Europa's Ocean Secrets, Gravitational Waves & Black Hole Mysteries

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Andrew Dunkley: Hi, Andrew Dunkley here. Fred and I are

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taking a little bit of a break over the

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Christmas New Year period just to catch our

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breath. We'll be back, uh, sometime around

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mid January. In the meantime, we've been

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digging through the archives at some of the

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most perplexing and popular

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episodes that we've done in recent times. So

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sit back and enjoy. 15

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seconds. Guidance is internal.

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Professor Fred Watson: 10, 9. Ignition

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sequence start. Space nets.

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Andrew Dunkley: 5, 4, 3.

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Professor Fred Watson: 2. 1, 2, 3, 4, 5, 5, 4, 3,

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2, 1.

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Andrew Dunkley: Space nuts astronauts report it feels

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good. Hi there and thanks for joining us on

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the Space Nuts podcast. My name's Andrew

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Dunkley, your host. And joining me, uh, as

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always, Professor Fred Watson, Astronomer at

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Large from the department of Da da da da da

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da da. It's a pretty long title. That's what

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we'll call it from now on. G', day, Fred.

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Professor Fred Watson: You could call me the Aaliyah.

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Andrew Dunkley: Aal.

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Professor Fred Watson: Yeah, when I was Astronomer in Charge, I was

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aic. Um, the only trouble is

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AAL actually has another significant

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meaning in Australian astronomy because it

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doesn't only stand for Astronomer at Large,

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it also stands for Astronomy Australia

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Limited. So, uh, just throw that idea out.

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That's a rubbish idea. I'll just be

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astronomer.

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Andrew Dunkley: Yeah, I was once given the title urrs.

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But anyway, um,

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some people will understand that.

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Professor Fred Watson: Yeah, you've got lovely friends, haven't you?

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Andrew Dunkley: I've got a lot of good friends, yes.

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Now today we're going to talk about some very

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exciting things. It looks like black holes

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are still in people's minds. So we're going

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to be talking about, um, a couple of

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questions that have come in from people about

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infinite density. Uh, density. I

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keep getting it mixed up with destiny. I

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don't know why. Might have been a Back to the

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Future movie that confused me on that front.

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Uh, uh, and issues, uh, photographing a black

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hole. Why were they issues at all? And uh,

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another question about space travel and uh,

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near light speed travel. Uh, we're also

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going to, uh, look at,

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um, the cause of a gravitational

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wave that was detected recently. This is

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exciting because they think they've

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pinpointed, uh, an actual cause.

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And we're going to start off today.

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Professor Fred Watson: Fred, by talking about, uh, this rather.

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Andrew Dunkley: Exciting mission that's one step closer to

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happening. A mission to Jupiter's ice

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moon Europa. And that's what we'll start

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with. This, uh, well, this afternoon, this

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morning, tonight, this evening, yesterday.

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Professor Fred Watson: Whenever. Whenever it is. Yeah, it's,

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yeah. So look, a terrific story. Very good

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news from uh, NASA that they,

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um, the powers that be within NASA have uh,

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given the go ahead um, for a

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mission called Europa Clipper, which is, is

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one of the uh, missions that's been

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uh, postulated or sorry proposed is a better

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word for um, exploring the moons of the outer

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planets. There are a number that are kind of

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on the, on the table at the moment, some

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further advanced than others. But Europa

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Clipper is pretty well advanced and

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as you can tell its target, its main target

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is Jupiter's moon Europa, which is one of

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these um, ocean moons. Ice, uh,

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ocean moons. Uh, we believe it has

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a covering of ice and we don't know whether

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it's thin ice or thick ice. So that would be

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one of the things that Europa Clipper would

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find out. Um, and an ocean underneath it

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and a rocky core. Uh, so

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Europa Clipper, I think they are

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talking about having it ready for launch in

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2023 which is

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um, you know, fantastic if they can

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do that. That's right. Uh, but apparently

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um, that's the

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baseline commitment as it's called, supports

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a launch readiness date by 2025.

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Um, it's all being done at ah, the Propulsion

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Laboratory in Pasadena. That's where the

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spacecraft will be built. So they've got the

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go ahead, um, it's

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got the next step,

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uh, in approval from NASA, which

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I think is a pretty solid one. So I

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think you and I, back in 2025

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we'll be talking a lot about Europa Clipper.

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Andrew Dunkley: Maybe what will be the

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basis of the mission? Are they just going

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there to have a look?

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Professor Fred Watson: Because it is a bit like uh, but it's

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a very good look. Um, so it's not going to

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land on Europa. It is a proposal to go into

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orbit around Europe, actually to go into

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orbit around Jupiter. Uh and of course

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orbiting Jupiter is always hazardous because

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of um, the

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intense uh, radiation belts that Jupiter

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has. It's got a magnetic field thousands of

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times bigger than the Earth and has these

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high energy radiation belts around it that

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threaten to melt the innards of spacecraft.

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Uh, so like the uh, Juno mission which

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is currently in orbit around Jupiter, this

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uh, Europa Clipper will go into a very

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elongated uh, orbit, um, which

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will uh, give it 45

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flybys of Europa. Uh and

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their altitudes will vary from

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2700km to 25km.

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So it will really be skimming over the

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surface. Oh well, and it's got this huge

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science package with all the kind of,

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you know, the gubbins that you would expect

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to find on board something like that,

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a mass spectrometer, uh, which

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basically measures, you know the weights

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of atoms, as you might guess. Uh,

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it, um, that is interesting because

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Europa, like Saturn's moon Enceladus,

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is thought to have, although it hasn't really

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been properly confirmed, but thought to have

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ice, uh, fountains coming out of

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it, um, which are water that's

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squirting up through its, uh, through its icy

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shell and instantly freezing. It's not

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frozen. But if you fly through it, as

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Cassini did with Enceladus, then you can

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sample what the atomic makeup is. And so

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the mass spectrometer will help with that.

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Uh, and also, um, it's got this ground

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penetrating radar and that's going to be

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crucial in characterizing

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Europa's crust, um, and

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revealing how much of, you know, the

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potential water within is oceanic, as

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is expected, uh, or whether it is just

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pockets of water as we find in Antarctica

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and indeed around the South Pole of Mars.

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Andrew Dunkley: Will they be able to tell what kind of water

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it is?

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Professor Fred Watson: Um, uh, to some

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extent they will. Um, it may

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require a bit of, you know,

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inference from other measurements, but if

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you've got, uh, samples of ice crystals,

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uh, then you can do exactly that. You can,

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you know, you can uh, basically

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tell whether it's saline water or fresh water

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because you can see the, you can measure the

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salt content of it.

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Andrew Dunkley: It.

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Professor Fred Watson: So like um, Saturn's moon

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Enceladus, uh, which is actually quite

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rich in minerals and it's the silicates in

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that that tells you that this water was once

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in contact with rock. Uh, I think

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the Europa Clipper will be able to sample

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exactly those things too. Assuming these

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plumes are real, because they're not

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well observed. There is evidence. I've seen

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images that seem to show these plumes

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coming from Europa. Uh, assuming they're real

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when they fly through, um, hopefully we will

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be able to tell what kind of water it is.

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Exactly.

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Andrew Dunkley: And will they be able to tell how much

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water there is underneath the surface?

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Professor Fred Watson: Yes they will because that will very

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much be revealed by the um, the ground

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penetrating radar in exactly the way

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that, um, um, one of the spacecraft in orbit

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around Mars, I think it was the, I think it

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was, might even have been Mars Reconnaissance

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Orbiter, I'm not sure, detected this

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lake of liquid water underneath the ice cap

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of the southern ice cap of Mars about a year

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ago you and I spoke about it. Um, and

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they can tell exactly how much there is there

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because you can see the boundary with this

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sort of radar. You can see the boundary

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between an ice surface and a water surface.

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And that's crucial to doing this so.

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Andrew Dunkley: This mission won't actually be looking

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for life, but it will be looking

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for, uh, the potential for life

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to perhaps exist on a moon

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like this.

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Professor Fred Watson: Exactly. So as the blurb,

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um, on the NASA website says, uh, it

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will help scientists investigate the chemical

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makeup of Europa's potentially habitable

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environment while minimizing the need to

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drill through layers of ice so that what

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they're going to try and do is as much as

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they can from orbit. Um, and

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then if there's like, if they find

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lipids and amino acids and all this sort of

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thing, uh, in the plumes of ice coming,

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coming from Europa, then clearly the next

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step will be a lander, uh, that starts

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digging holes in the ice.

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Andrew Dunkley: Yes.

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Professor Fred Watson: I mean, you know, before you do that, the

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first thing you need to know is how thick the

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ice is. Yes.

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Andrew Dunkley: If it's a couple of miles thick.

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Professor Fred Watson: Well, actually, a couple of miles

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is better than what they're expecting.

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Andrew Dunkley: Oh, is that right?

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Professor Fred Watson: More like 25 or 30 miles

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or kilometers. M. That's right. Choose your

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units. Um, yes. So, yes,

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a thinner layer of ice will be

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pretty, pretty, um, good to, you know, to

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cope with. You could probably do that. I mean

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by thin, I mean less than a kilometer,

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probably. Yes.

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Andrew Dunkley: But the likelihood, uh, is it's, it's

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probably more, but I guess we'll, we'll have

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to wait and see.

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Professor Fred Watson: Um, Europa's covered in all these cracks that

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are, that are brownish in color.

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Andrew Dunkley: Yes.

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Professor Fred Watson: That's thought to be the effect of sunlight

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on brine, on basically on salt water. So

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you've already got a hint there that, uh,

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it's probably a salty ocean underneath the

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surface.

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Andrew Dunkley: Well, salt's probably not that uncommon in

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the universe really.

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Professor Fred Watson: Um, that's right. It's not.

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Andrew Dunkley: It's one of, one of the base materials, isn't

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it? Uh, of course, this doesn't guarantee

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they're actually going to go. This is just

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another step forward in the approval process.

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Professor Fred Watson: It does, it does.

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Andrew Dunkley: Very longitudinal process and they have to

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get over a lot of hurdles before they

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actually hit the launch button. So, uh,

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hopefully they're, um, they're going to get

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there and um, it's. It's a long trip too.

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Professor Fred Watson: Yes, it is. That's the other thing.

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Andrew Dunkley: So they've got to time it right. They've got

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to get in the right place at the right time.

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Professor Fred Watson: Exactly. All of the above. That's right. So,

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uh, at least what it, you know, at least, uh,

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it's not a knockback. That's the good news.

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Andrew Dunkley: Indeed. All right, well, we'll keep an eye on

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this story because I'm sure there'll be more

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to report in the not too distant future about

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uh, a mission to Europa. You're listening

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00:10:48.440 --> 00:10:51.080
to Space Nuts with Andrew Dunkley and Fred

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00:10:51.080 --> 00:10:51.720
Watson.

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Professor Fred Watson: Space Nuts.

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Andrew Dunkley: Now Fred, we've uh, discussed

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00:12:51.860 --> 00:12:54.410
uh, gravitational waves before and

315
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uh, a few of those have been detected in

316
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recent times. The problem with them

317
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is what is the cause?

318
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And now in a recently detected

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gravitational wave they think they've got a

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candidate.

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Professor Fred Watson: That's, that's right. This is so this is, you

322
00:13:11.610 --> 00:13:14.460
know, it's a, an ongoing story. Uh,

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what I like about this story is it's got a

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nice Australian component because there is

325
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um, there's a, basically

326
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a collaboration here in Australia which is

327
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called osgrav, uh, which is about

328
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gravitational waves. It's a kind of fairly

329
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predictable name but um, it includes people

330
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from the Australian National University and

331
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I think University of Western Australia Other

332
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places which are strong in gravitational wave

333
00:13:38.910 --> 00:13:41.790
astronomy. So, um, it's very nice

334
00:13:41.790 --> 00:13:43.830
that it's. It has this Australian component.

335
00:13:43.830 --> 00:13:46.550
So what's the story? Well, uh, the large.

336
00:13:47.110 --> 00:13:49.070
Sorry, uh, the Laser Interferometer

337
00:13:49.070 --> 00:13:51.790
Gravitational Wave Observatory, Otherwise

338
00:13:51.790 --> 00:13:54.790
known as LIGO, um, has been operating

339
00:13:55.110 --> 00:13:57.910
since, uh, 2015 in its

340
00:13:58.390 --> 00:14:00.350
sort of current state. It's actually

341
00:14:00.350 --> 00:14:02.750
technically called Advanced LIGO because I

342
00:14:02.750 --> 00:14:05.470
think it took 15 years of development to get

343
00:14:05.470 --> 00:14:08.070
to this stage. But they have,

344
00:14:08.600 --> 00:14:11.420
uh, now, not quite regularly, but at, uh,

345
00:14:11.420 --> 00:14:13.790
fairly infrequent intervals. Sorry,

346
00:14:13.790 --> 00:14:16.670
fairly moderately moderate intervals.

347
00:14:16.670 --> 00:14:18.310
Let me put it that way. They've been

348
00:14:18.310 --> 00:14:21.070
detecting gravitational wave events. And for

349
00:14:21.070 --> 00:14:22.710
the last couple of years they've had an

350
00:14:22.710 --> 00:14:24.230
additional string to their bow. Remember,

351
00:14:24.230 --> 00:14:26.190
there are two of these detectors at opposite

352
00:14:26.190 --> 00:14:28.350
corners of the United States,

353
00:14:28.940 --> 00:14:31.470
um, which, um, you need because,

354
00:14:31.960 --> 00:14:34.270
uh, otherwise you've got no idea where these

355
00:14:34.270 --> 00:14:36.230
things come from or even if they're real. You

356
00:14:36.230 --> 00:14:38.870
need to see the gravitational wave pass one

357
00:14:38.870 --> 00:14:40.650
and then the other with the right kind of

358
00:14:40.650 --> 00:14:43.210
time interval in between. Um, but they've

359
00:14:43.210 --> 00:14:44.970
been joined in the last few years by

360
00:14:44.970 --> 00:14:47.770
something called, uh, uh, Virgo, which,

361
00:14:47.980 --> 00:14:49.650
uh. In fact, I think it's called Advanced

362
00:14:49.650 --> 00:14:51.730
Virgo. Like Advanced ligo. Virgo is an

363
00:14:51.730 --> 00:14:54.610
Italian gravitational wave detector. And of

364
00:14:54.610 --> 00:14:57.130
course, having three detectors widely spread

365
00:14:57.370 --> 00:14:59.010
over the surface of the Earth, uh, means you

366
00:14:59.010 --> 00:15:01.570
can pinpoint things much more accurately in

367
00:15:01.570 --> 00:15:03.050
terms of the direction in which these

368
00:15:03.050 --> 00:15:04.570
gravitational waves come in.

369
00:15:04.570 --> 00:15:06.570
Andrew Dunkley: From triangulating the signal.

370
00:15:07.200 --> 00:15:09.280
Professor Fred Watson: Exactly. That's exactly what it is.

371
00:15:09.650 --> 00:15:12.320
Um, what's interesting about this one though,

372
00:15:12.400 --> 00:15:15.280
is that the signal seems to be

373
00:15:15.680 --> 00:15:18.680
from a black hole absorbing

374
00:15:18.680 --> 00:15:19.680
a neutron star.

375
00:15:21.450 --> 00:15:24.240
Um, we actually had a false alarm on

376
00:15:24.240 --> 00:15:27.240
this, which is embarrassing because, um, my

377
00:15:27.240 --> 00:15:29.200
book has just gone to the printer saying,

378
00:15:29.200 --> 00:15:31.400
yes, we've observed a neutron star being

379
00:15:31.400 --> 00:15:34.060
absorbed by a black hole. Um, and

380
00:15:34.860 --> 00:15:36.780
that I think disappeared because it turned

381
00:15:36.780 --> 00:15:39.660
out to be, um, terrestrial noise. It was

382
00:15:39.740 --> 00:15:41.420
sort of, you know. So I don't know whether it

383
00:15:41.420 --> 00:15:44.380
was a train going underneath oven probably,

384
00:15:44.380 --> 00:15:46.140
or. Yeah, something like that. That's the

385
00:15:46.140 --> 00:15:48.780
usual story, isn't it? A microwave oven. Um,

386
00:15:48.780 --> 00:15:51.420
that was earlier this year. And that,

387
00:15:51.540 --> 00:15:54.300
um, has now gone away. But it looks as

388
00:15:54.300 --> 00:15:57.300
though this one might actually be the

389
00:15:57.300 --> 00:15:59.740
real thing. A black hole and a neutron star.

390
00:16:00.220 --> 00:16:02.860
We've had two black holes merging. Uh,

391
00:16:03.930 --> 00:16:06.170
that's probably been the commonest source of,

392
00:16:06.200 --> 00:16:07.730
uh, gravitational waves. There've been

393
00:16:07.730 --> 00:16:09.570
several of those. We've had a couple of

394
00:16:09.570 --> 00:16:12.090
neutron stars merging as well. And that

395
00:16:12.090 --> 00:16:14.570
actually comes with celestial fireworks that

396
00:16:14.650 --> 00:16:17.490
you can observe with other types of

397
00:16:17.490 --> 00:16:19.850
telescope like neutrino telescopes, visible

398
00:16:19.850 --> 00:16:22.250
light telescopes, radio Telescopes, X ray

399
00:16:22.250 --> 00:16:25.050
telescopes, all of the above. Um, and

400
00:16:25.050 --> 00:16:27.730
that was a big story actually late last year

401
00:16:27.730 --> 00:16:30.570
if I remember rightly. But, um, until

402
00:16:30.570 --> 00:16:32.250
now we haven't had a confirmed,

403
00:16:33.670 --> 00:16:36.250
um, observation of a neutron star

404
00:16:36.490 --> 00:16:38.290
being absorbed by a black hole. And we still

405
00:16:38.290 --> 00:16:41.050
don't have. It's still a bit speculative,

406
00:16:41.370 --> 00:16:44.210
but from the masses that are inferred by the

407
00:16:44.210 --> 00:16:45.930
signal. And remember what you get is this

408
00:16:45.930 --> 00:16:48.430
weird gravitational chirp, uh,

409
00:16:48.430 --> 00:16:51.370
it's uh, the frequency of a sound wave

410
00:16:51.370 --> 00:16:54.330
going as the two things come

411
00:16:54.330 --> 00:16:56.850
together. Um, and it's that. That gives you

412
00:16:56.850 --> 00:16:58.920
all the details of what it is that that are

413
00:16:58.920 --> 00:17:01.480
colliding. The suspicion is it's two

414
00:17:01.480 --> 00:17:04.080
objects, one of which is three solar

415
00:17:04.080 --> 00:17:06.880
masses and the other is five

416
00:17:07.200 --> 00:17:10.000
solar masses. I think I'm right in saying

417
00:17:10.000 --> 00:17:12.560
that I should uh, check those numbers. But

418
00:17:12.560 --> 00:17:15.440
anyway, uh, that is the current

419
00:17:16.080 --> 00:17:18.960
expectation, uh, of what is colliding. So

420
00:17:19.040 --> 00:17:21.880
something three solar masses would have to

421
00:17:21.880 --> 00:17:24.000
be a neutron star because it's two

422
00:17:24.959 --> 00:17:27.519
lightweight uh, to be a black hole.

423
00:17:27.599 --> 00:17:30.239
And so, uh, that is what's making this

424
00:17:30.239 --> 00:17:32.799
interesting. What's

425
00:17:32.799 --> 00:17:35.359
perhaps, um, a bit surprising,

426
00:17:35.990 --> 00:17:38.319
uh, is that

427
00:17:38.719 --> 00:17:40.879
you might expect there to be once again

428
00:17:41.279 --> 00:17:43.639
radiation, uh, coming from this, not just

429
00:17:43.639 --> 00:17:46.639
gravitational radiation, but uh, noise

430
00:17:46.639 --> 00:17:49.050
in the X ray spectrum or uh,

431
00:17:49.050 --> 00:17:51.999
neutrinos, uh, particles, things of that

432
00:17:51.999 --> 00:17:54.650
sort, but it hasn't been

433
00:17:54.810 --> 00:17:57.250
observed. And um,

434
00:17:57.610 --> 00:17:59.930
one of the Australian astronomers, uh,

435
00:18:00.610 --> 00:18:02.170
uh, I've forgotten her first name. That's

436
00:18:02.170 --> 00:18:04.730
embarrassing, isn't it? Susan. Susan Scott.

437
00:18:04.910 --> 00:18:07.690
Uh, she's at um, anu Australian

438
00:18:07.690 --> 00:18:10.250
National University. Uh, she says that

439
00:18:10.650 --> 00:18:13.610
uh, if she said. Well

440
00:18:13.610 --> 00:18:15.090
what she says is we've looked for light

441
00:18:15.090 --> 00:18:16.930
signatures of the event, but no one has found

442
00:18:16.930 --> 00:18:19.490
any up to this point. That indicates that if

443
00:18:19.490 --> 00:18:22.290
it is a black hole and a neutron star, then

444
00:18:22.290 --> 00:18:24.690
very likely the neutron star has been

445
00:18:24.690 --> 00:18:27.370
swallowed whole by, by the black hole. Uh,

446
00:18:27.450 --> 00:18:29.750
uh, he said, and she says this could happen

447
00:18:29.750 --> 00:18:32.310
if the objects were of different masses.

448
00:18:32.870 --> 00:18:35.550
So it's. The smaller object gets sucked in

449
00:18:35.550 --> 00:18:37.590
more quickly and, and is swallowed whole. So

450
00:18:37.590 --> 00:18:40.390
you know, it's not strung out into, into this

451
00:18:41.410 --> 00:18:44.230
um, mess of material that does emit

452
00:18:44.490 --> 00:18:46.590
um, uh, signals in the

453
00:18:46.590 --> 00:18:49.100
electromagnetic uh, wave bands. Uh,

454
00:18:49.270 --> 00:18:52.070
if it gets sucked in hole, maybe you don't

455
00:18:52.070 --> 00:18:53.870
get any signal at all except for the

456
00:18:53.870 --> 00:18:55.070
gravitational wave signal.

457
00:18:55.070 --> 00:18:56.870
Andrew Dunkley: It's extraordinary how sudd

458
00:18:58.210 --> 00:19:01.050
impact be. I mean, you know, neutron

459
00:19:01.050 --> 00:19:03.330
stars, we've talked about them and they're

460
00:19:03.330 --> 00:19:05.890
pretty volatile individuals and

461
00:19:06.130 --> 00:19:08.590
quite dense, um,

462
00:19:08.850 --> 00:19:09.570
quite dense.

463
00:19:09.730 --> 00:19:11.890
Professor Fred Watson: It's just a slight understatement there.

464
00:19:12.770 --> 00:19:13.570
Yes, indeed.

465
00:19:13.930 --> 00:19:16.850
Andrew Dunkley: Um, so I imagine

466
00:19:16.850 --> 00:19:19.010
it'd be quite a cataclysmic collision.

467
00:19:19.170 --> 00:19:22.130
Professor Fred Watson: Yeah, that's right. Um, in fact, so

468
00:19:22.130 --> 00:19:25.090
when you've got two black holes, um, what you

469
00:19:25.090 --> 00:19:27.010
get at the end of it is a more massive black

470
00:19:27.010 --> 00:19:30.010
hole. Uh, and, um, you're

471
00:19:30.010 --> 00:19:32.850
talking there though about, you

472
00:19:32.850 --> 00:19:35.330
know, infinitely small, infinitesimally small

473
00:19:35.330 --> 00:19:38.330
points merging, uh, their event horizon.

474
00:19:38.890 --> 00:19:41.210
There are two event horizons merge as well,

475
00:19:41.210 --> 00:19:42.890
and you get something called the ring down

476
00:19:42.890 --> 00:19:45.130
where the event horizon itself vibrates.

477
00:19:45.810 --> 00:19:48.690
Um, I think with a neutron star you wouldn't

478
00:19:48.690 --> 00:19:51.020
have the event horizon, but it will be

479
00:19:51.020 --> 00:19:53.380
possible for the neutron star just basically

480
00:19:53.380 --> 00:19:55.100
to disappear. Over the black holes event

481
00:19:55.100 --> 00:19:57.210
horizon, you don't see anything. But, uh,

482
00:19:57.340 --> 00:19:59.260
neutron stars themselves, as you and I have

483
00:19:59.260 --> 00:20:01.020
talked about many times, are active in the

484
00:20:01.020 --> 00:20:02.900
sense that they've got highly intense

485
00:20:02.900 --> 00:20:05.580
magnetic fields on their surfaces and they

486
00:20:05.580 --> 00:20:07.940
beam this radiation out, which we see as

487
00:20:08.260 --> 00:20:11.060
pulsars. So they're not particularly

488
00:20:11.060 --> 00:20:13.700
quiet things. I mean, this thing could be a

489
00:20:13.700 --> 00:20:16.220
pulsar whose lighthouse beam of

490
00:20:16.220 --> 00:20:19.180
radiation is missing the Earth, if I can put

491
00:20:19.180 --> 00:20:21.300
it that way. Because the only reason we see

492
00:20:21.300 --> 00:20:23.380
pulsars is when you've got a neutron star

493
00:20:23.780 --> 00:20:26.540
whose, uh, beams of radiation from their

494
00:20:26.540 --> 00:20:28.780
poles actually sweeps across the Earth. And

495
00:20:28.780 --> 00:20:30.810
that of course, is a particular, uh,

496
00:20:30.820 --> 00:20:33.780
circumstance. Maybe this one wasn't like

497
00:20:33.780 --> 00:20:36.340
that and it's just got chewed up, uh, and

498
00:20:37.220 --> 00:20:40.140
we haven't seen its demise other than in

499
00:20:40.140 --> 00:20:41.380
the gravitational waves.

500
00:20:41.380 --> 00:20:43.140
I think there'll be more about this story,

501
00:20:43.220 --> 00:20:45.460
Andrew, and, um, I hope you and I can bring

502
00:20:45.460 --> 00:20:48.140
it to our, uh, Space Nuts

503
00:20:48.140 --> 00:20:50.950
listeners or listeners, our fraternity.

504
00:20:52.390 --> 00:20:54.810
Andrew Dunkley: Yes, uh, well, um,

505
00:20:55.590 --> 00:20:58.310
the more we can gather in terms of data,

506
00:20:58.550 --> 00:21:01.230
uh, on gravitational waves, the more we

507
00:21:01.230 --> 00:21:04.190
will learn and who knows what

508
00:21:04.190 --> 00:21:05.790
sort of problems it could solve down the

509
00:21:05.790 --> 00:21:06.470
track, so.

510
00:21:06.950 --> 00:21:09.310
Professor Fred Watson: Exactly. It's always my comment that you

511
00:21:09.310 --> 00:21:12.110
never know what you're setting in store for

512
00:21:12.110 --> 00:21:13.670
the future from all this knowledge.

513
00:21:13.830 --> 00:21:14.430
Andrew Dunkley: Exactly.

514
00:21:14.430 --> 00:21:14.790
Professor Fred Watson: Yeah.

515
00:21:14.790 --> 00:21:16.450
Andrew Dunkley: I, uh, mean, you just, just gather the

516
00:21:16.450 --> 00:21:18.430
knowledge. One day it might just go, you, ah,

517
00:21:18.570 --> 00:21:20.250
know, a penny will drop with someone else,

518
00:21:20.250 --> 00:21:23.050
maybe a generation down the track, who knows?

519
00:21:23.370 --> 00:21:25.970
It's all useful. And even if it's not, it's

520
00:21:25.970 --> 00:21:28.930
good to be able to gather it and they

521
00:21:28.930 --> 00:21:29.850
use it. Some, some.

522
00:21:29.850 --> 00:21:32.730
Professor Fred Watson: That's right. It's um, you know, all these

523
00:21:32.730 --> 00:21:34.770
things are constantly testing Einstein's

524
00:21:34.770 --> 00:21:36.890
theory of relativity. And that's

525
00:21:38.010 --> 00:21:39.730
very, um, important because we know there's

526
00:21:39.730 --> 00:21:41.050
something wrong with it, but we haven't found

527
00:21:41.050 --> 00:21:43.050
anything wrong with it yet. Even though it's

528
00:21:43.050 --> 00:21:45.250
been tested within an inch of its life, it's

529
00:21:45.250 --> 00:21:46.620
still holds up.

530
00:21:46.940 --> 00:21:48.140
Andrew Dunkley: Yeah, fascinating.

531
00:21:48.140 --> 00:21:51.100
All right, you're listening to the Space Nuts

532
00:21:51.100 --> 00:21:54.060
podcast With Andrew Dunkley and Fred Watson.

533
00:21:56.380 --> 00:21:58.860
Professor Fred Watson: Okay, we checked all four systems and being

534
00:21:58.860 --> 00:22:00.300
with a girl, Space Nuts.

535
00:22:00.300 --> 00:22:02.500
Andrew Dunkley: Now Fred, I do want to shout out once again

536
00:22:02.500 --> 00:22:05.380
to our patrons, um, that number

537
00:22:05.380 --> 00:22:08.260
39 now thank uh, you so

538
00:22:08.260 --> 00:22:10.420
much for supporting the Space Nuts podcast.

539
00:22:10.420 --> 00:22:13.020
We so appreciate it. And if you're interested

540
00:22:13.020 --> 00:22:14.920
in becoming a patron, you can, can do

541
00:22:14.920 --> 00:22:17.920
so@patreon.com spacenuts

542
00:22:17.920 --> 00:22:19.400
that's patreon.com

543
00:22:20.520 --> 00:22:23.240
spacenuts and um, thank you to

544
00:22:23.240 --> 00:22:25.720
everybody who has joined the Space Nuts

545
00:22:25.720 --> 00:22:28.400
podcast group. They number in their hundreds.

546
00:22:28.400 --> 00:22:31.360
Now Fred, we've only had the page going for

547
00:22:31.360 --> 00:22:33.920
a bit over a week and uh, already we've

548
00:22:33.920 --> 00:22:35.880
tracked the century and

549
00:22:36.760 --> 00:22:39.400
have over 100 people that are all Space Nuts

550
00:22:39.400 --> 00:22:41.440
fans who are all now talking to each other

551
00:22:41.440 --> 00:22:43.580
and uh, answering each other's questions and,

552
00:22:43.730 --> 00:22:46.690
and uh, having a fair bit of fun. So I'm

553
00:22:46.690 --> 00:22:49.410
so pleased we were able to put um, those

554
00:22:49.410 --> 00:22:51.410
people together and who uh, knows friends,

555
00:22:51.570 --> 00:22:54.530
friendships may be forged. Uh, that's

556
00:22:54.530 --> 00:22:56.610
great. Or collaborations that might solve

557
00:22:56.610 --> 00:22:58.210
some of the mysteries of the universe. Who

558
00:22:58.210 --> 00:23:01.010
knows, uh, that would be a lovely legacy I

559
00:23:01.010 --> 00:23:03.970
think. Uh, let's um, and of course if

560
00:23:03.970 --> 00:23:06.410
you would like to be a member uh, of the

561
00:23:06.410 --> 00:23:09.110
Space Nuts podcast group, um, just find it,

562
00:23:09.180 --> 00:23:11.780
it, it's on Facebook, uh, Space Nuts podcast

563
00:23:11.780 --> 00:23:14.380
group in your search engine and um, yes, just

564
00:23:14.380 --> 00:23:17.060
ask to join and we will click the approve

565
00:23:17.060 --> 00:23:19.780
button. Everybody seems to be like minded and

566
00:23:19.780 --> 00:23:21.660
enjoying themselves. So uh, that's what it's

567
00:23:21.660 --> 00:23:22.060
all about.

568
00:23:23.500 --> 00:23:26.460
Now Fred, some questions if you

569
00:23:26.460 --> 00:23:29.380
will. Um, hello again fellow nutters.

570
00:23:29.380 --> 00:23:31.340
I have a question I'm hoping you can help me.

571
00:23:31.500 --> 00:23:33.860
Um, understanding an old

572
00:23:33.860 --> 00:23:36.780
chestnut black holes. If a black hole is

573
00:23:36.780 --> 00:23:39.380
an infinite dense point, why does it have a

574
00:23:39.380 --> 00:23:42.240
diameter? I don't why astronomers refer

575
00:23:42.240 --> 00:23:44.400
to black holes by their size in terms of

576
00:23:44.400 --> 00:23:46.240
diameter. When it's meant to be a point of

577
00:23:46.240 --> 00:23:48.960
infinite density, are they

578
00:23:48.960 --> 00:23:51.560
mistakenly referring to the event horizon?

579
00:23:51.560 --> 00:23:54.440
Mario from Melbourne. Hello Mario. Thanks for

580
00:23:54.440 --> 00:23:54.840
the question.

581
00:23:55.720 --> 00:23:57.880
Professor Fred Watson: And the answer is yes, thank you Mario.

582
00:23:57.880 --> 00:23:58.760
Andrew Dunkley: Thanks for the question.

583
00:23:59.420 --> 00:24:02.320
Professor Fred Watson: Um, Mario then goes on to uh, you

584
00:24:02.320 --> 00:24:05.000
know, everything he says is absolutely right,

585
00:24:05.000 --> 00:24:07.850
that um, uh, if you've got a, a

586
00:24:07.850 --> 00:24:10.170
point of infinite density, it's got zero

587
00:24:10.250 --> 00:24:12.970
dimensions, so you can't refer to its

588
00:24:12.970 --> 00:24:15.890
diameter. Uh, what you can refer to is

589
00:24:15.890 --> 00:24:18.560
its mass because the mass is uh,

590
00:24:19.050 --> 00:24:21.970
variable. Uh, but the fact that

591
00:24:21.970 --> 00:24:24.930
it has no volume means that when you, you

592
00:24:24.930 --> 00:24:26.450
know, when you look at the mass per unit

593
00:24:26.450 --> 00:24:27.970
volume, you've got something of infinite

594
00:24:27.970 --> 00:24:30.330
density, which is how density is defined.

595
00:24:30.650 --> 00:24:33.530
So Mario is absolutely right. Uh, what

596
00:24:33.530 --> 00:24:36.170
does vary though? With the maps is the event

597
00:24:36.170 --> 00:24:38.290
horizon, the diameter of the event horizon,

598
00:24:38.290 --> 00:24:40.920
which you and I have spoken before. Um,

599
00:24:41.360 --> 00:24:44.150
uh, uh, it's a

600
00:24:44.150 --> 00:24:47.110
quantity that I suppose is

601
00:24:47.190 --> 00:24:49.990
important because if we are observing,

602
00:24:50.380 --> 00:24:52.910
um, a black hole, as we did with the Event

603
00:24:52.910 --> 00:24:54.790
Horizon telescope, then that's what you see.

604
00:24:55.300 --> 00:24:56.870
Uh, so a big one is going to be easier to

605
00:24:56.870 --> 00:24:58.630
observe than a smaller one. And that's why a

606
00:24:58.630 --> 00:25:00.950
supermassive black hole, uh, in the center of

607
00:25:00.950 --> 00:25:03.590
a galaxy called M M87 was chosen for the

608
00:25:03.590 --> 00:25:05.630
first target for that Event Horizon

609
00:25:05.630 --> 00:25:07.750
Telescope. But no, Mario, you're quite right.

610
00:25:07.910 --> 00:25:10.750
Um, it is that, uh, astronomers, when,

611
00:25:10.750 --> 00:25:12.350
if they talk about the diameter of a black

612
00:25:12.350 --> 00:25:14.510
hole, and that probably includes me as well,

613
00:25:14.890 --> 00:25:16.870
uh, are actually really referring to the

614
00:25:16.870 --> 00:25:19.390
event horizon because that's the parameter.

615
00:25:19.470 --> 00:25:22.350
And I love the way Mario signs off by saying

616
00:25:22.350 --> 00:25:25.130
thanks in advance to Dave and Fred. Uh,

617
00:25:25.130 --> 00:25:27.470
although he does say, AKA Andrew.

618
00:25:27.950 --> 00:25:29.790
Andrew Dunkley: Yes, that one's going to stick for a while,

619
00:25:30.750 --> 00:25:33.630
sorry to say. Thank you, Mario.

620
00:25:35.190 --> 00:25:37.550
Moving on. Uh, hi, Andrew and Fred. It's

621
00:25:37.550 --> 00:25:39.590
Andrew from Newcastle with another question,

622
00:25:39.670 --> 00:25:42.430
if I may. Just watched a doco on the quest

623
00:25:42.430 --> 00:25:44.430
to capture the first photograph of a black

624
00:25:44.430 --> 00:25:47.350
hole, uh, rather accurately, the shadow of a

625
00:25:47.350 --> 00:25:49.830
black hole, as Fred so eloquently explained.

626
00:25:49.830 --> 00:25:52.150
And I didn't understand one thing.

627
00:25:52.550 --> 00:25:54.710
Amongst others, of course, with the multiple

628
00:25:54.710 --> 00:25:56.750
observatories around the world and the use of

629
00:25:56.750 --> 00:25:58.550
atomic clocks to synchronize the data

630
00:25:58.630 --> 00:26:01.630
acquisition, why were they, uh, on

631
00:26:01.630 --> 00:26:04.420
tenterhooks, uh, regarding the weather

632
00:26:04.420 --> 00:26:06.740
at all the sites, with, uh, bad weather at

633
00:26:06.740 --> 00:26:09.060
just one, putting the whole venture in peril.

634
00:26:09.060 --> 00:26:11.580
I understand from the show and other sources

635
00:26:11.580 --> 00:26:13.780
that they were collecting radio wavelength

636
00:26:13.780 --> 00:26:16.220
data. And I thought that this was unaffected

637
00:26:16.220 --> 00:26:18.980
by the weather and atmospheric conditions. I

638
00:26:18.980 --> 00:26:21.700
thought that, uh, was the intrinsic beauty of

639
00:26:21.700 --> 00:26:23.820
radio astronomy. Day and night, rain and

640
00:26:23.820 --> 00:26:26.540
shine. Hope you can enlighten me.

641
00:26:26.620 --> 00:26:29.540
Wait for it. But over the radio. Dear,

642
00:26:29.540 --> 00:26:31.580
oh, dear. Uh, Andrew Broadhurst. Thank you,

643
00:26:31.580 --> 00:26:31.960
Andrew.

644
00:26:32.590 --> 00:26:33.950
Professor Fred Watson: That's a great question. Andrew.

645
00:26:33.950 --> 00:26:35.150
Andrew Dunkley: Leave the jokes to me, man.

646
00:26:37.710 --> 00:26:39.790
Professor Fred Watson: Yeah, well, I always leave them to you. So.

647
00:26:41.490 --> 00:26:42.910
Andrew Dunkley: Um, some to live. They're good.

648
00:26:43.390 --> 00:26:46.190
Professor Fred Watson: Oh, gosh. When was the last. Oh, never mind.

649
00:26:48.050 --> 00:26:49.950
Uh, Andrew's on the money. There is, you

650
00:26:49.950 --> 00:26:52.030
know, I thought radio waves were unaffected

651
00:26:52.030 --> 00:26:54.150
by the weather. And the answer is that radio

652
00:26:54.150 --> 00:26:56.910
waves come in different flavors. Uh, and

653
00:26:56.990 --> 00:26:59.190
so, uh, what you might call low frequency

654
00:26:59.190 --> 00:27:01.790
radio waves, um, which are still

655
00:27:01.870 --> 00:27:04.680
relatively, you know, they're way outside the

656
00:27:04.680 --> 00:27:06.880
medium wave band of radio and things of that

657
00:27:06.880 --> 00:27:09.520
sort. But low frequency in radio astronomy,

658
00:27:09.850 --> 00:27:12.600
um, I guess goes up to a couple of gigahertz

659
00:27:12.600 --> 00:27:15.280
or something like that. Um, those

660
00:27:15.360 --> 00:27:17.960
are largely unaffected by weather. That's

661
00:27:17.960 --> 00:27:19.680
absolutely right. So that's why it can be

662
00:27:19.680 --> 00:27:22.480
pouring down at Parkes, the radio dish there.

663
00:27:22.480 --> 00:27:24.000
And the astronomers are still happily

664
00:27:24.000 --> 00:27:26.720
observing through that. But the Event Horizon

665
00:27:26.720 --> 00:27:29.570
Telescope used higher frequencies. Uh, in

666
00:27:29.570 --> 00:27:32.010
fact, one of the telescopes that was

667
00:27:32.010 --> 00:27:34.850
incorporated into it was alma. The Atacama

668
00:27:34.850 --> 00:27:37.530
Large Millimeter Array, which has featured

669
00:27:37.530 --> 00:27:40.450
very, uh, very widely on space knots. That is

670
00:27:40.450 --> 00:27:43.290
a high frequency, uh, radio

671
00:27:43.530 --> 00:27:46.010
array. In fact, they have

672
00:27:46.090 --> 00:27:48.770
receivers that go up to, uh, more than

673
00:27:48.770 --> 00:27:51.330
900 gigahertz. So that's like, you know,

674
00:27:51.330 --> 00:27:53.890
nearly a thousand times higher frequencies

675
00:27:53.890 --> 00:27:56.170
than what we've just been talking about. And

676
00:27:56.170 --> 00:27:58.850
those sorts of frequencies, uh, the weather

677
00:27:59.010 --> 00:28:01.650
plays a very important role. Because water

678
00:28:01.650 --> 00:28:04.130
vapor actually dramatically

679
00:28:04.130 --> 00:28:06.930
absorbs the microwave signals.

680
00:28:07.250 --> 00:28:09.010
Andrew Dunkley: And that's what experience that watching

681
00:28:09.010 --> 00:28:11.090
satellite television. If there is a storm

682
00:28:11.810 --> 00:28:14.810
and it rains heavily, the wavelengths of the

683
00:28:14.810 --> 00:28:17.210
raindrops can absorb the signals from the

684
00:28:17.210 --> 00:28:18.450
satellite and you get nothing.

685
00:28:19.440 --> 00:28:21.610
Professor Fred Watson: Uh, that's interesting. I've never tried to

686
00:28:21.610 --> 00:28:24.040
watch satellite television. So that's, that's

687
00:28:24.040 --> 00:28:25.000
good thing to know.

688
00:28:25.420 --> 00:28:27.560
Andrew Dunkley: Um, it's one of the pitfalls.

689
00:28:27.800 --> 00:28:30.120
Professor Fred Watson: Yes, yes. In fact, I seldom watch television

690
00:28:30.120 --> 00:28:32.640
at all. So that's probably why. Um,

691
00:28:33.000 --> 00:28:35.960
but the bottom line is, um, you know, it's

692
00:28:35.960 --> 00:28:38.880
why facilities like ALMA and some

693
00:28:38.880 --> 00:28:41.480
of the other radio telescopes that were used,

694
00:28:41.900 --> 00:28:44.600
uh, to become the Event

695
00:28:44.600 --> 00:28:46.320
Horizon Telescopes, why they're all at high

696
00:28:46.320 --> 00:28:48.760
altitudes. Alma is at almost

697
00:28:48.840 --> 00:28:51.410
5,000 meters above sea level. Level,

698
00:28:51.840 --> 00:28:54.770
um, that's, you know, 15, 16,000ft.

699
00:28:54.770 --> 00:28:57.290
And at that height, there is very little

700
00:28:57.290 --> 00:28:59.770
water vapor in the atmosphere. Uh, but you

701
00:28:59.770 --> 00:29:01.770
can still get weather. And that's why they

702
00:29:01.770 --> 00:29:03.810
were indeed on tenterhooks about the weather.

703
00:29:03.810 --> 00:29:06.330
Because they don't want any of these, uh, if

704
00:29:06.330 --> 00:29:09.250
you lose one of those arrays, and

705
00:29:09.250 --> 00:29:10.810
I think there were eight of them that came

706
00:29:10.810 --> 00:29:12.810
together all around one hemisphere of the

707
00:29:12.810 --> 00:29:15.370
Earth, uh, to make up the Event

708
00:29:15.370 --> 00:29:17.530
Horizon Telescope. If you lose one of them,

709
00:29:17.680 --> 00:29:20.080
them, you lose a significant amount of your

710
00:29:20.080 --> 00:29:22.200
ability to reconstruct the image that they're

711
00:29:22.200 --> 00:29:24.760
seeing. Uh, and so that was why they were

712
00:29:24.760 --> 00:29:26.800
worried that the weather on just one of them

713
00:29:26.800 --> 00:29:29.760
might be, uh, moist, uh, or damper

714
00:29:29.760 --> 00:29:31.680
than they can cope with. And that would have

715
00:29:31.680 --> 00:29:33.160
screwed up the whole thing. But as it

716
00:29:33.160 --> 00:29:35.480
happened, it wasn't. It didn't happen. And it

717
00:29:35.480 --> 00:29:36.240
was great.

718
00:29:36.480 --> 00:29:38.160
Andrew Dunkley: They got global good weather.

719
00:29:38.480 --> 00:29:40.280
Professor Fred Watson: They did global good weather at these high

720
00:29:40.280 --> 00:29:41.960
altitude sites. That's right. The job.

721
00:29:41.960 --> 00:29:44.750
Andrew Dunkley: All right, there you are, Andrew. Uh, thank

722
00:29:44.750 --> 00:29:46.910
you for your question. And we've got one

723
00:29:46.910 --> 00:29:49.750
more. We'll squeeze in from John Sputh. I

724
00:29:49.750 --> 00:29:51.390
hope I pronounced that correctly. John,

725
00:29:51.390 --> 00:29:52.230
thanks for your question.

726
00:29:52.230 --> 00:29:52.590
Professor Fred Watson: Hi.

727
00:29:52.590 --> 00:29:54.510
Andrew Dunkley: I have a question that's been bugging me for

728
00:29:54.510 --> 00:29:56.990
some time and I need an expert to help me

729
00:29:56.990 --> 00:29:59.190
out. I think we should stop there. Fred.

730
00:30:00.150 --> 00:30:01.990
Professor Fred Watson: There's nobody here, is there? Who's that?

731
00:30:01.990 --> 00:30:03.430
Hang on. I'll go and see if I can find

732
00:30:03.430 --> 00:30:03.910
somebody.

733
00:30:04.310 --> 00:30:06.150
Andrew Dunkley: The cat could probably answer this one.

734
00:30:07.030 --> 00:30:09.990
Now, imagine, um, a spaceship traveling close

735
00:30:09.990 --> 00:30:12.110
to the speed of light. Disregarding that we

736
00:30:12.110 --> 00:30:13.910
don't have that sort of propulsion just yet.

737
00:30:14.310 --> 00:30:16.150
Would the increase in its

738
00:30:16.710 --> 00:30:19.670
relativistic mass at some point turn

739
00:30:19.670 --> 00:30:22.310
the spaceship into a black hole? And if so,

740
00:30:22.710 --> 00:30:25.430
would that spell the end of the ship and its

741
00:30:25.430 --> 00:30:27.950
crew? Or would they be able to slow down to

742
00:30:27.950 --> 00:30:30.710
reverse the process? What a great question.

743
00:30:30.790 --> 00:30:32.550
Professor Fred Watson: It is a fantastic question. Do you want to

744
00:30:32.550 --> 00:30:33.350
have a go at it?

745
00:30:33.660 --> 00:30:34.900
Andrew Dunkley: Uh, the answer is no.

746
00:30:36.010 --> 00:30:38.090
Professor Fred Watson: It is. You got right. Yeah, you're right on

747
00:30:38.090 --> 00:30:40.010
the money. They see. See, there is an expert.

748
00:30:40.010 --> 00:30:42.796
It's called Andrew Dunkley or Dave 50.

749
00:30:42.864 --> 00:30:43.690
Andrew Dunkley: 50 chance.

750
00:30:45.730 --> 00:30:48.650
Professor Fred Watson: Um, it's a great question. And it,

751
00:30:48.650 --> 00:30:51.450
it. The answer is a little bit, um,

752
00:30:51.450 --> 00:30:53.690
prosaic, I think. And that is that

753
00:30:54.250 --> 00:30:56.610
in the, in the rest frame of the

754
00:30:56.610 --> 00:30:59.250
spacecraft, you know. So if you're on the

755
00:30:59.250 --> 00:31:01.170
spacecraft and you're going at almost the

756
00:31:01.170 --> 00:31:04.030
speed of light, your mass doesn't change.

757
00:31:04.590 --> 00:31:07.230
It's only in the rest frame of

758
00:31:07.710 --> 00:31:10.230
a stationary observer. And by that I mean

759
00:31:10.230 --> 00:31:12.270
somebody watching you go past, somebody

760
00:31:12.270 --> 00:31:15.110
watches you hurl past. And your mass gets

761
00:31:15.110 --> 00:31:17.590
very much higher to the

762
00:31:17.590 --> 00:31:19.870
observer. But to the,

763
00:31:20.350 --> 00:31:23.270
the inhabitants of the spacecraft or the

764
00:31:23.270 --> 00:31:25.470
spacecraft itself, your mass doesn't change.

765
00:31:25.470 --> 00:31:25.870
Andrew Dunkley: It's.

766
00:31:25.870 --> 00:31:27.820
Professor Fred Watson: You're still normal. It is still normal.

767
00:31:28.290 --> 00:31:31.090
Yeah. And the same story is true with time

768
00:31:31.090 --> 00:31:33.850
dilation. You know that when you go

769
00:31:33.850 --> 00:31:36.530
nearer the speed of light, your clocks tick

770
00:31:36.530 --> 00:31:39.530
slower. Uh, that's a. Seen by a stationary

771
00:31:39.530 --> 00:31:42.370
observer. Uh, and so it's the same sort of

772
00:31:42.370 --> 00:31:43.809
thing. If you're on the spacecraft, your

773
00:31:43.809 --> 00:31:45.610
clock is ticking at the same rate as it ever

774
00:31:45.610 --> 00:31:47.690
was. But to a stationary observer, your

775
00:31:47.690 --> 00:31:48.850
clocks tick slower.

776
00:31:48.850 --> 00:31:51.010
Andrew Dunkley: And this has been proven with atomic clocks,

777
00:31:51.010 --> 00:31:51.490
hasn't it?

778
00:31:51.810 --> 00:31:54.170
Professor Fred Watson: It has. And indeed with mass as well. You can

779
00:31:54.170 --> 00:31:56.210
do this, you can see this sort of phenomenon

780
00:31:56.210 --> 00:31:58.920
with, um, uh. With uh,

781
00:31:58.920 --> 00:32:01.280
cosmic rays which travel very close to the

782
00:32:01.280 --> 00:32:02.520
speed of light. You can see their mass

783
00:32:02.520 --> 00:32:05.480
change. So, um, that's

784
00:32:05.480 --> 00:32:07.800
from the point of view of somebody who's, you

785
00:32:07.800 --> 00:32:10.000
know, not moving at the same speed. If you're

786
00:32:10.000 --> 00:32:11.920
moving at the same speed, you don't see any

787
00:32:11.920 --> 00:32:12.640
change at all.

788
00:32:13.680 --> 00:32:16.640
Andrew Dunkley: That's pretty boring. The more we Discuss

789
00:32:16.800 --> 00:32:18.840
black holes and the number of questions we

790
00:32:18.840 --> 00:32:21.760
get about them. People are really quite

791
00:32:22.160 --> 00:32:25.040
captivated by the strangeness of

792
00:32:25.040 --> 00:32:27.320
them. I suppose they throw up all these

793
00:32:27.320 --> 00:32:30.220
things that seem so alien to what we consider

794
00:32:30.300 --> 00:32:32.900
normal. Uh, and that's because we've only

795
00:32:32.900 --> 00:32:35.700
experienced um, what's happening on our

796
00:32:35.700 --> 00:32:38.660
planet at any given time. So to try

797
00:32:38.660 --> 00:32:41.380
and comprehend um, enough gravity to

798
00:32:41.380 --> 00:32:44.300
warp time to slow things down

799
00:32:44.459 --> 00:32:47.260
to the observer and increase mass. Just,

800
00:32:47.980 --> 00:32:49.020
it's really whack.

801
00:32:50.780 --> 00:32:53.740
Professor Fred Watson: Sad on the brain. That's true. But uh,

802
00:32:53.740 --> 00:32:56.060
look, John's question there is a great

803
00:32:56.060 --> 00:32:58.660
question because it's not intuitively

804
00:32:58.660 --> 00:33:01.610
obvious what is happening uh,

805
00:33:01.650 --> 00:33:04.010
in a situation like something traveling close

806
00:33:04.010 --> 00:33:06.810
to the speed of light. And it, and so he's

807
00:33:06.810 --> 00:33:09.570
right to ask would that mass actually turn it

808
00:33:09.570 --> 00:33:11.890
into a black hole? Uh, but the answer is no

809
00:33:11.890 --> 00:33:13.370
because of the reasons that I've outlined.

810
00:33:13.370 --> 00:33:14.610
But it's great, great thinking.

811
00:33:14.610 --> 00:33:16.490
Andrew Dunkley: It is indeed. Thank you John. Thanks for the

812
00:33:16.490 --> 00:33:18.330
question. Do appreciate it. Keep your

813
00:33:18.330 --> 00:33:20.650
questions coming in. We're trying to um, run

814
00:33:20.650 --> 00:33:23.570
them down but they, it's, it's, it's an ever

815
00:33:23.570 --> 00:33:25.360
growing mass really.

816
00:33:25.360 --> 00:33:27.760
Professor Fred Watson: It's. All right, look, as you said earlier

817
00:33:27.760 --> 00:33:30.120
Andrew, um, all the space nutters are going

818
00:33:30.120 --> 00:33:31.760
to get together and sort them out for

819
00:33:31.760 --> 00:33:33.720
themselves and we'll be, that'll be

820
00:33:33.960 --> 00:33:34.520
encouraged.

821
00:33:34.520 --> 00:33:36.840
Andrew Dunkley: Actually if uh, people want to ask questions

822
00:33:36.920 --> 00:33:39.600
of the group uh, and discuss it,

823
00:33:39.600 --> 00:33:42.280
they. Yeah, by all means. Um, that, that's

824
00:33:42.280 --> 00:33:44.080
part of the reason we set up the Space Nuts

825
00:33:44.080 --> 00:33:46.880
podcast group. So um, it's a good opportunity

826
00:33:46.880 --> 00:33:49.840
to not only meet like minded people who enjoy

827
00:33:49.840 --> 00:33:52.160
these, these topics, but also to maybe come

828
00:33:52.160 --> 00:33:54.020
up with your own ideas on, on what might,

829
00:33:54.170 --> 00:33:55.970
might be and you know, I'll keep an eye on it

830
00:33:55.970 --> 00:33:57.570
and if something pops in there that we think

831
00:33:57.570 --> 00:34:00.090
is worthy of further discussion, we will

832
00:34:00.170 --> 00:34:03.090
certainly investigate that. Thanks

833
00:34:03.090 --> 00:34:05.490
to everyone who um, who sent in their

834
00:34:05.490 --> 00:34:08.450
questions, uh, and uh, contributed and joined

835
00:34:08.450 --> 00:34:10.930
the Space Nuts podcast group and Patreon and

836
00:34:10.930 --> 00:34:13.140
everything else. We really appreciate it. Uh,

837
00:34:13.210 --> 00:34:15.210
but most of all we appreciate you Fred. Thank

838
00:34:15.210 --> 00:34:15.770
you so much.

839
00:34:16.330 --> 00:34:18.730
Professor Fred Watson: It's a pleasure, thank you for having me as

840
00:34:18.730 --> 00:34:19.050
always.

841
00:34:19.290 --> 00:34:22.059
Andrew Dunkley: And we will catch you next week. Professor

842
00:34:22.059 --> 00:34:24.779
Fred Watson, uh, astronomer at large and from

843
00:34:24.779 --> 00:34:27.099
me Andrew Dunkley. Thank you again and we'll

844
00:34:27.099 --> 00:34:29.539
catch you next time on another edition of

845
00:34:29.619 --> 00:34:32.339
SpaceNuts. Uh, you'll be

846
00:34:32.339 --> 00:34:34.579
listening to the Space Nuts podcast

847
00:34:36.099 --> 00:34:38.899
available at Apple Podcasts, Spotify,

848
00:34:39.059 --> 00:34:41.819
iHeartRadio or your favorite podcast

849
00:34:41.819 --> 00:34:43.579
player. You can also stream on

850
00:34:43.579 --> 00:34:45.299
demand@bytes.com.

851
00:34:45.619 --> 00:34:47.659
Professor Fred Watson: This has been another quality podcast

852
00:34:47.659 --> 00:34:49.779
production from bytes.com.