From Dark Matter to Planetary Nebulae: Delving into the Complexities of the Universe | #375

[00:00:00] Hello once again, thanks for joining us. This is Space Nuts. My name is Andrew Dunkley, great to have your company and in episode 375 we will dedicate the entire show to audience questions, and we've got a bunch

[00:00:15] We're going to be looking at the Big Bang and the gravity associated with that We'll also be looking into What the universe might be like if there was no such thing as dark matter. I love the what-if questions and a

[00:00:32] Carbon star called La Superba. Somebody's asking a question about that. We've got a whole bunch of questions We better get into it right now on Space Nuts And Joining me again to discuss all of that and so much more is Fred Watson, astronomer at large. Hello Fred

[00:01:06] Hello Andrew. How are you today? I'm very well, sir, feeling relaxed. Judy and I did a four-night cruise out of Sydney last week Just up to Moreton Island and back Unfortunately, the weather was not kind to us. So we never got off the ship

[00:01:20] So, but you know, that's okay there's always plenty to do on a ship and We had a lot of fun was was nice to just have a bit of a breather and just not have to worry about anything

[00:01:31] No bed making no cooking. No, just get up. Hey go to sleep. That was pretty well the baton And check out and check out watches as well, of course watch it go to the watch shop. Yes, I've

[00:01:44] That's become a regular thing when I go on a cruise ship I don't know why because they cost ten times more than if I go into a jewelry shop But I just I've just become fixated with watches and I think it's because my grandfather was a watchmaker and

[00:02:02] When I was growing up I used to go to his shop and watch him out in his little workshop at the back fixing watches in the days where you actually did fix them and

[00:02:11] I was just fascinated by it. Just thought it was amazing because during World War two he was an instrument fitter for the RAAF and So he was out around the New Guinea Islands where the Japanese were occupying

[00:02:24] so it pretty tense times came back and got an apprenticeship as a watchmaker and yeah, I Even visited the first shop he worked for in Griffith when we were down there. Oh Yeah. Yeah, he sailed through Watchmaking with that instrument fitting background. Oh, yes Certainly those days the

[00:02:46] Mechanics were much the same. All watches is for aircraft instruments. That's why this watch I've got is fully mechanical No batteries, no winding it up Automatic it just winds itself. I've always been fascinated by that Yeah, it's good gear. I am I just as an aside So

[00:03:07] during the late 50s and early 60s in the United Kingdom There were these wonderful government surplus shops and there was one in particular that I used to hang out in and I used to regularly buy lots of optical instruments, which is how I

[00:03:22] You know got hooked on on the way lenses work and things like that And it was all about trying to make telescopes for astronomy, but they also sold aircraft instruments You know surplus aircraft instruments and pulling one of those two bits was a lesson in watchmaking

[00:03:38] But yeah, it was the same sort of stuff inside. It was remarkable Yeah It's so intricate too because he used to sit there with his little Thing attached to his glasses so he could magnify wasn't what makers I glossed. Yes, exactly. Yeah

[00:03:53] Alright we better get stuck into whatever we're doing today for it and That in that involves 40 minutes. Well, we could just keep Talking about what I think we could just get involved the audience as well. They want to know about what's making

[00:04:08] Let's go to our first question. This comes from a familiar voice. His name is rusty Hello, Fred and Andrew. It's rusty and Donnie brook. Now. We know it's common usage now that common knowledge that gravity affects

[00:04:24] The passage of time and we have to make adjustments for it with our satellite navigation So taking that a step further black holes as we're closer to black holes Yeah recent movie Highlighted that time slows down

[00:04:42] But the event horizon there's no physical reason why at the event horizon time wouldn't slow down further as you approach the singularity and Finally when you get to the singularity of a point of infinite density Time would stop all together, wouldn't it? so

[00:05:00] One more step we go to the Big Bang Before it expanded into the universe. We know it was very tiny and all of the matter Was squeezed into a very tiny little pinhead point So wouldn't gravity had slowed time down

[00:05:20] To an incredible degree and what we measure now is milliseconds or silly seconds Would have perhaps taken very much longer as we would would measure it now today and so the could

[00:05:37] The infant universe the embryonic universe have taken trillions of years to break out of its pinhead size. That's the question Cheers guys Thanks rusty. You got there eventually So yeah, could the early universe have taken? Trillions of years to break out of its infinitesimal Minisculeness

[00:06:02] If that's a word and The answer is yes If you could have observed the universe from the outside because it's all about reference frames that the thing it's why time You know to an outside observer time appears to slow down for somebody falling into a black hole

[00:06:20] And in fact is when you cross the X the events arise and that time appears to stop altogether Excuse me. I've got a time dilated frog in my throat and so the the bottom line is it's about reference frames, but I

[00:06:36] Think rust is his point is kind of well made because the same thoughts has occurred to me that you know We talked about the period of inflation now

[00:06:45] I'm gonna get these numbers wrong, but it's something like it started when the universe was 10 to the minus 33 of a second old When stopped when it was another 10 to the minus 33 of a second old and those are just ridiculous

[00:07:01] Ridiculous time scales, but if you were in the privileged position, and I think there's only God can do this But if you were looking from the outside at the universe Then yeah, it might look like trillions of years. That's right

[00:07:17] But for those of us involved directly with the Big Bang which is everybody in the universe It was a Very short, you know it might have looked like a long time to somebody outside

[00:07:31] There's a very short time in the in the in the time dilated rest frame. That's the way to be precise about that There is some, we talked about it recently Andrew Some work that's been done here in Australia

[00:07:46] Which involves looking at distant quasars and there's a sort of clock signal that you get from those and these astronomers showed that yes We are looking from the outside effectively at the time regime that those quasars were in and there is time dilation

[00:08:03] Quasars were in and there is time dilation taking place You can demonstrate that that what we see looks slower than what it actually was because of gravitational time dilation It's just so hard to get around You're looking puzzled there, yeah, I don't blame you

[00:08:20] Just the idea that the universe existed for trillions of years on a minute scale before the Big Bang I mean That well, that's another possibility you can't prove it but Yeah, it's just that's just a massive time scale to try and absorb and to try and you know

[00:08:43] To try and figure I mean when we've talked in the past about what was there before the Big Bang The answer is nothing. So there were trillions of years of yeah, and then there was something

[00:08:52] No, no, no, there wasn't trillions of years of it because time didn't exist either. So there was nothing Not even time not even time. I don't know see I My brain doesn't like this

[00:09:07] No, I don't think anybody's brain does actually I think you know, that's in that regard watchmaking is a lot more straightforward than Relativistic cosmology. Yes, because none of it is intuitive You've you've really got to go into the mathematics and sort it out that way

[00:09:24] But the big question is if I did get sucked into a black hole and cross that threshold when time stopped Would my watch keep working? It would your watch wouldn't know any difference about being spaghettified that might interfere with the works

[00:09:39] Let's just pretend that it's certainly my goodness for the self-winding mechanism Indeed, all right. Have we given enough attention to rusty's question think we covered it Yeah, I always try to go on and say hang on this one this thing

[00:09:59] Yeah, no in as much as we ever cover anything Andrew I think yeah, we've covered that all right, thanks rusty Let's move on to our next question. This one comes from Michael. This is pretty deep thought question as well Hey guys

[00:10:16] This is my colleague from Toronto, Canada. I just have another question for you guys. I I've been thinking we usually hear about Einstein's e equals MC squared as sort of a conversion From mass into energy. So I understand that it's probably a bi-directional

[00:10:41] Kind of conversion that could happen, but I don't usually hear much about Energy being reconverted into mass Are there any situations that you're aware of where this does come up So I was thinking

[00:10:59] Maybe this could explain dark energy or dark matter say maybe there are some kinds of energy like Gravitational energy or maybe even the energy that's produced from photons in fusion and in stars. That's really that's Somehow responsible for what we

[00:11:17] Perceive as dark energy or dark matter. What do you think? Thanks guys Thank You Michael Yeah, like I said a pretty deep thought type of question basically Yeah turning energy into mass any evidence of that and

[00:11:36] You know, how would it work in a universal state well the situation the Probably the most well-known example of energy being turned into mass is the Big Bang. Yeah, because that's not was you know, it's just energy I

[00:11:57] Guess photons and eventually became well, yeah, it became became a kind of super particles. In fact the the first set of Yeah, this is laws of physics which is slightly different the There was a one of the first things that happened was the break between the

[00:12:18] Electroweak force which is what holds Nuclear atoms together and the electromagnetic force which is photons that sort of happened in the early Big Bang period but that's that's more Sort of separation of forces rather than energy being turned into mass, but energy did get turned into mass

[00:12:37] That's kind of how it worked But if you check up Online, it's a it's a rare phenomenon But there are examples. I think we've actually talked about them before Andrew. It's quite a long time ago, but The back in 2021 the Brookhaven National Laboratory in the USA

[00:13:02] Basically they issued a press release entitled collisions of light produced by collisions of light to produce matter antimatter from pure energy and so And this is an article that you can read it goes into details about particle collisions in the relativistic heavy iron collider the RHIC

[00:13:24] Which is a US Department of Energy Office of Science user facility for nuclear physics and it's a Brookhaven the DOE's Brookhaven National Laboratory, so what they've done is Basically Collided

[00:13:43] Essentially beams of light I might actually read the beginning because that explains it a lot better than I can They've produced definitive evidence for two physics phenomena predicted more than 80 years ago The results were derived from a detailed analysis of more than 6,000 pairs of electrons and positrons

[00:13:59] produced in glancing particle collisions at the RHIC and are published in physical review letters The primary finding is that pairs of electrons and positives in other words Sorry pairs of electrons and positrons in other words particles of matter and antimatter Can be created directly by colliding very energetic

[00:14:22] photons which are quantum packets of light this conversion of energetic light into matter is a direct consequence of Einstein's famous equals MC squared equation which states that energy and matter or mass are interchangeable Nuclear

[00:14:36] Reactions in the Sun and at nuclear power plants regularly convert matter into energy now Scientists have converted light energy directly into matter in a single step And so you can you can read more about that

[00:14:48] But that what that tells you Andrew and and Michael indeed is that we're talking about something. That's not commonplace phenomenon in the natural world Where we're seeing the other process happening all the time in the Sun

[00:15:04] Matter being converted into energy, but to convert energy to matter is a rarity But it can be done as we've just heard. All right, Michael. So the answer was yes Could have saved a lot of time if we just said that but good. Yes

[00:15:21] very good question, very very good question and and his How would that relate to his question about black holes and dark matter dark energy Any relationship there? Yeah, sorry. I should have followed up on that well, the thing is that

[00:15:42] You know dark energy our understanding of dark energy and dark matter That they take into account this rarity of such Kind of reverse engineering taking place of creating mass from from any purely from energy and I think I

[00:16:02] Suspect it's not something that has been overlooked by the cosmologists involved the possibility but I think it's such a difficult thing to achieve that You know, it might it might be it might be something that is

[00:16:20] Essentially ruled out by the theory and what I was going to say was we kind of What we don't know about dark matter and dark energy is what they are We can kind of guess where they came from because the Big Bang lets you

[00:16:37] Look at the kind of energy budgets that are there and you basically get what we see around us today If you do the mathematics universe, that's kind of three-quarters dark energy about 20% dark matter and 5% everything else. Yeah, so

[00:16:55] It's more about the puzzle with dark matter and dark energy is how that you know what they are What what particles carry dark matter? What some atomic particles as well because you can look at it that way would carry dark energy and we don't know the answer to

[00:17:09] that Mmm, okay can sort of work out where they came from if that's a paradox that you could deal with All right, thank you Michael yes and maybe probably not don't know I think with the answers Question Yeah, it's pretty much

[00:17:29] Lovely to hear from you Michael. Hope all is well in Toronto Peter has emailed us a question Peter is from Sydney and a proud patron So thank you very much Peter appreciate your support

[00:17:43] Of Space Nuts as a patron. He says money well spent look it's there in writing I'm surprised but delighted Now he asks I'm placing his question because it quite long

[00:17:57] What if the universe evolved from the Big Bang without any dark matter apart from probably halving the number of questions from listeners? What other effects would there be Could galaxies still form but maybe rotating at a lower velocity so they don't fling apart

[00:18:14] Would they still have spiral arms and all the other shapes and sizes they come in would solar systems form in a different way? Would we still have galaxy clusters? And what about black holes surely dark matter is not the only mechanism in the universe

[00:18:31] That has to coalesce hydrogen Or am I wrong? If the above is no I can only assume that the universe would just be an ever-expanding soup of hydrogen and helium atoms looking forward to your answer Toddy, thanks, Todd

[00:18:51] Yeah, I love what if questions what if there was no dark matter or dark energy or any of that stuff? I thought that was from Peter not Toby Peter. Well, he calls himself Toddy, but Peter Todd is he's not

[00:19:07] Peter Todd's right now you see me. Yeah, that's great Nice to hear from you Toddy. I always have quite different Pictures in my mind when I think of a Toddy, it's a mixture of water and whiskey

[00:19:22] That is got honey in it and it's what gets you through a bad cold Especially if your whiskey is something nice and peaty like Lagavulin. Anyway moving on to other things so it's a great question because

[00:19:40] that's exactly the issue that the proponents of MOND have to deal with and MOND Is which we've talked about many times is this alternative theory that gets rid of the idea of dark matter modified Newtonian dynamics Mordehai Milgram's

[00:20:00] Contribution to the world of physics back in the 1980s when dark matter was first being recognized as a reality he didn't like the idea and looked at the idea that perhaps our understanding of dynamics was wrong the way

[00:20:15] you know accelerations take place at very very low levels of acceleration and he developed this theory of MOND modified Newtonian dynamics Which has merit as we know because we've got friends on

[00:20:29] on Space Nuts notably Peter Verweyen whose PhD thesis is on exactly this topic and Peter talks to us from time to time so so MOND has certainly has some

[00:20:42] Useful attributes, but I think one of the things now Peter might well be able to correct me on this and I'm talking about Peter Verweyen now not Peter Todd But I think it struggles to make galaxies in the early universe because of exactly what Toddy has

[00:20:59] mentioned the fact that we think the dark matter provided a framework that basically attracted gravitationally attracted the hydrogen and made you know Made stars and galaxies by acting as a kind of nucleus for for gravitational attraction But yes

[00:21:16] It will be possible to imagine the universe that never formed Stars and galaxies and it would indeed be made mostly of hydrogen and helium with not much going on So I think that's I think that is still an issue for MOND

[00:21:31] But we might hear from Peter that there are answers to that But you know, it's a great question and like all or like so many of the questions we get from Space Nuts listeners It's right at the cutting edge of research that

[00:21:45] Toddy's asking questions that we we really probably don't properly know the answers to no No, it doesn't stop people wondering and it's the fact that we wonder that leads us to investigate that leads to Ultimately answers in some cases

[00:22:02] Be fair yes, we hope that yeah, we honey we hope yes Yeah, or it just brings up more questions, which is quite common too. Well, that's the other thing that happens as well

[00:22:14] That's right. Yeah. All right. Thanks Peter or Toddy as you seem to like to be called. I appreciate your question Thanks for sending it in. This is Space Nuts Andrew Dunkley here with Professor Fred Watson

[00:22:27] Let's take a little break from the show to tell you about our sponsor Nord VPN and I'm pleased to be able to tell you that Nord has got a New offer available to you as a Space Nuts listener now, I might add that you get

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[00:25:14] That's Nord VPN comm slash space nuts now back to the show Space nuts. Okay Fred. Let's Go to another audio question This one I was particularly interested in because I think we talked about this not so long ago. This one comes from Doug

[00:25:36] Hello, dr. Watson and mr. Dunkley This is Doug stone back from Boise, Idaho And I was just wondering We were looking at a carbon star called la superba it's a red giant and Just wondering if Or one this turns into a planetary nebula Would it show?

[00:26:04] the same color because of its richness in carbon and the atmosphere Are there any? planetary nebulae that came from carbon stars and Thirdly in regards to the blue snowball a blinking planetary and the cat's eye nebula Of course, they're all a bluish and turquoise type of color

[00:26:32] Is that due to their atmospheric? Makeup Could it possibly be methane as in Neptune and Uranus I'd love to Know the answers to these questions so I can pass this along to the public Thank you And have a great day and keep up the fabulous work

[00:26:57] Thank You Doug Last super but I suppose we should start by explaining a bit about it and what a carbon star is and then we can sort of move into the the spectrums Yeah Indeed, so it's a star. I'm interested to know actually whether Doug has observed it

[00:27:18] because it's It's let's see. I think it's Yeah, it's fifth magnitude. It's a star that's visible to the naked eye not particularly so from our latitude here in the southern hemisphere because It's declination is 45 degrees north, which means that it's a northern hemisphere

[00:27:40] star it's in the constellation of Canis Venatici And in fact, it is why can am Venati Chorum? There you go The hunting dogs Canis, Vetinici And that's a northern constellation. It does Cross our northern horizon here in Australia, but not for long

[00:28:07] And so it's not one that would be well known and in fact at that zenith distance. In other words that low in the sky from from here a fifth magnitude star is probably not going to be that visible to the naked eye and

[00:28:20] Especially if you're anywhere near city lights but Yeah, so but it's called La Superba And it was named by an Italian astronomer in the 19th century whose name was Angelo Secchi or Secchi

[00:28:39] He called it La Superba because of its beauty and its beauty comes from the fact that it's a very red star In fact, it's one of the reddest stars known and it is Exactly as Doug has mentioned. It's a carbon star

[00:28:55] And carbon stars have a richness of carbon in their atmosphere So this is a star that's It's slightly bigger than the Sun in terms of its mass, but it's turned it evolved into a red giant and in fact one of the estimates of its diameter is

[00:29:17] Effectively bigger than the orbit of the earth. So around the Sun So, yeah, it's big and so what you get is Basically You get a core of carbon and oxygen And Within the star. This is kind of the old age of stars similar mass to the Sun but

[00:29:48] Similar mass to the Sun but the hydrogen and helium burning Continues, but it's in shells sort of outside the core and basically Though this convection takes place that dredges up the carbon from the core

[00:30:09] Because carbon and oxygen in the core the carbons dredged up into the outer atmosphere And it forms carbon monoxide and other carbon compounds and basically you get absorption of the light from the still burning hydrogen In short wavelengths. In other words, it turns red and that's so

[00:30:31] It's a red giant star at a particular phase in its in its evolution It's already got a shell Of stuff that it's ejected And You can sort of detect that because of once again of the spectrum, but eventually That will turn into

[00:30:56] Exactly as Doug says a planetary nebula now i'm not sufficiently familiar with the details of planetary nebulae to understand Or at least to keep carrying my head where the Where the different elements come from that are in planetary nebulae, they clearly come from the star itself

[00:31:17] Through the nuclear processes that have taken place while the star was in its normal life But what's happened with a planetary nebula is that basically a star has Cast off its outer layers and the core itself has turned into a white dwarf star. It's a

[00:31:32] a white dwarf which is highly energetic collapsed core of a star Which is pretty bright and very very hot hence its color And will last a long time before it eventually turns into a black dwarf

[00:31:46] Which is what most of the stars that we see around us are going to do in the distant universe. But So Doug's comments about The materials in the in the Tendrils of these planetary nebulae which are

[00:32:06] Only called that because some of them look like planets. They're not they're just shells of gas often with quite complex morphologies, they've got very Troubled looking appearance. I can't comment on the details of that

[00:32:20] But I could you know, i'll try and try and put some detail on that for the future But Doug could be right about for example methane being in there because these things are cool enough

[00:32:29] The molecules can form that the hotness is the white dwarf at the center, but it's cooler in the edges So there's probably molecules which which can only form in relatively cool conditions I'll check that because it's an interesting question. What Elements and molecules you get in planetary nebulae

[00:32:47] Okay All right, Doug. We'll leave it there, but there'll be more to come but yeah thought-provoking question And thanks for sending it into us. We'll move on to a text question now from Dylan. He said hi there

[00:32:59] I have a fun what-if scenario for you to think about imagine a world where every space agency Had an unlimited budget and zero bureaucratic hurdles Starting from the 1950s or even earlier in such a scenario. How advanced do you envision?

[00:33:16] Not only space technology, but all technologies to be today could NASA have established a presence on mars in say the 1990s maybe asteroid mining in the early 2000s This concept resonates with the tv series for all mankind where the space race continues

[00:33:34] At full throttle and technology is pushed and milestones are achieved that have Not been seen today in real life. I'd be interested in what you both think cheers Dylan I love what-if questions. So we've got a situation fred where there is no limit

[00:33:51] They can spend as much as they like they like there are no bureaucrats Or politicians to slow them down. What would the world be like today in terms of space exploration and development? Well, I think Dylan's right actually, uh, and I think you probably think that as well

[00:34:08] I think to a certain degree I I think what they portray in um For all mankind and the new season's just about to come out on apple tv, by the way uh it's I I think it's showing The extreme end of the possibility

[00:34:29] um, but I I don't think in in real terms we would have achieved what they've achieved in that Series as a science fiction show In real terms today. We'd probably be much further down the track than we are And I think we'd probably be on mars

[00:34:46] in some sort of habitat by now, but um Um I I don't think it'd be as uh as glitzy as as it is portrayed in the show. I That's interesting. Yeah. Yeah. I'm just thinking that we'd be

[00:35:00] Somewhat further down the track but not to a great extent would be my feeling on it Simply because of the technological limitations that we would have faced Yeah, i've never seen um for all for all my you got it. You got to check it out. It's so clever

[00:35:16] Yeah, it's just an alternative history No way at all All we all we are allowed to watch is uh scandinavian scandinavian murders Well, there you go, you've got yourself boxed in scandinavia, yeah i'm boxing by that

[00:35:38] Uh, but so but i'm i'm relying on you andrew as my um For all mankind spy to keep me posted on what happens Well, I think the next season the next season because last season they ended up on mars this season. It's actually set in the future and

[00:35:56] They are now going way beyond that and and it gets into the realm of estero asteroid mining and and that kind of thing so um, it's uh, it sort of started with a bang because the russians were first on the moon and

[00:36:12] I don't want to spoil it for people who haven't watched the previous season because There was a big revelation in that about who was first on mars, but I can't I can't do that um, but

[00:36:25] It does sort of push the envelope in terms of human development in space uh technology and and uh It does sort of make you think you know, what if they did have unlimited resources? What if If

[00:36:40] The world had taken a different attitude and a different approach to space exploration early on would we be that far down the track now? My feeling is not quite we'd certainly be Probably much better positioned to do these things now than we

[00:36:57] Than we ordinarily would be but i'm just not sure we'd be as as far as that show Indicates in terms of human. So does the successes? Does the show? uh Does it imagine world peace or is there still?

[00:37:16] A political imperative to do better than your neighbors. There's still a political imperative to do better than your neighbors uh, and it's um, it's it's sort of evolved into a race between the united states and russia and the private sector

[00:37:33] Uh, that was okay in the last season portrayed the race to mars was was a three horse race and Well, it turned out to be a four horse race that nobody knew about there was a there was a sneaky phantom

[00:37:47] um player in there, but I can't I can't let the cat out of the bag for those who But it's um Yeah, and it was you basically had three missions heading for mars at the same time

[00:37:59] And I think in reality that probably wouldn't happen. Although we've seen it recently with the moon There were three missions happening around about the same time to the moon um involving the russians Yeah, um, sorry, but I think the way mars would

[00:38:18] And and we've talked about this before I think the way To successfully achieve a human mission to mars would be to collaborate rather than compete I don't I only think that's where the difference is going to be I um, I agree with that actually

[00:38:37] from my position of complete ignorance on the on the show, but I agree that um Uh, I think it will be collaboration in the end because it is you know, it is such a major achievement to get to mars

[00:38:48] um, I was just going to comment though that the idea of people setting off to mars at the same time isn't Isn't too fantastic because the windows to get to launch spacecraft to mars are every 26 months

[00:39:01] Yeah, and if you miss one, you've got 26 months before you you can do it again. So, um, it's uh Just because of the orbital geometry, but yeah, that's look you've I think you've answered that far better than I could have done

[00:39:14] Uh, and so, uh, yeah, so it's an interesting question and I i'm sure we would have advanced more rapidly uh just because you could you could throw infinite amounts of money at the technology and that would certainly refine things but

[00:39:31] When you throw in that political dimension though, you've got a whole lot of different aspects to think about. Oh, yes Yes, indeed. Thank you. Dylan. Uh, our next question comes from fenton Hello fred and andrew Enjoying the show as ever this is fenton in minnesota

[00:39:53] I have two related questions for you One is it possible to have two or more planets in the same orbit, for example opposing each other and What would have happened to mars or venus if this had been the case for us? Take it away guys

[00:40:17] Thanks fenton. So, um I'll get you to explain opposing orbits first up fred and Yeah, and then we'll get to the what if part of it uh, so well, so I guess what um What fenton means is, uh, you know planets on opposite sides of the solar system

[00:40:38] uh But in the same orbit plane Um, yeah and same or I think he means in the same orbit actually not the same orbital plane but And um We kind of we've already got that in terms of uh, the trojan asteroids that accompany

[00:41:00] Uh several of the planets including our own around in the orbit of the earth so what you've got is Uh stable points the two what is it the Third and fourth lagrange, sorry fourth and fifth lagrange points I can never remember which one is ahead of the planet

[00:41:21] Uh, so you you can put something else But one of those lagrange points and it will be stable and effectively, uh, you know, you get this scenario where objects actually orbit around those lagrange points In the same way as they do, you know, for example as

[00:41:41] As the james webb telescope and the gaia spacecraft as they orbit around the l2 Lagrange point which is on the opposite side of the earth from the sun Uh about million and a half kilometers away. So but that's not quite the same thing

[00:41:55] The reason why I raised that is that it shows that you can have objects which occupy the same orbit uh as a planet, but they have to be In particular positions in order to be stable I think that the certainly the detrojan asteroids are

[00:42:13] Examples of a problem where you've got two large bodies Namely the for example in the case of the ones in the earth's orbit You've got the earth and the sun and they their gravity mutually shepherds these much smaller orbits into those stable positions so um it's

[00:42:31] It it may well be that if you put, you know two equally sized planets Uh, then there are different characteristics and it may well be that you can only have them for example The the second lagrange point or something like that um

[00:42:48] I sorry the the third lagrange point which is on the other side of the sun from from uh, whatever the planet is so yeah, it's uh, it's an interesting scenario and It certainly would have changed the dynamics of the solar system

[00:43:01] The solar system would look very different with an object in it that was always on the opposite side of the sun Um, I mean there are some you know conspiracy theories that say that that's the case, but it's not yeah I've heard that one Yeah

[00:43:17] so and um, you know Yeah, had it been the case for mars and venus for example We would certainly have had different sorts of observations of the of the planets it's an interesting question Fenton and that's a waffly answer but um

[00:43:33] But it's uh, the only one i've got at the moment No fair enough. All right. Thanks Fenton lovely to hear from you. This is space nuts andrew dunkley here with professor fred watson

[00:43:47] Space nuts, uh now fred we got a text question from william. Uh, this is going to take a while to re How does gravity make planets round Uh, yeah that took quite a while did that it did so sorry I have to take a breath Yes

[00:44:06] So what you meant was how how does gravity make planets round? Yes, maybe I got the inflection wrong But uh, if I want to be really super technical I should have said how does uh gravity make planets spherical Yes, you should

[00:44:21] That's right. Um, and it's it's because um If you if you have a fluid and at the time That these objects became spherical. They were molten largely Uh, so you've got a fluid um, and what it wants to do is Pull itself to a central point

[00:44:46] That's what it's trying to do that's how gravity works It's trying to pull itself to some sort of central point and because that's happening in all directions uh this Gravity pulling is isotropic happens in all directions Then what you get is naturally a sphere

[00:45:04] it's um something that um you see uh with Bubbles of liquid in the international space station. Yeah, but it's not it's not gravity that does it there It's surface tension, but surface tension has a similar effect

[00:45:21] It tries to minimize the the size of the surface and I suppose in a sense That's what the gravity is doing, but it's a rather different Mechanism, so it's always pulling towards that central point and that just makes it naturally just just it's a natural state of being

[00:45:37] Basically It is yes for something big enough To have been fluid and for the gravity to overcome the resistance of whatever Whatever the you know is left, uh to whatever viscosity is left in the fluid the shorter answer william would have been because

[00:45:55] Which reminds me um on the cruise last week We went to a we loved going to a trivia section where if you couldn't answer the question you had to provide a dad joke And that was the fun part um, why did the chicken cross the road? uh, because

[00:46:17] I like that. Yeah, that's pretty good. Uh, let's uh get a An audio. Thanks. William. Uh audio question now from chris Hello Dr. Fred and andrew. This is chris foley In the united states, uh just outside of boston Love the show

[00:46:41] Um, you guys are great and it's my favorite podcast. Certainly my favorite astrophysics podcast Uh, my question is not related to black holes, but uh antimatter and i'm watching a documentary now Which is talking about the creation of antimatter Um through the decay of titanium 44 now

[00:47:08] I did not realize that antimatter was I thought it Could not be produced. I thought it was theoretical clearly i'm wrong But I was hoping that dr. Fred you could um expand on antimatter and how it is created and How much how often do we see it?

[00:47:27] Thank you very much Enjoy the show and uh all the best to you guys. Thank you Thank you, chris. Um lovely to hear from you. Hope all is well in the boston area um one thing I don't think we want happening is the expansion of antimatter

[00:47:43] Frequent expand on the idea but Not the not the yeah So so um antimatter Uh differs from normal matter In that it's got the opposite electrical charge And that's why a couple of minutes ago. We're talking about um when we're talking about turning energy directly into mass

[00:48:08] Uh, we mentioned that the mass that was produced was electrons and positrons So electrons have a negative charge positrons are the same thing but with a positive charge So it's all about electricity. It's about the electromagnetic force And yes, there are there are ways of producing antimatter Uh

[00:48:27] Not just the one that we described earlier in the show. Uh, it's um It can be done in uh large Colliders large particle accelerators Because there are certain collisions and certain reactions that actually produce antimatter equivalents which almost

[00:48:49] Certainly, uh, most commonly they just annihilate one another because that's what happens With matter and antimatter they annihilate each other. So, um, so yeah, so, uh, i'm not familiar with the process that Uh that chris was talking about regarding titanium 44 is an interesting one

[00:49:08] I'll check it out, but it's not unusual for antimatter to be produced in in these particle collisions And we believe that it was produced in the early universe as well And one of the problems that cosmologists face

[00:49:24] In trying to explain the way the universe looks is why that today As far as we know we see a predominance of matter rather than antimatter Whereas the mathematics seem to suggest that in the big bang, they should be created equally

[00:49:39] Matter and antimatter should be created in equal proportions But they clearly aren't because we've got an imbalance Uh, like we are surrounded by matter which is just as well because if we're surrounded by antimatter uh, it would be a bit violent so, um, so yeah interesting really interesting

[00:50:00] uh question About the production of of matter and antimatter, but it's even more interesting When it gets to to be a discussion about the origin of the universe because it's still one of those unsolved problems Uh, I did find just a one-liner from back in 2017 titanium 44 decays to

[00:50:21] scandium and then to calcium emitting positrons The antimatter equivalent of electrons in the second decay. There you go. So yeah, it does happen Well, thank you I had to try. Uh, okay. Thanks chris. Um,

[00:50:37] Uh, I think we um dealt with your antimatter which means we didn't answer the question next, uh, we We go to uh, nick who's got a really interesting question. Um, which Yeah, it's thought-provoking. I wouldn't have thought of this but uh, nick certainly did

[00:50:57] Hello friend andrew. This is nick lindsey here from perth Um, i have a question that takes us back to the moons And specifically the description that we use of the lava flows on the moon now

[00:51:13] Lava tends to be very viscous and in the low gravity environment like the moon or microgravity I should say I don't quite understand how it would flow Um, should it just not pond or build up like olympus mon has in mars

[00:51:29] And the other thing is that lava tends to be full of gas and should we not be seeing massive amounts of frothing Given that um, the gas is expanding into a vacuum Anyway, those are just comments. Um Love the show carry on Bye

[00:51:45] Uh, thank you nick. Uh, yeah, it's a good question because uh lava flows on earth are subject to a 1g environment uh The moon would have been quite different when it came to um, the the situation with its molten activity I imagine uh

[00:52:05] It's um, yes, that's right because I mean the that's the number one thing that's different The the moon's only got one sixth of the gravity of the earth um, but um, I think um I think nick is um

[00:52:20] generalizing a little bit more than perhaps a volcanologist would and in fact Volcanologist who I know best is also called nick nick petford Uh formerly of the university of northampton and who has been with us many times to look at volcanoes in

[00:52:35] Different parts of the world principally iceland. Oh, I'd love to hang with that guy He's probably a junkie myself Yeah, no, he's fabulous. Anyway, uh, well you will know if you're a volcano junkie that lava comes in different types. Oh, yeah

[00:52:51] Um, there's the ah, these are mostly hawaiian terms uh, it's um, it's Doesn't flow particularly quickly um and the hawaiians say it's called ah because that's what you say when you walk on it in bare feet because it's still sharp and got

[00:53:10] It got sharp points to it. Uh That's a Story, but it's a good one. Um, then another hawaiian term Pahoehoe or pahoho Uh, it's a much more viscous. Sorry a much less viscous lava Uh that flows very very readily indeed

[00:53:30] And it's what you see splashing around and that there's a you know when kilauea erupts That's what you see. Yeah, it's also splashing around. It's also called uh-oh lava Yeah probably is yeah, uh, but it's it's um, it's it's yeah, it's very very liquid very viscous

[00:53:52] Um, it would it would sort of settle down Uh without without too much fuss if you put it into a bucket um, and then there's pillow lava, which uh is what you get when lava is erupts under

[00:54:08] A water surface underneath the ocean. It's what you get forming under The ocean vents so uh, but I think I mean the as I understand it the lava flows on the moon are principally bustled Which means it's going to be our lava um

[00:54:24] predominantly, uh, but but I it clearly has enough of a flow to it that It can form these flat planes. Uh, it's what we see now when you look at those closely is uh

[00:54:39] You can see it covered by the lunar regolith. You don't you don't see the lava surface itself It's got a soil on top of it that has resulted from erosion caused by You know micro meteoroids caused by solar radiation all of that stuff

[00:54:54] So if it was frothy and bubbly You tend not to see it that would have been worn down because we're talking now about lava flows three and a half billion years ago Yeah, not recent

[00:55:05] um, even though they look relatively smooth I was looking at the moon last night through a little telescope and I'm always blown away by just how smooth those uh, those maria the the lava planes look

[00:55:17] And that's an illusion. They're not they're quite hilly and uh pop out with craters when you look at them closely, but On their large scale. They look very smooth So yeah, so I don't think there's an issue there. It's a good question though nick and um

[00:55:31] I hope that helps you to answer it. Excellent. Uh, thanks nick lovely to get your question and uh a reminder If you do have questions for fred Uh, you can send them into us via our website spacenutspodcast.com or spacenuts.io

[00:55:46] There's a couple of options there the ama tab or that little buttony thing on the right hand side. That's purple for some reason Uh, and yeah, keep them coming We've got a whole bunch, but we always want more so

[00:55:57] Send them into us. Don't forget to tell us who you are or um and where you're from We we love to know all about you, uh, how many dogs and cats you've got. Oh, geez, whatever uh, and Sorry

[00:56:10] Goldfish goldfish goldfish are very important in the world. Yes. I had plenty Had plenty of my life loved them My favorite was a little one called spot um He was good. Let me let me guess why he was called spot

[00:56:25] Have a go did he have a spot? He had a white spot on his body. Yes He did Um, he was so excited every time I walked in the room. That's why I liked him. He used to just go

[00:56:36] I was here. No, he actually probably was just going food food food food food I imagine uh, yeah, uh, but yeah send your questions in and have a browse while you're there check out the shop and uh Maybe you want to become a patron

[00:56:49] Uh, you can do that on our website as well spacenutspodcast.com Fred that wraps it up for another week. Thank you so much. It was a lot of fun. I love the thought-provoking questions Mm here here me too

[00:57:04] So i'll see you, uh, see you in a week or less or more who knows No, I I think I can manage that. I think that would be great. Yeah, let's do it. Let's do it for a change

[00:57:14] Okay, just for once in a week. Thanks fred. Catch you later So that sounds good take care fred what's an astronomer at large part of the team here at space nuts

[00:57:23] Hugh was unable to join us in the production booth this week. So everything went perfectly and for me Andrew Dunkley Great to be with you. Hope you can join us again on the very next episode of space nuts. Bye. Bye You'll be listening to the space nuts podcast

[00:57:41] Completely available at apple podcasts google podcasts Spotify iheart radio or your favorite podcast player. You can also stream on demand at bytes.com This has been another quality podcast production from sites.com