Chris Kempes

Yeah.

Yeah.

Exactly. And there's a lot to say about that. I mean, so one really interesting thing is that often the only way to explain what you see in organism structure or function is from a consideration of multiple constraints.

Exactly. And there's a lot to say about that. I mean, so one really interesting thing is that often the only way to explain what you see in organism structure or function is from a consideration of multiple constraints.

And so what you do is you say we find some way to write down what in some fields would be called a global cost function, where you put all of the terms of different constraints in that same cost function. And maybe one trait interfaces with multiple different constraints. And then we just optimize over the whole thing and find some global optimum under multiple constraints.

And so what you do is you say we find some way to write down what in some fields would be called a global cost function, where you put all of the terms of different constraints in that same cost function. And maybe one trait interfaces with multiple different constraints. And then we just optimize over the whole thing and find some global optimum under multiple constraints.

This is an old idea in engineering. And that often is the best way to explain complicated structures. So for vascular plants, which I was mentioning, you know, the original work on that showed it wasn't just about gravity. It's also about fluid flow through the vessels of the plant.

This is an old idea in engineering. And that often is the best way to explain complicated structures. So for vascular plants, which I was mentioning, you know, the original work on that showed it wasn't just about gravity. It's also about fluid flow through the vessels of the plant.

And it's about trying to fill space with all the endpoints of the network so that you can either distribute leaves in space to uptake, you know, atmospheric space to uptake sunlight or to distribute cells in the body and feed them all with this vascular network. So that's a place where you sort of have three main constraints that you're optimizing over.

And it's about trying to fill space with all the endpoints of the network so that you can either distribute leaves in space to uptake, you know, atmospheric space to uptake sunlight or to distribute cells in the body and feed them all with this vascular network. So that's a place where you sort of have three main constraints that you're optimizing over.

Absolutely. So I think we wouldn't – I'm willing to make bets about that actually. Okay, good. That if you get large multicellular organisms, they will have fractal-like vascular networks with a certain very specific fractal structure that have been outlined in the whole thread of work. that I was discussing before.

Absolutely. So I think we wouldn't – I'm willing to make bets about that actually. Okay, good. That if you get large multicellular organisms, they will have fractal-like vascular networks with a certain very specific fractal structure that have been outlined in the whole thread of work. that I was discussing before.

And so we have some evidence for that in that, you know, the vascular system in plants evolved independently of the vascular system in mammals, and yet they share a huge amount of the same structures. So that's convergent evolution with a huge evolutionary divergence in time One organism is motile, the other organism isn't.

And so we have some evidence for that in that, you know, the vascular system in plants evolved independently of the vascular system in mammals, and yet they share a huge amount of the same structures. So that's convergent evolution with a huge evolutionary divergence in time One organism is motile, the other organism isn't.

One uses sunlight for energy, the other eats things that use sunlight for energy. One's warm-blooded, one's not. And yet the vascular systems we find share certain commonalities because they are roughly the same size and obey in the same physics.

One uses sunlight for energy, the other eats things that use sunlight for energy. One's warm-blooded, one's not. And yet the vascular systems we find share certain commonalities because they are roughly the same size and obey in the same physics.

So I think these are sort of the ultimate astrobiological convergence.

So I think these are sort of the ultimate astrobiological convergence.

Yeah, so bacteria, we think of them as these tiny sacks of stuff, which in some ways they are. But even, as Sean was just saying, even then we get a factor of 10,000 in cell size, right? So that's four orders of magnitude from the smallest cell to the largest cell. And the smallest cell and the largest cell don't look like each other in lots of different ways that we can get into.

Yeah, so bacteria, we think of them as these tiny sacks of stuff, which in some ways they are. But even, as Sean was just saying, even then we get a factor of 10,000 in cell size, right? So that's four orders of magnitude from the smallest cell to the largest cell. And the smallest cell and the largest cell don't look like each other in lots of different ways that we can get into.