May 26, 2022

Inbound - Asteroid 73351989JA

Space Nuts Episode 306 with Professor Fred Watson & Andrew Dunkley
•Two near-earth asteroids that we’re keeping an eye on
•The Hubble Constant and our ever-expanding universe - issues have arisen, that are mystifying cosmologists. Fred has the...

Space Nuts Episode 306 with Professor Fred Watson & Andrew Dunkley
•Two near-earth asteroids that we’re keeping an eye on
•The Hubble Constant and our ever-expanding universe - issues have arisen, that are mystifying cosmologists. Fred has the details.
•Listener questions – We have questions about white holes and another about gravity Fred has the answers.
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Speaker A: Hello. Once again, thanks for joining us on Space Nuts. My name is Andrew Duncley, your host. And on this week's program, episode 306, we're talking asteroids. There are a couple of asteroids in the news. There's the one that's going to pass us by in the next few days. It's humongous. And there's another one that NASA is asking for help with. And we'll tell you why. There's also uh a lot of discussion on at the moment about the Hubble constant. They're trying to figure out the expansion of the universe and why it is happening the way it is and what exactly is happening. And the numbers don't stack up, but they think they've come up with a reason why. So we're going to look into that. We'll also answer some questions about white holes and gravity. That's all coming up on this week's episode of Space Nuts. 15 seconds. Guidance is internal. Ten, nine. Ignition sequence.

Speaker B: Uh.

Speaker A: Astronauts report.

Speaker C: It feels good.

Speaker A: And joining me, as he does each and every week without fail, because he is chained to his desk like a good public servant should be, is Professor Fred Watson, astronomer at large. Hello, Fred.

Speaker B: Hi, Andrew. How are you doing?

Speaker A: I'm good. You're still around after a change of government. That's good to see.

Speaker B: So far, so good. Yeah. Although, um as we speak, I'm just apologizing for a meeting that's going to make that's because I'm talking to you.

Speaker A: Well, I feel very important now.

Speaker B: There you go. Yeah, it's an important meeting, too, but not as good as this.

Speaker A: Yes. And before we get down to business, you fell off your bike.

Speaker B: Yes, I did.

Speaker A: You should never tell me things off camera.

Speaker B: No. You think for somebody who is interested uh in a topic, namely astrophysics, that absolutely centers around phenomenon of gravity, you'd think I'd understand it and understand that if you try and stand upright on a Hill after you're trying to get off your bike because the damn bike stands falling down on you, you'd get off the right side of the bike so that you were kind of facing up the Hill rather than down, because down tends to keep on going, which is what I did yesterday. Uh i got a very sore hip at the moment, but we're selling one piece.

Speaker A: All right. Uh well, that's probably just as bad as what I did yesterday. I stabbed myself. All right.

Speaker B: There you go.

Speaker A: Right on the point of finger with a pair of scissors. I was trying to open one of the Salvo's donation buckets for the Red Shield appeal because my law in New South Wales have to be sealed and we seal them with zip ties. And I was trying to leave the um scissors underneath the zip tie to prize it up and cut it. And it slipped and went straight into the tip of my finger right near the fingernail. I lost a lot of blood. I feel very faint now.

Speaker B: Yes. You would probably made a mess of everything you were trying to handle as well. Yeah.

Speaker A: I didn't bleed on anything but myself. I'm very good at holding back the flow. But we're all well now. We're all good over invented bandaids deserves a medal.

Speaker B: Indeed. That's right. But it doesn't say much for our uh respective competency. We are not sorted out when we're in our preschool here.

Speaker A: Yes, indeed. Now, Fred, let's talk about asteroids. The first one we need to talk about is asteroid seven three. 3519, 89 Ja. Because it's going to pass the planet in the next few days. And for those who sort of taken an extra week to listen to this podcast, it's already happened. But it will happen Friday, technically speaking. And it is a big one about 1.1 mile across or something.

Speaker B: Yes, that's right. Getting on um for 2 km, Andrew. And that's definitely a killer on that uh size. The rule of thumb that the asteroid world uses on the near Earth asteroid world is 100 meters uh asteroid is the same as 100 megaton nuclear weapon in the atmosphere. So imagine something 20 times that uh size. It's um nationwide devastation. I think an asteroid well known, very well known when it was discovered. In fact, it was discovered by somebody that I used to know, Eleanor Helen, who was very prolific asteroid observer at the Panama Observatory in California. And she spent time working at uh the United Kingdom Schmidt telescope that I used to be stronger in charge of. So she came over would have been the late 80s when she was over with one uh of our students, a uh young man called Bobby Boss, who I think became quite famous in this world as well in the asteroid world. So, yeah, it's a near Earth object. It's trajectory which took it or takes it close to Earth is still quite relaxed in the sense that it's eleven times the distance of the moon is the nearest that it gets. Sorry, it's about more than 3 million, something like that. So it's not going to do anything. But it's always a salient thing to take note of the fact that these things are charging around uh in our vicinity. It is classified as a PHA, a potentially hazardous asteroid. And it's one of these objects that is now monitored very assiduously, in fact, by NASA's center for Near Earth Object Studies. It's very much on the horizon. So a news item that shouldn't cause any kind of distress in the sense that it's a good news story because we know about these things now, which we didn't a long time ago when things just came flying at us from space. Gave Comets a bad name, gave asteroids a bad name. As I said, good news story.

Speaker A: I've uh read a few stories about it in the popular press and of course, a few referring to it as a near miss or we're avoiding disaster. All those sorts of headlines to try and make you read it. I thought the funniest one though, was where they were trying to make people understand how big this is. If you say 2, whatever number it turns out to be, people go, I can see that far, um but one article reported it as being double the length of the Burj Khalifa, the tallest building in the world. Now, that's probably a fair assessment, but the one that made me laugh was the one where I think they're trying to I don't know if it's desperation or if it was a headline they thought would just grab your attention, but 350 times the size of a giraffe.

Speaker B: Usually it's elephants. Andrew, I was out of the Zoo.

Speaker A: Last week and I was looking at the giraffes and I didn't kind of equate them to asteroids.

Speaker B: No, I don't really get that because how can you imagine something 350 times that size?

Speaker A: That was exactly what I thought anyway. Well, it got my attention, so I suppose that's why. Okay, so that's happening on Friday. Will we be able to see it?

Speaker B: Uh there will be. The problem with asteroids near Earth asteroids is that they move through the sky so quickly when they're close by. And amateur astronomy telescopes, which is what you need to do something like that, are not really tuned usually to things going that fast. It's just a slightly different way to Mount.

Speaker A: I don't think I could wiggle my knobs fast enough.

Speaker B: Yeah, well, that's right. Yes, it's knob wiggling. It's usually electronic knob wiggling. You need to essentially put in the coordinates. Having said that, that segues rather nicely to the next story, which is much smaller object that NASA knew was in our skies. Another potentially hazardous asteroid, this one, 2012 UX 68, on the 15 May, 10 days ago, as we speak now, was within two lunar distances of our planet. So that is in the region of seven to 800,000. Its close approach actually took place while Hemisphere was facing the asteroid. And so NASA uh were very keen for observers in Australia and New Zealand uh to actually try and get some imagery of it, because what you need is uh a fix on it. It's positioned at any given instant so that you can refine its orbit and you can know just to uh the extent to which this close approach has actually altered the orbit of the asteroid. So there was an alert uh from NASA's, JPL, and actually in collaboration with our national science agency, the CSIRO, which was responded to by scientists at the University of New South Wales, actually, I think they're campus in Canberra, Canberra Space, which is one of their departments, and in collaboration actually with colleagues in New Zealand, that worked out well because the weather in Australia was pretty rubbish, as it has been for about the last six months.

Speaker A: I know.

Speaker B: Uh whereas New Zealand, they got some good observations of it. This object is much smaller than the one we've just been talking about. It is 70 meters or thereabouts, but still big enough to be a worry if something like that impacting the Earth. Actually, you're talking about a Tunguska event, something that could demolish a fairly large area of vegetation, for example, as the Tunguska asteroid did back in 1908. Was that right?

Speaker A: Yeah, sounds familiar.

Speaker B: Yeah. I guess these stories are just reminding us that we live in a fairly busy part of uh the solar system. Space is big, of course, so that this is as good as a mile. But as I said before, the great news is that there is an entire industry now, which is an asteroid watch, if you put it that way. And just as a post script to this, we had some interesting correspondence recently with scientists about trying to get some Australian involvement in the Dart mission. Remember Dart, that's the double asteroid redirection test. It's a NASA uh probe which is on its way to an asteroid called Diddy Moss, which is a double asteroid. And what they're trying to do is take a swipe at Diddy Moss's moon to just change its orbit slightly and then check what has happened, just to see basically what the effect of clouding an asteroid is. Didymos has a moon called Amorphous, which is, I think it's only a few meters across. I can't remember the numbers, but yeah, we're interesting possibility that maybe we in Australia might get involved with some uh of the observations that might be needed for actually quantifying how much of an impact, how much of a move that has made that the impact has made on the asteroid dimorphis.

Speaker A: Okay, well, that will be interesting. That's a very exciting project. It does also make me wonder, Fred, if even with asteroids that we know about and that are documented and we know where they're going to be in years to come, what's to stop them being hit by something in the outer reaches and being knocked onto a collision course with Earth.

Speaker B: Yeah, well, it could happen. That's right. Usually um these things continuously monitored to uh the extent that you can sometimes they get lost, they just go so far away from us that you lose them, because we're talking about things fairly near the limits of detectability these small objects, although we basically found things down to 10 meters in size of the Earth. So it's a tribute to the kind of technology that we have these days and also um to the will within the scientific community to devote resources to this, because in a sense, it's civil defense. So uh there is a pretty strong mandate for doing that. But as I've told you before, on the periphery of the beginnings of this sort of study with two of my colleagues in Edinburgh, Victor Club and Bill Napier, who are among the first to recognize that the Earth's history has been affected by impacts and may continue to do so.

Speaker A: Yeah, well, we only talked about one a couple of weeks ago in China, wasn't it?

Speaker B: Yes, that's right.

Speaker A: Watch with interest. And if you've got the gear and you're an amateur astronomer. Maybe you'll be able to track 1989 Ja later this week. This is Space Nuts. You're with Andrew Dunkley and Professor Fred uh Watson. Let's take a short break from the show to talk about our sponsor, NordVPN. A virtual private network is an excellent way of protecting your private and business data from hackers and even your own government. But not all VPNs are the same. Some have poor encryption and some just slow you down. That's not the case with NordVPN. They uh have the best security in the business, and their Internet servers won't slow you down. In fact, there are times when connecting to NordVPN will be faster than uh your normal Internet connection. Don't ask me how, but it's true. I've seen it myself. And Nord has some big name organizations to back their claims, like Wired, Forbes, BuzzFeed, and even the BBC and a few others. The bottom line is that once you connect your device and that includes computers, phones, tablets, TVs, just about anything that goes online, your Privacy is assured. You're protected from criminals and surveillance. And you're not geo blocked either. It's reliable with 24 hours, seven day tech support and a 30 day money back guarantee. They believe they are the best in the business. And from my experience, it's true. Now, as a Space Nuts listener, we have a special URL for you to access NordVPN and grab a very special deal, Space Nuts, where you can use the special code Space Nuts to get NordVPN with benefits, uh a two year plan heavily discounted, giving you access to their high speed. And when I say high speed, ten gigabits per second servers in 60 countries with security for up to six devices. So check it out, Space Nuts and use the code Space Nuts to grab this exclusive deal to Space Nuts listeners, Um spacenuts. Now back to the show.

Speaker D: Space Nuts.

Speaker A: Now, Fred, from asteroids to the Hubble constants. Now, this is something that I guess we need to explain first up, but there's a lot of work going into understanding this. And a 30 year Hubble study from the Hubble Space Telescope has come up with some data, but uh it's also created more questions. But then there's another study that seems to have potentially come up with answers to those questions. So let's start at the beginning. What is the Hubble constant?

Speaker B: It's the number that essentially uh determines what the expansion of the universe is at the moment. Today, it's usually called H Naught. H being for the Hubble constant, the Naught is a uh subscript, which means that it's the Hubble constant now compared with what it might have been some time in the past. And once again, hopping back to when I was a young astronomer in Edinburgh back in the 1970s. And value for the Hubble constant was one of the biggest unknowns at the time. The way you measure it and it's the way Hubble did was you look at galaxies and you measure their velocity of recession, how uh fast they are moving away from us. But then you've got to have another indicator that tells you how far away they are because it's by the Hubble constant essentially relates that uh expansion velocity, the recession velocity of a Galaxy with its distance, the further away it is, the faster it's moving away from us. And so the trick is finding the means to measure the distance and the standard yardstick stick for that, a set of variable stars which are called Cepheid variables whose light varies in a way that we understand very well. And we know what their intrinsic brightness is. It goes up and down, but you can take an average and we know what it is, and it depends on what's called the period of oscillation of these things, how regularly, what the interval is between one maximum and the next. That's basically how they work. So that fairly complicated set of work led in the quite different estimates of the Hubble constant. There were two opposing groups, very, very polarized, one of which, if I remember rightly, led by Alan Sandy, said it was about 50, and I'll say a bit about the universe units in a minute. The other one, there was a fairly big group. I think Shahad de Vokula was one of the astronomers in that group, and there were others, too. The names will come to me in a minute. They said it was 100. So you have these two values, 51 hundred, differing by a factor of two, with two groups swearing blind that that was the answer. So what was the remedy to try and solve this conundrum? Well, it was built a space telescope which was eventually launched in 1990. We call it the Hubble Space Telescope, and that's why it was built essentially to resolve this issue by making very accurate observations of these Cepheid variable stars in not just our Galaxy, not just the neighboring galaxies, but ones that are relatively distant. And by the turn of the Millennium, that had been done, and the various teams, I think there were two teams that looked at it, probably inheriting the mantle of those earlier two teams from the they reached a consensus that the Hubble constant was known then to an accuracy of 10%. And the answer was 72, which is pretty well half way, not 42. But if you take the average of 51 hundred, you don't get as far off 72. 75. So 72 plus or -8 km/second, what are the units? Something a little bit abstruse. They uh are in kilometers per second per megaparsec. Now a uh megaparsec is essentially 3.2 or thereabouts million light years. Because a Parsec is the unit of distance that astronomers use. We don't really use light years, although light uh years are a very convenient way of expressing distances. One Parsec is the distance of an object that uh has a parallax of one arc second. Hence the name a Parsec. And it's what you actually measure because parallax is something you determine by the Earth's orbit around the sun. So one Parsec turns out to be roughly 3.2 light years. And so a mega power. Second, a million Parsec is 3.2 million light years. What the Hubble constant means 72 megapar. Second, it means that for every megaparsec further out you go, the recession velocity, the speed that a Galaxy is disappearing, increases by 72 km/second. Okay, so that's essentially the Hubble constant itself. Right now the plot thickens.

Speaker UNK: Yes.

Speaker B: Because uh first of all, there have been more researchers which have narrowed that number down even more. Remember early uh 2072 plus -8 km/second by now because of additions to the telescope itself. Actually, there were new cameras that were implemented. We've got a new value which is even more accurate. The current accepted value is 73 plus or -1 km/second. So you're down to uh almost a 1% error. And it's actually really interesting because once again, up back to Edinburgh, my boss in those days was the astronomerale for Scotland, Professor Malcolm Longair. Scotsman, actually uh the first Scotsman to be in astronomerale for Scotland. They were always from somewhere else before that. And I remember him saying this would have been in the before the Hubble telescope was launched. We are on the verge of a new era of precision cosmology. In other words, high precision cosmology because it was all hand waving stuff before that. And now we've got 1 km/second accuracy. So good old Malcolm, his words were correct. That's a terrible impersonation of him have to say.

Speaker A: I thought it was pretty good, actually.

Speaker B: Forgive me, a very inspiring person to work with. He was my PhD supervisor.

Speaker A: Actually.

Speaker B: It's terrifying. Anyway, that is a different story. But yes, he was right. We were on the verge of an era of precision cosmology and the Hubble constant tied down to 1 km/second by the work on the Cepheid variables.

Speaker A: But I knew there was a butt.

Speaker B: Coming off Where's the but uh it is the fact that there are other ways of measuring the Hubble constant, and they involve looking at the cosmic microwave background radiation, that sphere of microwave radiation that surrounds us, that we are at the center of. And what we're seeing there is the Echo of the big bang. And when you analyze that, uh which you can do by looking at the slight temperature variations throughout the cosmic microwave background radiation, one part in 100,000 temperature variations, tiny ones. It's been done by a number of different satellites, uh the most recent of which is the European Space Agency's Planck spacecraft, which really sorted out the details and gave us the best analysis of that cosmic microwave background. When they do their sums, they get a different answer. They get a Hubble constant today of 67.5 plus or -0.5 km.

Speaker A: That's a big difference.

Speaker B: It is when you consider what the error bars are. That's uh right. It's a significant difference given those aerobars and that is the current conundrum. That's the problem. And he's engaging cosmologists in a big way. This anomaly, the Hubble constant anomaly. There is one piece of research that is really just being released, uh I think within the last five days, actually. It's in a Press release from the University of New Mexico, and it's about scientists who these are theoreticians, theoretical scientists, University of New Mexico very clever people who build models of the universe is doing, and they have reason to believe it's basically to do with mathematical transformation. So we've got some esoteric stuff from the mathematics that we hope will relate to the reality of what's happening in the big universe. And what they've done is they've uh kind of identified something called a scaling transformation. It's a mathematical entity that's part and parcel of what we're looking at. But uh it turns out that these things are uh symmetrical, these scaling transformations, and they've essentially opened a new path, I guess is the best way to put it, uh to looking at some sort of entity which they're calling a mirror world or a mirror universe that might explain this discrepancy. Now, I haven't, as you can probably tell, Andrew read enough about this yet to get the details. But the idea of mirror worlds is appealing because that's at the heart of supersymmetry, which is the idea from particle physics that there's a whole array of subatomic particles which have supersymmetry with the normal particles that we know about, uh but which we don't see because they're hidden in higher dimensions and things of that sort. So I'm going to crib I'm going to say tech Daily, because they've got a really nice, kind of one paragraph summary of what's happening, which I'll read. If the universe is somehow exploiting this symmetry, researchers are led to an extremely interesting conclusion that there exists a mirror universe very similar to ours, but invisible to us except through its gravitational impact on our world. Such a uh mirror world dark sector would allow for an effective scaling of the uh gravitational free fall States while respecting the precisely measured mean photon density today. Uh and that plays into because the photon density is what comes out of the cosmic um background radiation. One of the scientists who's been involved with this says it's nice to know, to quote them, in practice, this scaling symmetry could only be realized by including a mirror world in the model, a parallel universe with new particles that are all copies of known particles. The mirror world idea first arose in the 1990s, but has not previously been recognized as a potential solution to the Hubble constant problem. This might seem crazy at face value, but such mirror worlds have a large physics literature in a completely different context since they can help solve important problems in particle physics. There you go. Supersymmetry, yes, is what is being referred to. Sorry, just the final sentence. Our work allows us to link for the first time this large literature to an important problem in cosmology. So, yeah, great stuff.

Speaker A: Suppose when you've got a variable between the estimates for the Hubble constant and you can't find a physical answer for it, you have to go to theory, you have to go to modeling.

Speaker B: Yes. So what's wrong with our models? What do we need exactly? Physics works.

Speaker A: Yeah. I also think that this is going to start people asking about dark matter and dark energy. Are they part uh of the equation as well?

Speaker B: Indeed they are, uh because supersymmetry, certainly for dark matter, supersymmetry is one of the great hopes for our understanding of it. Although it's been totally elusive in the particle physics world so far, they haven't cracked it at CERN. They've sort of almost given up on the chase because they don't think they've got high enough energies to detect supersymmetry. But, yeah, I think it's still on the agenda. And what an interesting tie up, though, between the dark matter problem and the Hubble constant problem. Maybe it will all come together in some magical new theory that we'll be celebrating at the end of the year.

Speaker A: Yeah, I was about to suggest that. Definitely worth keeping an eye on.

Speaker B: Thank you. If you want to read the article.

Speaker A: It'S on the Scitech Daily website. So you look for what's the title of the article? Ghostly Unseen mirror World should get you there. This is Space Nuts with Andrew Nutley and Fred Watson.

Speaker C: Space Nuts.

Speaker A: Ok, Fred, let's see if we can answer some questions from the Space Nuts audience. And one of our regulars is Rusty from Western Australia.

Speaker C: Good day, Fred. And Andrew, it's Rusty. And Donnybrook. I have Fred, you're 100 uh percent now after your toe bit adventure. And Andrew, you missed out on uh catching it. So my question is about white holes. Black holes are supposed to be dimensionless. What about white holes? Are they supposed to be dimensionless as well? And if they're not necessarily dimensionless, could uh we be looking at the inside of a white hole when we look at the universe? That's it. Thanks very much for a fantastic show, guys.

Speaker A: Cheers. Thanks, Rusty. Great to hear from you again. Hopeful as well in WA and white holes. Well, first of all, we need to point out that we've never seen one. We don't even know if they exist. But if they did, Fred, would they be dimensionless?

Speaker B: Yes, because what's a white hole? Exactly. As you said, Andrew, they have never been observed, but they are a theoretical possibility that comes out of the equations for singularity, which is what? A black hole is a point in space of infinite density, and it's dimensional. So that's why it's density is infinite. There's no dimensions. So what leads to the idea of potentially a white hole is that if you in the equations for relativity that determine the behavior of a singularity, if you reverse, I think it's time, the parameter time. If you make it negative time instead of positive time, what you get is something that's the opposite of a black hole. You get something from which everything escapes, but nothing can go in. Now, where it's escaping from is a really interesting idea, but, yeah, stuff comes out of it, but nothing can go in. So it's defined as being the same as a black hole. It's a dimensionless point, but it's got this swap of the time direction in the equations. Now, second part of Rusty's question is really interesting, because if you plant yourself in the middle of a universe that's actually a white hole stops leaving, it not sure that you would be able to tell the difference whether you were in the center of a universe made of a giant white hole compared with a giant black hole, because in both cases, you've got this curious gravitational singularity. People have suggested that our universe uh has an event horizon like a black hole does, but in our universe, we're looking at it from the inside rather than the outside. It's my understanding that a white hall would have an event horizon as well. But of course, it will be white, hence the term. And we've never seen one, which leads, I think, most cosmologists to the idea that they probably don't exist, that there'll be some physical reason why this mathematical entity cannot be brought into reality.

Speaker A: I remember a particular Star Trek episode back in the day of the original TV series that Jean Roddenberry wrote, and they go through a black hole and come out the other side, and it was a white universe with black stars. I simply remember that total opposite to the reality that we know. And I uh guess that's what a white hole is technically supposed uh to demonstrate, the absolute opposite to a black hole in every respect. But uh you got to ask yourself, how could it exist rather than does it exist?

Speaker B: Yes, that's right. Just going back to that, though, in a way that's what if your eyes were sensitive to microwave radiation. That's what the universe would look like, a white universe. Yeah. Because you'd be seeing the cosmic microwave background radiation. Pretty Fame, but that's what it would look like.

Speaker A: Jean Roddenberry was pretty darn clever, wasn't he?

Speaker B: Oh, yeah, very much so.

Speaker A: Of course, if you were standing outside our universe and you'd have to run very fast to keep away from it because it would be beige.

Speaker B: It would be beige. That's right. And you'd need to be running at 72 megaparse to keep out the way.

Speaker A: At least.

Speaker B: At least.

Speaker A: Yeah, you'd be right. You've got a bike?

Speaker B: Yeah. Not very well controlled at the moon.

Speaker A: All right. Thanks, Rusty. Good to hear from you. Let's move on to our next question, and it'll be the final one for this episode from Cameron.

Speaker D: Hi, Fred Neander. This is Cameron from Arizona. I had a question about gravity. So you're looking at the gravity field around the moon or planets or anything, and it's not uniform right there's. Gravitational anomalies. Um when you look at things like temperature, though, there's Earth law of thermodynamics says temperature should eventually become equilibrium with each other. Right. You uh put two bodies of different temperatures next to each other, they'll eventually come to the same temperature. Does the mechanism um or a law like that exists for gravity? Should we expect that gravitational anomalies on a planet would eventually even themselves out over time? Thanks. Love the show.

Speaker A: Wow, that's a really deep question. I don't think we've ever been asked or anything similar to it that's way out of left field, but I like it.

Speaker B: Yeah, it's great stuff. Again, I'm um sorry. I'm in nostalgia mode today, obviously, but going back to the Sixties and the Apollo missions, the precursors to the Apollo missions, the fact that these gravitational anomalies were identified on the moon, they were called mass consentrations because you can tell from the orbit of an orbiting spacecraft what the gravitational potential is underneath you. And was because of that, the movement of the spacecraft tracked very accurately that you could work out. There were these mass concentrations. So mass cons was something that we talked about a lot in the Apollo era. They've now been mapped since by the is it the Grail? Grail uh is the pair of spacecraft that were in orbit around the Moon to sense the gravity. Gravity Recovery and Interior Laboratory. That's what the acronym for two spacecraft and the distance between them being measured to a micro or something, and that's how you can track the gravity anomalies. So we do know um about those things exactly uh as described, that objects like the Earth, we've got very strong gravitational anomalies, which are kind of movable feast because a lot of it comes from melting ice in the Arctic and Antarctic. But relating it to the way temperature equilibrium between uh hot and cold objects, there are analogs, actually, and I guess what we're talking about here is a kind of allegorical thing almost because the reason why temperature, if you've got temperature variations in something, the reason why they iron out to become the same is because of one of the heat exchange mechanisms. And for example, it might be if you've got a piece of wood or something like that, which is hot at one end and cold at the other, woods not a very good thermal conductor. So it would take a long time, but eventually the thing would come to equilibrium because of the conduction of heat through the wood happens a lot faster with metal. And we all know about those things. So we know about those various mechanisms for heat transfer. Uh with gravity, though, the gravity is symptomatic of. Well, exactly what we've been talking about, concentrations of mass. So for the gravity to even out, it would have to mean that concentrations of mass evened out. And that would probably happen over very long periods of time. If you've got a world well, think of the Earth with the concentrations of mass underneath. Some of that comes from magma plumes and things of this sort of stuff going on in the Earth's mantle over long periods of time. As that mantle cools, the temperature probably would become even, but it's because of thermal conductivity, again, because of stuff equilibriating, then that uh would remove the mass concentration. So it smoothed out gravity, but it's not gravity itself that's being smoothed out. It's the mass that's causing that that uh is being redistributed, if I can put it that way.

Speaker A: Okay. Right. So the answer is no.

Speaker B: Yes. But it's not gravity. It's the stuff that's causing gravity.

Speaker A: Got you right. I hope that helps. Cameron.

Speaker B: Yeah. Thanks, Cameron. Great question, though.

Speaker A: Oh, fabulous question.

Speaker B: Lovely thinking there.

Speaker A: I saw a really good demonstration. I think it was on TikTok the other day of gravity. I mean, everyone thinks of TikTok, of young people dancing, and that's about it. There's a lot more to it. They have some really great bits and pieces of lectures, and I've started following a few people in the scientific and astronomical world, and they did a great demonstration of gravity the other day. They had a piece of black Lycra stretched out dead flat, and they rolled marbles across it, and they said that's a universe without gravity. Then they put a ball in the middle of it that sunk down, and that was the sun. And then they started rolling the marbles and they spun around it, and they said that's the influence of the Sun's gravity on the planet and the moon, for example. And um they said, now we know you're going to ask a question as to why Earth uh doesn't fall into the sun like the marbles are. And the answer to that question, which I thought was brilliant, was because out there, unlike on here, there is no friction. Therefore, it doesn't spiral into the sun and disappear will one day if it lasts long enough. But I think the sun will probably destroy itself before that happens. I think the timing of the uh function of our solar system won't work to a point where we'll get sucked into the sun, it will come over us instead, I think. Is that right?

Speaker B: Yes, that's right. We are actually moving away from the sun slowly.

Speaker A: It's a really good demonstration, and I suppose you could expand on it by putting different sized objects on the Lycra. So it shows the different influences of gravity, which varies, as we know, due to the massive objects.

Speaker B: Yeah. What's really nice about that, Andrew, is that it absolutely demonstrates one of the fundamental principles of relativity. So, yes, you've got the heavy thing in the middle that's distorting the Lycra, um and the marbles follow curved paths around it. As far as the marbles concerned, though, it thinks it's going in a straight line, but it's the space that it's moving over that's bent. And that's the really neat bit. These geodesix, as they're called, I wish.

Speaker A: I'd known that 40 years ago when I started playing golf, because that's exactly the same effect that I have with puttings.

Speaker B: Yes. Your straight line is a little bit different from what uh the Earth wants to give you, I guess.

Speaker A: Yeah, very true. There's a few other factors in there, like wind and the way the grass grows. You got to take all that into account.

Speaker B: Absolutely.

Speaker A: But that's a different story. But I just thought it was a fascinating demonstration. We really simplified the way gravity acts on things.

Speaker B: Yes.

Speaker A: Now, just a reminder, too. If you want to send us a question or send us a comment or just want to make a political uh statement, you can send it to us via our website,, and you can uh click uh on the AMA link. You can send us text that way or a voice message, or you can click on the right hand side. There's a little tab there, which is vanished off my screen right now.

Speaker B: There it is.

Speaker A: Send us your voice message. So that's how you can ask us questions or just send us voice messages. Some people just send us messages for the sake of it or just want to make a comment about things, which is fine. We use them from time to time. And while they're on the website, check out the Support Space Nuts button and learn about becoming a patron.

Speaker B: There are all sorts of ways of.

Speaker A: Doing that and updating the information um regularly. So if you are keen to support us in a financial sense, you can do that. And there are several options, right down to buying us a cup of coffee, which I love. I'm going to go on that one in a minute. And uh don't forget to put reviews through as well. We really appreciate the people who put in reviews for Space Nuts on their podcast platforms, whichever one you use, because the more reviews, the more attention we get, the more people that join us, the bigger the Space Nuts family gets. And we'd love to have more and more people come across and listen to the show. There's also the Space Nuts shop and all sorts of other information in there if you'd like to check it, or Space Nuts IO. Okay, Fred, thank you so much. That wraps it up for another week. Episode 306, I think it was. Yeah. Numbers are racking up, aren't they suddenly?

Speaker B: Yeah. We could have been on 400 before we know where we are. Oh, yes. Wait for that one.

Speaker A: Wait till we start planning now.

Speaker B: Start planning now. That's right.

Speaker A: Yeah. Thanks, Fred. I'll see you next week.

Speaker B: Sounds great. Thanks, Andrew.

Speaker A: That's Fred Watson, astronomer at large, part of the team here at Space Nuts. And thanks to Hugh in the studio who uh does whatever Hugh does, I don't really know, but we appreciate uh it anyway. And for me, Andrew Duncany, thanks for your company. Hope you can join us on the very next episode of Space Nuts bye bye uh available at Apple Podcasts Google podcasts Spotify iHeartRadio or your favorite podcast player you can also stream on this has been another quality podcast production from - okay that wraps uh it up. Thanks to everyone who watched us live. Thank you. Appreciate it. We'll see you next time, Aroo.