May 20, 2021

Chinese Touchdown

Chinese Touchdown

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Space Nuts Episode 253 with Professor Fred Watson & Andrew Dunkley
●China successfully lands a Rover on Mars – now what?
●Our favorite...

For more Space Nuts, visit our websites. Links:
Astronomy, Science, Space, and Stuff.
Space Nuts Episode 253 with Professor Fred Watson & Andrew Dunkley
●China successfully lands a Rover on Mars – now what?
●Our favorite topics are back in the news – dark matter, dark energy and the expansion of the Universe – new modeling suggests a new answer in the form a new type of dark energy – maybe.
●Questions – from listeners in Kansas USA and Washington State USA (despite Andrew’s best efforts to move the whole state). Fred has answers for both.
●Did we mention that Andrew’s new book, The Hitler Paradox, is available as a e-book and pre-order for print editions? Just in case you missed it. Check the Shop tab at our website for details on how to order.
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Space Nuts 253 AI Transcript

[00:00:00] Promo Dude: 15 seconds. Guidance is internal gen nine ignition shake, lunch

nuts as the magic

Andrew: word. It feels good. Hello. Once again. Thank you for joining us. This is the space nuts podcast episode 253. My name is Andrew Dunkley, your host, and joining me as always are super special. Interstellar guest and colleague and friend, professor Fred Watson, astronomer LA.

Fred: Hi, Andrew. How are you going quite well.

You very well. Yeah. I'm all right. Thanks. Yep. Well good. You do too.

Andrew: Is that a polo

Fred: neck politic? Yeah. I difficult it that, um, I don't think, I don't know what they call it here. It's good. I think, um, I think it's technically a SKIVI yeah. Australia. Ah, yes.

Andrew: Yes. I used to wear those as a kid. I hated them. [00:01:00] I might as well where a new, but I have a rather large neck.

I went to a chiropractor once and he said, you've got the biggest neck I've ever seen. And I thought, gee, that's nice. I mean, it doesn't look. Abnormal to me. I think he made in terms of length.

Fred: Yeah. Maybe it goes from here to here. No, it's a long one.

Andrew: Yeah. I dunno. It gives me a lot of trouble. That's all I know.

I've got always got neck pain. Anyway. That's another story, you know, we've got an hour. I can tell

Fred: the whole thing. If you lock it. No,

Andrew: let's not. And we will though be talking about China successfully landing on Mars, and they're about to roll off their new mg. Now, hang on. It's a Rover. I'm not sure what model though, but we will be talking about that.

And, uh, I'm fascinated by this story. One of the things we've been talking about a lot in recent times is dark matter and dark energy. And of course, we've also been talking about the [00:02:00] expansion of the universe, but we don't know why it's expanding at a faster and faster rate, but now some new modeling suggests maybe we've got an answer and it's a new form or an undiscovered.

Yeah. At form of dark energy, maybe. Maybe that's the answer. Plus we'll tackle some questions. We've got one from Kansas and one from Western Australia. So we'll get into those a little later. Uh, the text questions we've been we've I know we love the audio questions, but we can't, we can't ignore our typing fraternity.

So we will be answering a couple of your questions.

Fred: But first, Fred,

Andrew: let us talk about China's mission to Mars. They touched down late last week, very successfully. Uh, and now they're, they're gearing up to, um, to, to roll that Rover out on utopia plan Nisha. I love the names of places on Mars.

Fred: Love them, the great army [00:03:00] and, uh, that I think.

The names of Chinese spacecraft are great, as well as you're wrong. It is the name of the, of the Rover, which is apparently a fire. God in Chinese culture might be pronouncing it incorrectly. And I do apologize for Chinese speakers to Chinese speakers if I am. Um, and the other thing to say is that this news might be able to date by the time people listen.

But the most, yes, you're quite right. The spacecraft got down safely last. Weekend, absolute triumph for the China national space administration. Uh, it is stunning that they've put this ambitious program together of, uh, an arbiter, a Lander and a Rover. And so far everything has gone absolutely smoothly.

They've touched down successfully on the surface with, uh, uh, uh, Essentially a technology, not that different from the way perseverance landed, except they didn't use a sky crane. They, the Lander [00:04:00] itself has a rocket motor, uh, down, uh, on its underneath. And that's used. To, um, that is used to, to slow it down, uh, as well as parachutes and the air shell, the usual stuff for slowing it down high in the atmosphere, but everything works swimmingly.

It is fantastic news that the spacecraft is there. Um, one thing. We might look out for is, uh, images from Highrise, which is the high resolution camera on board, Mars, reconnaissance, orbiter, and NASA and NASA orbiter. Uh, that will almost certainly eventually you send us back a picture of your own sitting on the surface.

Um, the, the news this weekend though, which hasn't come yet, but we're looking forward to is that, uh, either Saturday or Sunday, Uh, the, uh, is it the 22nd or 23rd, I guess? Is that, uh, well, what I'm reading, what

Andrew: I'm trying to do

Fred: is Friday or Saturday [00:05:00] 2020, the 22nd. That's right. Yeah. Uh, Friday or Saturday, uh, we expect, uh, the.

The land has ramps to come down, uh, and the, uh, the, the Rover to trundle down the, uh, the ramps and start its work on the surface. I'm sure they're doing this all with great caution as you would expect because, uh, it's, uh, it's something that nobody wants to get wrong. Uh, we've got this time delay with signals.

To and from Mars, I can't remember what it is at the moment, but it's usually as it can be as long as 20 minutes, it's usually shorter than that. Um, the Lander, the Rover weighs a quarter of a tonic. So, you know, not a, not a, not a minuscule thing. Uh, it's got, uh, solar panels, which I think, um, may already be on folded.

They were folded up for the landing. I'm not sure what the status of those. Is, uh, they probably need

Andrew: to warm it up don't they

[00:06:00] Fred: literally warm it up. Yeah, that's right. That will be the first thing that they do probably when it touched down. And of course that was the step in which the beagle to Lander failed back in 2003.

Was it, it. Touchdown successfully on the surface, but the solar panels didn't properly on unfurl. And if you could get over to bagel

Andrew: and, you know, just brief them open, would it suddenly come to life or would it be

Fred: dog by now? Yeah. Well, I think the problem is, I mean, it is. It was eight or nine years ago since that it's been on the surface.

Uh, and the problem is the electronics tend to freeze, uh, and don't recover at the sorts of temperatures that you can get during the Martian, the Martian night. They, they don't like being that cold. And when. You warm them up again? They just say no computer says no. So I love that.

Andrew: So all those fiction films I've watched about them, you know, finding an old Rover and reigniting it to escape the planet or [00:07:00] what not guy.

Fred: They are science fiction. That's right. Yes. No. All about that. Yeah. You do. I know, know more about it than I do anyway. Uh, so, uh, three months. Program for, uh, for as you're wrong. Um, and we'll do some really interesting things, including, uh, sensing the magnetic field, the local magnetic fields. I think I mentioned this last time, Andrew, it has a magnetometer, which is, I think the first time one has been sent to the surface, the arbitrary itself, Jan, one, one will stay.

Uh, operational for about two earth years, which is kind of one miles a year. Uh, and we'll, we'll do many things. I mean, in the short term, it's, it's, uh, acting as a relay station from as you're wrong. And we believe, I think, um, I got the news that, uh, it's it was within the last couple of days. It's always has been lowered to be, uh, near the surface of the planet.

So it can. [00:08:00] Pick up the signals from Jurong more easily, uh, cause it had a, quite a high or a bit before it's come down in height, uh, and we'll do that work, but it will continue for, as I said, the full Martian year, uh, to, to, to gather data, to. Image the surface, uh, and generally do a good stuff about Mars, which we will find out about I'm sure.

Uh, because I mean,

Andrew: it's yeah. When you, when you look at, sort of have on earth relationships between China and other countries, you know, there've been pretty dicey in recent times, but I would hope that when it comes to exploration of the planet, Mars, that they're a little bit more open to sharing. What they discover and, you know, I hope we in turn would share our information with them.

Uh, I think it's, it's good to have a, um, you know, uh, an, an, a nonpolitical approach to this and, and just share each other's discoveries and knowledge, and it can only be beneficial. [00:09:00] Holistically for the, for the whole world and for humanity. But, um, sometimes politics gets in the way and I suppose that's how the whole space race started.

It was all centered around the cold war and politics and, um, that got it off to a kickstart. But I, I think, I think we've got a much more cooperative approach to it these days. And cause you mentioned, um, Yeah, yeah. Taking photos of, uh, of the Rover on the Chinese, uh, on the Martian surface, the Chinese Rover.

How would they feel about that? Having a, you know, uh, another country's cameras on

Fred: them at the Lake, the cameras are probably on, on it, on us to us things that we do on this. So yeah, I suppose so,

Andrew: yeah, it's a fair point, but, um,

Fred: yeah, no, you're right in the world of. Science generally, um, certainly the fundamental scientists like physics and, uh, and astronomy, uh, there is a very high level of cooperation and, and part of it is about national pride.

Uh, you know, one of the reasons [00:10:00] why a lot of Australian scientists work with. Chinese scientists, particularly in sciences, like physics and things of that. So it's because discoveries might well be made. And if you've got a discovery made in a university in China, that's great. Kudos for the nation. Um, I guess the, the ultimate in that regard is.

If a Shiran finds unequivocal signs of life on Mars, um, before perseverance does, and that's not impacted civil, uh, not impossible, you know, it, it, it would depend what it was it's. Uh, life is certainly one of the questions that as young is, is equipped to try and answer, uh, looking for it's got ground penetrating radar, looking for subterranean water, as well as things of that site.

Uh, you never know what it might turn up. It will be very interesting and would certainly be a feather in the cap of the China national space administration. Well,

Andrew: I'll be totally honest, straight. I don't care who

Fred: finds it. I just hope [00:11:00] it's found.

Andrew: And that's

Fred: because you see that that's, that's the scientist in you coming out, Andrew, that we want to know.

That's the bottom line. That's the bottom line with science. We, we are curious people who want to know are curious in many ways. Absolutely. Now

Andrew: I've, I've thought of a question in regard to something that we were trying to. Figure it out earlier on, which is, you know, what day they were going to roll the Rover off the back of the truck, which is basically how they're doing it.

And it probably saved them millions of Yuan doing it that way. Um, but, um, and I love the concept of it. Just sort of going down a couple of ramps off the top of the Rover. I think that's fantastic simplicity in itself, but, uh, yeah, so we're talking the, um, the 21st or 22nd of May, but that's earth calendar.

Is there a Martian calendar? Have they developed one? Do

Fred: we know. Um, yes. And yes, there, there is, um, an it's based on muscle Sundays, which are called souls Marsh and days, 24 hours, 40 minutes, nearly more or less. Uh, and it's usually [00:12:00] what they usually do. They don't have a calendar in the same way as we do, that's the same everywhere, but for every mission, they count the number of days on the surface.

So, um, you know, I don't know what it is for perseverance. Now. It must be. Uh, Psalm 30 or 40 or something of that sort. Um, because it's, it's been the, you know, actually, no, it will be more than that. Be great in that, but you, you get the idea, uh, you count it from when the, when the mission starts. So when it lands on the surface, Hmm.

I think

Andrew: that was portrayed well in the movie, the Martian, because they referred to mission daises as souls. And then when, uh, when he, uh, I don't want to blow the end, but yeah, back on earth, they referred them, you know, suddenly they were going being day one, uh, rather than sole 34 or

Fred: whatever it was. Yes.

Yeah. Yeah. It was good. Um,

Andrew: all right. I just wondered because, you know, um, I suppose, uh, the day will come where someone is born. On another world. And how do you figure out the birth date? I [00:13:00] guess you figure out what day it is on earth and that'll be it.

Fred: That's the way we do things at the moment, but yeah, it might change.

You never know. You never know.

Andrew: Yeah. Yeah. Fascinating. All right. That there will be more to report from the Chinese mission on Mars. Of course. Um, I mentioned this last week, but we should mention it again. They've made history because they are now the third nation to land on Mars behind the United States and Russia.

So that is just an extraordinary achievement and, uh, they should be congratulated and I'm sure, uh, most of China is feeling very, very proud at the moment and that's, you know, we need a good news story given what's been happening in the world the last 18 months or so. Your with Andrew Dunkley and Fred Watson on the space nuts podcast.

Thanks for joining us. Let's take it break and get a word from our new sponsor. Nord VPN. If you're worried about your online privacy, you should be surveys across the [00:14:00] globe. Show that the number one concern with internet users is just that privacy. What you need. Is a great VPN service. Let me tell you about Nord VPN, which I've been trialing for the last week or so.

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If you've got someone who's hard to buy for, and you know, they're a fan of the show, perhaps that would be a great gift idea. So check it out at space nuts, Okay. Fred, let us move on to the next topic. I Yan, I read a bit up on this and this. Is fascinating. Uh, now we've talked many times about dark matter and dark energy.

Uh, we've also talked about how badly dark energy is named. Uh, but, uh, we're still trying to figure it out. We don't know what it is or why it exists, or, you know, we know it's there because there are just so many blanks in the universe and this stuff congregates in big clusters. A new theory has now been put forward as to, um, what might be happening with the expansion of the universe and dark energy.

And the thinking now could be that there is a new form of dark energy that is perhaps [00:18:00] filling in some of the blanks in the modeling of the expansion of the universe. Have

Fred: I got that, right? Yeah. You've left me nothing to say. Of course see you next week. So, uh, no, that's that's right. Um, uh, you know, just going back to basics the, uh, the, the two biggest unknowns are dark matter and dark energy, which are quite different.

Uh, dark matter is something like. Ordinary matter, except it's completely invisible and only reveals itself by its gravity. And it outweighs normal matter by about five to one. Uh, but dark energy is the, is it's not clumpy. Like. Dark matter is for a star, dark energy is a property of space itself. It's everywhere.

Uh, and we think it is probably uniformly distributed throughout the universe. That's the easiest assumption that you can make. And that's what cosmologists do. They, they take the most straightforward [00:19:00] line because it's the only one you can usually. So, um, yeah. And it's when you, when you look at the large scale picture of the universe, you can buy.

My looking, for example, at the way, galaxies are distributed and things of that sort, you can tease out the relative proportions of each. And it seems funny adding energy to mass, which we do, but, or taking them in the same sort of equation. But of course matter, and energy are equivalent in. By E equals MC squared.

So we ended up with a picture where, and this is very rough, but roughly 70% of the mass energy budget of the universe is dark energy. That's the stuff that's making the universe expand more rapidly. Uh, 20% of it is dark matter and 5% is the stuff we can see, which is mostly hydrogen. Uh, almost all of that is hydrogen.

So that, those, the proportion. So we're dealing with. The unknown [00:20:00] quantity. That is the biggest of them, all the dark energy. And it really is a big mystery. Um, so because we're not really able yet to say what dark energy is, what astronomers have done is concentrated on how it behaves. How, how does it reveal itself?

What are its properties and the simplest model? Of dark energy is what's called the cosmological constant. Uh, and this is something Einstein introduced actually into an equation, uh, back in the 1920s, uh, because. Is equations of relativity made the universe expand or contract. It was unstable. And at that time he didn't know that the universe was expanding because it was before I'd went in Hubble's discovery in 1929.

So he introduced this thing called the cosmological constant, which was, uh, you know, it's a, it's a kludge its effects in the equations to stop it, to stop the universe [00:21:00] from expanding or contracting, uh, But equally it could make it expand or contract even more. And that's how it's visualized now. So the name is Einstein's the cosmological constant, but what it is in furthers is, is an energy which is proportional to the amount of space you've got.

So, uh, basically for every cubic meter of space, you've got a certain amount of this cosmological, constant energy. And as the space expands, you get more energy. That's that's the bottom line, you know, the space is getting bigger, so the energy gets bigger as well. And that's, what's called, you know, what gives rise to the, um, the accelerated expansion of the universe.

So that's the background on dark energy. Hope you got that. Okay. But the story now cuts to another problem that we face in cosmology. And that is, [00:22:00] uh, that you can, you can check these parameters that I've just been talking about that the relative massive. Uh, of the relative energy content of dark energy, dark matter and normal matter, you can check them by looking at the, the way, uh, you know, for example, the, the, the small changes, a small differences in temperature in the cosmic microwave background, radiation.

This is the flash of the big bang, which is slightly rippled because of the unevenness in temperature, in that big bang. And we think that's due to the sound waves that we're pulsing in the, in the. Big bang itself. So, uh, by looking at those ripples, you can work out these parameters and in particular, you can work out what the expansion of the universe should be.

Now you can get that from these numbers, but you can also work that out by looking at distant supernovae exploding stars, which is actually how we found out that dark energy exists in the first place. [00:23:00] So you've got these two ways of. Understanding the expansion of the universe. One comes from sick for 400, sorry, 380,000 years after the big bang.

That's when the cosmic microwave background was sort of laid down. That's what we're seeing. We're looking back so far. We see, still see this flash of the big bang, which is now in the microwave space. True. So you can do it with those and you can do it at. What is not quite the present time, but is certainly within a few billion years of the present time by looking at these supernovae.

And the problem is you get different answers. Um, they're not, they're not wildly different. I have to say, I can't remember what the differences is, but it's in the region of three or 4%. Maybe a bit more than that. Maybe 5%, which by modern standards is quite significant. So when, when I was involved in cosmology, back in the 1970s, an error of a hundred percent was, was acceptable because nobody knew [00:24:00] what was going on, but now we've, um, we've entered an era.

Of precision cosmology. That's a phrase that was used by my PhD supervisor, Malcolm along air, then astronomer Royal for Scotland who decreed in a meeting one day, we are entering this gray phase of precision cosmology. Sorry, Malcolm, if you're listening, that's a very poor impersonation of your voice, but, uh, precision cosmology.

And that's where we are now. So an error of. You know, four or 5% or whatever it is, is significant and it's worrisome. And so scientists have been worried about that now to come to the story. Are you still with me? I have got to sleep. I've got bored and wandered off. Yeah. The story itself starts here because scientists at the university of Southern Denmark.

Have I've looked at this issue, that the fact that, uh, the, the expansion rate of the universe, you get a different answer for it, depending on where your, what, what timescale you're looking at. Uh, and they have [00:25:00] introduced something which they call. Uh, new, early dark energy. Uh it's it's got an acronym, which I love it's needy.

Uh, we've got a cat that's needy. Uh, so something to do with

Andrew: dark

Fred: energy, you know, they're all needy that's right. But new, early dark energy, what they're suggesting, um, this group of scientists is that there is, uh, Uh, a different sort of dark energy, which was prevalent in the early universe. That's the needy, the new early dark energy.

Um, and then at a particular time in the expansion of the universe, it settled down into being. The dark energy that we measure today. And if you plug that into your equations, then the problem goes away as you, as you might expect, because you're changing the nature of dark energy, but what they liken it to is a phase change.

And by that, I [00:26:00] mean, uh, by a phase change, we mean, for example, in the case of water, uh, water can go from ice to a liquid, and that is a phase change. It changes its phase. And to what they're suggesting is that maybe this early kind of dark energy, the needy stuff, uh, was a different phase from the dark energy that we see today.

And so they imagine a transition between the two at some stage in the universe. Uh, where, uh, in fact what they, uh, in one of the scientists, um, I can, I can read what he, what he said, Martin slot. Uh, it is a phase transition where many bubbles of the unit new phase suddenly appear. And when these bubbles expand and collide the phase.

Transition is complete on a cosmic scale. It is a very violent quantum mechanical process. That's what he says about it. So it's a really an interesting idea that we've got two different kinds of dark energy. Uh, but they're related to one another in the same way as ice and water, both water, but they're in different phases.

[00:27:00] Um, and, um, Well, it'll be interesting to see how the cosmology community, uh, the astrophysicist to think about the big picture stuff in the early universe, how they react to this. And, um, I will be speaking to one of them over the internet tomorrow. I might, I might throw this one his way and ask him what he thinks of it.

They're very respectful. Well, I it's clever

Andrew: thinking actually, you know, on the surface, you, you generally think of one. Possibility and you get fixated on that. So for someone to say, hang on a minute, you know, there might've been a different kind of dark energy at some point. And who's to say there are more than one now.

I mean yeah. Using the water analogy. Yeah. Water as a liquid water, as a solid, but it's also available in gas and vapor. Yeah. So, you know, if water, if water has gotten multiple functionalities like that, so many other things probably due to

Fred: indie [00:28:00] rock rock,

Andrew: and be a liquid. If

Fred: the conditions are right. Oh, that's right.


Andrew: indeed. All right. Well, we watch with interest with chipping away at this dark matter, dark energy puzzle. I still find it hard to get my head around the fact that the universe is expanding at an accelerating rate. In all directions. Um, and you know, what's filling the space and more space. It's, it's sort of a self, um, generating scenario.

Isn't it? Um, a self fulfilling prophecy, if you like, it's just. It is happening. We know it, but, uh, so many mysteries surrounding the why's and wherefores, uh, which we are, we're going to answer. We'll have that answer for you next week. In fact,

Fred: possibly Norm's Andrew. We might have the needy bit by next week, but I've got to say a couple of

Andrew: times over the years, we've said, now we don't know why this [00:29:00] is happening, but one day we'll know.

And then a week later we've had the answer that has happened to us, I think twice, but maybe not on this occasion, there will be probably more theories and hopefully some answers with dark energy in the.

Fred: Future. I don't

Andrew: know how far into the future that might be done. This is the space and that's podcast.

Andrew Dunkley here with professor Fred Watson space


Now Fred, uh, Hugh sent us a, an interesting email this week, which I thought was worth a mention. It's basically an analysis of people's activities when it comes to listening to podcasts like ours, and they've basically ranked. All of the space related podcasts.

And I'm very happy to say that we've made the top 10, which I, uh, I'm I'm gobsmacked about. Uh, there are some other fantastic podcasts in [00:30:00] there. And, uh, I do like to recognize, um, other people who, who do what we do because, um, you know, it's become the new wave of spreading information. Th th the number one space podcast.

I just love this. This is from NASA. It's called Houston. We have a podcast. I think that's fantastic. And the list goes on, uh, you know, and a lot of these are interview based podcasts and, um, uh, others are just sort of chin wag is like us. Uh, I think what sets us apart to a certain degree for it is audience participation, because we do invite people to send us questions and to use their own voices in doing so, but out of the, um, uh, space-related podcasts that are being downloaded around the world right now, we come in at number eight.

And we're the only Australian space podcast in the top 10, which I think is fantastic. I am so thrilled, uh, that we're receiving that, [00:31:00] that sort of recognition and, uh, um, um, you know, I'm chuffed really chuffed. So, uh, thank you to all our supporters who. Put us there because without you we'd be just too all black, right.

Sitting around talking to each other, which for the first three years was, but, uh, it's good. Uh, and, um, also, uh, you know, that that sort of support is reflected in some of the social media. Uh, activity that we have with, uh, the space that's podcast group that was created by the audience and the, the, um, the idea of signing up patrons to financially support the podcast was a listener idea.

So, uh, thank you again. Uh, we are, we are so, so thrilled

Fred: now,

Andrew: speaking of. For audience participation for it. We have some questions. The first one comes from Scouser, who I believe is also a character in a super Mario game, but a Scouser is in Kansas. And, uh, he [00:32:00] says, uh, I'm assuming he could be a shoe. Hey guys just stumbled across this podcast concept last year, while avoiding the noise on TV surrounding the political bleep, um, here in the U S.

Anyway, I heard Andrew begging for questions. I don't beg, I probably asked politely, I heard Andrew. Asking politely for questions on the drive home from work the other day. So here goes, I think I understand why the observable as observable universe is 93 billion light years in diameter. When the universe is only 13.7 billion years old, I E the universe expanding faster than the speed of light.

The further away it is, et cetera. I suspect the James Webb space telescope will uncover a bunch of surprises out there, uh, when it comes online soon. But using the telescopes we have now, have we ever observed anything, crossing the boundary at the edge of the observable universe? I imagine it's not this simple, but have we ever looked at something [00:33:00] at the edge of the observable universe, only for it to disappear across the boundary.

The next time we went looking for it. Thanks. Keep up the good work. I, I love this question. Uh, because yeah, that we have a limit to how much we can see out into the universe. And we don't know what's beyond that. And it's only a small percentage of the universe that we can actually observe, but have we ever seen anything that was right out there and near the edge and then not, it's not there anymore because it's crossed the threshold or is that just not possible?

Fred: It'll look, it, it will be if the threshold was near than it is because, um, the horizon. Yeah, the question's quite right in that. One of the horizons of the universe is things expanding. You know, you get to a distance where the expansion of the universe is such that. The light [00:34:00] leaving those objects will never reach us.

It will never make it to us. Uh, but that there is a nearer horizon than that. And it's what we've just been talking about. It's the cosmic microwave background radiation. Um, and that's the backdrop to the universe. What you're doing is looking back to a time. When the universe was still glowing brightly, um, it, it, it would have been glowing with visible light in fact, at that time.

Uh, but that radiation as it's traveled through the universe for the last 13.8 billion years has been stretched into microwave. So that's what we see. Um, there is, uh, there's this kind of subplot to this question, which I might just talk about briefly for a minute, uh, and scars. This says, I think I understand why the observable universe is 93 point.

Sorry, 93 billion light years in diameter. When the university is only 13.7, we're authentic.  probably billion years old. And, um, [00:35:00] that is to do with the difference between the look back time, uh, which is the 13.8 billion years and the sort of physical diameter of the universe. So what what's happened is, um, The universe has expanded so that if you could see it all at once and we can't, and we never can, uh, the, the, the radius of the universe is, is roughly 45 billion.

Light years. Um, but because we, because the universe has been expanding since that time, um, we, uh, we only see it as, as though it hadn't expanded. In other words, we see it at 13.8 billion light years radius. So in fact, saying that the universe has a radius and apparent radius of 13.8 billion light years is really misleading.

Uh, and, um, the way scholars has put it is much better. The universe is. 93 billion, light years in diameter. The [00:36:00] university's only threat 13.7 billion years old. So what you're doing is you're contrasting a physical dimension with a look back time. Um, I think I've made a bit of a meal out of that, which we might not dwell on it, but that's the difference between those two.

So what, when we look at the cosmic microwave background, as I mentioned a few minutes ago, what we see is all these ripples on its slight ripples in temperature at a level of one part in a hundred thousand. The the temperature, the average temperature is 2.7 degrees above absolute zero. And there are variations on that at the level of 0.0, zero, zero one degree.

So, um, that's what the ripples are and they, uh, we think they were imprinted on the. Cosmic microwave background, um, by sound waves, what we call baryonic acoustic oscillations oscillations in the, in the, the, the plasma there that the glowing, um, brightness of the [00:37:00] universe. Um, so the surface that we see, if you can imagine it, and it's sometimes called the last scattering surface, that surface.

How's these ripples on it, but it itself is moving away from us at the speed of light. This is where it gets really weird. Um, uh, that's an artifact of what causes that. So what you could say is that yes. Maybe you might see changes in it over time, but the bottom line is that the time that we have available as humans is far shorter than what you would at what you'd have to wait for to see any change in the ripples on the cosmic microwave background, radiation, um, it's.

It's uh, that that's sort of turning the question a little bit inside out, but that's the city, right. That we're faced with, rather than things crossing the boundary at the edge of the observable universe, which we don't see. [00:38:00] And that's because when we look back to the cosmic microwave background, radiation, there weren't any discreet objects in the universe at all.

It was still an amorphous. Plasma. Um, it was only later when the, the first stars and galaxies started coming along. So, um, and you know, we can, we can sort of see beyond those in, in a sense, so we don't see things crossing the boundary, but a great question. Thank you very much. No, sir. I'm sorry. It took us 10 minutes

Andrew: to tell you no.

Fred: Yes, that's true. Did that take 10 minutes? I'm so sorry. I don't know.

Andrew: That felt like,

uh, thanks guys. I lovely to hear from you. Okay. We're not in Kansas anymore. We're going to Western Australia with a question from Gus. Thank you. Love the show. I've been thinking about higher dimension unification theories, a lot lately.

Fred: Could I just stop me too. [00:39:00] I'm sure that's not Washington. Oh, could be, Oh,

Andrew: WWI.

Yeah, look, couple of your way is

Fred: that's a good point. This of course sounds a lot more like an author

Andrew: does not sound like an Australian place, I must say. Yeah. So my apologies, Gus, I put you in Western Australia. It's a nice place by the way. Um, but now you're in Washington. All right. Uh, Gus, thank you. Um, love the show.

I've been thinking about higher dimension unification theories. A lot lately. I read a lot about string theory in college. I never quite got the notion of another dimension until presented with the analogy of an ant on a two dimensional line. Two ants on a 2d line can't cross, but if they can act in another dimension, walk around the line like itself, uh, like one of these proposed additional dimensions and raise their environment, uh, raise their environment, um, their world to 3d.

[00:40:00] Uh, that we can't perceive except for the ants crossing each other. Ah, okay. That's the setup to the question. Is this a reasonable candidate for spooky action at a distance? Are we conceivably seeing the ant cross in some way? When we talk about quantum coupling, uh, just a guy who likes thinking about things.

Yes, you do. You've got an amazing mind. Um, if I hear this on the show, I promise to be super excited. Well, we're excited and they're going to

Fred: tackle this one question. Gus is a great question. Um, and. That's very like, uh, the kind of thinking that goes into it. It's, it's a bit more subtle than that, but, um, so the, the quantum coupling that Gus is talking about is what we normally call quantum entanglement.

And maybe you remember that, um, if you get to subatomic particles that, [00:41:00] uh, I have so much in common that they behave in a quantum fashion, just like one particle. And that's what entanglement means. And then you take one a long, long way away and you do something to it. Namely, look at it. The other one instantaneously react.

It says, Oh, I'm being looked at. And, uh, and you know, it, it reacts. And that's what I in styling called spooky action at a distance, which is where that quote comes from. So, um, So people, I think it's still fair to say, uh, there are, there are subtleties where that whole thing actually, but the, but I think it's fair to say that this is not well understood.

And there are certainly quantum physicists who believe that what we're seeing here is evidence of a, of a deeper layer of reality. If I can put it that way, be up below what we, what we perceive. In quantum mechanics and what we perceive in relativity, the two basic theories that tell us how the universe works.

Um, and so there's this [00:42:00] idea that there is new physics. It comes from many other different considerations, but one of the possibilities of new physics is yes, that there are additional dimensions that we can't perceive. And that analogy that Gus has given is a perfect example of that. The two ants walking on a 2d line, uh, that suddenly.

Find they're in three dimensions and they cross one another, but we can only see the two dimensions. So it looks as though they've done something really weird come together and then separated again, a very nice analog, um, uh, several of the current theories, uh, of. The universe, including string theory, uh, require higher dimensions.

In fact, I thinks some flavors of string theory requires 26 dimensions. And the only ones we can see are the four of space and time, three dimensions of space, and one of time, um, the, one of the ways that string theory. Gets around. This is the idea of what, what [00:43:00] they call compactified dimensions, where the dimensions are actually wrapped up, uh, around a string.

That's got essentially zero diameter. It's very strange things to think about. Uh, but there's another version of this called M theory, which is probably a membrane theory or something like that. Magic theory, uh, which suggests that. Um, our perceived dimensions you can think of as membranes on a two dimensional or dimensions on a two dimensional sheet, uh, which, uh, they exist in a higher dimensional space.

And that's, I think that's a fairly, uh, well-known theory. It's only a theory. There is no evidence whatsoever that this is true, but. People are working on it. Uh, but that leads you into the idea that each, you know, there might be multiple universities, each one having its own membrane, uh, which is the one of the cornerstones of M theory.

And so once again, you've got this, um, that the existence of multiple dimensions, which raises the [00:44:00] possibility that these weird quantum effects that we see might be because things are crossing into additional dimensions. This is hand-waving stuff. It's very waffley um, from me anyway, uh, a lot of the scientists who were working on this, uh, building very serious mathematical theories to try and explain it, but the, the thing that's lacking at the moment is evidence.

We just have no evidence that any of this stuff works except for entanglement, which does work. Yeah.

Andrew: I suppose that's your foothold, isn't it. Into the post concept. Mm mm. All right. Gus. From Washington, I'm going to lobby the Washington state government and the West Australian state government and see if they can work out a different way of demonstrating the abbreviated form of each individual state, because it's not working for me.

Fred: It's just not, well,

Andrew: it's clearly not w they're both WUA

Fred: and

Andrew: we often refer to Western Australia as WWI. We didn't happen [00:45:00] to Washington.

Fred: What I want to do just before we go is yes. In fact to check. If where is it? Washington USA. There it is. It's a quilt. Ah, you found him? Yeah. Okay. We use this

Andrew: Chinese spy satellite to do that,

Fred: by the way.

Otherwise known as Google maps. Yeah, it looks great. The nice part of the world, ah,

Andrew: that is a beautiful part of the world up around that. Um, those Northern American States, the Northwest. Beautiful. Lovely. Northeast is nice too. In fact, um, most places I've visited in the United States were, were lovely. Uh, even the deserts, uh, they're prettier than ours.

How's it just rock and dust and dirt. At least you've got some plant life in yours. And I w w as not too bad either. That's the thing that the planets, every, every week, yes, it's different. Um, although I'm told, I'm told by a friend that has visited [00:46:00] Texas, that it's very much like the area I live in out here on the Western Plains.

Uh, if you, if you plucked someone out of Dubbo and dropped them in Texas, they wouldn't feel like they were anywhere else. It would, you know, cause they're so much alike in terms of terrain and grassland, et cetera. I haven't tested the theory yet, but maybe one day when all this pandemic stuff is over with.

Uh, thank you again, Gus. Lovely to hear from you. Sorry about missing up


Andrew: locality. Um, you know, Globalization and all, it'll probably all come together in the end. Uh, and thank you for, uh, always great fun. Nice to see you and chat again. And we'll catch you again

Fred: next week. Sounds right. Thank you very much.

Andrew, take care. Have a good week. You too. Fred

Andrew: Watson astronomer at large part of the great big team of two plus one here at the space, nuts podcast and hello to hue in the studio who, well, we don't know what he does, but he's there, which is the main thing. And for me, Andrew Dunkley, thank you for joining us.

We'll catch you again [00:47:00] next week on another edition of the space NATS podcast. Bye for now.

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