Deinococcus radiodurans — “Conan the bacterium”

22:16an impact ejection? Which is the idea of like a meteor comes in, slams into the Earth at insane energy, several atomic bombs. Can it survive this? So, at sea level, we've got about .0001 gigapascals of pressure right now. Where we're at. Okay. Okay. The Mariana's Trench is at .1, which is about 1,000 times more than at sea level. >> Okay, can I ask you a question? When you say pressure, how for our audience, like how would they experience what that means? Like cuz we do experience what Or like how would you describe Yeah, pressure is Yeah, that's a good point. So, pressure is force per unit area. That's how it's

22:56defined in physics, right? It's the amount of force that you're pushing on some amount of area. Now, you can imagine if I'm pushing hand to hand, >> Mhm. there's not a lot of pressure. >> Yeah, yeah. But imagine now I have a pin. Mhm, yeah. >> Right? Like the thumb tack. >> Yeah, that does it. >> And now I push. Yeah. Why does it go through my hand? Because there's a lot of pressure. The same amount of force is being concentrated on a tiny bit of area, and that pressure is enough to pierce my skin and cause a lot of damage. >> That's a really good way That's really good analogy. Yeah. >> That's That's what I mean by pressure. It's like per per amount of area on your surface, how much is it pushing down? >> Mhm. Okay? At sea level, it's not a lot.

23:37I mean, the amount of pressure that we have pushing in is the same as the amount of pressure we have pushing out from our blood and everything, and that's why we don't like get crushed. Um unfortunately, do you remember the the Titanic? Yeah, it was the submarine thing. >> submarine thing? When you get down there, there's so much pressure, and the thing gave way, everything collapsed, right? And then it just like completely killed everything. >> Yes. >> So, that's That's pressure acting, right? >> Okay, okay. >> And at the experimental low end for this particular paper, you've got 1.4 gigapascals. That's 14,000 times atmospheric pressure. >> Jesus. And on the high end, you have 3 gigapascals, which is 30,000 atmospheric pressure. Now, why do we need to

24:19Why do we need to like go that far? Okay? >> In terms of the amount of pressure is well outside what we as humans >> as humans, right? Like like even on Mars, Mars is actually low pressure. >> Mhm. It's way lower pressure atmospherically because Mars is smaller, so it doesn't have a big enough atmosphere. So, the atmosphere isn't like actually pushing down. So, why do we care about these high pressures, right? The reason we care about high pressure is to escape Mars, the rock has to es- to reach an escape velocity, right? In order to get all the way to Earth or something like that, which is about 5 km per second. Okay. On Earth, it's about 11 km per second. But in any case, to get that fast, direct acceleration means that you need like 50

25:00gigapascals of pushing I see. >> in order to get there. You're never going to survive that. On the other hand, in 1984, there was a theory called the shockwave spallation theory. This is the idea that an a meteor is going to come in and it's coming in so fast that the the ground is going to act like a viscous fluid. Oh wow. >> And that's actually what happens when meteors impact. They're coming in so fast with so much energy that the ground, the shockwave is no longer a solid. It's like this viscous fluid. So, the meteor comes in and then the stuff around it bounces up, right? Because

25:41you've Yep. pummeled in. And so, now the stuff around it is like going up. There's this like compression wave that like rebounds. It rebounds from that impact. And that rebound is going to project tile stuff Mhm. >> out into the air. To escape the gravity of the body. And that's how we get Yeah, and that's how we get that escaping, right? >> Okay. >> And to get that escaping, that is about a 5 gigapascal to 1 gigapascal shock. Now, that's lower than the 50 gigapascals that we thought was going on, right? So, so the idea is the meteor comes in, hits it, there's stuff around, and that stuff that's around is going to get shot up.

26:23>> shot back up as a rebound. And that rebound might be enough. So, it's still it's still 330,000 times the atmosphere of the Earth, but it's still it might be enough that these things survive. The other clue as to why it would survive is because it's not really a sustained pressure. This is transient. This is This happens over like a microsecond. This thing impacts, this thing goes in, the the pressure that this thing that the ground feels is over a microsecond, right? It's extremely short. So, maybe that brief shock will leave the cells mechanically intact. That's the question that they're trying to answer. >> Okay. This this this makes sense. So so

27:03just to briefly summarize and cuz the the idea is when we are trying to ascertain uh if panspermia is a thing, which means life arises on one rock and then moves to another rock that's orbiting around a star. The the life on rock number one needs to be able to have enough to escape the atmosphere. Yeah. We have rockets. But in lieu of rockets, you have some object come, disrupt the ground and it with enough force such that it shoots stuff out of the gravitational pull of the rock that you're on. And so now you're in space and you're traveling around. And so

27:45there are all these stages of that entire process for how does an organism get from one place to another when it's not on a rocket? >> Yes, exactly. And and this is the theory, right? The thing comes in, there's a rebound, and then it gets flung out into space. And so now we get to the actual paper, right? The actual paper, and if we go to photo 14 >> Yes. is a paper in PNAS, which is the Proceedings of the National Academy of Sciences. Um not that other word you weirdos were thinking about. >> No, this is PNAS. Everyone knows about PNAS on science, guys. Come on. Um it's about extremophile survives the

28:25transient pressures associated with impact-induced ejection from Mars. That's exactly what they're doing. They're making the case that this particular bacterium, D. radiodurans, can survive that insane pressure all the way up to 3 gigapascals. Right? >> That's that I mean, that's a big because that totally changes the calculation when we talk about things like the Fermi paradox. Where is everybody? >> And we're going to we're going to get to that. We're going to get to that. So let let's pause on that. And let's talk about how they actually did the experiment because this is from first principles. We're going to talk about how they did the experiment. First you need to biologically sample prep, right? So, here's what they did. They had

29:07um the radio duran cells, the bacterial cells in this like circular plate Mhm. and they sandwich those cells, this about a billion cells that they they put inside like a petri dish, but it's like a circular petri dish. They sandwiched those cells between two large steel plates >> Mhm. and then they seal it. It looks like it almost looks like a Canon camera lens. >> Yeah, totally. We're in the center Yeah, in the center you have your biological sample and then you're sort of like collapsing a bunch of steel plates on top, right? Now, what we're going to do with that plate is we are going to hit it with a gas gun. Okay.