The Dark Matter Hint That Could Rewrite Physics | Space Nuts: Astronomy Insights & Cosmic...

[00:00:00] Hello again. Thanks for joining us on Space Nuts, where we talk astronomy and space science. My name is Andrew Dunkley. Thanks for joining us. We've got a jam-packed program today. Lots of things happening. Casey from Colorado, one of our regular Q&A contributors, put a post on Facebook and I believe sent through an email to us saying, have we found dark matter? Well, according to the Lux Zeppelin scientists, there's a,

[00:00:30] tiny, weeny, small chance we might have. Let's, yeah, I think that's the best way to describe it. There's a wonderful story involving outback astronomy and there's been a new Saturn Decagon discovered. We'll tell you all about that. And a couple of upcoming missions. China is planning a sample return mission to Mars and they've whittled down their 84 potential landing zones to 12 and I think they're going to get it down to less than that perhaps.

[00:01:00] And another similar mission headed for Titan. We'll talk about all of that on this episode of Space Nuts. 15 seconds. Guidance is internal. 10, 9. Ignition sequence start. Space Nuts. 5, 4, 3, 2. 1, 2, 3, 4, 5, 4, 3, 2, 1. Space Nuts. Astronauts report it feels good. And joining us again is Professor Fred Watson, astronomer at large. Hello, Fred.

[00:01:29] Hi, Andrew. How are you doing? I am well. How are you? Still nursing a new knee, but the great thing, of course, always when you've had a replacement knee is that day by day it gets better. Whereas before the operation, day by day it gets worse. Yeah. Well, that makes a lot of sense. You wouldn't want it the other way around. No, you wouldn't. That's right. Well, if it was the other way around, you wouldn't need a knee operation. There you are. Okay. We should get straight into it because we've got a lot of topics to discuss.

[00:02:00] And our first story, I know you've done a bit of radio on this one, but Casey in Colorado sent this one through. And physicists at the Lux Zeppelin detector in the United States think they may have uncovered dark matter. This would be extraordinary if they have. Now, the odds are pretty low, but they haven't said it's definitely not dark matter.

[00:02:30] Would that be a fair assessment? Yeah, that's right. Actually, I'm looking at the wrong script on this at the moment. And in fact, I'm struggling to see anything because I've got a migraine going on here at the moment. Do you get those where you just get this lovely zigzag pattern and cross your face? No, I'm very lucky, but my brother and sister both get those kinds of headaches. Well, there's no headache. There's no headache with it.

[00:02:55] It's just this extraordinary pattern that takes about half an hour to mature. It starts off in the middle of your field of view when you can't see anything, and then it broadens out. And it's something I've observed since, I think the first time I remember it, I was about 16. The first time I remember noticing it. You know what, Fred? I used to have that. There you go. I couldn't explain. I never got it checked out. I just thought it was my eyes doing stupid things.

[00:03:22] But I used to have a zigzag in my vision. And it happened only a few months ago and hasn't happened again since. But it used to be quite regular, and now it's very rare. Well, there you go. Yeah. Wow. It's basically a spasm in a nerve in your brain. And the reason you know it's something going on in your brain is that it's in both eyes. It's not, you know, you can't distinguish between the two.

[00:03:51] I'm so sorry to have diverted our chat. No, no, it's fascinating. Well, you've actually alerted me to something that I didn't even know existed. There you go. It's a headacheless migraine. And it's, yeah, they sometimes come with quite striking colours as well. This one is fairly benign, the one I'm looking at at the moment. Yeah, but it can disrupt what you're trying to do. Yeah, it's not good if you're driving. No, definitely not. Yeah. So, sorry about that.

[00:04:21] No, I'm gobsmacked because I never knew it was a thing. It is a thing. It is a thing. And you had it, you see, and you didn't know. It needs me to tell you what your ailments are. Yeah. But back to dark matter. Maybe migraine to cause by a dark matter interaction. So, as I think probably all our listeners know, because we go on about this stuff interminably,

[00:04:47] the evidence for dark matter primarily has come from the astronomy world because we see evidence that there is material in the universe which we cannot detect. And that evidence ranges from galaxies spinning faster than they ought to if all that's there

[00:05:08] is normal matter, to what we call gravitational microlensing where objects, galaxies, or gravitational lensing rather than microlensing, galaxies in deep space, their dark matter halos act as a lens. And you can see its effect on the stars behind and that lets you plot out where the dark matter lies. And we know dark matter is where normal matter is. So, it's some stuff that is real.

[00:05:34] But the conjecture has always been that if it interacts with normal matter at all, it is extremely rarely. In other words, you know, you need gazillions of collisions between matter and dark matter for one of them to produce a measurable signal.

[00:05:58] And so, that is the basis of some of the detectors that have been built around the world to try and detect dark matter directly. And in fact, there's one here in Australia. It's at a place called Stoyle in Victoria. It's down a gold mine, I think. You bury these things deep in the earth so that you're minimizing terrestrial effects. You minimize anything that could be happening near the surface.

[00:06:27] And what you do is you typically, and the one that we're, I should just go straight to the one that we're talking about. It's an experiment at the Sanford Underground Research Facility in South Dakota. And that is an experiment called Lux Zeppelin, usually abbreviated to LZ, I guess it would be rather than LZ.

[00:06:53] That is an experiment that, if I remember rightly, I don't have my notes in front of me on this. It's got something like about, I think it's 10 tons of liquid xenon. Something that's gaseous at normal temperature and pressure, but is liquefied. So 10 tons of this stuff deep underground. And what you do is you have a tank which is festooned with photodetectors.

[00:07:21] So if anything flashed in the tank of xenon, you could identify it. And more especially, because you've got lots of detectors, you could track a particle if that's, you know, the way it goes, because you've got multiple detectors, which are all active all the time. Hmm. So that is where it's got to in terms of the experiment.

[00:07:50] But what's happened is they've detected a flash. Yeah. Which is a result, I think it was announced only a few days ago, 1st of September. The, in many ways, it's the first hint, certainly the first hint that's come from the USA, that maybe one of these collisions has been observed. Now, I'm not a particle physicist, Andrew.

[00:08:19] As you know, I'm supposed to be an astronomer. Probably am, actually, in some ways. And the, so I'm not sure of the exact nature of the observation, whether they observe this flash in different wavelengths, in other words, using different filters, and can analyse what the spectrum of that flash looks like, or whether it's something more subtle than that.

[00:08:45] But that is what is currently going on now. And I think the surprise is that this thing has a relatively low energy. It's a slow particle. And they're talking about energies of, I think it's in the region of 250 kilo electron volts, keV, 248 keV of energy in the detector.

[00:09:12] Now, the Large Hadron Collider collides particles up to terravolt energies. So, a kilo volt and a terra volt are very wide apart. But that's an interesting aspect of this. So, I think it's one of these stories that will evolve. I mentioned a minute ago that this was the first time it's been detected, or there's any kind of detection, in the US.

[00:09:42] And that's because there's an experiment at a facility called Grand Sasso National Laboratories, which is in Italy. And there's one in China, too, which I think these, certainly the Italian one has picked up things before. And there's evidence from the Italian operators that they thought they'd found a, and I think we talked about this on Space Notes,

[00:10:10] they thought they'd found a seasonal variation in the flux of what might be dark matter. But that's not been replicated anywhere else. I think that was one of the reasons why the Stahl facility was initiated down in Victoria, in order to check whether this is real, the story that's coming from Italy. Unfortunately, I can't read any more in my article because it's got these zigzags across the field of view,

[00:10:38] which are interesting in their own right. But I think that's the bottom line there. Yeah, I think they're saying, look, it could be. The odds of it being a dark matter discovery are 0.5%, I think they're quoting. Yes, that's right. Isn't that the odds that it's not real? I can't remember which way. Oh, is that what they're saying? I might have read it backwards. Just look at that again. Yeah, I'm trying to find it now.

[00:11:07] You know, we think in terms of sigma, the number of standard deviations, this doesn't, I think five sigma is the normal acceptance for a fact. I don't think it's anywhere near that. But it's still, I think it's still got quite a high level of probability attached to it. And just to clarify, I'm sorry, what I said was just a bit misleading. That 248 kilo electron volts is actually a recoil.

[00:11:36] That's a recoil of a particle. And so they can deduce from that that it would be at least 200 giga electron volts that your dark matter particle would have to work out. That's quite interesting. I found it. The team reached what is known as 2.6 sigma, a 0.5% chance that the event could be explained by known backgrounds.

[00:12:02] And that is still below a five sigma threshold needed to confirm a discovery. So there you go. A bit more complicated than what I thought. Yeah, but it's intriguing. It's, you know, this could just be the first chink in new physics that we've been looking for that might give us an explanation for what dark matter is. Indeed. They've published their findings in the archive.

[00:12:29] It is yet to be peer reviewed, but I'm sure it will be. It'll be reviewed to death, you can believe. Yes, absolutely. Yeah. You can also read about it on the ABC Science website. Yes. This is Space Nuts. Andrew Dunkley here with Professor Fred Watson. Swiston Tranquility Base here. The Eagle has landed. Space Nuts.

[00:12:55] This story, Fred, I love because it involves an outback astronomer. It is a new decagon that's been discovered on Saturn around its South Pole. And Trevor Barry has made the news at a broken hill in outback New South Wales because he was a part of this find. Absolutely. Trevor's an old friend. Trevor and I go back to the mid-1990s when he first visited me at Siding Spring Observatory

[00:13:22] and we hit it off and we've been in touch ever since. He, let's just do the Trevor bit of the story because this is certainly, you know, a double barrelled story here. He discovered astronomy when he was a, he wasn't a miner, he was a mine worker in the, I think he was a fitter actually in the mines in Broken Hill. And one of his colleagues built a telescope and Trevor had a look through it and the planet

[00:13:51] Saturn and has been hooked ever since. Yeah. And built a succession of telescopes, which are impressive. I've seen the one that he uses currently. It's a 400 millimeter telescope, homemade. Some of its components came from an old washing machine. It's great stuff. It's kind of, you know, the absolute essence in a way of good amateur astronomy. But with that telescope, he observed Saturn. I think actually it's not just Saturn. He checks out other giant planets as well.

[00:14:20] But Saturn is certainly his area of speciality. And he checks it out every clear night. And that was why he got co-opted onto the Cassini team back in the early 2000s with Caroline Polko, the image scientist of Cassini. Trevor was the one that said, there's a storm in, you know, Saturn's Northern Hemisphere. You might want to take a look at it with Cassini.

[00:14:48] Because, of course, the Cassini spacecraft didn't have the global view of Saturn. It just had its instruments that could be pointed in any direction. Whereas Trevor, with his telescope, could see where the activity was. And he was their guide. So, of course, he received lots of honors from that. I know he has spent a lot of time studying the North Polar Hexagon of Saturn.

[00:15:13] And that's a feature that was discovered, actually, by the Voyager spacecraft back in the 1980s, but was analyzed deeply by the Cassini mission. So, this is a jet stream. It is a very, very regular hexagon. It almost looks as though there should be a spanner somewhere nearby because it's that shape. Yeah.

[00:15:39] And it's formed by, it's basically a six-peaked wave that's formed in a circle. But it looks like a hexagon. You wouldn't be able to take a spanner to it because each side of the hexagon is 2,000 kilometers bigger than the diameter of the Earth. So, this is large. Now, Trevor has studied the hexagon in great detail. But, of course, one of the, and he's got papers with his colleagues from NASA and elsewhere with that.

[00:16:05] One of the things that has puzzled astronomers is why isn't there one in the South Pole? Why isn't there a hexagon or something like it near the Southern Polar region? And so, that is something Trevor has long kept an eye on working with his colleagues, one of whom is actually in Spain. In fact, we were very close to where his colleague Augustine works.

[00:16:31] We were very close to where it is about a month ago when we were there for the eclipse. The bottom line is that within the last three years, they've started seeing evidence of something fishy going on, which has now been followed up by the Hubble telescope. And what has been revealed is not a hexagon, but a decagon, a ten-sided figure around the South Pole of Saturn.

[00:17:00] And the big difference between that and the hexagon, we don't know how old the hexagon is. We don't know how long it's been there. But we do know that this decagon has only been there since 2023. It's probably still in the process of formation. And so, this is the result of the announcement that's been made in this paper within the last couple of weeks in Science Advances. Trevor is absolutely over the moon. He sent me an email when the paper was released.

[00:17:30] You could tell it was bursting with delight as to what's happened. He's had, as always, when Trevor makes a discovery, because he's the astronomer of Broken Hill, he gets a lot of media coverage and quite rightly too. This year saw the publication of a book on his life, Outback Astronomer, which is a very nice book. I was privileged to write the foreword for it. So, it's one to look out for if you're interested in following Trevor's career.

[00:17:55] More especially, though, if you're interested in following the decagon, there's really good news. And that is that, at the moment, Saturn, where it is in its orbit, it's moving towards the southern summer solstice, which means that the south polar region of Saturn is tilted towards the inner solar system. In other words, towards us.

[00:18:22] And so, the solstice is, I think it's April 2032. So, between now and then, we'll get better and better views of this decagon, assuming it lasts. I mean, it could be something that is so temporary, it just collapses. But it's definitely there. It's easy to find pictures of it for our listeners who might want to chase it up on the web. It's a great discovery with a lovely backstory as well concerning somebody who's, I think, very special in the world of astronomy.

[00:18:52] Even right down to his corrugated iron-clad observatory. Yeah, that's right. Absolutely. It's got all the bells and whistles. I think I remember, I need to check it in Outback Astronomer. One of his telescopes is called FRED. And he's made it into an acronym, but he's done me the honour of naming his telescope after me. Isn't that nice? Yeah. Yeah.

[00:19:18] There's a fabulous story on the ABC about him. If you want to look it up, it should be easy to find. Just do a search for Trevor Barry, ABC, and it'll pop up. You can read the published paper in the journal Science Advances. But, yeah, great story, great local connection, and congratulations to Trevor and everybody involved.

[00:19:43] And I've got to say thank you to Casey for sending us that first story about Lux Zeppelin. This is Space Nuts, the podcast and the radio show on community radio across Australia with Andrew Dunkley and Fred Watson. Zero G and I feel fine. Space Nuts. Now, we've got a double bunger story here because they're of a similar ilk in very different parts of the solar system.

[00:20:10] And the first part of this story involves China. And they're getting right down to the nuts and bolts. Nothing to do with Saturn's South Pole. But right down to the nuts and bolts of finding somewhere to land on Mars for a sample return mission looking for ancient life. This is very exciting. It is.

[00:20:35] And I think this is going to – I think it's something that's going to not go unnoticed in the halls of NASA. Because, of course, NASA has Perseverance on the surface of Mars at the moment, which has gathered up all these samples of soil and dirt from the surface of Mars.

[00:20:56] It's more than 20 samples, I think, they've got now, which have been left in little containers with the idea of picking them up to bring them back to Earth for analysis on our planet. But at the moment, there's no mission planned to do that. No, they've just left them lying around like a dog would do. Yeah, exactly. Whereas China, they're planning a mission that will actually do it all, basically.

[00:21:25] It'll have a lander on the surface with a rover, which will scout around. I've got a feeling there's a drone involved as well. So it's going to check out good sites. It'll drill. And I think the drill goes – the idea is to go down up to two meters, which is actually what ESA's ExoMars rover is planning to do.

[00:21:52] Grab samples and then send them back to Earth more or less immediately. And so this is – if that happens before we get the Perseverance samples back, I think a lot of people are going to be miffed about that. What would be even more spectacular would be if there were signs of past life among the Tianwen-3 Mars sample returns. So it's an exciting project.

[00:22:21] I think 2028 is when the launch is going to take place. Two spacecraft will actually be launched. There'll be two launch vehicles. One, I think, for the lander and rover, one for the orbiter and the return spacecraft. So, as you said, quite right, they had 86 candidate sites originally. They've narrowed it down to a dozen. Is that right? I think it was 12, yeah. Yeah, yeah.

[00:22:50] And they're all in, I think, a similar part of Mars' equatorial region. Places where we know that there are clays. And, of course, clays are minerals that were formed in water. And they are good at preserving organic molecules and maybe give us more of a chance of finding evidence of past life there, you know, DNA evidence or something of that sort. Yeah. So this is exciting news.

[00:23:19] And I think it's, you know, it's hats off to the China National Space Administration for the plans that they're carrying out. Yes, indeed. It's the Tianwen-3 mission because they've already done it twice in the past, landing things on Mars. But I do believe there is a copter involved. I can see that in the story there. I just can't find any reference to it.

[00:23:48] But I think they've got a, yeah, it looks like it does ground tracking from the sky. Yes, a little drone. Yeah. Now we know drones work on Mars. They do. Yeah. Fantastic. And they will be launching this probably in 2028. Is that right? Like 2028. Yes. Two separate long March 5 rockets.

[00:24:14] And so we may have answers in the not too distant future, all things being equal, which is fantastic. We wish them well with the mission. There is a similar mission, speaking of NASA, which is headed to Titan. They're looking at a 2028 launch as well. And they're off to Titan and they should get there in 2034 if they don't forget to pay their tolls along the way.

[00:24:43] This mission is the Dragonfly mission. I think we have mentioned it before. We have, yes. It's getting ever closer. And they're really getting to the pointy end by the sound of it. That's right. So, and the announcement is very similar. We've, you know, coming from the Dragonfly team, they've basically decided where they are going to land on Titan.

[00:25:08] It is an area called Amakikunde, which is a region of dunes. And dunes are, these are probably dunes of ice, actually, ice particles rather than sand. But there's a crater called the Selk Crater, which this dune region is to the south of.

[00:25:34] They think it is a really interesting geologically productive region. And the idea is to give the drone, you know, as much of a variety of landscape as possible to check out. This is the Dragonfly drone. I think it's an octocopter, if I remember rightly.

[00:26:00] So, I think there's a sort of range of hills or mountains at the edge of this region. And so, that's the plan, to go there with a 3.3-year primary mission. And as I'm reading a little blog post here about what is going to be done with Dragonfly comes from Len and David.

[00:26:24] It's once Dragonfly reaches Titan, the Rotocraft will conduct a 3.3-year primary mission, exploring diverse environments from organic dunes to deposits associated with Selk Crater, a place where liquid water and complex organic materials key to life once existed together. Remembering, of course, that the surface of Titan is at about minus 190 degrees Celsius. How is something made on Earth, like the Dragonfly spacecraft,

[00:26:54] and more particularly the equipment they're going to put down at Selk Crater or that area, are going to survive that long in such a hostile environment? It's not a nice place. No, not really, no. It's got quite high atmospheric pressure, so that'll make the drone easier to fly. That was one of the challenges with Mars, of course, flying the helicopter on Mars was the fact that Mars has atmospheric pressure less than 1% of the Earth.

[00:27:23] So ingenuity, the helicopter had to have big wings. Perhaps the drone, the Dragonfly drone, won't need quite as much. Really interesting project, though, and one that we will continue to watch with interest, Andrew. We will, yeah. And both those missions coming up very, very soon. So we're, yeah, only a few years away from getting maybe potential answers

[00:27:48] to some of those great questions that we've been asking for decades and decades. Yes, indeed. You can read that story on the website leonarddavid.com. Before we finish up, Fred, I just wanted to sort of do some shouting out. We've got a listener that refers to him or herself as the Web Pro in Chile, listening to us or watching us on YouTube live today. And hello to Emily.

[00:28:17] This is, she says, watching us is cool. I think it's very cool. She's listening from an offshore oil rig, oil and gas rig in the Indian Ocean off the coast of Western Australia. So hi, Emily. We were on a ship crossing that area a bit over a year ago. So, yeah, it's lovely to have you listening along and everybody who's watching, actually, on our YouTube channel. We are done, Fred.

[00:28:45] Thank you so much. It's a pleasure. Always good. And thanks, Andrew, for putting up with my discussions about migrates. Oh, no, I'm glad you brought it up because I actually learned something. I'm delighted to tell you it's now cleared completely. It does that. That's exactly how I remember them. They just sort of go away. It's weird. All right. See you soon, Fred. Thank you. Professor Fred Watson, astronomer at large. Don't forget to visit us online at our website,

[00:29:15] spacenutspodcast.com or spacenuts.io. Have a look around while you're there. Maybe leave some reviews wherever you listen to us. Reviews are very helpful to get our numbers up. I don't know what the numbers are for or what they do, but it's pretty important, apparently, according to Hugh. And thanks to Hugh in the studio who couldn't be with us today because he did a sample return and they put him in hospital. And from me, Andrew Dunkley, thanks for your company. We'll see you on the next episode of Space Nuts.

[00:29:45] Bye-bye. Bye-bye.