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Dark Matter Mysteries, Telescope Innovations & the Quest for Gravitons | SN602 Q&A | Space Nuts:... · Space News Today

• 0:00
  Hi there. Thanks again for joining us.
• 0:02
  This is Space Nuts, a Q&A edition. This
• 0:04
  is where we answer audience questions.
• 0:07
  Well, we read them out and then we
• 0:09
  pretend we know what we're talking about
• 0:11
  and most people fall for it. They might
• 0:14
  not fall for it today, though, because
• 0:15
  we've got some uh really interesting
• 0:17
  questions about uh a matter of matter
• 0:20
  that we cannot see. Uh does it matter?
• 0:23
  We will find out. Um questions come up
• 0:26
  about gravitons. We're also going to
• 0:29
  answer a question about space
• 0:30
  telescopes. Now, that's right up uh
• 0:33
  Fred's alley. He knows everything there
• 0:35
  is to know about space te. He's written
• 0:37
  books about these things. So, this is
• 0:39
  going to be a good question. And uh a
• 0:42
  question has come up about whether or
• 0:43
  not Olympus Mons might make a good
• 0:46
  staging staging point for a space
• 0:48
  elevator. We will answer all of that on
• 0:51
  this episode of Space Nuts.
• 0:53
  >> 15 seconds. Guidance is internal. 10 9
• 0:58
  ignition sequence start.
• 1:00
  >> Space nuts.
• 1:01
  >> 5 4 3 2
• 1:03
  >> 1 2 3 4 5 5 4 3 2 1
• 1:06
  >> Space nuts.
• 1:07
  >> Astronauts report. It feels good.
• 1:10
  >> And it feels good to have his one and
• 1:13
  only self, Professor Fred Watson, an
• 1:15
  astronomer at large, back in the chair.
• 1:16
  Hello, Fred. Hello. Hello. Here. All
• 1:19
  ready to go. Fresh and um uh well slept.
• 1:24
  Yeah. So, sort of.
• 1:26
  >> Yeah. I had a weird night last night. I
• 1:28
  I I actually went to sleep fast. Didn't
• 1:31
  I I only woke up kind of and once once,
• 1:33
  which is, you know, a new world record.
• 1:36
  And then um I woke up again 5 5:18 a.m.
• 1:41
  And that was it. My body went, "No, no,
• 1:43
  we're done. You can get up. Go and watch
• 1:45
  something on television because I'm not,
• 1:47
  you know, I don't want to go any to
• 1:49
  sleep ever again." So, here we go. Who
• 1:52
  knows what'll happen tonight. Um, sleep
• 1:54
  is a weird thing. We need it and yet our
• 1:57
  bodies sometimes refuse to comply.
• 2:01
  >> Yeah.
• 2:01
  >> Yeah,
• 2:02
  >> it is. It's bizarre. It's a strange
• 2:03
  thing.
• 2:05
  >> Um, shall we answer some questions?
• 2:08
  >> I thought that was it.
• 2:09
  >> Well, I was just going to say, Fred, why
• 2:11
  can't I sleep?
• 2:13
  >> Let's answer some questions. Yes.
• 2:15
  >> Okay. Our first one comes from Ben. He
• 2:17
  says, uh, Ben here. It's good because I
• 2:20
  thought he was Ben, too. uh the Aussie
• 2:22
  in Chicago with a few new questions. In
• 2:24
  your last question podcast, you
• 2:26
  mentioned about how 80% of matter is
• 2:28
  missing or not visible to us. And it
• 2:31
  made me think, how do we know or measure
• 2:34
  that amount in the first place? I know a
• 2:37
  lot of science is about measuring what
• 2:39
  we didn't find in results, but I'm
• 2:42
  curious about how they came to that 80%
• 2:44
  dark matter number. And secondly, uh,
• 2:48
  for a smaller question, if you could
• 2:50
  pick the next large telescope to be
• 2:52
  launched, what would it be and why? I'd
• 2:55
  personally love to see a new larger
• 2:57
  Hubble type telescope with all the
• 2:59
  advances we've applied to it uh, that
• 3:02
  we've learned from the James Webb Space
• 3:03
  Telescope. Thanks again for the great
• 3:05
  podcast. Thank you, Ben. Great to hear
• 3:07
  from you. Hope all is well in uh, in
• 3:10
  Chicago, home of the Bears. Chicago
• 3:12
  Bears.
• 3:14
  Um right so it's a matter of matter and
• 3:19
  um he's saying we know there's 80% of
• 3:22
  the universe made up of dark matter or
• 3:24
  thereabouts. Uh how do we know that?
• 3:29
  Um we actually the the way that we get
• 3:33
  the you know the accurate figures is
• 3:36
  quite interesting because it involves
• 3:38
  work um of the kind that wasn't possible
• 3:42
  before astronomers started using fiber
• 3:44
  optics in their telescopes and uh that's
• 3:48
  what I did. I was one of the pioneers of
• 3:51
  fiber optics in astronomy. uh and the
• 3:54
  systems that we built back in the 80s,
• 3:56
  the 1980s have now evolved into
• 3:59
  marvelous machines which are fully
• 4:02
  automated. Um the uh organization that I
• 4:06
  worked for has just delivered one to
• 4:08
  Chile which will position 2,400 fibers
• 4:12
  in 57 seconds. Uh and each one of those
• 4:15
  fibers can be aligned with a target star
• 4:18
  or galaxy. uh and that's the way you
• 4:21
  collect lots of information about very
• 4:23
  large numbers of galaxies and about uh
• 4:26
  their velocities what we call their red
• 4:28
  shifts. So we'll get to that in a minute
• 4:30
  because that's that's how we are so
• 4:32
  certain about these numbers because of
• 4:34
  the ability to do that to measure these
• 4:37
  very large numbers of galaxies what we
• 4:38
  call large scale surveys. But the story
• 4:41
  starts uh back in 1933 with Fritz Vicki
• 4:46
  uh the man who famously called some of
• 4:49
  his colleagues uh not just bastards they
• 4:52
  were spherical bastards. Uh the reason
• 4:54
  for that was that they were bastards
• 4:56
  whichever way you looked at them. That's
• 4:58
  why call them spherical bastards.
• 5:01
  >> Astron astronomers love him. Yeah,
• 5:03
  >> I'm sure they do. Yeah. Um, I usually
• 5:07
  tone that down a bit and make it rat
• 5:09
  bags, but for this show I can re
• 5:12
  >> I could quote him verbatim.
• 5:14
  >> It is a quote. Therefore, it's it's a
• 5:16
  quote. Yeah, it's part of it's a part of
• 5:18
  history.
• 5:19
  >> It is indeed part of history. Um, but
• 5:22
  what he was doing was measuring a
• 5:24
  cluster of galaxies actually in the
• 5:26
  northern hemisphere constellation of
• 5:27
  Koma Bernese. Uh, the Koma cluster, a
• 5:30
  very rich cluster of galaxies. And he
• 5:31
  figured out that the he was measuring
• 5:34
  the motions of all the galaxies. And
• 5:36
  when he looked at it, they were all
• 5:38
  going too fast for the gravity of what
• 5:41
  he could see to hold on to them.
• 5:43
  >> So if all that was uh there was what all
• 5:46
  he could see, then this cluster should
• 5:48
  have evaporated gazillions of years ago
• 5:51
  and it hasn't. And he was the person who
• 5:54
  coined the term dark matter. Uh he said
• 5:56
  there's something there that we can't
• 5:58
  see. the ast world of astronomy
• 6:00
  basically ignored it because it was just
• 6:02
  too hard to get your head around.
• 6:04
  There's obviously something wrong. We
• 6:06
  don't know what it is. We'll go and do
• 6:07
  something else. And it wasn't until well
• 6:10
  actually there was an Australian who um
• 6:12
  in 1970 Ken Freeman down at the A&U
• 6:15
  still a good friend uh he um figured out
• 6:19
  that galaxies were rotating too fast for
• 6:22
  the what was in them to hold them
• 6:24
  together. Uh and um that again was
• 6:27
  largely ignored that 1970 result until
• 6:30
  Vera Rubin um basically did the same
• 6:34
  thing but worked out that in order for
• 6:36
  galaxies to stay together and not fly
• 6:39
  apart as they rotate, they must all be
• 6:42
  enveloped in a sort of sphere or halo as
• 6:45
  we call it of something we call dark
• 6:47
  matter. And that in 1978 was the start
• 6:49
  of the modern era of dark matter. And so
• 6:52
  you can actually use those uh those
• 6:55
  measurements to make a crude estimate of
• 6:57
  what's missing. You know that you can
• 6:59
  say use something called the viral
• 7:01
  theorem which I haven't thought about
• 7:03
  for a long time. But that's what lets
• 7:05
  you weigh things by their motion. So you
• 7:07
  can weigh the dark matter uh by the
• 7:10
  motion of galaxies in a cluster for
• 7:12
  example. You can then weigh what you can
• 7:16
  see because you know roughly how much
• 7:18
  stars weigh and the stars are what you
• 7:20
  can see and the gas too. and then you
• 7:22
  can divide one by the other and you do
• 7:24
  get this sort of 80-ish percent. Um, but
• 7:27
  the the way that it's done today, as
• 7:30
  I've said, it involves these very large
• 7:32
  scale surveys of galaxies and their
• 7:35
  positions and velocities in, you know,
• 7:38
  as much of the universe as you can see.
• 7:40
  Very, very large scale surveys involving
• 7:42
  millions of galaxies. And when you do
• 7:44
  that, you can make statistical
• 7:46
  deductions that tell you that uh the
• 7:48
  universe is made of something like 70%
• 7:50
  dark energy, uh about 20% dark matter,
• 7:54
  about 5% normal matter, uh most of which
• 7:57
  is hydrogen. So that that comes from the
• 7:59
  large scale surveys. And it's because
• 8:02
  the positions of galaxies are actually
• 8:05
  determined by the gravitational forces
• 8:07
  that they feel. And you know that's the
• 8:10
  key to understanding dark matter and
• 8:12
  dark energy to see how these forces
• 8:14
  stack up.
• 8:15
  >> It's so hard to comprehend because when
• 8:18
  you say that 5% of the universe is made
• 8:21
  up of stars, planets and gas, and you
• 8:24
  look out into space and see so many
• 8:26
  stars, so many other things, and yet
• 8:30
  you're only seeing 5% of what out what
• 8:32
  is out there. It's it's it's
• 8:34
  mind-blowing.
• 8:36
  >> That's right. I mean some of that that
• 8:39
  figure of 5% is the when you look at it
• 8:41
  as a fraction of the mass and energy
• 8:43
  budget and energy and matter you know
• 8:45
  they're interchangeable E= MC² uh and so
• 8:49
  uh it's when you do that some you
• 8:50
  realize that yes um 70% of the mass
• 8:55
  energy budget of the universe is dark
• 8:57
  energy uh 20% is dark matter 5%
• 9:00
  thereabouts uh is is normal matter but
• 9:04
  most of that normal matter is invisible
• 9:06
  to because most of it is just called
• 9:07
  hydrogen.
• 9:08
  >> Uh the the you know the materials that
• 9:10
  make up the the planets in particular
• 9:12
  the the um you know the normal elements
• 9:16
  that we see around us on earth there's a
• 9:19
  vanishingly small fraction of that uh
• 9:21
  that represents you know the their
• 9:23
  fraction within the universe.
• 9:25
  >> Yeah. All right. So that covers his 80%
• 9:28
  question. But uh he asks a question
• 9:30
  about what will be the next uh large
• 9:34
  telescope to be launched. What would you
• 9:36
  like it to be?
• 9:38
  >> Um, yeah, that's an interesting
• 9:39
  question. I mean, the thing that I'm
• 9:41
  looking forward to, and we'll see it
• 9:43
  online within the next probably two
• 9:45
  years, is the ELT, the extremely large
• 9:48
  telescope down in Chile. That's going to
• 9:50
  be a visible light telescope with uh a
• 9:53
  mirror 39 m in diameter.
• 9:58
  uh and it will be able to observe
• 10:00
  because it's got this very sophisticated
• 10:03
  adaptive optic system that effectively
• 10:06
  puts it above the atmosphere. Um it's uh
• 10:09
  it is uh it will have 20 times the
• 10:14
  resolution of the Hubble telescope. So
• 10:16
  if you thought the Hubble images that
• 10:18
  you see have fine detail in them, wait
• 10:20
  till you see what's going to come from
• 10:21
  the ELT because it'll be 20 times
• 10:23
  better. And the reason why that's my
• 10:27
  favorite big telescope is that its cost
• 10:30
  has been almost since the beginning
• 10:32
  estimated at 1.3 billion euros and it
• 10:35
  still is. Uh it's on on budget and
• 10:38
  pretty well on time. Uh and remember the
• 10:40
  James Webb telescope cost10 billion.
• 10:43
  >> Yeah.
• 10:44
  >> To build launch and and you know and
• 10:47
  keep it going. uh the
• 10:50
  as soon as you put things into space,
• 10:52
  the price tag goes up enormously, which
• 10:55
  is why I'm a big fan of groundbased
• 10:57
  astronomy, especially when we now have
• 10:59
  sites like Sarah Amazon is in northern
• 11:01
  Chile, which is where the ELT will be uh
• 11:04
  whose whose uh you know whose clarity
• 11:08
  and atmospheric stability you can hone
• 11:12
  with that adaptive optics system that
• 11:14
  the telescope's going to be fitted with.
• 11:17
  M.
• 11:17
  >> So, um, that's that's what I'm looking
• 11:19
  out for next. I don't think you need to
• 11:21
  launch anything else into space to get
• 11:23
  anywhere near what the ELT will do.
• 11:25
  >> Very exciting.
• 11:26
  >> Yeah. I heard they're going to have a
• 11:28
  visitors center at the ELT, but the only
• 11:30
  thing on the menu will be BLT, so
• 11:35
  I had to do that joke. It just, you
• 11:38
  know, my brain doesn't let me stop
• 11:40
  sometimes.
• 11:41
  >> No, it
• 11:44
  uh Thank you, Ben, for the question.
• 11:46
  Great to hear from you.
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• 13:09
  >> Roger, you're here also.
• 13:11
  >> Spacenuts. Uh, I'm going to do a bit of
• 13:13
  a switcheroo here because we we're
• 13:15
  already talking about telescopes and
• 13:16
  we've got a question about telescopes.
• 13:18
  So, we might just jump straight to that
• 13:20
  one. Uh, hi Fred and Andrew. Just
• 13:22
  wondering if Fred can shed some light,
• 13:26
  puny intended. Uh, on telescopes and the
• 13:29
  different types of light they can
• 13:30
  detect. I was recently thinking about
• 13:32
  how the James Webb Space Telescope uses
• 13:35
  mirrors to observe infrared light but
• 13:37
  not visible light while Hubble also uses
• 13:39
  mirrors for visible light yet can't
• 13:42
  really see infrared. Uh that got me
• 13:44
  wondering how mirrors, detectors and
• 13:47
  telescope design all come together or
• 13:49
  don't uh for different uh wavelengths.
• 13:52
  Could you please walk us through the
• 13:54
  various types of telescopes, optical,
• 13:56
  infrared, radio, all the way to gamma,
• 13:58
  and explain what kinds of light they
• 14:00
  detect, how they do it, and why each
• 14:02
  telescope can only be used in certain
• 14:04
  ways. Absolutely love the show. May your
• 14:07
  rain uh may you reign supreme for many
• 14:09
  years to come. Cheers, Ash. Thank you,
• 14:12
  Ash. And um yeah, he just wants to know
• 14:16
  everything you've ever written down
• 14:17
  about telescopes. Fred,
• 14:19
  >> yeah, there's a book on it. I I
• 14:20
  recommend Ash Hunted Out.
• 14:23
  >> It's called Star Stargazer, the life and
• 14:25
  times of the telescope. It's the first
• 14:27
  big thick book that I wrote. Uh and
• 14:30
  still one of my favorites because um
• 14:32
  even though it's slightly out of date,
• 14:34
  it opens by talking about what used to
• 14:36
  be called Owl, uh the overwhelmingly
• 14:39
  large telescope, which was actually the
• 14:41
  precursor of the ELT we were just
• 14:43
  talking about there, right? But when
• 14:45
  they were proposing owl um which had an
• 14:49
  overwhelmingly large mirror of 100 m in
• 14:51
  diameter and then they realized it also
• 14:54
  had an overwhelmingly large price tag
• 14:56
  which is why it came down to 39 m and
• 14:58
  that's fine because that's still an
• 15:00
  extremely big telescope. Anyway, um
• 15:02
  that's that's the plug over. That's the
• 15:04
  advert over. Uh so basically telescopes
• 15:09
  have sort of got the same ingredients no
• 15:12
  matter what they're observing. Uh and
• 15:15
  that is something to gather the
• 15:17
  radiation and whether that's very short
• 15:19
  wavelength radiation like gamma rays or
• 15:22
  long wavelength radiation like radio
• 15:25
  waves. Uh you've got something to gather
• 15:27
  the radiation uh and either focus it in
• 15:30
  some way or at least concentrate it and
• 15:32
  then something to detect it. And it's
• 15:35
  usually the detectors that are perhaps
• 15:39
  the most waveband critical because you
• 15:42
  need different detectors for example to
• 15:45
  detect visible light uh from the ones
• 15:48
  that you would use to detect infrared
• 15:50
  light. Um it's and and again it depends
• 15:53
  on the infrared wavelength. Uh so I I
• 15:57
  guess starting right at the the short
• 16:00
  wavelength end with gamma ray and x-ray
• 16:03
  detectors um they are almost the same
• 16:07
  sort of technology as as are used in
• 16:09
  medical imaging. Uh but to focus them
• 16:12
  you've got to have very special
• 16:14
  technologies. um my recollection of
• 16:16
  gammaray telescopes and things might
• 16:19
  have changed a little bit here but the
• 16:22
  they made mirrors which were called
• 16:24
  grazing incidence mirrors which looked
• 16:26
  more like a piece of origyami than than
• 16:29
  a a reflector that you'd imagine but
• 16:32
  they did focus the light to to provide
• 16:34
  that thing and then you go to
• 16:36
  ultraviolet the Hubble is sensitive to
• 16:39
  ultraviolet light um and that for that
• 16:41
  it needed a very precise mirror and we
• 16:43
  all know that the mirror was made very
• 16:45
  precisely but to the wrong prescription
• 16:48
  uh uh for reasons that we haven't time
• 16:50
  to go into. Uh so once again you know
• 16:53
  the detector is sensitive to ultraviolet
• 16:55
  radiation. In fact they've got wideband
• 16:57
  quite wideband detectors. Um Hubble can
• 17:00
  detect longwavelength ultraviolet
• 17:03
  whole of the visible and also the short
• 17:05
  wavelength infrared what we call the
• 17:08
  near infrared. Uh and its mirror and
• 17:10
  detectors are capable of doing that.
• 17:12
  When you go up to the James Web, you're
• 17:14
  right. That's tuned for infrared light.
• 17:17
  And that means your tolerances on the
• 17:20
  accuracy of the mirror are slightly less
• 17:22
  because infrared light's got a longer
• 17:24
  wavelength. And you know how how
• 17:28
  accurate your mirror mirror needs to be
• 17:30
  made is dependent on the wavelength. The
• 17:32
  longer the wavelength, the more relaxed
• 17:34
  you can be about the shape of the
• 17:36
  mirror. Uh so web telescope slightly
• 17:39
  more relaxed although still to very high
• 17:42
  tolerances but the detectors are the
• 17:44
  thing that really render it uh not
• 17:46
  suitable for visible light uh it's got
• 17:49
  definitely got infrared uh sensitive
• 17:51
  detectors.
• 17:53
  It's also got a gold coating uh and
• 17:56
  that's so that rather than a an
• 17:58
  aluminium or silver coating like a
• 18:00
  visible light telescope would have, it's
• 18:02
  got a gold coating because gold reflects
• 18:04
  infrared light better. And then you get
• 18:06
  up to radio waves and you're talking
• 18:08
  about um often dishes and you know a
• 18:11
  dish is just a big mirror but uh one
• 18:15
  that's as I said before it doesn't have
• 18:17
  to be as accurate as the mirror on a
• 18:19
  visible light telescope because the
• 18:20
  wavelength is longer and that's why we
• 18:22
  see these much bigger bigger telescopes
• 18:25
  for radio waves. Uh you get the same
• 18:29
  um sensitivity to detail uh with a
• 18:31
  bigger dish than you do with visible
• 18:33
  light. with a smaller dish. That's
• 18:35
  because that sensitive to details
• 18:37
  proportional to the wavelength. Um, but
• 18:39
  the detectors are quite different in
• 18:42
  radio telescopes. They use often very
• 18:45
  sophisticated technologies where they're
• 18:46
  actually measuring the waveform itself,
• 18:49
  which you don't do with visible light,
• 18:51
  what are called hetradine receivers and
• 18:53
  things of that sort. So, um, that's
• 18:55
  walking through the various types of
• 18:57
  telescopes as you've suggested. Ash, is
• 19:00
  there another bit to the question uh,
• 19:02
  how they do it? Well, I've explained
• 19:04
  that why each telescope can only be used
• 19:06
  in certain ways. Yeah.
• 19:07
  >> Yeah. I guess the question he asks
• 19:10
  prompts a question in my mind or a
• 19:11
  suggestion that you really could not
• 19:13
  build a single telescope that could do
• 19:16
  absolutely everything you'd want to do
• 19:18
  on all spectrums.
• 19:21
  >> Um that's correct. There is a there is a
• 19:24
  device
• 19:25
  which uh in fact is only used really in
• 19:28
  the microwave region of the spectrum. uh
• 19:31
  but it's called a bometer and a bometer
• 19:34
  is something that is basically detects
• 19:36
  stuff but it's insensitive to
• 19:38
  wavelength. So in a sense a bometer a
• 19:41
  perfect bometer will be able to detect
• 19:43
  all wavelengths. Now the reality is you
• 19:45
  can't do that but that's the notion
• 19:47
  behind a bometer and what it means is
• 19:50
  that for microwave astronomy um the
• 19:54
  bometer gives you a very wide range of
• 19:56
  wavelengths to cover. So when you are
• 20:00
  planning to build a telescope,
• 20:02
  do you have an objective in mind before
• 20:04
  you build it or do you build it and then
• 20:07
  think well what can we do this?
• 20:09
  >> No, it's definitely the other way
• 20:11
  around. You you start off with a science
• 20:13
  case. What are the questions that we
• 20:15
  really think are the most urgent
• 20:17
  questions to answer? And you've got
• 20:20
  things like um you know the nature of
• 20:22
  dark energy, the nature of dark matter.
• 20:25
  Uh are there any living organisms
• 20:27
  anywhere else in the univer all the all
• 20:28
  the questions that you and I talk about
• 20:29
  on the show are the ones that scientists
• 20:32
  are still intrigued by and there are
• 20:34
  many others as well. The details of the
• 20:35
  way galaxies interact with environments.
• 20:38
  What about all these um young galaxies
• 20:41
  that seem to be more mature than we
• 20:44
  think they should be at, you know, when
• 20:46
  the universe is only a couple hundred
• 20:47
  million years old? Questions like that.
• 20:49
  They're all the ones that would go into
• 20:51
  the science case for a project. But
• 20:54
  there is always the background that
• 20:56
  you're going to find things out that you
• 20:58
  simply did not expect to find out. So
• 21:01
  that's usually added into the science
• 21:03
  case. The stuff that we just don't
• 21:05
  expect. Serendipitous discovery. There's
• 21:07
  been so many of those um made by the
• 21:10
  world's great telescopes.
• 21:12
  >> Yeah, thank you Ash. That's a great
• 21:14
  question and I could tell Fred was
• 21:16
  excited about it. I I'm just going to go
• 21:18
  I'm going to go back to Ben's question
• 21:19
  about, you know, what do you want the
• 21:21
  next um big thing in telescopes to be?
• 21:23
  I've thought of one. I I want to see the
• 21:25
  FWST.
• 21:28
  >> Uh Fred Watson Space Telescope. That's
• 21:32
  that's what I
• 21:32
  >> want to sound. Yeah, I do too.
• 21:34
  >> I want the sound of that. Thank you. Oh,
• 21:36
  well, you're a pioneer in fiber optics.
• 21:38
  I mean, it makes sense to me that you
• 21:39
  should have one named after you.
• 21:42
  >> Yeah.
• 21:42
  >> I always um I always think the reason
• 21:45
  for my hairstyle is because I worked in
• 21:47
  fiber optics cuz the individual
• 21:49
  follicules got jealous of all these thin
• 21:52
  strands of material that I was playing
• 21:53
  with and they all just fell out.
• 21:55
  >> Yeah, they gave up. Yeah. They said,
• 21:56
  "No, we can't beat that. See you later,
• 21:58
  France.
• 22:00
  We're going somewhere else." Uh, thanks
• 22:02
  Ash for the for the question. And this
• 22:04
  is Space Nuts with Andrew Dunley and
• 22:06
  Professor Fred Watson, a Q&A edition.
• 22:10
  Let's tell you about our sponsor,
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• 23:38
  >> Swift
• 23:40
  base here. The angle has landed.
• 23:42
  >> Space nets.
• 23:43
  >> Our next question comes from somebody
• 23:47
  else. Uh, hi Fred and Andrew. Gravity is
• 23:49
  described by Einstein's theories as the
• 23:52
  bending of spaceime in the presence of
• 23:54
  massive objects. Great. Why then does
• 23:58
  physics discuss the hypothetical
• 24:00
  graviton as a force carrier for gravity?
• 24:03
  Uh what would a graviton look like were
• 24:06
  we to discover it uh or discover its
• 24:08
  existence? And why is it needed at all
• 24:11
  in the context of Einstein's theory?
• 24:14
  Thanks. Keep up the good work. Love the
• 24:15
  show. Russ from Stalbridge
• 24:19
  in the UK. Stalbridge
• 24:21
  >> it is. That's right. It's in the
• 24:22
  Midlands. Stbridge, I think, if I
• 24:25
  remember rightly.
• 24:26
  I mean,
• 24:28
  >> um, yeah, it's a good question. Uh, and
• 24:32
  that's kind of hard to know how to how
• 24:35
  to start it because there's so much to
• 24:38
  say. So, um, yes, general relativity,
• 24:42
  exactly as Ross says, uh, is that
• 24:45
  spacetime bends, uh, or the theory says
• 24:48
  spacetime bends, uh, when you've got
• 24:50
  matter there. Uh, and all the evidence
• 24:54
  is that general relativity is absolutely
• 24:56
  on the money. It's um, you know, it
• 24:59
  meets its predictions with with such a
• 25:03
  high level of accuracy that it's almost
• 25:05
  mind-blowing. If I remember rightly, I
• 25:07
  think it's one part in 10 to the 18 or
• 25:09
  something like that that it's been
• 25:11
  proven to work uh for. So uh that's
• 25:15
  great but um the physicists who look at
• 25:20
  the other end of the of the size scale
• 25:23
  the ones who are interested in quantum
• 25:25
  mechanics and uh you know particle
• 25:28
  physics uh sub subatomic particles they
• 25:33
  say that all forces
• 25:36
  uh and and here we're talking about
• 25:38
  gravity in the Newtonian sense that it's
• 25:41
  a force uh have have a particle that
• 25:44
  carries them. And so, you know, we've
• 25:47
  got the photon for electromagnetic
• 25:49
  force. We've got the um the various uh
• 25:53
  force carriers for the strong and weak
• 25:56
  nuclear forces. Um and we've also got
• 25:59
  now the Higs field, the the the Higs
• 26:03
  Bzon. So what they're saying is that the
• 26:06
  because gravity works that way there
• 26:08
  should be a bzon that carries gravity
• 26:12
  and that's the idea of a hypothetical
• 26:14
  graviton. Um my suspicion as to how that
• 26:19
  links with relativity comes from the the
• 26:23
  the
• 26:25
  description of uh of the Higs Bzon that
• 26:28
  I think we might have talked about a few
• 26:30
  weeks ago. So the Higs Bzon is I think
• 26:35
  somebody asked about you know how how do
• 26:37
  you reconcile the Higs Bzon with
• 26:39
  something that gives all the other
• 26:40
  forces their their mass
• 26:43
  >> because that's what the Bzon does. And
• 26:46
  the bottom line is that what you're
• 26:47
  really talking about is the Higs field,
• 26:49
  which is something like they usually
• 26:52
  talk about syrup or molasses. Uh, and as
• 26:55
  the particles move through it, they get
• 26:57
  they get resistance because they're uh,
• 27:00
  you know, because they're in this sticky
• 27:01
  stuff. Uh, and that gives them the
• 27:05
  effect of mass. It's not an analogy that
• 27:08
  thrills me, I have to say, but it kind
• 27:11
  of gets the idea. And the only time the
• 27:14
  Higs Bzon itself appears is when you've
• 27:17
  got something a collision between
• 27:20
  particles. So the Higs field is is the
• 27:23
  main thing. But if you collide particles
• 27:25
  together, you get this thing that
• 27:28
  emerges from the Higs field which is
• 27:30
  called the Higs Bzon. And that can be
• 27:32
  measured which it was in 2012. And my
• 27:35
  guess is that gravity, the graviton
• 27:37
  would be something like it. It would be
• 27:39
  a Bzon. it would emerge from the gravity
• 27:41
  field maybe would emerge when there were
• 27:44
  collisions in particle accelerators but
• 27:47
  we have no evidence for it yet. So um I
• 27:50
  think um you know Russ I think that's
• 27:52
  the bottom line that uh like the search
• 27:55
  for the Higs Bzon one day the Higs the
• 27:58
  search for the graviton will basically
• 28:01
  cough up the goods uh and uh and we'll
• 28:04
  we'll understand it perhaps in a similar
• 28:06
  way to the way we understand the Higs
• 28:08
  Bzon that you need um to actively create
• 28:11
  a Bzon from the Higs field. So maybe you
• 28:14
  need to create a graviton from the
• 28:16
  gravity field which we're used to
• 28:18
  talking about
• 28:18
  >> and some kind of particle to account for
• 28:21
  dark matter and so
• 28:22
  >> well that's right. Yes. Yeah. Well dark
• 28:24
  matter would probably be a firm on a
• 28:28
  thing that you know is a matter particle
• 28:29
  rather than a force particle.
• 28:31
  >> Okay. Gotcha. Fair enough. All right. Uh
• 28:34
  so where does a light particle fit in
• 28:37
  that? A photon.
• 28:38
  >> Uh that's the photon. Yeah. It's a
• 28:39
  gravitational it's the electromagnetic
• 28:42
  particle. That's pro probably the best
• 28:43
  understood of of the subatomic particles
• 28:46
  because we use it all the time.
• 28:48
  >> We're using it as we speak.
• 28:50
  >> We are. It's very It's very handy.
• 28:53
  >> It's very handy. Yeah. I found it quite
• 28:55
  useful recently.
• 28:57
  >> Good. Very
• 28:58
  >> You probably find the strong and weak
• 29:00
  nuclear forces quite useful as well
• 29:02
  because they stop you falling to bits.
• 29:04
  >> That's a good one. Keep that in mind.
• 29:07
  >> Yeah, I think that's even more useful
• 29:09
  than photon. Really? The problem with
• 29:11
  all of this, Fred, is none of it gives
• 29:13
  me anything to work with to improve my
• 29:15
  golf game. So,
• 29:18
  >> uh, yeah. Well, you've got to start with
• 29:21
  the notion that five irons don't float.
• 29:24
  And once you've got past that step, then
• 29:27
  >> you were getting some book plugs in
• 29:29
  today.
• 29:30
  >> That's one for you. Thank you very much.
• 29:33
  Uh, thank you, Russ. I I hope we covered
• 29:35
  that. I think we did. Not sure, but
• 29:37
  anyway. Um, it it's a work in progress.
• 29:40
  We'll call it that. Uh our final
• 29:42
  question today uh comes from Robert. He
• 29:45
  said, "Hi, my friends down under. I live
• 29:47
  in Areri, Iceland,
• 29:50
  and I'm very much looking forward uh to
• 29:52
  the eclipses this year in the western
• 29:54
  part of Iceland. However, um your recent
• 29:58
  fabulous show regarding Olympus bonds on
• 30:00
  Mars, would this make a perfect
• 30:02
  candidate for a space elevator?" Uh that
• 30:06
  comes from Robert. Hello, Robert. Thanks
• 30:08
  for uh sending your question in
• 30:10
  Arerrera. You've been there.
• 30:12
  >> I have. Yes. I sent you some photographs
• 30:14
  so you could see what it's like. Uh we
• 30:16
  should put them up on the website if
• 30:18
  >> we could post them on in the Space Nuts
• 30:20
  podcast group.
• 30:21
  >> That would be nice. All right. One of
• 30:23
  the main street main and me in the main
• 30:25
  street in Akaria. We were there at this
• 30:27
  time last year actually. Okay. Uh
• 30:30
  Robert. So um I'm sorry I didn't know
• 30:32
  you then or else we'd have looked you
• 30:34
  up. But we had a great time there. It
• 30:36
  was part of our our ice land tour which
• 30:39
  was not the best for weather. So, we
• 30:41
  didn't see any aori, but uh certainly
• 30:44
  experienced some really fabulous
• 30:47
  landscapes up in the northwest of
• 30:49
  Iceland. It was the first our first
• 30:50
  visit up to the northwest. We spent a
• 30:52
  lot of time in the south on previous
• 30:54
  trips, but uh yeah, Aari such a stunning
• 30:57
  place. Beautiful scenery.
• 30:59
  >> They they love their cathedrals, don't
• 31:01
  they? In Iceland, the churches, gee,
• 31:04
  they're amazing. The one the one we saw
• 31:06
  in Rekuik just blew my mind.
• 31:08
  >> That's right. That's that's the classic
• 31:10
  one. That is such an elegant building.
• 31:13
  It is.
• 31:13
  >> And indeed the church in Nakureri is
• 31:15
  lovely as well.
• 31:16
  >> It is. Yeah, you got a photo of that
• 31:18
  one. Yeah, I'll post that too.
• 31:21
  >> Uh what was the question again? Oh yeah.
• 31:25
  >> As a good platform for a space elevator.
• 31:28
  Um the yes um there's a kind of problem
• 31:34
  because to make a space elevator stable
• 31:39
  uh it has to start off from a point on
• 31:43
  the equator of whatever world you're
• 31:45
  trying to get up into space from. Right.
• 31:48
  And Olympus Mons, I am told, is at
• 31:52
  latitude 18° north. In fact, it's 18° 39
• 31:57
  minutes north, which is not the equator
• 31:59
  of Mars. So, you'd have problems with
• 32:02
  it. Uh, it would need to stretch and
• 32:04
  shrink uh and I think would probably
• 32:06
  shake itself to pieces. So, uh I think
• 32:09
  you've got to have the equator. So
• 32:11
  that's a bit sad because Olympus Mons as
• 32:14
  um as Robert is hinting at uh is um you
• 32:19
  know it's high enough that you kind of
• 32:22
  already you're already out.
• 32:24
  >> Well, you're already Yeah, you're
• 32:25
  already on the way up your space
• 32:27
  elevator. So, a nice idea. Very nice
• 32:29
  idea, but I don't think it would work.
• 32:31
  >> That's a pity. Well, I I suspect that uh
• 32:35
  the space elevator concept's probably
• 32:38
  not ever going to happen. And it just
• 32:40
  sounds like it's too expensive, too
• 32:41
  hard, and there are easier ways to do
• 32:43
  things.
• 32:44
  >> Yeah. Well, that's right. Reusable
• 32:46
  boosters is the way to do it. And uh as
• 32:48
  we talked about in the last show, that's
• 32:49
  now basically the normal way of getting
• 32:52
  into space.
• 32:54
  >> Very much so, Robert. Great to hear from
• 32:55
  you. Enjoy those eclipses later this
• 32:58
  year. Uh yeah, that that'll be very
• 33:00
  exciting in Iceland if you can get
• 33:02
  there. Uh be a lot of fun, too. Um so,
• 33:05
  Robert, hopefully we answered your
• 33:07
  question. It was an easy one as it turns
• 33:09
  out. U and that brings us to an end.
• 33:11
  Don't forget if you've got questions for
• 33:13
  us, please send them in. We we're
• 33:14
  actually quite desperately short of
• 33:16
  questions. So, uh send them to us via
• 33:19
  our website spacenutspodcast.com.
• 33:21
  spacenuts.io
• 33:22
  or just do a search for spaceodcast on
• 33:25
  your favorite search engine. Click on
• 33:27
  the AMA button that is ask me anything
• 33:30
  and send your text and audio questions
• 33:31
  in with your name and location. We would
• 33:34
  really love to hear from you. Fred,
• 33:36
  we're all done. Thank you so much. It
• 33:38
  was good fun today.
• 33:39
  >> Yeah, it's been great.
• 33:41
  >> Oh, it's never It's never fun any other
• 33:42
  time, but it was good fun today.
• 33:45
  >> I love connecting with our listeners.
• 33:47
  It's especially when they're in places
• 33:49
  like Arureri.
• 33:51
  >> Yeah. Yeah. What a what an amazing
• 33:53
  place. See you soon, Fred.
• 33:55
  >> Cheers for now.
• 33:56
  >> Professor Fred Watson, astronomer at
• 33:58
  large, part of the team here at Space
• 34:00
  Nuts. And uh thanks to Hugh in the
• 34:03
  studio, uh works really hard, but he
• 34:05
  couldn't be with us today. He got on a
• 34:06
  space elevator and he thought he'd be
• 34:08
  back in time, but some kid pushed all
• 34:10
  the buttons. So, he was he was very
• 34:14
  angry. Anyway, he sent me a text. Uh,
• 34:16
  and from me, Andrew Dunley, thanks for
• 34:18
  your company. We'll catch you on the
• 34:20
  next episode of Space Nuts. Bye-bye.
• 34:22
  >> Space Nuts.
• 34:23
  >> You'll be listening to the Space Nuts
• 34:25
  podcast
• 34:27
  >> available at Apple Podcasts, Spotify,
• 34:30
  iHeart Radio, or your favorite podcast
• 34:33
  player. You can also stream on demand at
• 34:35
  byes.com. This has been another quality
• 34:38
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