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Cosmic Queries: Weighty Matters, Stellar Ages & Moonless Earth Scenarios · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Andrew Dunkley: Hello again and thank you for joining us.
• 0:02
  This is a Q and A edition of Space Nuts. This
• 0:04
  is where we stand in a queue and go,
• 0:07
  ah. Or not. Um,
• 0:11
  no, it's where we answer audience questions.
• 0:12
  We've got questions today about weight
• 0:15
  variations on Earth, depending on where you
• 0:17
  are. Um, I know we've been down that road
• 0:20
  before, but, um, we're going to do it again.
• 0:22
  Uh, the age of the solar system has been
• 0:25
  brought up again. Visiting, uh, another star.
• 0:28
  Would we be able to do that anytime soon?
• 0:32
  And Earth, uh, minus the moon. A what if
• 0:34
  question that we have done a trillion times.
• 0:37
  But, um, why not? Let's
• 0:39
  reroute to that little, um, what if
• 0:42
  scenario. That's all coming up on this
• 0:44
  edition of space nuts.
• 0:46
  Professor Fred Watson: 15 seconds. Guidance is internal.
• 0:48
  10, 9. Ignition
• 0:51
  sequence start.
• 0:52
  Professor Fred Watson: Space nuts.
• 0:53
  Professor Fred Watson: 5, 4, 3, 2. 1, 2, 3, 4,
• 0:56
  5, 5, 4, 3, 2, 1.
• 0:58
  Andrew Dunkley: Space nuts.
• 0:59
  Professor Fred Watson: Astronauts report it feels good.
• 1:02
  Andrew Dunkley: And he's back again to solve all your
• 1:04
  riddles. It's Professor Fred Watson Watson,
• 1:06
  astronomer at large. Hello, Fred Watson.
• 1:07
  Professor Fred Watson: Hello, Andrew. I'm glad to be a
• 1:10
  riddle solver.
• 1:11
  Andrew Dunkley: Yes, it's a good thing to do, even when you
• 1:14
  can't. You can just pretend. That's what we
• 1:16
  do all the time. I like the Q and
• 1:19
  A edition. It gives us a chance to hear other
• 1:21
  voices from around the world who listen to
• 1:24
  us. And, um, sometimes we learn more about
• 1:26
  them than we expect to. Like, um, Andy the
• 1:29
  train driver in Sydney. And, uh, we've had
• 1:32
  a few over the years. Rusty from Donnybrook,
• 1:35
  one of our regular sender innerers. And,
• 1:38
  um, Sandy in Melbourne and,
• 1:40
  oh, gosh, um, and plenty
• 1:43
  of others. Plenty, uh, of others. And if I
• 1:46
  didn't name you, and I should have, I
• 1:47
  apologise. Martin. We should not, not mention
• 1:50
  Martin.
• 1:51
  Professor Fred Watson: We've got pilots as well.
• 1:53
  Andrew Dunkley: We have. We have Hannah.
• 1:54
  Professor Fred Watson: That's right.
• 1:55
  Andrew Dunkley: Haven't heard from her in ages, but I hope
• 1:57
  she's well. Now, um, let's,
• 2:00
  uh, maybe get to our first question.
• 2:01
  Fred Watson.
• 2:02
  This comes from dj.
• 2:05
  DJ: Hi, guys. DJ from
• 2:07
  Indianapolis, Indiana, usa.
• 2:12
  You, in a recent podcast,
• 2:14
  talked about how if
• 2:17
  a person weighed a hundred kilogrammes
• 2:20
  on the North Pole, that they would weigh
• 2:23
  99 at the equator. My question would
• 2:26
  be, if you were to take a submarine up to the
• 2:29
  North Pole, you pop up through the ice, you
• 2:31
  hop out with your bathroom scale,
• 2:35
  stand on the ice and it says you
• 2:38
  weigh 100 kilogrammes. You take that
• 2:41
  same scale, drive the sub down
• 2:44
  to, say, Ecuador, get out on the
• 2:46
  beach, put your bathroom scale down and now
• 2:49
  would it then say you weighed 99.
• 2:52
  Or are bathroom scales
• 2:55
  calibrated for,
• 2:58
  uh, Earth's gravity at,
• 3:01
  say, the equator? And it would say you
• 3:03
  weighed 99 at the north
• 3:06
  Pole too. Would you need
• 3:08
  scientific instruments to tell the
• 3:11
  difference? Or could a normal person with a
• 3:12
  normal scale tell that they
• 3:15
  weighed a kilogramme less at the pole than
• 3:18
  they do at the equator? Thanks, guys.
• 3:22
  Andrew Dunkley: All right, the first floor in. His question
• 3:24
  is, putting the scales on sand
• 3:27
  would probably completely mess him up. But
• 3:30
  look, we know we get the gist. Um,
• 3:32
  yeah. 100 kilogrammes on the North Pole. Same
• 3:35
  set of scales at the equator. Or
• 3:38
  Ecuador, 99 kilos. Does that sound about
• 3:41
  right?
• 3:41
  Professor Fred Watson: It is. It's perfectly right, yeah. Uh,
• 3:44
  and it would show up on the scale. I mean,
• 3:48
  bathroom scales are notoriously inaccurate.
• 3:52
  They're not accurate to 1%.
• 3:55
  Um, but, but if you did have a really
• 3:58
  accurate scale and you can get them, um,
• 4:01
  then it would show the difference. Uh, it
• 4:03
  would be 100 kilogrammes, uh, on the pole,
• 4:06
  99 at, uh, the equator.
• 4:09
  Um, and that's because what
• 4:12
  you're measuring your weight against is
• 4:15
  something that doesn't change with
• 4:17
  gravity, and that's the spring. Um, you know,
• 4:20
  you're standing on something that's spring
• 4:22
  loaded and the spring behaves the same. No
• 4:24
  matter what gravitational field you're in, it
• 4:26
  still exerts the same force force. And so it
• 4:29
  will feel less weight from you at the
• 4:32
  equator, uh, uh, than it does at, uh, the
• 4:34
  poles. Now,
• 4:37
  um, I think that's fairly common knowledge
• 4:40
  that that happens, that you weigh less.
• 4:43
  Probably most people don't realise that it is
• 4:45
  actually 1%. It's almost exactly 1%, which is
• 4:48
  a bit of a coincidence, uh, but it has
• 4:51
  four sources, uh, not just one.
• 4:54
  So the weight that
• 4:57
  you feel are determined, uh,
• 5:01
  by first of all, the Earth's gravity,
• 5:04
  which is a property of the planet.
• 5:06
  But then you've got the moon's, the sun's
• 5:09
  gravity as well, pulling on you and the
• 5:12
  moon's gravity too. And
• 5:15
  then the thing that I think most people think
• 5:16
  about is the centrifugal force, the fact that
• 5:19
  the Earth is rotating and that gravity gives
• 5:22
  you a centrifugal force that tends to lift
• 5:24
  you a little bit.
• 5:26
  Professor Fred Watson: Um,
• 5:28
  Professor Fred Watson: and that's the case when you look at the
• 5:30
  sun's gravity and the moon's gravity. They're
• 5:32
  basically very, very
• 5:35
  small, uh, and they tend to cancel out.
• 5:38
  Anyway, uh, the
• 5:40
  centrifugal force comes about
• 5:43
  because on the equator, you're travelling at
• 5:46
  1600 kilometres an hour, uh, eastwards,
• 5:50
  and that Motion, because it's in a
• 5:52
  curve, uh, has an acceleration
• 5:55
  represented which cancels out a little bit of
• 5:58
  the gravity. Uh, but the other one is
• 6:01
  the Earth's gravity itself is different.
• 6:04
  Even if the Earth was not rotating, there
• 6:06
  would still be a difference at uh, the
• 6:08
  equator, uh, uh, from the pole. And that's
• 6:11
  because the Earth, uh, is not a perfect
• 6:13
  sphere. It's what we call an oblate spheroid.
• 6:15
  It's slightly flattened. So you're, I can't
• 6:18
  remember how far it is, you're 30 kilometres
• 6:21
  away or something like that, further away at
• 6:23
  the equator, greater from the centre of the
• 6:25
  Earth, uh, uh, than you are,
• 6:27
  uh, the pole. Let me just, I can
• 6:30
  do this in my head. Uh, it's actually
• 6:34
  21 kilometres is the difference.
• 6:37
  You're 21 kilometres further from
• 6:40
  the centre of the Earth when you're on the
• 6:43
  equator than you are at the pole. And that
• 6:45
  means you're higher up until you feel
• 6:48
  slightly less gravity. And when you add that
• 6:50
  to the gravity change you get because of the
• 6:52
  Earth's rotation, it comes to basically 1%.
• 6:56
  Uh, so. Really? Yeah, quite, quite, um, um,
• 6:59
  a nice calculation and also
• 7:02
  quite a nice question from Vijay because
• 7:04
  uh, or DJ I didn't quite catch which.
• 7:07
  Uh, but good to hear from you in Indiana. Uh,
• 7:10
  and it's a well directed question, uh, but
• 7:13
  the answer is yes, you'd see on your bathroom
• 7:15
  scale if it was accurate enough.
• 7:16
  Andrew Dunkley: Yes, uh, we took some bathroom
• 7:19
  scales on a cruise ship once and um, yeah,
• 7:22
  don't use them at sea. I weighed everything
• 7:24
  from 60 to 190 kilos
• 7:27
  in a matter of seconds.
• 7:32
  Uh, it does remind me though of when I was a
• 7:34
  kid. My dad was a pharmacist for his, almost
• 7:37
  his entire career. And back then when
• 7:40
  you didn't have scales at home or you know,
• 7:43
  very few people did, you'd go down to the
• 7:45
  chemist, uh, and you'd put, uh,
• 7:48
  in Australia you'd put 20 cents in the slot
• 7:51
  and stand on the scales and it would give you
• 7:53
  an accurate weight. Wait, last time I used
• 7:55
  one of those I was 11 stone.
• 8:00
  Professor Fred Watson: Yes, things are moving.
• 8:01
  Andrew Dunkley: I still remember 11 stone. Now 11 stone,
• 8:05
  um, doesn't mean much anymore.
• 8:07
  Um, but I'll work it out.
• 8:10
  Equals kilos
• 8:13
  and the answer is 69.85 kilos.
• 8:16
  Well, I weigh a little bit more than that
• 8:18
  now.
• 8:19
  Professor Fred Watson: Probably not that much more.
• 8:21
  Andrew Dunkley: Um, about 15 kilos more.
• 8:26
  Professor Fred Watson: Yeah.
• 8:27
  Andrew Dunkley: 11 stone back in the day. Yes, I was quite
• 8:29
  proud of that. But uh, you don't see them
• 8:32
  anymore, do you, those uh, scales out in
• 8:35
  front of the pharmacies.
• 8:36
  Professor Fred Watson: They used to be. You found them on railway
• 8:39
  stations as well in Britain? I don't know
• 8:41
  why.
• 8:41
  Andrew Dunkley: Yeah, well, they used to have them at
• 8:43
  railway, uh, stations for weighing packages
• 8:45
  and things like that and post offices and
• 8:48
  things. Yeah, yeah, yeah.
• 8:51
  All right, dj, thanks for the question, but,
• 8:53
  yeah, it's true. If you were to take a
• 8:54
  submarine, pop up at the North Pole, put your
• 8:56
  scales down and weigh 100, then go to
• 8:59
  Ecuador and do the same thing, you'd weigh
• 9:02
  99.
• 9:04
  Um, now our next question, Fred Watson. Uh,
• 9:06
  it comes from Nick, uh, who is in
• 9:09
  Cambridge in the uk. He said Cambridge, the
• 9:12
  UK one, just so we didn't get confused with
• 9:14
  Cambridge in the United States. I assume
• 9:16
  there'd probably be more than two. Um, now
• 9:19
  he says, as you answered my previous question
• 9:22
  so eloquently, I came back for a second
• 9:24
  helping. We must have been rude. Wouldn't
• 9:26
  have been you, Fred Watson. Uh, the solar
• 9:29
  system is, uh, 4.6 ish billion
• 9:32
  years old, but it formed from, uh,
• 9:34
  material that is older. Are there any
• 9:37
  estimates for how much older this
• 9:40
  material is? And can this help us date any
• 9:43
  supernovae that may have generated
• 9:45
  it? Uh, or was the solar system formation
• 9:48
  process so energetic that it reset isotope
• 9:51
  ratios, uh, everywhere within the sun's
• 9:53
  sphere of influence, much like heating rocks
• 9:56
  above their Curie point, uh,
• 9:59
  resets isotropic ratios. Thank you for the
• 10:02
  enlightening enlightenment twice a
• 10:05
  week. Uh, it keeps me relatively sane, if you
• 10:07
  can believe it. Nick from Cambridge, the uk,
• 10:10
  one, uh, I like. It's a
• 10:13
  good question. A couple of questions in
• 10:15
  there. So, yeah, um, I
• 10:18
  like where he's going with this.
• 10:19
  Professor Fred Watson: And it's one. I, um, think it's fair to say
• 10:22
  that this is a question still on the front
• 10:25
  line of research, um, because
• 10:30
  when you look through the, you know, the
• 10:32
  astronomical literature, you find a lot of
• 10:34
  stuff about the
• 10:37
  solar nebula. The solar nebula is a cloud of
• 10:39
  gas and dust which, um,
• 10:42
  basically the solar system was born in,
• 10:45
  uh, by this process of gravitational
• 10:47
  collapse. It collapses under
• 10:50
  its own mass, um, and starts spinning and
• 10:53
  you, the spinning produces a disc. So you've
• 10:55
  got a hot ball of gas in the middle, which
• 10:58
  becomes the sun, and this disc of rocky
• 11:01
  material and gaseous material as well
• 11:03
  swirling around it, which is the, um,
• 11:05
  protoplanetary disc. Um, when you look at
• 11:08
  papers, they nearly always
• 11:12
  Professor Fred Watson: commenting, um,
• 11:14
  Professor Fred Watson: on the contents of the solar nebula.
• 11:18
  Just in terms of the mix of gases.
• 11:21
  It's mostly hydrogen and helium with a few
• 11:24
  pollutants, which are, uh, what eventually
• 11:26
  made the rocky planets and the likes of us.
• 11:29
  Um, but there's not that much work done on
• 11:32
  uh, exactly the question that uh,
• 11:35
  Nick is uh, asking. You know, can you
• 11:37
  identify what supernovae
• 11:41
  were? Uh, uh, the
• 11:44
  remnants of their supernovae
• 11:47
  explosions, uh, which
• 11:49
  include heavy elements as well as the
• 11:51
  hydrogen and helium. Can you identify the
• 11:54
  dates of those supernovae? Now I have a
• 11:57
  recollection of seeing some papers that
• 11:59
  refer to evidence
• 12:03
  in uh, meteoritic rock. I think uh,
• 12:06
  that uh, suggests that some of the material
• 12:09
  of the solar system dates from about 8
• 12:11
  billion years ago. Remembering that the age
• 12:13
  of the solar system is more or less 4.6
• 12:16
  billion years, exactly as Nick says. Um,
• 12:19
  and we know it actually a bit more accurately
• 12:21
  than that, but that's the easy number to
• 12:23
  remember. 4.6, 4.7 billion years.
• 12:26
  Uh, so yes we do know it formed from material
• 12:29
  that, that's older but I think it's turning
• 12:31
  out to be quite difficult
• 12:34
  science to actually detect that.
• 12:36
  Um, and that may be
• 12:40
  because of the second part of his question.
• 12:42
  Although I suspect that the
• 12:44
  isotope ratios were probably preserved
• 12:47
  rather than destroyed as per the
• 12:50
  Curie point. Um, I'm sorry, this
• 12:53
  sounds like a waffly answer but I haven't
• 12:55
  really been able to pin down much research on
• 12:57
  this. There was a spacecraft that
• 13:01
  was launched um, back in, I
• 13:04
  think about 2001 that
• 13:07
  uh, it was called Genesis and it was a
• 13:10
  NASA, uh, experiment and the idea was to
• 13:13
  catch particles of the solar wind and bring
• 13:16
  them back to Earth. And the solar wind
• 13:19
  is basically nuclei of gas,
• 13:22
  they're mostly hydrogen, but you can also
• 13:25
  detect any sort of pollutants. And in a
• 13:28
  way what you're trying to do there's is
• 13:31
  analyse remnants
• 13:34
  of the cloud of gas and dust that form
• 13:37
  the solar system. You're trying to analyse
• 13:39
  traces of that gas and dust. And
• 13:43
  it's uh, similar to what we do with comets.
• 13:45
  We try and analyse comets to death because we
• 13:47
  know they're pristine objects, they've never
• 13:49
  been hot, they're just samples of
• 13:52
  the solar nebula frozen
• 13:55
  onto dust crystals. Uh, but
• 13:58
  um, Genesis unfortunately had ah, a problem.
• 14:01
  Um, the capsule that was sending
• 14:04
  back this material actually um,
• 14:07
  the one of the parachutes didn't open and so
• 14:09
  it crashed at I think it was 200 kilometres
• 14:12
  an hour. It hit the Earth and broke.
• 14:15
  Um, so there was some contamination but I
• 14:17
  think there was some research done on it but
• 14:20
  I don't think they got to the real nub of the
• 14:21
  matter. What's the, what's the solar
• 14:24
  nebula made of? Um, I'll Keep looking
• 14:27
  at this because it is a really interesting
• 14:29
  one. And, um, um, you know, if we come
• 14:32
  across any more definitive papers, we might
• 14:35
  be able to give Nick a shout out later on.
• 14:38
  Andrew Dunkley: So he's dug up a mystery, basically.
• 14:40
  Professor Fred Watson: Yeah. He's come up with.
• 14:41
  Andrew Dunkley: Come up with something we can't quite grapple
• 14:44
  with.
• 14:44
  Professor Fred Watson: That's right. Although I think, as I said,
• 14:46
  you know, and unfortunately I've been able to
• 14:47
  find the papers that I've read where it does
• 14:50
  suggest that we've got evidence for
• 14:52
  supernovae in the past, which are, uh, maybe
• 14:55
  8 billion years ago, so nearly twice the age
• 14:58
  of the solar system. But supernovae in the
• 15:01
  environment that we are now in, um, which
• 15:04
  would have contributed to the makeup of the
• 15:06
  solar system? Good question.
• 15:08
  Andrew Dunkley: It is fascinating. Thank you, Nick. We'll get
• 15:11
  back to you shortly. This is Space Nuts with
• 15:14
  Andrew Dunkley and Professor Fred Watson
• 15:16
  Watson.
• 15:19
  Professor Fred Watson: Step off the land now.
• 15:22
  That's one small step for man,
• 15:28
  one triumph leap for mankind.
• 15:31
  Andrew Dunkley: Space Nuts.
• 15:32
  Professor Fred Watson: Yes.
• 15:32
  Andrew Dunkley: And you're listening to a Q A edition.
• 15:35
  And our, uh, next question comes from
• 15:38
  Keith.
• 15:39
  Keith: Hey, guys, this is Keith in
• 15:41
  Vancouver, Washington, usa,
• 15:45
  and I'm just curious about interstellar space
• 15:48
  travel. How long do you think it's going to
• 15:51
  take for a human to be able to reach
• 15:54
  another star? It
• 15:57
  seems fairly restrictive with
• 16:00
  the distances involved and
• 16:03
  you know, what kind of travel
• 16:06
  it would take, be it
• 16:11
  warp drive or
• 16:15
  laser sail. But any, uh, just
• 16:18
  curious what you guys think, how long it's
• 16:21
  going to take for us to get there and how
• 16:23
  realistic it's actually going to be if
• 16:25
  anything will ever come of it.
• 16:28
  Thanks, guys. Love the podcast.
• 16:31
  Andrew Dunkley: Thank you, Keith. Great to hear from you.
• 16:33
  There's another place that's not where we
• 16:35
  would normally think it was. Vancouver. Like
• 16:38
  you automatically go, oh, that's Canada. But
• 16:40
  no, he's in the U.S. version.
• 16:43
  Uh, yes, uh, but Keith, uh, that's a great
• 16:46
  question. Um, I suspect it'll be a
• 16:48
  spaceship before it is a human being
• 16:51
  going to another star system, or another
• 16:54
  star for that matter. Uh, the nearest one's
• 16:57
  what, Proxima Centauri, which is
• 16:59
  4.41 light years away. So,
• 17:03
  uh, using conventional engines, you're
• 17:05
  looking at a trip of over 6,000
• 17:08
  years.
• 17:09
  Professor Fred Watson: 60.
• 17:10
  Andrew Dunkley: 60,000 years. Yeah, yeah, yeah.
• 17:12
  Okay, well, you know, don't forget to take
• 17:14
  some eggs, uh, because
• 17:19
  they don't keep that long actually. But no,
• 17:21
  they don't. It's,
• 17:24
  it's a, ah, it's a difficult one and it sort
• 17:26
  of goes back to what we were saying in the
• 17:28
  previous episode with Elon Musk and, you
• 17:30
  know, getting, um, you know, shooting around
• 17:32
  all over the solar system, uh, or
• 17:35
  all over the galaxy in the. In, um.
• 17:38
  Professor Fred Watson: Um.
• 17:38
  Andrew Dunkley: It's. It's not probably a high priority
• 17:41
  at this stage and I, I think the day will
• 17:44
  come where we'll be able to go faster.
• 17:47
  But whether or not we can go fast enough to
• 17:50
  make a trip to Proxima Centauri,
• 17:53
  um, you know, reasonably quick,
• 17:56
  uh, like at 99%
• 17:59
  relativistic speed, it would
• 18:02
  still take you
• 18:05
  about three years, I think.
• 18:07
  Professor Fred Watson: Uh, well, it would. No, it must be more than
• 18:10
  that because.
• 18:10
  Andrew Dunkley: No, well, I'm talking. It'd take you
• 18:13
  five. I worked it out, actually.
• 18:16
  Professor Fred Watson: It would be. Yeah, at light speed, it takes
• 18:19
  you 4.3. 4.4 years.
• 18:22
  Andrew Dunkley: Yes.
• 18:23
  Professor Fred Watson: Uh, and it. But you're right, you've got to
• 18:26
  take
• 18:26
  Andrew Dunkley: into account time dilation.
• 18:28
  Professor Fred Watson: You do. You've got all of that thrown in as
• 18:30
  well.
• 18:31
  Professor Fred Watson: Yeah.
• 18:31
  Professor Fred Watson: Um, and, uh, it's.
• 18:34
  Yes, it's hard to envisage,
• 18:37
  um, I mentioned in our, uh, last episode
• 18:40
  something about some work I'd seen that
• 18:42
  suggested that light sails weren't going to
• 18:44
  be the answer for this. Because when you get
• 18:46
  to high enough speeds, you get this drag,
• 18:49
  uh, that actually slows you down and you've
• 18:52
  just got to put so much energy into your
• 18:55
  laser pointing at the light sails,
• 18:58
  uh, that, um, it really
• 19:02
  is probably not going to work very well.
• 19:07
  Perhaps the nearest we've got to
• 19:09
  seriously thinking about interstellar travel
• 19:12
  has been the. What was it? Breakthrough
• 19:16
  Starshot. Starshot, that's the one.
• 19:19
  That project, which was a
• 19:21
  feasibility study funded by
• 19:24
  a Russian billionaire whose name was on
• 19:27
  the tip of my tongue a minute ago, but has
• 19:29
  now disappeared, as names tend to do. Milner.
• 19:31
  Yuri Milner. That's his name.
• 19:33
  Andrew Dunkley: There he is.
• 19:34
  Professor Fred Watson: Yeah. Um,
• 19:36
  um. Breakthrough Starshot was feasibility
• 19:39
  study to see whether we could, within
• 19:42
  a kind of human lifetime, and I think they
• 19:45
  were thinking of 20 to 30 years, get a
• 19:48
  spacecraft to the vicinity of Proxima
• 19:50
  Centauri, the nearest star. Uh, yeah.
• 19:53
  Andrew Dunkley: Now, interestingly, while you were talking, I
• 19:55
  asked, uh, ChatGPT to work it out. And for
• 19:58
  people on Earth, at
• 20:00
  99%, uh, of light
• 20:03
  speed travelling from Earth to Proxima
• 20:05
  Centauri, it would be a, um,
• 20:08
  4.3 year journey to get there.
• 20:11
  However, when you take into account
• 20:14
  time dilation, which becomes significant,
• 20:17
  the people on board would only
• 20:20
  age 7 months is what it's
• 20:23
  saying. I think they're missing something.
• 20:26
  Professor Fred Watson: Yeah. In, uh, that calculation, um,
• 20:29
  it's probably not that
• 20:32
  far Off. Yeah, it might not be just
• 20:35
  thinking about.
• 20:37
  Andrew Dunkley: So the Earth perspective is a 4.3 year
• 20:40
  journey. The onboard travellers would
• 20:42
  experience seven months.
• 20:43
  Professor Fred Watson: It's critically dependent on how near the
• 20:45
  speed of light you get to.
• 20:47
  Andrew Dunkley: This uh, is at 99%.
• 20:48
  Professor Fred Watson: Yes. Yeah. Uh,
• 20:51
  so, yeah,
• 20:55
  it's kind of roughly something like that. I'm
• 20:57
  sure. I always used to use an example of
• 21:00
  um, going to a star a thousand light years.
• 21:04
  Sorry, a star 500 light years away. So you
• 21:06
  make a thousand year journey as elapsed
• 21:09
  on Earth and turns out that uh, I
• 21:12
  think it's 99.99995% of
• 21:15
  the speed of light. Uh, which is almost the
• 21:18
  speed of light. But the people on board have
• 21:20
  only aged 10 years. So you've got. In 10
• 21:23
  years you've gone a thousand years into the
• 21:25
  future on Earth.
• 21:27
  Andrew Dunkley: Um, it's crazy, isn't it?
• 21:28
  Professor Fred Watson: It's bizarre. Yeah, but, but the
• 21:31
  physics. So I, you know, as I
• 21:34
  said in last week's episode, I think to talk
• 21:36
  about interstellar travel, certainly for
• 21:39
  humans at the moment physics
• 21:42
  just says no way, Jose. It's.
• 21:44
  Andrew Dunkley: Yeah, my new book says otherwise.
• 21:47
  Professor Fred Watson: But of course it does. Yeah, but that's.
• 21:49
  You're in the real world of science fiction.
• 21:51
  Andrew Dunkley: Yes.
• 21:51
  Professor Fred Watson: Rather, rather than the artificial world of
• 21:54
  uh, relativity.
• 21:56
  Andrew Dunkley: Yeah. And just uh, to put Keith right in the
• 21:59
  picture, um, you know, if you want to get
• 22:02
  to light speed, we're a little bit behind at
• 22:04
  the moment. Uh, the Parker solar probe
• 22:07
  has currently uh, got the um, space
• 22:10
  speed record of
• 22:11
  0.064%
• 22:16
  of the speed of light. So we're nowhere
• 22:19
  near 1%. We're nowhere near
• 22:21
  0.1%.
• 22:24
  Professor Fred Watson: Is it 190 kilometres per second?
• 22:26
  Andrew Dunkley: I think it is, yes, yes, give or take.
• 22:29
  Um, that's as fast as we've ever been,
• 22:31
  um, as a species.
• 22:35
  But um, the day will come we'll get faster.
• 22:38
  If we could achieve 2%,
• 22:41
  um, that would make travelling to the outer
• 22:44
  solar system so much quicker.
• 22:45
  Professor Fred Watson: Yeah, it would, yes.
• 22:46
  Andrew Dunkley: It would take, it would drop the travel time
• 22:49
  to weeks.
• 22:50
  Professor Fred Watson: Yeah, yeah.
• 22:51
  Andrew Dunkley: Would be amazing. So, you know, we don't need
• 22:53
  the speed of light yet, but
• 22:56
  we do need to probably get a bit quicker. But
• 22:59
  uh, yeah, it's an impossible dream at the
• 23:02
  moment, Keith, I think would be the answer to
• 23:04
  your question. But um, we won't
• 23:07
  give up. I'm sure humanity will figure
• 23:09
  out a way to do it at some stage.
• 23:13
  Uh, but right now if we want to go anywhere,
• 23:15
  we've probably got to build a spaceship big
• 23:17
  enough for multiple generations to Live on.
• 23:20
  By the time they get there, they'll go, can
• 23:23
  anyone why we were coming here in the first
• 23:25
  place? Like, this place is the pits. Why did
• 23:28
  we come here?
• 23:30
  Professor Fred Watson: Exactly.
• 23:32
  Andrew Dunkley: Thank you, Keith. Great to hear from you.
• 23:36
  Professor Fred Watson: 0G and I feel fine.
• 23:38
  Andrew Dunkley: Space nuts now, final question comes from
• 23:41
  Mark. I love this question because of the
• 23:44
  first sentence. Am I the only person
• 23:47
  to have watched Space 1999 back in
• 23:50
  the 70s? No, you're not, Mark. I was a
• 23:52
  huge fan. I loved that show.
• 23:55
  Um, it, it was, uh, on.
• 23:59
  It was a British show, British, uh, science
• 24:01
  fiction TV programme that ran for two
• 24:03
  seasons, 75 to 77.
• 24:06
  Um, I watched it on Australian, uh,
• 24:09
  television and uh, it follows
• 24:11
  311 inhabitants of Moon Base
• 24:14
  Alpha, which is hurtling uncontrollably into
• 24:17
  space due to an explosion of nuclear waste
• 24:19
  stored on the moon's far side.
• 24:22
  And this is what's prompt Mark's question.
• 24:26
  Uh, I clearly remember a big nuclear
• 24:28
  explosion in that show. And next
• 24:31
  thing, the moon and the inhabitants of the
• 24:33
  moon of, uh, Moon Base Alpha are sent off on
• 24:36
  their merry way into deep space, leaving the
• 24:38
  Earth, uh, to wobble on its axis. On the
• 24:41
  bright side, I do like to sail, so
• 24:44
  I wouldn't have to worry about tides. So,
• 24:47
  you know, that's pretty cool.
• 24:49
  Um, what are your thoughts? P.S. i have
• 24:52
  cracked, uh, the screen on my phone, so this
• 24:54
  might not make much sense.
• 24:57
  Keep, uh, doing what you're doing. It brings
• 24:59
  me smiles. It brings a smile to my face. That
• 25:01
  comes from Mark. Um, so, yeah, all right,
• 25:04
  whatever reason, uh, but in this case it was
• 25:06
  nuclear waste explosion that sent the, uh,
• 25:09
  moon careening off into the heavens and
• 25:12
  left Earth all on its lonesome.
• 25:15
  Cause and effect. Um, what would be the
• 25:17
  effect, uh, as
• 25:20
  well, beyond the fact that the oceans would
• 25:22
  be much calmer and you could sail quite
• 25:25
  happily. Or would they? No,
• 25:27
  No, I didn't think so.
• 25:29
  Professor Fred Watson: No, I think it's the,
• 25:32
  um, it's the currents
• 25:35
  in the ocean and the atmosphere
• 25:38
  itself that really dictate what's
• 25:41
  happening to the surface of the ocean. The
• 25:44
  tidal phenomenon is just a really low
• 25:47
  frequency effect. Two high tides a
• 25:49
  day. Um, and yes, it does
• 25:52
  mean water's moving around.
• 25:55
  But, uh, the main,
• 25:58
  um, kind of source of motion in
• 26:01
  the oceans, I think, are these currents that
• 26:03
  we're concerned about because the atmosphere
• 26:06
  is changing. Uh, oceans are warming up
• 26:09
  and some of these currents are, uh,
• 26:12
  forecast to possibly switch off, like the one
• 26:15
  that's closest to my heart, because it's
• 26:17
  where I grew up. But, uh, the Gulf Stream
• 26:20
  Drift, which is a Current that comes up from
• 26:23
  the. Basically the West Indies, uh,
• 26:26
  and crosses the Atlantic and keeps Scotland
• 26:29
  warmer than it otherwise would be. Uh,
• 26:31
  um, and of course, western England as well,
• 26:34
  and Ireland too. But it's why you can
• 26:37
  find. When you look down the west coast of
• 26:39
  Britain, you can find palm trees, uh, growing
• 26:42
  in people's gardens because of that
• 26:44
  phenomenon.
• 26:44
  Andrew Dunkley: Floated over.
• 26:46
  Professor Fred Watson: Something like that. Yeah. Um,
• 26:49
  whereas without it, uh, we'd feel
• 26:52
  very much more severe winters. Or they would
• 26:54
  up there, because I'm now Australian, of
• 26:56
  course. Yeah. Oka. Um, so
• 27:00
  it's not going to do much to calm the ocean.
• 27:03
  Uh, it would get rid of the tides. Um, it
• 27:06
  might, as uh, Mark alluded
• 27:09
  to in his question, make the Earth wobble on
• 27:11
  its axis a bit more. But that would be over
• 27:14
  timescales of tens of thousands of years. Um,
• 27:17
  and we might be able to cope with that. But,
• 27:20
  um, of course we'd miss it because the moon
• 27:22
  is very romantic. And, um.
• 27:25
  Andrew Dunkley: Yeah, it's a good thing to photograph
• 27:27
  sometimes.
• 27:27
  Professor Fred Watson: It's great. That's right. It's good to have.
• 27:29
  Yeah.
• 27:30
  Andrew Dunkley: It wouldn't make life impossible for us if
• 27:33
  it.
• 27:34
  Professor Fred Watson: No, it wouldn't. Um, it would change life,
• 27:36
  definitely. But I mean,
• 27:39
  especially the accelerations that it would
• 27:41
  produce as it rocketed off into space
• 27:44
  might certainly upset things here on Earth.
• 27:47
  There'd be a gravitational influence on. That
• 27:49
  could change the length of the day.
• 27:51
  Andrew Dunkley: Yeah, that's a thought.
• 27:54
  Well, um, you know, people working harder and
• 27:57
  harder. You'd probably want the day to go
• 27:58
  longer,
• 28:02
  but I don't know. I don't know what would
• 28:04
  happen. It could be interesting, though.
• 28:07
  Professor Fred Watson: Well, it could, but, um, hopefully it's not
• 28:09
  going to happen.
• 28:11
  Andrew Dunkley: No. It is moving away from us though, Mark,
• 28:13
  and it will. Yeah, it will
• 28:17
  reach a certain distance and then that'll be
• 28:19
  it. It'll stop. It's not going to keep going
• 28:20
  away.
• 28:21
  Professor Fred Watson: That's correct.
• 28:21
  Andrew Dunkley: Yeah. But, um. But at the moment we're
• 28:24
  stuck with it. Um, that big grey rock that
• 28:27
  just sort of looms over us and looks
• 28:30
  pretty and, um, lights up the night.
• 28:33
  Professor Fred Watson: It's great.
• 28:33
  Andrew Dunkley: Yes. May soon have a colony on it. Ben's
• 28:36
  really thrilled about that.
• 28:39
  Professor Fred Watson: I don't mind a permanent presence, but, um,
• 28:42
  the idea of, you know, settling on the moon
• 28:44
  is, uh.
• 28:46
  Andrew Dunkley: That's Elon's goal now he's given up on Mars.
• 28:49
  Professor Fred Watson: Well, yeah, no, he's talking about Mars as
• 28:52
  well in the.
• 28:53
  Andrew Dunkley: Oh, I know. With the latest. That's the
• 28:55
  latest he's still got. Yeah. But I think
• 28:58
  he's decided we'll Go to the moon first and
• 29:00
  we'll see how we go there. Yeah, Bit worried
• 29:02
  about flushing toilets, but we'll figure that
• 29:03
  out.
• 29:07
  Uh, Mark, thank you. That's a great question.
• 29:09
  Lots of fun and, yeah, space 1999,
• 29:12
  probably one of the shows that really
• 29:14
  switched my brain onto science fiction and I
• 29:17
  haven't let go of it. Terrific show.
• 29:20
  Uh, that brings us to the end. But if you do
• 29:23
  have questions or comments for us, please
• 29:25
  visit our website because we'd love to hear
• 29:27
  from you. Uh, and if you've thought about
• 29:28
  sending in a question and just never got
• 29:30
  around to it, well, get around to it.
• 29:33
  SpaceNutsPodcast.com SpaceNuts
• 29:35
  IO are our URLs because
• 29:38
  we got a 2 for 1 package and you can just
• 29:40
  press the AMA button at the top, which means
• 29:43
  ask me anything and send us your audio or
• 29:45
  text questions. Don't forget to tell us who
• 29:47
  you are and where you're from. We always like
• 29:49
  to know. We've got people all over the place,
• 29:50
  but more listeners in Iceland than anywhere.
• 29:53
  We're number one in Iceland.
• 29:54
  Professor Fred Watson: Woohoo.
• 29:56
  Andrew Dunkley: It's very exciting. Um, but I think we're
• 29:59
  number two in Australia and number something.
• 30:02
  Number nine in America or something.
• 30:05
  Professor Fred Watson: Yes, Number five in the uk. I noticed number
• 30:08
  five in the uk.
• 30:09
  Andrew Dunkley: What happened to the other two people, I
• 30:10
  wonder? Anyway, um,
• 30:13
  Fred Watson, we've reached the end. Thank you
• 30:15
  so much.
• 30:16
  Professor Fred Watson: Great pleasure, Andrew. Always good fun.
• 30:19
  Andrew Dunkley: And, uh, thanks to Huw in the studio, who
• 30:21
  couldn't be with us today, which is why we're
• 30:23
  number two in Australia instead of number
• 30:25
  one. He just never listens. And from me,
• 30:28
  Andrew Dunkley, thanks for your company.
• 30:30
  We'll see you on the next episode of Space
• 30:31
  Nuts. Bye Bye.
• 30:34
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• 30:36
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• 30:51
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