00:00Life is fundamentally different from dead stuff.
00:03Or is it?
00:04Physicist Erwin Schrödinger defined life this way.
00:08Living things avoid decay into disorder and equilibrium.
00:13What does this mean?
00:14Let's pretend that your download folder is the universe.
00:17It started orderly and got more and more chaotic over time.
00:21By investing energy, you can create order and clean it up.
00:26This is what living things do.
00:28But what is life?
00:30Every living thing on this planet is made of cells.
00:34Basically, a cell is a protein-based robot too small to feel or experience anything.
00:39It has the properties we just assigned to life.
00:42It has a wall that separates it from the surroundings creating order.
00:46It regulates itself and maintains a constant state.
00:50It eats stuff to stay alive.
00:52It grows and develops.
00:54It reacts to the environment.
00:56And it's subject to evolution.
00:59And it makes more of itself.
01:01But of all the stuff that makes up a cell, no part is alive.
01:05Stuff reacts chemically with other stuff,
01:08forming reactions that start other reactions, which start other reactions.
01:12In a single cell every second, several million chemical reactions take place,
01:17forming a complex orchestra.
01:20A cell can build several thousand types of protein.
01:23Some very simple, some complex micro-machines.
01:27Imagine driving a car at 100 km an hour
01:30while constantly rebuilding every single part of it
01:33with stuff you collect from the street.
01:35That is what cells do.
01:37But no part of the cell is alive.
01:40Everything is dead matter moved by the laws of the universe.
01:44So is life the aggregate of all these reaction processes that are taking place?
01:49Eventually, every living thing will die.
01:52The goal of the whole process is to prevent this by producing new entities.
01:57And by this we mean DNA.
02:00Life is, in a way, just a lot of stuff that carries genetic information around.
02:04Every living thing is subject to evolution,
02:07and the DNA that develops the best living thing around it will stay in the game.
02:12So, is DNA life then?
02:15If you take DNA out of its hull, it certainly is a very complex molecule,
02:20but it can't do anything by itself.
02:22This is where viruses make everything more complicated.
02:26They are basically strings of RNA or DNA in a small hull
02:30and need cells to do something.
02:33We're not sure if they count as living or dead.
02:36And still, there are 225 million cubic meters of viruses on Earth.
02:41They don't seem to care what we think of them.
02:44There are even viruses that invade dead cells and reanimate them
02:48so they can be a host for them, which blurs the line even more.
02:52Or mitochondria.
02:54They are the power plants of most complex cells
02:57and were previously free-living bacteria that entered a partnership with bigger cells.
03:02They still have their own DNA and can multiply on their own,
03:06but they are not alive anymore.
03:09They are dead.
03:11So they traded their own life for the survival of their DNA,
03:15which means living things can evolve into dead things
03:18as long as it's beneficial to their genetic code.
03:21So maybe life is information that manages to ensure its continued existence.
03:27But what about AI, artificial intelligence?
03:31By our most common definitions,
03:33we are very close to creating artificial life in computers.
03:37It's just a question of time before the technology we build gets there.
03:41And this is not science fiction either.
03:44There are a lot of smart people actively working on this.
03:47You could already argue that computer viruses are alive.
03:50Hmm. Okay.
03:52So what is life then?
03:54Things? Processes? DNA? Information?
03:59This got confusing very fast.
04:02One thing is for sure,
04:03the idea that life is fundamentally different from non-living things
04:07because they contain some non-physical element
04:10or are governed by different principles than inanimate objects
04:14turns out to be wrong.
04:16Before Charles Darwin,
04:17humans drew a line between themselves and the rest of living things.
04:21There was something magical about us that made us special.
04:25Once we had to accept we are, like every living being,
04:28a product of evolution,
04:30we drew a different line.
04:32But the more we learn about what computers can do and how life works,
04:36the closer we get to creating the first machine that fits our description of life,
04:40the more our image of ourselves is in danger again.
04:44And this will happen sooner or later.
04:46And here's another question for you.
04:49If everything in the universe is made of the same stuff,
04:52does this mean everything in the universe is dead
04:55or that everything in the universe is alive?
04:58That it's just a question of complexity.
05:01Does this mean we can never die because we were never alive in the first place?
05:05Is life and death an irrelevant question and we haven't noticed it yet?
05:09Is it possible we are much more part of the universe around us than we thought?
05:14Don't look at us.
05:15We don't have any answers for you,
05:17just questions for you to think about.
05:19After all, it's thinking about questions like this that makes us feel alive
05:24and gives us some comfort.
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