Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / Q&A: Cosmic Mapping, Light Speed Anomalies & The Nature of Time

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Q&A: Cosmic Mapping, Light Speed Anomalies & The Nature of Time · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Heidi Campo: Welcome back to another fun and exciting Q
• 0:02
  and A episode of space duts.
• 0:05
  Andrew Dunkley: 15 seconds.
• 0:06
  Professor Fred Watson: Guidance is internal. 10,
• 0:08
  9. Ignition sequence start.
• 0:12
  Space nuts. 5, 4, 3, 2. 1.
• 0:14
  Andrew Dunkley: 2, 3, 4, 5, 5, 4, 3, 2,
• 0:17
  1. Space nuts.
• 0:19
  Professor Fred Watson: Astronauts report it feels good.
• 0:21
  Heidi Campo: I'm your host for this episode, Heidi Campo.
• 0:23
  And joining us today is our beloved
• 0:26
  professor Fred Watson,
• 0:29
  astronomer at large. How are you doing today,
• 0:31
  Fred?
• 0:32
  Professor Fred Watson: Very well, thank you, Heidi. And, um, you
• 0:35
  look, uh, as though you're in fit and well
• 0:37
  compared with the way you've been the last
• 0:39
  week or two. I hope you're feeling better,
• 0:42
  but all good here at this end.
• 0:44
  Heidi Campo: Yeah, slowly but surely. I
• 0:47
  got a little bit of. A little upper
• 0:49
  respiratory, just a cough, a little bit of a
• 0:52
  fever, but that's. I always just say,
• 0:54
  um, I know this isn't like a health and
• 0:56
  fitness podcast, but it's so important to
• 0:58
  take care of your body. Eat your vitamins.
• 1:01
  Um, if you're from my generation, you can
• 1:03
  say, eat your Wheaties. I don't
• 1:06
  know. They still make those, don't they?
• 1:08
  Professor Fred Watson: Um, I don't know.
• 1:11
  I'm not sure what we're talking about.
• 1:13
  Heidi Campo: The Wheaties. The Wheaties cereal, it was
• 1:15
  the, uh, it was a. Ah, it was the breakfast
• 1:18
  of champions. And they would always put a big
• 1:20
  sports superstar on the Wheaties cereal box.
• 1:23
  Professor Fred Watson: Okay.
• 1:24
  Heidi Campo: And so in the 90s and the early 2000s, people
• 1:26
  would always say, eat Wheaties. Yeah, of
• 1:28
  course, is the thing of saying, like, you
• 1:31
  know, that's what. What you do to be
• 1:32
  healthier. My house growing up, we'd watch a
• 1:35
  lot of Popeye. And my grandpa. My grandpa
• 1:37
  would always read me Popeye, so he would be
• 1:39
  like, make sure you're eating your spinach.
• 1:41
  Professor Fred Watson: Yes, of course. That's the. Certainly
• 1:44
  the secret that Popeye had.
• 1:47
  Heidi Campo: Yeah. Eat your Wheaties, eat your spinach,
• 1:49
  take your vitamins. Whatever you gotta do to
• 1:52
  keep yourself healthy.
• 1:53
  All right, well, let's just jump right into
• 1:56
  our questions, um, from our listeners.
• 1:59
  So in these Q and A episodes, if you are new
• 2:02
  here, we do do an episode where Fred
• 2:04
  tells us all about everything exciting
• 2:07
  happening in space. And then we follow it up
• 2:09
  with a Q A episode where you, the
• 2:12
  listener, ask us your questions and Fred
• 2:15
  answers them. And sometimes I'll chime in,
• 2:17
  and when Andrew's back, he'll be chiming in
• 2:20
  with his wonderful dad jokes. I have not been
• 2:22
  doing good with the dad jokes. I'm sorry.
• 2:25
  Professor Fred Watson: It's a relief, actually. It's great not to
• 2:27
  have the dad jokes.
• 2:30
  Heidi Campo: All right, well, our first question today is
• 2:33
  a Written question and it's a bit longer.
• 2:36
  And this question is from Sam
• 2:39
  and Sam says thank you for your
• 2:42
  podcasts. Thank you for inviting listener
• 2:44
  questions and for your helpful answers. It
• 2:46
  supports making learning a lifelong
• 2:49
  adventure. There's been a lot of discussion
• 2:52
  about increasing opportunities to 3D map
• 2:55
  the universe. With our various new telescopes
• 2:58
  coming, uh, online, I am
• 3:00
  struggling with trying to understand,
• 3:02
  visualize what is being attempted to be
• 3:05
  portrayed in the variety of efforts at
• 3:08
  3D mapping of the universe or large
• 3:10
  subsets thereof.
• 3:13
  Although the idea of 3D portrayal seems
• 3:15
  obvious, especially when dealing with
• 3:17
  something fairly local or close by,
• 3:20
  it seems to me it would be problematic when
• 3:23
  we are using the light we receive today,
• 3:26
  but was, uh, emitted millions or billions of
• 3:29
  years ago. Do the 3D map show the locations
• 3:31
  of the galaxies and other structures in the
• 3:34
  positions they were at when the light we
• 3:37
  are now using was actually emitted? Or
• 3:40
  are the galaxy locations manipulated to fast
• 3:43
  forward them where they would be estimated to
• 3:46
  be currently? It seems to me that either view
• 3:49
  would have its problems in portraying a 3D
• 3:52
  picture attempting to show relative positions
• 3:54
  and locations. But relative to what in space
• 3:57
  and. Or time? Ooh, this is a really
• 4:00
  interesting question.
• 4:02
  Professor Fred Watson: It is, it's a great question. Uh, Sam? Um,
• 4:05
  and um, the
• 4:07
  answer is that when we,
• 4:10
  when, you know, particularly when we're
• 4:12
  looking at great distances,
• 4:15
  uh, at galaxies that are millions of billions
• 4:17
  of years ago, uh, light years away,
• 4:20
  we think in terms of look back times.
• 4:23
  So we're looking back in time
• 4:26
  because that's the only thing we can measure.
• 4:29
  We measure something called the redshift,
• 4:31
  which is a number that relates to,
• 4:34
  ah, how basically it
• 4:37
  relates to size of the universe when the
• 4:39
  light was emitted. Uh, so we measure the
• 4:41
  redshift and that tells us how far back in
• 4:44
  time we're looking for, uh,
• 4:48
  our depictions of these objects. And that's
• 4:51
  all we have. Um, it's
• 4:53
  nearly all we have. There is one other thing
• 4:55
  I'll tell you about in a minute. But um, the
• 4:58
  bottom line is that when we build these maps,
• 5:01
  basically we're putting in look back times
• 5:03
  rather than distances. We think of them as
• 5:05
  distances, but they're look back times. And
• 5:08
  so yes, we are depicting where that
• 5:11
  galaxy was, uh, when the light received,
• 5:14
  uh, when the light left it, basically.
• 5:17
  So it's the galaxy
• 5:20
  positions, ah, not manipulated
• 5:22
  in any way. It's directly read from the
• 5:25
  look back time. The one caveat to that that
• 5:28
  I've mentioned is that um, galaxies
• 5:32
  as well as the flow of
• 5:35
  uh, what we call the Hubble flow, the fact
• 5:38
  that the universe Is expanding.
• 5:41
  Heidi Campo: I hear a little rooster in the background.
• 5:44
  Professor Fred Watson: Yeah, he's just seen somebody he knows.
• 5:47
  That's our dog, believe it or not. Not the
• 5:49
  rooster.
• 5:51
  Um, um, forgive me if
• 5:53
  I just go and check that it's what I think it
• 5:55
  is. Sorry, I'll be back in a second. We can
• 5:58
  cut this out. Uh, okay.
• 6:00
  Um, so the. Let me pick up where I
• 6:03
  was talking about. The caveat, uh,
• 6:06
  the thing that distinguishes, um,
• 6:10
  the position of a galaxy from where we
• 6:13
  think of it in terms of its look back time,
• 6:15
  uh, is that we can for some galaxies,
• 6:18
  particularly relatively nearby ones out to
• 6:20
  perhaps just, you know, a billion light years
• 6:22
  or so, maybe a little bit longer than that, a
• 6:25
  bit further than that. Uh, we can also
• 6:27
  measure something called the peculiar motion
• 6:30
  of the galaxies. The peculiar velocity. And
• 6:33
  what this is, is the velocity
• 6:36
  a galaxy has that, uh,
• 6:38
  is a result of local
• 6:42
  gravitational forces. So if you've got a big
• 6:44
  cluster of galaxies, they'll be moving around
• 6:47
  a sort of center of mass. They'll have what
• 6:50
  we call a peculiar motion which is distinct
• 6:53
  from their motion because of the
• 6:55
  expansion of the universe. I'm not sure
• 6:57
  whether I'm making this clear. Um, but the
• 7:00
  way we describe it usually is if you think of
• 7:02
  a river flowing, uh, and you
• 7:05
  imagine boats on that river, they
• 7:08
  have their own motion, uh, across the
• 7:11
  water, but they're also being carried along
• 7:13
  by the motion of the river itself. And that's
• 7:16
  an analog with what's happening with the
• 7:18
  galaxies. They've got their own individual
• 7:20
  motions as well as what we call the Hubble
• 7:22
  flow. The fact that they're moving because of
• 7:24
  the expansion of, of the universe. And
• 7:27
  you could in principle take
• 7:30
  those peculiar velocities and
• 7:32
  say, well, um, you know,
• 7:35
  if you think about where they are now, those
• 7:38
  galaxies, their positions will have changed.
• 7:41
  But in terms of the change
• 7:44
  compared with the distance that we're looking
• 7:46
  at, the changes are negligible over the
• 7:49
  timescales that we are talking about. Even
• 7:51
  though it's billions of years. Um, uh, when,
• 7:54
  when you're talking about things billions of
• 7:55
  light years away, uh, and you're talking
• 7:58
  about, you know, maybe a few,
• 8:00
  um, it's more than millions of
• 8:03
  kilometers, but it's, it's, it's so small
• 8:06
  compared with the size of the universe that
• 8:08
  you would never know the difference. So
• 8:11
  basically we just take what we get from our
• 8:13
  measurement of distance and plot the maps
• 8:15
  that way. A long answer to a fairly long
• 8:18
  question, Sam. I hope that explains why
• 8:20
  what's going on there.
• 8:22
  Heidi Campo: Well, that was, that was a really Fun
• 8:23
  question. Um, thank you for answering it.
• 8:29
  Professor Fred Watson: Roger. Your lot right here also.
• 8:31
  Heidi Campo: Space Nuts, our next question
• 8:34
  is from Mark, and this is going to
• 8:37
  be a audio question. Uh,
• 8:39
  Mark, Mark from Quebec. So we're going
• 8:42
  to, uh, cue that up and play that for you
• 8:45
  guys right now. So Fred and I are going to
• 8:47
  get that ready, we'll listen to it, and we'll
• 8:49
  play it for you as well. We're going to play
• 8:51
  that question you right now.
• 8:54
  Andrew Dunkley: Hello, Space Nuts. My name is Mark. I'm
• 8:56
  recording from Sherbrooke in the beautiful
• 8:58
  province of Quebec. Now, I have a
• 9:01
  question about the speed of light. So
• 9:04
  when we talk about the speed of light, we
• 9:06
  assume it's the speed of light in the vacuum
• 9:09
  of space, right? I've heard that,
• 9:12
  uh, the speed of light can slow down by
• 9:14
  something around like 40%
• 9:18
  when, uh, it's traveling through matter like
• 9:21
  water or diamonds. Now, if an
• 9:23
  astronaut in space would shine a
• 9:26
  laser beam through a diamond.
• 9:28
  Professor Fred Watson: Held.
• 9:31
  Andrew Dunkley: At the top of his fingertips,
• 9:34
  let's say the light would travel through the
• 9:36
  diamond at a reduced speed, right?
• 9:39
  But once the light exits the diamond
• 9:42
  and is back in the vacuum of space, would
• 9:45
  it continue traveling at a reduced speed or
• 9:47
  would it resume its initial speed?
• 9:50
  And if it did resume its initial
• 9:53
  speed, where would it get the energy
• 9:56
  to accelerate again? Now, I know that the
• 9:59
  light has no mass, but I
• 10:02
  kind of can't imagine how light could travel
• 10:05
  at the reduced speed or how it
• 10:08
  could automatically, uh, return to its
• 10:10
  original speed after being slowed down.
• 10:13
  So I would really like if you could help me
• 10:16
  understand this, uh, how
• 10:19
  this works. So thank you very much. Great,
• 10:22
  great show. Thank you for all, uh, your
• 10:24
  work, guys.
• 10:25
  Andrew Dunkley: Bye bye.
• 10:26
  Professor Fred Watson: That's a great, great question. Um,
• 10:29
  and it's a little bit
• 10:32
  like, it's kind of related to a question that
• 10:34
  we, we've had some time ago, um,
• 10:37
  which is about, um,
• 10:41
  when photons are emitted,
• 10:43
  uh, how long does it take them to accelerate
• 10:46
  to the speed of light? Um, and the
• 10:49
  answer is they're emitted at the
• 10:52
  speed of light. And so, um,
• 10:55
  this question, uh, I think I
• 10:58
  would tackle it in the same way as I tackled
• 11:00
  that other question. And that is that light
• 11:03
  is not just a stream of particles, uh,
• 11:06
  which, as, uh, Mark says, are massless.
• 11:09
  Effectively, they've got no rest mass, um,
• 11:11
  but it's also a wave motion. And
• 11:14
  that's perhaps the easier way to understand
• 11:16
  what's going on here. Uh, you've got
• 11:19
  these waves, um, which
• 11:21
  encounter a surface, perhaps a diamond
• 11:24
  or a water surface, and indeed they do slow
• 11:27
  down, uh, the propagation of the wave slows
• 11:30
  down. Uh, but then when
• 11:33
  they leave that surface, when they leave that
• 11:35
  material on the other side, they go back to
• 11:38
  the same speed. And that's
• 11:41
  much easier to understand from the point
• 11:44
  of view of wave motion than it is from the
• 11:46
  idea of streams of particles. Uh, because the
• 11:49
  same thing happens, uh, um, in water
• 11:52
  waves. If you have water waves that are
• 11:54
  propagating on a surface and they come to
• 11:57
  a shallow region, their velocity will change.
• 11:59
  And then if they come to a deeper region,
• 12:01
  they go back to where they were before. Um,
• 12:04
  so the speed of light in a vacuum is one of
• 12:06
  these strange things. It's immutable. It does
• 12:09
  not change. It's always 300,000 kilometers
• 12:11
  per second. I think we discussed this in the
• 12:13
  last Q and A session. Uh, we talked at length
• 12:16
  about it. So, um, quite
• 12:18
  counterintuitive. And I can understand
• 12:21
  why your question arises, Mark. But think of
• 12:24
  it as waves, and it's much easier to
• 12:26
  understand what's going on.
• 12:27
  Heidi Campo: Excellent, Fred. Thank you.
• 12:29
  Um, our next question is from Rennie
• 12:32
  Traub from Sunny Hills, California.
• 12:35
  And Rennie has a short and sweet question.
• 12:38
  And it is, how great is the
• 12:40
  heliosphere around our solar system?
• 12:43
  And do all or most solar systems
• 12:45
  have one?
• 12:48
  Professor Fred Watson: Um, yeah. Great questions,
• 12:50
  Rennie, one of our regular questioners. There
• 12:53
  are always good questions from Rennie. This
• 12:54
  is a good one too. Um, uh,
• 12:57
  so it's only an estimate,
• 13:00
  uh, although we do have some measurements
• 13:03
  that lead us to believe this estimate is
• 13:06
  somewhere near the truth. Because we've got,
• 13:09
  uh, five spacecraft which are leaving the
• 13:11
  solar system. Uh, and they are, I
• 13:14
  think, all equipped with magnetometers. The
• 13:16
  two pioneers, the Voyagers and New, uh,
• 13:19
  Horizons, I think they've all got
• 13:20
  magnetometers on board. And the heliosphere
• 13:23
  is the Sun's, uh, sphere of
• 13:25
  magnetic influence. Uh, and so those magnetic
• 13:29
  magnetometers can basically give you.
• 13:32
  Give, uh, you an idea of what,
• 13:34
  uh, what, you know, what the dimensions of
• 13:37
  the heliosphere are. And it's in the
• 13:40
  region of.
• 13:44
  It's basically
• 13:47
  measured in astronomical units. An
• 13:49
  astronomical unit is the distance between the
• 13:51
  Earth and the sun. Something in the region
• 13:54
  of 100 astronomical units,
• 13:59
  uh, is the radius. Um, and
• 14:02
  so, uh, it's
• 14:05
  not spherical. It's got a
• 14:07
  peculiar shape, which is probably because
• 14:10
  of the sun's motion through
• 14:13
  the galaxy's magnetic field. That distorts
• 14:16
  the shape of the heliosphere. Uh, but, um,
• 14:19
  it's roughly, as I said, a radius
• 14:22
  of, uh, about 100 astronomical units. So
• 14:25
  what is that? It's 100 times 150. 50 million
• 14:28
  kilometers, uh, which
• 14:30
  is um, if my
• 14:33
  mathematics is right it's about 15 billion.
• 14:35
  Is that right? Thereabouts, yeah. 15 billion
• 14:38
  kilometers. Something of that size. So it's,
• 14:41
  it's and the voyagers uh,
• 14:43
  are both uh, further than that
• 14:46
  distance and so they have ah,
• 14:49
  sensed the edge of the magnetosphere. Uh,
• 14:52
  um, we keep seeing headlines.
• 14:55
  Um, they're leaving the solar system. Well
• 14:57
  that's not really quite the case because the
• 15:00
  solar system encompasses the Oort cloud which
• 15:02
  is a lot further out. But they are probably
• 15:04
  leaving the heliosphere, the region of the
• 15:07
  Sun's magnetic influence. And uh, to
• 15:10
  answer your question Renny, fully, uh,
• 15:13
  yes, uh, sun like stars, like ours would
• 15:15
  have a heliosphere. Some stars are far more
• 15:18
  magnetic, uh, uh, than the sun is
• 15:21
  and so they would probably have a bigger
• 15:23
  heliosphere depending on the type of star it
• 15:25
  is. Uh, but yet they'll be common to all
• 15:27
  stars we think because magnetism plays such a
• 15:29
  huge role in the way stars work.
• 15:32
  Heidi Campo: Another good high impact question from
• 15:34
  Rennie.
• 15:37
  Andrew Dunkley: 0G and I feel fine Space nuts.
• 15:40
  Heidi Campo: Um, our very last question today is
• 15:43
  another audio question and this one is from
• 15:45
  Dean in Queensland. And
• 15:48
  we are going to go ahead and play the audio
• 15:50
  question for you all now.
• 15:52
  Andrew Dunkley: Hi Fred, Heidi and Andrea. My question is
• 15:55
  about time dilation, but I've had to break it
• 15:57
  into three parts. I hope that's okay. First
• 16:00
  part concerns um, the Kelly twins, whose ages
• 16:03
  diverge slightly because of time dilation
• 16:05
  when one of them spent a year on the ISS
• 16:07
  orbiting the Earth. I've read that a person
• 16:10
  moving at high speed experiences times slower
• 16:12
  than a slow moving person. However, speed is
• 16:15
  relative. If two people in space were moving
• 16:18
  away from each other at a constant rate, then
• 16:20
  each one would perceive the other to be the
• 16:23
  one doing the moving. In that case, what
• 16:25
  determines which one would have the slower
• 16:28
  time? This question makes me wonder whether
• 16:31
  it's acceleration that causes the time
• 16:33
  dilation rather than just speed. This could
• 16:36
  explain the Kelly twin's age difference as
• 16:38
  the the ISS orbital motion is a form of
• 16:41
  acceleration. Plus there was also a linear
• 16:44
  acceleration to get into orbit in the first
• 16:46
  place. Part two is about the
• 16:49
  idea that an object in a high gravity field
• 16:51
  experiences time slower than an object in low
• 16:54
  gravity. If this is correct, is
• 16:57
  it independent from speed induced time
• 16:59
  dilation? And could these two effects add
• 17:02
  together if an object is
• 17:05
  moving very fast and it's within a uh, high
• 17:07
  gravity field? Part three is
• 17:10
  about uh, descriptions of time
• 17:12
  spans in the early uh, universe. Certain
• 17:15
  events Are, uh, described as happening within
• 17:18
  a specific number of years of the Big Bang.
• 17:21
  However, if time runs slower in a high
• 17:24
  gravity field, then it must have generally
• 17:26
  run slower when all the baryonic matter
• 17:29
  in the early universe was densely packed in a
• 17:32
  smaller space time. And if that is true,
• 17:35
  then the period of 100,000 years from the Big
• 17:38
  Bang would not be equivalent to a period
• 17:42
  of 100,000 years here on Earth. Is that
• 17:45
  correct? I probably have a lot of this
• 17:47
  wrong. Can you explain it for me? Thanks
• 17:50
  again for the podcast.
• 17:52
  Professor Fred Watson: Um, Dean, you don't have a lot of it wrong. I
• 17:55
  think you've got a lot of it right. Um,
• 17:58
  so, um, the first and second parts
• 18:01
  of your question, I think really merge into
• 18:03
  one. Uh, because I think the difference in
• 18:05
  ages with the Kelly twins, I think it was the
• 18:08
  gravitational time dilation that was being
• 18:11
  taken into account rather than the velocity
• 18:13
  time dilation. I'm not sure about that.
• 18:16
  Uh, but both of those effect. You're quite
• 18:18
  right that accelerations also play a role in
• 18:21
  this too. Um, certainly for the
• 18:24
  velocity time dilation, it's what allows
• 18:27
  the twins paradox to work. Uh, because you've
• 18:29
  got accelerations at, uh, the beginning and
• 18:31
  end of the twin one twins voyage to
• 18:34
  the nearest star and back again.
• 18:37
  Um, but yes, the gravitational and,
• 18:40
  um, velocity time dilations, they're both
• 18:43
  caused by relativity. The two different
• 18:46
  relativity theories. Special, uh, relativity
• 18:49
  in 1905 talked about velocities.
• 18:52
  When you get velocities going near the speed
• 18:54
  of light, all kinds of weird things happen,
• 18:56
  including the phenomenon of time dilation. A
• 18:59
  stationary observer will see somebody else's
• 19:01
  clock moving slower, ah, as they whiz by
• 19:04
  at nearly the speed of light. And then in,
• 19:07
  um, 1915, uh, the
• 19:10
  general theory of relativity, which was about
• 19:12
  the way gravitation works. And it turns out
• 19:15
  that gravity does the same thing. Uh,
• 19:17
  gravitational time dilation. If you're in
• 19:20
  a gravitational field, your clocks are
• 19:22
  running slower than if you're outside it. Um,
• 19:24
  and the closer you are, for example,
• 19:27
  to the Earth, the slower your clocks will run
• 19:29
  compared with somebody who is in orbit. I
• 19:31
  think that was the issue with the Kelly twin
• 19:33
  winds. Um, it's
• 19:35
  microseconds. It's tiny, tiny amount of time.
• 19:38
  Uh, when you consider the distance between
• 19:40
  the Earth's surface and the height of the
• 19:42
  International space station at 400
• 19:43
  kilometers, uh, it's a very small difference,
• 19:46
  but it is measurable. Um, in fact, I think it
• 19:49
  is even measurable, uh, with aircraft. If you
• 19:51
  fly an atomic clock on board an aircraft, I
• 19:54
  think from a Ground based observer, it looks
• 19:56
  as though, um, it's going faster than what
• 19:59
  we measure time here on Earth. Uh,
• 20:02
  so, um, that's basically sorting
• 20:04
  out those issues. Uh, your third part of
• 20:07
  the question. It's certainly true that when
• 20:10
  we look back at phenomena that are
• 20:12
  sort of time tagged, if I can put it that
• 20:15
  way, in the early universe, we do see time
• 20:17
  dilation. Um, and, uh,
• 20:21
  I'm thinking particularly of
• 20:23
  supernova explosions where a star
• 20:26
  explodes, its brilliance goes up and
• 20:28
  then decays slowly afterwards. Uh,
• 20:31
  it turns out that you see the decay time
• 20:34
  changing from our perspective, uh,
• 20:38
  on the gravitational, you know, on
• 20:42
  um, Earth, uh, 13.8 or however many
• 20:45
  billion years later when we observe
• 20:48
  these phenomena. So, um, the same
• 20:51
  would be true of, uh, the early universe. And
• 20:54
  I think that's taken into account with
• 20:56
  people's calculations about this. I think
• 20:58
  time dilation falls directly within the
• 21:01
  province of cosmologists who understand it
• 21:03
  obviously a lot better than, than I do. Um,
• 21:05
  but, yeah, that's the bottom line.
• 21:07
  Heidi Campo: Yeah. And the time dilation is always, uh,
• 21:10
  it's always so hard to wrap your head around,
• 21:12
  but you do a great job of explaining it to
• 21:14
  us.
• 21:16
  Professor Fred Watson: Um, I just try and put it into terms that
• 21:19
  I can understand myself, which is not always
• 21:21
  the cleverest way to do it, but that's all
• 21:23
  right.
• 21:25
  Heidi Campo: Well, that, that wraps up all of
• 21:28
  our questions for today. Um, Fred,
• 21:31
  thank you so much for always being available
• 21:34
  to help us out with all of our questions. And
• 21:36
  to you, the listeners, please keep sending in
• 21:39
  your awesome, well thought out questions. You
• 21:41
  guys are really so smart. Every time I read
• 21:43
  your questions, I'm like, how are you guys
• 21:45
  even thinking of this stuff? Uh, you guys are
• 21:47
  brilliant. So keep sending in your
• 21:50
  questions. Um, you only have, like I said,
• 21:52
  you only have a few more weeks with me before
• 21:54
  Andrew is back, and so take advantage
• 21:57
  of that.
• 21:58
  And I guess without further ado,
• 22:01
  Fred, do you want to sign us off? Do you have
• 22:03
  anything else you want to say?
• 22:05
  Professor Fred Watson: No, just keep the questions coming exactly as
• 22:07
  you've said, Heidi. And, uh, thanks again to
• 22:09
  all of our great listeners who sent in
• 22:12
  questions. Thanks to you, Heidi, for keeping
• 22:14
  the show going and we'll, uh, see you next
• 22:17
  time. You'll be listening to the
• 22:20
  SpaceNuts podcast.
• 22:23
  Andrew Dunkley: Available at Apple Podcasts, Spotify,
• 22:25
  iHeartRadio, or your favorite podcast
• 22:28
  player.
• 22:29
  Professor Fred Watson: You can also stream on demand at Bytes.
• 22:31
  Com. This has been another quality podcast
• 22:34
  production from Bytes. Com.
• 22:36
  Heidi Campo: Um.