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Speaker 1: Hey, extraordinaries. Quick note for today's episode, I want to

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Speaker 1: let you know about my new book, To Aliens Speak Physics.

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Speaker 1: It's all about whether or not we can use physics

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Speaker 1: as a universal language to communicate with aliens, or whether

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Speaker 1: physics is more human than many people imagine. And the

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Speaker 1: book features cute cartoons of aliens from my friend Andy Warner.

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Speaker 1: If you've enjoyed my science outreach and wondered how you

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Speaker 1: could support me, this is how The book is out

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Speaker 1: in November fourth. Look for the link on the book

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Speaker 1: website www dot alienspeakphysics dot com. Okay, on to today's episode.

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Speaker 1: Whenever we look out into the universe, we see something

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Speaker 1: new that astonishes us, something beyond our wildest imaginings of

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Speaker 1: what the universe could do. It's a rich tapestry of

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Speaker 1: extreme physics, and yet all of it is described by

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Speaker 1: physics deep down. The mechanisms that create black holes, or

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Speaker 1: collide galaxies or explode stars are rooted in the basic

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Speaker 1: principles of physics, and so far we've been able to

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Speaker 1: come up with explanations for how these incredible events occur

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Speaker 1: and how the universe is vast and beautiful cosmos is shaped. Today,

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Speaker 1: we're going to dig into the physics that underlies one

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Speaker 1: of the most dramatic and literally brilliant phenomena in space,

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Speaker 1: astrophysical jets. Welcome to Daniel and Kelly's extraordinary, brilliant universe.

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Speaker 2: Hello.

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Speaker 3: I'm Kelly Waidersmith.

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Speaker 4: I study parasites and space, and before looking at today's outline,

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Speaker 4: I didn't know that astrophysical jets was a phrase that's

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Speaker 4: worth it.

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Speaker 1: Hi, I'm Daniel. I'm a particle physicist, and if I

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Speaker 1: had a baseball team, I might call them the astrophysical Jets.

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Speaker 4: Oh, is that because your brain is fixating on the

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Speaker 4: astros part?

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Speaker 1: It just sounds like a team that would score a

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Speaker 1: lot of runs.

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Speaker 3: Yeah, yeah, no and throw their balls really fast. I think.

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Speaker 4: So, when I was looking through the outline today, it

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Speaker 4: occurred to me that this doesn't feel like it's in

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Speaker 4: your main area of research, and so I was wondering

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Speaker 4: if you could tell us, like, when you are researching

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Speaker 4: something that you don't have knowledge of, like right at

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Speaker 4: your fingertips, what is your process like for preparing our outline?

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Speaker 1: Yeah, well, that's fascinating because this actually is sort of

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Speaker 1: right on the edge of my area of research. I'm

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Speaker 1: sort of card carrying particle physicists, which means that most

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Speaker 1: of my career is like, smash particles together at the

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Speaker 1: large had drunk collider, see what new kind of stuff

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Speaker 1: comes out. But it's always been super interested in space,

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Speaker 1: and like many people, I got into it because of astronomy.

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Speaker 1: But then I kind of discovered like astronomy is mostly

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Speaker 1: standing around in the cold looking at fuzzy things through

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Speaker 1: a telescope, and that wasn't as exciting to me. Apologies

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Speaker 1: to us. I mean, there's out there who love that

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Speaker 1: and thank you for doing it, but it wasn't for me.

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Speaker 1: But later in my career I got reinterested in astrophysics,

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Speaker 1: which isn't looking through a telescope, but it's like trying

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Speaker 1: to understand the physics behind what's going on out there,

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Speaker 1: like how does the star work, et cetera. So the

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Speaker 1: last few years I've actually written some papers on the

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Speaker 1: centers of galaxies and neutron stars and supernova and stuff

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Speaker 1: like this, but it is a little bit far from

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Speaker 1: my core area of expertise. So it means reading a

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Speaker 1: lot of.

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Speaker 3: Papers, got it. How many are you reading.

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Speaker 1: All of the papers all of them.

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Speaker 3: Wow.

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Speaker 1: I mean what I try to do is find a

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Speaker 1: review in that area, like, find somebody who knows the fields,

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Speaker 1: who's written like a broad perspective, read that really carefully,

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Speaker 1: and then read a bunch of the papers it references

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Speaker 1: to make sure I know what's being summarized and what's

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Speaker 1: actually going on, and what's the sort of the lore

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Speaker 1: all this kind of stuff. But it's a lot of

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Speaker 1: work to try to really understand a new field well

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Speaker 1: enough to try to contribute something to it. And you know,

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Speaker 1: I think you were asking though about like if you

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Speaker 1: want to talk about something on the podcast, not necessarily

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Speaker 1: like write a bunch of papers about it. But I

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Speaker 1: finally it's kind of similar to talk about something on

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Speaker 1: the podcast. You got to understand it really well because

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Speaker 1: my co host is really smart and asks hard questions,

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Speaker 1: and if I want to explain things correctly in a

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Speaker 1: way that actually clicks in people's minds, I got to

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Speaker 1: have it all up in my brain. So yeah, it

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Speaker 1: means reading a lot of papers when it's not my area.

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Speaker 1: Is that your experience? Also?

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Speaker 2: Yeah?

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Speaker 4: Yeah, when I'm working on my outline, I'm always asking

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Speaker 4: myself wwda, which is what will Daniel ask, trying to

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Speaker 4: figure out, like what other things do I need to

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Speaker 4: research that I am prepared for whatever?

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Speaker 1: Daniel asks, Yeah, I feel like everybody in my life

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Speaker 1: who I get to know, I have sort of like

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Speaker 1: a mini version of them in my head, like a

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Speaker 1: little model of them which constantly gets you know, improved

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Speaker 1: and updated and of course the most interesting people, it's

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Speaker 1: never actually correct, which is why they can wonderfully surprise me.

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Speaker 1: But I feel like that's a big part of understanding

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Speaker 1: who's somebody is. It's like comparing them to like the

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Speaker 1: little model you have of who they are and what

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Speaker 1: they might say and how they might react. It's super fun.

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Speaker 4: Do the models in here, and then we should change

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Speaker 4: subjects back to what we meant to talk about today.

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Speaker 3: But do the models in your head?

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Speaker 4: Like, are they like miniature people that you see or

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Speaker 4: are you just imagining their personalities without their bodies?

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Speaker 3: Like what do you imagine?

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Speaker 1: Are they in the room with me right now?

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Speaker 2: Right?

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Speaker 5: So?

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Speaker 1: I'm not schizophrenic, I'm pretty sure. No, it's just like you,

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Speaker 1: I just asked myself, you know, what would my kids

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Speaker 1: say in this situation? Or how would my wife react

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Speaker 1: to having this for dinner? Or what would Kelly ask

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Speaker 1: me if I said X y Z. You know, I

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Speaker 1: think they're just useful for trying to understand who somebody is.

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Speaker 1: But I also think it's helpful for understanding yourself because

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Speaker 1: you end up building also a model of yourself and

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Speaker 1: turning the inwards and anyway, I have my own Bonker's

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Speaker 1: theory of consciousness, but that's not what today's episode is about.

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Speaker 4: So when you sent me the outline for relativistic beaming,

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Speaker 4: I was like, I just have zero clue what this means.

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Speaker 4: We'll give us, like some background what we should expect

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Speaker 4: in this episode.

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Speaker 1: Yeah, this episode is about how the universe is constantly

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Speaker 1: surprising us. How every time we look out into space

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Speaker 1: we see something new and weird, something that doesn't quite

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Speaker 1: make sense. And yet if we apply our knowledge of physics,

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Speaker 1: it turns out we can crack it. We can make

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Speaker 1: sense that we can explain why it's happening, and often

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Speaker 1: it gives us an incredible view of what's going on

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Speaker 1: in extreme situations, you know, the cores of galaxies, when

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Speaker 1: things are really hot and dense and fast. But it

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Speaker 1: requires us to put together a lot of little pieces

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Speaker 1: of physics. Gravity electromagnetism, even special relativity, in order to

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Speaker 1: explain what we see out there in the universe. And

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Speaker 1: so today's episode is a story of like several decades,

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Speaker 1: almost a century, of trying to understand some stuff we

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Speaker 1: see out in space and finally putting it together. And

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Speaker 1: the last piece of that is a process called relativistic beaming.

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Speaker 1: And I had a bunch of listeners write to me

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Speaker 1: and ask me about these astrophysical jets that are omitted

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Speaker 1: from the centers of galaxies, and so I thought, let's

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Speaker 1: do a deep dive into all the physics that makes

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Speaker 1: those happen, especially that last bit, which I've never heard

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Speaker 1: anybody cover with a popular treatment. So that was the

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Speaker 1: motivation for today's episode.

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Speaker 3: Awesome.

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Speaker 4: I'm excited about today's episode because I love those moments where, like,

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Speaker 4: you've studied a bunch of different topics that don't necessarily

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Speaker 4: seem connected, but they turn out to be the building

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Speaker 4: blocks that you need to understand something completely different that

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Speaker 4: you probably wouldn't have been able to understand if you

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Speaker 4: hadn't done all of that background sort of foundational work

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Speaker 4: ahead of time.

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Speaker 3: Exactly, So let's learn, all.

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Speaker 1: Right, And so relativistic beaming is the last piece of it,

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Speaker 1: but maybe the least well known. So I decided to

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Speaker 1: go out there and ask our audience if they knew

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Speaker 1: anything about relativistic beaming to help us calibrate. If you

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Speaker 1: would like to participate for our future episodes, please don't

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Speaker 1: be shy. Write to us questions at Danielankelly dot org.

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Speaker 1: In the meantime, ask yourself, do you know what relativistic

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Speaker 1: beaming is? Here's what our listeners had to say.

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Speaker 5: Relativistic beaming.

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Speaker 2: I think that's when Chapman from the Yankees beams you

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Speaker 2: in the head by accident, and if that happens with

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Speaker 2: one of his fastballs, and then when that happens, time

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Speaker 2: will definitely go slower for you.

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Speaker 5: So relativistic relativistic beaming, well.

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Speaker 6: I can't remember off the top of my head. I

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Speaker 6: think it was to do with synchotrons. When electrons are

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Speaker 6: going near the speed of light and go around a corner.

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Speaker 6: The radiation they release very is in a very tightly

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Speaker 6: controlled spatial beam because of relativistic effects.

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Speaker 5: Relativistic beaming is the ability of a thought to enter

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Speaker 5: my mind and then instantly disappear as soon as I

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Speaker 5: try to act on it. But in physics, maybe it's

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Speaker 5: something to do with moving near massless particles near the

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Speaker 5: speed of light and taking advantage of some of the

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Speaker 5: relativistic changes that occur as a result.

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Speaker 4: I think my favorite answer, I mean, they were all great,

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Speaker 4: but was how a thought enters my mind and then

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Speaker 4: it's disappears. Relativistic beaming in that sense happens to me

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Speaker 4: like fifty times a day lately.

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Speaker 1: You have that experience where you have an idea and

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Speaker 1: then you try to write it down before it leaves

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Speaker 1: your brain, and sometimes it's like no pencil or paper,

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Speaker 1: you can't get to your phone, and you're like, oh, no,

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Speaker 1: it's gonna go away.

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Speaker 4: Yeah, it does, it go away, because it does for

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Speaker 4: me a lot of the time. Or are you just scared?

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Speaker 3: But it stays?

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Speaker 1: We does, okay, No, And then sometimes I have like

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Speaker 1: the remnants of the idea. I'm like, I remember feeling

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Speaker 1: this way about it and it was something about that

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Speaker 1: and what was it?

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Speaker 4: And man, yep, no, I all think to myself, don't

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Speaker 4: get distracted, don't get distracted while I'm looking for the pencil,

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Speaker 4: and then I always think about, like, oh, did we

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Speaker 4: make it as lunch this morning? And then it's gone

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Speaker 4: and anyway, Okay, so the thought that we do not

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Speaker 4: want to forget is what is relativistic beaming.

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Speaker 1: That's right. And the story starts with the things shooting

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Speaker 1: out of the centers of galaxies. These things called astrophysical jets.

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Speaker 1: And if you have a mental image of a galaxy,

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Speaker 1: you're probably imagining something like a disc. You've got a

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Speaker 1: bunch of stars a swirl together, and that's what the

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Speaker 1: Milky Way looks like, and that's what Andromeda looks like.

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Speaker 1: But there's another really important feature of galaxies that's not

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Speaker 1: always visible to the naked eye, and these are the

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Speaker 1: jets that shoot up and down from the poles of

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Speaker 1: the galaxy, out of the center. So instead of just

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Speaker 1: imagining a disk, imagine a huge beam of light beaming

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Speaker 1: up and down relative to the plane of the disk.

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Speaker 1: These are astrophysical jets.

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Speaker 3: Okay.

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Speaker 4: And so the jet is made of light. And just

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Speaker 4: so I make sure i'm picturing thing because you said photons, right.

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Speaker 1: Well, the jet has light in it. They are bright,

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Speaker 1: but they're actually not just made of light. They're mostly

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Speaker 1: plasma so they're like high speed particles. There's electrons, there's protons,

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Speaker 1: and there are photons as well.

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Speaker 4: Wow, okay, so I just want to make sure that

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Speaker 4: I've got my image of a galaxy correct. So at

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Speaker 4: the center of our solar system there's the Sun, but

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Speaker 4: at the center of a galaxy there isn't necessarily some

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Speaker 4: big thing. It's just what is at the center of

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Speaker 4: a galaxy. We talked about it maybe being a black hole,

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Speaker 4: but we don't really know right well.

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Speaker 1: There are lot of questions about what's at the center

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Speaker 1: of the galaxy because it's hard to see it's so

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Speaker 1: dense there. You know, I think a lot of people

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Speaker 1: have the image of a galaxy as like just a

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Speaker 1: bunch of stars sprinkled around, But there's a big density variation,

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Speaker 1: Like the center of the galaxy is much denser than

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Speaker 1: the outskirts. It's sort of like, you know, there's Manhattan

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Speaker 1: and then there's the suburbs, and then there's the excerbs,

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Speaker 1: and we live kind of in the suburbs. It's not

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Speaker 1: very dense, but it's not as rural as it is

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Speaker 1: further out in the galaxy. But near the center there's

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Speaker 1: a lot of stars and there's a lot of gas

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Speaker 1: and dust, so it is difficult to study the center

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Speaker 1: of the galaxy. But we do know a lot about

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Speaker 1: the centers of the galaxies also by looking at other galaxies,

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Speaker 1: and so far, every galaxy we've studied has a super

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Speaker 1: massive black hole at its center, with a couple of

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Speaker 1: exceptions in cases where we're like pretty sure the super

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Speaker 1: massive black hole has been ejected by like a recent

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Speaker 1: collision or something.

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Speaker 3: You can eject a super massive black hole.

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Speaker 4: We've probably talked about this on a prior episode and

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Speaker 4: my bad memory is why life is so endlessly surprising

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Speaker 4: to me?

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Speaker 1: But whoa yeah, yeah, Well, when galaxies merge, what happens

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Speaker 1: is the center's merge. It takes a long long time

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Speaker 1: and then the black holes merge, but not always. And

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Speaker 1: if you have like three galaxies merging at the same time,

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Speaker 1: two of them can work together and eject the third one.

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Speaker 1: And so yeah, gravitational kicks can eject the super massive

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Speaker 1: black hole from the core. It's not something we understand

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Speaker 1: super well. We do think that there are super massive

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Speaker 1: black holes at the cores of these galaxies. So imagine

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Speaker 1: a very very dense center of the galaxy and then

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Speaker 1: fewer stars as you move away from the center, and

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Speaker 1: then from the center shooting up and down. Are these

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Speaker 1: massive astrophysical jets. They can go for like hundreds of

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Speaker 1: thousands of light years.

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Speaker 3: Wow.

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Speaker 4: But they're not necessarily coming from the super massive black hole,

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Speaker 4: but just from like the general center.

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Speaker 1: We're going to dig into that later in the episode.

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Speaker 1: But we think they are connected. Yes, And this was

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Speaker 1: one of the central puzzles of astrophysical jets and continues

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Speaker 1: to be like what exactly is powering them? It's a

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Speaker 1: really fun question.

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Speaker 4: Okay, so stuff is shooting out, is it just kind

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Speaker 4: of like trickling out or is it moving really fast?

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Speaker 1: These are some of the fastest things in the universe. Like,

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Speaker 1: these jets are shooting particles out, often very close to

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Speaker 1: the speed of light. Like the energy of particles in

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Speaker 1: these jets is often much higher than energy of particles

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Speaker 1: in our experiments here on Earth, like the Large Hadron Collider,

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Speaker 1: we accelerate particles to have an energy of like around

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Speaker 1: five to seven tarra electron volts. That's trillions of electron volts.

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Speaker 1: But these galactic centers can accelerate particles to much higher energies,

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Speaker 1: which connects to lots of fascinating mysteries, like we see

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Speaker 1: super high energy particles arriving on Earth and we don't

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Speaker 1: understand where they come from. And one theory is that

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Speaker 1: they're being kicked to super high energy by these galactic accelerators.

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Speaker 1: Essentially that these centers of galaxies are like enormous guns

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Speaker 1: shooting out particles at super high energies.

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Speaker 3: But then you so you shoot the particles out, and

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Speaker 3: then where do they go? What happens to them?

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Speaker 1: Well, if you believe that it's natural, right, and there's

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Speaker 1: really fun theories out there about how like maybe aliens

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Speaker 1: have megastructures and they're engineering the centers of galaxies to

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Speaker 1: do particle physics experiments. That would be awesome two galaxies

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Speaker 1: pointing at each other. But in general, they just shoot

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Speaker 1: out into the universe. And you can see these astrophysical

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Speaker 1: jets if you look at it in the right spectrum,

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Speaker 1: really beautiful. You should google these images. They're spectacular. Often

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Speaker 1: these things are bigger than the galaxies themselves. They just

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Speaker 1: shoot out into the universe and then you know there

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Speaker 1: are magnetic fields out there in the universe, and these

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Speaker 1: are mostly charged particles and so they bend and they

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Speaker 1: fly around. And one reason why we like to study

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Speaker 1: the cosmic rays, the super high energy cosmic raise is

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Speaker 1: that they are less bent than the other particles. So

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Speaker 1: you want to know where something came from. If it's

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Speaker 1: like gotten bent and zipped around and changed direction one

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Speaker 1: hundred times, it's hard to tell. But if it's come

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Speaker 1: mostly straight at you, and high energy particles get less

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Speaker 1: bent by magnetic fields, then it's easier to sort of

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Speaker 1: point back in the sky and say where it came from.

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Speaker 1: Reason why we look for the super high energy particles

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Speaker 1: because they tend to point back to their source more

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Speaker 1: than lower energy particles. Yeah, very cool.

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Speaker 3: Okay, so they're going really fast. It's a lot of

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Speaker 3: different stuff.

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Speaker 4: Is this like a narrow beam or is this like

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Speaker 4: pretty wide and spread out.

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Speaker 1: It's pretty narrow like when they were first discovered, And

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Speaker 1: we'll dig into that. These are little sources like in

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Speaker 1: the sky. They're pretty small, which is one reason why

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Speaker 1: it was such a puzzle. And it's sort of amazing.

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Speaker 1: And you know, you have these galaxies and they're emitting

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Speaker 1: these things up and down the north and south pole

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Speaker 1: from the center and it's fascinating because it's not shot

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Speaker 1: out by the super massive black hole itself. Obviously, black

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Speaker 1: holes do not emit photons. It's not like, you know,

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Speaker 1: black holes are shooting particles out into space or anything

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Speaker 1: like that. But the environment the black hole creates, and

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Speaker 1: in general, the environment of the galaxy might be the

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Speaker 1: thing that's powering these particles and creating these beams.

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Speaker 3: Awesome.

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Speaker 4: So we've gotten to the what, and now we're going

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Speaker 4: to take a break, and then we'll get to the why.

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Speaker 4: Why do you get astrophysical jets? Not the baseball team?

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Speaker 4: All right, we're back. We've described astrophysical jets, and now

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Speaker 4: Daniel's going to help us understand why you get these

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Speaker 4: bursts of loads of different kinds of things coming out

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Speaker 4: of the center of galaxies.

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Speaker 1: Yeah, and I think a fun way to attack this

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Speaker 1: is to take us through the history in the last

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Speaker 1: century of people trying to understand them and putting together

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Speaker 1: lots of different things simultaneously. Because astrophysical jets are connected

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Speaker 1: to something else we've probably heard about, which are quasars.

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Speaker 1: Let's put astrophysical jets in our pocket for a minute

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Speaker 1: and talk about the history of quasars, why they were confusing,

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Speaker 1: how we understand them, and then how they come back

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Speaker 1: together to help us understand astrophysical jets.

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Speaker 3: Let's get into the quasar question.

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Speaker 1: So quasars are fun because, like the word itself is

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Speaker 1: like sounds super cool and science fiction. And they're name

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Speaker 1: because we didn't understand what they were, right. So quasars

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Speaker 1: are short for quasi stellar objects. And they were first

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Speaker 1: found back in the nineteen fifties when we didn't really

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Speaker 1: understand a lot about the galaxy. Oh it's only like

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Speaker 1: twenty or thirty years since we understood that there were

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Speaker 1: other galaxies out there in the universe, and we started

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Speaker 1: studying these things they called nebula that turned out to

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Speaker 1: be other distant galaxies. And then in parallel, we had

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Speaker 1: the birth of radio astronomy. You know, astronomy used to

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Speaker 1: be just in the optical like you look through a

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Speaker 1: telescope and you see, what do I see out there?

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Speaker 1: And let's make a map? But radio and World War

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Speaker 1: two led to the advent of radio telescopes. People listening

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Speaker 1: to the sky in the radio and what they found

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Speaker 1: were these radio sources in the nineteen fifties where they

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Speaker 1: couldn't find any optical objects as well. They were like hmm,

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Speaker 1: there's something out there that's emitting in the radio, but

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Speaker 1: the telescopes at the time couldn't see anything there in

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Speaker 1: the visible so they're like, what are these things?

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Speaker 4: So then are they quasi objects because they're like, maybe

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Speaker 4: that's from space. I don't know, maybe we messed something up,

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Speaker 4: like why, yeah, why the quasi part?

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Speaker 1: Yeah exactly. They didn't understand what they were, so they're like,

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Speaker 1: maybe there's something like stars because they're sort of localized,

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Speaker 1: but there's no visible object there initially, so it was

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Speaker 1: a real mystery at first, which is why I think

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Speaker 1: they went for like, let's give this kind of a

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Speaker 1: fuzzy name so we don't know, we don't paint ourselves

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Speaker 1: in the corner, which hey, maybe that was wise.

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Speaker 4: Oh yeah, so maybe after they figured out what it was,

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Speaker 4: they should have called it like straight up stellar objects,

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Speaker 4: like we're totally sure about this.

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Speaker 1: But they're not stars, right, they're not stars, So it

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Speaker 1: was good that they left.

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Speaker 3: That fuzz Oh so stellar means star, not just like spacey.

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Speaker 1: Yes, exactly, like a star.

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Speaker 3: Yeah, yeah, Kelly is really good with words.

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Speaker 1: All right, Moving on, and they knew it was that

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Speaker 1: they had a very small angular size, right, like they

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Speaker 1: could tune the radio telescopes in a certain direction and

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Speaker 1: see it and then turn it a little further away

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Speaker 1: and not see it right, and so you could tell

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Speaker 1: that this thing was coming from a localized spot in

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Speaker 1: the sky. And by the sixties there were like hundreds

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Speaker 1: of these things had been cataloged, and so people started

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Speaker 1: a dedicated search for like, let's look to see if

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Speaker 1: we can find something that corresponds to them. And then

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Speaker 1: in the early sixties they finally found one. They found

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Speaker 1: like a what looked like a faint star right at

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Speaker 1: the location of the radio source, but the spectrum of

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Speaker 1: it didn't really make sense. It was very confusing to understand,

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Speaker 1: like what this object was.

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Speaker 3: What was it? It was a quasar? Then what is

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Speaker 3: a quasar?

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Speaker 1: And what is a quasar? That was the question, right,

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Speaker 1: So first thing they just look at the spectrum and

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Speaker 1: they noticed, like the spectrum implies that it's really really

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Speaker 1: really red shifted, meaning that it's really really far away.

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Speaker 1: Because remember, as we look out into space, we're not

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Speaker 1: just looking back in time. We're looking at things moving

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Speaker 1: away from us. Hubble's big discovery was that the further

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Speaker 1: away something is the faster it seems to be moving

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Speaker 1: away from us. And so if you find something which

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Speaker 1: is super red shifted, meaning it's moving away from us

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Speaker 1: very fast, that also means it's super distant. And that

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Speaker 1: was one of the early puzzles. It's like, Okay, we're

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Speaker 1: seeing this star. It's not super bright, but it's crazy

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Speaker 1: far away, which means that at its source it's got

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Speaker 1: to be like insanely bright for us to see it.

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Speaker 1: These things were apparently like most of the way across

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Speaker 1: the universe, and yet somehow we were still seeing them.

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Speaker 1: So people were like, wow, what this doesn't make sense

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Speaker 1: if our calculations are correct. There's an incredible source of

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Speaker 1: energy being shot at us from across the universe. How

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Speaker 1: can that be right?

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Speaker 3: Yeah? How can that be right? It's like a murder mystery.

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Speaker 3: I'm waiting for the end.

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Speaker 1: Yeah, exactly. And so you have this combination of like

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Speaker 1: extreme velocity and distance, yet we're able to see it.

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Speaker 1: And this implies some intense source of power, right, you

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Speaker 1: need something in order to generate something to make these

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Speaker 1: things brighter. Essentially, it would have to be like a

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Speaker 1: thousand times brighter than the entire Milky Way for us

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Speaker 1: to see it across the universe, so we're talking like

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Speaker 1: three billion light years away, and so the early explanation

439
00:21:16,080 --> 00:21:20,119
Speaker 1: was that you have an active galactic nuclei. So the

440
00:21:20,560 --> 00:21:22,840
Speaker 1: centers of the galaxies are not just like here's a

441
00:21:22,840 --> 00:21:25,560
Speaker 1: bunch of stars all swirling around and they're just sort

442
00:21:25,600 --> 00:21:28,160
Speaker 1: of denser than they are out here, but that there's

443
00:21:28,240 --> 00:21:31,560
Speaker 1: something else going on. And this is essentially at the

444
00:21:31,600 --> 00:21:34,800
Speaker 1: same time as we're starting to understand, hey, are black

445
00:21:34,840 --> 00:21:37,800
Speaker 1: holes are real thing. They're not just like a calculation

446
00:21:37,880 --> 00:21:40,560
Speaker 1: that Einstein and his friends did, are like an actual

447
00:21:40,640 --> 00:21:43,800
Speaker 1: thing out there in the universe. And so this all

448
00:21:43,840 --> 00:21:47,359
Speaker 1: came together into this cohesive explanation that the center of

449
00:21:47,400 --> 00:21:51,400
Speaker 1: the galaxy is very dense gravitationally, and you have these

450
00:21:51,400 --> 00:21:55,080
Speaker 1: super massive black holes at their cores, and the gravity

451
00:21:55,160 --> 00:21:58,880
Speaker 1: of that super massive black hole combined with its magnetic field,

452
00:21:59,280 --> 00:22:01,800
Speaker 1: is generating these astrophysical jets.

453
00:22:02,119 --> 00:22:05,120
Speaker 4: Okay, so a quasar is the center of a galaxy

454
00:22:05,160 --> 00:22:06,720
Speaker 4: where you have a black hole and all of that

455
00:22:06,840 --> 00:22:08,640
Speaker 4: denseness and stuff is shooting out.

456
00:22:08,640 --> 00:22:11,400
Speaker 1: Yes, exactly as seen from Earth. So like you could

457
00:22:11,440 --> 00:22:13,159
Speaker 1: describe it in several ways. You could say you have

458
00:22:13,200 --> 00:22:16,800
Speaker 1: an active galactic nucleus, which is generating these jets from Earth.

459
00:22:16,880 --> 00:22:19,439
Speaker 1: If you see it, you call it a quasar, and

460
00:22:19,480 --> 00:22:21,560
Speaker 1: so it's sort of the union of these things as

461
00:22:21,600 --> 00:22:22,840
Speaker 1: seen from different angles.

462
00:22:23,040 --> 00:22:25,600
Speaker 3: So does every galaxy have a quasar?

463
00:22:26,119 --> 00:22:30,360
Speaker 1: No, every galaxy does not necessarily have a quasar. It's fascinating.

464
00:22:30,440 --> 00:22:35,200
Speaker 1: Not every galaxy has an active nucleus, right, It's really interesting.

465
00:22:35,359 --> 00:22:37,680
Speaker 4: And is that because not every galaxy has a black

466
00:22:37,720 --> 00:22:40,680
Speaker 4: hole at its center? Maybe, or this is a different reason.

467
00:22:40,880 --> 00:22:42,959
Speaker 1: We don't know. It's a real mystery. It seems like

468
00:22:43,000 --> 00:22:46,080
Speaker 1: the universe made a lot of quasars about ten billion

469
00:22:46,240 --> 00:22:49,880
Speaker 1: years ago, and since then it hasn't been making very

470
00:22:49,880 --> 00:22:52,479
Speaker 1: many of them. So like that's why most of them

471
00:22:52,560 --> 00:22:55,600
Speaker 1: are far away, Like there aren't quasars that are like

472
00:22:55,800 --> 00:22:59,960
Speaker 1: quasaring right now nearby, Like the Andromeda doesn't have a quake,

473
00:23:00,080 --> 00:23:03,560
Speaker 1: so Heart doesn't have massive bright pulls of plasma shooting

474
00:23:03,560 --> 00:23:05,960
Speaker 1: out from both sides of it. You have to look

475
00:23:06,000 --> 00:23:08,280
Speaker 1: further away, which implies it was in the past. So

476
00:23:08,400 --> 00:23:11,280
Speaker 1: there was something in the conditions of the universe ten

477
00:23:11,320 --> 00:23:15,399
Speaker 1: billion years ago which was really quasari, and it's no longer.

478
00:23:15,640 --> 00:23:17,280
Speaker 1: Is the universe very quasari.

479
00:23:17,640 --> 00:23:20,320
Speaker 4: It's like the fashion of the universe, like neon leggings

480
00:23:20,320 --> 00:23:22,879
Speaker 4: were big in the eighties and quasars were big at someway,

481
00:23:22,960 --> 00:23:26,040
Speaker 4: but both went out of style. Yeah exactly, but the

482
00:23:26,119 --> 00:23:28,080
Speaker 4: leggings are coming back. Maybe quasars come.

483
00:23:28,040 --> 00:23:33,000
Speaker 1: There nostalgia for the early universe. I don't know. These

484
00:23:33,040 --> 00:23:37,520
Speaker 1: things are dangerous, right, so it's crazy. The oldest quasar

485
00:23:37,600 --> 00:23:41,919
Speaker 1: we've seen comes from a galaxy we visualized six hundred

486
00:23:41,920 --> 00:23:45,200
Speaker 1: and ninety million years after the Big Bang, so that's

487
00:23:45,320 --> 00:23:48,879
Speaker 1: less than a billion years after you know, the first

488
00:23:48,920 --> 00:23:52,280
Speaker 1: atoms are formed, and then finally stars are formed, and

489
00:23:52,320 --> 00:23:55,840
Speaker 1: then galaxies come together, and already you have the conditions

490
00:23:55,880 --> 00:23:59,080
Speaker 1: necessary to create a quasar. And this is one of

491
00:23:59,080 --> 00:24:01,919
Speaker 1: the bigger puzzles in the early universe recently, is like

492
00:24:02,000 --> 00:24:04,560
Speaker 1: how things got so big so fast? You know, how

493
00:24:04,600 --> 00:24:06,679
Speaker 1: did you get super massive black holes at the centers

494
00:24:06,680 --> 00:24:09,880
Speaker 1: of galaxies so quickly after the beginning of the universe.

495
00:24:09,960 --> 00:24:14,280
Speaker 1: Our simulations can't explain that. James Webspace Telescope, which looks

496
00:24:14,280 --> 00:24:17,399
Speaker 1: in their infrared, can see super distant, super old stuff

497
00:24:17,440 --> 00:24:21,879
Speaker 1: and it's visualized galactic formation that nobody understands either. Like

498
00:24:22,080 --> 00:24:24,199
Speaker 1: very early in the universe, you have galaxies that are

499
00:24:24,320 --> 00:24:27,200
Speaker 1: much bigger than anything we can understand. So this is

500
00:24:27,240 --> 00:24:29,400
Speaker 1: a core question, and it's like, how does stuff come

501
00:24:29,440 --> 00:24:32,560
Speaker 1: together and form structure in the early universe so quickly.

502
00:24:32,840 --> 00:24:35,119
Speaker 1: There's definitely an element there that we don't understand in

503
00:24:35,160 --> 00:24:37,760
Speaker 1: Quasars are a big part of that. Why did they

504
00:24:37,760 --> 00:24:40,040
Speaker 1: come up in the early universe? Why aren't they making

505
00:24:40,080 --> 00:24:40,840
Speaker 1: them anymore?

506
00:24:41,040 --> 00:24:43,040
Speaker 4: Why did they go out of style like the fashion

507
00:24:43,080 --> 00:24:45,160
Speaker 4: in the eighties, which I would say was a really

508
00:24:45,160 --> 00:24:48,199
Speaker 4: good era. So okay, so the jets are different than

509
00:24:48,240 --> 00:24:51,280
Speaker 4: the quasars. The jets come out of the quasars, and

510
00:24:51,359 --> 00:24:53,679
Speaker 4: so why are the quasars making the jets?

511
00:24:53,960 --> 00:24:56,240
Speaker 1: Yeah, I would say quasars are the thing we see

512
00:24:56,240 --> 00:24:58,800
Speaker 1: from Earth, right, Okay, the jets are the sort of

513
00:24:58,880 --> 00:25:02,760
Speaker 1: underlying physical process says that generates our observation of the quasar.

514
00:25:03,160 --> 00:25:05,240
Speaker 1: But you're right, it's a good question. What is making

515
00:25:05,280 --> 00:25:08,640
Speaker 1: these jets. They're super bright, they're super intense. We think

516
00:25:08,680 --> 00:25:12,320
Speaker 1: they're powered by this active galactic nuclei and fundamentally the

517
00:25:12,359 --> 00:25:15,680
Speaker 1: black holes at their cores. Right, these are super massive

518
00:25:15,800 --> 00:25:19,359
Speaker 1: black holes. And remember black holes come in two categories.

519
00:25:19,400 --> 00:25:22,280
Speaker 1: There's like there's a star that burned up all of

520
00:25:22,320 --> 00:25:25,800
Speaker 1: its fuel, and the fusion is no longer providing pressure

521
00:25:25,880 --> 00:25:28,120
Speaker 1: to keep that star puffed up, and so the gravity

522
00:25:28,119 --> 00:25:30,080
Speaker 1: eventually wins and it collapses and you get a black

523
00:25:30,080 --> 00:25:32,000
Speaker 1: hole that's going to give you a black hole up

524
00:25:32,080 --> 00:25:35,200
Speaker 1: to like fifty eighty maybe one hundred times the mass

525
00:25:35,200 --> 00:25:37,560
Speaker 1: of our Sun. But the black holes are the centers

526
00:25:37,560 --> 00:25:41,199
Speaker 1: of galaxies. These things are like millions or billions of

527
00:25:41,240 --> 00:25:43,800
Speaker 1: times the mass of the Sun. So definitely not the

528
00:25:43,840 --> 00:25:47,000
Speaker 1: collapse of an individual star, and again a big mystery

529
00:25:47,040 --> 00:25:50,560
Speaker 1: as to how they form. But they're enormously massive, and

530
00:25:50,600 --> 00:25:52,680
Speaker 1: they're at the centers of these galaxies, and we think

531
00:25:52,720 --> 00:25:56,360
Speaker 1: that the gravitational energy of these black holes, as well

532
00:25:56,359 --> 00:26:00,000
Speaker 1: as their spin, is what's powering these astrophysical jets.

533
00:26:00,160 --> 00:26:03,720
Speaker 4: All right, So as a biologist, yeah, it's counterintuitive to

534
00:26:03,720 --> 00:26:05,280
Speaker 4: me because I feel like the main thing I know

535
00:26:05,359 --> 00:26:08,000
Speaker 4: about black holes is that they like suck things in

536
00:26:08,200 --> 00:26:09,200
Speaker 4: if it gets close enough.

537
00:26:09,320 --> 00:26:11,040
Speaker 3: Yeah, and so now we're talking.

538
00:26:10,760 --> 00:26:14,280
Speaker 4: About stuff getting seemingly spit out of black holes.

539
00:26:14,320 --> 00:26:16,399
Speaker 3: So what bridge the gap there for me?

540
00:26:16,560 --> 00:26:19,200
Speaker 1: Yeah, it's a good question. And remember that black holes

541
00:26:19,240 --> 00:26:22,880
Speaker 1: are super gravitational and powerful, but they're not magical right there,

542
00:26:22,960 --> 00:26:26,080
Speaker 1: just like suck everything in. You can, for example, orbit

543
00:26:26,080 --> 00:26:28,040
Speaker 1: a black hole the way you can orbit the Sun,

544
00:26:28,280 --> 00:26:30,680
Speaker 1: because a gravity from a black hole is just gravity.

545
00:26:31,080 --> 00:26:32,879
Speaker 1: So if you're at the right velocity and at the

546
00:26:32,960 --> 00:26:35,720
Speaker 1: right radius, you can orbit a black hole forever. It's

547
00:26:35,760 --> 00:26:38,760
Speaker 1: not going to magically suck you in. So let's think

548
00:26:38,800 --> 00:26:41,360
Speaker 1: about how black holes are the centers of galaxies work. Well,

549
00:26:41,359 --> 00:26:44,000
Speaker 1: you have the black hole, then you have stuff swirling

550
00:26:44,080 --> 00:26:47,080
Speaker 1: around it, right, so that stuff could in principle stay

551
00:26:47,119 --> 00:26:50,320
Speaker 1: in orbit forever. So just because it's near the black

552
00:26:50,359 --> 00:26:53,200
Speaker 1: hole doesn't mean it's going to get sucked in necessarily.

553
00:26:53,920 --> 00:26:55,840
Speaker 1: And that's why you have like this accretion disc. If

554
00:26:55,880 --> 00:26:57,720
Speaker 1: you think about your image of a black hole, it's

555
00:26:57,760 --> 00:27:00,280
Speaker 1: not just like a black sphere. It's like a disc

556
00:27:00,359 --> 00:27:02,960
Speaker 1: of stuff that's orbiting around it. That's the stuff that's

557
00:27:03,000 --> 00:27:05,679
Speaker 1: like on deck for going into the black hole. Hasn't

558
00:27:05,720 --> 00:27:08,960
Speaker 1: fallen in yet, all right, So why does it actually

559
00:27:08,960 --> 00:27:11,840
Speaker 1: fall in. It falls in because there's friction. Like if

560
00:27:11,880 --> 00:27:14,679
Speaker 1: you're just orbiting a black hole or a star, you

561
00:27:14,680 --> 00:27:18,120
Speaker 1: could do that forever. But if you and ten trillion

562
00:27:18,160 --> 00:27:21,119
Speaker 1: of your friends are all orbiting a star, you're gonna

563
00:27:21,119 --> 00:27:24,159
Speaker 1: bump into each other, and occasionally somebody's gonna get nudged

564
00:27:24,200 --> 00:27:26,639
Speaker 1: into the center right out of orbit. That's what an

565
00:27:26,640 --> 00:27:30,000
Speaker 1: accretion disk is. It's like a huge cloud of gas

566
00:27:30,000 --> 00:27:32,719
Speaker 1: and dust and little bits, and there's friction between them.

567
00:27:32,720 --> 00:27:35,240
Speaker 1: They bump into each other, they pull on each other gravitationally,

568
00:27:35,440 --> 00:27:37,639
Speaker 1: so some of the stuff falls in. All right, So

569
00:27:37,720 --> 00:27:40,720
Speaker 1: particles are now falling in towards the black hole. But

570
00:27:41,119 --> 00:27:46,199
Speaker 1: black holes also have magnetic fields. They're not just gravitational objects.

571
00:27:47,040 --> 00:27:50,119
Speaker 1: And what do magnetic fields do? They bend the path

572
00:27:50,160 --> 00:27:53,560
Speaker 1: of charge particles. Think about particles coming from the Sun

573
00:27:53,800 --> 00:27:56,879
Speaker 1: towards the Earth. What happens to them? They don't just

574
00:27:57,080 --> 00:27:59,760
Speaker 1: hit us down here on the Earth. They get deflected

575
00:27:59,760 --> 00:28:02,879
Speaker 1: by the magnetic field, and they get deflected towards the

576
00:28:02,880 --> 00:28:05,480
Speaker 1: North pole and towards the South pole, and some of them,

577
00:28:05,480 --> 00:28:07,680
Speaker 1: because the magnetic field is different at the north pole,

578
00:28:08,000 --> 00:28:10,160
Speaker 1: go in at the atmosphere there, which is what causes

579
00:28:10,240 --> 00:28:13,400
Speaker 1: the Northern lights or the Southern lights. Those are super

580
00:28:13,480 --> 00:28:16,360
Speaker 1: high energy particles from space hitting the atmosphere and then

581
00:28:16,440 --> 00:28:20,440
Speaker 1: glowing gorgeous. Yeah, and so just like the Earth has

582
00:28:20,520 --> 00:28:24,040
Speaker 1: gravity but also has a magnetic field. Particles falling into

583
00:28:24,080 --> 00:28:27,200
Speaker 1: the blank hole will get deflected up towards the north

584
00:28:27,200 --> 00:28:29,520
Speaker 1: pole or the south pole because of the super intense

585
00:28:29,600 --> 00:28:32,040
Speaker 1: magnetic field, and so they get sped up by the

586
00:28:32,080 --> 00:28:34,680
Speaker 1: gravitational field and then they get bent by the magnetic

587
00:28:34,720 --> 00:28:37,440
Speaker 1: field and then shot up or down the poles.

588
00:28:37,640 --> 00:28:37,920
Speaker 3: Ah.

589
00:28:37,960 --> 00:28:40,840
Speaker 4: Okay, so everything that's getting shot out then has some charge.

590
00:28:41,000 --> 00:28:43,320
Speaker 1: Yes, almost everything here is going to be charged, because

591
00:28:43,520 --> 00:28:45,840
Speaker 1: it's very hard to stay neutral. Like if you have

592
00:28:45,920 --> 00:28:49,400
Speaker 1: protons and electrons and they're in hydrogen atom, the energy

593
00:28:49,400 --> 00:28:51,880
Speaker 1: of that bond is tiny compared to the energy of

594
00:28:51,920 --> 00:28:55,160
Speaker 1: these particles, and so they're just going to blow apart. Right,

595
00:28:55,160 --> 00:28:58,520
Speaker 1: So basically everything is plasma here. Everything is charged, and

596
00:28:58,600 --> 00:29:00,760
Speaker 1: so you get plasma. They gets sho up and down

597
00:29:00,800 --> 00:29:03,880
Speaker 1: the north and south poles, and plasma itself glows. So

598
00:29:03,920 --> 00:29:06,920
Speaker 1: where do the photons come from? Right? Photons come from

599
00:29:06,920 --> 00:29:10,240
Speaker 1: these particles getting bent by the magnetic fields. Because how

600
00:29:10,280 --> 00:29:13,480
Speaker 1: does a charge particle change direction? Every time a charge

601
00:29:13,480 --> 00:29:16,680
Speaker 1: particle change direction, it emits a photon. That's the only

602
00:29:16,720 --> 00:29:18,400
Speaker 1: way you can do it. Can't just be like I'm

603
00:29:18,440 --> 00:29:21,040
Speaker 1: going this way, now I'm going that way. And the

604
00:29:21,080 --> 00:29:23,240
Speaker 1: way it does it is by emitting a photon. It's

605
00:29:23,240 --> 00:29:25,239
Speaker 1: like I'm going straight, I'm gonna go right. I'm going

606
00:29:25,280 --> 00:29:27,800
Speaker 1: to admit a photon for the left. Therefore I'm going

607
00:29:27,840 --> 00:29:30,200
Speaker 1: to recoil against it to the right. Just like if

608
00:29:30,240 --> 00:29:32,840
Speaker 1: you're flying through space and you want to change direction,

609
00:29:32,920 --> 00:29:35,040
Speaker 1: what do you do? You fire your rockets and you

610
00:29:35,320 --> 00:29:38,239
Speaker 1: shoot some stuff out in the opposite direction that you

611
00:29:38,280 --> 00:29:40,800
Speaker 1: want to go. Charge particles have to do that also,

612
00:29:41,360 --> 00:29:43,760
Speaker 1: and they shoot out photons. They have like an infinite

613
00:29:43,840 --> 00:29:47,040
Speaker 1: supply of photons inside of them. You can imagine. They

614
00:29:47,080 --> 00:29:49,760
Speaker 1: don't literally have all those photons. They just you know,

615
00:29:49,880 --> 00:29:53,560
Speaker 1: dump some of their energy into the electromagnetic field with

616
00:29:53,720 --> 00:29:56,480
Speaker 1: momentum the opposite direction that they need to go, and

617
00:29:56,520 --> 00:29:58,200
Speaker 1: so then they go that way. And there's nobody like

618
00:29:58,320 --> 00:30:00,880
Speaker 1: driving these particles. I'm making them sound like they're making

619
00:30:00,920 --> 00:30:04,400
Speaker 1: these decisions, but this is just the process anyway. So

620
00:30:04,800 --> 00:30:08,480
Speaker 1: stuff falls in towards the center gets routed towards the

621
00:30:08,520 --> 00:30:11,320
Speaker 1: poles using a magnetic field, and that's how you get

622
00:30:11,360 --> 00:30:14,320
Speaker 1: these jets. And the power comes from the gravitational energy

623
00:30:14,640 --> 00:30:15,440
Speaker 1: of the black hole.

624
00:30:15,720 --> 00:30:19,920
Speaker 4: So the centers of galaxies that have astrophysical jets are

625
00:30:20,240 --> 00:30:23,320
Speaker 4: only the centers of galaxies that have a black hole

626
00:30:23,400 --> 00:30:26,000
Speaker 4: in the middle. Is that fair to say because you

627
00:30:26,040 --> 00:30:27,440
Speaker 4: need the black hole's magnetic field.

628
00:30:27,560 --> 00:30:32,000
Speaker 1: Yeah, exactly, And that's because almost every single galaxy has

629
00:30:32,040 --> 00:30:34,320
Speaker 1: a super massive black hole at its heart. OK, So

630
00:30:34,360 --> 00:30:35,840
Speaker 1: that's pretty safe to say anyway.

631
00:30:36,040 --> 00:30:38,320
Speaker 3: And do all black holes make these jets?

632
00:30:38,520 --> 00:30:41,120
Speaker 1: Yeah, that's a great question. And so some of these

633
00:30:41,240 --> 00:30:44,560
Speaker 1: active galactic nuclei have all the conditions we think for

634
00:30:44,720 --> 00:30:47,200
Speaker 1: making a jet, but they don't have jets. Right, there's

635
00:30:47,240 --> 00:30:51,200
Speaker 1: a big, powerful black hole there, there's a swirling mass

636
00:30:51,200 --> 00:30:53,920
Speaker 1: of gas and dust and particles, but there's no jet.

637
00:30:54,400 --> 00:30:56,400
Speaker 1: And so, as you said earlier, this is not something

638
00:30:56,480 --> 00:30:59,880
Speaker 1: we currently understand, and there's a lot of current research

639
00:31:00,080 --> 00:31:03,920
Speaker 1: on like understanding the magnetic environment around a black hole,

640
00:31:03,960 --> 00:31:05,720
Speaker 1: because it's fun to even think about, Like, well, why

641
00:31:05,760 --> 00:31:10,200
Speaker 1: do black holes have magnetic fields? Anyway? Aren't they gravitational objects?

642
00:31:10,520 --> 00:31:10,960
Speaker 3: Yeah?

643
00:31:11,520 --> 00:31:11,800
Speaker 2: Why?

644
00:31:13,920 --> 00:31:16,440
Speaker 1: Black holes are really weird things. And there's only three

645
00:31:16,520 --> 00:31:19,520
Speaker 1: things that they can have. They can have a mass, right,

646
00:31:19,560 --> 00:31:22,040
Speaker 1: you can put stuff into a black hole and it grows,

647
00:31:22,040 --> 00:31:25,000
Speaker 1: so it's mass increases. But they can also have an

648
00:31:25,040 --> 00:31:27,920
Speaker 1: electric charge, right, Like what happens if you have a

649
00:31:27,920 --> 00:31:31,080
Speaker 1: black hole and it's neutral. And you drop an electron

650
00:31:31,120 --> 00:31:33,520
Speaker 1: into a black hole, well, now it has a charge.

651
00:31:33,560 --> 00:31:36,720
Speaker 1: Because the universe serves electric charge. It can't just eat

652
00:31:36,800 --> 00:31:39,640
Speaker 1: the electric charge and then boom, it's gone. You've deleted

653
00:31:39,640 --> 00:31:42,719
Speaker 1: it from the universe. The universe conserves electric charge. So

654
00:31:43,160 --> 00:31:45,560
Speaker 1: if you drop an electron into a black hole, we

655
00:31:45,560 --> 00:31:47,560
Speaker 1: don't know what happens to the electron. Is it's still

656
00:31:47,600 --> 00:31:50,239
Speaker 1: an electron, whatever, is it something else? But we do

657
00:31:50,400 --> 00:31:53,680
Speaker 1: know that that charge is now added to the event horizon.

658
00:31:54,400 --> 00:31:56,320
Speaker 1: So we don't know what's going on inside the black hole,

659
00:31:56,360 --> 00:31:58,760
Speaker 1: but you can think of the event horizon itself now

660
00:31:58,920 --> 00:31:59,880
Speaker 1: as charged.

661
00:32:00,240 --> 00:32:02,840
Speaker 4: So do most black holes have a negative or a

662
00:32:02,920 --> 00:32:05,280
Speaker 4: positive charge? Or is it like split fifty to fifty?

663
00:32:05,360 --> 00:32:07,680
Speaker 4: What is the predominant charge of black holes?

664
00:32:07,920 --> 00:32:11,560
Speaker 1: Yeah, great question. Most black holes have either a positive

665
00:32:11,640 --> 00:32:14,040
Speaker 1: or a negative charge. It's about split fifty to fifty.

666
00:32:14,080 --> 00:32:16,480
Speaker 1: We think we haven't measured this in detail for any

667
00:32:16,480 --> 00:32:20,440
Speaker 1: black holes. But you know, imagine that you randomly throw

668
00:32:20,520 --> 00:32:23,520
Speaker 1: in positive and negative particles and you do it a

669
00:32:23,520 --> 00:32:26,240
Speaker 1: billion times. In order for the black hole to be neutral,

670
00:32:26,440 --> 00:32:29,400
Speaker 1: those would have to be exactly equal. It's like flipping

671
00:32:29,400 --> 00:32:32,920
Speaker 1: a coin a trillion times and getting exactly half of

672
00:32:32,960 --> 00:32:34,960
Speaker 1: them to be heads and exactly half of them to

673
00:32:35,000 --> 00:32:38,360
Speaker 1: be tailed very very unlikely. So we think there probably

674
00:32:38,400 --> 00:32:41,959
Speaker 1: are no electrically neutral black holes in the universe. Probably

675
00:32:42,000 --> 00:32:44,400
Speaker 1: every black hole out there has some charge because it's

676
00:32:44,400 --> 00:32:47,840
Speaker 1: eaten positives and negatives, and the chances that they add

677
00:32:47,920 --> 00:32:51,320
Speaker 1: up exactly to zero basically zero. So now you have

678
00:32:51,360 --> 00:32:54,160
Speaker 1: a black hole has gravity, has mass, and it has

679
00:32:54,200 --> 00:32:56,880
Speaker 1: electric charge. There's one more thing black holes can have,

680
00:32:57,120 --> 00:33:01,920
Speaker 1: which is spin, because the universe also conserve angular momentum. Right,

681
00:33:02,400 --> 00:33:05,440
Speaker 1: momentum is just like if you're moving through space. Newton

682
00:33:05,480 --> 00:33:08,520
Speaker 1: tells us that you can't just move without something pushing

683
00:33:08,600 --> 00:33:12,720
Speaker 1: you or this conservation of momentum. Well, spin is also conserved.

684
00:33:12,720 --> 00:33:15,880
Speaker 1: If you like set something spinning in space, it'll spin forever.

685
00:33:16,520 --> 00:33:18,280
Speaker 1: The only way to stop is to come with some

686
00:33:18,440 --> 00:33:21,240
Speaker 1: external torque. Same thing is true if you drop something

687
00:33:21,240 --> 00:33:24,000
Speaker 1: into a black hole instead of just dropping an object

688
00:33:24,040 --> 00:33:26,440
Speaker 1: straight in imagine if you drop an object so it

689
00:33:26,480 --> 00:33:28,560
Speaker 1: hits the black hole like sort of near the edge,

690
00:33:28,920 --> 00:33:31,320
Speaker 1: sort of like spinning a bicycle wheel right, pushing on

691
00:33:31,400 --> 00:33:33,760
Speaker 1: the edge to make it spin rather than poking it

692
00:33:33,800 --> 00:33:36,719
Speaker 1: in the center. Same thing. If you drop an object

693
00:33:36,800 --> 00:33:38,760
Speaker 1: into a black hole, you can make it spin, and

694
00:33:38,800 --> 00:33:41,400
Speaker 1: it conserves that spin. The universe can't just get rid

695
00:33:41,440 --> 00:33:44,360
Speaker 1: of angular momentum. So now you have an object which

696
00:33:44,360 --> 00:33:47,440
Speaker 1: has an electric charge and it has to spin. What

697
00:33:47,600 --> 00:33:48,320
Speaker 1: happens with that?

698
00:33:48,600 --> 00:33:50,200
Speaker 3: You've got a magnetic field.

699
00:33:50,480 --> 00:33:57,440
Speaker 1: Boom, Oh my gosh, congratulations exactly. And because magnetic fields

700
00:33:57,440 --> 00:34:00,600
Speaker 1: are not generated by magnetic charges, we don't know if

701
00:34:00,640 --> 00:34:03,840
Speaker 1: monopoles exist in the universe. Right, the only way to

702
00:34:03,840 --> 00:34:06,240
Speaker 1: make a magnetic field in our universe is to combine

703
00:34:06,400 --> 00:34:11,360
Speaker 1: electric charges and motion. So currents generated magnetic fields. Spinning

704
00:34:11,480 --> 00:34:16,200
Speaker 1: objects generated magnetic fields. So black holes have magnetic fields.

705
00:34:16,239 --> 00:34:18,160
Speaker 1: And this is fun to think about. The way I

706
00:34:18,280 --> 00:34:20,960
Speaker 1: visualize it is that I put the charge and spin

707
00:34:21,080 --> 00:34:23,839
Speaker 1: on the event horizon. We don't know what's going on inside,

708
00:34:24,280 --> 00:34:26,000
Speaker 1: so you don't have to worry about like, how is

709
00:34:26,040 --> 00:34:29,600
Speaker 1: the information getting from inside the black hole to the outside.

710
00:34:29,640 --> 00:34:34,160
Speaker 1: Just imagine a spinning sphere of charge and that generates

711
00:34:34,200 --> 00:34:37,359
Speaker 1: a magnetic field. The event horizon is conceptually similar to that.

712
00:34:37,560 --> 00:34:41,359
Speaker 4: Okay, so all black holes. It sounds like all black

713
00:34:41,400 --> 00:34:43,719
Speaker 4: holes should have magnetic fields, because probably none of them

714
00:34:43,719 --> 00:34:47,040
Speaker 4: are neutral. Exactly, but they don't all make the jets.

715
00:34:47,160 --> 00:34:49,360
Speaker 4: Is that because some of them have stronger magnetic fields

716
00:34:49,400 --> 00:34:51,799
Speaker 4: than others or we really don't know.

717
00:34:52,160 --> 00:34:55,200
Speaker 1: We really don't know. Yeah, it's a mystery active galactic

718
00:34:55,320 --> 00:34:59,080
Speaker 1: nuclei hot area of research and definitely not something we understand.

719
00:35:00,120 --> 00:35:03,480
Speaker 1: You know, when they do this, it's really dramatic. One

720
00:35:03,560 --> 00:35:05,879
Speaker 1: other way to study these things is not to look

721
00:35:05,920 --> 00:35:08,160
Speaker 1: for the active galactic nuclei, but to try to study

722
00:35:08,200 --> 00:35:10,960
Speaker 1: the black holes and their magnetic fields in more detail.

723
00:35:11,640 --> 00:35:14,480
Speaker 1: And so, for example, we have image black holes, a

724
00:35:14,520 --> 00:35:17,239
Speaker 1: couple of them, right, Remember these pictures that look like

725
00:35:17,239 --> 00:35:20,200
Speaker 1: a Crispy Kreme donut of the accretion disk around a

726
00:35:20,239 --> 00:35:23,960
Speaker 1: black hole. Super awesome from the event Horizon telescope. That's

727
00:35:24,000 --> 00:35:26,600
Speaker 1: the stuff that's swirling around the black hole, waiting on

728
00:35:26,719 --> 00:35:29,480
Speaker 1: deck maybe to go in. Well, a few years after

729
00:35:29,560 --> 00:35:32,440
Speaker 1: they released that image, they released a follow up image

730
00:35:32,680 --> 00:35:36,000
Speaker 1: where they studied the magnetic field lines near the black hole.

731
00:35:36,280 --> 00:35:39,719
Speaker 1: By looking at the polarization of the photons that come

732
00:35:39,760 --> 00:35:42,600
Speaker 1: from different parts of the accretion disc, they can understand

733
00:35:42,640 --> 00:35:46,480
Speaker 1: the magnetic fields and polarization of photons is kind of weird.

734
00:35:46,880 --> 00:35:50,239
Speaker 1: It's because photons are vector objects. They're not just like

735
00:35:50,680 --> 00:35:52,880
Speaker 1: a location in space. They also have like a direction,

736
00:35:53,000 --> 00:35:56,440
Speaker 1: and so they can essentially spin as they move. And

737
00:35:56,800 --> 00:35:59,799
Speaker 1: so photons have like this little vector extra vector that

738
00:35:59,800 --> 00:36:01,920
Speaker 1: you can measure. We don't have to dick into the

739
00:36:01,920 --> 00:36:05,160
Speaker 1: details now, but we are studying the polarization of these

740
00:36:05,160 --> 00:36:07,759
Speaker 1: photons that come from the vicinity of black holes and

741
00:36:07,760 --> 00:36:12,040
Speaker 1: trying to understand which models of magnetic fields in the

742
00:36:12,120 --> 00:36:15,520
Speaker 1: vicinity of black holes make the most sense best agree

743
00:36:15,560 --> 00:36:17,520
Speaker 1: with the data with what we see out there in

744
00:36:17,560 --> 00:36:18,280
Speaker 1: the universe.

745
00:36:18,560 --> 00:36:20,560
Speaker 4: Cool, all right, So let's take a break. And we've

746
00:36:20,560 --> 00:36:24,319
Speaker 4: talked about astrophysical jets, and I realized that in my head,

747
00:36:24,360 --> 00:36:27,480
Speaker 4: I've decided that that is what relativistic beaming means.

748
00:36:28,080 --> 00:36:30,759
Speaker 3: But maybe that's not actually true. So let Daniel shake

749
00:36:30,760 --> 00:36:31,239
Speaker 3: in his head.

750
00:36:31,239 --> 00:36:49,480
Speaker 4: No, so let's clear up Kelly's misconceptions after the break.

751
00:36:54,440 --> 00:36:58,120
Speaker 4: All right, So, astro physical jets are those things that

752
00:36:58,200 --> 00:37:00,960
Speaker 4: get shot out of quasars that have black holes, but

753
00:37:01,040 --> 00:37:02,040
Speaker 4: not all of them.

754
00:37:02,320 --> 00:37:03,759
Speaker 3: And I thought that.

755
00:37:03,760 --> 00:37:07,680
Speaker 4: This resulted in relativistic beaming, like the beam that comes

756
00:37:07,680 --> 00:37:09,279
Speaker 4: out of the center is But no, you.

757
00:37:09,640 --> 00:37:12,960
Speaker 3: Shook your head. No, So what is relativistic beaming Daniel.

758
00:37:13,200 --> 00:37:16,840
Speaker 1: Yes, so we have these astrophysical jets. We understand something

759
00:37:16,840 --> 00:37:19,719
Speaker 1: about how they're made. They're extraordinarily powerful. We used to

760
00:37:19,800 --> 00:37:22,640
Speaker 1: call them quasars when we saw them in the sky,

761
00:37:22,800 --> 00:37:25,080
Speaker 1: and we see them all over the universe. There's lots

762
00:37:25,080 --> 00:37:28,600
Speaker 1: of them that we spotted. We've I think identified seven

763
00:37:28,680 --> 00:37:32,520
Speaker 1: hundred and fifty thousand different quasars in the umbers, which

764
00:37:32,560 --> 00:37:35,000
Speaker 1: is a lot. Most of them are not pointed at

765
00:37:35,080 --> 00:37:37,359
Speaker 1: us right, so we can see them even if they're

766
00:37:37,400 --> 00:37:39,560
Speaker 1: not pointed at us. And the most dramatic pictures you'll

767
00:37:39,560 --> 00:37:42,120
Speaker 1: see online are ones we see sort of from the side.

768
00:37:42,560 --> 00:37:44,600
Speaker 1: We can see them from the side because they emit photons.

769
00:37:44,640 --> 00:37:47,279
Speaker 1: Also from the side, they hit each other and they glow,

770
00:37:47,320 --> 00:37:49,960
Speaker 1: et cetera, et cetera. But the brightest ones are the

771
00:37:50,000 --> 00:37:53,400
Speaker 1: ones pointed right at us. Like if there's a galaxy

772
00:37:53,480 --> 00:37:57,560
Speaker 1: out there that's oriented perfectly, so we're looking exactly at

773
00:37:57,600 --> 00:38:00,600
Speaker 1: the plane of the galaxy and the core of the

774
00:38:00,680 --> 00:38:04,680
Speaker 1: nuclei is pointed like directly at the Earth, then those

775
00:38:04,840 --> 00:38:08,160
Speaker 1: particles are shooting exactly towards us when they're emitted from

776
00:38:08,160 --> 00:38:11,920
Speaker 1: the galaxy, and then they benefit from a super awesome

777
00:38:12,360 --> 00:38:17,080
Speaker 1: extra special boost that makes that galactic core even brighter

778
00:38:17,360 --> 00:38:21,200
Speaker 1: than it otherwise would be. And that's relativistic beaming.

779
00:38:21,680 --> 00:38:24,080
Speaker 4: Ah, okay, So it's not brighter just because it's pointing

780
00:38:24,120 --> 00:38:25,479
Speaker 4: at us, making it easier to see.

781
00:38:25,520 --> 00:38:26,920
Speaker 3: It's brighter for some other reason.

782
00:38:27,080 --> 00:38:29,440
Speaker 1: That's right. It is brighter because it's pointing at us,

783
00:38:29,480 --> 00:38:32,160
Speaker 1: and that makes it easier to see. But plus it

784
00:38:32,160 --> 00:38:36,040
Speaker 1: gets souped up because of this relativistic effect, which you

785
00:38:36,080 --> 00:38:38,840
Speaker 1: could also consider to just be like the relativistic version

786
00:38:38,960 --> 00:38:42,439
Speaker 1: of the Doppler effect. Right, anything that's moving towards you

787
00:38:42,680 --> 00:38:45,399
Speaker 1: is going to get blue shifted. Anything moving away from

788
00:38:45,440 --> 00:38:48,000
Speaker 1: you is going to get red shifted. And it's easy

789
00:38:48,080 --> 00:38:50,279
Speaker 1: to understand that. It's something we experience every day. If

790
00:38:50,280 --> 00:38:53,399
Speaker 1: you hear a police car drive by you, you hear

791
00:38:53,560 --> 00:38:57,520
Speaker 1: the sound that its siren makes changes as it passes you. Right,

792
00:38:57,840 --> 00:39:00,279
Speaker 1: when it's approaching, it's a higher sound. When it's moving away,

793
00:39:00,320 --> 00:39:03,640
Speaker 1: it's a lower sound. Why is that. It's because the

794
00:39:03,719 --> 00:39:07,279
Speaker 1: wavelength gets shifted to longer wavelengths when it's moving away

795
00:39:07,320 --> 00:39:10,280
Speaker 1: from you. Right. If you just imagine, like a source

796
00:39:10,560 --> 00:39:13,400
Speaker 1: moving away from you, it's going to draw out longer

797
00:39:13,440 --> 00:39:15,879
Speaker 1: wavelengths than a source moving towards you, and so each

798
00:39:15,920 --> 00:39:19,400
Speaker 1: wavelength is a little bit shorter. That's a generic Doppler effect.

799
00:39:19,440 --> 00:39:21,759
Speaker 1: Things moving away from us are red shifted, which is

800
00:39:21,800 --> 00:39:24,799
Speaker 1: also how we can infer distance because there's a relationship

801
00:39:24,800 --> 00:39:27,520
Speaker 1: between red shift and distance. In the universe, things moving

802
00:39:27,560 --> 00:39:29,799
Speaker 1: towards us are blue shifted, and we see this in

803
00:39:29,840 --> 00:39:31,759
Speaker 1: the sky like not everything in the sky is moving

804
00:39:31,800 --> 00:39:35,760
Speaker 1: away from us, Andrameda, for example, is overcoming the expansion

805
00:39:35,800 --> 00:39:38,360
Speaker 1: of the universe and local gravity is pulling it towards us.

806
00:39:38,400 --> 00:39:42,440
Speaker 1: So Andromeda in the sky is blue shifted, not red shifted. Okay,

807
00:39:42,480 --> 00:39:45,920
Speaker 1: so that's the Doppler effect, which is something fairly well known.

808
00:39:46,040 --> 00:39:50,000
Speaker 1: But special relativity changes everything. Right, normal Doppler effect is

809
00:39:50,000 --> 00:39:52,600
Speaker 1: what happens when things are pretty slow and not moving

810
00:39:52,640 --> 00:39:55,920
Speaker 1: super fast, like the way I move here on Earth. Right,

811
00:39:56,000 --> 00:39:57,560
Speaker 1: especially now that I'm fifty years old.

812
00:39:57,800 --> 00:39:59,280
Speaker 3: You're a spry fifty Daniel.

813
00:40:00,760 --> 00:40:06,480
Speaker 1: Thank you. Astro Physically speaking, I'm quite yes, these quasars

814
00:40:06,520 --> 00:40:10,880
Speaker 1: make me feel like a spring chicken. But when relativity

815
00:40:10,880 --> 00:40:14,120
Speaker 1: comes into play, things change, and astrophysical jets are moving

816
00:40:14,160 --> 00:40:16,600
Speaker 1: near the speed of light relative to us, and so

817
00:40:16,680 --> 00:40:21,560
Speaker 1: they benefit from the relativistic Doppler effect, which super enhances

818
00:40:21,600 --> 00:40:25,080
Speaker 1: the brightness in the direction of motion the energy of

819
00:40:25,160 --> 00:40:28,320
Speaker 1: these things in the direction of motion. For two reasons.

820
00:40:29,000 --> 00:40:35,000
Speaker 7: Reason one and reason number one is our old friend,

821
00:40:35,400 --> 00:40:38,240
Speaker 7: length contraction, and the rule of thumb for length contraction

822
00:40:38,480 --> 00:40:40,600
Speaker 7: is moving objects seem shorter.

823
00:40:41,160 --> 00:40:42,719
Speaker 1: So if you're just like looking at a ruler and

824
00:40:42,760 --> 00:40:45,000
Speaker 1: it's sitting next to you, you measure it's a meter long.

825
00:40:45,800 --> 00:40:48,440
Speaker 1: If instead it's zooming towards you at nine tenths the

826
00:40:48,480 --> 00:40:50,680
Speaker 1: speed of light, and then you measure it, you're not

827
00:40:50,719 --> 00:40:52,759
Speaker 1: going to measure it to be a meter long. You're

828
00:40:52,760 --> 00:40:54,479
Speaker 1: going to measure it to be less than a meter.

829
00:40:54,840 --> 00:40:58,600
Speaker 1: Moving objects are shorter, and that's a super fun and

830
00:40:58,800 --> 00:41:02,600
Speaker 1: mind bending consequence special relativity which I love thinking about.

831
00:41:02,800 --> 00:41:05,360
Speaker 1: And people often ask me like, well, why is it shorter?

832
00:41:06,040 --> 00:41:08,440
Speaker 1: And you know, I think that's a really revealing question

833
00:41:08,600 --> 00:41:12,359
Speaker 1: because the answer is it only actually makes sense for

834
00:41:12,440 --> 00:41:15,440
Speaker 1: it to be shorter in the universe, where the speed

835
00:41:15,440 --> 00:41:17,719
Speaker 1: of light is fixed for all observers, it has to

836
00:41:17,760 --> 00:41:20,480
Speaker 1: be shorter. It wouldn't actually make sense to measure that

837
00:41:21,000 --> 00:41:23,719
Speaker 1: meter stick as a meter if it's moving. But our

838
00:41:23,719 --> 00:41:27,360
Speaker 1: intuition is that speed shouldn't change the length of things.

839
00:41:27,880 --> 00:41:30,520
Speaker 1: Kelly thinks, Oh, and my daughter's running across the yard.

840
00:41:30,560 --> 00:41:32,799
Speaker 1: She's the same person, in the same size as she

841
00:41:32,880 --> 00:41:35,279
Speaker 1: was when she was standing still, and mostly she is

842
00:41:35,440 --> 00:41:38,480
Speaker 1: almost she is you can't tell, which is what gives

843
00:41:38,560 --> 00:41:42,600
Speaker 1: us this intuitive feeling that length shouldn't depend on velocity.

844
00:41:42,920 --> 00:41:46,440
Speaker 1: But we're wrong. It actually does. There's no good reason

845
00:41:46,560 --> 00:41:49,880
Speaker 1: why length shouldn't depend on velocity. So this question, like

846
00:41:50,280 --> 00:41:54,040
Speaker 1: why does length depend on velocity, reveals again just our

847
00:41:54,200 --> 00:41:57,719
Speaker 1: bias towards things we find intuitive. If I told you, oh,

848
00:41:57,960 --> 00:42:00,959
Speaker 1: the length doesn't depend on velocity, you wouldn't ask me why.

849
00:42:01,120 --> 00:42:05,279
Speaker 1: You should just be like, yeah, yeah, cool. Anyway, that's

850
00:42:05,360 --> 00:42:08,640
Speaker 1: a digression on the special relativity. But in this case,

851
00:42:08,680 --> 00:42:11,239
Speaker 1: what's happening is the thing is shooting right at us,

852
00:42:11,320 --> 00:42:14,560
Speaker 1: moving very very high speeds. Right. So from the point

853
00:42:14,600 --> 00:42:17,839
Speaker 1: of view of that object, the distance between it and

854
00:42:17,920 --> 00:42:20,879
Speaker 1: the Earth is contracted, right because it sees the Earth

855
00:42:20,960 --> 00:42:24,239
Speaker 1: moving towards it at really high speeds, right, So we're

856
00:42:24,239 --> 00:42:27,440
Speaker 1: seeing it as if it was closer, right. So relativity

857
00:42:27,520 --> 00:42:30,280
Speaker 1: is like shrinking the distance between us and the center

858
00:42:30,320 --> 00:42:33,239
Speaker 1: of this galaxy. This furnace where the black hole is

859
00:42:33,239 --> 00:42:35,160
Speaker 1: shooting bullets at us at super high speed.

860
00:42:35,320 --> 00:42:37,480
Speaker 3: It's bringing us closer to that, and that's what makes

861
00:42:37,520 --> 00:42:37,960
Speaker 3: it brighter.

862
00:42:38,040 --> 00:42:40,000
Speaker 1: That's one of the things that makes it brighter. It's

863
00:42:40,160 --> 00:42:43,720
Speaker 1: reason number one. And that's why it's called relativistic beaming

864
00:42:43,760 --> 00:42:47,400
Speaker 1: because it's like, the relativistic Doppler effect is making this

865
00:42:47,520 --> 00:42:49,520
Speaker 1: much brighter if it's pointed at you.

866
00:42:49,640 --> 00:42:51,560
Speaker 4: That's amazing that we figured that out, because you'd look

867
00:42:51,600 --> 00:42:53,160
Speaker 4: out at the sky and you'd be like, some quasers

868
00:42:53,160 --> 00:42:54,000
Speaker 4: are brighter than the other.

869
00:42:54,080 --> 00:42:56,600
Speaker 3: But like to account for that anyway, go.

870
00:42:56,560 --> 00:42:58,719
Speaker 1: Humans, And that's why I started this episode with, like,

871
00:42:58,960 --> 00:43:01,600
Speaker 1: to understand this, you got to understand gravity of black holes,

872
00:43:01,600 --> 00:43:03,960
Speaker 1: you got to understand magnetism of the bending, and then

873
00:43:04,000 --> 00:43:06,879
Speaker 1: you've got to bring in the relativity to show why

874
00:43:06,920 --> 00:43:08,120
Speaker 1: these things are so bright.

875
00:43:08,400 --> 00:43:11,920
Speaker 3: So many blocks, all right? Reason two.

876
00:43:12,400 --> 00:43:15,880
Speaker 1: Reason number two is the other fun bit of special relativity,

877
00:43:15,880 --> 00:43:19,400
Speaker 1: which is time dilation. Right, So special relativity tells us

878
00:43:19,480 --> 00:43:23,520
Speaker 1: that moving objects look shorter, but also that moving clocks

879
00:43:23,880 --> 00:43:27,440
Speaker 1: run more slowly. Right, And so what's happening when you

880
00:43:27,560 --> 00:43:32,160
Speaker 1: look at Equasar is relativity changes the frequency of these things. Right,

881
00:43:32,200 --> 00:43:34,680
Speaker 1: We talked about how you go from red shift or

882
00:43:34,680 --> 00:43:38,680
Speaker 1: blue shift depending on the velocity. Well, changing the color,

883
00:43:38,800 --> 00:43:42,680
Speaker 1: changing the frequency also changes the energy, right, And so

884
00:43:42,840 --> 00:43:46,640
Speaker 1: if these things are blue shifted, that makes them more energetic.

885
00:43:47,160 --> 00:43:49,040
Speaker 1: So the particles are not just pointed at us, the

886
00:43:49,120 --> 00:43:51,800
Speaker 1: moving at us at very high speed, and relativity boosts

887
00:43:51,880 --> 00:43:55,160
Speaker 1: that to make them have more energy in our frame.

888
00:43:55,640 --> 00:43:57,600
Speaker 1: And that's a confusing thing to think about, like how

889
00:43:57,600 --> 00:44:01,080
Speaker 1: does relativity give something more energy? Remember that energy is

890
00:44:01,080 --> 00:44:03,640
Speaker 1: conserved in a static universe. It's not actually conserved in

891
00:44:03,680 --> 00:44:08,600
Speaker 1: our expanding universe, but it's not invariant, meaning like I

892
00:44:08,640 --> 00:44:10,920
Speaker 1: can measure the energy of something and you can measure

893
00:44:10,920 --> 00:44:13,400
Speaker 1: the energy to be different. If your daughter is running

894
00:44:13,440 --> 00:44:15,840
Speaker 1: past you on the lawn, you measured her to have

895
00:44:15,840 --> 00:44:18,640
Speaker 1: a certain velocity a certain kinetic energy. If your husband

896
00:44:18,719 --> 00:44:21,319
Speaker 1: is running next to her, he says, no, she's not

897
00:44:21,400 --> 00:44:23,799
Speaker 1: moving at all. She has no energy. So you two

898
00:44:23,880 --> 00:44:27,120
Speaker 1: can disagree on how much energy she has. Because energy

899
00:44:27,160 --> 00:44:30,440
Speaker 1: is frame dependent, we think it's conserved in a static universe,

900
00:44:30,440 --> 00:44:33,600
Speaker 1: but it's not invariant, which often leads to confusion. So

901
00:44:33,640 --> 00:44:36,480
Speaker 1: you and I can disagree about how much energy something has,

902
00:44:36,520 --> 00:44:39,319
Speaker 1: and the energy of these astrophysical jest depends on the

903
00:44:39,360 --> 00:44:43,440
Speaker 1: observer because energy is frame dependent. It's relative, it's not

904
00:44:43,520 --> 00:44:44,680
Speaker 1: an absolute quantity.

905
00:44:45,000 --> 00:44:48,160
Speaker 4: Okay, Okay, So while you were describing this, I realize that.

906
00:44:48,239 --> 00:44:53,480
Speaker 4: So we're talking about charged particles moving super fast towards us.

907
00:44:54,080 --> 00:44:56,400
Speaker 4: Is this s galactic cosmic radiation? Is this what the

908
00:44:56,440 --> 00:44:57,760
Speaker 4: astronauts have to worry about?

909
00:44:57,840 --> 00:45:00,480
Speaker 1: This is one source of that. Absolutely. Yeah. And when

910
00:45:00,520 --> 00:45:03,600
Speaker 1: you're out there in space near the ISS, for example,

911
00:45:04,080 --> 00:45:06,520
Speaker 1: this is one of those elements. You're absolutely right. It's

912
00:45:06,560 --> 00:45:08,960
Speaker 1: a dangerous environment. And that partially comes from the Sun,

913
00:45:09,080 --> 00:45:12,840
Speaker 1: and partially comes from inside our galaxy, and partially comes

914
00:45:12,840 --> 00:45:16,839
Speaker 1: from other galaxies. We think the highest energy ones come

915
00:45:16,880 --> 00:45:18,640
Speaker 1: from the centers of other galaxies.

916
00:45:18,760 --> 00:45:21,560
Speaker 4: WHOA, Okay, so I should be saying that galactic cosmic

917
00:45:21,640 --> 00:45:23,680
Speaker 4: radiation comes from quasars.

918
00:45:23,760 --> 00:45:25,480
Speaker 3: No from astrophysical.

919
00:45:24,880 --> 00:45:27,720
Speaker 1: Jets or quasars. Yeah, either one works, okay.

920
00:45:27,760 --> 00:45:30,360
Speaker 3: And they're super bright because of relativistic beaming.

921
00:45:30,520 --> 00:45:34,120
Speaker 1: Yes, absolutely, they're super bright even without the relativistic beaming.

922
00:45:34,360 --> 00:45:37,040
Speaker 1: But then they're super double extra bright because of the

923
00:45:37,080 --> 00:45:39,560
Speaker 1: relativistic beaming. The ones that are pointed right at us

924
00:45:39,840 --> 00:45:44,080
Speaker 1: gets super enhanced because of these relativistic effects. So it's

925
00:45:44,080 --> 00:45:47,080
Speaker 1: this incredible dance of all these pieces of physics, and

926
00:45:47,120 --> 00:45:49,680
Speaker 1: it took us decades to put this all together, and

927
00:45:49,760 --> 00:45:52,600
Speaker 1: so many different branches of physics and so many different

928
00:45:52,840 --> 00:45:55,840
Speaker 1: historical traditions came together for us to like start to

929
00:45:55,920 --> 00:45:59,440
Speaker 1: understand a coherent picture of what's going on inside galaxies

930
00:45:59,440 --> 00:46:02,719
Speaker 1: and such an important thread in science, you know, is

931
00:46:02,880 --> 00:46:06,160
Speaker 1: understanding things from different perspectives and like making sure the

932
00:46:06,200 --> 00:46:09,120
Speaker 1: story you're telling is coherent when you come at it

933
00:46:09,120 --> 00:46:12,759
Speaker 1: from different angles, and that's often how we unravel mysteries. Right,

934
00:46:12,800 --> 00:46:14,400
Speaker 1: We're like, well, this seems to work, but wait, what

935
00:46:14,480 --> 00:46:17,040
Speaker 1: about this piece? If I measure differently or if I

936
00:46:17,160 --> 00:46:19,760
Speaker 1: come out from this angle, it's not making sense. Because

937
00:46:19,800 --> 00:46:22,640
Speaker 1: we think, we hope the universe does make sense and

938
00:46:22,680 --> 00:46:24,600
Speaker 1: that there is a story out there that we can

939
00:46:24,680 --> 00:46:26,879
Speaker 1: unravel no matter how you look at it.

940
00:46:26,960 --> 00:46:29,120
Speaker 4: And I really love human story, So let me tell

941
00:46:29,239 --> 00:46:31,640
Speaker 4: an astronaut story really quick. So when I was reading

942
00:46:31,800 --> 00:46:35,239
Speaker 4: astronaut memoirs, there's a lot of times where they'll talk

943
00:46:35,239 --> 00:46:38,200
Speaker 4: about like being in space and then like a flash

944
00:46:38,239 --> 00:46:41,480
Speaker 4: of light, it's like it passes through their eyeballs and

945
00:46:42,080 --> 00:46:43,839
Speaker 4: they were kind of not sure what it was. It's

946
00:46:43,880 --> 00:46:46,279
Speaker 4: probably kind of a scary experience. And I think that

947
00:46:46,360 --> 00:46:50,160
Speaker 4: the main hypothesis to explain what's happening is that galactic

948
00:46:50,200 --> 00:46:53,080
Speaker 4: cosmic radiation is passing through your eyeballs and it like

949
00:46:53,480 --> 00:46:56,319
Speaker 4: lights up, you know, the receptors in your eye, and

950
00:46:56,360 --> 00:46:59,120
Speaker 4: that's what you see. It's kind of scary and yeah,

951
00:46:59,480 --> 00:47:03,439
Speaker 4: one super scary too. Kind of amazing though, to think that.

952
00:47:03,520 --> 00:47:06,800
Speaker 3: Your vision is being impacted by something happening in a

953
00:47:06,880 --> 00:47:09,759
Speaker 3: quasar and a distant galaxy.

954
00:47:10,360 --> 00:47:13,800
Speaker 4: Anyway, What a crazy universe we live in. Also, I

955
00:47:13,960 --> 00:47:15,000
Speaker 4: like it down here on Earth.

956
00:47:17,080 --> 00:47:18,640
Speaker 1: I know it is nice to live here beneath the

957
00:47:18,680 --> 00:47:21,520
Speaker 1: shelter of our magnetic field and our atmosphere, yeah, where

958
00:47:21,560 --> 00:47:24,919
Speaker 1: our eyeballs are not getting pelted by bullets shot out

959
00:47:24,920 --> 00:47:27,440
Speaker 1: by black holes from other very distinct galaxies.

960
00:47:27,480 --> 00:47:30,080
Speaker 3: Thank you magnetic fields protecting our Earth.

961
00:47:32,080 --> 00:47:35,359
Speaker 1: Thank you our fragile environment. And thanks to everybody out

962
00:47:35,360 --> 00:47:37,799
Speaker 1: there for being curious about how the universe works and

963
00:47:37,840 --> 00:47:41,200
Speaker 1: listening to this explanation for how the centers of distant

964
00:47:41,280 --> 00:47:47,279
Speaker 1: galaxies combined gravity, electromagnetism, and relativity to shoot particles at you.

965
00:47:47,760 --> 00:47:48,880
Speaker 3: See, y'all, next time.

966
00:47:55,800 --> 00:47:59,360
Speaker 4: Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio.

967
00:47:59,520 --> 00:48:01,080
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968
00:48:01,200 --> 00:48:04,120
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969
00:48:04,360 --> 00:48:06,960
Speaker 1: have about this Extraordinary Universe.

970
00:48:07,080 --> 00:48:10,000
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971
00:48:10,040 --> 00:48:11,000
Speaker 4: for future shows.

972
00:48:11,120 --> 00:48:13,480
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973
00:48:13,719 --> 00:48:17,279
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974
00:48:17,320 --> 00:48:20,520
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975
00:48:19,560 --> 00:48:21,640
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976
00:48:21,760 --> 00:48:25,560
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977
00:48:25,640 --> 00:48:26,600
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978
00:48:26,600 --> 00:48:29,560
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979
00:48:29,760 --> 00:48:31,319
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