1,441 words · auto-generated from the episode video
14:52>> And when I eat all that much, I'm going to spew out radiation. That radiation is going to shock all of the rest of my food away. M >> you see what I'm saying? It's the same argument of hydrostatic equilibrium that we've been visiting a lot on this podcast. The idea is >> if I eat too fast, >> then the radiation from [snorts] all of that eating because the black hole is going to accrete all this mass. The mass is going to start heating up. That's going to cause radiation. That radiation is going to be enough to shoe all of the rest of my mass away. So, there's a maximum limit at which I can grow. >> 3,000 calories a day max. >> Max. Right. And if you do too much, then
15:33there's no food around you. >> Right. Right. >> Okay. That's the idea. >> Look, that's very interesting. >> Okay. So, that's something called the Edington limit. It's named after Arthur Edington, who's a uh amazing man of science in history. Also a bit problematic. And by a bit, I mean a lot. But [laughter] that's um >> for another episode. >> For another episode. In any case, he finds this sort of limit to how how much stars can grow. What's the luminosity of these stars? And you can apply that same logic to black holes. >> Got it? >> Okay. So, from that we get an accretion rate. It's like how much am I eating? >> Yes. >> And from that I can have a characteristic growth time scale >> of like how how much time do I need to
16:14grow by a certain factor >> because you know what your limit on eating is. And so you'll know if I'm trying to gain 10 pounds or lose 10 pounds. >> Yeah. How long is that going to take? >> Take, >> right? >> Cuz you're you have a max. >> Yeah. And and for this by a factor of e because everything is an exponential exponential to the e. So if I want to grow by a factor of e, which is like 2.7ish, I need to wait 50 million years. >> Yeah. >> All right. 50 million years to to to grow by a factor of 2.7. >> All right. Now, these red dots that we see in the universe, they're at a red shift of seven, which means they're approximately 800 million years after the Big Bang. 800 million years is not a lot of time. >> No.
16:55>> Even especially if you're growing at only 50 million years per factor of 2.7, right? >> Okay. >> Right. >> So, there's two possibilities. >> One is you've got these light seeds. Light as in like light instead of heavy. >> Okay. >> You have the first stars. These are population three stars. They're the remnants of the very first stars. When the very first stars that are, you know, about, let's say, 100 mass, 100 times the mass of the sun or a thousand times the mass of the sun, very, very old stars, when they blow up, they're going to make a black hole. And that black hole is going to be about 100 times the mass of the sun. And so, in order to reach 10 the 9 times the mass of the sun in 800 million years, you got to be
17:37continuously eating at the Edington limit. >> I see. Stuffing your face. stuffing your face for like hundreds of millions of years. >> You got you got to be going like like the the hot dog eating competitions. Have you seen those? >> Kobayashi. >> Yeah, dude. So So you got like you got to be in the zone. >> Yes. >> For hundreds of millions of years. >> Constantly. >> Constantly. >> Very improbable. >> Seems Yeah. >> Seems improbable to just be going at it. Yes. >> Right. Okay. So the second possibility is there's heavy seeds which is this direct collapse. You don't make a star. You just got a gas cloud. The gas cloud maybe runs into another gas cloud
18:18reaches critical mass and then the whole thing just falls inside the Schwarz load radius. You get a black hole. No star needed. >> Mhm. >> For that the advantage is you you can reach that high mass 10 the 9 mass of the sun. You can reach that but the conditions got to be perfect. You got to have really pristine gas. It's got to be like sort of spherically symmetric and um you need a a lot of UV background so that the the gas doesn't cool down to form stars. It has to like really just be focused on making a black hole. Again, >> improbable, >> right? Right. So, the idea is the current the the light seed and heavy seed options >> uh don't pass the sniff test.
18:59>> Yeah. They they really don't. It's like both are like super improbable. On the one hand, you have you have like a black hole that is just eating max out like in the zone and then the second the the conditions to create that first black hole are like perfect. Okay. And the number of these little rod dots that we're seeing it just doesn't make sense. There's too many. >> There's too many for all of them to have just this perfect >> like condition. >> The idea is we're seeing so many of them. So you're saying this thing that's improbable is happening like frequently. >> Yeah. Which is the whole point. Yeah. So, what are we doing? All right. So, so this was the big conundrum, right? >> Yes. >> So, what can we do? Well, let's point an X-ray telescope at it. So, they had the
19:40Chundra X-ray telescope pointed at it. No X-rays. That's weird. >> Okay. >> Black holes spew a lot of X-rays. >> Okay. >> Because stuff gets really hot and if stuff gets really hot, it's going to like >> spew out very high energy radiation. It also there's no radio emissions. You look at you look at it from the Earth with really nice radio telescopes that can localize that point source. No radio emissions. Black holes should have radio emissions because there's high magnetic fields. And if charged particles are spinning around in that high magnetic field, >> it's going to shoot off. >> They're going to shoot off radio waves. So no X-rays, no radio waves. What do we have? >> Well, let's look at the photo. Like what do we have? Well, the James Web Space
20:21Telescope has a really nice spectrograph, right? So we can look at the phototric spectra and this is from a particular little red dot called the cliff. >> The cliff. And the cliff you can see the cliff. Right. >> Yeah. >> So at shorter wavelengths you've got a little bit of light coming through in the ultraviolet. >> Yeah. >> And then right at about 300 and like 380 >> nanometers you get a you get a really high spike. Everything that's over that 365 sorry 365 nanometers you get a lot of light coming in. >> Yeah. >> Okay. So you get this like distinct Vshape. This particular one is called the cliff because it's such a nice
21:02spectra. >> Okay. So the question is what would actually cause >> a spectral like this where >> you've got a little bit of ultraviolet but right at 365 there's nothing. >> Mhm. >> Almost nothing. And then for any wavelength longer than 365, you've got a lot of light coming through. Well, 365 nanome and this is in the rest frame. So they had to, you know, shift everything to suppose I was suppose this thing wasn't moving away because in reality that light is going to be somewhere in the infrared, right? Because it's moving away. But you can shift it back into the rest frame and you can say, okay, at 365 there's nothing. And then anything higher than 365 nanometers which means
21:43lower in energy because higher wavelength lower energy we're getting a lot of light. >> Let there be light at 365. >> So 365 nanometers is something called the Balmer limit. Okay. This is what happens because any piece of light that is higher energy than the 365 nanometer wavelength, it ionizes hydrogen. that photon has enough energy to kick out an electron if the electron is in the second shell of