Kind: captions
Language: en
LIGO, this experiment which detected two
black holes in orbit around each other
which then collided and merged into one
big black hole and it was like mallets
banging on a drum. The whole of spaceime
literally space and time ringing and the
ringing
>> emanated through the universe in the
particular case of our discovery.
>> What was it? Uh a billion and a half
years.
Do I have that number? I don't know.
first one. I feel like that's right.
>> It's a billion and a half light years
away.
>> Yeah. Wow.
>> Like multisellularity was underway on
the earth.
>> Oh my goodness.
>> Right. Right.
>> And I mean that's happening all over.
But this was the one that we were on
this collision course with it.
>> That is
>> and you know humans evolve.
>> Einstein comes around and it's at a
neighboring star system. It's still on
its way here ringing. Space's ringing.
>> If these gravitational waves are
emanating from these black holes
colliding,
Are they escaping from inside the black
hole?
>> Yeah, that's a great question. They are
not escaping from inside the black hole.
It is ringing space outside the black
holes. However, the sum, the final black
hole,
>> yes,
>> has a mass that's less than the sum of
the two black holes. The E= MC² energy.
Yeah.
>> The mass that's lost is all pumped into
these gravitational waves. Wow. So the
30 something solar mass black hole and
the 20some solar mass black hole when
they merge.
>> Yeah.
>> That black hole is a little lighter
>> than the sum of those two masses.
>> And are we talking
>> all of that energy E= MC² energy as we
know from nuclear bombs right is huge.
So all of that energy was something like
three solar masses of energy is
enormous. And that means that that event
was the most powerful event um human
beings have recorded since the big bang.
>> Wow.
>> Um 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.
>> So how many of these things have they
discovered now? Well, now if the
instrument were operating all the time,
kind of monthly
>> be like one a month we say.
>> Wow.
>> Kind of monthly. And and and um 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 the mass of
the sun, only 10 times. Like that's a
good kind of canonical
>> 10. 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 it's not what
happened.
>> So we got black holes are big. Yeah.
>> Yeah. Do we have hundreds or thousands
of times in in terms of these
collisions?
>> I would say well so in principle they're
happening all the time. They're just too
far away.
>> So we're kind of saying out to the
distance we can we can detect. I don't
want to say see because none of it comes
out as light. Right.
>> Right. All of this comes out in the ring
in the black holes. It's complete
darkness.
>> Jeez. So, it's one of the rare
experiments in astronomy where we're not
talking about a telescope collecting
light. It's completely different.
>> So, here's a question. If it's emitting
all that energy, like three solar masses
of energy,
>> yeah,
>> it may not be doing it in all directions
equally. So, could it just like
>> Yeah.
>> create a jet of gravitational energy and
fly off?
>> You do have to think about the
orientation of the orbital plane,
>> you know? So they're orbiting around
each other and there's a plane it what
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 um there's some ambiguity in
trying to ter determine things like
that.
>> Well I guess the question I was getting
at though is does the new black hole
that formed
>> by the emitting all this gravitational
wave energy could that gravitational
wave energy propel it to turn into a
black hole that just shoots down? 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.
>> Holy cow. So, out of nowhere.
>> Yeah. I mean, it, you know, it maybe
came in, it would it all depends on the
orbits, just like the mallets on the
drum. If you swirl them around, it makes
a certain sound. It's very,
>> you know, 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. And then
you'll hear it kind of bing bing bing
bing bing bing. Um so so yes, we can
kind of 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. The black hole just starts to
kind of wander around the galaxy,
but once it happens, it goes quiet. Uh
once it forms,
>> so you get no more data.
>> So there's actually something really
deep about this question of this ringing
down. So when the the event horizons
merge like this bubble of ink and
bobbles down and then goes quiet that's
because uh something very profound about
black holes and that is that they they
cannot tolerate any imperfections
>> and and that's actually a deep point. So
we've been talking about tolerate
>> they cannot tolerate any imperfection.
If you took Mount Everest and you tried
to put it
>> I've dated a black hole once in my
youth. It was
>> Yeah.
>> Haven't we all? No.
>> Um or I was ever I don't know. But if so
you put Mount Everest on the event
horizon uh 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 um and that is
the event horizon says you can know
nothing about the interior of a black
hole,
>> right? You cannot know anything about
it. If that bump remained, you would
know more about it than you should be
allowed to.
>> Oh, is this so principle?
>> Black holes have no hair.
>> 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
establish that kind of by definition
right by definition. So that means that
I can't come up to a black hole a
billion years after its formation and
deduce ah that was a blue star because
that would mean somehow information was
coming out of the interior and and no
information could come out of that
interior.
>> But why is that such a big thing? Why?
Oh, well, okay. So, there's Oh, there's
there's there's several reasons why it's
a deep thing, but in 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,
>> right?
>> I can know its mass and I can know its
spin.
>> Yes,
>> that's it.
>> That's it.
>> That's my whole list, right? Yeah.
>> So the reason why that's so profound is
it means it's not like anything else in
the universe which can
>> which can have flaws
>> and features right so even a neutron
star can have tiny tiny they're very
tiny tiny tiny little features I could
say oh that's my neutron star
>> right
>> I put a flag on it I went to the moon I
put a flag on it the moon has this big
crater it has these 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.
>> Two black holes.
>> Mhm.
>> That had the same mass, charge, and
spin.
>> You cannot tell the difference.
>> And I did the cup game.
>> There's no meaning to saying which one's
which. It's worse than saying, "Ah,
that's, you know, 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 uh they are
indistinguishable in the same way that
an electron is indistinguishable
from every other electron in the
universe. One electron is not a little
bit heavier. You can't say, "Oh, that's,
you know, that was my electron that I
sloughed off, you know, this morning."
um they're so identical that they're
technically interchangeable in a very
profound way because we think that
they're a fundamental particle of
nature. So there's something fundamental
about the electron. It's indivisible,
>> right? And um and it cannot be a little
faster spin, a little heavier.