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It's time to explore a big question while we watch a ciliate go through its last moments.

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This is a ciliate, Loxodes magnus.

It is about to die. Of course, depending on your time scale...we’re all about to die.

To the grand canyon, or the sun...things that have existed for millions or billions of years, we are each weird little bubbles of peculiar chemistry that form and then pop...form, and then pop. But this ciliate, and with our new microscope you can really see those cilia beating, is about to pop right before your eyes. It looks fine right now.

You can even see, inside it, it’s last meal, a Trachelomonas. So we don’t think it’s starving to death. It seems to be trucking along just fine.

Loxodes Magnus are microaerophilic organisms, preferring a low concentration of dissolved oxygen in their environment, but not too low. So maybe the concentration on the slide was too high, though we’ve witnessed many others who have been just fine in our preparations. So no, we can’t tell you why this ciliate is about to die...but we can tell you that right here...that’s where James, our master of microscopes, first saw something strange.

The moment the ciliate shifted direction, a little trail of cell membrane and cytoplasm. No reason. Nothing grabbed it, it didn’t snag on anything.

But a little bit of what was once a part of the organism was suddenly, no longer a part of it. That cytoplasm is full of complicated molecules that are what chemists would call, far from equilibrium. Equilibrium is the situation in which chemicals no longer have a tendency to react over time.

In general, a thing that you can say for sure is that all the stuff outside of living cells is either at chemical equilibrium, or it is headed there. Whereas stuff inside cells is not at equilibrium, and it’s not headed there either. How are all of these chemicals that, if left alone, would rapidly reach equilibrium managing to not do that?

Life. That is what life is. A bunch of chemicals that take in energy in order to keep each other from reaching equilibrium.

Quick break from our friend...the way we define life in biology classes is...wrong. It’s not even really a definition, it’s a set of qualifying factors. Life has to take in energy.

Life has to reproduce, it must respond to its environment, it must consist of cells. This is not a definition, it’s an attempt to draw a line, to create a boundary. And that makes sense for things that are actually amorphous and complicated, like social constructs.

But life is not a construct of our opinions, but of reality. Life is a chemical system that uses energy to keep itself from reaching chemical equilibrium. Why do they do it?

Oh, well maybe let’s not go /that/ deep, at least not today. Suffice it to say, a system that did this developed on this planet and now, billions of years later, it is still doing it. We have many things in common with this ciliate, and not to belabor the point, but one of those things is that we will die.

You’ve probably noticed by now that this video isn’t about what life is, it’s about what death is. It’s just that, first, we had to define life. Life is chemicals working together to take in energy to keep themselves far from equilibrium.

Death is not the return to chemical equilibrium. The process of decay can last decades. Likewise, many parts of my body will return to equilibrium over the course of my life, I’m shedding skin cells right now and so are you.

The atoms and molecules of my body are replaced with new ones over and over and over again. But I will only die once. Likewise, our ciliate has been shedding cytoplasm and cell membrane for minutes now, and that shed cytoplasm is dead, no doubt.

But the organism lives. Its chemistry continues. For now.

Death is the moment when the system that maintains the far from equilibrium state ceases existence. And we can imagine that at many scales. That can happen to individual bits of an organism, as it is happening to the chemicals spilling out of our Loxodes right now.

It can also happen to an individual cell in an organism. And that happens all the time. It is happening right now inside you.

It can also happen to an organism. That’s what we usually think of as death, with our focus, so often, on the individual. But we can keep moving up the scale and find yet other kinds of death.

When a common genetic system that was useful for keeping many similar but individual organisms alive ceases to exist, that is an extinction. A kind of death. And when the system that has kept all life on earth far from equilibrium for billions of years, that system that we all share of nucleic and amino acids, when that ceases to exist, that will be something else.

A terrible kind of death that we do not even have a name for. But it will be a death. The largest death, I suppose, until heat death, when everything in the universe has found equilibrium.

Our ciliate is about out of time now. I don’t know when we can call it, when we can pronounce the time of death, but this seems as good a time as any. Here, we have death.

The system that was using energy to keep itself from reaching equilibrium has ceased to exist. Thank you for coming on this journey with us as we explore the unseen world that surrounds us. And thank you as always, and of course to all of the people on the screen right now.

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