Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / Quantum Light, Expanding Universes & Black Hole Mysteries: #502 - Answering Your Most Intriguing Questions

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Quantum Light, Expanding Universes & Black Hole Mysteries: #502 - Answering Your Most Intriguing Questions · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Andrew Dunkley: Hi there. Thanks for joining us on a Q and A
• 0:02
  edition of Space Nuts. My name is Andrew
• 0:05
  Dunkley. It's always good to have your
• 0:07
  company. Thanks for joining us. All right,
• 0:10
  uh, what are we doing today? We're answering
• 0:11
  audience questions from all around the place.
• 0:15
  Well, mainly Australia, but one from New
• 0:17
  Orleans asking about black holes and plasma
• 0:19
  bursts. Uh, and Jordy wants to know where
• 0:22
  his food is. Uh, we're also talking about the
• 0:25
  minimum temperature of space, the effect of
• 0:27
  gas or on light and the
• 0:30
  starshot mission. That's all coming up in
• 0:32
  this edition of space nuts.
• 0:34
  Voice Over Guy: 15 seconds. Guidance is internal.
• 0:37
  10, 9. Ignition
• 0:39
  sequence start. Space nuts.
• 0:41
  Andrew Dunkley: 5, 4, 3. 2.
• 0:43
  Professor Fred Watson: 1, 2, 3, 4, 5, 5, 4, 3,
• 0:46
  2, 1. Space nuts. Astronauts report
• 0:49
  it feels good.
• 0:50
  Andrew Dunkley: And joining us along with Jordy, not Jaunty
• 0:53
  Joe Jordy. Uh, it's professor Fred Watson,
• 0:55
  astronomer at large. Hello, Fred.
• 0:57
  Professor Fred Watson: Hello, Andrew. Uh, yes, John. Um, John,
• 1:00
  Jordy's in the back.
• 1:03
  Johnty's not. Yeah,
• 1:06
  Jordy the dog.
• 1:08
  Andrew Dunkley: He's um, he's always welcome on the show.
• 1:10
  Always welcome on the show.
• 1:12
  Professor Fred Watson: Yeah, he had a good walk with me this
• 1:14
  morning. I, I'm good fettle.
• 1:16
  Andrew Dunkley: I'm sure he did. Um, now you're so
• 1:18
  tall and he's so small, I bet his legs go 20
• 1:21
  to the dozen.
• 1:22
  Professor Fred Watson: M quite cute to watch.
• 1:25
  Andrew Dunkley: Be like a little wind up.
• 1:27
  Professor Fred Watson: It's what it's like. Yeah, absolutely.
• 1:29
  Andrew Dunkley: Oh, gosh.
• 1:31
  Um, now I, I, I, we, we, we've got some
• 1:33
  questions, a couple of text and a couple of
• 1:35
  audio. Now I uh, must, uh,
• 1:38
  preempt this by saying I had an eye
• 1:41
  check this morning and I had to have my
• 1:43
  pupils dilated. Right now what I'm looking
• 1:46
  at is absolute gobbledygook
• 1:49
  and it's very hard for me to read.
• 1:51
  Professor Fred Watson: So please, you want me to read it?
• 1:54
  Andrew Dunkley: I'll give it a go.
• 1:55
  Professor Fred Watson: Give it a go.
• 1:56
  Andrew Dunkley: Yeah, everything's, it's all double vision
• 1:59
  and blurry. Um, but anyway, let's, let's
• 2:02
  see what, uh, happens.
• 2:03
  Uh, this question comes from Jim in New
• 2:05
  Orleans. I read where the Hubble
• 2:08
  telescope last fall. I assume you mean
• 2:11
  autumn for the people in the rest of the
• 2:13
  world. Um, I read where the Hubble telescope
• 2:15
  last fall observed what appeared to be a
• 2:17
  plasma beam of 3,000 light years emanating
• 2:20
  from, from the black hole at the center of
• 2:22
  Galaxy M M87 doing well so
• 2:25
  far. That black hole was
• 2:27
  estimated to be 6.5 billion
• 2:30
  solar masses. I realized that questions
• 2:33
  concerning black holes are rather rare.
• 2:36
  Uh, on the podcast, however, I
• 2:39
  understand that When a plasma, uh, cools
• 2:41
  on Earth, it can either return to its
• 2:43
  original, original gaseous elemental
• 2:46
  state, or it can potentially reform into
• 2:49
  completely different elements. Given the near
• 2:51
  absolute zero temperatures in space, I
• 2:54
  believe that at some point the plasma beam
• 2:57
  from, uh, uh, the uh,
• 3:00
  black hole at M. M87 will eventually cool.
• 3:03
  Rather than being cursed as the ultimate
• 3:05
  destroyer of matter in the universe, perhaps
• 3:08
  black holes should be considered the ultimate
• 3:10
  recyclers of matter instead. Love
• 3:13
  the podcast. Uh, all the best. Cheers.
• 3:16
  Jim in New Orleans. Uh,
• 3:19
  is he on the money?
• 3:20
  Professor Fred Watson: Well, it's an interesting question. Yes. Uh,
• 3:23
  I mean, I think he's, he's right in the
• 3:25
  sense that the plasma, when it
• 3:28
  cools, um, will,
• 3:31
  uh, essentially turn, you know,
• 3:34
  what's a plasma? A plasma is an ionized gas.
• 3:37
  So it's a gas with an electrical charge. It's
• 3:39
  an electrified gas. When it loses its
• 3:42
  charge, it basically stays the same
• 3:45
  gas, uh, but is
• 3:47
  cooler. Uh, now the completely
• 3:50
  different elements idea would involve nuclear
• 3:53
  processes because, uh, that's the only way
• 3:56
  you can change the elements, despite
• 3:59
  what the, um, what the alchemists used to try
• 4:01
  and do. Uh, you can do it with
• 4:03
  accelerators. Uh, and it may well be
• 4:06
  that, uh, the conditions in some plasmas,
• 4:09
  like the one from the M87 black hole, maybe
• 4:12
  they do, um, have collisions
• 4:15
  between the, uh, the ionized
• 4:17
  atoms, uh, that are of such high
• 4:20
  energy that you might split them or something
• 4:22
  of that. So I'm not familiar with that
• 4:25
  because I'm not a particle physicist, but in
• 4:27
  that regard, yes, if that happens, you've
• 4:29
  got, uh, a nice recycling process
• 4:32
  which, um, you know, is what goes on in a
• 4:34
  nuclear reactor as well. Uh, but nice
• 4:37
  to hear from you, Jim. Uh, glad you're
• 4:38
  enjoying the podcast too.
• 4:40
  Andrew Dunkley: Yeah, um, there's so much happening when it
• 4:43
  comes to black holes. I mean, there's just.
• 4:45
  Yes, you know, it's not just the plasma.
• 4:48
  It's, it's um,
• 4:51
  you know, the hunger, if I can use that
• 4:54
  term, black holes, uh, they get the
• 4:56
  munchies. They probably smoke too much pot.
• 4:59
  Professor Fred Watson: Um, is that what happens when you smoke too
• 5:01
  much pot?
• 5:02
  Andrew Dunkley: Apparently, I've been told, yeah. Yeah,
• 5:05
  Medical paper once,
• 5:08
  I spent a lot of time reading those.
• 5:11
  Um, but yeah, they're very active,
• 5:14
  um, parts of the, the
• 5:16
  universe. And there's so much we know that
• 5:19
  they do, but we don't know so much more about
• 5:22
  them. And we've, uh, only in recent times
• 5:25
  been able to image them. Yep, not so much
• 5:28
  photographs, but, um, it, uh, was infrared,
• 5:31
  wasn't it?
• 5:31
  Professor Fred Watson: That's Radio signals in the Event
• 5:34
  Horizon Telescope. That's right. And that's
• 5:36
  where this image comes from that, that Jim's
• 5:38
  talking about.
• 5:39
  Andrew Dunkley: Okay, so, um, yeah, the.
• 5:42
  And, and we get so very many
• 5:45
  questions about them. They. One of the great
• 5:47
  mysteries. Sorry.
• 5:49
  Professor Fred Watson: And I'll just correct what I just said. Uh,
• 5:51
  the, the Hubble telescope is certainly,
• 5:54
  um, what observed that, uh, plasma
• 5:57
  beam. Uh, but M87, of
• 5:59
  course, has had its, its structure, uh,
• 6:02
  imaged by the Event Horizon Telescope. Sorry,
• 6:05
  just. Just correcting myself there.
• 6:07
  Andrew Dunkley: That's okay. It's all good. Thank you, Jim.
• 6:10
  Professor Fred Watson: Appreciate.
• 6:10
  Andrew Dunkley: Uh, the question.
• 6:11
  Uh, our next question comes from, uh, one of
• 6:13
  our regulars, Buddy. Uh, we'll
• 6:16
  see what, uh, he's got on his mind this time.
• 6:19
  Buddy: Well, hello. This is Buddy from
• 6:21
  Morgan. All right, guys, um, I
• 6:24
  got one more good one. I'll leave you alone
• 6:26
  for a while. Uh,
• 6:29
  is the minimum temperature of space,
• 6:32
  like, in the dark? Uh, is that gonna get
• 6:35
  lower as the universe spreads out? And
• 6:38
  if so, is that going to affect how things
• 6:40
  root in the universe react? Like, is that
• 6:43
  going to make the hydrogen or, you
• 6:46
  know, like helium turn into a liquid or
• 6:48
  something? Um, all right, thanks,
• 6:50
  guys.
• 6:52
  Andrew Dunkley: Uh, thank you, Buddy. Um, so as the
• 6:55
  universe is expanding, is the minimum
• 6:58
  temperature of space going to get lower? And
• 7:00
  what effect might that have on the elements?
• 7:03
  I think that's sort of the pricey.
• 7:05
  Professor Fred Watson: That's a nice pricey. Um, and,
• 7:08
  uh, Buddy's rice, it is getting
• 7:10
  lower. Uh, so, uh,
• 7:13
  the minimum temperature of space is
• 7:17
  essentially the temperature, uh, that we
• 7:19
  record from the cosmic background radiation,
• 7:22
  which is 2.7 degrees above absolute
• 7:25
  zero. Uh, so 2.7 degrees
• 7:28
  Kelvin is the temperature of space. Uh,
• 7:31
  and, uh, if you think about
• 7:34
  what that temperature was when the universe
• 7:37
  was much younger than it is now,
• 7:40
  certainly, uh, in the aftermath of the Big
• 7:41
  Bang, that temperature was, you know, 5,
• 7:44
  6, 7,000 degrees Kelvin. So as
• 7:47
  the universe has expanded, that
• 7:50
  temperature has fallen. And that 2.7
• 7:52
  degrees is what we have now. And as the
• 7:55
  universe continues to expand, it will
• 7:57
  continue to cool, but not at a rate that
• 7:59
  would ever be detectable by human
• 8:01
  instruments. But it is cooling.
• 8:04
  Um, whether that changes the,
• 8:07
  you know, the circumstances of clouds of gas
• 8:10
  or whatever is a different question. And I
• 8:12
  suspect the answer is no. Uh,
• 8:16
  it may, you know, it would have a superficial
• 8:18
  effect, but I don't think it's got any
• 8:21
  really fundamental effect on the makeup of
• 8:24
  the, of the cosmos.
• 8:25
  Andrew Dunkley: Okay, um, let's focus
• 8:28
  on the, the Kelvin scale for a
• 8:31
  moment. Ah, it's, it's a measure of
• 8:34
  temperature based on the absolute,
• 8:37
  absolute zero, lowest temperature.
• 8:39
  Professor Fred Watson: That's right. And
• 8:42
  that temperature is defined by
• 8:45
  being the temperature at which all
• 8:48
  motion of atoms stops. So
• 8:51
  temperature is um, a vibration of
• 8:54
  atoms. So as a solid gets warmer, the
• 8:56
  atoms vibrate more. As a liquid gets warmer,
• 8:59
  the atoms sort of slosh around more. And
• 9:02
  as a gas gets warmer, the atoms whiz around
• 9:05
  much faster, uh, in space. So um,
• 9:09
  the three states of matter there, uh,
• 9:11
  that, uh, that's to say that
• 9:14
  um, uh, at, at zero degrees
• 9:17
  Kelvin, uh, all atomic motion
• 9:20
  stops and we know it's absolutely
• 9:22
  zero. I think, um, some modern laboratories
• 9:25
  have got within a gazillionth of a degree of
• 9:27
  absolute zero. But it's one of those things
• 9:29
  you can never actually reach, uh, and
• 9:32
  get something that's whose atoms have
• 9:34
  stopped. As far as I know. Um, I might be
• 9:36
  wrong there, there might be physics
• 9:37
  laboratories where that's actually been done.
• 9:39
  But.
• 9:39
  Andrew Dunkley: Right, well, if you have, you know, chances
• 9:41
  are if you did achieve it, you'd never get
• 9:43
  home from work. Quite, you wouldn't be able
• 9:45
  to move.
• 9:47
  Professor Fred Watson: Yeah, yeah.
• 9:48
  Andrew Dunkley: So, so obviously this is a dumb
• 9:51
  question, but, um, if you like, when you
• 9:54
  freeze a tray of ice in your fridge,
• 9:57
  you've got an old fashioned fridge like me
• 9:59
  where you have to actually get the thing out,
• 10:00
  fill it with water and put it in and.
• 10:02
  Professor Fred Watson: Wait, you do that too?
• 10:03
  Andrew Dunkley: Yeah. Um, that's not
• 10:06
  absolute zero. So there's still
• 10:08
  movement.
• 10:09
  Professor Fred Watson: Yeah. In the atoms.
• 10:10
  Andrew Dunkley: In the atoms, yes, that's right.
• 10:12
  Professor Fred Watson: Even though the ice looks pretty inert, uh,
• 10:15
  the fact that it's probably, uh,
• 10:18
  well, absolute zero is minus 273
• 10:20
  degrees Celsius. So if you're cooling it down
• 10:23
  to, you know, -13 or something, then you've
• 10:26
  still got another 260 degrees to
• 10:29
  go before you get to absolute zero. So
• 10:32
  there's still plenty of movement in the atoms
• 10:34
  of your ice. Yeah.
• 10:35
  Andrew Dunkley: What about out in the depths of the solar
• 10:37
  system where the ice is so cold
• 10:40
  that it's the same as rock
• 10:43
  here? Is that anywhere near absolute zero?
• 10:46
  Professor Fred Watson: It's about um, uh,
• 10:48
  minus 190 on the
• 10:51
  surface of Titan, which is where ice is
• 10:54
  certainly effectively rock. It's as hard as
• 10:56
  rock, uh, hard as granite I think
• 10:59
  was the way, um, Jonti described it last
• 11:01
  week. Yeah, um, but even then
• 11:04
  you still, you know, 83 degrees away from
• 11:07
  absolute zero. Wow. Uh, it's a very, very
• 11:10
  cold temperature.
• 11:11
  Andrew Dunkley: Sure is. Um, yeah, I,
• 11:14
  I, I, it's hard to imagine that kind of cold
• 11:17
  when the temperature outside here gets to 9
• 11:19
  degrees. That's enough for me.
• 11:21
  Professor Fred Watson: Yes, yeah,
• 11:23
  yeah.
• 11:24
  Andrew Dunkley: Uh, so just to clarify one more
• 11:27
  point. Um, um, so absolute
• 11:29
  zero. Even though the universe is
• 11:33
  cooling, absolute zero is still absolute
• 11:35
  zero. That's not going to alter.
• 11:37
  Professor Fred Watson: That's right. Yes, that's right. And, and the
• 11:40
  universe isn't at, uh, that temperature yet.
• 11:42
  It's 2.7 degrees above it still.
• 11:44
  Buddy: Okay.
• 11:45
  Professor Fred Watson: Yeah. And that's the leftover heat of the Big
• 11:47
  Bang.
• 11:48
  Andrew Dunkley: Right. But it's slowly diminishing
• 11:50
  as, as the universe expands.
• 11:52
  Professor Fred Watson: That's right.
• 11:53
  Andrew Dunkley: But it could take a while to get down.
• 11:55
  Professor Fred Watson: Could it ever get down another degree? It
• 11:58
  will probably. If the universe
• 12:01
  carries on behaving as it does now. Uh, as it
• 12:04
  continues to expand. Yep. The temperature
• 12:06
  will continue to go down. Uh, it will
• 12:09
  never reach absolute zero. It
• 12:11
  might approach it asymptotically, which means
• 12:14
  it gets nearer and nearer, but takes longer
• 12:17
  and longer to do that.
• 12:18
  Andrew Dunkley: Right, okay. Very interesting. Great
• 12:21
  question, buddy. Thanks for sending it in.
• 12:24
  Good to hear from you as always.
• 12:25
  This is Space Nuts, Andrew Dunkley here with
• 12:28
  Professor Fred Watson.
• 12:32
  Professor Fred Watson: Three, two, one.
• 12:35
  Andrew Dunkley: Space Nuts. Now, if my eyes do not
• 12:38
  deceive me, I have a text question in front
• 12:40
  of me. Or it could just be a message from my
• 12:42
  wife that I probably shouldn't read. Uh,
• 12:45
  no, it's a question. We know that light
• 12:48
  travels at slightly different speeds in
• 12:51
  different mediums. Uh, we also see different
• 12:54
  mediums affect light via refraction
• 12:57
  since this is somewhat related to the density
• 12:59
  of gas. Can pressure affect this?
• 13:02
  Uh, if we go to the extreme case, is it
• 13:05
  possible for enough pressure, ah, of a gas,
• 13:09
  I assume cloud, or enough pressure of
• 13:12
  a gas in general to push back on light
• 13:14
  itself and stop it? That comes from Jacob
• 13:17
  in Western Australia. Um, I
• 13:20
  assume Western Australia. It could be an
• 13:22
  American state that has the abbreviation Wa I
• 13:24
  believe there is one, so could be either.
• 13:27
  But um, this reminds me of an
• 13:30
  experiment they did not so long ago where
• 13:33
  they actually did claim to have stopped
• 13:36
  light.
• 13:37
  Professor Fred Watson: Yeah, that's right. Um, so you can
• 13:40
  stop photons. Um, and I'm
• 13:43
  not sure about the
• 13:46
  mechanism that is used to do that. It's not
• 13:48
  just pressure. There's more to it than
• 13:51
  that. I think it involves basically
• 13:54
  grabbing hold of photons using
• 13:56
  optical tweezers, uh, to stop the
• 13:59
  light. Uh, and so you can stop light. It's
• 14:02
  been done exactly as you've said, Andrew.
• 14:05
  But, uh, it's not just pressure. Pressures
• 14:07
  does have an interesting. I mean it does
• 14:09
  affect the gas. So refraction, the
• 14:12
  refraction of gas is invent, is affected by
• 14:15
  the pressure of the gas. Um, what
• 14:18
  also is affected Is
• 14:21
  if you send light of a single
• 14:23
  wavelength through a gas at
• 14:26
  high pressure, um, it will spread
• 14:29
  into adjacent wavelengths. It uh, means that,
• 14:32
  you know, the way we see it is as a spectrum
• 14:34
  line. If you send that light through a
• 14:37
  rain, sorry, a prism or something like
• 14:40
  that, you'll uh, end up with a single line of
• 14:42
  light corresponding to that color which
• 14:44
  corresponds to uh, a certain
• 14:47
  wavelength. Pressure actually broadens that
• 14:49
  and so these lines become wider.
• 14:52
  Uh, the process is called guess what?
• 14:55
  Pressure broadening. And um,
• 14:58
  um, that's what we see. Uh, and that's
• 15:00
  actually how we can use light, uh,
• 15:04
  from stars to measure the pressure in the
• 15:06
  atmosphere of the star, uh, by how much
• 15:09
  the line of light is
• 15:11
  broadened.
• 15:14
  Andrew Dunkley: Okay, okay. All right.
• 15:16
  Um, I was just reading something that,
• 15:19
  um, because we were talking about the fact
• 15:22
  that they have stopped light in a lab,
• 15:25
  um, the way they did it
• 15:27
  was um, they used, as you said, a
• 15:30
  special medium like um, a cloud of
• 15:33
  ultra cold atoms.
• 15:35
  Professor Fred Watson: Yes, that's right.
• 15:36
  Andrew Dunkley: Trapped the light's photons and it
• 15:39
  effectively brought the light to a complete
• 15:41
  standstill for a brief period. And that was
• 15:44
  work that was pioneered by physicists,
• 15:46
  um, uh, lean Howe,
• 15:50
  uh, from the Bose Einstein,
• 15:52
  um.
• 15:55
  Condensate. Condensate.
• 15:57
  Professor Fred Watson: Condensate, yeah.
• 15:58
  Andrew Dunkley: So, yes, your eyes aren't working.
• 16:01
  Professor Fred Watson: Yeah, well, you're doing well actually.
• 16:02
  You're doing very well. If I, um. The eyes
• 16:04
  that you've got at the moment, I couldn't
• 16:05
  read any of the stuff that you're looking at.
• 16:08
  A, um, Bose Einstein condenser is
• 16:10
  basically, uh,
• 16:13
  it says peculiar state of matter
• 16:16
  where it behaves as a single quantum object.
• 16:19
  Uh, so you know, you put all the atoms
• 16:22
  together and they all behave like one object.
• 16:24
  It's a bit like entanglement.
• 16:26
  Andrew Dunkley: Right. It's headache y stuff, isn't it?
• 16:29
  Professor Fred Watson: It is, yeah. A very headache, yeah.
• 16:33
  Andrew Dunkley: Um, we gave uh, Jonti a lot of headaches
• 16:35
  while he was.
• 16:36
  Professor Fred Watson: Oh, good. Well that's good. He
• 16:38
  complained his keep then every time.
• 16:40
  Andrew Dunkley: He was constantly having
• 16:43
  headaches. Um. All right, uh, so we
• 16:46
  covered Jacob's question effectively.
• 16:48
  Professor Fred Watson: I, uh, hope so. Um, it's uh, really all I've
• 16:51
  got to say about it. Unless you want to throw
• 16:53
  in a couple of.
• 16:54
  Andrew Dunkley: Oh no, you're getting into the realm
• 16:57
  of science fiction if you ask me to start
• 16:59
  talking about this.
• 17:01
  Professor Fred Watson: That's all right. That's perfectly
• 17:02
  acceptable.
• 17:04
  Andrew Dunkley: Thanks, Jacob. Great. Uh, question.
• 17:08
  Okay, we checked all four systems,
• 17:11
  space nets, and our final question
• 17:14
  today comes from Ash in
• 17:17
  Brisbane.
• 17:17
  Jonti: G'day Fred and Andrew. Ash from Brisbane
• 17:20
  here. Um, got a bit of a mind bender
• 17:23
  question for you. I'm, uh, just wondering if
• 17:26
  we were to take one of the breakthrough star
• 17:28
  shot micro spacecraft that we're going to
• 17:31
  send through to Alpha Centauri, but launch it
• 17:34
  90 degrees to the plane of our galaxy,
• 17:37
  how far, ah, and for how long? Going to have
• 17:39
  to travel before I can look back and see what
• 17:41
  our galaxy looks like from the outside.
• 17:44
  Interested to hear your thoughts. See you
• 17:46
  guys. Love the show. Bye.
• 17:48
  Andrew Dunkley: Thank you, Ash. I'm, uh, thinking that
• 17:50
  question came from one of the
• 17:54
  hypotheticals, um, that were thrown at us
• 17:56
  recently, asking if we could go
• 17:59
  anywhere in the universe and look
• 18:02
  at something, what would it be? And your
• 18:04
  answer was to go outside our galaxy and look
• 18:06
  back at it and see what it really looked
• 18:08
  like.
• 18:09
  Professor Fred Watson: Yeah, that's right.
• 18:10
  Andrew Dunkley: I think that's where that one's come from.
• 18:13
  Professor Fred Watson: Yeah.
• 18:13
  Andrew Dunkley: So if Starshot was able to do that, uh, how
• 18:16
  long would it take to get out there
• 18:19
  far enough for us to be able to look back and
• 18:22
  go, oh, look, there's our, oh gosh, we need
• 18:24
  to take the garbage out. Um.
• 18:28
  Professor Fred Watson: Um, so, uh, the
• 18:31
  answer, rather remarkably, Andrew,
• 18:33
  is a number that you quoted in our last
• 18:36
  400,000 years. That's right.
• 18:41
  So I'm doing that as a calculation in my
• 18:43
  head. So Starshot is
• 18:46
  the, it's breakthrough. Starshot is
• 18:49
  still just a concept investigator, uh,
• 18:52
  that the idea with the project Breakthrough
• 18:55
  Starshot was to look at the possibilities of
• 18:57
  accelerating a spacecraft smaller than your
• 19:00
  mobile phone, uh, to something like a
• 19:03
  quarter of the speed of light so that you get
• 19:06
  to Alpha Centauri maybe
• 19:09
  in, um, rather than in, you know,
• 19:12
  4.3 years. Um, you get there in 16
• 19:14
  years or something like that. 4.3 years is
• 19:17
  how long it would take for light to get to
• 19:19
  us. Uh, you could do it in 16 years if
• 19:22
  you were traveling at four times a, uh,
• 19:24
  quarter of the speed of light. With
• 19:26
  conventional rockets it takes about 60,000
• 19:29
  years. So that's the difference. So if you.
• 19:31
  All right, so you accelerate your spacecraft
• 19:34
  to a quarter of the speed of light, I reckon
• 19:36
  you need to be 100,000 light years above the
• 19:38
  plane to see our galaxy in all its splendor.
• 19:41
  Because that's its diameter. It's 100,000
• 19:44
  light years in diameter. So you
• 19:47
  push back, um, push
• 19:49
  out one, uh, hundred thousand light years,
• 19:52
  you'll see the whole thing, um, at, uh, a
• 19:55
  quarter of the speed of light, that's going
• 19:56
  to take you 400,000 years. So it's not as
• 19:59
  quick trip.
• 20:00
  Andrew Dunkley: No, no. And, um, yeah, it makes
• 20:03
  it very hard to um, to arrange really,
• 20:05
  because by the time it's there, no one
• 20:08
  will have remembered it, why it was.
• 20:11
  Professor Fred Watson: Sent, what it was.
• 20:12
  Andrew Dunkley: And then of course it sends back the photo.
• 20:15
  It's 800 years. 800,000 years.
• 20:18
  Professor Fred Watson: Yeah, that's right. No, um, actually it's
• 20:20
  not. It's
• 20:22
  500,000 because, because the light travels
• 20:25
  back at, you know, speed of light.
• 20:27
  Andrew Dunkley: Speed of light, of course.
• 20:28
  Professor Fred Watson: Half a million. Half a million years for the
• 20:30
  full mission.
• 20:31
  Andrew Dunkley: Yeah.
• 20:31
  Professor Fred Watson: That's doable, I think, Andrew, don't you?
• 20:33
  Andrew Dunkley: Oh, you know, I,
• 20:36
  I'm, I'm a fairly patient person. I'm just
• 20:38
  sure I'm patient. That, patient enough for
• 20:41
  that?
• 20:42
  Professor Fred Watson: No, me neither.
• 20:43
  Andrew Dunkley: Do you think Starshot will happen though?
• 20:45
  Professor Fred Watson: No, I think, I think
• 20:48
  the results that are coming out are
• 20:50
  promising. But uh, the Starshot is
• 20:53
  only a project to investigate whether it's
• 20:56
  feasible. Uh, so that will wind up.
• 20:59
  Then somebody's got to put the money in to
• 21:02
  not just build the spacecraft, which is
• 21:04
  probably quite cheap because it's small,
• 21:07
  uh, but to arrange for that Mylar, uh, light
• 21:10
  sail that's going to catch the light of the
• 21:12
  laser. And the big ticket item is the
• 21:15
  laser itself. Yeah, we currently
• 21:18
  don't have a laser that's anywhere near
• 21:19
  powerful enough to uh, accelerate something
• 21:22
  to the quarter of the speed of light.
• 21:24
  Andrew Dunkley: Which leads me to um, uh, um,
• 21:28
  a question without notice because we've
• 21:29
  actually, I think in recent weeks or months
• 21:32
  had two or three questions directly
• 21:35
  related to sending a
• 21:38
  mission to Alpha Centauri using
• 21:40
  Laser United
• 21:42
  spacecraft. Um, this is not
• 21:45
  science fiction. This is feasible
• 21:49
  and doable. We've uh, been doing all sorts of
• 21:52
  experiments with spacecraft sending up
• 21:55
  wooden satellites and things like that.
• 21:58
  But this would probably be
• 22:00
  one of the most efficient ways to send a long
• 22:03
  haul spacecraft to another place.
• 22:06
  Professor Fred Watson: Yeah, so you're quite right. It is doable,
• 22:08
  it's feasible.
• 22:09
  Andrew Dunkley: Yeah.
• 22:10
  Professor Fred Watson: Uh, but you need the technology which we
• 22:11
  don't have at the moment. And um, uh, I
• 22:14
  mean we should put a footnote in that.
• 22:17
  It has been done. There's light sail
• 22:20
  experiments have already been done, uh, in
• 22:22
  orbit around the Earth just by the spacecraft
• 22:25
  deploying a very large sheet of Mylar,
• 22:28
  uh, and the ground controllers
• 22:31
  noticing the change in the acceleration of
• 22:33
  the spacecraft as a result of that. That's,
• 22:36
  that's been done and I think you and I
• 22:38
  covered it actually on one of the shows. Um,
• 22:41
  so the principle works. Uh,
• 22:43
  light sail, that's a principle that
• 22:46
  will actually work well. But uh,
• 22:50
  for the kind of figures that you were talking
• 22:53
  about sending a spacecraft to Alpha Centauri.
• 22:56
  You need such a big laser, uh, that
• 22:58
  we simply don't have at the moment. And it
• 23:01
  may even. You might even have to uh,
• 23:04
  put it into orbit around the Earth, uh
• 23:06
  because if you had it on the ground it might
• 23:08
  fry the atmosphere or something like that.
• 23:10
  Andrew Dunkley: Oh, that'd be fun.
• 23:11
  Professor Fred Watson: Yeah, yeah, we do.
• 23:13
  Andrew Dunkley: Yeah, we really need that.
• 23:15
  Um, yeah, I love that it's
• 23:18
  feasible. I have a
• 23:22
  sneaking suspicion that we could never do it
• 23:24
  out of Australia because of electricity
• 23:26
  prices and you're talking about leaving a
• 23:27
  light on for 16 years. I mean let's face it.
• 23:30
  Professor Fred Watson: Yes, and it's a big light too.
• 23:31
  Andrew Dunkley: Not feasible in Australia.
• 23:35
  Not with what we pay for.
• 23:36
  Professor Fred Watson: You get a bill.
• 23:38
  Andrew Dunkley: Um, another thing that uh, has fascinated me
• 23:41
  in recent times, uh, and I read a couple of
• 23:43
  stories like this when you were away, Fred
• 23:46
  was uh, the ongoing
• 23:49
  development into new engine technology
• 23:52
  for space travel. And I know NASA's been
• 23:55
  working on something called the Deep Space
• 23:57
  Engine. Um,
• 24:00
  um, it's a thruster,
• 24:02
  uh, that uh, is showing a heck of a lot of
• 24:05
  promise in terms of its power.
• 24:08
  Uh, it's a low cost chemical compound
• 24:10
  engine. Uh, it's lightweight,
• 24:13
  uh, and it promises to do some pretty amazing
• 24:16
  things if they can perfect it. We're on the
• 24:18
  cusp of probably achieving
• 24:21
  breakthrough technology in terms
• 24:24
  of speed and long haul space travel by
• 24:27
  the sound of it.
• 24:28
  Professor Fred Watson: Yeah, I think we covered um,
• 24:31
  some stories last year about EU
• 24:33
  ion drives and plasma drives and things like
• 24:36
  that which are all very promising.
• 24:38
  Andrew Dunkley: Yeah, I, yeah, I think it's uh, it's a pretty
• 24:40
  exciting time and uh, there's a lot of
• 24:43
  development going on, a lot of money being
• 24:44
  poured into it because there are rewards
• 24:47
  to be gained if you can get out there.
• 24:50
  Professor Fred Watson: Yeah. Ah.
• 24:50
  Andrew Dunkley: And um, you probably don't like the idea
• 24:53
  but they're. You know, we've already spoken
• 24:56
  about uh, in the last episode or two about
• 24:59
  uh, asteroid mining. That's a, um, that's
• 25:02
  a mission test that's been um. Well as
• 25:04
  we talked about in the previous episode, has
• 25:08
  fallen uh, foul unfortunately. But that,
• 25:10
  that's just the beginning. That's just going
• 25:12
  to be. Yes, it will continue on and of course
• 25:14
  mining the moon for that um, that, that
• 25:17
  mineral that's not so common on Earth. Can't
• 25:19
  remember the name of it.
• 25:20
  Professor Fred Watson: Something called water, I think.
• 25:22
  Andrew Dunkley: No, no, there's something else up there.
• 25:24
  Something else up there that they.
• 25:25
  Professor Fred Watson: Well, helium 3 is it?
• 25:27
  Andrew Dunkley: That's it. So there's a lot going on
• 25:30
  and um, yeah, I'm sorry to
• 25:33
  say that profit's uh, probably the driving
• 25:36
  force behind.
• 25:37
  Professor Fred Watson: It in the end. That's right.
• 25:39
  Andrew Dunkley: It's a very human thing to do.
• 25:41
  Yep, essentially.
• 25:44
  All right, thank you, Ash. Thanks, uh, for
• 25:46
  the question. Great to hear from you. And
• 25:48
  don't forget, if you've got questions for us,
• 25:50
  you're always welcome to send them to us via
• 25:53
  our website, spacenutspodcast.com
• 25:56
  or spacenuts IO
• 25:58
  and you just click on the little thing at the
• 26:01
  top called ama. Now, I know some time ago
• 26:03
  someone said, can you change it to something
• 26:05
  else so that we know where to send
• 26:07
  questions? Still working on that.
• 26:10
  Not sure where that's up to. I'll have to
• 26:12
  check with Huw in the studio, uh, as to where
• 26:15
  that's up to. But, uh, yeah, the AMA M button
• 26:17
  @ the top is the one you click on. When you
• 26:19
  click on that, which I'm doing right now, you
• 26:22
  can send us a text question just, um, with
• 26:24
  your name, email address and the message, or
• 26:26
  you can click start recording. If you've got
• 26:29
  a device with a microphone.
• 26:32
  It's really quite simple. And while you're on
• 26:34
  the website, um, just randomly click on, oh,
• 26:37
  I don't know, shop.
• 26:40
  Speaking about profitable humans. And, uh,
• 26:43
  look at all the, uh, Space Nuts
• 26:45
  paraphernalia. You can get stickers, you can
• 26:47
  get T shirts, you can get mugs, you can get,
• 26:50
  uh, polo shirts, dad hats, bucket
• 26:53
  hats. Uh, for those of you that live in those
• 26:55
  northern cold latitudes, um, you can get a
• 26:58
  ribbed beanie, all with the
• 27:01
  Space Nuts logo. You can even get Space Nuts
• 27:04
  socks.
• 27:05
  Professor Fred Watson: I need one of those beanies for the next time
• 27:07
  we go up to the Arctic.
• 27:08
  Andrew Dunkley: Yes, yes. Well, when
• 27:11
  we're up above the Arctic later this year,
• 27:13
  even though it'll be summer, the temperatures
• 27:15
  that we don't get down to here in winter,
• 27:17
  essentially. So we've bought ear muffs.
• 27:19
  So we should get some Space Nuts earmuffs, I
• 27:22
  reckon. Uh, there's also the, uh, the Space
• 27:25
  Nuts hoodie. That's a fun item
• 27:28
  if, you know, if you want to scare people.
• 27:30
  Not just Space Nut, but you've got a Space
• 27:32
  Nut hoodie on that'll freak people
• 27:34
  out. Yeah, that's all
• 27:37
  on the Space Nuts website and plenty of other
• 27:40
  things to see and do there. And if you want
• 27:41
  to become a Space Nut supporter, you can do
• 27:44
  that on the Space, uh, Nuts website
• 27:47
  as well. And thank you to all of our patrons.
• 27:50
  Uh, um, we think you are awesome. Um,
• 27:52
  thanks for getting behind us.
• 27:55
  Uh, and did I say goodbye, Fred?
• 27:58
  Professor Fred Watson: Uh, I'm not sure whether you got there or
• 28:00
  not, actually.
• 28:00
  Andrew Dunkley: Thank you, Fred.
• 28:01
  Professor Fred Watson: Nice.
• 28:04
  Good to talk to you, Andrew. And we shall
• 28:06
  speak again soon.
• 28:07
  Andrew Dunkley: We will indeed. And, uh, that's Professor
• 28:09
  Fred Watson, astronomer at large. And thanks
• 28:11
  to Huw in the studio, who couldn't be with us
• 28:13
  today because, uh, he actually thought
• 28:16
  Starshot was real. And, um, he went, bought a
• 28:18
  ticket, and it cost him a million
• 28:21
  bucks. So he's out, uh, doing his second
• 28:24
  and third job to pay it off from me, Andrew
• 28:26
  Dunkley. Thanks for your company. Catch you
• 28:27
  on the next episode of Space Nuts. Until
• 28:29
  then, bye bye.
• 28:31
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• 28:45
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