Cosmic Questions, Gravitational Waves & Dad Jokes from the Universe

don't understand them. But, that's the nature of the jokes because Judd wants Fred Watson to explain why they're funny. So we'll get it. We'll get to that and much more on this episode of space nuts.

Yeah. Professor Fred Watson: Excellent. It's very good news. yes. good to see you, Fred Watson. By the way, thanks for joining us. Professor Fred Watson: I was passing by, I thought might as well. Yeah, I couldn't do this without you because, I would have no idea about some of the answers to these questions. But, we might as well just go straight to it. And our first question comes from sunny California.

Rennie wants to know, theoretically, can gravitational waves pick up any kind of subatomic particles or larger objects and carry them for a certain period of time and drop them off as they get weaker? Kind of like a surfer catching a wave. Now, gotta tell you, in one of my science fiction novels, I did this exact thing. Although it wasn't a small object. It was a space battle cruiser that got picked up by a neutron bomb

explosion which created a gravitational wave. But that's another story, and it's science fiction, so I could do whatever I like. But, yeah, that's a good question. can they pick anything up and carry it for a distance? Professor Fred Watson: Well, no. apparently not. I checked this one up, a while ago, and, so gravitational waves are a deformation of spacetime. And, objects, feel them, because that's how we detect them. The fact that the Shape of space changes slightly as a

gravitational wave passes through. it's, basically a vibration of space time. and we detect that by. Well, one way of detecting it is by using two mirrors, four kilometres apart in the case of ligo, the, Laser Interferometer Gravitational Wave Observatory. two mirrors whose separation can be measured to, what is it? 1 10,000th of the diameter of a neutron, I think a proton. Wow. Professor Fred Watson: It's ridiculous. Yeah, ridiculous.

But that's what you need, because the. As we've talked about before, the, In fact, I think we mentioned this last week, the flexibility of space is very, very low. It's very stiff. 100 billion billion times the stiffness of steel if you use Young's modulus as a yardstick. so, But space does vibrate. but, that's what happens. So it vibrates as the wave passes through, but you don't get surfed by the wave. You know, it doesn't pick things up and carry them with

it. That's. Which is Rennie's point, I think, things feel its presence, they feel it by the vibrations that it sets up, but they stay put. And that's just as well, because, you know, the Earth's being bombarded by gravitational waves all the time. We really wouldn't want to be carried away, from our neat and tidy orbit around the sun by passing through. But, you know, what you've just done? You've debunked my book. Professor Fred Watson: Well, that's. I, wasn't going to mention that.

However. However, I. I will. I will qualify by saying it wasn't, you know, a standard gravitational wave. Professor Fred Watson: That was the neutron bomb. Gravitational. Created by human action. So, you know, I might get away with that one, but, Yeah, So you did say they're hitting us all the time. Because I remember when we first talked about gravitational waves being discovered, it seemed like a rare event, but it's not.

Professor Fred Watson: No, that's right. And in fact, you and I have spoken about the sort of background noise of gravitational waves that m. Swirling around, the planet all the time. and yes, it's just as well that space is so stiff, because otherwise we'd be getting rattled pretty badly all the time by gravitational waves. Nice. Well, okay, good. Other things can rattle us.

Professor Fred Watson: Yes, they can. And that neutron bomb explosion might, actually rattle us to the one you were talking about in your book. But that would be a shockwave, not a gravitational wave. Yes, indeed. All right, thank you, Rennie. Lovely to Hear from you. Rennie's one of our regular contributors. Our next question comes from yet another regular contributor. His name is Rusty. G' day, Fred Watson and Andrew. It's Rusty in Donnybrook. Now we know that in the realm of physics, human

logic often goes awry. Here's a try anyway. Thinking about the Big Bang, initially, no matter came out of it. It was, was all energy. And most of this was in the form of space time. Looking at, black holes, which is the opposite. This is matter going into a black hole after the event horizon. And when it finally gets to the singularity, it can't exist as matter. So it must exist as, matter's equivalent, which is energy. We also know that space time can rotate. We've seen, photographs

now of frame dragging. And we know that it even exists, around the Earth. So we've got some interesting things there about space time. It has mass, it can rotate. So is this energy dark matter? It must also have a mass equivalence if it's got energy. So, if it is dark matter, could that be. Could it be the rotation of space itself on a galactic scale influencing the rotation of spiral galaxies? That's my question. Pretty difficult day. Okay, cheers. Yeah, yeah. Rusty, you love asking

these curveball questions. I know. I, think you sit there trying to figure out what to throw at us next. this is an interesting one. We have talked about the rotation of space time before or whether or not it does, dark energy is always coming up. And we spoke about a new theory on, dark matter in our last episode. And we keep sort of cross referencing dark matter and dark energy. But, yeah, okay, so, does space time rotate? The mass of space time, could that be dark matter?

I think I precede that too much. But anyway, that was the guts of the question. Professor Fred Watson: So, the energy that the universe contained at first, was photons. It was electromagnetic energy, and they then basically collapsed into matter. So the Big Bang was very efficient at that process. when things cooled down a bit. when something crosses the event horizon, goes into a black hole, it remains as matter, even though it's now been squashed into an

infinitesimal point. so the material content of a black hole, is mass. It's matter because it increases its mass. we know that mass and energy are related by E equals MC squared. Rusty certainly knows that. so, I'm just, I'm not sure I'm following the logic there. We do know, that, we've had this issue with the asymmetric, sorry, the unequal rotation of galaxies clockwise and anti clockwise, that seem to be more one way than the other. And that has raised the suggestion that

the universe is rotating. And it turns out if it rotates once every 500 billion years, then you can get rid of the Hubble tension. I think that's the bottom line there. And so, I mean, you know, Rusty's points are all well made. I don't think we get rid of dark matter and dark energy though, by those considerations. I think we're still stuck with puzzles that we don't understand.

Yeah, I don't think he was talking about getting rid of dark matter, but he was talking about the mass of space time being dark matter. Professor Fred Watson: Yeah, sorry, I'm using the wrong words there. I'm using my words. that's all right. Professor Fred Watson: Very loosely, yes, that's right. But dark matter, is, you know, it's clumpy. It's not, something that is equal throughout the universe, which if it was space time, it would be. I mean

space time itself doesn't have mass. It's the fabric within which mass, within within which it exists. So I, think it's an interesting suggestion, as rusties always, are. But I'm not sure that works out. Throwing the equation of state there, that'll do it. Oh yes, Talking about that last episode. Yes. Oh, gosh, here we go. The headache worthy material, this. Professor Fred Watson: Yes, that's right. when you talk about the universe and space time, like space

time, you said it doesn't have mass. It's just everything that's in it is what's mass? Is it strung out evenly across a, universal plane or it's not evenly spread 360 degrees in all directions, is it? Professor Fred Watson: Well, it more or less is. But you're right, it changes from one place to another because math matter changes the shape of space time. so if you've got a lump of matter, then you're distorting the space around it and yes, frame

dragging. Something, that Rusty mentioned. Frame dragging is the way a rotating object drags the space time around with it. But even if it's not rotating, it's still deforming the space time around. It's how gravitational lenses work. And so space space time is this crinkled pattern of irregularity that comes from the matter within it. And we think what we call the cosmic web, this entangled web of almost like a foam of dark matter that itself has

mass and changes the shape of spacetime. That's how we think the galaxies formed and how we think we got the structure that we see today. but you need mass within space time in order to get those phenomena. Gotcha. All right, thank you Rusty. stirring the pot as always. This is Space Nuts Andrew Dunkley here and Fred Watson Watson just he's right next to me. Now let's take a quick break from the show to tell you about our sponsor Insta360 and their brand spanking new top of the line

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Dave's in Indiana, which is also the name of my sister in law's cat. if you fire. I don't know why I said that. If you fire a laser into space, would you the emission impart a force in the opposite direction? If not, could a broad beam be used on a space sail to effectively move a spacecraft? thank you, Dave. we have talked about this concept before. They're talking about experiments of spacecraft using interstellar sails or whatever you want to call them, being pushed

along by laser. I don't know if they've actually done it yet or maybe they've tried it in small scales. I can't remember. We have come across this before. Professor Fred Watson: There was some research that was published and we talked about it on Space Nuts probably a couple of years ago now in fact it might even be longer which demonstrated that a light sail will actually provide an acceleration to a spacecraft. I think this was using sunlight if I remember rightly. But there's a spacecraft

that was just an experimental one. They used a light sail. They could tilt it in different directions and it basically provided accelerations exactly what they expected from the transfer of momentum from the photons to the sail itself. so, yes. And the answer is yes. So there is a whole study, Dave, looking at this, the project is called Breakthrough Starshot.

I'm not sure whether it's still running but the idea was to do a feasibility study, funded by a Russian billionaire called Yuri Milner, under the Breakthrough Foundations, ah, Aegis. They were basically doing a feasibility study to see whether you could use powerful lasers to fire photons at a light sail and accelerate a spacecraft to maybe half the speed of light, maybe a little bit less, but certainly a significant fraction of the speed of light by bombarding

it with these photons all the time. to see whether you could get it to Alpha Centauri, or Proxima Centauri, the nearest star to our solar system, in a reasonable time. In other Words, you know, decade or so, rather than the 60,000 years it would take using conventional rockets. So it has been well looked after. So, your idea is good and is already, you know, already in train and in fact has already been demonstrated by this experiment that was, carried out in Earth orbit.

And if you were to fire a laser into space, there would be no recoil, there'd be no backwash or whatever you want to call it. Professor Fred Watson: I think that's correct, yeah. I need to check that, but I think that is correct, because, yes, you wouldn't want your blazer firing off in the opposite direction. It's not, it's not like firing a bullet. it shoots from shooting light. there's no recoil from a torch or a flashlight. Professor Fred Watson: Well, but yes, I mean, there might be.

Yeah, I think that is correct. I think that's correct. Yeah. Professor Fred Watson: You'd never detect it in a torch anyway. No, definitely not. I have just done a bit of a search and I found a website called planetary.org and this is an organisation that is working on light sail technology, through the Planetary Society. And, they're doing a light sail programme and they demonstrated that solar, sailing is a

viable means of propulsion. And for small satellites, solar sails, use sunlight instead of rocket fuel for propulsion. they are one of the few technologies that could be used for interstellar travel. Their Light Sail 2 spacecraft was, in space from June, 2019 to November 2022 and successfully used sunlight, alone to change its orbit around Earth. So that's probably what you were thinking of. Professor Fred Watson: It is, yes, that's right, yeah.

So that's a website worth visiting, Dave, if you want to check it out. Planetary.org but there are so many other stories about lightsail technology and lots, of people giving this very, very serious thought. So, worth worth chasing up if you want to find out more about it. And thank you, Dave, for the question. Space nuts. Now, final question is not a question at all. Excep. It's a question that needs to be answered. Doesn't make sense. But, Judd, who, is in Brisbane, formerly Sydney,

the traitor. Traitor, says. G' day, Andrew and Fred Watson. Heidi did a great job of, co hosting while Andrew was away. It could take years for her to bring her dad jokes to Andrew's level, though. Yes, that's very true. you know, there's no comparison to how bad I am. I, came across this zinger online. He says, if you use it, maybe Fred Watson could explain why it's funny. that always goes down, down well with my wife. He says. All right, here we go. Two spinal. spinal.

Two spiral galaxies walk into a pub. The first one goes up to the bar and asks for two drinks, one for him and one for his friend. The barman looks suspiciously at the second spiral galaxy and says, I'm sorry, but I can't serve your friend. He'll have to go. The first spiral galaxy complains, why can't you serve him? The barman replies, he's barred deafening silence. Why is that, Fuzzy? Professor Fred Watson: I'm chuckling away to myself here. Ho, ho, ho, ho, ho, ho. So, it's really interesting.

There's three different, three different uses of the word bar here. Ah, the bar. The barman's got, and a bar being something that prevents you from doing something new Bard. But also, we talk about spiral galaxies having a bar. I kind of figured it was something. Professor Fred Watson: Like that by that sort of bar. think of a chocolate bar this time. spiral galaxies that rather than just having a central bulge with spiral arms coming from them, they've got the central

bulge, but they've also got a bar across. And the spiral arms start with the. From the ends of the bar. indeed. Our own galaxy has one which has been observed and measured by the Gaia spacecraft and many others. So our galaxy has one. We sort of look at it sideways from our vantage point, or obliquely, if I can put it that way. it's a, you know, it's a phenomenon that is very common among galaxies. We, call them barred spirals. There you are.

Professor Fred Watson: They are spirals. So your friends are bad. Your friend's bad. That's because he's a bad spiral. Sorry, it took a long time to get that through. No. Well, it certainly required explanation. I'm sure some people immediately went, oh, yeah, I get it. but, others like myself would have gone, I don't. Yeah, I'm scratching my head. although it's prompted another dad joke. You ready for this, Judd? so the Milky Way can't. Here we go. Is non

alcoholic. Because it's. It's barred. Professor Fred Watson: Yes, it's bad spiral. Yeah. Terrible, horrible joke. thanks, Judd. Oh, he had a bonus joke. the. The bartender says, I don't serve anyone. Faster than light, a neutrino walks into the bar. Why is that funny? Professor Fred Watson: So that was when, it's a story. It's quite an entertaining story, which we covered. This

is going back maybe even a decade, right? there is A particle detector at Gran Sasso in Italy, northern Italy, which detected neutrinos that were being emitted by the Large Hadron Collider on the French Swiss border. Now, I remember neutrinos barely interact with anything, so they travel through rock, cheerfully go right through the,

Earth, no problem. But the, problem was these neutrinos seemed to arrive at Gran Sasso, in a time that was less than what it would take them if they were travelling at the speed of light, which is about the speed that they do travel. They travel very close to the speed of light. Right. Professor Fred Watson: And so, this was, it really hit the headlines big time. Faster than light neutrinos. And, you know, people commented on it. There were relativist theories, people

digging up what could be going on here. They were all trying to think of how the theory of relativity could be modified to accept this, to make it work. And a few other people were saying, I bet it goes away. I bet there's something wrong with the equipment. About a month after that experiment had been reported, they fessed up at Gran Sasso that they had discovered a faulty connector.

and it was that faulty connector, that was giving the, mistaken impression that these neutrinos was travelling faster than the speed of light. It's to do with their clocking. And it was so embarrassing that the director is. He resigned to. Resigned, yeah. Wow. I mean, we've, we've talked about certain gaffes in science, discoveries, etc in the past, but that, that's a, that's a big price to pay, isn't it?

Professor Fred Watson: It is, yeah. Yeah. He was, I think he felt that, he'd have put Italy on the scientific map for the wrong reasons because they had a faulty connector. But it does remind me of another joke that was going on round about the same time. This was back in 2012 when the Higgs boson was discovered, which I always liked. and it's very quick. A Higgs boson walks into a bar and. No, let me start again. That's the wrong joke. Wrong joke. That was funny.

Professor Fred Watson: That was funny. That was good, wasn't it? A Higgs boson, a Higgs boson walks into a church and the priest says, I'm sorry, we don't allow Higgs bosons into this church. And the Higgs boson said, well, how do you have mass there, then? Love it. I have heard that before. Professor Fred Watson: Yes, I'm sure you have, yeah. Was doing the round.

I've got a, somewhat spacey joke because, GPS operates using global positioning satellites. I'm going to buy you one of these, Fred Watson. This is, a GPS navigation system for seniors. Professor Fred Watson: Okay. It, not only tells you where to go, is how to get there. It tells you why you wanted to go there in the first place. Professor Fred Watson: Yeah, that's a good one. It probably needs to tell you where you've come from as well and how to get back.

I'm, not quite at that stage yet. My GPS gets used a lot and I always know why I'm going there. Although sometimes I do wonder. Well, it's reached a point where we wonder how we dealt without. Professor Fred Watson: It is amazing, isn't it? We used to have those big, thick roadmap books in the car. Professor Fred Watson: Yeah. I used to have them on the passenger seat with page markers in them so I

could, you know, when I got to that end of. End of one map, I could turn it over and find where I was on the next. Terribly dangerous. Yeah, the way it was. You're not allowed to touch your phone in a car, but you can read a book. Professor Fred Watson: Yes, that's right. Yes. Yeah, it's, it's. Yeah. And, for all you young people, they used. It was made of paper with coloured maps inside. It was very, very. Professor Fred Watson: Some of them anyway. And in. Professor Fred Watson: Great.

And instead of it following you along on your phone, you just ran your finger along the red line. Okay, I gotta turn left there. Yes, all right, we're done. Fred Watson, thank you so much. Professor Fred Watson: It's a pleasure. and we will talk again soon, I hope. Yes, yes. I think I've got one more recording session before I head off and hand over to Heidi again for a while. But, I will be reporting in from my various destinations around the world. So, we'll, tell you

more about that down the track. Don't forget to visit us online too, because we need some more questions. we are desperately short, as it turns out. Cleaning out the closet of questions was probably a bad idea. But anyway, it got done. SpaceNutspodcast, uh.com Space Nuts IO is where you can send us your questions on the AMA link, audio or text. Either way, tell us who you are and where you're from. We love to know that. And, Huw in the studio.

well, I think you'll know where this is going. He couldn't be with us today because he's barred and from. From me, Andrew Dunkley. Thanks for your company. We'll see you on the next episode. Goodbye.