe started off in a highly ordered way at the Big Bang, and it's on its way to a
more disordered and increasingly boring state. The heat death at the end of the universe. This is all
described by the second law of thermodynamics. The universe, as in, the whole entire universe
is evolving towards increasing entropy, aka more disorder. So what does this have to do with life?
And in the process, there can be swells in the coffee, and in that sense we're swells
in the coffee. So, we're almost like an inevitable consequence of the march from order to disorder.
I think maybe the basic understanding that most people have about complexity in the universe is
that it's supposed to run the other direction. It's supposed to be the things don't get more
interesting and complex. They get more or disordered. So is life breaking the rules?
No, you can have local complexity emerge. So, in the language of thermodynamics, it's a reduction
in entropy, so things can get more ordered, as long as you pay the price in the environment. So
the environment has to get less ordered. That's why your refrigerator works. A refrigerator,
how do you cool the inside? That's making order inside. You can see that, when you put water into
it, it turns into ice crystals. So by cooling it down, you're allowing this complexity to
emerge. But how you do that? Well, you've got a big heater on the back. So, the key part of
the refrigerator is not something to do with the inside. It's the big heating element on the back,
which is throwing disorder out into your kitchen. And where does it get the energy
to do that come from? It comes from a power station, which might be burning fossil fuel,
or it might be nuclear power, whatever it is. But you can trace it back. Now you might say,
and you're probably gonna say, "Well, okay then, but where does the original order come from?"
And it's a very good question, it's the Big Bang. So ultimately, the profound question
is why was the universe born with a reservoir? You can think of it as a reservoir of order which can
unravel over billions of years and allow complex structures to exist in the process of unraveling.
Our Sun, like every other star in the universe, is a tiny pocket of complexity and order
in a universe becoming more disordered. What stars do basically, is take a bit of
that original order from the beginning of the universe, and hold on to it for a while, slowly
giving it up over billions of years, in a more disordered form. Energy in the form of sunlight.
You probably know that all life on Earth today gets its energy from the Sun, whether directly
through photosynthesis, or indirectly, by eating things that do photosynthesis,
or eating the things that eat the things that do photosynthesis.
But ultimately it's the Sun, our little clump of order in an increasingly disordered cosmos,
that's basically the furnace powering the steam engine of life. So we're still tapping
this reservoir from the very first moments of the universe and using it to do interesting things.
Yeah, so it's a good approximation. Now, the Earth radiates as much energy out into space as
it receives from the Sun. 'Cause if it didn't, it just heats up. But essentially what life is doing
is sitting in that cascade of energy.
And it's just siphoning a bit of order off from the sunlight.
This is a really important and kind of mind-blowing point. When it comes to order and
entropy, not all energy is created equal. Earth absorbs as much sunlight energy as it gives off
in the form of infrared radiation energy. But that infrared radiation energy has more disorder than
the original sunlight. When a leaf absorbs visible light from the Sun, it grabs a bit of that order,
it uses this order to do interesting things like split water into hydrogen and oxygen,
and to make sugars, then it pays the universe back for the order that it borrowed by releasing
infrared radiation. The Sun isn't just a source of energy. It's a source of
order. When cells borrow that ordered energy and turn it into things like
DNA and ATP, we send back what we owe as less ordered energy in the form of heat.
But it is true that as you sit there, you're actually hastening the demise of the universe,
