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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.

I've come to Caltech because there is a brand new gravitational wave discovery.


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B1 中級

NEW 重力波発見! (NEW Gravitational Wave Discovery!)

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    林宜悉 に公開 2021 年 01 月 14 日