Quantum Light, Expanding Universes & Black Hole Mysteries: #502 - Answering Your Most Intriguing Questions

his food is. Uh, we're also talking about the minimum temperature of space, the effect of gas or on light and the starshot mission. That's all coming up in this edition of space nuts.

Professor Fred Watson: Yeah, he had a good walk with me this morning. I, I'm good fettle. I'm sure he did. Um, now you're so tall and he's so small, I bet his legs go 20 to the dozen. Professor Fred Watson: M quite cute to watch. Be like a little wind up. Professor Fred Watson: It's what it's like. Yeah, absolutely. Oh, gosh. Um, now I, I, I, we, we, we've got some questions, a couple of text and a couple of audio.

Now I uh, must, uh, preempt this by saying I had an eye check this morning and I had to have my pupils dilated. Right now what I'm looking at is absolute gobbledygook and it's very hard for me to read. Professor Fred Watson: So please, you want me to read it? I'll give it a go. Professor Fred Watson: Give it a go. Yeah, everything's, it's all double vision and blurry. Um, but anyway, let's, let's see what, uh, happens. Uh, this question comes from Jim in New Orleans.

I read where the Hubble telescope last fall. I assume you mean autumn for the people in the rest of the world. Um, I read where the Hubble

telescope last fall observed what appeared to be a plasma beam of 3,000 light years emanating from, from the black hole at the center of Galaxy M M87 doing well so far. That black hole was estimated to be 6.5 billion solar masses. I realized that questions concerning black holes are rather rare. Uh, on the podcast, however, I understand that When a plasma, uh, cools on Earth, it can either return to its original, original gaseous elemental state, or it can potentially

reform into completely different elements. Given the near absolute zero temperatures in space, I believe that at some point the plasma beam from, uh, uh, the uh, black hole at M. M87 will eventually cool. Rather than being cursed as the ultimate destroyer of matter in the universe, perhaps black holes should be considered the ultimate recyclers of matter instead. Love the podcast. Uh, all the best. Cheers. Jim in New Orleans. Uh, is he on the money?

Professor Fred Watson: Well, it's an interesting question. Yes. Uh, I mean, I think he's, he's right in the sense that the plasma, when it cools, um, will, uh, essentially turn, you know, what's a plasma? A plasma is an ionized gas. So it's a gas with an electrical charge. It's an electrified gas. When it loses its charge, it basically stays the same gas, uh, but is

cooler. Uh, now the completely different elements idea would involve nuclear processes because, uh, that's the only way you can change the elements, despite what the, um, what the alchemists used to try and do. Uh, you can do it with accelerators. Uh, and it may well be that, uh, the conditions in some plasmas, like the one from the M87 black hole, maybe they do, um, have collisions between the, uh, the ionized atoms, uh, that are of such high energy that you might split them

or something of that. So I'm not familiar with that because I'm not a particle physicist, but in that regard, yes, if that happens, you've got, uh, a nice recycling process which, um, you know, is what goes on in a nuclear reactor as well. Uh, but nice to hear from you, Jim. Uh, glad you're enjoying the podcast too. Yeah, um, there's so much happening when it comes to black holes. I mean, there's just. Yes,

you know, it's not just the plasma. It's, it's um, you know, the hunger, if I can use that term, black holes, uh, they get the munchies. They probably smoke too much pot. Professor Fred Watson: Um, is that what happens when you smoke too much pot? Apparently, I've been told, yeah. Yeah, Medical paper once, I spent a lot of time reading those. Um, but yeah, they're very active, um, parts of the, the universe. And there's so much we know that they do, but we don't know so much more about

them. And we've, uh, only in recent times been able to image them. Yep, not so much photographs, but, um, it, uh, was infrared, wasn't it? Professor Fred Watson: That's Radio signals in the Event Horizon Telescope. That's right. And that's where this image comes from that, that Jim's talking about. Okay, so, um, yeah, the. And, and we get so very many questions about them. They. One of the great

mysteries. Sorry. Professor Fred Watson: And I'll just correct what I just said. Uh, the, the Hubble telescope is certainly, um, what observed that, uh, plasma beam. Uh, but M87, of course, has had its, its structure, uh, imaged by the Event Horizon Telescope. Sorry, just. Just correcting myself there. That's okay. It's all good. Thank you, Jim. Professor Fred Watson: Appreciate. Uh, the question. Uh, our next question comes from, uh, one of our

regulars, Buddy. Uh, we'll see what, uh, he's got on his mind this time.

Uh, so 2.7 degrees Kelvin is the temperature of space. Uh, and, uh, if you think about what that temperature was when the universe was much younger than it is now, certainly, uh, in the aftermath of the Big Bang, that temperature was, you know, 5, 6, 7,000 degrees Kelvin. So as the universe has expanded, that temperature has fallen. And that 2.7 degrees is what we have now. And as the universe continues to expand, it will continue to cool, but not at a rate that would ever be

detectable by human instruments. But it is cooling. Um, whether that changes the, you know, the circumstances of clouds of gas or whatever is a different question. And I suspect the answer is no. Uh, it may, you know, it would have a superficial effect, but I don't think it's got any really fundamental effect on the makeup of the, of the cosmos. Okay, um, let's focus on the, the Kelvin scale for a

moment. Ah, it's, it's a measure of temperature based on the absolute, absolute zero, lowest temperature. Professor Fred Watson: That's right. And that temperature is defined by being the temperature at which all motion of atoms stops. So temperature is um, a vibration of atoms. So as a solid gets warmer, the atoms vibrate more. As a liquid gets warmer, the atoms sort of slosh around more. And as a gas gets warmer, the atoms whiz around

much faster, uh, in space. So um, the three states of matter there, uh, that, uh, that's to say that um, uh, at, at zero degrees Kelvin, uh, all atomic motion stops and we know it's absolutely zero. I think, um, some modern laboratories have got within a gazillionth of a degree of absolute zero. But it's one of those things you can never actually reach, uh, and get something that's whose atoms have stopped. As far as I know. Um, I might be wrong there, there might

be physics laboratories where that's actually been done. But. Right, well, if you have, you know, chances are if you did achieve it, you'd never get home from work. Quite, you wouldn't be able to move. Professor Fred Watson: Yeah, yeah. So, so obviously this is a dumb question, but, um, if you like, when you freeze a tray of ice in your fridge, you've got an old fashioned fridge like me where you have to actually get the thing out, fill it with water and put it in and.

Professor Fred Watson: Wait, you do that too? Yeah. Um, that's not absolute zero. So there's still movement. Professor Fred Watson: Yeah. In the atoms. In the atoms, yes, that's right. Professor Fred Watson: Even though the ice looks pretty inert, uh, the fact that it's probably, uh, well, absolute zero is minus 273 degrees Celsius. So if you're cooling it down to, you know, -13 or something, then you've still got another 260 degrees to go before you get to absolute zero. So there's

still plenty of movement in the atoms of your ice. Yeah. What about out in the depths of the solar system where the ice is so cold that it's the same as rock here? Is that anywhere near absolute zero? Professor Fred Watson: It's about um, uh, minus 190 on the surface of Titan, which is where ice is certainly effectively rock. It's as hard as rock, uh, hard as granite I think was the way, um,

Jonti described it last week. Yeah, um, but even then you still, you know, 83 degrees away from absolute zero. Wow. Uh, it's a very, very cold temperature. Sure is. Um, yeah, I, I, I, it's hard to imagine that kind of cold when the temperature outside here gets to 9 degrees. That's enough for me. Professor Fred Watson: Yes, yeah, yeah. Uh, so just to clarify one more point. Um, um, so absolute zero. Even though the universe is cooling, absolute zero is still absolute

zero. That's not going to alter. Professor Fred Watson: That's right. Yes, that's right. And, and the universe isn't at, uh, that temperature yet. It's 2.7 degrees above it still.

reach absolute zero. It might approach it asymptotically, which means it gets nearer and nearer, but takes longer and longer to do that. Right, okay. Very interesting. Great question, buddy. Thanks for sending it in. Good to hear from you as always. This is Space Nuts, Andrew Dunkley here with Professor Fred Watson. Professor Fred Watson: Three, two, one. Space Nuts. Now, if my eyes do not

deceive me, I have a text question in front of me. Or it could just be a message from my wife that I probably shouldn't read. Uh, no, it's a question. We know that light travels at slightly different speeds in different mediums. Uh, we also see different mediums affect light via refraction since this is somewhat related to the density of gas. Can pressure affect

this? Uh, if we go to the extreme case, is it possible for enough pressure, ah, of a gas, I assume cloud, or enough pressure of a gas in general to push back on light itself and stop it? That comes from Jacob in Western Australia. Um, I assume Western Australia. It could be an American state that has the abbreviation Wa I believe there is one, so could be either. But um, this reminds me of an experiment they did not so long ago where they actually did claim to have stopped light.

Professor Fred Watson: Yeah, that's right. Um, so you can stop photons. Um, and I'm not sure about the mechanism that is used to do that. It's not just pressure. There's more to it than that. I think it involves basically grabbing hold of photons using optical tweezers, uh, to stop the light. Uh, and so you can stop light. It's been done exactly as you've said, Andrew. But, uh, it's not just pressure. Pressures does have an interesting. I mean

it does affect the gas. So refraction, the refraction of gas is invent, is affected by the pressure of the gas. Um, what also is affected Is if you send light of a single wavelength through a gas at high pressure, um, it will spread into adjacent wavelengths. It uh, means that,

you know, the way we see it is as a spectrum line. If you send that light through a rain, sorry, a prism or something like that, you'll uh, end up with a single line of light corresponding to that color which corresponds to uh, a certain wavelength. Pressure actually broadens that and so these lines become wider. Uh, the process is called guess what? Pressure broadening. And um, um, that's what we see.

Uh, and that's actually how we can use light, uh, from stars to measure the pressure in the atmosphere of the star, uh, by how much the line of light is broadened. Okay, okay. All right. Um, I was just reading something that, um, because we were talking about the fact that they have stopped light in a lab, um, the way they did it was um, they used, as you said, a special medium like um, a cloud of ultra cold atoms. Professor Fred Watson: Yes, that's right.

Trapped the light's photons and it effectively brought the light to a complete standstill for a brief period. And that was work that was pioneered by physicists, um, uh, lean Howe, uh, from the Bose Einstein, um. Condensate. Condensate. Professor Fred Watson: Condensate, yeah. So, yes, your eyes aren't working. Professor Fred Watson: Yeah, well, you're doing well actually. You're doing very well. If I, um. The eyes that you've got at the moment, I couldn't read any of the stuff that

you're looking at. A, um, Bose Einstein condenser is basically, uh, it says peculiar state of matter where it behaves as a single quantum object. Uh, so you know, you put all the atoms together and they all behave like one object. It's a bit like entanglement. Right. It's headache y stuff, isn't it? Professor Fred Watson: It is, yeah. A very headache, yeah. Um, we gave uh, Jonti a lot of headaches while he was.

Professor Fred Watson: Oh, good. Well that's good. He complained his keep then every time. He was constantly having headaches. Um. All right, uh, so we covered Jacob's question effectively. Professor Fred Watson: I, uh, hope so. Um, it's uh, really all I've got to say about it. Unless you want to throw in a couple of. Oh no, you're getting into the realm of science fiction if you ask me to start talking about this. Professor Fred Watson: That's all right. That's perfectly acceptable.

Thanks, Jacob. Great. Uh, question. Okay, we checked all four systems, space nets, and our final question today comes from Ash in Brisbane.

universe and look at something, what would it be? And your answer was to go outside our galaxy and look back at it and see what it really looked like. Professor Fred Watson: Yeah, that's right. I think that's where that one's come from. Professor Fred Watson: Yeah. So if Starshot was able to do that, uh, how long would it take to get out there far enough for us to be able to look back and go, oh, look, there's our, oh gosh, we need to take the garbage

out. Um. Professor Fred Watson: Um, so, uh, the answer, rather remarkably, Andrew, is a number that you quoted in our last 400,000 years. That's right. So I'm doing that as a calculation in my head. So Starshot is the,

it's breakthrough. Starshot is still just a concept investigator, uh, that the idea with the project Breakthrough Starshot was to look at the possibilities of accelerating a spacecraft smaller than your mobile phone, uh, to something like a quarter of the speed of light so that you get to Alpha Centauri maybe in, um, rather than in, you know, 4.3 years. Um, you get there in 16 years or something like that. 4.3 years is how long it

would take for light to get to us. Uh, you could do it in 16 years if you were traveling at four times a, uh, quarter of the speed of light. With conventional rockets it takes about 60,000 years. So that's the difference. So if you. All right, so you accelerate your spacecraft to a quarter of the speed of light, I reckon you need to be 100,000 light years above the plane to see our galaxy in all its splendor. Because that's its diameter. It's

100,000 light years in diameter. So you push back, um, push out one, uh, hundred thousand light years, you'll see the whole thing, um, at, uh, a quarter of the speed of light, that's going to take you 400,000 years. So it's not as quick trip. No, no. And, um, yeah, it makes it very hard to um, to arrange really, because by the time it's there, no one will have remembered it, why it was. Professor Fred Watson: Sent, what it was. And then of course it sends back the photo. It's

800 years. 800,000 years. Professor Fred Watson: Yeah, that's right. No, um, actually it's not. It's 500,000 because, because the light travels back at, you know, speed of light. Speed of light, of course. Professor Fred Watson: Half a million. Half a million years for the full mission. Yeah. Professor Fred Watson: That's doable, I think, Andrew, don't you? Oh, you know, I, I'm, I'm a fairly patient person. I'm just sure I'm patient. That, patient enough for that?

Professor Fred Watson: No, me neither. Do you think Starshot will happen though? Professor Fred Watson: No, I think, I think the results that are coming out are promising. But uh, the Starshot is only a project to investigate whether it's feasible. Uh, so that will wind up. Then somebody's got to put the money in to not just build the spacecraft, which is probably quite cheap because it's small, uh, but to arrange for that Mylar, uh, light sail that's going to catch the light of

the laser. And the big ticket item is the laser itself. Yeah, we currently don't have a laser that's anywhere near powerful enough to uh, accelerate something to the quarter of the speed of light. Which leads me to um, uh, um, a question without notice because we've actually, I think in recent weeks or months had two or three questions directly related to sending a mission to Alpha Centauri using Laser United spacecraft. Um, this is not science fiction. This is feasible and

doable. We've uh, been doing all sorts of experiments with spacecraft sending up wooden satellites and things like that. But this would probably be one of the most efficient ways to send a long haul spacecraft to another place. Professor Fred Watson: Yeah, so you're quite right. It is doable, it's feasible. Yeah. Professor Fred Watson: Uh, but you need the technology which we don't have at the moment. And um, uh, I mean we should put a footnote in that. It has been done.

There's light sail experiments have already been done, uh, in orbit around the Earth just by the spacecraft deploying a very large sheet of Mylar, uh, and the ground controllers noticing the change in the acceleration of the spacecraft as a result of that. That's, that's been done and I think you and I covered it actually on one of the shows. Um, so the principle works. Uh, light sail, that's a principle that will actually work well. But uh, for the kind of figures that you were talking about

sending a spacecraft to Alpha Centauri. You need such a big laser, uh, that we simply don't have at the moment. And it may even. You might even have to uh, put it into orbit around the Earth, uh because if you had it on the ground it might fry the atmosphere or something like that. Oh, that'd be fun. Professor Fred Watson: Yeah, yeah, we do. Yeah, we really need that. Um, yeah, I love that it's

feasible. I have a sneaking suspicion that we could never do it out of Australia because of electricity prices and you're talking about leaving a light on for 16 years. I mean let's face it. Professor Fred Watson: Yes, and it's a big light too. Not feasible in Australia. Not with what we pay for. Professor Fred Watson: You get a bill.

Um, another thing that uh, has fascinated me in recent times, uh, and I read a couple of stories like this when you were away, Fred was uh, the ongoing development into new engine technology for space travel. And I know NASA's been working on something called the Deep Space Engine. Um, um, it's a thruster, uh, that uh, is showing a heck of a lot of promise in terms of its power. Uh, it's a low cost chemical compound

engine. Uh, it's lightweight, uh, and it promises to do some pretty amazing things if they can perfect it. We're on the cusp of probably achieving breakthrough technology in terms of speed and long haul space travel by the sound of it. Professor Fred Watson: Yeah, I think we covered um, some stories last year about EU ion drives and plasma drives and things like that which are all very promising.

Yeah, I, yeah, I think it's uh, it's a pretty exciting time and uh, there's a lot of development going on, a lot of money being poured into it because there are rewards to be gained if you can get out there. Professor Fred Watson: Yeah. Ah. And um, you probably don't like the idea but they're. You know, we've already spoken about uh, in the last episode or two about uh, asteroid mining. That's a, um, that's a

mission test that's been um. Well as we talked about in the previous episode, has fallen uh, foul unfortunately. But that, that's just the beginning. That's just going to be. Yes, it will continue on and of course mining the moon for that um, that, that mineral that's not so common on Earth. Can't remember the name of it. Professor Fred Watson: Something called water, I think. No, no, there's something else up there. Something else up there that they. Professor Fred Watson: Well, helium 3 is it?

That's it. So there's a lot going on and um, yeah, I'm sorry to say that profit's uh, probably the driving force behind. Professor Fred Watson: It in the end. That's right. It's a very human thing to do. Yep, essentially. All right, thank you, Ash. Thanks, uh, for the question. Great

to hear from you. And don't forget, if you've got questions for us, you're always welcome to send them to us via our website, spacenutspodcast.com or spacenuts IO and you just click on the little thing at the top called ama. Now, I know some time ago someone said, can you change it to something else so that we know where to send questions? Still working on that. Not sure where that's up to. I'll have to check with

Huw in the studio, uh, as to where that's up to. But, uh, yeah, the AMA M button @ the top is the one you click on. When you click on that, which I'm doing right now, you can send us a text question just, um, with your name, email address and the message, or you can click start recording. If you've got a device with a microphone. It's really quite simple. And while you're on the website, um, just randomly click on, oh, I don't know, shop. Speaking about profitable humans. And, uh, look at

all the, uh, Space Nuts paraphernalia. You can get

stickers, you can get T shirts, you can get mugs, you can get, uh, polo shirts, dad hats, bucket hats. Uh, for those of you that live in those northern cold latitudes, um, you can get a ribbed beanie, all with the Space Nuts logo. You can even get Space Nuts socks. Professor Fred Watson: I need one of those beanies for the next time we go up to the Arctic.

Yes, yes. Well, when we're up above the Arctic later this year, even though it'll be summer, the temperatures that we don't get down to here in winter, essentially. So we've bought ear muffs. So we should get some Space Nuts earmuffs, I reckon. Uh, there's also the, uh, the Space Nuts hoodie. That's a fun item if, you know, if you want to scare people. Not just Space Nut, but you've got a Space Nut hoodie on that'll freak people

out. Yeah, that's all on the Space Nuts website and plenty of other things to see and do there. And if you want to become a Space Nut supporter, you can do that on the Space, uh, Nuts website as well. And thank you to all of our patrons. Uh, um, we think you are awesome. Um, thanks for getting behind us. Uh, and did I say goodbye, Fred? Professor Fred Watson: Uh, I'm not sure whether you got there or not, actually. Thank you, Fred. Professor Fred Watson: Nice.

Good to talk to you, Andrew. And we shall speak again soon. We will indeed. And, uh, that's Professor Fred Watson, astronomer at large. And thanks to Huw in the studio, who couldn't be with us today because, uh, he actually thought Starshot was real. And, um, he went, bought a ticket, and it cost him a million bucks. So he's out, uh, doing his second and third job to pay it off from me, Andrew Dunkley. Thanks for your company. Catch you on the next episode of Space Nuts. Until then, bye bye.