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Nuclear Space Policies, SETI from the Moon, and the Hubble Tension In this riveting episode of Space Nuts , hosts Andrew Dunkley and Professor Fred Watson delve into a range of fascinating topics that are shaping the future of space exploration. From the Pentagon's new nuclear energy policy for space missions to the exciting potential of searching for extraterrestrial intelligence from the far side of the Moon, this episode is packed with insights that will leave you pondering the cosmos.
Episode Highlights:
- Nuclear Energy in Space: Andrew and Fred Watson discuss the recent directive from the Pentagon to NASA for the development of nuclear power stations in space, exploring the implications for lunar and orbital power supply systems. They examine the benefits and challenges of using nuclear energy in space, addressing public concerns and the potential for collaboration among government agencies.
- SETI from the Far Side of the Moon: The hosts explore the advantages of conducting the Search for Extraterrestrial Intelligence (SETI) from the Moon's far side, where Earthly radio noise is absent. They discuss the capabilities of China's Chang'e 4 mission and its low-frequency radio spectrometer, which is attempting to detect technosignatures that could indicate the presence of alien life.
- The Hubble Tension Debate: Andrew and Fred Watson unpack the ongoing debate surrounding the Hubble constant, highlighting the discrepancies between measurements obtained through different methods. They discuss new research that aims to refine our understanding of the universe's expansion rate and its implications for our grasp of dark matter and dark energy.
For more Space Nuts, including our continuously updating newsfeed and to listen to all our episodes, visit our website. (https://www.spacenutspodcast.com/) Follow us on social media at SpaceNutsPod on Facebook, Instagram, and more. We love engaging with our community, so be sure to drop us a message or comment on your favourite platform.
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Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.
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Episode link: https://play.headliner.app/episode/33024726?utm_source=youtube
00:00:00 --> 00:00:02 Hello again. Thank you for joining us.
00:00:02 --> 00:00:05 This is Space Nuts. My name is Andrew
00:00:05 --> 00:00:06 Dunley. If you've never heard of Space
00:00:06 --> 00:00:08 Nuts, where have you been for the last
00:00:08 --> 00:00:10 10 years? Uh good to have you along if
00:00:10 --> 00:00:12 you're a first timer and everybody else
00:00:12 --> 00:00:16 who's been with us for eons. Uh today on
00:00:16 --> 00:00:19 the show, we will be talking about uh a
00:00:19 --> 00:00:22 a really interesting and some might
00:00:22 --> 00:00:25 think scary development, nuclear space
00:00:25 --> 00:00:27 policies. I don't think they're talking
00:00:27 --> 00:00:29 about, you know, weapons of mass
00:00:29 --> 00:00:31 destruction, but they are talking about
00:00:31 --> 00:00:34 power supply systems. Uh we're also
00:00:34 --> 00:00:36 going to look at SETI from the far side
00:00:36 --> 00:00:38 of the moon because uh that's the best
00:00:38 --> 00:00:41 place to listen for alien civilizations
00:00:41 --> 00:00:44 because well, Earth is very noisy. But
00:00:44 --> 00:00:46 the far side of the moon, you can't hear
00:00:46 --> 00:00:50 a thing except the aliens apparently.
00:00:50 --> 00:00:53 And oh no, the Hubble tension debate is
00:00:53 --> 00:00:56 siming simmering again. We will get into
00:00:56 --> 00:00:59 all of that on this uh this episode of
00:00:59 --> 00:01:00 Space Nuts.
00:01:00 --> 00:01:05 >> 15 seconds. Guidance is internal. 10 9g
00:01:05 --> 00:01:07 Ignition sequence start.
00:01:07 --> 00:01:08 >> Space nuts.
00:01:08 --> 00:01:13 >> 5 4 3 2 1 2 3 4 5 5 4 3 2 1
00:01:13 --> 00:01:14 >> Space Nuts.
00:01:14 --> 00:01:17 >> Astronauts report. It feels good.
00:01:17 --> 00:01:19 >> And joining us to nuke a few stories is
00:01:19 --> 00:01:21 Professor Fred Watson, astronomer at
00:01:21 --> 00:01:24 large. Hello, Fred. Hello, Andrew.
00:01:24 --> 00:01:27 Lovely to uh hear your voice and see
00:01:27 --> 00:01:28 your face.
00:01:28 --> 00:01:30 >> It's my my voice is still a little bit
00:01:30 --> 00:01:33 down like that. I could do an Elvis song
00:01:33 --> 00:01:34 as a backing vocal.
00:01:34 --> 00:01:35 >> You could. Yeah.
00:01:35 --> 00:01:37 >> Yeah. Way on down.
00:01:37 --> 00:01:39 >> Well, we So, at the end of the show, you
00:01:39 --> 00:01:41 definitely need to say thank you very
00:01:41 --> 00:01:42 much.
00:01:42 --> 00:01:43 >> Thank you very much.
00:01:43 --> 00:01:46 >> Uh yeah, it's that's what happens when I
00:01:46 --> 00:01:48 get a cold. My voice just goes down
00:01:48 --> 00:01:50 deep. When I first started in radio, I
00:01:50 --> 00:01:52 did Midnight to Dawns in the days where
00:01:52 --> 00:01:54 they didn't automate it. Everything
00:01:54 --> 00:01:56 Everything was live
00:01:56 --> 00:01:58 >> and around 4 in the morning when I used
00:01:58 --> 00:02:00 to get really really tired, my voice
00:02:00 --> 00:02:05 would just naturally go down there and
00:02:05 --> 00:02:08 and it was really weird because um it
00:02:08 --> 00:02:11 wasn't my natural voice, but um at the
00:02:11 --> 00:02:13 moment it's it's enjoying that part of
00:02:13 --> 00:02:15 the spectrum. So
00:02:15 --> 00:02:17 >> yes, hopefully it'll get better soon. I
00:02:17 --> 00:02:19 don't like the feeling, I must say.
00:02:19 --> 00:02:21 >> No, you wouldn't.
00:02:21 --> 00:02:23 >> Anyway, we battle on, don't we? No point
00:02:23 --> 00:02:24 getting all
00:02:24 --> 00:02:25 >> that's, you know,
00:02:25 --> 00:02:28 >> we do in space nuts. We come rain or
00:02:28 --> 00:02:30 shine or absence or whatever, we keep
00:02:30 --> 00:02:30 going.
00:02:30 --> 00:02:34 >> We do. Speaking of battling on nuclear
00:02:34 --> 00:02:36 energy. Uh
00:02:36 --> 00:02:39 uh this this is a a policy that's just
00:02:39 --> 00:02:41 been announced by the Pentagon and the
00:02:41 --> 00:02:43 Department of Energy and they've kind of
00:02:43 --> 00:02:46 dragged NASA into it. They said, "Hey,
00:02:46 --> 00:02:48 NASA, we want you to build us a couple
00:02:48 --> 00:02:50 of power stations, and they've got to be
00:02:50 --> 00:02:51 nuclear, and they got to be ready by
00:02:51 --> 00:02:53 2028."
00:02:53 --> 00:02:54 How about it?
00:02:54 --> 00:02:57 >> Yeah, that's more or less it. It's a
00:02:58 --> 00:03:02 six-page policy document. Uh, its title
00:03:02 --> 00:03:05 is NSTM-3.
00:03:05 --> 00:03:08 uh which is to direct a parallel and
00:03:08 --> 00:03:11 mutually reinforcing design uh set of
00:03:11 --> 00:03:13 design competitions by NASA and the
00:03:13 --> 00:03:15 defense department to enable and I'm
00:03:15 --> 00:03:17 quoting here to enable near-term
00:03:17 --> 00:03:20 demonstration and use of low to midpower
00:03:20 --> 00:03:22 space reactors in orbit and on the lunar
00:03:22 --> 00:03:25 surface and prepare to deploy high power
00:03:25 --> 00:03:29 reactors in the 2030s. Uh I'm quoting
00:03:29 --> 00:03:32 here from uh uh from people who who are
00:03:32 --> 00:03:34 closely involved with this. For this to
00:03:34 --> 00:03:36 work, it has to be a collaboration
00:03:36 --> 00:03:38 between multiple government agencies.
00:03:38 --> 00:03:40 Well, that's that's a novel idea, isn't
00:03:40 --> 00:03:40 it?
00:03:40 --> 00:03:41 >> Yes.
00:03:41 --> 00:03:43 >> Um, that's the way
00:03:43 --> 00:03:44 >> that'll work.
00:03:44 --> 00:03:45 >> Yeah.
00:03:45 --> 00:03:47 >> That's the way that we do the right R&D
00:03:47 --> 00:03:49 and get the right tools in place for
00:03:49 --> 00:03:51 these events to unfold over the next few
00:03:51 --> 00:03:51 years.
00:03:51 --> 00:03:52 >> Yeah.
00:03:52 --> 00:03:54 >> Yes. So, um, that's right. So the bottom
00:03:54 --> 00:03:56 line is NASA
00:03:56 --> 00:04:01 is directed to start work within 30 days
00:04:01 --> 00:04:03 on a midpower space reactor generating
00:04:03 --> 00:04:06 at least 20 kW of power with a variant
00:04:06 --> 00:04:08 that can operate on the lunar surface.
00:04:08 --> 00:04:10 He calls for the agency to work with
00:04:10 --> 00:04:12 multiple companies on reactor designs,
00:04:12 --> 00:04:14 including for a low power system that
00:04:14 --> 00:04:16 produces as little as 1 kilowatt if
00:04:16 --> 00:04:19 doing so offers lower cost and schedule
00:04:19 --> 00:04:22 risk. This is um it's a White House uh
00:04:22 --> 00:04:24 release that I'm quoting from here. So,
00:04:24 --> 00:04:26 it's uh it's definitely the official
00:04:26 --> 00:04:26 thing.
00:04:26 --> 00:04:29 >> Yeah. Wow. Should we be surprised by
00:04:29 --> 00:04:30 this though?
00:04:30 --> 00:04:32 >> No. No, we shouldn't. I mean, actually,
00:04:32 --> 00:04:35 we did get um was it Jared Isaacman, the
00:04:35 --> 00:04:39 uh the new relatively new head of NASA,
00:04:39 --> 00:04:42 who I think we covered this uh quite a
00:04:42 --> 00:04:45 few months ago, talked about the idea of
00:04:45 --> 00:04:47 uh using a 100 kow nuclear reactor on
00:04:47 --> 00:04:50 the lunar surface. that raises a few
00:04:50 --> 00:04:52 eyebrows. But it looks as though this is
00:04:52 --> 00:04:56 the first step in in um in expediting
00:04:56 --> 00:04:59 that to start small, maybe even the
00:04:59 --> 00:05:01 smallest 1 kilowatt. It'll run an
00:05:01 --> 00:05:04 electric fire uh and uh and um keep
00:05:04 --> 00:05:08 going upwards. Uh there's a interesting
00:05:08 --> 00:05:11 uh disparity in the sort of urgency of
00:05:11 --> 00:05:14 this though because um the next
00:05:14 --> 00:05:15 paragraph of the White House release
00:05:15 --> 00:05:17 says the policy calls on the defense
00:05:17 --> 00:05:20 department to provide a briefing to the
00:05:20 --> 00:05:23 White House in 90 days on potential uses
00:05:23 --> 00:05:25 and payloads for space nuclear systems
00:05:26 --> 00:05:27 of varying power levels. The Pentagon
00:05:28 --> 00:05:30 will in the first year of the policy use
00:05:30 --> 00:05:32 its space nuclear funding to support
00:05:32 --> 00:05:34 NASA's efforts, then conduct its own
00:05:34 --> 00:05:36 competition for space nuclear power
00:05:36 --> 00:05:38 systems. I get the feeling here that
00:05:38 --> 00:05:40 there's going to be too many fingers in
00:05:40 --> 00:05:43 the pie and too many people deciding
00:05:43 --> 00:05:44 which companies are going to get the,
00:05:44 --> 00:05:46 you know, going to get the contracts to
00:05:46 --> 00:05:48 do this.
00:05:48 --> 00:05:51 the the options for nuclear power these
00:05:51 --> 00:05:54 days are so much more
00:05:54 --> 00:05:57 uh available and and simple like you can
00:05:58 --> 00:06:00 make very small nuclear power stations
00:06:00 --> 00:06:03 now you you can you can build one that's
00:06:03 --> 00:06:05 that's small enough just to service a
00:06:06 --> 00:06:08 town these days you don't need these big
00:06:08 --> 00:06:10 complex
00:06:10 --> 00:06:13 >> setups anymore so it it probably is the
00:06:13 --> 00:06:15 logical way to go even though when you
00:06:15 --> 00:06:17 say the word nuclear everybody sort runs
00:06:17 --> 00:06:19 for the hills. Not that that would save
00:06:19 --> 00:06:23 them, but um it's not as big and scary
00:06:23 --> 00:06:25 as people
00:06:25 --> 00:06:28 envvisage, but um it it's it's got bad
00:06:28 --> 00:06:30 press for a long long time. So whenever
00:06:30 --> 00:06:32 you talk about nuclear power station or
00:06:32 --> 00:06:35 look what happened in Australia um we're
00:06:35 --> 00:06:38 so scared of it, we've never done it.
00:06:38 --> 00:06:40 And people think of three mile three
00:06:40 --> 00:06:43 mile island and churn bill
00:06:43 --> 00:06:46 >> uh and uh yes and the bottom line is
00:06:46 --> 00:06:48 that if things go wrong you have a very
00:06:48 --> 00:06:51 big environmental problem uh and that
00:06:51 --> 00:06:54 would look at Fukushima yeah with the um
00:06:54 --> 00:06:56 earthquake and the t and the and the
00:06:56 --> 00:06:58 tsunami. Yeah,
00:06:58 --> 00:06:59 >> that's a mess.
00:07:00 --> 00:07:05 >> Yes. So uh it is scary I think. Um
00:07:05 --> 00:07:07 but but well so I grew up in a country
00:07:07 --> 00:07:10 that uh pioneered nuclear power with the
00:07:10 --> 00:07:13 US and there are several nuclear power
00:07:13 --> 00:07:15 stations. Uh I used to live not very far
00:07:15 --> 00:07:19 from one actually at Torres in Scotland.
00:07:19 --> 00:07:21 >> Is it is that right? Yes. I think it's
00:07:21 --> 00:07:25 Torres. Uh and um look it everybody just
00:07:25 --> 00:07:27 regarded it as a normal power station.
00:07:27 --> 00:07:30 It was very much a low-key thing. Uh and
00:07:30 --> 00:07:34 and you you see statistics like there's
00:07:34 --> 00:07:37 more radiation comes from the natural
00:07:37 --> 00:07:39 emissions from rocks in the UK. If you
00:07:40 --> 00:07:41 go down to Cornwall, the rocks are
00:07:41 --> 00:07:43 basically radioactive there.
00:07:43 --> 00:07:44 >> Oh wow.
00:07:44 --> 00:07:46 >> There's radon in the atmosphere. Um but
00:07:46 --> 00:07:48 it's at a level that humans can
00:07:48 --> 00:07:51 tolerate. Humans have been tolerating it
00:07:51 --> 00:07:53 for hundreds of thousands of years. And
00:07:53 --> 00:07:56 uh that's Yeah. You're exposed to
00:07:56 --> 00:07:58 radiation every time you walk outside.
00:07:58 --> 00:08:01 >> Well, that's right. you are. Yes. So,
00:08:01 --> 00:08:03 um, so it it it's got to be treated with
00:08:04 --> 00:08:07 respect. Um, I I I think what freaks
00:08:07 --> 00:08:09 people out though as well is the idea of
00:08:09 --> 00:08:12 sticking a nuclear reactor on top of a
00:08:12 --> 00:08:15 rocket and then sending it into space.
00:08:15 --> 00:08:18 And there was an accident uh with a so
00:08:18 --> 00:08:21 just stepping back NASA has used their
00:08:21 --> 00:08:26 RTGS radioisotope thermal gener
00:08:26 --> 00:08:27 thermmoelectric generators. I think
00:08:27 --> 00:08:30 that's what it stands for. Uh on several
00:08:30 --> 00:08:32 spacecraft including the two Voyagers. I
00:08:32 --> 00:08:34 think the Pioneers have got it as well.
00:08:34 --> 00:08:39 Um the um Curiosity and
00:08:39 --> 00:08:42 um Perseverance both have RTG power
00:08:42 --> 00:08:46 supplies. Uh so so that's well you know
00:08:46 --> 00:08:49 a well trodden path but there was an
00:08:49 --> 00:08:50 accident. I think it might have been in
00:08:50 --> 00:08:52 the 80s with a spacecraft that was
00:08:52 --> 00:08:54 launched with something like an RTG on
00:08:54 --> 00:08:58 board and it did uh it went wrong. I
00:08:58 --> 00:09:00 can't remember the details, but I think
00:09:00 --> 00:09:02 it was Canada that took the the punch
00:09:02 --> 00:09:05 and there was a lot of radioactive
00:09:05 --> 00:09:09 debris that got spread over very very uh
00:09:09 --> 00:09:13 sparsely populated regions of Canada.
00:09:13 --> 00:09:14 >> Literal fallout.
00:09:14 --> 00:09:16 >> Yes, that's right. Yes, exactly. Falls
00:09:16 --> 00:09:18 out the sky. If I remember rightly, I'm
00:09:18 --> 00:09:20 I'm digging up things from the past
00:09:20 --> 00:09:21 year, but I think that's the case. And
00:09:21 --> 00:09:24 that that clearly freaks people out. If
00:09:24 --> 00:09:26 you've got a launch that doesn't work,
00:09:26 --> 00:09:29 uh what's going to happen? I imagine so.
00:09:29 --> 00:09:31 But, uh it certainly does ramp up the
00:09:31 --> 00:09:34 space race between the US and China. And
00:09:34 --> 00:09:35 you know, China's probably going to fall
00:09:35 --> 00:09:37 a bit behind here because I think they
00:09:37 --> 00:09:39 were trying to set up a coal fired power
00:09:39 --> 00:09:42 station on the moon. You know, it um
00:09:42 --> 00:09:44 >> might might slow them down a bit.
00:09:44 --> 00:09:46 >> Yeah, China's doing pretty well. They
00:09:46 --> 00:09:47 are doing
00:09:47 --> 00:09:49 >> sustainability. Yeah.
00:09:49 --> 00:09:49 >> Yeah, they are.
00:09:49 --> 00:09:51 >> But yeah, they do use a lot of coal
00:09:51 --> 00:09:52 still. Yeah,
00:09:52 --> 00:09:54 >> they do. They do. So, this is probably
00:09:54 --> 00:09:57 going to happen. And what other option
00:09:57 --> 00:09:59 would there be? That's the thing. I
00:09:59 --> 00:10:00 mean, some people will say, "No, put up
00:10:00 --> 00:10:04 solar energy systems, but um nuclear is
00:10:04 --> 00:10:07 probably a a much more efficient way of
00:10:07 --> 00:10:08 doing it."
00:10:08 --> 00:10:10 >> Yeah. Well, for a start, you've got the
00:10:10 --> 00:10:12 baseline load. You don't not worried
00:10:12 --> 00:10:14 about where the sun is in the sky.
00:10:14 --> 00:10:17 Correct. The idea of being at the south
00:10:17 --> 00:10:20 pole of the moon which is where the
00:10:20 --> 00:10:23 focus is in terms of uh our exploration
00:10:23 --> 00:10:27 of the moon uh is it it puts a different
00:10:27 --> 00:10:29 slant on it because it means that you
00:10:29 --> 00:10:32 are looking at a very low sun altitude
00:10:32 --> 00:10:35 in the sky. Uh the sun's coming in
00:10:35 --> 00:10:36 nearly horizontally the sunlight. Now
00:10:36 --> 00:10:40 that's not uh as bad a thing on the moon
00:10:40 --> 00:10:42 as it would be on the earth. The Earth,
00:10:42 --> 00:10:44 as the sun gets lower, it's going
00:10:44 --> 00:10:45 through a thicker and thicker layer of
00:10:45 --> 00:10:47 atmosphere. So, it's power is
00:10:47 --> 00:10:48 attenuated.
00:10:48 --> 00:10:50 >> On the moon, that doesn't happen because
00:10:50 --> 00:10:52 there ain't no atmosphere. But, it does
00:10:52 --> 00:10:55 bring challenges for your solar panels.
00:10:55 --> 00:10:56 You know, you've got to build arrays
00:10:56 --> 00:10:59 that are almost vertical. And if you're
00:10:59 --> 00:11:01 looking for a big structure, uh then
00:11:01 --> 00:11:04 it's uh it it becomes different slightly
00:11:04 --> 00:11:07 different engineering um issue. Plus,
00:11:07 --> 00:11:08 you've got to take all that stuff up
00:11:08 --> 00:11:11 there as well. You know, going up to the
00:11:11 --> 00:11:13 moon with arrays of solar panels in the
00:11:13 --> 00:11:15 spacecraft might not leave room for much
00:11:15 --> 00:11:17 else. Whereas a nuclear reactor of the
00:11:17 --> 00:11:18 kind that people are talking about will
00:11:18 --> 00:11:21 be relatively compact. I mean, the the
00:11:21 --> 00:11:25 RTG devices are I think it's is it 13 kg
00:11:25 --> 00:11:29 of uh of plutonium that they have in
00:11:29 --> 00:11:32 them and they're about the size of a you
00:11:32 --> 00:11:35 know a tea or something like that or
00:11:35 --> 00:11:36 >> a drinks. Yeah.
00:11:36 --> 00:11:39 >> Yeah. It it's it's much simpler than it
00:11:39 --> 00:11:42 was 20, 30, 40, 50 years ago.
00:11:42 --> 00:11:43 >> And of course, they're talking not only
00:11:43 --> 00:11:46 about the moon, but uh people on Mars,
00:11:46 --> 00:11:48 so they'll need power as well. Uh I know
00:11:48 --> 00:11:50 in the movie The Martian, they used
00:11:50 --> 00:11:52 solar panels, but Mars is bit further
00:11:52 --> 00:11:54 away, so the solar panels probably
00:11:54 --> 00:11:55 wouldn't be as efficient.
00:11:55 --> 00:11:56 >> Exactly.
00:11:56 --> 00:11:59 >> Uh nuclear power makes makes perfect
00:11:59 --> 00:12:02 sense. Although you know solar solar
00:12:02 --> 00:12:07 energy is quite um well used in space
00:12:07 --> 00:12:09 too used it.
00:12:09 --> 00:12:12 >> Um that's correct. Yes. Uh and um you
00:12:12 --> 00:12:14 know thinking of the different
00:12:14 --> 00:12:15 spacecraft the one that's got perhaps
00:12:15 --> 00:12:17 the most spectacular solar panels is the
00:12:17 --> 00:12:20 Lucy spacecraft which is on its way to
00:12:20 --> 00:12:23 the Trojan asteroids. Uh and that's got
00:12:23 --> 00:12:26 solar panels which are huge and that's
00:12:26 --> 00:12:28 because you're going out to the asteroid
00:12:28 --> 00:12:30 belt and beyond. actually going to the
00:12:30 --> 00:12:31 orbit of Jupiter which is where the
00:12:31 --> 00:12:34 Trojan asteroids hang out. Uh so you
00:12:34 --> 00:12:36 need big solar panels to collect all the
00:12:36 --> 00:12:37 energy.
00:12:37 --> 00:12:38 >> Yeah. The other problem with solar
00:12:38 --> 00:12:41 panels on Mars would be dust because
00:12:41 --> 00:12:44 >> it's it's a pretty grubby place.
00:12:44 --> 00:12:46 >> Yeah. That's what um probably brought an
00:12:46 --> 00:12:49 end to so Spirit and Opportunity both
00:12:49 --> 00:12:52 had solar panels. Uh and they there were
00:12:52 --> 00:12:54 certainly times when the amount of dust
00:12:54 --> 00:12:57 was stopping the power generation and
00:12:57 --> 00:13:00 that was cleared by uh willy-willies as
00:13:00 --> 00:13:02 they're called
00:13:02 --> 00:13:03 the
00:13:03 --> 00:13:05 >> dust devils that's right on Mars. Yeah.
00:13:05 --> 00:13:08 >> Fascinating. All right. So the um the
00:13:08 --> 00:13:10 directive has been put to NASA to start
00:13:10 --> 00:13:11 working on this.
00:13:12 --> 00:13:14 >> Uh and it comes from the White House. So
00:13:14 --> 00:13:16 um it's all systems go and they hope to
00:13:16 --> 00:13:19 have something operational as soon as
00:13:19 --> 00:13:22 2028. So they're not mucking around. In
00:13:22 --> 00:13:23 fact, I think NASA after this was
00:13:23 --> 00:13:25 released were given one month to get
00:13:25 --> 00:13:26 started.
00:13:26 --> 00:13:26 >> So,
00:13:26 --> 00:13:28 >> uh, that's exactly right. That's the 30
00:13:28 --> 00:13:29 days that I mentioned earlier.
00:13:29 --> 00:13:30 >> No mucking around.
00:13:30 --> 00:13:31 >> Get going.
00:13:31 --> 00:13:33 >> Yep. Uh, you can read all about it at
00:13:33 --> 00:13:36 spacnews.com.
00:13:36 --> 00:13:38 This is Space Nuts with Andrew Dunley
00:13:38 --> 00:13:43 and Professor Fred Watson.
00:13:43 --> 00:13:45 >> G. And I feel
00:13:45 --> 00:13:46 >> space nuts.
00:13:46 --> 00:13:47 >> Well, we mentioned the moon. We'll stick
00:13:48 --> 00:13:50 with the moon. This story though has
00:13:50 --> 00:13:52 nothing to do with people on the moon.
00:13:52 --> 00:13:54 It's got uh everything to do with people
00:13:54 --> 00:13:57 that are not on Earth or the moon or
00:13:57 --> 00:13:59 Mars for that matter. They uh they're
00:13:59 --> 00:14:01 out there somewhere. We're looking for
00:14:01 --> 00:14:03 them. We're talking about the search for
00:14:03 --> 00:14:06 extraterrestrial intelligence and the
00:14:06 --> 00:14:08 dark side of the moon, the far side of
00:14:08 --> 00:14:11 the moon is uh the best place to start
00:14:11 --> 00:14:13 looking.
00:14:13 --> 00:14:14 >> Uh that's right. So, we've been looking
00:14:14 --> 00:14:18 for this for 60 years. um and
00:14:18 --> 00:14:22 >> and using uh groundbased antennas here
00:14:22 --> 00:14:26 on planet earth uh which are very very
00:14:26 --> 00:14:29 capable um when once the square
00:14:29 --> 00:14:31 kilometer array observatory comes on
00:14:31 --> 00:14:33 stream towards the end of the decade uh
00:14:34 --> 00:14:37 we'll have the finest most capable radio
00:14:37 --> 00:14:41 telescope in the world uh which will not
00:14:41 --> 00:14:44 directly engage with SETI programs but
00:14:44 --> 00:14:45 it will
00:14:45 --> 00:14:48 uh have the sensitivity to detect well
00:14:48 --> 00:14:50 the thing that my colleagues tell me is
00:14:50 --> 00:14:52 it'll detect an airport radar at 50
00:14:52 --> 00:14:53 light years.
00:14:53 --> 00:14:53 >> Yeah.
00:14:54 --> 00:14:57 >> Uh so that's the kind of sensitivity uh
00:14:57 --> 00:15:00 that you're talking about. Um, but the
00:15:00 --> 00:15:02 main problem with groundbased with
00:15:02 --> 00:15:05 earthbased uh radio telescopes is that
00:15:05 --> 00:15:07 they're compromised by all the the
00:15:07 --> 00:15:10 cacophony of radio signals that
00:15:10 --> 00:15:12 surrounds us from your mobile phones,
00:15:12 --> 00:15:15 from broadcasts, from people like you
00:15:15 --> 00:15:17 and me doing this, going out into the
00:15:17 --> 00:15:18 ether,
00:15:18 --> 00:15:19 >> Wi-Fi routers,
00:15:19 --> 00:15:22 >> Wi-Fi, the whole thing, microwave ovens,
00:15:22 --> 00:15:24 it all provides this noisy radio
00:15:24 --> 00:15:27 background. And that's not getting any
00:15:27 --> 00:15:29 better with the um satellite mega
00:15:29 --> 00:15:31 constellations.
00:15:31 --> 00:15:35 I was in a meeting yesterday where which
00:15:35 --> 00:15:37 for it's a meeting of the um
00:15:37 --> 00:15:39 international astronomical union center
00:15:39 --> 00:15:42 for the protection of the dark and quiet
00:15:42 --> 00:15:45 sky from satellite interference. Uh and
00:15:45 --> 00:15:47 it was um you know one of the things
00:15:47 --> 00:15:50 that's raising anxiety is the idea of uh
00:15:50 --> 00:15:53 Elon Musk's million satellites for for
00:15:53 --> 00:15:57 um orbital data u orbital data centers
00:15:57 --> 00:16:00 and this mirror in the sky idea sunlight
00:16:00 --> 00:16:01 on demand that also has a million
00:16:01 --> 00:16:04 satellites with mirrors on it. That's
00:16:04 --> 00:16:05 that's more for the optical astronomers
00:16:05 --> 00:16:09 but it's all a concern. uh and it's it
00:16:09 --> 00:16:11 it basically is eroding our capability
00:16:11 --> 00:16:14 slowly but surely to detect uh faint
00:16:14 --> 00:16:17 extraterrestrial signals.
00:16:17 --> 00:16:21 Uh so that brings us to currently
00:16:21 --> 00:16:24 possibly the best place to do this sort
00:16:24 --> 00:16:27 of thing from which is the far side of
00:16:27 --> 00:16:33 the moon. Uh and um uh we have one uh
00:16:33 --> 00:16:36 spacecraft by we I mean humankind have
00:16:36 --> 00:16:38 one spacecraft on the far side of the
00:16:38 --> 00:16:42 moon. Uh it is China's Chang 4 uh which
00:16:42 --> 00:16:44 soft landed on the far side of the moon
00:16:44 --> 00:16:47 back in 2019. Can you believe it? It's
00:16:47 --> 00:16:49 been there.
00:16:49 --> 00:16:51 >> Uh this is seven years. It's quite
00:16:51 --> 00:16:56 extraordinary. Um but uh now that um
00:16:56 --> 00:16:59 spacecraft was not set up uh
00:16:59 --> 00:17:03 specifically for uh for looking for um
00:17:03 --> 00:17:05 SETI search for extraterrestrial
00:17:05 --> 00:17:08 intelligence but it's got a low
00:17:08 --> 00:17:12 frequency radio spectrometer on board uh
00:17:12 --> 00:17:15 that actually has been used to conduct
00:17:15 --> 00:17:17 the first ever SETI search from the
00:17:17 --> 00:17:22 lunar far side. Um and so the the goal
00:17:22 --> 00:17:26 uh the idea is to use that equipment
00:17:26 --> 00:17:29 which is designed to do natural sciences
00:17:29 --> 00:17:34 but to look for um those uh techno
00:17:34 --> 00:17:36 signatures uh technomarkers they're
00:17:36 --> 00:17:39 sometimes called uh which might suggest
00:17:39 --> 00:17:41 that you're getting a signal from an
00:17:41 --> 00:17:44 artificially generated source. And what
00:17:44 --> 00:17:47 you're really looking for are uh
00:17:47 --> 00:17:49 periodic
00:17:49 --> 00:17:52 um bursts of radiation with perhaps
00:17:52 --> 00:17:54 regular intervals
00:17:54 --> 00:17:57 um that are not easily explained
00:17:57 --> 00:18:00 >> by natural processes. And you've got got
00:18:00 --> 00:18:04 to think back to Joselyn Bell and her
00:18:04 --> 00:18:06 discovery of the first pulsar because
00:18:06 --> 00:18:09 that's what she saw. um narrow band um
00:18:09 --> 00:18:14 sorry uh narrow band in time signatures
00:18:14 --> 00:18:17 uh or bursts of radiation which we now
00:18:17 --> 00:18:18 know is the pulsar the kind of
00:18:18 --> 00:18:20 lighthouse beam of radiation from the
00:18:20 --> 00:18:22 pulsar sweeping round and passing the
00:18:22 --> 00:18:25 earth. Um she didn't know that then so
00:18:25 --> 00:18:28 she wrote little green men in her uh in
00:18:28 --> 00:18:31 on her chart record of very very famous
00:18:31 --> 00:18:35 words. Um so that's what basically uh
00:18:35 --> 00:18:39 the uh Changa um low frequency radio
00:18:39 --> 00:18:41 spectrometer has been looking for. Uh
00:18:41 --> 00:18:44 and it's things that um you know that
00:18:44 --> 00:18:46 speak of an artificially generated
00:18:46 --> 00:18:50 source. And so um what's what they've
00:18:50 --> 00:18:53 done uh the scientists working on this
00:18:53 --> 00:18:56 uh basically they built an algorithm
00:18:56 --> 00:18:59 uh that uh uh troll through the data
00:18:59 --> 00:19:03 looking for anything that might be
00:19:03 --> 00:19:07 artificial with no credible candidates
00:19:07 --> 00:19:10 revealed. Uh nothing that couldn't be
00:19:10 --> 00:19:13 explained either by you know natural
00:19:13 --> 00:19:18 phenomena or by instrument uh issues. Um
00:19:18 --> 00:19:20 there's a nice comment though from
00:19:20 --> 00:19:25 fizz.org who is carrying this story. Uh
00:19:25 --> 00:19:27 this is I'll quote this. This is not a
00:19:27 --> 00:19:29 failure. It is a beginning. As Carl Sean
00:19:29 --> 00:19:33 once put it, absence of evidence is not
00:19:33 --> 00:19:35 evidence of absence. Brilliant.
00:19:35 --> 00:19:36 >> Really good point.
00:19:36 --> 00:19:38 >> I I got I had a lot of time for Carl
00:19:38 --> 00:19:41 Sean, very wise man and um yeah, he uh
00:19:41 --> 00:19:43 he did a lot for astronomy
00:19:43 --> 00:19:46 >> during his time. But um that's a valid
00:19:46 --> 00:19:48 point and and I suppose you and I have
00:19:48 --> 00:19:50 spoken about it in the past. The big
00:19:50 --> 00:19:53 problem is distance. There might there
00:19:53 --> 00:19:55 might be civilizations out there that
00:19:55 --> 00:19:57 are advanced and capable of
00:19:57 --> 00:19:59 communication, but they're so far away
00:19:59 --> 00:20:01 we will never hear from them.
00:20:01 --> 00:20:05 >> Maybe that Yeah. Um that's right. Uh and
00:20:05 --> 00:20:07 you know, and time is the other issue.
00:20:07 --> 00:20:09 It's a needle in a hay stack both in
00:20:09 --> 00:20:11 distance and in time because you've got
00:20:11 --> 00:20:13 to hit your civilization just at the
00:20:13 --> 00:20:14 right time.
00:20:14 --> 00:20:15 >> Yes.
00:20:15 --> 00:20:18 >> Uh when they are technologically enough
00:20:18 --> 00:20:20 to have airport radar, for example, uh
00:20:20 --> 00:20:22 but haven't wiped themselves out because
00:20:22 --> 00:20:24 of the loonies that they've generated.
00:20:24 --> 00:20:26 You're more you're more likely to get a
00:20:26 --> 00:20:29 um a tick tock of some kid doing a
00:20:29 --> 00:20:32 stupid rap song. That's probably that's
00:20:32 --> 00:20:35 what you'll get from from an
00:20:35 --> 00:20:38 extraterrestrial intelligence. Um what
00:20:38 --> 00:20:42 what I wonder is with the far side of
00:20:42 --> 00:20:44 the moon, yes, it's radio silent, but
00:20:44 --> 00:20:47 does it cover enough of the spectrum of
00:20:47 --> 00:20:50 the universe to to pick up something or
00:20:50 --> 00:20:52 is or is it fairly narrow in its its
00:20:52 --> 00:20:53 scope?
00:20:53 --> 00:20:55 >> Uh do you mean uh in terms of direction
00:20:55 --> 00:20:56 or
00:20:56 --> 00:20:58 >> Yeah. being able to pick something up?
00:20:58 --> 00:21:00 Is it got like a wide array? I mean the
00:21:00 --> 00:21:03 far side of the moon um you know if you
00:21:03 --> 00:21:05 plunk something on the equator of the
00:21:06 --> 00:21:09 moon on the far side over a month you
00:21:09 --> 00:21:11 cover the entire sky. No
00:21:11 --> 00:21:15 >> uh if your Yeah. If your um if your uh
00:21:15 --> 00:21:18 equipment is broadband enough and all
00:21:18 --> 00:21:20 the seti stuff is it's got a very wide
00:21:20 --> 00:21:22 range of spectral of frequencies.
00:21:22 --> 00:21:25 Although they do tend to to concentrate
00:21:25 --> 00:21:29 on uh what we call the 21 cm line. This
00:21:29 --> 00:21:31 is the frequency the specific frequency
00:21:32 --> 00:21:34 that's radiated by cold hydrogen.
00:21:34 --> 00:21:37 >> Uh and they do tend to concentrate on
00:21:37 --> 00:21:39 that because everybody in the universe
00:21:39 --> 00:21:43 will be aware of that 21 cm uh uh
00:21:43 --> 00:21:45 wavelength because that's called
00:21:45 --> 00:21:48 hydrogen which is the same everywhere.
00:21:48 --> 00:21:51 >> Yeah, makes sense. All right. Uh
00:21:51 --> 00:21:54 fascinating story. Um nothing yet but
00:21:54 --> 00:21:56 that doesn't mean that doesn't mean
00:21:56 --> 00:21:58 it'll always be nothing. So
00:21:58 --> 00:22:01 >> it's not um evidence of absence. That's
00:22:01 --> 00:22:01 right.
00:22:02 --> 00:22:04 >> Exactly. You can read all about it as
00:22:04 --> 00:22:08 Fred said at the fizz physf.org
00:22:08 --> 00:22:10 website. This is Space Nuts. Andrew
00:22:10 --> 00:22:15 Dunley here with Professor Fred Watson.
00:22:15 --> 00:22:17 >> Okay, we checked all four systems and
00:22:17 --> 00:22:18 with the
00:22:18 --> 00:22:19 >> Space Nuts.
00:22:19 --> 00:22:22 >> Our final story, Fred, uh brings us back
00:22:22 --> 00:22:25 to that old debate about the Hubble
00:22:25 --> 00:22:28 tension. Now, the Hubble tension is
00:22:28 --> 00:22:30 measured in two different ways, and they
00:22:30 --> 00:22:32 come up with two different answers, and
00:22:32 --> 00:22:35 that's troubled people for a while.
00:22:35 --> 00:22:36 Although, we did a story not so long ago
00:22:36 --> 00:22:39 that suggested, hang on a minute, the
00:22:39 --> 00:22:41 differences aren't that significant. So,
00:22:41 --> 00:22:44 they're probably both right if you allow
00:22:44 --> 00:22:47 for the u you know, the the variables.
00:22:47 --> 00:22:49 But this story is saying, "Hang on a
00:22:49 --> 00:22:52 minute. We we think there's a better
00:22:52 --> 00:22:53 way."
00:22:53 --> 00:22:57 >> Yes, that's right. uh in exactly that
00:22:57 --> 00:23:00 it's all about so le let's just uh
00:23:00 --> 00:23:03 backtrack what is the Hubble tension uh
00:23:04 --> 00:23:07 so the expansion rate of the universe
00:23:07 --> 00:23:10 basically is a number that we was first
00:23:10 --> 00:23:13 measured by Edwin Hubble back in 1929
00:23:14 --> 00:23:15 um he got the wrong answer because he
00:23:15 --> 00:23:17 was only looking at a very small number
00:23:17 --> 00:23:19 of galaxies but it it comes about
00:23:19 --> 00:23:23 because as you look at galaxies
00:23:23 --> 00:23:25 in the wider universe
00:23:25 --> 00:23:29 uh they get um their velocity away from
00:23:29 --> 00:23:32 us is bigger the further away they are
00:23:32 --> 00:23:34 and that comes about when you've got a
00:23:34 --> 00:23:36 universe that's expanding. That's the
00:23:36 --> 00:23:38 natural assumption and we've believed
00:23:38 --> 00:23:43 that ever since. Yeah. Excuse me. So, so
00:23:43 --> 00:23:44 um got a bit of Hubble tension in my
00:23:44 --> 00:23:47 chest there. Um so that's how it's
00:23:47 --> 00:23:50 normally measure measured the Hubble
00:23:50 --> 00:23:52 constant
00:23:52 --> 00:23:55 this number which is in slightly bizarre
00:23:55 --> 00:23:58 units. It's in mega par kilometers/s per
00:23:58 --> 00:24:02 mega par sec. Kilometers/s is the
00:24:02 --> 00:24:05 recession speed of a galaxy. A mega parc
00:24:05 --> 00:24:09 is uh is it 3.26 I can never remember
00:24:09 --> 00:24:12 the name. Million light years. Uh it's
00:24:12 --> 00:24:14 the it's the units that astronomers use
00:24:14 --> 00:24:17 for measuring distance parex and it's a
00:24:17 --> 00:24:21 million parex. So um kilometers/s per
00:24:21 --> 00:24:24 mega parc tells you how the velocity of
00:24:24 --> 00:24:27 a g galaxy increases with distance and
00:24:27 --> 00:24:29 that's the result of the expansion of
00:24:29 --> 00:24:31 the universe. So the hub constant tells
00:24:32 --> 00:24:34 you how fast the universe is expanding.
00:24:34 --> 00:24:35 Now,
00:24:35 --> 00:24:39 >> now you can you the normal way of doing
00:24:39 --> 00:24:41 this is uh and it's actually why the
00:24:41 --> 00:24:44 Hubble telescope was created and why it
00:24:44 --> 00:24:47 got its name. Uh we excuse me. We
00:24:47 --> 00:24:49 measure the brightness.
00:24:49 --> 00:24:51 Sorry, I've got my got my tension back
00:24:51 --> 00:24:53 there.
00:24:53 --> 00:24:55 If you want to cut this bit out, Hugh,
00:24:55 --> 00:24:58 you're more than welcome to.
00:24:58 --> 00:25:02 Um it's it's fine now. uh the uh the the
00:25:02 --> 00:25:05 tension comes about. So no, let me step
00:25:05 --> 00:25:08 back again. The uh measure the way it's
00:25:08 --> 00:25:10 measured is you build up a sort of
00:25:10 --> 00:25:12 distance scale ladder. So the direct
00:25:12 --> 00:25:15 measurement of star distances in outer
00:25:15 --> 00:25:18 space comes about by the parallax
00:25:18 --> 00:25:20 method. As the earth goes around the
00:25:20 --> 00:25:23 sun, we see stars uh apparently changing
00:25:23 --> 00:25:26 their position with relative to very
00:25:26 --> 00:25:28 distant background stars. And that
00:25:28 --> 00:25:30 change in position you can measure uh
00:25:30 --> 00:25:33 and in fact it's that that gives the
00:25:33 --> 00:25:35 parseek its name. It's a parallax of one
00:25:35 --> 00:25:38 arcsec is what it's short for. And so
00:25:38 --> 00:25:41 that's a direct geometrical way of
00:25:41 --> 00:25:43 measuring the distance to certain stars.
00:25:43 --> 00:25:45 If you can do that to stars whose
00:25:45 --> 00:25:48 intrinsic brightness you know and these
00:25:48 --> 00:25:50 are typically sephied variable stars
00:25:50 --> 00:25:52 then you can extend it because you know
00:25:52 --> 00:25:54 their brightness uh their intrinsic
00:25:54 --> 00:25:56 brightness how much uh light they
00:25:56 --> 00:25:59 radiate then you can look at how faint
00:25:59 --> 00:26:01 they are further and further on um and
00:26:01 --> 00:26:03 that's the that's how we started off
00:26:03 --> 00:26:08 because Hubble um measured um in fact in
00:26:08 --> 00:26:11 1923 used these variable stars to
00:26:11 --> 00:26:12 measure the distance of the Andromeda
00:26:12 --> 00:26:14 galaxy. Once again, he got it a bit
00:26:14 --> 00:26:17 wrong by today's standards, but uh that
00:26:17 --> 00:26:18 was when we realized that galaxies
00:26:18 --> 00:26:20 weren't little things frutling around in
00:26:20 --> 00:26:23 our own milky way. They are very distant
00:26:23 --> 00:26:26 objects. So that's the basic process and
00:26:26 --> 00:26:29 that has now been uh basically
00:26:29 --> 00:26:33 elaborated by additional things which
00:26:33 --> 00:26:36 involve supernovi, the exploding stars,
00:26:36 --> 00:26:39 all sorts of other uh cosmic phenomena.
00:26:39 --> 00:26:42 And that's the basis of what this story
00:26:42 --> 00:26:45 is about because
00:26:45 --> 00:26:49 uh that technology has now been
00:26:49 --> 00:26:53 absolutely refined to the nth degree uh
00:26:53 --> 00:26:57 by the scientists who are uh who are u
00:26:57 --> 00:27:00 uh basically reporting this work. Uh
00:27:00 --> 00:27:02 it's a study in astronomy and
00:27:02 --> 00:27:04 astrophysics one of the leading journals
00:27:04 --> 00:27:07 actually a European journal. uh and the
00:27:07 --> 00:27:10 these scientists have spent a lot of
00:27:10 --> 00:27:14 time getting uh the answer right from
00:27:14 --> 00:27:15 this method what we call the distance
00:27:16 --> 00:27:19 ladder or the distance scale by invoking
00:27:19 --> 00:27:23 objects of all kinds and so they have
00:27:23 --> 00:27:24 produced a number for the Hubble
00:27:24 --> 00:27:28 constant which has a very very small
00:27:28 --> 00:27:33 error in fact they quote it as 7350
00:27:33 --> 00:27:37 kilometers/s per megap par sec plus or
00:27:37 --> 00:27:38 minus.0
00:27:38 --> 00:27:41 sorry 0.81
00:27:41 --> 00:27:44 kilometers/s per mega par sec. So
00:27:44 --> 00:27:46 they're talking about something that's
00:27:46 --> 00:27:49 either somewhere between 72.0 and 74
00:27:49 --> 00:27:54 sorry 72.5 and 74.5 thereabouts which is
00:27:54 --> 00:27:58 a very very tight uh estimate of this
00:27:58 --> 00:27:59 velocity.
00:27:59 --> 00:28:02 Uh so what's the tension about
00:28:02 --> 00:28:05 >> until somebody debunks them?
00:28:05 --> 00:28:08 >> Yeah. Uh it well it's true. Um I do
00:28:08 --> 00:28:11 remember um back in the 70s and I've
00:28:11 --> 00:28:13 told you this before, Andrew, there were
00:28:13 --> 00:28:16 two schools of thought. Both offering
00:28:16 --> 00:28:18 measurements with very tight error
00:28:18 --> 00:28:20 limits. One of which said that the
00:28:20 --> 00:28:22 number was 50 and the other which said
00:28:22 --> 00:28:24 the number was 100. Yeah. And lo and
00:28:24 --> 00:28:25 behold, when we when the Hubble
00:28:25 --> 00:28:27 telescope gave us the right answer, it
00:28:27 --> 00:28:28 was basically at the average of those
00:28:28 --> 00:28:31 two around about 75. It's now been
00:28:31 --> 00:28:31 refined.
00:28:31 --> 00:28:33 >> It's kind of what they're doing with
00:28:33 --> 00:28:34 this, isn't it?
00:28:34 --> 00:28:36 >> A little bit, although they're they're
00:28:36 --> 00:28:40 really giving tight very tight um
00:28:40 --> 00:28:42 estimates based on everything that we
00:28:42 --> 00:28:43 can observe, right?
00:28:43 --> 00:28:46 >> Uh whereas the previous this with it the
00:28:46 --> 00:28:48 difference between 50 and 100 and that
00:28:48 --> 00:28:50 was a kind of hollow tension. We didn't
00:28:50 --> 00:28:51 call it that, but that's sort of what it
00:28:51 --> 00:28:55 was. that uh was based on uh just
00:28:55 --> 00:28:58 individ individual measurements from you
00:28:58 --> 00:29:00 know their own particular school of
00:29:00 --> 00:29:02 thought. One was galaxies, one was
00:29:02 --> 00:29:03 supernovi or something. I can't remember
00:29:03 --> 00:29:05 how it worked. I can't remember the
00:29:05 --> 00:29:06 details. Probably could if I thought
00:29:06 --> 00:29:09 about it. Uh but this brings them all
00:29:09 --> 00:29:11 together to get this super accurate
00:29:11 --> 00:29:14 so-called value of 73.5.
00:29:14 --> 00:29:17 So the tension is that there is another
00:29:17 --> 00:29:21 way of uh determining the Hubble
00:29:21 --> 00:29:23 constant and it involves uh observing
00:29:23 --> 00:29:25 the cosmic microwave background
00:29:25 --> 00:29:27 radiation. That's the radiation that we
00:29:27 --> 00:29:29 see from the big bang. We're looking
00:29:29 --> 00:29:32 back 13.8 billion years to see that
00:29:32 --> 00:29:34 what's sometimes called the afterglow of
00:29:34 --> 00:29:36 the Big Bang. It's really still the
00:29:36 --> 00:29:37 light of the Big Bang that you can see
00:29:37 --> 00:29:39 because you're looking so far back in
00:29:39 --> 00:29:39 time.
00:29:39 --> 00:29:40 >> Yeah.
00:29:40 --> 00:29:42 >> And that gives us a different number.
00:29:42 --> 00:29:45 You can you can look at the um it's
00:29:45 --> 00:29:47 what's called the power spectrum. The
00:29:47 --> 00:29:48 the the cosmic microwave background
00:29:48 --> 00:29:51 radiation has these tiny tiny
00:29:51 --> 00:29:53 fluctuations and by tiny I mean the
00:29:53 --> 00:29:55 amount fluctuations in temperature. You
00:29:55 --> 00:29:56 can measure the temperature of the
00:29:56 --> 00:29:59 radiation and they they form in little
00:29:59 --> 00:30:01 blobs and we think that's where the
00:30:02 --> 00:30:03 galaxies came from. The the cooler parts
00:30:03 --> 00:30:06 were where galaxies formed. The warmer
00:30:06 --> 00:30:09 parts were not. Uh, and so this the
00:30:09 --> 00:30:11 microwave background radiation when you
00:30:11 --> 00:30:13 when you look at it, it looks like it
00:30:13 --> 00:30:16 looks like a p a wallpaper pattern. Uh,
00:30:16 --> 00:30:17 which is why I sometimes call it the
00:30:17 --> 00:30:19 cosmic wallpaper. Partly because it's
00:30:19 --> 00:30:21 behind everything else just like the
00:30:21 --> 00:30:22 wallpaper in a room is behind
00:30:22 --> 00:30:23 everything.
00:30:23 --> 00:30:23 >> Yeah.
00:30:23 --> 00:30:25 >> Uh, but it's also got these patterns. So
00:30:25 --> 00:30:27 you can use those patterns to make
00:30:27 --> 00:30:30 another estimate of the uh Hubble
00:30:30 --> 00:30:33 constant. And the answer that you get is
00:30:33 --> 00:30:37 67 kilometers/s per mega parse which is
00:30:37 --> 00:30:41 well outside the error band of the sort
00:30:41 --> 00:30:43 of traditional method.
00:30:43 --> 00:30:47 >> And so I think what the direction this
00:30:47 --> 00:30:50 is going in is so as you and I have
00:30:50 --> 00:30:53 spoken about before people have done a
00:30:53 --> 00:30:55 lot of work to try and look for where
00:30:56 --> 00:30:57 we've gone wrong here because these two
00:30:57 --> 00:30:59 numbers should give you the same answer
00:30:59 --> 00:31:02 but they don't. that they don't.
00:31:02 --> 00:31:04 >> And so now people are turning it upside
00:31:04 --> 00:31:06 down and saying maybe the fact that they
00:31:06 --> 00:31:08 don't give the same answer is telling us
00:31:08 --> 00:31:09 something about the physics of the
00:31:09 --> 00:31:12 universe that we don't know
00:31:12 --> 00:31:14 >> or we're just not accounting for
00:31:14 --> 00:31:16 everything we need to put into the
00:31:16 --> 00:31:16 formula.
00:31:16 --> 00:31:19 >> Yeah. Yeah. There's that too. And but I
00:31:19 --> 00:31:21 think that's so as time goes on people
00:31:21 --> 00:31:23 are ticking off all those things
00:31:23 --> 00:31:25 >> uh simply because there's a lot more
00:31:25 --> 00:31:28 work being done on this on this topic.
00:31:28 --> 00:31:30 So the Hubble tension could turn out to
00:31:30 --> 00:31:34 be uh the gateway into new physics that
00:31:34 --> 00:31:37 might tell us about dark matter and dark
00:31:37 --> 00:31:39 energy and all the other dark stuff that
00:31:39 --> 00:31:41 we we think about. Yeah. So it's it's
00:31:42 --> 00:31:45 potentially uh something that I think uh
00:31:45 --> 00:31:47 scientists everywhere will keep an eye
00:31:47 --> 00:31:50 on. Uh but it is really um really in
00:31:50 --> 00:31:52 many ways getting quite exciting that
00:31:52 --> 00:31:54 this Hubble tension is not going away.
00:31:54 --> 00:31:56 >> No, definitely not. It's come up a few
00:31:56 --> 00:31:58 times in the last 10 years that we've
00:31:58 --> 00:32:00 been doing this. So, they keep looking
00:32:00 --> 00:32:01 at it and that's and very good reasons
00:32:02 --> 00:32:04 to do so. Uh, for the record, a mega
00:32:04 --> 00:32:07 parseek is approximately 3.26 million
00:32:07 --> 00:32:08 lighty years. I think that's what you
00:32:08 --> 00:32:09 said.
00:32:09 --> 00:32:10 >> That is what I said. Yeah. I could never
00:32:10 --> 00:32:13 remember. I think it's 3.26. I told
00:32:13 --> 00:32:14 >> that's what I found. Yes.
00:32:14 --> 00:32:16 >> Yeah. Very good. All right. Uh,
00:32:16 --> 00:32:18 hopefully they've finally cracked the
00:32:18 --> 00:32:21 Hubble tension debate. Uh, I guess we'll
00:32:21 --> 00:32:22 find out if they keep coming up with
00:32:22 --> 00:32:25 different numbers in in the future, but
00:32:25 --> 00:32:26 uh, you can look it up at daily
00:32:26 --> 00:32:29 galaxy.com or you can read the published
00:32:29 --> 00:32:32 paper at astronomy and astrophysics.
00:32:32 --> 00:32:34 Fred, that brings us to the end of the
00:32:34 --> 00:32:36 program. Thank you so much.
00:32:36 --> 00:32:38 >> A great pleasure, Andrew. Uh, we've
00:32:38 --> 00:32:41 covered some great topics today and, uh,
00:32:41 --> 00:32:42 it's always a delight.
00:32:42 --> 00:32:44 >> Yeah, it's very, very, you know, a few
00:32:44 --> 00:32:46 different types of stories this time
00:32:46 --> 00:32:48 around, which we like. We'll catch you
00:32:48 --> 00:32:50 on the next one, Fred.
00:32:50 --> 00:32:52 >> Uh, I guess we will. Yes, sounds good.
00:32:52 --> 00:32:54 >> Professor Fred Watson, astronomer at
00:32:54 --> 00:32:56 large. And thanks to Hugh in the studio.
00:32:56 --> 00:32:58 He couldn't be with us today because he
00:32:58 --> 00:33:03 caused a bit of hubby tension at home
00:33:03 --> 00:33:04 and he's been sent to the naughty
00:33:04 --> 00:33:06 corner. Uh, don't forget to visit us
00:33:06 --> 00:33:09 online or um visit us on social media
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00:33:15 --> 00:33:19 or spacenuts.io. io and uh leave reviews
00:33:19 --> 00:33:21 from your favorite podcasting platform
00:33:21 --> 00:33:23 in the meantime. From me, Andrew Dunley,
00:33:24 --> 00:33:24 thanks for your company. We'll see you
00:33:24 --> 00:33:27 on the very next episode of Space Nuts.
00:33:27 --> 00:33:27 Bye-bye.
00:33:28 --> 00:33:29 >> Space Nuts.
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