Can Life Really Be Explained By Physics? (featuring Prof. Brian Cox)

It's a little bag that smashes things and stacks protons on one side so we can wash them through this waterwheel and make fuel to keep doing other interesting things in cells. Literally, why mitochondria are the powerhouse of the cell. Now you know. One of the great commonalities of all living beings is the way they manage energy. I'm thinking in particular of the fact that all living things pump protons through membranes. And as far as I know, that is common to everything.  I don't think there is an exception to that. Believe it or not, this universal trait can give us a big clue about how

life

may have begun.   Or at least where it started.

In the rocks of deep-sea hydrothermal vents we find pockets with many protons on one side and few on the other. These rivers of protons are a natural energy source that many scientists believe billions of years ago fueled the first transition from regular chemistry to living biochemistry. I tend to think that initially the origin of

life

is a transition from geochemistry to biochemistry, which it must have been. You have to have a world, it's geologically active and somehow the chemistry becomes complex enough that you can store information and copy it. Information is the other key ingredient that seems to separate living things from non-living things.

So what does that mean? In each living cell, in addition to the energy or molecular machines that we have already mentioned, we can find one more example of complexity and order hidden in this universe that is on the path to disorder.   DNA and the genetic code. One of the greatest discoveries in the history of biology is that there is a physical molecule that carries the instructions for living: DNA. The information is in the structure. It's an arrangement of atoms in an ordered pattern and that allows us to extract some meaning from it and do the interesting things that life does.   Now, spoiler alert, eventually you, I, and every living thing on Earth will die.

But life itself will continue thanks to this information stored in ourselves. Because I share some of that information with you. I share a little with other apes, I even share a little of the banana. Instructions for living are a form of information that is larger than any living thing. My idea is that the Earth

really

is a giant genetic database. And that data happens to be stored in small local objects. So there are fragments of it. So there is something in me and something in the blades of grass etc. Because what we are talking about here is the gradual and ever-changing change in where information is stored in this great database of life.

But this raises another big problem. And it's one we don't have an answer for. If we could somehow go back in time and meet all the ancestors along the way, from the first animals to single-celled microbes, all the way to something so simple that it can copy itself using only chemical reactions. Well, at what point do you decide that it is the first living being? It's a label, right? It's semantics, I think.   It reminds me of the debate in astronomy about whether Pluto is a planet.   Because, first of all, I don't care, but that's because I'm not a

prof

essional astronomer.   They spend years meeting and defining what a planet is.

It's actually an interesting world orbiting a star. It may not break through, it may not be big enough to be a planet, etc., but it's just an interesting world.  So, I don't care what it is. I think we will only truly understand how life could begin when we see a second genesis somewhere. That's why Mars is so interesting and important, because it is the most accessible example possible.   It's interesting to note that if we're interested in questions about the origin of life, it might be easier to see that on Mars than on Earth, because on Earth the evidence has been erased.   The only evidence we have is in our genome.

They are the current living beings, which are separated by about 3.8 billion years from the first living beings. But on Mars it has been frozen, with little geology and no weathering, for more than three billion years. So if life started on Mars, it's entirely possible that we have more pristine evidence of how it started on that planet than we do on this planet. Of course, not everyone thinks that these are questions that science can answer. I had a

prof

essor in college, a biochemistry professor, who once told us that finding a useful definition for life, well, science couldn't help you with that.

As he himself said: "It was a question for poets." And I asked Brian if he was okay with that. Our presence in the universe is probably the most, well, one of the most interesting scientific questions. And possibly the most important and interesting scientific question. How did we get to be here?   And that doesn't just mean how the universe began. It literally means, how did atoms on this planet become complex enough to start exploring the universe? Living beings are one of the categories of objects created by the laws of nature, which the laws of nature allow to exist.

Another is the stars. So we understand, we say, well, let's understand the origin of stars and we know what we are talking about. So I think in that sense, it's perfectly reasonable to say, well, let's understand the origin of living things. Because living beings are a structure in the same way that stars are a structure.  They are much more complicated. It is the deepest question: how did life arise in this universe? In live shows, I start with the question: what does it mean to live a finite, fragile life in an infinite, eternal universe?   Then I immediately say I don't know because if I knew I would charge more for tickets.

At least you're honest. Or actually, when we look at everything we know about being alive and try to boil it down to protons and the movement of heat and energy from here to there or that the letters of the genetic code are just a repeating pattern of information, that can be uncomfortable. I mean, being alive certainly seems like more than that. Nature sometimes forces you into uncomfortable positions.   Often when you look at it. And that's good for you, it's good that you're confused. I hope that idea applies to life.  Because uncertainty can be emotion.   And it is what places you on the edge of the abyss, on the edge of human knowledge.

I mean, taking a step forward is exciting. You are parachuting into the unknown. I think it's one of the big unanswered questions and that's what makes it interesting. And that's what interests me. I am interested in questions that we have not yet answered, but that we have the possibility of seeking an answer. Stay curious. If you enjoyed this episode and would like to learn more about Professor Brian Cox and all of his science communication work, you can check it out here. Or simply follow the links in the description. Thanks to Policygenius for supporting PBS.  Policygenius is an insurance marketplace, not an insurance company.

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Those are all great questions. And “Subcultured,” a new PBS documentary series, answers those questions and more, exploring lesser-known communities and the people who have had a big impact on the mainstream. You can watch it   on “PBS Voices”. There's a link in our description and let them know Joe sent you. Actually? Actually? Actually?  Actually? How high can I go? Erwin Schrödinger. Schnell! Schnell! If you must have the Erwin Schrodinger, stay curious. He got over it.