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I've come to Caltech because there is a brand new gravitational wave discovery.
Let's go find out what it is.
Can we talk about the discovery, Rana? -Yeah.
Can I-- I want to sit on one of my black holes. -Alright.
If you notice, this one's a big one
and that one's a little one. -This one is a little one. -Yeah.
I-I always feel like I'm the most excited out of everybody.
Really? -Yeah.
Because excited when nothing's happening. Cleaning some dust off a piece of glass
and it still seems exciting, because I think this is the key piece of glass in our
system and I'm just clean dust off of it. How cool is that?
On January 4th,
just like a few hours after midnight. Boom. We got another signal much like the
first signal we found in September of 2015. And it's also well represented by
these black holes that we're sitting on. One of the black holes had a mass of
about 30 solar masses and the other one was about 20. And this one lasted
longer than the first one. Both because our detectors are better at the lowest
frequencies and because the signal is from black holes which are smaller, so
they last longer. And it's really dramatic if you listen to the audio.
The first signal that we got, it's only audible for about a tenth of a second.
It's just, "boomp," like this. But this new one sounds like "bvoom."
It's a little bit more drawn-out and it comes from farther away.
It's the furthest black hole merger that we've been able to detect. So it's about three billion light
years away, which means that signal-- the merger actually happened three billion
years ago and the signal has been propagating to us for three billion years.
What's particularly interesting in this merger are hints that the two black
holes weren't spinning with the same orientation as each other or as their orbit.
This suggests that rather than forming out of binary stars, they formed
separately and later became entwined through orbital dynamics.
This one really says, okay, we now know that we're going
to be seeing a lot of these things.
It's a...
It's a relief to have another signal to know that the universe is not just populated
by all tiny, tiny black holes or by no black holes.
If we improve our detector
sensitivity by say a factor of two or three, the rates will go up from, you know,
seeing one every month or every two months to seeing one every day or every week.
I would say it's very surprising now that our first three signals came
from binary black hole mergers which, were pretty much an unexpected source
as of mid-2015.
There's a working theory -- kind of exotic -- that says that some of
the black holes we're seeing are primordial, alright? They weren't formed
through, you know, conventional supernova explosions. They were formed during the
Big Bang themselves. And they could be a part of Dark Matter, component of dark matter.
So we may actually determine after we get statistics on
lots and lots and lots of these black hole mergers that we're actually seeing
maybe a hint of dark matter.
It's sort of scratching at the door of the biggest
mysteries that we have today in cosmology.
In the past before there were any signals, people used to use this phrase,
which I completely disagree with.
And they would say, "you know if we don't find any signals it will be even more
interesting than if we do." I said no no no no no. No no no no.
Lots of signals. That's what we want.
But now that we have a few, I'm feeling a little bit more
complacent. And so I'd say we really expected to see a lot of binary neutron stars,
and if we don't, well isn't that interesting? It means there's something going on--
You know, you have all the pieces. We already know how neutron stars work.
We've seen neutron stars using radio astronomy. We know they're
out there, we know that they come together in binaries.
But why don't we see their gravitational waves?
So it could be something else happens to them
just before the final merger and there's something in their evolutionary track
which goes off in a different direction than what we expect.
And I think that would actually be interesting. I guess I've become one of those people that
said if you don't see it then maybe it's interesting, because we'll learn something.
You never know how many more signals we have sitting in the can that we're not
telling you about.
Can you say that again?
I don't think so. -Would you give me the exclusive, Rana?
I would! You know it, Derek. Come on. If I had secret signals, you'd be the first to know.
These lights are the first two tentacles of the jellyfish I'm
building, and there's a neural network which then drives this little chip, which
modulates these lights. And it's going to use these sensors like the proximity and the
sound to figure out if people are close to it. And the neural network is going to
train itself to flash the tentacle lights to make people come closer to it.


NEW Gravitational Wave Discovery!

46 分類 收藏
林宜悉 發佈於 2020 年 3 月 29 日
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