#430: Dark Energy Theories & Voyager's Cosmic Rays: Your Queries Answered

[00:00:00] Hi there, this is Space Nuts where we talk astronomy and space science. My name is Andrew Dunkley, your host. Good to have you company. This is our Q&A edition where we take audience

[00:00:10] questions and we chop them up and throw them out because we don't know the answer to anything. But we are going to attempt to discuss atmospheric tubes. Now this is a question that Jeff's come up

[00:00:22] with. It's a sort of a what-if question so we'll look at that. Patty is asking questions about Voyager 1 which has been in the news lately and Oliver, one of our younger listeners, is talking radiation, dark matter and dark energy all coming up on this episode of Space Nuts.

[00:00:41] 15 seconds guidance is internal 10 9 ignition sequence start space nuts 5 4 3 2 1 2 3 4 5 4 3 2 1 Space Nuts. Astronauts report it feels good. And we say hello once again to Professor Fred Watson, astronomer at large. Hello Fred. Hello Andrew, fancy seeing you here. Yes, welcome back. It's

[00:01:06] been minutes. Not even sure it was minutes. I think it might just be seconds. Seconds, not a bad tube. You think this joke's getting a bit old now? Oh yeah, it's pretty awful isn't it?

[00:01:18] But you know, Space Nuts is known for one thing, it's bad jokes. Terrible jokes, horrible jokes. Yes, we'll keep them coming too. Shall we get straight into it? No, no, let's fill the intro out.

[00:01:33] Yeah, okay, fair enough. What I do love about Space Nuts is we've got people listening all over the world, lots of questions coming from different parts of the planet. But we do have a young

[00:01:47] audience too, which I think is one of the great things about it. Having young people having such an interest in astronomy and space science. One of those people is Oliver. And

[00:02:00] Oliver's got a pretty curly one, but he's got his own ideas on this as well. Let's see what he's on about. Yeah. Hello, I am Oliver from Queensland. I was just wondering a pretty interesting question.

[00:02:13] So you know that a black hole creates radiation, how come it doesn't get immediately sucked in? Does that mean the radiation has to go faster than the speed of light? But what if it's just

[00:02:25] going a bit faster? But what if black holes could create dark energy? That would actually solve a lot of things. And if dark energy, what if that combines with matter particles and that creates

[00:02:38] dark matter? I think that would make a lot of sense. And with little things that can go past, it goes over there and makes the border of the universe grow even faster and faster. And when

[00:02:52] it grows faster and faster, the reason it grows faster and faster, I know I'm saying faster and faster a lot, but what if it goes faster and faster because there's more space for the radiation to

[00:03:04] not collide with other matter particles so it can go to the border of the universe quicker? So we can't tell because it's there, because it's going so fast our telescopes like the Hubble

[00:03:16] Space Telescope can't see it because it's going faster than the speed of light. It's just a quick question. Thanks. Love the show. Goodbye. Please tell me a good answer. Well, I don't really care

[00:03:27] as long as it gets solved. See ya. I love that ending. Oliver, that's brilliant. Gosh, there's a lot in there that we've got to unpack. The first part was about radiation. How come radiation from a black hole doesn't get sucked straight back in? That's a good question.

[00:03:50] It's a great question. And, you know, thank you again, Oliver, for getting in touch with us and for bringing a breath of fresh air to our questions. It's great to have your voice.

[00:04:04] I'm revved up by his excitement. Me too. I really am. Me too. So we think that Hawking radiation or the radiation that's emitted from black holes doesn't come from the black hole itself. It

[00:04:16] actually comes at the event horizon. So the event horizon is that sphere, it's an imaginary sphere around the black hole. But it's the point where the black hole's gravitational attraction stops any light emanating from the black hole. So outside the black hole, light can travel around.

[00:04:42] Inside the black hole, it can't because it just gets pulled back in. Sorry, outside the event horizon, light can travel around. Inside the event horizon, it just gets pulled back in. And we think

[00:04:53] Hawking radiation, well, it seems to be the case that it's formed by what we call virtual particles, particles basically coming into being and disappearing again. And they come into being in pairs. And if one of the pair is inside the event horizon, and the other one isn't,

[00:05:11] then the one that's outside the event horizon gets away and can travel because it's not within the region where the speed of light isn't enough to get away from the black hole. I hope that makes

[00:05:23] sense. But that's why the Hawking radiation doesn't just get pulled back in. And it is electro, excuse me, it is electromagnetic radiation. It is a mixture of the different wavelengths. It's probably pretty low energy. And we have never detected it. But the theoretical basis

[00:05:43] is sound enough that we are pretty sure that it exists. Okay. What leads by the way to the evaporation of black holes, it's an energy loss from black holes that over billions, many billions, perhaps 10s of billions of years, the black hole will evaporate and disappear.

[00:06:03] Okay. So that's one part of his question. Yes. He goes on to ask about a black hole being the reason the dark energy exists. Now there are some theories and studies going on that suggest this.

[00:06:20] That's right. We've covered that. I keep meaning to relook at that paper just to work out what the mechanism is. But that is certainly a view. If I remember rightly, was it Japanese scientists who

[00:06:34] postulated this? I can't remember. We should look back at it and perhaps do it in a bit more detail sometime. But yes, there was this view that perhaps phenomena taking place within black holes

[00:06:47] are what lead to the dark energy of the universe. The only issue with that that comes to my mind is that we equate, we believe and the evidence seems to be that the dark energy of the universe is

[00:07:02] totally uniform, that it's the same everywhere. And if it was something to do with black holes, you might think it would be a bit bumpy where the more black holes you've got in one part of space,

[00:07:11] the more dark energy you've got. But that doesn't seem to be the case. So I do need to look at that again, Andrew. Okay. But see, therein lies the problem with dark energy. We keep coming up with

[00:07:28] new theories, new ideas, new problems associated with those new theories and new ideas. And it just keeps going around and around and around. In our last episode, the question came up as to how

[00:07:39] the galaxies and galaxy clusters can possibly exist as they are if there isn't a dark matter halo big enough to cover it. So have we got our thinking wrong? Well,

[00:07:51] yeah, I don't know. And then Oliver goes on to ask if dark energy could, as it moves through the universe, affect particles and become dark matter? Could there be a relationship between the two,

[00:08:06] even though by name they're not actually very accurate or much of a relationship at all? They're, well, their names are, they're both called dark something. And that's probably where the similarity ends. Yes. Very different in their nature. And yes, it's a good point.

[00:08:28] Oliver talked about there being more space in the universe as the dark energy makes it expand. Things can travel to the boundary of the universe more rapidly. We don't actually know if the

[00:08:38] universe has a boundary or not. We suspect it may not have, it may be infinite. The boundary that we can see is a horizon, the cosmic microwave background radiation, which is what blocks our

[00:08:49] view beyond so that we don't see the more distant regions of the universe. The universe might be very big indeed. The bit that we can see might be quite small in comparison. So, and faster than

[00:09:05] light travel. I mean, Einstein's theory holds true that in space itself, nothing can move faster than light. Space itself can and probably did during the period of inflation. But, and it may do again if dark energy keeps on accelerating the expansion of the universe so that one day

[00:09:26] the universe is so big that some things that emit light, it never gets here because they're those that are carried away faster than the speed of light by the space itself, but not the light moving through it. So, interesting questions there. I do like your thinking,

[00:09:43] Oliver, and I hope as time goes on we might hear from you again. Oh, that'd be lovely. Oliver, thanks very much for getting in touch with us and don't lose that youthful enthusiasm ever because it is such a ray of light and I really appreciate

[00:09:59] hearing from you. This is Space Nuts, Andrew Dunkley here with Professor Fred Watson. Pleasure, you're live and very hear also. Space Nuts. Now, Fred, to a text question that came in from Patty. Hi guys, thanks for answering my last

[00:10:15] question about the end of life. I remember that one. I remember that one. Yeah, thanks Patty. So, here's a more boring one or four. After Voyager 1's recent drama, what is a cosmic ray

[00:10:30] and how come it affects Voyager and not computers on Earth? Did NASA have to get people out of retirement to reprogram the 70s computer? And he's made a reference to the movie The Martian where

[00:10:42] they had to do that for the Pathfinder mission that they had to reinvent during that show. Three, how can NASA hear such a weak signal? I've seen the DSN website and the signal looks

[00:10:58] weaker than a mouse fart on the moon. He's got a great turn of phrase, hasn't he? Yeah, it's a technical term though. Yeah, it is. I know we can shout really loud to Voyager but the return signal is so weak. Four, will New Horizons ever overtake Voyager

[00:11:15] given it's smaller and launched on a bigger rocket? I think that's more than four but that's a full episode covered. Thanks again guys. Patty from rainy Northern Ireland, home of the Amar

[00:11:29] Observatory where at the age of eight his interest in space began. Now a granddad. So, it wasn't yesterday. Yeah, great questions Patty. And Amar is a wonderful place. We visited Amar a few years

[00:11:44] ago. I know the director there very well. He's a colleague of mine from my Edinburgh days and also here in Australia. He worked for many years in Australia, Michael Burton. So, let's go to the

[00:11:58] beginning. We've got a list of four here. What's a cosmic ray? Well, it's a high energy particle. I think they're primarily muons if I remember rightly and we think they come from distant galaxies that they are products of energetic events in very different galaxies and yet they're

[00:12:17] raining down on Earth all the time. How come it affects Voyager and not computers on Earth? Because computers on Earth are shielded by the Earth's magnetic field and its atmosphere and so we are

[00:12:32] not irradiated to the same extent. We do get them though. Cosmic ray events are things that we used to deal with in some of the detectors that are used. In fact, I think we spoke about this

[00:12:46] a little while ago. Maybe we didn't. But the recent aurorae which we saw on Earth on May 10th were also visible on Mars because the subatomic particles from the Sun affected the detectors on

[00:13:00] some of the cameras. We had the same thing actually with cosmic rays which were much more energetic than the rays that come from the Sun. Back in the day when I used to build instruments, one of the problems that we had was these cosmic rays essentially creating little

[00:13:17] bright spots in the images which you had to be careful you didn't mix up with something that you were trying to measure. In fact, one of them we discovered that the window on the front

[00:13:30] of the detector was slightly radioactive so we were getting our own cosmic rays from that. Anyway, the bottom line is protection by the atmosphere. Did NASA have to get people out of retirement to reprogram the 70s computer? Probably. It happens to us a lot.

[00:13:48] Certainly the Australian Astronomical Observatory where I used to be a strongman in charge, that's a long-lived observatory celebrates its 50th anniversary this year. And so some of the original programmers are still around, they're retired, but they are occasionally

[00:14:06] called in when there are problems. So it almost certainly happened with NASA too. How can NASA hear such a weak signal? Well, big dishes. Big E's. Very big E's. That's right. The Deep Space Network website will tell you that the Tidbinbilla and the Goldstone and the

[00:14:23] Madrid stations all have very big detectors, very big radio telescopes that can pick up that really weak signal. Number four of Paddy's questions, will New Horizons ever overtake Voyager given it's smaller and launched on a big rocket? And the answer is no.

[00:14:42] You can very easily find the numbers on the heavens above website. They've got a page on spacecraft leaving the solar system and the first thing you see is that the one that's going fastest is Voyager 1 at 16.933 kilometers per second relative to the sun at present. New Horizons,

[00:15:01] on the other hand, 13.675 kilometers per second, so slower and not as far away. So Voyager 1 is always going to be the most distant object, the most distant human-made object. It will always have that status. Unless it hits something and New Horizons doesn't.

[00:15:23] Well, the odds of, yeah, you never know. It might hit something. My guess is it'll go on forever because space is so big. Yeah, maybe. It might get captured by a... It's further down the street to the chemist, but it's big.

[00:15:39] Yes, that's right. Space is big. That's right. And what was there? Was there another one of Rossi's pages? Is that it? Thank you, Paddy. Fantastic questions. But yeah, well worth asking because Voyager has been in the news

[00:15:55] because they've had some technical issues, but they've sorted them out. So that might be where they drag back the old retired 1970s computer programmers with their tape cartridges and things like that. Yeah, those were the days. It's like, yeah, technology's taken the fun

[00:16:13] out of everything. Back in the day of tape and vinyl, gosh, working in radio was such a joy. These days you push a button and go to sleep for a couple of minutes. It wasn't like that back in the day, I'll tell you now.

[00:16:25] Back in the day of... Back in the day when I was a lad. I'll tell you. I was going to say from my perspective, things are far, far better now than they were. It's only a lot easier until something breaks. Thank you, Paddy. Space nuts.

[00:16:41] Now to our final question, Fred, and this one comes from Jeff. Hi guys. I'm Jeff from the Isle of Wight, down on the UK coast. I love the podcast, by the way, boys.

[00:16:57] My question is if you have a magic pipe, for argument's sake, a metre wide, a diameter, this pipe is totally indestructible, but it doesn't weigh anything. So if you extend it out, say 600 miles out into space, would it suck the atmosphere out?

[00:17:21] I don't think it would, but be interested on your views. Anyway, cheers chaps. Keep it up. You know, I love what if questions, Jeff, and that's a real ripper. So it's an indestructible pipe, so space junk doesn't become a factor.

[00:17:38] It's in the atmosphere, it's on earth, and you shove it up out through the atmosphere into space where the atmosphere is almost nil. It's obviously hollow. Does it suck out our atmosphere and kill us all? No. Which is great relief to all of us. It is rather.

[00:18:02] So the reason why is that the atmosphere in the tube just feels the same gravitational pull as the atmosphere everywhere else. So the pressure at the bottom of the tube is always going to be the same, effectively, as the atmospheric pressure.

[00:18:19] It might vary slightly if the tube is sealed so that you can't get leakage of air in at the bottom, then it won't be subject to quite the same atmospheric pressure changes that the outer atmosphere does.

[00:18:32] But it basically is still the atmosphere and it's still bound by the gravity of the earth. So, yep, it won't leak away. So... It might have any effect at all. You can't even roll Jaffas down.

[00:18:48] And so if you're thinking about checking that out, building a tube from the Isle of Wight up to 600 kilometres, don't worry, it's not going to leak away. It would be a big chimney. Yeah. That would be... Well, yeah, but the smoke could eventually back up, wouldn't it?

[00:19:05] It wouldn't get out into space. If it was a chimney, that's correct. It would do what it does on earth. It would just continue to rise as long as it was warm and then it would just contribute to the general loss of the atmosphere in the tube. Yeah.

[00:19:22] Indeed. All right. So you were right, Jeff. You didn't even need to ask the question. She knew the answer, but that's okay. I love these types of questions, the what-if questions.

[00:19:32] By the way, if you do have a question for us, don't forget to visit our website where you can click on the AMA link and send us a text or audio question or click on the

[00:19:40] Send Us Your Questions button on the right hand side of our homepage where you can leave an audio question. Don't forget to tell us who you are and where you're from. We really do love to know where you're from.

[00:19:51] While you're listening to us on your preferred podcast platform, please leave a review. That'd be doing us a wonderful favour. Apparently, reviews make a huge difference to the state of dark matter in the universe or the dark matter on the internet for that matter. Boom, boom.

[00:20:09] Yeah, we love your reviews. We really appreciate them. And Fred, oh, and thanks to Jeff, Patty and Oliver for contributing to this. And Fred, oh, and thanks to Jeff, Patty and Oliver for contributing today. Keep the questions coming. Fred, we're done for another day. Thank you so much.

[00:20:25] Sounds great, Andrew. And we'll catch up again soon, I hope. I hope so too. Maybe today. Maybe tomorrow. Who knows? Maybe next week. See you then. Fred Watson, astronomer at large and Hugh in the studio doing what Hugh does best. And we don't know what that is.

[00:20:44] And from me, Andrew Dunkley, thanks for your company. Catch you next time on another episode of Space Nuts. Bye-bye.