Particles of Thought

JANNA:

LIGO, this experiment which detected two black holes and orbit around each other, which then collided and merged into one big black hole and it was like mallets banging on a drum. The hole of space-time, literally space and time ringing.

HAKEEM (00:26:40):

Just [inaudible 00:26:41], yeah.

JANNA (00:26:40):

And the ringing emanated the universe. In the particular case of our discovery, what was it? A billion and a half years? Do I have that number right?

HAKEEM (00:26:52):

The first one? I don't know.

JANNA (00:26:53):

The first one. I feel like that's right.

HAKEEM (00:26:55):

Wow. It's a billion and a half light years away?

JANNA (00:26:56):

Yeah.

HAKEEM (00:26:56):

Wow.

JANNA (00:26:58):

Multicellularity was underway on the Earth.

HAKEEM (00:27:00):

Oh my goodness.

JANNA (00:27:02):

Right?

HAKEEM (00:27:02):

Yeah, yeah, right.

JANNA (00:27:03):

And I mean, that's happening all over but this was the one that we were on this collision course with it.

HAKEEM (00:27:08):

That is something.

JANNA (00:27:08):

And humans evolve. Einstein comes around and it's at a neighboring star system, it's still on its way here, ringing space-time's ringing. By the time-

HAKEEM (00:27:20):

So Einstein showed up just in enough time for us to see it.

JANNA (00:27:23):

For us to detect this one. And by the time they built the detector, and they-

HAKEEM (00:27:29):

Well, go into it because I don't think the people may know what LIGO is.

JANNA (00:27:33):

Yeah. So LIGO is a Laser Interferometric Gravitational Wave Observatory. It is a very cumbersome name. You don't even need to know, just LIGO to its friends.

HAKEEM (00:27:45):

Just the mirrors and lasers.

JANNA (00:27:47):

To its friends. It's an enormous instrument. It's shaped like an L and it shines light down these long vacuum tubes, four kilometers long on each side. And what it's really doing, I liken it to a musical instrument. What it's really doing is it's delicately bouncing these mirrors so that if a wave passes in the space itself, the mirrors will like bob with the wave and then the distance traveled along the two directions is going to be modulated by this bobbling. And the entire experiment is designed to detect motions like that of less than a ten-thousandth the width of an atom across four kilometers.

HAKEEM (00:28:26):

Oh, wow.

JANNA (00:28:27):

It was the most stunning engineering achievement. I mean, even if it hadn't detected anything, it would've been really sad, but as an engineering achievement.

HAKEEM (00:28:35):

That is nuts.

JANNA (00:28:35):

It was tremendous, it took 50 years.

HAKEEM (00:28:37):

Wow.

JANNA (00:28:38):

And so you imagine that when they finally installed the advanced components of this detector, they'd been running for 15 years with an initial detector that detected nothing. Crickets, right?

HAKEEM (00:28:49):

Geez.

JANNA (00:28:49):

But they knew it wasn't sensitive enough. They keep pushing. 15 years later, it's now 50 years after it began, 100 years since Einstein first proposed these waves in the shape of space-time.

HAKEEM (00:28:59):

Holy cow.

JANNA (00:29:00):

It was a centenary. Some guys are working on a machine, experimentalists on two different sites. In the middle of the night they decided they weren't ready for the science run. They're working to the wee hours in the morning. They get besides themselves, they decide it's time to go home. They mercifully leave the instrument locked, but they drive away [inaudible 00:29:23].

HAKEEM (00:29:23):

Was it still on?

JANNA (00:29:24):

It was still on. Locked meaning ready for detection, not offline. And this wave washes over the site in Louisiana. It travels at the speed of light until it washes over the site in Washington state. And the instrument rings. Literally, they would listen to the instrument in the control room. Honestly, if it had struck a couple hours earlier, they would've been messing with the instrument too much to have made this detection.

HAKEEM (00:29:51):

Oh, I see.

JANNA (00:29:51):

It's only the first detection. It's not like it was the only event in the universe. It was just the one that fate would have, we were on a collision course with. Right? And so it detects this ring, it's incredibly fast. It happens in milliseconds and it's incredibly, you would say, quiet. The signal has to be drastically amplified, but it does happen in the human auditory range.

HAKEEM (00:30:14):

No way.

JANNA (00:30:14):

The instrument, it's sensitive.

HAKEEM (00:30:16):

The frequency.

JANNA (00:30:16):

... to frequencies of the ringing of space-time that are the same as the piano.

HAKEEM (00:30:22):

Wow, wow. That's amazing.

JANNA (00:30:23):

And the piano is such a great instrument because it's like the human auditory range. That's why all musical theorists learn on the piano.

HAKEEM (00:30:30):

So, what notes are they then? So, does it go by mass like oh, if it's-

JANNA (00:30:36):

Yeah, just like you would think that the bigger the mass of the black hole, the lower the notes.

HAKEEM (00:30:41):

Oh, I see.

JANNA (00:30:42):

So there are some black holes that are so big and the collisions are at frequencies that we can't detect on earth. And there is a project called Lisa, which is proposed for space, which seems to be moving along.

HAKEEM (00:30:53):

So you have, instead of four kilometers, the distance is much longer?

JANNA (00:30:57):

Yeah, you can have millions of kilometers. And what you're doing, you're not actually having them physically connected. You're having nodes, which are just floating instruments that shine lasers between them through the empty space around in probably a heliocentric orbit. So it's orbiting the sun.

HAKEEM (00:31:14):

Wow. So a big triangle orbiting the sun?

JANNA (00:31:17):

A big triangle orbiting the sun. Yeah.

HAKEEM (00:31:18):

Man.

JANNA (00:31:18):

I mean, each three of the instruments are separately orbiting. Right?

HAKEEM (00:31:22):

Right, yeah, yeah.

JANNA (00:31:24):

But the point is, I kind of liken it to an electric guitar. If you think of how an electric guitar works, you pluck a string, the string rings at a certain frequency, but you don't really hear it very well.

HAKEEM (00:31:34):

What do you mean?

JANNA (00:31:35):

You have to put the amplifiers-

HAKEEM (00:31:38):

Oh, that's right. [inaudible 00:31:38].

JANNA (00:31:38):

It's electric, right?

HAKEEM (00:31:39):

That's right, yeah.

JANNA (00:31:39):

And the amplifier records the ringing and plays it back to you. And that is actually kind of how the instrument works. It's like it's a musical instrument. It's detecting the ringing of space, and then it's going through this incredibly elaborate process of amplifying it for you and playing it back to you.

HAKEEM (00:31:58):

So do now-

JANNA (00:31:59):

And you can listen to it.

HAKEEM (00:32:00):

Oh, really? So you go to a website?

JANNA (00:32:02):

It goes like... Yeah, that's what it sounds like. It's like, it's called a chirp.

HAKEEM (00:32:07):

So tell me this, can you tell what it is by the sound of the chirp?

JANNA (00:32:09):

It's a great question. Mathematically, there are these really interesting papers that say, can you hear the shape of a drum? So from the frequencies of the ringing space, can you deduce the shape of the drum? In this case, the analogy would really be the motion of the mallets.

HAKEEM (00:32:26):

I see.

JANNA (00:32:26):

The magnitude, the heft of the mallets, their mass and their motions. And the answer is, yeah, there are some that you can't tell one from the other, but you can absolutely-

HAKEEM (00:32:39):

So have they simulated it? So you can go and listen to, here's what this would sound like, here's what that would sound like?

JANNA (00:32:44):

Right. So the first one they detected, they could very quickly, and they've been working on this also for decades, this analysis. You give me the sound and I'll give you the black holes.

HAKEEM (00:32:53):

Oh, wow.

JANNA (00:32:53):

That's a hard, hard problem.

HAKEEM (00:32:55):

Wow.

JANNA (00:32:56):

Many, many groups worked on that for a very long time. So there are different groups who try to get overlapping results. That's one way that they know that they haven't just totally biased and they have a real detection. And so what they came back with was, we just heard the collision of two black holes. They were each around 30 times the mass of the sun one was a little bigger, one was a little smaller. So they're big, that's pretty big.

HAKEEM (00:33:18):

That's pretty big. Yeah.

JANNA (00:33:20):

30 times the mass of the sun. And they caught them in their final handful of orbits in a long, long life together. They might've been together for billions of years, solely spiraling together, banging space-time, losing energy, coming closer, getting faster. By the time they're that close together, they could be traveling at three quarters the speed of light and it's happening really fast.

HAKEEM (00:33:41):

Okay, so you just said something. So when I was in graduate school, one of the guys who won a Nobel Prize in my department was for this end spiral of black holes due to... Or I think it might've been even binary stars because they lose energy by emitting gravitational waves. So, those gravitational waves that are just emitted from the two things orbiting each other-

JANNA (00:34:07):

Binary, yes.

HAKEEM (00:34:08):

... we can't detect that?

JANNA (00:34:09):

No, and that's a really good question. We can detect that they're spiraling together and we can use that to deduce that we have calculated how much energy is being lost to these waves. And that was beautifully done, Nobel Prizes were involved with those.

HAKEEM (00:34:28):

Taylor and Hulse.

JANNA (00:34:29):

Yes, right, and then one of them was a pulsar, right?

HAKEEM (00:34:30):

Ah, one was a pulsar.

JANNA (00:34:32):

Hulse-Taylor Pulsar. Right? And-

HAKEEM (00:34:35):

Oh, that's how he did the timing?

JANNA (00:34:36):

That's why-

HAKEEM (00:34:41):

... Because it was a... So a pulsar is a neutron star that has a beam that points at you intermittently so you see beeps.

JANNA (00:34:45):

Right, right, right.

HAKEEM (00:34:45):

Right, right.

JANNA (00:34:48):

And it was an incredibly accurate determination but they didn't directly detect the gravitational waves themselves. And you're saying yeah, we can't detect those and we cannot, they're way too weak.

HAKEEM (00:34:57):

[inaudible 00:34:58].

JANNA (00:34:57):

This is part of gravity being weak. The Earth's pulling on us, but it's actually, I can beat the whole earth. I can jump. So, gravity is really weak.

HAKEEM (00:35:06):

But how would the frequency compare then? Would it be-

JANNA (00:35:08):

Too low and the amplitude-

HAKEEM (00:35:13):

Too low, yeah.

JANNA (00:35:14):

... just undetectable.

HAKEEM (00:35:15):

So the volume and the pitch

JANNA (00:35:19):

Are

HAKEEM (00:35:19):

Outside of the range of our instruments. Yeah.

JANNA (00:35:19):

Right, yeah, yeah. It's like exactly. The volume is, your volume knob is way too low. And even this was, this sensitivity that we're describing is required because it's still, by the time it gets here, it's so faint. If you were floating near those two black holes when they were colliding, it is conceivable that even in the vacuum of empty space, that your ear mechanism could ring in response.

HAKEEM (00:35:51):

Wow.

JANNA (00:35:51):

And you would hear it.

HAKEEM (00:35:51):

If you were close enough.

JANNA (00:35:51):

You would literally hear it, yeah.

HAKEEM (00:35:51):

It would move your... wow.

JANNA (00:35:52):

And your skull being less given to squeezing and stretching hopefully would resist, but you would hear it. Right? Because that's like... right, yeah.

HAKEEM (00:35:59):

Your brain would do that. Yeah. So here's something that comes to mind then. If these gravitational waves are emanating from these black holes colliding, are they escaping from inside the black holes?

JANNA (00:36:10):

Oh, it's a great question. They're not escaping from inside the black hole. It is ringing space outside the black holes. However, the sum, the final black hole has a mass that's less than the sum of the two black holes. The E=MC2 energy, the mass that's lost is all pumped into these gravitational waves.

HAKEEM (00:36:32):

Wow.

JANNA (00:36:33):

So the 30-something solar mass black hole and the 20-something solar mass black hole, when they merge, that black hole's a little lighter than the sum of those two masses.

HAKEEM (00:36:43):

And are we talking like-

JANNA (00:36:44):

And all of that energy, E=MC2 energy, as we know from nuclear bombs, is huge. So all of that energy, it was something like three solar masses of energy.

HAKEEM (00:36:54):

That's what I was going to ask, wow.

JANNA (00:36:55):

... is enormous. And that means that that event was the most powerful event human beings have recorded since the Big Bang.

HAKEEM (00:37:05):

Wow.

JANNA (00:37:06):

I mean, now there have been others, but the power in it was more than the power in all the light from all the stars in the observable universe combined.

HAKEEM (00:37:16):

So how many of these things have they discovered now?

JANNA (00:37:18):

Well now, if the instrument were operating all the time, monthly.

HAKEEM (00:37:24):

It'd be like one a month, give or take?

JANNA (00:37:25):

Right.

HAKEEM (00:37:25):

Wow.

JANNA (00:37:26):

Monthly. And the fact that they're so powerful, people didn't expect the black holes to be that big. So people worried, look, the black holes are going to be a few times to mask the sun only 10 times, that's a good kind of canonical tent. And so it's going to be hard to get anything loud enough to ring our instruments. They're going to have to be in real close, and we're going to have to get real lucky, but that's not what happened.

HAKEEM (00:37:50):

So we got dozens-

JANNA (00:37:51):

The black holes are big, yeah.

HAKEEM (00:37:52):

Yeah. Do we have hundreds or thousands of times, in terms of these collisions?

JANNA (00:37:56):

I would say, well, so in principle, they're happening all the time, they're just too far away. So we're seeing out to the distance we can detect, I don't want to say see, because none of it comes out as light.

HAKEEM (00:38:09):

Right.

JANNA (00:38:10):

Right? All of this comes out in the ring in the black holes, it's complete darkness.

HAKEEM (00:38:14):

Geez.

JANNA (00:38:14):

So it's one of the rare experiments in astronomy where we're not talking about a telescope collecting light. It's completely different.

HAKEEM (00:38:22):

So, here's a question. If it's emitting all that energy, like three solar masses of energy, it may not be doing it in all directions equally. So, could it just create a jet of gravitational energy and fly off?

JANNA (00:38:36):

Yeah, you do have to think about the orientation of the orbital plane. So they're orbiting around each other and there's a plane, the orientation of that plane relative to your line of sight or your line of detection in this case, and it does matter. It will change the signal. And so we also, there's some ambiguity in trying determine things like that.

HAKEEM (00:38:57):

Well, I guess the question I was getting at though is, does the new black hole that form by the emitting all this gravitational wave energy, could that gravitational wave energy propel it to turn-

JANNA (00:39:07):

Oh, it's a great question.

HAKEEM (00:39:07):

... into a black hole that just shoots in the galaxy?

JANNA (00:39:12):

Yeah, it can happen. So right, so it shoots so much energy in one direction the black hole starts to jettison. Black holes can be cruising along, yeah.

HAKEEM (00:39:18):

Holy cow. So, out of nowhere?

JANNA (00:39:21):

Yeah, I mean, it maybe came in... It all depends on the orbit. It's just like the mallets on the drum, if you swirl them around, it makes a certain sound. It's very eccentric, right? If it's looping, coming close and going back out again, it will be very different. It'll be like a knocking, it'll get quiet, it'll bang, it'll get quiet.

HAKEEM (00:39:38):

Oh, wow.

JANNA (00:39:38):

And then you'll hear it kind of bing, bing, bing, bing, bing.

HAKEEM (00:39:39):

Wow.

JANNA (00:39:41):

So yes, we can determine its orbital motion as well as the masses of the original black holes. And yeah, maybe sometimes there are these funny things that can happen where a lot of energy goes off in one direction and the black hole just starts to kind of wander around the galaxy. But once it happens, it goes quiet. Once it forms the-

HAKEEM (00:40:01):

Right. So you get no more data.

JANNA (00:40:02):

Right. So there's actually something really deep about this question of this ringing down. So when the event horizons emerge like this bubble of ink and bobbles down and then goes quiet, that's because something very profound about black holes. And that is that they cannot tolerate any imperfections, and that's actually a deep point. So we've been talking about-

HAKEEM (00:40:26):

They cannot tolerate.

JANNA (00:40:28):

They cannot tolerate any imperfection. If you took Mount Everest and you tried to put it.

HAKEEM (00:40:32):

I think I may have dated a black hole once in my youth. It was, yeah.

JANNA (00:40:32):

Yeah. Haven't we all? Or I was ever, I don't know. But if so you put Mount Everest on the event horizon, it won't tolerate that bump for long. Okay, it has to shake it off. And one way to see it is kind of philosophically to go back to my roots, which I disparaged, but. And that is the event horizon says you can know nothing about the interior of a black hole. Right? That you cannot know anything about it. If that bump remained, you would know more about it than you should be allowed to.

HAKEEM (00:41:12):

Oh, is this that so-called-

JANNA (00:41:13):

By the very principle.

HAKEEM (00:41:14):

... black holes have no hair idea?

JANNA (00:41:15):

Black holes have no hair. The idea it can't have stuff emanating out of it, which would tell you if you could trace the hair, it would tell you about properties on the inside. The event horizon really forbids the transmission of information from the interior of the black hole to the exterior. We kind of established that in the beginning.

HAKEEM (00:41:30):

That's kind by definition, right? So why is this a surprise?

JANNA (00:41:31):

Right, by definition. So that means that I can't come up to a black hole a billion years after its formation and deduce, oh, that was a blue star, because that would mean somehow information was coming out of the interior. And no information could come out of that interior. I means that information-

HAKEEM (00:41:48):

But why is that such a deep thing?

JANNA (00:41:49):

Oh, well, okay so there's-

HAKEEM (00:41:49):

... [inaudible 00:41:51] information.

JANNA (00:41:51):

Oh, there's several reasons why it's a deep thing. But in this context, I would say it's a deep thing because it means that there's something featureless about black holes. There are some things I can know about it. I can know its electric charge, I can know its mass, and I can know its spin. That's it.

HAKEEM (00:42:08):

That's it.

JANNA (00:42:10):

That's my whole list. Right? So the reason why that's so profound is it means it's not like anything else in the universe which can have flaws and features. Right? So even a neutron star can have tiny, tiny, and they're very tiny, tiny, tiny little features. I could say, oh, that's my neutron star. I put a flag on it, I went to the moon, I put a flag on it. The moon has this big crater, it's a specific moon and it's made up of this stuff. It means that black holes are so featureless that they're closer to fundamental particles than they are to astrophysical objects in that sense.

HAKEEM (00:42:50):

So if I had two black holes that had the same mass, charge, and spin-

JANNA (00:42:55):

You cannot tell their difference.

HAKEEM (00:42:56):

... and I did the cup game.

JANNA (00:42:57):

There's no meaning to saying which one's which.

HAKEEM (00:42:59):

You can't.

JANNA (00:42:59):

It's worse than saying, I tracked it in my mind, there's no meaning to saying this black hole is mine, or this was the one I marked, or... They are indistinguishable.

HAKEEM (00:43:13):

Wow.

JANNA (00:43:13):

In the same way that an electron is indistinguishable from every other electron-

HAKEEM (00:43:18):

That's right, yeah.

JANNA (00:43:19):

... in the universe. One electron's not a little bit heavier. You can't say, "Oh, that was my electron that I sloughed off this morning." They're so identical that they're technically interchangeable in a very profound way.

HAKEEM (00:43:30):

wow.

JANNA (00:43:31):

... because we think that they're a fundamental particle of nature. So there's something fundamental about the electron. It's indivisible, and it cannot be a little faster spin, a little heavier,