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Gravitational Waves, Cosmic What-Ifs & Dark Energy Dilemmas | Space Nuts: Astronomy Insights &... · Space News Today

• 0:00
  While the world takes a little bit of a
• 0:01
  rest over the Christmas New Year period,
• 0:03
  we thought we would, too. But we're not
• 0:05
  going to leave you hanging. We've dug
• 0:07
  into the archives and found a few of the
• 0:10
  biggest episodes of recent times. So,
• 0:13
  sit back and enjoy those. And we'll be
• 0:15
  back with new episodes of Space Nuts
• 0:18
  probably in the middle of January. See
• 0:20
  you then. Space Nuts. Hi there. Thanks
• 0:22
  for joining us. This is Space Nuts Q&A.
• 0:25
  My name is Andrew Dunley, your host. And
• 0:28
  coming up on this episode, we got a
• 0:30
  question about gravitational waves and
• 0:32
  the big bang. We're also going to uh
• 0:34
  look at a what if question. Love the
• 0:36
  what if questions. Uh which is asking
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  about the life of Earth. Not life on
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  Earth, the life of Earth if the sun
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  never died. Interesting uh angle. And
• 0:49
  we're also going to look at uh time and
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  dark energy. That's all coming up on the
• 0:55
  Q&A edition of Space Nuts.
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  >> 15 seconds. Guidance is internal. 10 9
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  Ignition sequence start.
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  >> Space Nuts.
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  >> 5 4 3 2
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  >> 1 2 3 4 5 5 4 3 2 1
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  >> Space Nuts.
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  >> Astronauts report. It feels good.
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  >> And joining me once again is Professor
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  Fred Watson, astronomer at large. Hello
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  Fred.
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  >> Hi Andrew. How are you doing?
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  >> I'm doing as much as I can.
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  >> Good. Good. Good, good to be Q&A with
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  you.
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  >> Yes, you too. Um, shall we get stuck
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  straight in?
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  >> Why not? Yes, why not?
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  >> All right. Uh, our first question comes
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  I'm not sure if it's Bo or Boa. I'll
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  have to listen more carefully. Here we
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  go.
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  >> Hello, Fred and Andrew. Is Bo here from
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  Melbourne? I hope you're well. I have a
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  question for you, and it is not about
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  dark energy, nor it is about dark
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  matter, but it is about gravitational
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  waves. It's a straightforward question.
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  Did the big bang produce gravitational
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  waves? As we understand it,
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  gravitational waves are generated when
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  two massive bodies such as neutron stars
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  and black holes collided each other and
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  cause that ripple in the fabric of
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  spacetime.
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  But when the universe as just began uh
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  in infinite density and so forth when it
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  came into existence via the big bang did
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  it produce gravitational waves or echoes
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  and can we detect those echoes in space
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  and time very much like the cosmic
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  microwave background radiation that we
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  see today. Anyway, I hope that makes
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  sense. I'd love to hear your answer.
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  Thank you very much.
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  >> Thank you Boa. Um that's a good
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  question. I you know we talk about the
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  big bang a lot. We get a lot of
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  questions about it. Uh and I mean it was
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  a a massive event. We don't know why. We
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  don't know a lot but uh we know we can
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  see that it happened through the cosmic
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  microwave background radiation that's
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  still evident today. But gravitational
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  waves would I mean if the universe
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  didn't exist at the moment of the big
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  bang and was being created as a
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  consequence of that
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  I'm not sure gravitational waves could
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  have happened the way we understand them
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  with other events in our universe. So um
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  yeah I'm not sure about this one. So um
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  the the thing is Andrew um the yes the
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  universe was created in that instant uh
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  of the big bang um and so you're right
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  um you know in the conventional theory
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  standard Einsteinian physics we we
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  imagine that time and space didn't exist
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  before the big bang so uh you've got to
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  create some space for your gravitational
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  waves to go through uh which is kind of
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  thinking yeah and so um And so yes,
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  there was the instant of the big bang
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  that created this singularity in time
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  and space followed by this period was it
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  10us 33 of a second something like that
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  in duration uh which we call the period
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  of inflation when the when the expansion
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  really took hold uh and it you know the
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  universe went from the size of a
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  football to the size of a galaxy in
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  something like 10 theus 33 a second and
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  uh the thinking is and I'm actually
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  dragging this up from reading a few
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  years ago but but that yes that per that
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  inflationary period as we call it would
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  have created gravitational waves.
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  >> Uhhuh. Uh or maybe a gravitational wave
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  but
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  >> I was about to say
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  >> maybe just one big one
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  >> that's right
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  >> at that point. But the the issue is um
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  that uh it is a gravitational wave of
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  very very very low frequency.
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  So um the gravitational waves that we
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  get from colliding neutron stars for
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  example uh they produce waves which are
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  basically have a frequency which is in
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  the audio range which is why we can you
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  know turn those uh gravitational wave
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  signals into an audio signal very easily
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  after you've amplified it up a bit and
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  after LIGO has done its magic on it and
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  that's where we get this chirp signal as
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  as two neutron stars or whatever merge
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  together uh and and eventually that
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  because they're spinning ever ever ever
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  more rapidly uh and so the frequency
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  goes up of the waves that are being
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  emitted and and then stop uh at a high
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  point because that's where they've co
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  coalesed into a single object. Um now
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  you can think of those
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  uh audio frequencies. Uh you know we
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  might talk about something like 500 htz
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  as an audio frequency or you could take
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  440 htz as u the frequency of of um the
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  standard a note in the in the musical
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  spectrum. Um so if let's stick with 500
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  because that's an easy one. Uh so the
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  the the period of time between one peak
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  of the of the wave and the next uh is
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  1/500th of a second. And so if you think
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  that's the inter interval of time of a
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  characteristic gravitational wave from
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  uh two colliding objects. Now the issue
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  as I understand it is that the interval
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  between peaks in a gravitational wave uh
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  produced by inflation
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  is about the same as the age of the
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  universe now. It's not uh 1/500th of a
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  second. It's you know several several
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  billion years u perhaps even tens of
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  billions of years. It's quite a while
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  since I read up on this. So, so normal
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  gravitational wave technology is simply
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  not equipped to detect these low
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  frequency
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  ultra ultra low frequency gravitational
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  waves, but there might be other ways of
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  seeing them. Uh, and one of the things
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  people have looked for, uh, and I'm not
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  really very well up on this, but there
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  is a potential
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  signal in the cosmic microwave
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  background radiation that the flash of
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  the Big Bang that we see that that gives
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  us what the universe looked like 380,000
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  years after the Big Bang. That's that's
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  what we're seeing there. that um that
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  radiation uh contains information not
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  just on its brightness but also on its
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  polarization
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  uh you know that radiation is polarized
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  a bit like light can be polarized and
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  I'm not really drawing the drawing the
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  links very strongly here but I
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  understand that there are links between
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  very low frequency gravitational waves
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  and that polarization signal so it's one
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  of the things that people are looking
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  for to try and detect this this
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  polarization uh within the cosmic
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  microwave background radiation. So it's
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  not at all a dough question uh but it's
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  quite a complex answer.
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  >> Yeah. Yeah. But the the big bang itself
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  could have initially been one you know
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  created one gravitational wave.
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  >> Yes. That's right. Yeah. That's more or
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  less it.
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  >> Yeah.
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  >> There you go. Um you're right on the
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  money. It's just a matter of finding a
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  way of seeing them. Would they Is it
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  possible these gravitational waves still
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  bouncing around like the cosmic
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  microwave background radiation?
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  >> Well, yes. Yes. But um at such a low
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  frequency that you don't actually know
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  it's there. You've got to find other
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  you've got to find other ways of
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  detecting it because there's got not
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  going to be any change in the
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  gravitational wave signal over, you
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  know, a human experimental lifetime. If
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  you've got a frequency whose time
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  interval is measured in billions of
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  years, forget it.
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  >> Yeah, that's a tough one.
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  >> Forget it.
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  >> Thanks, Boa. That's a great question and
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  thanks for sending it in. Uh, we've got
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  a question from one of our regulars,
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  Renie, uh, who is from sunny West Hills,
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  California. Uh, this is a what if
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  question. And theoretically, if the sun
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  were never to die, let's assume it's
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  just never going to die, would the Earth
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  eventually erode, decay,
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  and die on its own?
• 9:28
  >> Um, yeah. Um, it's
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  >> Well, my answer is no, because we'll
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  destroy it first. It it could be very
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  different. I mean what so if what Ren is
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  saying is that yes the sun we know it's
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  going to evolve over the next few
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  billion years uh and it will change and
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  that will eventually result in the earth
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  being swamped by the outer atmosphere of
• 9:47
  the sun which might not be very nice for
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  anybody left on earth. Uh but uh if that
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  didn't happen, if the sun just um you
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  know went on its merry way being a
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  normal star,
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  the there will be a few things that will
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  happen over that time scale which
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  wouldn't which wouldn't which we know
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  won't happen because the sun's going the
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  sun turning into a red giant's going to
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  overtake it. One of them is uh the um
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  tidal breaking of the earth's rotation
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  so that it always uh faces the moon. So
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  the earth's day will change from uh 24
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  hours to something like if I remember
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  rightly it's 42 days that it's it's
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  about that length of time.
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  >> Uh and that's it turning once and the
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  moon will go around the sky around the
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  earth in the same time. So the earth and
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  the moon will constantly face one
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  another with a a month and a day which
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  are both equivalent to I think it's
• 10:46
  about 42 43 days something like that. Uh
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  so that's that's going to change things
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  quite a bit. Um so that would you know
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  certainly alter the the um atmospheric
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  dynamics of the earth if one side's
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  getting warmed up for 40 of 20 days
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  rather than just one day uh of day and
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  night. So a lot of things change um and
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  yeah the constant bombardment by the
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  magnetic particles from the sun uh I
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  don't know to what extent the earth's
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  magnetic field might erode but there
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  will certainly be be changes may even be
• 11:21
  >> what about go ahead go on sorry
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  >> no I was just going to say if humans
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  were still around in that period uh
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  would we well okay no let me rephrase
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  would we adapt as these things changed
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  and reached that point, would we be able
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  to adapt as a species and other life on
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  Earth adapt to live in that kind of
• 11:42
  environment?
• 11:43
  >> Well, it certainly is these changes are
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  ones that take place very slowly indeed.
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  Uh and and over kind of longer periods
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  than the characteristic evolution time
• 11:53
  to get from, you know, one mutation to
• 11:56
  another, whatever that might be for
• 11:57
  humans. Um, so yeah, they're they're
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  slow and uh I'm sure humans could adapt
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  to them. Uh, we're a pretty adaptive
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  species. We might also by then be
• 12:08
  capable of building the mega structures
• 12:10
  that might protect us from some of the
• 12:12
  sun's funny things going on. Uh, it's
• 12:16
  hard to know really, isn't it? But but I
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  I think generally speaking, I mean,
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  Reny's question is a good one. Um, what
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  happens if uh if nothing happens to the
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  sun? Uh, does the earth just sort of
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  survive? It probably survives. It will
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  be changed. We might find we're all
• 12:31
  living in plastic domes or something by
• 12:33
  then rather than, you know, because the
• 12:36
  atmosphere has been so messed about
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  with. But yes. Yes. I think I think I
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  I'm I'm an optimist that humankind would
• 12:43
  survive.
• 12:44
  >> Yeah. Um now it's interesting because um
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  I mean we we know what's going to
• 12:50
  happen. We kind of know when it's going
• 12:51
  to happen, but I if it didn't, it would
• 12:54
  create a whole array of new challenges
• 12:56
  for humanity because we would have to
• 12:59
  learn to live in a very
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  somewhat hostile environment, I imagine,
• 13:05
  because um the the planet would not be
• 13:07
  the same. And I can't imagine what it
• 13:09
  would be like to have a 42 long
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  >> 42 day long day.
• 13:14
  >> Um
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  >> well, you know, birthdays would be few
• 13:17
  and far between, wouldn't they? uh they
• 13:19
  would, but you you know we're gonna
• 13:20
  we're going to know what that's like
• 13:22
  very soon because the the day on the
• 13:24
  moon is 20, you know, uh 29 days
• 13:27
  effectively from one
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  >> full moon to another. So yeah, so we've
• 13:31
  we've we've already got something like
• 13:33
  that uh in store for people to
• 13:36
  experience. It'll be very interesting to
• 13:37
  see what even the Arteimus astronauts on
• 13:40
  the moon make of all that.
• 13:43
  >> Yeah. Yeah. Very interesting, Renie.
• 13:45
  That's a great question. Thanks for
• 13:46
  sending it in. Much appreciated. And
• 13:49
  next up, we've uh got Daniel. Uh this is
• 13:53
  um
• 13:55
  a sort of dark energy question. Sort of.
• 13:59
  Hey guys, Daniel from Adelaide here.
• 14:01
  There seems to be more and more
• 14:02
  discoveries lately in the very early
• 14:04
  universe that shouldn't be possible
• 14:05
  because not enough time has passed like
• 14:07
  size of galaxies or black holes. I've
• 14:10
  got a far out theory I'd love to share.
• 14:11
  What if time and dark energy were
• 14:14
  actually the same thing? So we know for
• 14:16
  about the second half of the universe
• 14:17
  that dark energy has been accelerating
• 14:19
  its expansion. Could this therefore mean
• 14:21
  that there was less dark energy in the
• 14:23
  first half? And if that's the case, what
• 14:25
  if time actually went slower in the
• 14:27
  early universe? So from our perspective,
• 14:29
  what took a really short amount of time
• 14:31
  actually happened in normal time with
• 14:33
  normal being in quotes. I'd previously
• 14:35
  asked a question on the show whether
• 14:36
  dark energy is related to black holes. I
• 14:39
  think there was a paper around the time
• 14:40
  that that kind of suggested that it was
• 14:42
  and we know that black holes do distort
• 14:44
  time. So, if time is part of the fabric
• 14:46
  of space,
• 14:48
  maybe dark energy is too, but it's
• 14:50
  actually one of the same thing. I'm
• 14:52
  expecting a very quick simple no, but I
• 14:55
  wanted to ask anyway.
• 14:57
  >> All right. Thanks, Daniel. Uh, yeah. Is
• 15:00
  um time and dark energy, are they the
• 15:03
  same thing?
• 15:04
  >> You never get a quick and simple no from
• 15:06
  me, Daniel. It's always a long drawn out
• 15:09
  complex no.
• 15:12
  not always but I think in this case yeah
• 15:15
  your your thinking is interesting uh
• 15:17
  we've we've talked recently as well
• 15:19
  about the um the fact that um
• 15:24
  this new controversial theory from Joe
• 15:26
  Silk at all uh over in Baltimore
• 15:29
  suggesting that perhaps black holes
• 15:31
  super massive black holes came first
• 15:33
  they were formed in the early universe
• 15:35
  and that goes a long way to explaining
• 15:37
  uh the conundrum that you mentioned at
• 15:39
  the start of your question there that a
• 15:40
  lot seems to have happened in the first
• 15:42
  uh in the first uh few millions or
• 15:46
  hundreds of millions of years of the
• 15:48
  universe's existence. Um so we we kind
• 15:52
  of understand the grav the gravitational
• 15:55
  time dilation uh effects pretty well and
• 15:58
  they're actually quite small uh from our
• 16:01
  vantage point here 38 13.8 billion years
• 16:05
  later. Um, and we and but you're right
• 16:09
  to make the point that uh dark energy uh
• 16:12
  only seems to have appeared over the
• 16:15
  second half of the age of the universe,
• 16:17
  but that's more likely to be uh it's
• 16:21
  because it its measurable effect has
• 16:24
  only become apparent. We think that
• 16:26
  during the first half of the universe's
• 16:28
  age, um there was the galaxies within
• 16:32
  the universe were close enough to each
• 16:34
  other that gravitational attraction
• 16:36
  would have basically kept the expansion
• 16:39
  due to dark energy in check, the
• 16:41
  accelerated expansion uh due to dark
• 16:44
  energy. Uh and so it's only when you get
• 16:47
  past a kind of tipping point where
• 16:49
  suddenly the the mass of galaxies in the
• 16:52
  universe is not enough not strong enough
• 16:54
  gravitationally to break the
• 16:57
  acceleration of the expansion. By that I
• 16:59
  mean B R A K rather than B R E A K. Uh
• 17:03
  it's not enough to slow it down. And so
• 17:05
  the acceleration takes over. Uh and
• 17:09
  that's why it's a tricky thing just to
• 17:11
  try and tease out and we've talked about
• 17:14
  this recently as well whether the dark
• 17:17
  energy is a constant whether it's
• 17:19
  something that's uh a factor that hasn't
• 17:22
  changed in terms of its uh its release
• 17:25
  as space as space expands. Um it's
• 17:29
  because there is this added impact of
• 17:31
  the gravitational pull of the galaxies
• 17:34
  uh stopping us from basically seeing the
• 17:37
  effect of dark energy the accelerated
• 17:39
  expansion of the universe back in the
• 17:41
  early universe. So I think all those
• 17:42
  things are are well and truly understood
• 17:45
  and kept fairly separate by the by the
• 17:48
  scientists looking at them. And by that
• 17:50
  I mean time and and dark energy. So
• 17:52
  that's a long complicated no.
• 17:55
  >> Yeah. Yeah. Um, okay. Daniel Winfred
• 17:58
  says, "I think these things have been
• 18:00
  long understood." That's that's his way
• 18:02
  of saying you're way off way way off the
• 18:05
  mark.
• 18:10
  >> But it's worth asking because otherwise,
• 18:12
  you know, obviously this is something
• 18:14
  people are thinking about. So, it's
• 18:15
  worth asking these um these
• 18:18
  >> different questions to um just, you
• 18:21
  know, see see if it's a possibility.
• 18:24
  >> Thanks, Daniel. Appreciate that.
• 18:26
  >> Great question.
• 18:27
  >> Uh, if you've got questions for us,
• 18:29
  please send them in because we could
• 18:30
  always use them. Uh, just, uh, go to our
• 18:33
  website, spacenutspodcast.com,
• 18:35
  spacenuts.io,
• 18:36
  and click on the various links. The AMA
• 18:38
  link will give you, uh, access to, uh,
• 18:42
  text and voice uh, audio. Or you can
• 18:45
  click on the little, it's not purple,
• 18:47
  it's green. When did they change the
• 18:48
  color of that? Uh, send us your Oh, no.
• 18:51
  It's It's purple when you hover on it.
• 18:52
  There you go. Uh send us your questions
• 18:55
  uh on the right hand side of our
• 18:56
  homepage and uh don't forget to tell us
• 18:59
  who you are and where you're from. Fred,
• 19:01
  we're done again. Thank you so much.
• 19:02
  >> Uh always a pleasure, Andrew. And I hope
• 19:05
  we'll stick it again very very soon.
• 19:07
  It's a distinct possibility. Could be
• 19:10
  with could be within 13.8 billion years
• 19:13
  in fact.
• 19:14
  >> Yes. Thanks uh Fred. See you soon. Fred
• 19:16
  Watson, astronomer at large. And uh
• 19:19
  thanks to Hugh in the studio for making
• 19:20
  our lives so much more difficult with
• 19:22
  these split episodes. But no, it's okay.
• 19:25
  Uh and from me, Andrew Dunley, thank you
• 19:27
  so much for joining us. Uh looking
• 19:28
  forward to your company on the next
• 19:29
  episode of Space Nuts. See you then.
• 19:33
  >> Space Nuts.
• 19:34
  >> You'll be listening to the Space Nuts
• 19:36
  podcast
• 19:38
  >> available at Apple Podcasts, Spotify,
• 19:41
  iHeart Radio, or your favorite podcast
• 19:44
  player. You can also stream on demand at
• 19:46
  byes.com. This has been another quality
• 19:49
  podcast production from sites.com.