Latest / Space News Today / Cosmic Q&A: Black Holes, Stellar Densities & the Sun’s Sudden Disappearance | Space Nuts:...

Transcript

Cosmic Q&A: Black Holes, Stellar Densities & the Sun’s Sudden Disappearance | Space Nuts:... · Space News Today

• 0:00
  Hi there. Thanks for joining us on a Q&A
• 0:02
  edition of Space Nuts, our first one for
• 0:04
  the year. My name is Andrew Dunley, your
• 0:07
  host. And we've got questions from
• 0:09
  Justin, who's um got a sent us an audio
• 0:12
  question. Um he he's talking about the
• 0:15
  space that contains the equivalent to 4
• 0:18
  million stars in comparison to a black
• 0:20
  hole, I think. Can't remember. I I don't
• 0:23
  write down enough when I write down the
• 0:24
  descriptions of questions. Uh Charles,
• 0:28
  >> you're right.
• 0:29
  >> Fred's Fred's saying the same thing. Uh
• 0:32
  Charles says um is asking us a question
• 0:35
  about the retraction of uh the universe,
• 0:38
  the shrinking of it. Uh and Dean is
• 0:41
  asking about what might happen if the
• 0:44
  sun instantaneously disappeared. What
• 0:46
  would be the effect on our solar system
• 0:49
  and our planet specifically? And Patrick
• 0:52
  has some thoughts about uh both the
• 0:54
  Voyagers one and two. Mainly the fact
• 0:57
  that the data we've put on the plaques
• 0:59
  that have been put on board the Voyagers
• 1:02
  is actually telling anyone who finds
• 1:04
  them a lie. That's all coming up in this
• 1:07
  edition of Space Muts. And with us once
• 1:10
  again to decipher all of that gibberish
• 1:13
  that I just mentioned, and it's not the
• 1:16
  questions that are gibberish, it's my
• 1:17
  interpretation of them, is Professor
• 1:19
  Fred Watson, astronomer at large. Hello,
• 1:21
  Fred.
• 1:22
  >> Hi, Andrew. Your interpretation was more
• 1:25
  or less the same as what I thought when
• 1:26
  I saw them. So, I think we're on the
• 1:29
  same wavelength, which is good.
• 1:30
  >> Okay. Okay. Well, that's good. Uh, we
• 1:33
  might as well just hit them straight on
• 1:35
  the head. And our first question is an
• 1:37
  audio question and this one comes from
• 1:39
  Justin.
• 1:40
  >> Good day Andrew and Fred. I'm Justin
• 1:42
  down in Melbourne. Like Fred, I'm an
• 1:45
  expat pong and my astronomical claim to
• 1:48
  fame is that I witnessed the total solar
• 1:51
  eclipse in Cornwall in the UK in 1999.
• 1:55
  Two friends and I camped nearby and
• 1:57
  joined the crowds at New Key Beach on
• 2:00
  that day for a lifetime bucket list
• 2:02
  event.
• 2:04
  So, I have a mathematical question. I've
• 2:07
  often heard it said that the black hole
• 2:08
  at the center of the Milky Way galaxy,
• 2:10
  Sagittarius A star, is 4 million solar
• 2:14
  masses. So, for comparison, what would
• 2:18
  the radius be in light years of a sphere
• 2:21
  centered on the Earth that contains the
• 2:23
  nearest 4 million stars?
• 2:26
  Thanks very much.
• 2:28
  >> Thank you, Justin Cornwall. That's where
• 2:30
  my family originated
• 2:33
  before they um they got sent out here.
• 2:36
  No, I think they came voluntarily.
• 2:38
  We we didn't come with the convicts. We
• 2:40
  we came out later. But um yeah, Justin,
• 2:43
  good question. 4 million stars. Um what
• 2:46
  sort of space would that take up in
• 2:48
  terms of a radius in light years, I
• 2:50
  think, was the the guts of his question.
• 2:52
  >> Yeah. So, it's a a little bit more
• 2:55
  subtle than that. It's saying I figured
• 2:57
  it might be
• 2:58
  >> if you if you're sitting here on planet
• 3:00
  Earth um what sort of you know in our
• 3:05
  locality uh in the um western spiral arm
• 3:11
  the galaxy it's the Orion spur where we
• 3:13
  are uh that spiral arm that we sit in um
• 3:17
  what's the it's so it's really a
• 3:19
  question about the density of stars in
• 3:21
  our region uh and that's something very
• 3:24
  well established because we know the
• 3:25
  distances of lots of stars. Uh so I'm
• 3:29
  I'm going to put it in much rounder
• 3:32
  figures. Uh but um if you look at uh out
• 3:39
  to a thousand light years, okay, so you
• 3:42
  got a a sphere of radius a thousand
• 3:44
  light years, then that's going to have
• 3:47
  something like 10 million stars in it.
• 3:50
  >> Wow. So that's more than what uh what um
• 3:54
  Justin's talking about. Uh but the way
• 3:57
  this changes uh it changes nonlinearly.
• 4:00
  Uh so I'm guessing so I'm going to take
• 4:03
  a guess that you know around 9 900 light
• 4:06
  years or thereabouts you would probably
• 4:10
  have something like 4 million stars
• 4:12
  which is the same
• 4:15
  mass as the mass of the uh super massive
• 4:18
  black hole at the center of the galaxy.
• 4:20
  So, it's actually quite a long way. You
• 4:22
  know, you're looking at um yeah, several
• 4:24
  hundred light years uh uh in in terms of
• 4:27
  radius.
• 4:29
  Uh and um it's actually I think you
• 4:32
  would probably be able to find a tool
• 4:34
  online. I haven't found it myself
• 4:36
  because I haven't really looked for it,
• 4:37
  but I bet you can find a tool that gives
• 4:39
  you the exact answer to that. Uh how
• 4:42
  many stars are within a radius of x
• 4:44
  number of light years? And if you put in
• 4:47
  a good guess of light years, you'll
• 4:49
  probably get the right number of of
• 4:51
  stars.
• 4:51
  >> Do you want me to test it?
• 4:53
  >> Yeah, if you can find one.
• 4:54
  >> Yeah, I've got an idea. So, what's the
• 4:56
  question? How many stars in uh say
• 5:02
  within 900 light years?
• 5:04
  >> Okay. See what it is. This is a life
• 5:08
  >> uh radius
• 5:09
  of 900 light years.
• 5:13
  Okay.
• 5:15
  Let's see what happens here. Um, I'll
• 5:18
  just make sure I ask the question
• 5:19
  correctly.
• 5:22
  And nothing. Oh, here we go. Uh,
• 5:26
  uh, it's saying
• 5:28
  10 to 15 million.
• 5:31
  >> Yeah. Um, which is different from the
• 5:33
  calculation I saw, which is 10 million
• 5:36
  in a thousand. So, drop it down a bit.
• 5:38
  Can you put it down to 500 light years?
• 5:40
  See what it says for that.
• 5:41
  >> Okay. This is AI I assume that
• 5:44
  >> is doing all this for you on
• 5:46
  >> Mr. I absolutely love it.
• 5:49
  >> Um two to two and a half million stars.
• 5:53
  >> Yeah. So it's it's somewhere between 500
• 5:56
  and a thousand light years.
• 5:57
  >> There you go.
• 5:57
  >> So you put in whatever number you like
• 5:59
  and it'll give you the right answer. And
• 6:01
  Justin can have a lot of fun doing that.
• 6:03
  It's a great question actually.
• 6:04
  >> It's working out the averages. So
• 6:07
  750 light years transposes to 7 to 8
• 6:11
  million stars. So
• 6:12
  >> yeah.
• 6:13
  >> Yeah.
• 6:15
  >> There you go. You could do this all day
• 6:17
  really.
• 6:20
  >> Um I don't think we've ever been asked
• 6:21
  that before.
• 6:22
  >> No, I don't think so either.
• 6:23
  >> Not in that that way. Um
• 6:26
  >> we have had questions about you know the
• 6:27
  density the average density of stars in
• 6:29
  the solar neighborhood and that's really
• 6:31
  what this is all about.
• 6:32
  >> Yeah.
• 6:32
  >> Uh but uh yeah good stuff Justin. Thank
• 6:35
  you for your question and greetings to
• 6:37
  me Melbourne. It's 42 in Melbourne
• 6:38
  today, I think.
• 6:39
  >> Yes. Um we've we've got 38 here today. I
• 6:42
  went and played golf in that this
• 6:44
  morning and uh I was what's the word I
• 6:46
  used one of my friends used to use a lot
• 6:49
  when he was tired. I was jigged by the
• 6:51
  end of it.
• 6:52
  >> Jiggered. That's
• 6:52
  >> jigged. I don't know where it comes
• 6:53
  from.
• 6:53
  >> Granddad used to use that.
• 6:55
  >> Yeah.
• 6:56
  >> Yeah. Ah, wheel it in. It's jigged.
• 6:59
  >> Yeah. It was uh it was a tough day out,
• 7:01
  I must say. Uh thanks, Justin. Our next
• 7:03
  question comes from Charles. Uh, but
• 7:06
  because I've been using chat GPT to
• 7:09
  solve all the pro riddles of the
• 7:10
  universe, I've lost the question. All
• 7:12
  right. If
• 7:13
  >> if the universe does cease expanding and
• 7:17
  retracts, does that mean the lifetime of
• 7:20
  the universe goes from untold trillion
• 7:24
  beyond trillions of years or just a
• 7:26
  measly few billion? This one comes from
• 7:29
  Charles in Brooklyn and New York. I was
• 7:31
  in Brooklyn. Not so long ago. Walked
• 7:34
  across the Brooklyn Bridge.
• 7:36
  >> Yeah.
• 7:36
  >> In about August. It was.
• 7:38
  >> Were you jigggered when you got to the
• 7:40
  end?
• 7:40
  >> I was jigged before I started cuz we've
• 7:42
  been walking all day.
• 7:46
  >> Yeah, I can imagine. Um I think Charles
• 7:49
  is right actually.
• 7:51
  Uh look, it it may still
• 7:56
  I mean the the difference is really that
• 7:59
  if if we have a universe which is
• 8:02
  dominated by a constant
• 8:05
  uh um dark energy term. In other words,
• 8:08
  something that puts more energy into the
• 8:11
  expansion of space as the expansion as
• 8:14
  space gets bigger. Uh that means it will
• 8:16
  go on expanding forever. M
• 8:18
  >> um so and and Charles summarizes that by
• 8:21
  untold untold trillions beyond trillions
• 8:23
  which I guess is forever. Uh but if the
• 8:27
  dark energy is reducing and that's
• 8:30
  certainly being hinted at by the latest
• 8:32
  observations
• 8:33
  then um we don't know what what's going
• 8:38
  to happen because we don't know how
• 8:39
  quickly it's reducing and whether it may
• 8:42
  even go negative so that suddenly
• 8:44
  there's a positive attraction of stuff.
• 8:46
  it's not being repelled like it is now,
• 8:49
  that could bring it down to a few
• 8:50
  billion years. Uh but if it just goes
• 8:53
  settles back to something where it's the
• 8:56
  normal gravitational content of the
• 8:58
  universe that dominates everything, uh
• 9:01
  and so in other words, all the galaxies
• 9:02
  are pulling each other together. Uh then
• 9:05
  you you might be talking about a bit
• 9:07
  longer. It might still be a few trillion
• 9:09
  years rather than a few measly billions.
• 9:12
  Uh but uh interesting question, a nice
• 9:14
  thought experiment there from Charles in
• 9:16
  Brooklyn.
• 9:16
  >> Yes, indeed. And
• 9:19
  as you said, the the theory about when
• 9:22
  like I think I've said it before, when I
• 9:24
  was growing up, it was always assumed
• 9:26
  that the universe would stop expanding
• 9:28
  and then start sort of folding back in
• 9:30
  on itself.
• 9:31
  >> Uh the big crunch or the gab gibb,
• 9:34
  >> whatever you want to call it. But um
• 9:36
  then then it was decided that uh it was
• 9:39
  going to continue expanding at an
• 9:40
  accelerating rate. Now they've decided
• 9:43
  and and that could lead to a big rip.
• 9:45
  But now it's looking more like the
• 9:47
  acceleration is slowing
• 9:50
  and now all the bets are off and we're
• 9:52
  back to back to square one or something.
• 9:55
  I'm not sure. It's it's
• 9:57
  >> Yeah. How do you prove it?
• 9:59
  >> Well,
• 9:59
  >> I mean you you can you can Yeah. You you
• 10:02
  can measure that what's going on.
• 10:05
  get. Yeah.
• 10:06
  >> And and that's that's the trick. I mean,
• 10:08
  you know, if we'd been having this
• 10:09
  conversation a year ago, we'd have been
• 10:12
  >> completely sold on the the big rip
• 10:14
  because there was nothing to suggest
• 10:16
  that the expansion
• 10:17
  >> was going to slow down. The expansion
• 10:19
  was known to be accelerating. That was
• 10:21
  discovered in 1998.
• 10:23
  >> Um but it's only within the last year
• 10:25
  with um results from project called
• 10:27
  DESI. uh the dark energy survey
• 10:31
  instrument I think is the right thing.
• 10:34
  Uh but that's basically established that
• 10:39
  established is the wrong word. It has
• 10:40
  suggested that the acceleration is
• 10:44
  slower now than it was a couple of
• 10:46
  billion years ago.
• 10:48
  >> Yeah. uh and that uh is leading people
• 10:52
  to the hint that maybe the acceleration
• 10:54
  will eventually not be there and that's
• 10:56
  why we might get the gab gibb. But I
• 10:58
  think we are we're still talking about I
• 11:00
  think really think it's trillions of
• 11:02
  years into the future.
• 11:03
  >> It's like blowing up a balloon though
• 11:05
  when you start it goes out fast but as
• 11:07
  it gets bigger the expansion continues
• 11:10
  but it just it slows down. It's the same
• 11:13
  thing.
• 11:16
  >> Okay.
• 11:19
  Maybe not. It does remind me um we we
• 11:22
  got a question in German the other day
• 11:25
  because apparently now what they're
• 11:27
  doing on YouTube, the people who listen
• 11:28
  to us on YouTube is uh it's now
• 11:32
  English-speaking
• 11:34
  YouTube podcasts are being translated
• 11:37
  into other languages. So apparently we
• 11:41
  were being heard in German and a German
• 11:43
  listener on YouTube sent us a question
• 11:46
  in German and we had to translate it
• 11:50
  into English so that we knew what he was
• 11:52
  asking. But I don't think it translated
• 11:53
  very well. But it was something about
• 11:56
  how do you prove the expansion of the
• 11:58
  universe if you haven't found a
• 12:01
  particle?
• 12:02
  >> Well, I I wasn't sure whether I I I did
• 12:05
  look at that question. And in fact, I
• 12:06
  did send an answer which I think um you
• 12:08
  might have put through some language
• 12:10
  mangling s um system to give a the
• 12:14
  answer in German. Uh mut's
• 12:18
  crap. Uh so um so that's K K R Ap. It's
• 12:24
  not
• 12:27
  >> uh um so um I think I wasn't sure
• 12:30
  whether it was somebody talking about
• 12:33
  dark energy or dark matter. Yeah, I
• 12:35
  wasn't sure either.
• 12:36
  >> But dark matter, yes, we do need to know
• 12:38
  what the particles are. And um I hope
• 12:41
  we'll discover them. I I'm not
• 12:42
  optimistic. We're going to find that out
• 12:44
  during 2026, but you never know.
• 12:47
  Anything's possible.
• 12:48
  >> Thanks for your question, Charles. This
• 12:50
  is Space Nuts uh Q&A edition with Andrew
• 12:53
  Dunley and Fred Watson.
• 12:56
  >> Now, let's take a break from the show to
• 12:57
  tell you about our sponsor, NordVPN.
• 13:00
  Now, I think we all agree that exploring
• 13:02
  the universe is thrilling. But exploring
• 13:05
  the internet without protection,
• 13:08
  that's a black hole you don't want to
• 13:09
  fall into. Sorry. Uh, as a Space Nuts
• 13:13
  listener, we have an exclusive deal for
• 13:15
  you so you can stay protected, and that
• 13:17
  is NordVPN. It's the fastest, most
• 13:20
  secure way to browse the web. With
• 13:23
  NordVPN, you get next level encryption,
• 13:27
  blazingly fast servers around the world,
• 13:30
  and zero tracking, so you can stream,
• 13:32
  shop, or scroll safely. Uh, it's the
• 13:36
  tool I personally trust when we're
• 13:39
  diving into the internet and um, we want
• 13:42
  to give you peace of mind. Uh, I've used
• 13:45
  it overseas several times. I've used it
• 13:47
  at home. It works and it is seamless.
• 13:51
  Uh, head to nordvpn.com/spacenuts
• 13:54
  for an exclusive deal just for Spacenuts
• 13:57
  listeners. Big savings plus 4 months
• 14:00
  extra absolutely free. Don't surf the
• 14:03
  cosmos unshielded. Uh, secure your
• 14:06
  digital universe today with
• 14:08
  nordvpn.com/spacenuts.
• 14:11
  And don't forget their 30-day money back
• 14:14
  guarantee. Go to nordvpn.com/spacenuts.
• 14:21
  >> Three, two, one.
• 14:24
  >> Spacenuts. Uh, next up we've got Dean
• 14:27
  who's got a kind of a what if question
• 14:30
  for I love these Fred. These are my
• 14:32
  favorite questions. What if this
• 14:34
  happens?
• 14:35
  >> Hi Fred and Andrew. This is Dean in
• 14:36
  Redcliffe in Queensland. Thanks for
• 14:38
  answering my previous questions. Today
• 14:41
  I'm asking about a thought experiment
• 14:43
  that was once used to consider issues
• 14:45
  around the speed of light. I think it
• 14:47
  may have been Einstein. The scenario
• 14:49
  asks, "What happens if our sun suddenly
• 14:51
  disappears? And would the sudden lack of
• 14:54
  gravity affect the earth instantly or
• 14:56
  would there be a delay if the gravity
• 14:58
  effect travels at a particular speed?"
• 15:01
  Before I get to my actual question, I
• 15:03
  want to ask about thought experiments.
• 15:05
  They seem like a useful tool to get
• 15:07
  started on a problem, but I question the
• 15:09
  value of an experiment where the initial
• 15:12
  proposition is impossible.
• 15:14
  The mass of the sun can't actually just
• 15:16
  disappear. So maybe basing conclusions
• 15:19
  from this is not reliable. What are your
• 15:21
  thoughts? However, if I just focus on
• 15:24
  the idea of the sun disappearing, I'd
• 15:26
  say that gravity is not a force
• 15:28
  generated by the sun, but is a
• 15:30
  compression of the spaceime around it.
• 15:32
  If the sun disappeared instantly, then
• 15:35
  spacetime would decompress back to a
• 15:38
  smooth state except for the planets and
• 15:40
  moons still in the vicinity. There would
• 15:43
  also have to be an unwinding of the
• 15:44
  frame dragging around where the sun was.
• 15:47
  Let me know if I'm wrong, but it seems
• 15:49
  to me that a sudden decompression and
• 15:52
  unwinding of some local spacetime would
• 15:54
  be violent, but would not be instant.
• 15:57
  Imagine the 2D model of this using a
• 16:00
  large rubber sheet with a heavy ball in
• 16:02
  the center representing the sun. If you
• 16:04
  suddenly removed the ball, then the
• 16:07
  warped sheet would snap back into a flat
• 16:09
  plane quickly, but not instantly.
• 16:13
  Spacetime is very stiff. Maybe the Earth
• 16:16
  would start to feel some effect very
• 16:19
  quickly, but there would be a smooth
• 16:21
  transition to the complete lack of sun's
• 16:25
  gravity while the local spaceime is
• 16:26
  settling into a decompressed state. I
• 16:29
  also expect there would be a compression
• 16:31
  wave i.e. a gravity wave generated from
• 16:34
  an event like this. What do you think?
• 16:39
  There's a lot packaged into that. Uh
• 16:41
  thank you Dean. Uh so there's a question
• 16:44
  or two questions effectively uh that
• 16:46
  he's asking about. Um what's the worth
• 16:49
  of thought experiments? Uh now
• 16:54
  yeah
• 16:56
  I I just did a little bit of research
• 16:58
  while I was listening to him and that to
• 17:00
  give you an idea of thought experiments
• 17:02
  u there have been many famous ones over
• 17:04
  the years. Schroinger's cat. Uh,
• 17:07
  Galileo's falling bodies.
• 17:10
  Um, there's one called the trolley
• 17:12
  problem. I have to look into that. Don't
• 17:14
  know what that one is. But, um, yeah,
• 17:16
  they have been very helpful over the
• 17:18
  years. I I do think there is worth in
• 17:21
  thought experiments. It's a way of
• 17:23
  exploring something that we can't solve
• 17:25
  yet because we haven't got the
• 17:26
  technology to solve it. uh it gives you
• 17:30
  something to work with and it tosses
• 17:32
  around ideas that may provide solutions.
• 17:35
  It's um I think I yeah I I love I love
• 17:39
  the concept. I think it's very valuable.
• 17:41
  If it's how we start making inquiries
• 17:44
  with thought experiments, you know, if
• 17:46
  we if we didn't use our imaginations,
• 17:48
  then we probably wouldn't solve
• 17:49
  anything.
• 17:51
  >> Exactly. Um a great answer actually,
• 17:54
  Andrew. Thank you. I um I I'll I'll just
• 17:56
  go home and talk about
• 17:59
  No, I I entirely agree. Um the one that
• 18:01
  came to my mind was a thought experiment
• 18:03
  that had it had the real experiment been
• 18:06
  carried out, uh physics would have grown
• 18:08
  to a halt very quickly. And that's uh uh
• 18:11
  Einstein's musing in 197
• 18:15
  about what would happen if he jumped off
• 18:17
  the top of the patent building in Burn,
• 18:20
  which is where he was working at the
• 18:21
  time. He was a patent administrator.
• 18:24
  Uh and so he imagined himself jumping
• 18:26
  off the top of the building. Uh so if he
• 18:28
  carried that out as a real experiment,
• 18:30
  that could have been the end of a lot of
• 18:31
  really good stuff.
• 18:32
  >> Yeah.
• 18:33
  >> Uh so uh but what it gave him was the
• 18:36
  inspiration
• 18:37
  uh to um define what we now call the
• 18:40
  principle of equivalence. The fact that
• 18:43
  acceleration and gravity are to all
• 18:46
  intents and purposes the same. Um so and
• 18:50
  the fact that you're accelerating
• 18:51
  towards the earth uh cancels out the
• 18:54
  earth's gravity because the two are
• 18:56
  exactly equal. And that's why as you as
• 18:58
  you you know as you jump off the
• 19:00
  building uh your pipe floats out of your
• 19:02
  mouth if you've got money in your hands
• 19:04
  or something like that it just floats
• 19:05
  away. You can actually demonstrate it
• 19:07
  very easily on a trampoline.
• 19:08
  >> Yes.
• 19:09
  >> Uh without jumping off buildings. But it
• 19:11
  was that thought experiment that led to
• 19:12
  the principle of equivalence which told
• 19:15
  Einstein that gravity is actually a
• 19:17
  geometrical problem rather than you know
• 19:20
  something entwined in physics. We know
• 19:23
  it is we still don't really understand
• 19:25
  the physics of gravity but the geometry
• 19:27
  works so well uh in the general theory
• 19:31
  of relativity that um the principle of
• 19:34
  equivalence has been demonstrated to be
• 19:36
  accurate to within one part in 10 to the
• 19:38
  18 or something. I can't remember what
• 19:40
  the latest the latest thing is uh that
• 19:42
  it does work very very well indeed. Uh
• 19:45
  so yes, thought experiments are great.
• 19:47
  Um now the thought experiment regarding
• 19:49
  taking the sun out the solar system is
• 19:51
  very well established as to what
• 19:53
  happens. Uh the the earth feels nothing
• 19:56
  for the first eight minutes. Uh because
• 19:59
  gravitational energy travels at the same
• 20:01
  speed as light. uh and once uh the the
• 20:05
  message that there is no gravitating
• 20:07
  gravitating body in the center of the
• 20:09
  solar system reaches the earth 8 minutes
• 20:12
  after the sun has gone um the earth just
• 20:14
  carries on in a straight line.
• 20:17
  >> Uh uh so that's uh that's well
• 20:20
  understood. So I think um I think uh um
• 20:25
  Dean's um uh thinking about the you know
• 20:29
  the the two-dimensional idea of the
• 20:31
  gravity well which is a great way of
• 20:33
  thinking of the way uh mass distorts
• 20:36
  time. Uh we're we're used to thinking
• 20:39
  okay you've got a a rock in the middle
• 20:41
  of a trampoline it's pulling it down.
• 20:43
  You take the rock away the trampoline
• 20:44
  just springs back. Uh but actually uh it
• 20:47
  wouldn't the spacetime would take uh
• 20:50
  time uh the the basically the message
• 20:53
  that it had sprung back would take would
• 20:55
  travel outwards at the speed of light.
• 20:57
  Uh and so it's the same you know the
• 21:00
  same thing looking at it either as a
• 21:01
  gravity well or as gravitational energy
• 21:05
  or radiation. One day we'll have a
• 21:07
  quantum theory of gravity and we'll be
• 21:08
  able to talk about gravitons uh which
• 21:10
  are the hypothetical particles that
• 21:12
  carry gravity and they move at the speed
• 21:14
  of light. Of course, you we we should
• 21:16
  mention the catastrophe that would then
• 21:18
  follow eight minutes after the the sun
• 21:20
  suddenly disappeared. For example,
• 21:22
  Pavlov's dog and Schroing Schroinger's
• 21:25
  cat would live together.
• 21:26
  >> Yes.
• 21:28
  >> So, they would Yeah. Oh, dear me. That's
• 21:32
  Yes. That
• 21:33
  >> would be would be a mess.
• 21:35
  >> Things are good.
• 21:36
  >> Well, how long would the Earth last
• 21:38
  after that effect?
• 21:39
  >> Uh, it would be fine. It would just keep
• 21:41
  on going. um you know assuming there
• 21:43
  wasn't some sort of um uh catastrophic
• 21:46
  event that caused the sun to disappear.
• 21:48
  If you just remove the sun without
• 21:50
  anything explosive or and anything which
• 21:52
  you could do in a thought experiment um
• 21:55
  the earth just keeps keeps on going. It
• 21:57
  would be like Voyager one and Voyager 2.
• 21:58
  It will get very very cold. Uh we as a
• 22:01
  species would almost certainly not
• 22:02
  survive. No.
• 22:03
  >> Uh because the temperatures would
• 22:05
  plummet to very low levels indeed. Um,
• 22:08
  so yes, an interesting scenario.
• 22:12
  >> Doesn't sound like much fun.
• 22:13
  >> It's not fun. No.
• 22:14
  >> No. Anyway,
• 22:15
  >> think about it, though.
• 22:16
  >> We're we're stuck with um with the sun
• 22:19
  for several more billion years.
• 22:22
  >> Yes, indeed we are.
• 22:24
  >> Yeah. But, uh, great questions, Dean. I
• 22:27
  really enjoy those kinds of questions.
• 22:29
  So, uh, yeah, thanks for sending it in.
• 22:33
  >> Let's take a break from the show to tell
• 22:34
  you about our sponsor, Anti-gravity. A1.
• 22:38
  Have you ever wished you could actually
• 22:40
  feel what it's like to fly? Not just
• 22:42
  control a drone from the ground, but
• 22:44
  truly experience the air around you.
• 22:47
  Well, that future has just arrived.
• 22:50
  Introducing the Anti-gravity A1, the
• 22:52
  world's first all-in-one 8K 360 drone,
• 22:56
  and it's officially available now. Uh,
• 23:00
  this isn't just another drone. It's an
• 23:01
  entirely new category. The camera is
• 23:04
  unreal. Anti-gravity A1 captures 8K full
• 23:09
  360 degree video on every flight. No
• 23:12
  missed shots, no worrying about gimbals
• 23:15
  or lining up angles. Just fly first,
• 23:18
  frame later. You can create cinematic
• 23:21
  pans, add special effects, or achieve
• 23:25
  perfectly stabilized action footage
• 23:27
  thanks to the flow state stabilization.
• 23:30
  And the whole drone weighs in at just
• 23:33
  249 g. That means travel ready,
• 23:37
  regulation friendly, and it fits in the
• 23:39
  palm of your hand. The anti-gravity A1
• 23:42
  is now available in three bundles at the
• 23:44
  anti-gravity store, Best Buy, and
• 23:46
  authorized retailers worldwide. So, if
• 23:49
  you ever wanted to rethink what a drone
• 23:51
  can be or what flight can feel like,
• 23:54
  check out the Anti-gravity A1. Just tap
• 23:57
  on the link in the show notes.
• 24:00
  3 2 1
• 24:03
  >> Space nuts. Our final question today
• 24:07
  comes from Patrick. He's a conspiracy
• 24:09
  theorist. Well, he's probably not, but I
• 24:11
  I do like this question because I I
• 24:13
  didn't know this. Uh the Voyager
• 24:16
  spacecraft have plaques on them. I did
• 24:18
  know that. And as far as I can find out,
• 24:21
  both show them leaving the solar system
• 24:23
  ecliptic uh between Jupiter and Saturn.
• 24:27
  That didn't happen. And from what I've
• 24:30
  read, Voyager 1 left after a visit to
• 24:32
  Titan while Voyager 2 carried on. Uh
• 24:36
  Voyager 1 has a chance to visit uh had a
• 24:39
  chance to visit Pluto. So here's the
• 24:41
  questions. Why does the plaque show an
• 24:43
  early departure of Voyager 1 and why
• 24:46
  does Voyager 2's path show the same? Um
• 24:49
  hope you both had a wonderful Christmas
• 24:52
  and um hello from a wet northern island,
• 24:56
  Patrick. wet Northern Ireland. It's
• 24:59
  probably still wet just like we're still
• 25:01
  dry. This we've hit the hottest driest
• 25:03
  part of the year in Australia and um it
• 25:06
  is it is dry as a chip as we say in this
• 25:09
  country at the moment. Um yeah. Okay. I
• 25:13
  I didn't realize that the plaques had
• 25:15
  the supposed path of both spacecraft,
• 25:18
  but they didn't go that way. Um did they
• 25:20
  get pulled over by an RBT perhaps?
• 25:24
  Um, I thought you'd have spotted this
• 25:27
  one right at the start, Andrew.
• 25:29
  >> Really?
• 25:32
  >> Is he playing us?
• 25:33
  >> No. Uh, no. He's He's got his spacecraft
• 25:36
  mixed up because it's the two the two
• 25:38
  pioneers that show the spacecraft
• 25:41
  leaving the solar system between the
• 25:43
  orbits of Jupiter.
• 25:45
  >> I never even thought of that.
• 25:48
  >> Voyager doesn't actually have a diagram
• 25:49
  like that on it. He's got mostly
• 25:51
  diagrams how to play the golden record.
• 25:53
  >> That's right.
• 25:54
  >> Um, so it's the Pioneer spacecraft. So
• 25:57
  Patrick, you your your question's a good
• 26:00
  one, but I think the premise is wrong.
• 26:03
  It's it's not the Voyager spacecraft
• 26:04
  that had the diagram. It's the Pioneers.
• 26:06
  >> Well, how about that?
• 26:09
  >> Yeah, I'm just looking at them now.
• 26:11
  Okay,
• 26:13
  that's really And it's got the the human
• 26:16
  being on it and all that.
• 26:17
  >> I actually really like the Pioneer uh
• 26:19
  plugs. I think they're
• 26:20
  >> elegant and decorative and
• 26:23
  >> uh tell the story just show aliens just
• 26:26
  how
• 26:27
  >> chewy we are and you know
• 26:29
  >> how tasty we might be
• 26:31
  >> and how um unfortunate that male
• 26:33
  appendages. It's um it's well below par.
• 26:36
  But um
• 26:38
  and the other the other factor is that
• 26:41
  um
• 26:41
  >> thanks Andrew.
• 26:42
  >> Aliens will look at these two human
• 26:44
  figures and they'll go she does not like
• 26:48
  him. that.
• 26:49
  >> Yeah, that's right.
• 26:51
  >> The body language is not positive.
• 26:54
  >> That's true. There is body language on
• 26:55
  there that really Yeah, I I'm with you
• 26:58
  on that actually.
• 27:01
  >> It's all about body language. Yeah.
• 27:03
  >> So, now I'm going to have to look up
• 27:04
  what the Voyager plaques look like.
• 27:07
  >> Yeah.
• 27:08
  >> Ah, see it's Yes. It's the golden record
• 27:10
  with the um um bits and bobs on them
• 27:13
  >> stuff on it. Yeah. Yeah.
• 27:15
  >> Okay.
• 27:17
  So, um, right idea, wrong wrong
• 27:20
  spacecraft is basically the answer to
• 27:22
  the question.
• 27:24
  >> Uh, I think that's correct. So,
• 27:26
  >> yeah. So,
• 27:27
  >> and, um, look,
• 27:28
  >> I think we can safely say that Voyager 1
• 27:30
  and Voyager 2 did go where we intended
• 27:32
  them to.
• 27:32
  >> Yes, they did.
• 27:33
  >> Go.
• 27:34
  >> And they're still going.
• 27:35
  >> Yeah, indeed they are. Voyager 2, well,
• 27:37
  Pioneer 10 and 11 are as well. Uh,
• 27:39
  Voyager 2 was the one that flew by
• 27:41
  Uranus and Neptune as well as Jupiter
• 27:44
  and Saturn. fantastic details that came
• 27:46
  from those two spacecraft. As Voyager
• 27:49
  One, as we've said many times before, is
• 27:51
  the most distant human-made object and
• 27:55
  is still on its way. It's almost a light
• 27:58
  day away. We should have a little party
• 27:59
  at Space Nots when it crosses a light
• 28:01
  day uh the light day boundary.
• 28:04
  >> Yeah. Which is happening in about 500
• 28:07
  years from now. No, I'm not sure.
• 28:08
  >> It's uh can't be that far away.
• 28:10
  >> Yeah, it's a few years. Yeah, a couple
• 28:12
  of years. I think
• 28:12
  >> it's about 23 light hours at the moment.
• 28:15
  Uh so it'll be Yeah. four or five years
• 28:18
  and
• 28:18
  >> Yeah. Wow. Yeah. But we should do
• 28:20
  something special about that.
• 28:21
  >> We should do that.
• 28:22
  >> Yes.
• 28:23
  >> All right. Um well, that was easily
• 28:25
  solved. Thanks for the question, though,
• 28:26
  Patrick. It sort of Yeah, it reminds us
• 28:29
  that as time goes on, you can sort of
• 28:31
  mix two totally different things
• 28:34
  together and yeah, it throws throws your
• 28:38
  brain out. Um, it reminds me of a story
• 28:41
  once where um, oh gosh, a guy I worked
• 28:45
  with in radio did a special about um,
• 28:49
  uh, Dean Martin and Jerry Lewis getting
• 28:51
  back together. Remember them? Yeah.
• 28:53
  >> Yeah. But he thought it was Jerry Lee
• 28:55
  Lewis and
• 28:57
  >> so he did this whole special with Jerry
• 28:59
  Lee Lewis music and
• 29:01
  >> it completely wrong.
• 29:04
  >> Yes.
• 29:04
  >> But it can happen.
• 29:06
  >> It can happen. Yeah. I um Yes, I looked
• 29:10
  at some research recently where they'd
• 29:11
  got the wrong telescope. Uh
• 29:14
  >> yeah, it's like getting the color of the
• 29:16
  universe wrong when you make
• 29:17
  >> That's another one. That's correct. Yes.
• 29:19
  Yeah.
• 29:20
  >> Oh, there's a list of them. There's a
• 29:22
  list of them. So, don't feel bad,
• 29:24
  Patrick. It happens to the best of us.
• 29:27
  >> Uh but thanks for the question. Lovely
• 29:28
  to hear from you. If you've got
• 29:29
  questions for us, please send them in to
• 29:31
  us via our website. Just go to
• 29:34
  spacenutspodcast.com
• 29:36
  or spacenuts.io
• 29:38
  if you're a lazy typist and click on the
• 29:41
  AMA button up the top and you can send
• 29:44
  us text and audio questions that way. Uh
• 29:47
  we sometimes get them through YouTube.
• 29:49
  So if you're YouTube listener, please uh
• 29:51
  send them in. Um be happy to hear from
• 29:53
  you. Uh and uh don't forget reviews. We
• 29:56
  we really appreciate your reviews. The
• 29:58
  more reviews the better. Um, I mean it's
• 30:01
  an astronomy podcast, so you know, um,
• 30:04
  five stars would be the absolute
• 30:06
  minimum, I would expect. That's up to
• 30:09
  you. No influence here. No influence
• 30:12
  here.
• 30:12
  >> 4 million stars. That's
• 30:13
  >> 4 million stars. Yes. Deal.
• 30:16
  >> Uh, and um, yeah, if you'd like to do
• 30:18
  that for us, that' be great. And don't
• 30:20
  forget to um check out our website. Uh,
• 30:22
  if you want to uh support us, um, some
• 30:25
  people do through um, Patreon and and
• 30:27
  Supercast. Uh there's a little button
• 30:30
  where it it says support our podcasts.
• 30:33
  So click that button. You can find out
• 30:34
  more about it. It's totally voluntary.
• 30:37
  Uh Fred, we are done. Thank you so much
• 30:39
  for answering those questions.
• 30:40
  >> Oh, it's a pleasure. It's um always good
• 30:42
  to interact with our four listeners.
• 30:47
  >> We've only got four at a time.
• 30:50
  >> Yeah. No, it's good. And thank you very
• 30:52
  much again as always, Andrew, for being
• 30:55
  the host of Space Notes.
• 30:56
  >> Oh, my great pleasure. It's good fun.
• 30:58
  Uh, Professor Fred Watson, astronomer at
• 31:00
  large. He'll join us again on the next
• 31:02
  episode. Uh, and Hugh in the studio,
• 31:04
  couldn't be with us today because he was
• 31:06
  doing a thought experiment.
• 31:09
  Uh, where he didn't exist.
• 31:13
  What more can I say? Uh, and from me,
• 31:15
  Andrew Dunley, thanks for your company.
• 31:17
  We'll catch you on the next episode of
• 31:18
  Space Nuts. Bye-bye.
• 31:20
  >> Space Nuts. You've been listening to the
• 31:22
  Space Nuts podcast
• 31:25
  >> available at Apple Podcasts, Spotify,
• 31:28
  iHeart Radio, or your favorite podcast
• 31:31
  player. You can also stream on demand at
• 31:33
  byes.com. This has been another quality
• 31:36
  podcast production from byes.com.