Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / Cosmic Queries Unleashed: Gravitons, Expanding Universes & the Weight of Space Travel

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Cosmic Queries Unleashed: Gravitons, Expanding Universes & the Weight of Space Travel · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Andrew Dunkley: Hello again. Thanks for joining us. This is a
• 0:02
  Q and A edition of Space Nuts. We talk
• 0:05
  astronomy, space science, and answer
• 0:07
  audience questions. Well, maybe we won't do
• 0:10
  one of those three things today. I don't
• 0:12
  know. We'll see how it goes. Uh, we've got a
• 0:14
  lot of questions to get through today. Um,
• 0:16
  Fred Watson reckons some of these are very,
• 0:17
  very tricky, so we'll see how it all pans
• 0:20
  out. Um, a question about the expanding
• 0:23
  universe. Never had one of those before. Uh,
• 0:25
  a question about gravitons. Never had one of
• 0:28
  those before. Yes, we have. Uh, photons
• 0:31
  and weight shift. That's all coming up on
• 0:34
  this edition of space nuts. 15
• 0:37
  seconds.
• 0:37
  Professor Fred Watson: Guidance is internal. 10,
• 0:40
  9. Ignition sequence start.
• 0:43
  Space nuts. 5, 4, 3. 2. 1, 2,
• 0:46
  3, 4, 5, 5, 4, 3, 2, 1.
• 0:49
  Andrew Dunkley: Space nuts. Astronauts report it feels
• 0:52
  good. And joining us once more to
• 0:54
  unravel all of that, or maybe ravel it
• 0:57
  up even more, is Professor Fred Watson
• 0:59
  Watson, astronomer at, uh, large. Hello,
• 1:00
  Fred Watson.
• 1:01
  Professor Fred Watson: Hello, Andrew. I do feel pretty ravelled at
• 1:04
  the moment.
• 1:05
  Andrew Dunkley: Yeah, look, we have got some tricky
• 1:07
  questions, but before we get to those, uh,
• 1:10
  we've received a note from Rennie in
• 1:13
  California.
• 1:13
  Uh, Rennie quite regularly sends questions
• 1:16
  into us, but he sent us a really lovely note
• 1:19
  which I want to share. Uh, he says no
• 1:22
  questions today, just to thank you. I try to
• 1:24
  absorb as much information as I can listening
• 1:26
  to your podcast. And when I'm engaged in a
• 1:28
  convers conversation with my two grandsons
• 1:31
  aged 15 and 12, I try to excite
• 1:33
  them and get them to think about our place in
• 1:36
  the universe and how it behaves. Now it's
• 1:39
  paying off with the announcement that my
• 1:41
  older grandson wants to carry on in college
• 1:44
  with some form of education in astronomy
• 1:47
  or particle physics. Thank you for paying
• 1:50
  it forward, Renny. Isn't that lovely?
• 1:52
  Professor Fred Watson: Yeah, that's great. Absolutely great.
• 1:54
  Andrew Dunkley: Uh, I love it when we get feedback from
• 1:56
  people that, that become inspired
• 2:00
  despite us.
• 2:04
  No, I mean, it's fantastic.
• 2:05
  Professor Fred Watson: It is.
• 2:05
  Andrew Dunkley: I'm really, really pleased. Really pleased.
• 2:07
  So, um, pass on our regards, Rennie, to your
• 2:10
  boys or, uh, your grandsons, um, and wish
• 2:12
  them well and. Yeah, look, just.
• 2:15
  I do the same thing with my grandson and
• 2:17
  three granddaughters. Um, I talk to them
• 2:20
  whenever there's something interesting to
• 2:22
  talk about, and there usually is, uh, in the
• 2:24
  astronomical world. And, um, I show
• 2:27
  them the images I take with the Telesco, and
• 2:29
  I've even had them outside looking up at the
• 2:32
  moon. And, um, yeah, it's captivating. Once,
• 2:35
  once they, you know, once you can convince
• 2:37
  them to actually get outside.
• 2:39
  Um, you know, the universe is their
• 2:42
  oyster. It's, uh, it's good
• 2:45
  stuff. So lovely to hear from you, Rennie.
• 2:47
  And that is really fabulous news.
• 2:50
  Are you ready for your first question,
• 2:51
  Fred Watson?
• 2:53
  Professor Fred Watson: Well, after a. Yes. After a build up like
• 2:55
  that, I guess we've got to tackle them,
• 2:56
  haven't we?
• 2:57
  Andrew Dunkley: Uh, we probably should.
• 2:58
  Professor Fred Watson: You're right, in a way. You know, the
• 3:00
  ultimate notes, I guess,
• 3:03
  is to provide that little bit of perhaps
• 3:06
  inspiration that might lead people to do
• 3:09
  things that might one day change the world.
• 3:11
  Who knows?
• 3:12
  Andrew Dunkley: Yep, you just don't know. You just don't
• 3:14
  know. Maybe that's our lot in life is to just
• 3:18
  try to inspire, uh, just a handful of people
• 3:20
  to pick up the baton, Fred Watson. Who knows?
• 3:24
  All right, question one. It's like a test,
• 3:27
  isn't it?
• 3:27
  Question one. Uh, if space is
• 3:30
  expanding faster than the speed of light,
• 3:32
  then in millions or billions of years from
• 3:35
  now, will our night sky be completely black
• 3:38
  or a completely black void? Um,
• 3:41
  uh, or completely black, devoid of
• 3:44
  all light except our local solar system. That
• 3:47
  comes from Clint. Uh, this is
• 3:50
  something that has come up occasionally and I
• 3:53
  think even in one of our most recent
• 3:55
  episodes, we were talking about the expansion
• 3:58
  of the universe and its significance. And,
• 4:00
  and I think in our Q and A episode, someone
• 4:02
  asked about the expansion of the universe.
• 4:05
  Um, so here it is again.
• 4:08
  Um, we are, ah,
• 4:11
  expanding, and it's
• 4:13
  expanding at an accelerating rate. Although
• 4:16
  it's debatable whether or not that
• 4:17
  acceleration is actually as m. Significant
• 4:20
  as it was. That is a
• 4:23
  separate debate. Um, but I think it's pretty
• 4:26
  clear that in the long distant future
• 4:29
  of this universe, it will become a black
• 4:32
  void, won't it?
• 4:34
  Professor Fred Watson: Uh, yes. So the answer to Clint's question
• 4:37
  is yes.
• 4:38
  Andrew Dunkley: Okay, question
• 4:41
  Professor Fred Watson: no. Exactly. As you said, um,
• 4:43
  if you've got, um. So
• 4:47
  when you say the universe is expanding more
• 4:50
  than the speed of light, you've got to be a
• 4:52
  bit specific because really what you're
• 4:54
  talking about is objects within
• 4:57
  the universe which are being carried along by
• 4:59
  the expansion of the universe. And so,
• 5:03
  uh, there will be, at a certain
• 5:05
  distance from us now,
• 5:08
  objects whose, what we call the recession
• 5:10
  velocity is faster than the speed of light,
• 5:13
  but they're actually, they're beyond
• 5:16
  the wall that we can't see beyond anyway,
• 5:18
  which is the cosmic microwave background
• 5:20
  radiation. But you can imagine as the
• 5:22
  expansion continues to accelerate, and you're
• 5:25
  right, it is still thought to be
• 5:27
  accelerating. We just don't quite know
• 5:29
  whether that acceleration is a constant.
• 5:31
  That's the thing you were alluding
• 5:34
  to because there's some evidence that
• 5:37
  maybe the acceleration is reducing,
• 5:40
  but nevertheless it's still accelerating. So
• 5:42
  it's still getting bigger, faster, uh, all
• 5:45
  the time. And so what that would do,
• 5:48
  um, you can, you can sort of
• 5:51
  imagine in your head what this situation
• 5:53
  would lead to. It means that the,
• 5:56
  the, the sort of black horizon, the horizon
• 5:59
  which is where light can never get to you
• 6:02
  because it's being carried away. The objects
• 6:04
  are being carried away faster than the speed
• 6:05
  of light. That black horizon will, will
• 6:08
  approach, um, it'll get nearer
• 6:11
  as the universe's expansion continues to
• 6:14
  accelerate. So eventually you can imagine
• 6:16
  that maybe you would see just
• 6:19
  the other galaxies in the Local Group, uh,
• 6:22
  which is Andromeda and the, uh, triangular
• 6:24
  whirlpool galaxy and things like that. But
• 6:27
  eventually, yeah, it might just be
• 6:30
  objects in our own solar system, uh,
• 6:33
  which makes astronomy a little bit of a.
• 6:36
  Boring. Yeah.
• 6:38
  Yeah.
• 6:39
  Andrew Dunkley: Well, let's go see what we can find. Oh,
• 6:41
  there's the moon.
• 6:41
  Professor Fred Watson: Yeah. Yeah. Oh, wait, it's gone.
• 6:46
  Andrew Dunkley: Well, it's moving away from us too.
• 6:48
  Professor Fred Watson: So it is rather slower than the speed of
• 6:50
  light. Yeah. Six centimetres a year.
• 6:52
  Andrew Dunkley: I can't imagine this is going to happen in an
• 6:54
  awful hurry, Fred Watson.
• 6:55
  Professor Fred Watson: No, it's not. It's very, very long way down
• 6:58
  the track. And of course, from our
• 6:59
  perspective here on, ah, Earth, long, uh,
• 7:01
  before anything like that takes place,
• 7:04
  um, we'll have been
• 7:07
  confronted by the expansion of the sun
• 7:09
  itself, um, as it turns into
• 7:12
  a red giant star.
• 7:14
  Andrew Dunkley: Yeah. Who knows where we'll be in the
• 7:16
  universe by then. We might have moved out
• 7:19
  into other parts of the galaxy by then if
• 7:21
  we've managed, um, to find some kind of
• 7:24
  propulsion system or learn how to fold
• 7:27
  space or whatever it is you need to do. Uh,
• 7:29
  maybe develop wormholes and be able
• 7:32
  to travel mega distances.
• 7:34
  Professor Fred Watson: Yeah. Fast. You're the person, you're the
• 7:37
  science fiction writer. You've got to tell us
• 7:39
  what it is we're going to do.
• 7:40
  Andrew Dunkley: Uh, I'm working, um, uh, on
• 7:44
  warp, uh, warp travel at the moment.
• 7:46
  Professor Fred Watson: Oh, good.
• 7:47
  Andrew Dunkley: In m. My. In my novels. So,
• 7:49
  yeah, I'm doing the final editing at this
• 7:52
  stage and it's, uh, it's the most horrible
• 7:55
  job.
• 7:56
  Professor Fred Watson: It is, isn't it? Yeah.
• 7:57
  Andrew Dunkley: Especially writing's fun.
• 7:59
  Professor Fred Watson: Yeah.
• 7:59
  Andrew Dunkley: But then you've got to fix all your blunders
• 8:01
  and you don't realise how really hopeless you
• 8:04
  are until you have
• 8:05
  Professor Fred Watson: to edit your own stuff.
• 8:07
  Andrew Dunkley: Yeah, yeah. I'd pay someone, but I can't
• 8:10
  afford it. It's not a, it's not a cheap
• 8:13
  thing to get Done book editing. Um,
• 8:16
  but anyway, uh, so the basic
• 8:18
  answer to Clint's question is yes, it's going
• 8:21
  to happen. Uh, there will be complete black
• 8:24
  nothingness, um,
• 8:27
  in a matter of about three weeks time, or
• 8:29
  could be three gazillion years time.
• 8:31
  Professor Fred Watson: I think the latter's more likely.
• 8:32
  Andrew Dunkley: More likely the latter. Thank you, Clint.
• 8:35
  Great to hear from you.
• 8:37
  Our next question comes from
• 8:40
  somebody whose name I forgot to write down.
• 8:42
  Uh, no, it didn't. It comes from, uh, Alan.
• 8:44
  Now, this is a pretty big question, so I'll
• 8:47
  just go straight through it and we can figure
• 8:48
  all out the rest out later. Uh, I know you
• 8:51
  want audio questions, but you know how they
• 8:54
  say you have a face made for radio? I've got
• 8:57
  one of those. Well, uh, I have a voice made
• 9:00
  for text. That's very
• 9:03
  good. I, um, hope it's not true. Uh, I
• 9:05
  discovered space nuts more than a year ago
• 9:08
  and have listened to your entire back
• 9:10
  catalogue.
• 9:11
  Professor Fred Watson: Wow.
• 9:12
  Andrew Dunkley: Wow. Get a job. No. Fantastic. Thank
• 9:15
  you. Uh, still listening and have not lost my
• 9:18
  mind yet.
• 9:19
  Professor Fred Watson: Wow.
• 9:20
  Andrew Dunkley: That's a record.
• 9:21
  Uh, here's something that's been bothering me
• 9:22
  for, uh, some months. Some physicists
• 9:25
  don't believe relativity, uh, when it says
• 9:28
  that gravity is not a force. Also, they
• 9:30
  believe that all forces are conveyed by
• 9:32
  particles. To unify gravity with other
• 9:35
  forces, they postulate the graviton to be
• 9:38
  that particle for gravity. It's said that
• 9:41
  nothing escapes a black hole, but actually
• 9:42
  gravity does. If gravitons exist
• 9:46
  and convey the force of gravity, then they
• 9:49
  escape black holes. So they are not affected
• 9:51
  by gravity. That means they do not affect
• 9:54
  each other. We know gravity does affect all
• 9:57
  massive particles and photons, massless
• 9:59
  particles that convey the electromagnetic
• 10:01
  force. I don't know if gravitons affect other
• 10:04
  massless particles. This is the interesting
• 10:06
  part. If f equals gm 1 m
• 10:09
  2 divided by d squared is
• 10:12
  the complete calculation for the force
• 10:15
  of gravity, no modifications introduced by
• 10:17
  relativity or quantum physics, then gravitons
• 10:20
  are not affected by anything. So gravitons
• 10:23
  affect every particle except gravitons and
• 10:25
  are not affected by anything. So is
• 10:28
  an asymmetry that breaks
• 10:32
  conservation, uh, of energy and momentum. My
• 10:34
  question is. Here it is. Why do some
• 10:37
  physicists still believe in
• 10:40
  gravitons? That comes from Alan in San
• 10:42
  Antonio, Texas. Boy, Alan, you've put a lot
• 10:45
  of thought into that. You really have.
• 10:47
  Professor Fred Watson: Yeah. And these are questions that are right
• 10:49
  on money as well. Yeah. Uh, especially the
• 10:51
  last one. Why do physicists believe in
• 10:54
  gravitons? I think most physicists probably
• 10:56
  do. Uh, Alan, because
• 10:58
  um, we know that gravity is a fundamental
• 11:01
  force and all the other fundamental forces
• 11:03
  have their subatomic particles,
• 11:06
  uh, which are basically
• 11:09
  um, um,
• 11:13
  particles that can. That sort of what we
• 11:16
  call, we call them bosons. They're what, they
• 11:18
  carry a field in a way. And the field is
• 11:21
  another way of looking at how a uh,
• 11:24
  force works. I didn't
• 11:27
  phrase that very well, but uh, that's why
• 11:30
  some physicists believe in gravitons. We've
• 11:33
  never found them. We don't have a particle
• 11:35
  physics theory of gravity. Uh, so we don't
• 11:38
  know that they exist. But I think most
• 11:40
  physicists would assume that they exist.
• 11:44
  And so uh, that
• 11:46
  first um, conundrum
• 11:51
  that you mentioned,
• 11:53
  if nothing escapes a black hole, well,
• 11:56
  gravity does. And so if
• 11:58
  gravitons exist and convey the force of
• 12:00
  gravity, then they escape black holes. So
• 12:03
  they're not affected by gravity. That means
• 12:05
  they do not affect each other. But in
• 12:08
  fact, um, uh,
• 12:11
  the bottom line with black holes it's
• 12:14
  quite complicated. Uh, but you
• 12:17
  don't have gravitons escaping
• 12:20
  from the black hole. Uh,
• 12:23
  the way people who know a lot more about
• 12:26
  these things than me, uh, the way they
• 12:28
  envisage this is that the gravitational
• 12:31
  field of the black hole is a kind
• 12:34
  of fossilised one that was
• 12:37
  established before the collapse
• 12:40
  into uh, a black hole.
• 12:44
  Or, and here's another way of looking at it.
• 12:49
  This really, you're gonna think, um, Alan,
• 12:51
  this is a cop out, but this is the way the
• 12:54
  physicists see it. Uh, the,
• 12:57
  the gravitational field of black hole
• 12:59
  basically uh, includes
• 13:02
  something called virtual gravitons.
• 13:05
  Uh, and so that sort of ties in with the fact
• 13:08
  that the, the gravitational field is a
• 13:10
  fossilised footprint, if I can put it that
• 13:13
  way. Um, the
• 13:16
  virtual gravitons, uh, are an
• 13:18
  embodiment of that, but they don't
• 13:21
  necessarily obey the
• 13:23
  normal laws of physics.
• 13:28
  So
• 13:30
  uh,
• 13:34
  basically what you've got here, and
• 13:37
  I think, um, the
• 13:40
  physicists who look at this problem probably
• 13:42
  just automatically drop into the two
• 13:45
  camps of relativist people who
• 13:48
  are ah, experts in general relativity. That's
• 13:51
  Einstein's theory of gravity that says, yes,
• 13:53
  um, gravity is not a force, it's just a
• 13:56
  distortion of space. Uh, and the quantum
• 13:58
  mechanics people who look at it from the
• 14:01
  perspective of gravitons.
• 14:05
  Um, and so yeah, the virtual particles,
• 14:08
  uh, the quantum mechanics
• 14:11
  person's answer to this,
• 14:15
  uh, they're basically
• 14:17
  just mathematical constructs, uh, in a
• 14:20
  quantum field. And so they don't have to
• 14:23
  obey speed limits or anything like that, or
• 14:26
  even don't have to worry about the event
• 14:28
  horizon so they can continually
• 14:32
  basically, uh, keep the gravitational force
• 14:34
  there without actually being
• 14:37
  trapped by it. I think that's the way
• 14:40
  physicists look at it.
• 14:43
  Andrew Dunkley: Uh, all that says to me is
• 14:48
  something. It's still a big mystery. There
• 14:50
  are so many different theories behind
• 14:52
  gravity, and we really don't know what it is.
• 14:56
  We know what it is, but we don't know why it
• 14:58
  is.
• 14:58
  Professor Fred Watson: Well, no. So all we know about
• 15:01
  gravity is the way it behaves. Um,
• 15:04
  we really don't know what it is. And in a
• 15:07
  way, Alan's question is well posed
• 15:10
  because it could end up that it's something
• 15:13
  different and there aren't gravitons.
• 15:15
  Um, and, uh, that's why we haven't found
• 15:18
  them, because they're not there. Um,
• 15:22
  it's fascinating. I mean, in a sense,
• 15:25
  uh, gravitons are along the same line as the
• 15:28
  hypothetical dark matter particles. We know,
• 15:31
  um, dark matter is real. We know it's
• 15:34
  there. Uh, we assume it's subatomic
• 15:37
  particles. We've seen some recent works. Uh,
• 15:40
  work. Sorry. We've seen some recent work that
• 15:42
  suggests perhaps they're not, um,
• 15:45
  perhaps it's not subatomic particles, but
• 15:47
  primordial black holes, which can be very
• 15:49
  small and very difficult to detect. Uh, which
• 15:52
  takes us back to the, um, macho
• 15:55
  theory. Massive compact halo objects, the
• 15:57
  macho theory of dark matter, as distinct from
• 16:00
  the WIMP theory, the weakly interacting
• 16:01
  massive particles. I
• 16:04
  think gravitons almost fall into the same
• 16:07
  boat as dark matter particles in the sense
• 16:10
  that we haven't detected them. We hypothesise
• 16:12
  that they're there. We've built constructs
• 16:14
  like virtual gravitons that allow us to do
• 16:17
  that without going completely mad. Um,
• 16:19
  but, uh, at the moment, still, I think,
• 16:23
  uh, the door is wide open for all kinds of
• 16:25
  new ideas that might change our view
• 16:27
  completely.
• 16:28
  Andrew Dunkley: Yeah, I guess the day we crack it will
• 16:31
  go, uh. Yeah, I should have thought of that.
• 16:35
  Professor Fred Watson: Exactly. Well, Alan's already thought of it.
• 16:37
  Andrew Dunkley: Yeah.
• 16:38
  Professor Fred Watson: Yeah. In terms of, you know, what, what the
• 16:40
  conundrums are and why it is. Why it's so
• 16:43
  difficult. Yeah, it's a great question.
• 16:45
  Andrew Dunkley: I guess the question that comes from that is,
• 16:47
  does it have to be a particle? And the answer
• 16:49
  is no. Um, it doesn't, uh, have to be
• 16:52
  just because everything else is made of
• 16:54
  particles. So.
• 16:56
  Professor Fred Watson: Yes, that's right. I mean, it's.
• 16:59
  So what's called the standard model of
• 17:01
  subatomic particles is this
• 17:04
  group of 17 particles which we don't
• 17:07
  think can be broken down into Anything
• 17:09
  smaller. That's why they're called
• 17:10
  fundamental, um, and
• 17:13
  they account. Among them are, uh,
• 17:16
  the force, um, particles,
• 17:19
  um, electromagnetic, strong
• 17:22
  and weak nuclear forces, um,
• 17:26
  uh, which we know about. Gravity is just
• 17:29
  assumed to be, uh, a fundamental force
• 17:32
  with its fundamental particle because it
• 17:34
  behaves in every other way. It behaves like
• 17:37
  the other ones do. Uh, but we just haven't
• 17:39
  managed to pinpoint the particle itself.
• 17:43
  There you go.
• 17:43
  Andrew Dunkley: Ah, Alan, you've kind of, um, put
• 17:46
  your thumb on one of the big mysteries of the
• 17:49
  universe and expected us to have an answer.
• 17:53
  Uh, no, it's just
• 17:56
  one of those great big, um, question marks in
• 17:59
  space. If you look up, you can see a giant
• 18:00
  question mark in space. That's gravity.
• 18:04
  Professor Fred Watson: That's right, yeah.
• 18:06
  Andrew Dunkley: Uh, whether or not there are gravitons, the
• 18:08
  debate remains. Thank, uh, you, Alan, for the
• 18:11
  question. This is Space Nuts Andrew Dunkley
• 18:14
  here with Professor Fred Watson Watson.
• 18:18
  Professor Fred Watson: I believe that this nation should commit
• 18:20
  Andrew Dunkley: itself to achieving the goal
• 18:23
  before this decade is out, of landing a
• 18:26
  man
• 18:26
  Professor Fred Watson: on the moon and returning him safely to the
• 18:28
  Earth.
• 18:28
  Andrew Dunkley: Beast nuts, Fred Watson.
• 18:30
  Our next question comes from, uh,
• 18:33
  somebody else who's thinking particles. I
• 18:35
  spend a lot of time thinking about
• 18:38
  photons and have, uh, so many questions about
• 18:41
  them. Uh, you know, I know
• 18:44
  this about Misty because, um, she's always
• 18:46
  walking around with a light bulb above her
• 18:48
  head. So that explains that,
• 18:51
  um, photons are really weird to understand.
• 18:54
  I'm curious to know if there are any
• 18:56
  fundamental particles that do not have a
• 18:59
  wave function. And then is it possible
• 19:02
  to detect a particle or photon that does not
• 19:05
  have any properties of a wave?
• 19:08
  And the last part of the question. Is it
• 19:10
  possible for a photon or particle to have
• 19:13
  such a long wavelength that we don't have a
• 19:15
  detector big enough to pick it up? That's,
• 19:17
  uh, from Misty in Pennsylvania, one of our
• 19:19
  administrators on the Facebook PODC Ask
• 19:21
  Group. So, um, uh, thank you, Misty,
• 19:24
  for sending in a question. Nice to hear from
• 19:26
  you and beautiful part of the world,
• 19:28
  Pennsylvania. Got to drive through that last
• 19:30
  year. And, uh, yeah, it is
• 19:33
  absolutely lovely in summer. Don't
• 19:36
  think I want to be there in winter.
• 19:41
  Nevertheless. Okay, so, um,
• 19:44
  photons. Yeah. What can we talk? What
• 19:47
  can you tell us about? Are there any
• 19:50
  particles that don't have wavelengths? That's
• 19:52
  an interest question.
• 19:53
  Professor Fred Watson: Yes. So that's M, more or less what
• 19:56
  it amounts to. So we see
• 19:59
  in quantum mechanics, uh,
• 20:02
  we see this fundamental thing that particles,
• 20:05
  m, uh, display the properties
• 20:08
  both of a particle and a wave. And so we
• 20:11
  call it a wave function. And as
• 20:14
  I understand it, and I Think, uh, quantum
• 20:16
  mechanics backs, uh, this up.
• 20:19
  Uh, there are no fundamental particles
• 20:23
  that don't have a wave function, so they
• 20:26
  all exhibit this wave particle
• 20:28
  duality.
• 20:30
  Andrew Dunkley: Um,
• 20:35
  Professor Fred Watson: It is, uh,
• 20:38
  I guess, you know, the way that,
• 20:41
  um, particle physicists think about
• 20:43
  these things are uh, a little bit different
• 20:47
  from the way we might interpret it. So when I
• 20:50
  think of the wave particle duality,
• 20:53
  my mind immediately goes to the photon,
• 20:56
  um, which, um, Misty's already mentioned.
• 21:00
  Uh, yes, we understand
• 21:03
  photons as particles because we see the
• 21:05
  photoelectric effect, which insists that
• 21:08
  they've got to be particles because you get
• 21:10
  basically quantized amounts of energy out of
• 21:13
  them. But then when I think about the waves,
• 21:15
  I think about things like polarisation,
• 21:19
  uh, where you've got waves that are
• 21:21
  oscillating in different directions. I think
• 21:23
  we talked about that a couple of episodes
• 21:24
  ago, we did, in the mapping of the magnetic
• 21:27
  fields of the galaxy of the universe. Um, and
• 21:30
  so I always think about waves vibrating
• 21:32
  through a median. But,
• 21:35
  um, the physicists
• 21:38
  kind of combine those two ideas
• 21:42
  and, uh, think in terms of, uh, something
• 21:45
  it's usually called quantized
• 21:48
  excitations of underlying
• 21:51
  fields. So
• 21:53
  that's to say that, um,
• 21:56
  it kind of mixes both relativity and
• 21:59
  quantum physics here because the
• 22:02
  underlying field is what?
• 22:05
  Um, it's the sort of,
• 22:08
  if I can put it that way, the background
• 22:10
  canvas on which the information
• 22:13
  is superimposed and the particle
• 22:16
  is a bit of that background canvas that is
• 22:19
  excited to vibrate and
• 22:22
  give you a wave, but it's
• 22:24
  excited in a way that is quantized. That
• 22:27
  means there isn't an
• 22:30
  infinite number of different excitations
• 22:33
  that can be set up.
• 22:36
  They're specific numbers,
• 22:39
  which means you get specific wavelengths
• 22:42
  from the excitation. So it is all a
• 22:44
  mix of, of
• 22:47
  particles and waves, but it kind of brings
• 22:50
  it together and once you think of it in those
• 22:52
  terms, uh, then
• 22:56
  it becomes clear that you can't have a
• 22:58
  particle without its wave function.
• 23:00
  Andrew Dunkley: Which kind of writes off her second question.
• 23:03
  If there's, um, a long enough wavelength that
• 23:06
  we haven't got the equipment to detect it.
• 23:08
  Professor Fred Watson: Um, no, I don't think it does
• 23:11
  because I think, um,
• 23:14
  I mean we, you know, we. In, in
• 23:17
  a way the ultra low
• 23:20
  frequency radio waves are a bit like that,
• 23:23
  uh, because they are,
• 23:27
  uh. Some of them have got a wavelength bigger
• 23:29
  than the Earth. And
• 23:31
  so how do you detect that? Well, you've got
• 23:34
  to have a spacecraft that's got the other end
• 23:36
  of the aerial on it, you know, that sort of
• 23:38
  thing. Um, there's also,
• 23:42
  uh. What was I going to say,
• 23:45
  um, yeah, we know that there are
• 23:48
  gravitational waves that have got
• 23:51
  wavelengths measured in light years. Uh,
• 23:54
  I think the gravitational
• 23:57
  properties of the Big Bang. So the
• 24:00
  gravitational waves that were set up by the
• 24:02
  Big Bang are extremely long
• 24:05
  wavelength. I think I've got that the right
• 24:07
  way around. Um,
• 24:10
  it's so, uh. And we, you know, there are
• 24:12
  ones that we don't have normal,
• 24:16
  everyday ways of detecting them. There are
• 24:18
  subtleties because you expect some of these
• 24:20
  waves to be polarised. And that, I think,
• 24:22
  gives you an insight into it. But, yeah,
• 24:24
  it's, uh. Look, it is a good question.
• 24:28
  Uh, and I, uh, think, um, once again,
• 24:31
  mist is thinking outside the box. Uh,
• 24:34
  no particles without their wave
• 24:36
  function, because a particle is an
• 24:39
  excitation of the underlying field, a
• 24:42
  quantized excitation of the underlying field.
• 24:45
  Andrew Dunkley: So it is possible we cannot detect certain
• 24:47
  wavelengths because they're too big, but they
• 24:49
  still exist.
• 24:50
  Professor Fred Watson: I think that's right, yes.
• 24:51
  Andrew Dunkley: Yeah. All right. What about gravitons? Do you
• 24:54
  reckon they have a wavelength?
• 24:55
  Professor Fred Watson: Well, yes, they do. That's the thing. Um, if
• 24:57
  they exist, yes. Uh, because, um,
• 25:01
  uh, we've got gravitational waves. So the
• 25:03
  wave particle duality works both ways. If
• 25:06
  you've got a wave, you've got a particle.
• 25:07
  Andrew Dunkley: There you go. Uh, good one. Thanks,
• 25:10
  Misty. Hope all is well in Pennsylvania.
• 25:16
  Three, two, one.
• 25:18
  Professor Fred Watson: Space nuts.
• 25:20
  Andrew Dunkley: And our final question, uh, comes from
• 25:23
  another one of our regular contributors,
• 25:25
  Casey in Colorado. What does it feel
• 25:28
  like to go from weightlessness to normal
• 25:30
  gravity for astronauts when returning to
• 25:33
  Earth? I think it would depend
• 25:36
  on how long you've been up there and, uh,
• 25:38
  whether or not you've actually bothered to
• 25:40
  use the treadmill.
• 25:43
  Professor Fred Watson: Well, that's right. The treadmill is all
• 25:45
  about keeping up your muscle strength.
• 25:46
  Andrew Dunkley: Exactly. Um, because once you're out there,
• 25:49
  your muscles immediately start to wither. Uh,
• 25:52
  they do.
• 25:52
  Professor Fred Watson: And you don't really have anything against
• 25:55
  which to push to keep them,
• 25:58
  you know, keep them going, other than the.
• 26:00
  The, um, torture equipment that
• 26:03
  NASA and Roscosmos provide on their space
• 26:06
  station.
• 26:06
  Andrew Dunkley: I think on Space Lab, they didn't have a
• 26:08
  treadmill. They had a running track that ran
• 26:10
  around the inside of
• 26:14
  wall of, uh, Skylab, I think. And
• 26:17
  so I've seen footage of astronauts actually
• 26:20
  running in a circle around the
• 26:23
  interior of Skylab.
• 26:25
  Professor Fred Watson: So they're keeping themselves, um, running
• 26:28
  just by the centrifugal force that they're
• 26:30
  setting up. Yeah, yeah, yeah. That's
• 26:32
  interesting. I didn't know that. That's, uh.
• 26:34
  Andrew Dunkley: Yeah, I'm sure that if you had online, you'd
• 26:37
  find Footage of it. I. I strongly remember
• 26:40
  that M. I saw it on the news one day and
• 26:42
  thought, wow, how did they do that? Well,
• 26:44
  there's no gravity, duh. Uh,
• 26:47
  Professor Fred Watson: yeah. Um,
• 26:50
  wasn't there something like that in 2001 A
• 26:53
  Space Odyssey? I think there was. Could have
• 26:55
  been.
• 26:55
  Andrew Dunkley: I think I watched that very recently.
• 26:58
  I just thought I really wanted to watch it
• 27:00
  again. But, um, I fell asleep. But
• 27:02
  it's very late. Judy had gone to bed, and I
• 27:04
  thought, oh, I might just start this. Uh,
• 27:07
  yeah, I was gone.
• 27:11
  Um, what was the question? Oh, uh, what's the
• 27:13
  feel like? I also remember seeing
• 27:16
  footage of cosmonauts, uh, coming back
• 27:19
  from very long haul time in space.
• 27:23
  And they'd get them out of the capsule once
• 27:25
  they came back to Earth and they couldn't
• 27:27
  stand up.
• 27:27
  Professor Fred Watson: Couldn't stand up. Yeah. I've seen similar
• 27:29
  things and. Well, you know, even with the
• 27:32
  exercise that the Artemis II crew
• 27:35
  were doing, they were a little bit wobbly
• 27:38
  when they got out of the spacecraft. And we
• 27:40
  all saw them going across the deck of the,
• 27:44
  uh, recovery ship. Uh,
• 27:47
  so I think how wobbly you are probably
• 27:49
  depends on just how much effort you've put
• 27:51
  into keeping up your muscle strength. So I
• 27:53
  think that's the key thing that Casey
• 27:57
  might be thinking of. Um, exactly. As
• 28:00
  you've said, your muscles go to waste very
• 28:02
  quickly. Uh, and if you. You don't
• 28:05
  exercise, then you're going to be in big
• 28:06
  trouble. You simply would not be able to
• 28:08
  walk. Um, so quite a
• 28:11
  significant, uh, thing. Ah. Which would also,
• 28:14
  of course, depend on how long you've been in
• 28:16
  space, how long you've been weightless.
• 28:17
  Andrew Dunkley: And the other thing they might suffer from is
• 28:20
  fatigue because they have
• 28:23
  to work so much harder to achieve the same
• 28:26
  mobility as they were used to. When they had
• 28:29
  full muscle strength, they'd get
• 28:32
  very tired very fast. I think,
• 28:35
  all jokes aside, I think the,
• 28:38
  um, everyday person,
• 28:41
  uh, who's been through, um,
• 28:43
  immunotherapy or some
• 28:46
  form of, um, um, um,
• 28:49
  inhibitor for, um,
• 28:53
  testosterone, for example, for cancer
• 28:56
  treatment or something like that, that
• 28:58
  has the same effect on your muscles. Muscle
• 29:01
  wastage. When you stop producing testosterone
• 29:04
  as a male, your muscles
• 29:07
  actually do fade away. And you've got to do
• 29:09
  exercise to keep. Like astronauts, you've got
• 29:12
  to keep your exercise up to keep your muscles
• 29:14
  in trim, but it
• 29:17
  does slow you down. Um, and case in
• 29:20
  point, I did have that sort of treatment for
• 29:22
  my prostate cancer. And for six months
• 29:25
  I went into basically the
• 29:28
  equivalent to menopause. I had muscle
• 29:30
  wastage. Um, I kept up my
• 29:32
  exercise, but it wasn't enough. And I
• 29:35
  had a situation where I'd go out and play
• 29:38
  golf. I lost 40 yards on
• 29:40
  shots simply because my muscles had wasted
• 29:43
  away. And it's probably taken a year to get
• 29:46
  it all back.
• 29:47
  Professor Fred Watson: Yeah, interesting.
• 29:48
  Andrew Dunkley: Yeah. Um, it would be the same effect for an
• 29:51
  astronaut on it. Exactly the same. Different,
• 29:53
  different, you know, different mechanism.
• 29:56
  Mechanism, but same effect.
• 29:59
  Um, and. And yet the
• 30:01
  other thing that they'd probably have to deal
• 30:03
  with is some, some of them have very
• 30:05
  significant health effects from, from
• 30:08
  being in zero G and you come back to Earth.
• 30:10
  Like we had a, um, didn't. Wasn't there an
• 30:13
  astronaut recently who was temporarily
• 30:15
  blinded from,
• 30:18
  from zero G? And there's all sorts of
• 30:21
  things that um, they can suffer from. And
• 30:24
  a lot of the time when they come back to
• 30:26
  Earth, it does fix itself because you're back
• 30:28
  in your normal environment. But when you're
• 30:31
  out there orbiting or going to the moon and
• 30:33
  back, it is not a human environment.
• 30:36
  Professor Fred Watson: That's not normal. Yeah, so it was an
• 30:39
  evacuation the uh, beginning of the year, I
• 30:42
  think it was, that we only really found out a
• 30:44
  few snippets about not very long ago.
• 30:47
  And I can't remember what the details were
• 30:50
  because my brain's atrophy because of
• 30:54
  old age.
• 30:56
  Andrew Dunkley: Yes, indeed. But, uh, there
• 30:59
  would be various levels of, um,
• 31:02
  dysfunction as a consequence of spending time
• 31:04
  in space. It would be a
• 31:07
  person to person variable.
• 31:10
  Um, it's not a one size
• 31:13
  fits all situation. Some people who'd come
• 31:15
  back probably not feel anything. But if, um,
• 31:18
  if you're up there long enough. Yeah, it's
• 31:20
  going to have a big impact on you.
• 31:22
  Professor Fred Watson: Yes, indeed.
• 31:24
  Andrew Dunkley: Thank you so much for the question, Kasey. I
• 31:26
  hope we covered it
• 31:29
  reasonably well. Um, anyway,
• 31:32
  uh, in the not too distant future, I'm pretty
• 31:34
  sure there'll be so many people going in and
• 31:36
  out of space, they'll come up with ways of
• 31:38
  dealing with it. Who knows? And
• 31:41
  I think that brings us to the end.
• 31:42
  Don't forget, if you've got, uh, questions
• 31:44
  for us or observations or comments or
• 31:47
  whatever you like, you can go to our website,
• 31:49
  send it to us in a text or audio
• 31:51
  format@spacenuts
• 31:53
  IO or
• 31:55
  spacenutspodcast.com
• 31:58
  and just click on the little ama button at
• 32:01
  the top that stands for Ask me Anything. And
• 32:04
  um, you can send it through. Don't forget to
• 32:07
  tell us who you are or where you're from.
• 32:11
  And Fred Watson, that's it. Thanks so much
• 32:13
  for answering those. That was a tough batch
• 32:15
  today.
• 32:17
  Professor Fred Watson: Great questions though. Well done. To all our
• 32:19
  listeners for what they do in terms
• 32:22
  of, uh, thinking through a lot of these
• 32:24
  issues. It's great.
• 32:25
  Andrew Dunkley: Very good. All right, we'll catch you real
• 32:27
  soon. Fred Watson, thanks so much.
• 32:28
  Professor Fred Watson: Looking forward to it. Thanks, Andrew.
• 32:30
  Andrew Dunkley: Professor Fred Watson Watson, astronomer at
• 32:32
  large. And thanks to Huw in the studio, who
• 32:34
  couldn't be with us today because, um,
• 32:36
  there was, um, so much going on with
• 32:39
  gravitons and weightlessness, he just
• 32:42
  decided to float away. And from me,
• 32:45
  Andrew Dunkley. Thanks for your company.
• 32:46
  We'll catch you on the next episode of
• 32:47
  SpaceNuts real soon.
• 32:48
  Professor Fred Watson: Soon.
• 32:49
  Andrew Dunkley: Bye. Bye. You've been listening
• 32:51
  to the Space Nuts podcast,
• 32:55
  available at Apple Podcasts, Spotify,
• 32:58
  iHeartRadio or your favourite podcast
• 33:00
  player. You can also stream on
• 33:02
  demand@bytes.com.
• 33:04
  Professor Fred Watson: this has been another quality podcast
• 33:06
  production from bytes.com.