Space Nuts Episode #478 Q&A
Join Andrew Dunkley and Professor Fred Watson in this engaging Q&A edition of Space Nuts as they tackle intriguing questions from listeners worldwide. From the massive size of Jupiter to the nature of gravity and the mysteries of the universe's accelerating expansion, this episode is packed with cosmic conundrums and insightful discussions.
Episode Highlights:
- Jupiter's Massive Growth: Dive into the fascinating story of why Jupiter grew to such a colossal size compared to other planets. Explore the role of gas accretion, planetesimals, and the runaway growth effect in shaping the largest planet in our solar system.
- The Nature of Gravity : Examine the intriguing question of whether gravity is finite or infinite. Discover the complexities of gravitational waves, the stiffness of Space, and how these concepts influence our understanding of gravity's reach.
- The Night Sky in Earth's Early Era : Imagine standing on Earth when it first formed and ponder what the night sky would have looked like. Understand how the universe's expansion and the redshift of the Big Bang's light affect our cosmic view.
- The Fate of Comets : Consider the life cycle of comets and whether they can lose enough material to become nothing. Learn about the trails of dust left behind and their connection to meteor showers.
- Solar Panels at Night: Explore the possibility of generating solar power at night using light from stars and the moon. Delve into the limitations of current technology and the potential for future innovations.
- The Universe's Accelerating Expansion: Discuss the acceleration of the universe's expansion and whether it is constant or variable. Contemplate the implications for our understanding of dark energy and the structure of the universe.
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Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.
00:00 - This is a Q and A episode where we let the audience set the agenda
01:19 - Why did Jupiter grow to such a massive size compared to other planets
07:30 - Dean in Queensland has a question about whether gravity is infinite or finite
12:00 - Dean: We really don't understand gravity. Well, it'll be when quantum gravity really comes of age
13:50 - Professor Fred Watson answers a few quick fire questions via text message
14:22 - Given the night sky seems fairly full of stars to the naked eye today
18:26 - Could you develop solar panels that work at night by collecting energy from other stars
20:04 - Daniel asks whether the rate of acceleration is constant or ever so slightly variable
25:49 - The Space Nuts podcast group Facebook page has thousands of members
✍️ Episode References
Scientific American article on Jupiter's growth
https://www.scientificamerican.com/article/why-was-jupiters-rapid-growth-spurt-delayed-for-millions-of-years/
Nature Astronomy journal
https://www.nature.com/natastron/
Become a supporter of this podcast: https://www.spreaker.com/podcast/space-nuts--2631155/support (https://www.spreaker.com/podcast/space-nuts--2631155/support?utm_source=rss&utm_medium=rss&utm_campaign=rss) .
Episode link: https://play.headliner.app/episode/24641700?utm_source=youtube
00:00:00 --> 00:00:03 Hi there space nuts again Andrew Dunley
00:00:03 --> 00:00:06 here this is a Q&A episode where we let
00:00:06 --> 00:00:08 the audience set the agenda and today
00:00:08 --> 00:00:10 we'll be answering questions about the
00:00:10 --> 00:00:14 size of Jupiter that's a why question uh
00:00:14 --> 00:00:17 another maybe whatif question or why
00:00:17 --> 00:00:22 question is uh gravity finite uh and
00:00:22 --> 00:00:25 what would the night sky have been like
00:00:25 --> 00:00:27 uh if you're standing on the surfaces of
00:00:27 --> 00:00:30 Earth in its very early era
00:00:30 --> 00:00:33 uh plus uh the demise of comets uh can
00:00:33 --> 00:00:35 we generate solar power at night and the
00:00:35 --> 00:00:37 acceleration of the universe all our
00:00:37 --> 00:00:39 questions will be answered on this
00:00:39 --> 00:00:43 episode of Space Nuts 15 seconds
00:00:43 --> 00:00:47 guidance is internal 10 9 ignition
00:00:47 --> 00:00:52 sequence start Space Nuts 5 4 3 2 1 2 3
00:00:52 --> 00:00:57 4 5 5 4 3 Space Nuts astronauts reported
00:00:57 --> 00:01:00 feels good and you just can't get enough
00:01:00 --> 00:01:02 of audience questions it is Professor
00:01:02 --> 00:01:04 Fred what's an astronomer at large hello
00:01:04 --> 00:01:07 Fred uh hello Andrew yes uh I do enjoy
00:01:07 --> 00:01:10 the audience questions because it tells
00:01:10 --> 00:01:13 tells me we've got an audience which
00:01:13 --> 00:01:16 is uh and and we get a lot of questions
00:01:16 --> 00:01:20 uh in audio and text format and uh we
00:01:20 --> 00:01:22 might as well go straight to our first
00:01:22 --> 00:01:27 one and this one comes from uh David
00:01:27 --> 00:01:29 yeah Dave in inverell in Northern New
00:01:29 --> 00:01:32 South Wales Burell the uh the um gem
00:01:32 --> 00:01:35 capital of New South Wales I would I
00:01:35 --> 00:01:36 would suggest a lot of people go up
00:01:36 --> 00:01:39 there fossicking for gems uh and Dave
00:01:39 --> 00:01:41 thanks for your kind words um of course
00:01:41 --> 00:01:43 in a recent episode I went public about
00:01:43 --> 00:01:46 my um fight with prostate cancer and
00:01:46 --> 00:01:48 Dave has been dealing with his own
00:01:48 --> 00:01:53 issues but um Dave I appreciate your uh
00:01:53 --> 00:01:55 your thoughts thank you so much uh Dave
00:01:55 --> 00:01:58 asks uh good day Andrew and Fred just a
00:01:58 --> 00:02:00 quick question for Fred because I
00:02:00 --> 00:02:01 wouldn't know the answer is that what
00:02:01 --> 00:02:05 you're saying Dave uh why I don't why
00:02:05 --> 00:02:08 did Jupiter grow to such a massive size
00:02:08 --> 00:02:10 compared to other planets was there
00:02:10 --> 00:02:12 simply just more gas and material
00:02:12 --> 00:02:14 available in that part of the solar disc
00:02:14 --> 00:02:17 where it Formed jeee Dave you might have
00:02:17 --> 00:02:19 answered it straight up or is there
00:02:19 --> 00:02:21 something else in play here for it's an
00:02:21 --> 00:02:24 interesting story and I'm grateful to
00:02:24 --> 00:02:25 Dave for sending me down the rabbit hole
00:02:25 --> 00:02:27 of Jupiter's
00:02:27 --> 00:02:31 formation uh to see what the story is um
00:02:31 --> 00:02:32 I mean it's part what Dave says is
00:02:32 --> 00:02:36 partly the case Uh there's Big reservoir
00:02:36 --> 00:02:39 of gas uh and and dust I mean it was the
00:02:39 --> 00:02:41 we think it was the dusty material that
00:02:41 --> 00:02:43 formed the core and then the gas was
00:02:43 --> 00:02:47 collected uh once that was in place but
00:02:47 --> 00:02:49 um there are some subtleties here and
00:02:49 --> 00:02:51 I'm going to point our Dave in
00:02:51 --> 00:02:55 particular um to a very nice uh article
00:02:55 --> 00:02:59 it's six years old now uh 2018 uh on the
00:02:59 --> 00:03:02 scientific ific American website really
00:03:02 --> 00:03:05 excellent website with um you know very
00:03:05 --> 00:03:08 high degree of accuracy uh uh but it's
00:03:08 --> 00:03:10 called why was Jupiter's rapid growth
00:03:10 --> 00:03:14 spur delayed for millions of years um
00:03:14 --> 00:03:18 and it's basically uh saying that it
00:03:18 --> 00:03:23 wasn't just a continuous growing process
00:03:23 --> 00:03:26 that Jupiter underwent but it it
00:03:26 --> 00:03:30 actually uh was was delaying
00:03:30 --> 00:03:33 uh and and the mechanism for that delay
00:03:33 --> 00:03:36 is quite interesting so uh this is um
00:03:36 --> 00:03:38 basically research that came from from
00:03:38 --> 00:03:40 Swiss
00:03:40 --> 00:03:44 Switzerland um so we we we believe that
00:03:44 --> 00:03:47 uh the planet ismal these sort of
00:03:47 --> 00:03:50 kilometer sized
00:03:50 --> 00:03:54 asteroids uh are what basically was the
00:03:54 --> 00:03:55 raw material of the planets and the
00:03:56 --> 00:03:58 planet ismal in turn had grown from dust
00:03:58 --> 00:04:00 sticking together partly
00:04:00 --> 00:04:01 electrostatically in the beginning but
00:04:01 --> 00:04:03 eventually by gravity and they formed
00:04:03 --> 00:04:04 their own you know their own gravity
00:04:05 --> 00:04:07 pulls in more stuff so you've got uh
00:04:07 --> 00:04:12 these planet ismal um and the uh the
00:04:12 --> 00:04:13 thinking is that during the first two
00:04:13 --> 00:04:15 million years of Jupiter's
00:04:16 --> 00:04:18 formation uh it was in the right place
00:04:18 --> 00:04:21 for a lot of these things to smash into
00:04:21 --> 00:04:26 the Proto Jupiter uh and that made it
00:04:26 --> 00:04:30 hot a lot of energy caused by Collision
00:04:30 --> 00:04:34 and what that does is uh stops the
00:04:34 --> 00:04:37 process of gas secreting in other words
00:04:37 --> 00:04:39 you know the gas molecules that are out
00:04:39 --> 00:04:42 and about in space which are eventually
00:04:42 --> 00:04:44 going to form part of Jupiter's very
00:04:44 --> 00:04:45 thick atmosphere that make it the big
00:04:45 --> 00:04:48 world that it is um they the these
00:04:48 --> 00:04:51 authors are suggesting that uh the
00:04:51 --> 00:04:53 bombardment by
00:04:53 --> 00:04:56 planimal gave so much heat energy that
00:04:56 --> 00:05:00 the gas did not want to collect it it
00:05:00 --> 00:05:03 didn't accreate and so the planet grew
00:05:03 --> 00:05:06 more slowly than it had been uh and then
00:05:06 --> 00:05:13 it says you know the theory says that uh
00:05:13 --> 00:05:17 basically uh the first few million years
00:05:17 --> 00:05:19 uh within the first few million years it
00:05:19 --> 00:05:22 was 20 times the mass of Earth uh but
00:05:22 --> 00:05:23 then the
00:05:23 --> 00:05:27 larger plantis ismal were bombarding it
00:05:27 --> 00:05:30 uh and they as I've just said crashed
00:05:30 --> 00:05:34 to Jupiter uh releasing energy stopping
00:05:34 --> 00:05:39 the collection of gas um and so it it
00:05:39 --> 00:05:41 growth rate they now think had slowed
00:05:41 --> 00:05:43 down so that by three million years of
00:05:43 --> 00:05:46 age um it was only 50 times the mass of
00:05:46 --> 00:05:49 the Earth uh which means that uh it took
00:05:49 --> 00:05:52 two million years to grow 30 times the
00:05:52 --> 00:05:55 mass of the Earth but then sort of
00:05:55 --> 00:05:58 something happened uh and it's a process
00:05:58 --> 00:06:01 that the Au of this article is calling
00:06:01 --> 00:06:04 runaway gas accretion uh where the gas
00:06:04 --> 00:06:06 actually collects and then that makes it
00:06:06 --> 00:06:07 more massive and then more G gas
00:06:07 --> 00:06:10 collects and it's more massive uh and so
00:06:10 --> 00:06:13 it grew to its current uh roughly 300
00:06:13 --> 00:06:14 times the mass of the earth size that it
00:06:14 --> 00:06:18 is now so this is like like a like a
00:06:18 --> 00:06:20 snowball rolling down a hill type yeah
00:06:20 --> 00:06:23 that's a very nice an analog yeah that's
00:06:23 --> 00:06:25 right it's you know you can't stop it
00:06:25 --> 00:06:27 it's going down the hill it's going to
00:06:27 --> 00:06:29 it's going to collect more and more snow
00:06:29 --> 00:06:32 h um interesting
00:06:32 --> 00:06:35 so and they and you know they think that
00:06:35 --> 00:06:38 once Jupiter uh started to become
00:06:38 --> 00:06:40 dominant then it was a runaway effect
00:06:40 --> 00:06:42 because the bigger it is the more stuff
00:06:42 --> 00:06:46 it pulls in uh and uh basically grows to
00:06:46 --> 00:06:49 to its present size it's an article that
00:06:49 --> 00:06:52 it's got a lot of complexity in it um
00:06:52 --> 00:06:56 but uh is one that's worth reading Dave
00:06:56 --> 00:06:58 if you're interested in why Jupiter got
00:06:58 --> 00:07:00 to be the size it is
00:07:00 --> 00:07:02 actually the original paper was produced
00:07:02 --> 00:07:04 was published in nature astronomy but
00:07:04 --> 00:07:06 there's a nice Scientific American
00:07:06 --> 00:07:08 article as I mentioned why was Jupiter's
00:07:08 --> 00:07:10 rapid growth spurt delayed for millions
00:07:10 --> 00:07:10 of
00:07:10 --> 00:07:13 years there you are Dave um there is a
00:07:13 --> 00:07:15 good reason for it right place at the
00:07:15 --> 00:07:18 right time although it took a long time
00:07:18 --> 00:07:21 yeah came in fits and
00:07:21 --> 00:07:23 starts all right thanks Dave great to
00:07:23 --> 00:07:25 hear from
00:07:25 --> 00:07:28 you okay we checked all four systems and
00:07:28 --> 00:07:32 It Go space nuts our next question comes
00:07:32 --> 00:07:35 from Dean in redcliffe and I wonder if
00:07:35 --> 00:07:39 Dean is a dolphins fan the Dolphins
00:07:39 --> 00:07:41 football team based in Red Cliff in
00:07:41 --> 00:07:43 Queensland and they've just lost their
00:07:43 --> 00:07:46 coach to a team in Sydney the South
00:07:46 --> 00:07:47 Sydney rabbit
00:07:47 --> 00:07:49 o and guess what the national rugby
00:07:49 --> 00:07:51 league's done as the first game of next
00:07:51 --> 00:07:54 year the Dolphins versus the rabbito so
00:07:54 --> 00:07:57 I'm wondering how Dean will feel about
00:07:57 --> 00:08:00 that if he's a a dolphins fan now let's
00:08:00 --> 00:08:03 hear um Dean's question hi fron Andrew
00:08:03 --> 00:08:06 this is Dean in redcliff in Queensland
00:08:06 --> 00:08:07 I'm a retired architect and I've been a
00:08:07 --> 00:08:10 Space Nuts listener for a long time
00:08:10 --> 00:08:12 finally I have got around to sending in
00:08:12 --> 00:08:14 a question I had always understood that
00:08:15 --> 00:08:16 the effect of gravity was infinite
00:08:16 --> 00:08:19 although negligible at Great distances
00:08:19 --> 00:08:21 however I recently heard that it may be
00:08:21 --> 00:08:24 finite this seems like a reasonable idea
00:08:24 --> 00:08:26 when I think about ocean waves here on
00:08:26 --> 00:08:29 Earth ocean waves will disect to zero
00:08:29 --> 00:08:31 over enough distance if the wind stops
00:08:31 --> 00:08:34 pushing them ripples from a pebble
00:08:34 --> 00:08:36 dropped in a Still Pond will also
00:08:36 --> 00:08:38 dissipate to zero this may be due to
00:08:38 --> 00:08:40 surface tension and friction between
00:08:40 --> 00:08:42 water molecules which is an inherent
00:08:42 --> 00:08:44 quality of the medium conducting the
00:08:44 --> 00:08:48 waves now to my question SpaceTime is
00:08:48 --> 00:08:50 the medium that gravity distorts could
00:08:50 --> 00:08:53 it be that the stiffness of SpaceTime
00:08:53 --> 00:08:55 eventually overcomes the diminishing
00:08:55 --> 00:08:58 gravity of a distant massive object so
00:08:58 --> 00:09:00 that its gravitational effect become
00:09:00 --> 00:09:02 zero rather than just
00:09:02 --> 00:09:04 negligible to on the right track with
00:09:04 --> 00:09:07 the particles and dark matter within
00:09:07 --> 00:09:09 space contribute to its stiffness and to
00:09:09 --> 00:09:12 the dissipation of gravity waves thanks
00:09:12 --> 00:09:14 for the podcast look forward to hearing
00:09:14 --> 00:09:15 your
00:09:15 --> 00:09:18 answer thank you Dean great question
00:09:18 --> 00:09:19 really good
00:09:19 --> 00:09:22 question it
00:09:22 --> 00:09:26 is um and yeah I guess the answer is
00:09:26 --> 00:09:29 maybe I mean um Dean's right uh we've
00:09:30 --> 00:09:31 talked about the stiffness of space
00:09:31 --> 00:09:34 actually in one of the um we talked
00:09:34 --> 00:09:35 about it in one of the Fred's flippant
00:09:35 --> 00:09:40 facts didn't we uh uh I said space is
00:09:40 --> 00:09:43 flexible but not very uh it it's Young's
00:09:43 --> 00:09:45 modulus which is the measure of
00:09:45 --> 00:09:47 stiffness which Dean would definitely be
00:09:47 --> 00:09:49 familiar with as an architect uh the
00:09:49 --> 00:09:52 youngest modulus of space is 100 billion
00:09:52 --> 00:09:55 billion times that of Steel so it's very
00:09:55 --> 00:10:00 stiff indeed um but um I'm not sure that
00:10:00 --> 00:10:02 that
00:10:02 --> 00:10:07 stiffness uh would contribute to a um an
00:10:07 --> 00:10:10 attenuation of the
00:10:10 --> 00:10:12 gravitational force we kind of talking
00:10:12 --> 00:10:15 about two things gravity
00:10:15 --> 00:10:20 itself uh is the the Distortion of space
00:10:20 --> 00:10:22 gravitational waves which we know travel
00:10:22 --> 00:10:26 at the speed of light um are uh
00:10:26 --> 00:10:29 basically vibrations in space and you
00:10:29 --> 00:10:31 can imagine that gravitational waves
00:10:32 --> 00:10:35 would be attenuated to Zero by the
00:10:35 --> 00:10:37 stiffness of space because of that
00:10:37 --> 00:10:41 Young's modulus but gravity itself uh is
00:10:41 --> 00:10:44 a is a an inverse Square law uh which
00:10:44 --> 00:10:49 says that it's infinite um if you if you
00:10:49 --> 00:10:51 sort of have a look online to see what
00:10:51 --> 00:10:53 people think about gravity being whether
00:10:53 --> 00:10:55 it's infinite or not uh there's some
00:10:55 --> 00:11:00 quite interesting uh aspects come out um
00:11:00 --> 00:11:03 one is that uh well gravitational waves
00:11:03 --> 00:11:06 aren't infinite because uh eventually
00:11:06 --> 00:11:09 they would reach the cosmic Horizon the
00:11:09 --> 00:11:11 microwave background radiation which is
00:11:11 --> 00:11:14 moving away at the speed of light uh and
00:11:14 --> 00:11:17 these things would um you know the
00:11:17 --> 00:11:20 basically um the gravitational waves
00:11:20 --> 00:11:23 themselves would interact with that and
00:11:23 --> 00:11:25 and maybe cancel out I'm not quite sure
00:11:25 --> 00:11:26 I didn't really follow the logic of that
00:11:26 --> 00:11:29 one uh and some someone else um
00:11:29 --> 00:11:34 thought that because uh the plank length
00:11:34 --> 00:11:36 is
00:11:36 --> 00:11:42 um the length uh in matter below which
00:11:42 --> 00:11:45 the laws of physics don't apply uh the
00:11:45 --> 00:11:47 plank length would be something that
00:11:47 --> 00:11:51 would stop uh gravitational waves being
00:11:51 --> 00:11:52 infinite we're talking about
00:11:52 --> 00:11:55 gravitational waves now not gravity uh
00:11:55 --> 00:11:57 because eventually get vibrations that
00:11:57 --> 00:11:58 were less than the plank leg that was
00:11:58 --> 00:12:00 that was the point about that so a lot
00:12:01 --> 00:12:03 of stuff that seems to me to be going
00:12:03 --> 00:12:08 around in circles um but my um my take
00:12:08 --> 00:12:11 on it is still that as an inverse Square
00:12:11 --> 00:12:16 law gravity gravitation uh Excuse excuse
00:12:16 --> 00:12:18 me reaches an infinite distance it's
00:12:18 --> 00:12:21 effectively zero it it ASM totically
00:12:21 --> 00:12:23 approaches zero that means it it gets
00:12:23 --> 00:12:24 nearer and nearer to being
00:12:25 --> 00:12:29 zero no fun formly never reaches it but
00:12:29 --> 00:12:33 it is yes it's an infinite Force so uh I
00:12:33 --> 00:12:34 don't know that dark energy and dark
00:12:34 --> 00:12:36 matter thrown into that mix really add
00:12:36 --> 00:12:38 anything to it it's a great question Li
00:12:38 --> 00:12:40 it's made me think about these things
00:12:40 --> 00:12:43 sorry Andrew go ahead so are we saying
00:12:43 --> 00:12:45 are we saying that
00:12:45 --> 00:12:48 um they they phase out they just sort of
00:12:48 --> 00:12:51 fizzle well maybe maybe gravitational
00:12:51 --> 00:12:53 waves do and it might be because of that
00:12:53 --> 00:12:57 stiffness um but gravity itself doesn't
00:12:57 --> 00:12:59 that's okay until runs into something
00:13:00 --> 00:13:00 else
00:13:00 --> 00:13:03 and also creating a gravity yeah they'll
00:13:03 --> 00:13:07 try it yes they meet and yeah and then
00:13:07 --> 00:13:08 did they just push against each other
00:13:08 --> 00:13:11 and create that gr Point as you know
00:13:11 --> 00:13:12 they can cancel out because exactly as
00:13:12 --> 00:13:15 you said that's how the Gran points work
00:13:15 --> 00:13:18 yes yeah it's really interesting and and
00:13:18 --> 00:13:21 and adds more to the empty vessel that
00:13:21 --> 00:13:23 is our knowledge of
00:13:23 --> 00:13:27 gravity it is really don't understand
00:13:27 --> 00:13:29 gravity yeah we just know it's there
00:13:30 --> 00:13:33 it's uh it's one of those um I I suppose
00:13:33 --> 00:13:35 if someone ever figures it out that's a
00:13:35 --> 00:13:37 Nobel Prize waiting to happen isn't it
00:13:37 --> 00:13:40 definitely well it'll be um when quantum
00:13:40 --> 00:13:42 gravity really comes of age when we
00:13:42 --> 00:13:43 really understand quantum gravity which
00:13:43 --> 00:13:45 we don't at the moment so yeah that will
00:13:45 --> 00:13:49 be it right thank you Dean and all the
00:13:49 --> 00:13:51 best thanks for your question this is
00:13:51 --> 00:13:53 Space Nuts Andrew Dunley here with
00:13:53 --> 00:13:56 Professor fa
00:13:56 --> 00:14:00 Watson 3 2
00:14:00 --> 00:14:04 Space Nuts we've got another text
00:14:04 --> 00:14:06 question Fred and this one comes from
00:14:06 --> 00:14:08 Daniel who is in
00:14:08 --> 00:14:11 Adelaide and he said I've saved up a few
00:14:11 --> 00:14:13 quickfire questions I'm hoping you could
00:14:13 --> 00:14:16 answer please uh yes we'd be happy to do
00:14:16 --> 00:14:19 so uh so um we we'll knock them all off
00:14:19 --> 00:14:21 one at a time uh quick fire means you
00:14:21 --> 00:14:22 don't have to spend too much time on
00:14:22 --> 00:14:25 them Fred uh we know the universe's
00:14:25 --> 00:14:27 expansion has been accelerating for
00:14:27 --> 00:14:30 about the last five billion years uh
00:14:30 --> 00:14:31 given the night sky seems fairely Full
00:14:32 --> 00:14:34 of Stars to the naked eye today what
00:14:34 --> 00:14:36 would it have looked like if you were
00:14:36 --> 00:14:38 standing on earth when it Formed would
00:14:38 --> 00:14:41 the night sky have been as bright as day
00:14:41 --> 00:14:44 for example that's his first question
00:14:44 --> 00:14:48 yeah the answer is no so our vantage
00:14:48 --> 00:14:50 point you know 4.6 billion years ago
00:14:51 --> 00:14:53 when the Earth was forming um would be
00:14:53 --> 00:14:56 similar to what it is today yes galaxies
00:14:56 --> 00:14:59 are closer together and they might be uh
00:15:00 --> 00:15:03 you know a little bit brighter um than
00:15:03 --> 00:15:05 we see them now but I think it would
00:15:05 --> 00:15:08 still be a similar sky that we'd see
00:15:08 --> 00:15:11 you've got to go back a lot further uh
00:15:11 --> 00:15:14 in time to be able to see a night sky as
00:15:14 --> 00:15:17 bright as day and what that is is still
00:15:17 --> 00:15:18 being able to see the flash of the Big
00:15:18 --> 00:15:21 Bang um at the moment that flash of the
00:15:21 --> 00:15:22 Big Bang has been red shifted into
00:15:22 --> 00:15:24 microwaves which is why we don't see a
00:15:24 --> 00:15:28 brilliant sky but we would um if our
00:15:28 --> 00:15:30 eyes were sensitive to microwaves or if
00:15:30 --> 00:15:33 we were looking at the early Universe um
00:15:33 --> 00:15:34 you know not long after it became
00:15:34 --> 00:15:37 transparent then we'd see a very bright
00:15:37 --> 00:15:40 sky that just totally unrelated question
00:15:40 --> 00:15:42 but that just prompted in my mind a
00:15:42 --> 00:15:44 thought about uh animals and insects
00:15:44 --> 00:15:47 would they see the night sky completely
00:15:47 --> 00:15:50 differently to us that's what um some of
00:15:50 --> 00:15:52 mani's work is about she works on that
00:15:52 --> 00:15:53 sort of thing from the point of view of
00:15:53 --> 00:15:56 light pollution yes they do uh they're
00:15:56 --> 00:15:58 sensitive many of them are sensitive to
00:15:58 --> 00:16:01 different way bounds than what we are uh
00:16:01 --> 00:16:03 and in fact some in insects need the
00:16:03 --> 00:16:06 night sky dong Beatles um work by
00:16:06 --> 00:16:08 aligning their direction of travel with
00:16:08 --> 00:16:11 the Milky Way um so you know it's quite
00:16:11 --> 00:16:16 an extraordinary yeah they do check it
00:16:16 --> 00:16:19 out yep wow so so many one liners I
00:16:19 --> 00:16:25 can't use now
00:16:25 --> 00:16:28 rats oh that's fascinating it's totally
00:16:28 --> 00:16:30 off the track track in terms of uh the
00:16:30 --> 00:16:34 question but um yeah amazing uh so
00:16:34 --> 00:16:36 that's your first answer Daniel your
00:16:36 --> 00:16:39 second question uh when a comet passes a
00:16:39 --> 00:16:41 star it gets its dust and Ice blown off
00:16:41 --> 00:16:43 but will that Comet ever lose enough
00:16:43 --> 00:16:46 material to become nothing or does it
00:16:46 --> 00:16:50 add material back in a uh trans uh back
00:16:50 --> 00:16:54 as it traverses space um well some of
00:16:54 --> 00:16:56 them actually just end up crashing into
00:16:56 --> 00:16:58 planets and and the sun itself with
00:16:58 --> 00:17:00 which means they're adding to those
00:17:00 --> 00:17:03 things somewhat but uh yeah can they
00:17:03 --> 00:17:05 just be sort of as I've used this word
00:17:05 --> 00:17:08 before fizzled out over
00:17:08 --> 00:17:11 time yeah they can um and we what you
00:17:11 --> 00:17:14 would be left with is a basically a tra
00:17:14 --> 00:17:18 you know a trail of dust uh which is
00:17:18 --> 00:17:21 what we pass through when we see meteor
00:17:21 --> 00:17:23 streams uh so there probably are comets
00:17:23 --> 00:17:25 that have eventually dissipated I'm not
00:17:25 --> 00:17:27 sure that any that have
00:17:27 --> 00:17:31 been seen by humans and recognized as
00:17:31 --> 00:17:33 comets I'm not sure that any of those
00:17:33 --> 00:17:35 have dissipated to to being just Trails
00:17:35 --> 00:17:38 of dust but that's the end Pro process
00:17:38 --> 00:17:39 uh and because you know comets are made
00:17:40 --> 00:17:41 of dust which is sort of bonded together
00:17:41 --> 00:17:44 by ice and the ice sublimes it goes
00:17:44 --> 00:17:46 straight into a gas and gets blown away
00:17:46 --> 00:17:48 and some of the Dust is released and
00:17:48 --> 00:17:50 eventually you're going to wind up just
00:17:50 --> 00:17:53 with a a little pile of dust that will
00:17:53 --> 00:17:55 spread itself along the path of the
00:17:55 --> 00:17:56 Comets
00:17:56 --> 00:17:58 forward yeah and and the Earth passes
00:17:58 --> 00:18:00 through through these dust trails from
00:18:00 --> 00:18:03 time to time when we see those um uh
00:18:03 --> 00:18:05 meteorites that um appear in the night
00:18:05 --> 00:18:08 sky at certain times of the year meteors
00:18:08 --> 00:18:11 they're only meteors land meteorites
00:18:11 --> 00:18:12 when they hit the ground yeah yeah
00:18:12 --> 00:18:14 that's right so we see that we see that
00:18:14 --> 00:18:17 it's all right it's part of my job uh
00:18:17 --> 00:18:20 they they um yeah they uh that's exactly
00:18:20 --> 00:18:21 right we see the meteor showers which
00:18:22 --> 00:18:23 are because we're passing through the
00:18:23 --> 00:18:28 dust trail from a comet H and uh the
00:18:28 --> 00:18:31 last question question uh from Daniel is
00:18:31 --> 00:18:33 could you develop solar panels that work
00:18:33 --> 00:18:36 at Night by collecting energy from other
00:18:36 --> 00:18:39 stars and or the reflected light from
00:18:39 --> 00:18:39 the
00:18:39 --> 00:18:42 Moon yeah the amount of light we get
00:18:42 --> 00:18:44 from stars and the Moon is very small
00:18:44 --> 00:18:47 compared with sunlight um and I mean we
00:18:47 --> 00:18:50 do know we can create electricity from
00:18:50 --> 00:18:52 all of those objects and we do it as
00:18:52 --> 00:18:54 soon as we take a photograph of of the
00:18:54 --> 00:18:57 stars or the moon with a digital camera
00:18:57 --> 00:18:59 uh because that's you know the uh the
00:18:59 --> 00:19:03 sensors in your phone or your camera um
00:19:03 --> 00:19:06 are generating electricity which you can
00:19:06 --> 00:19:09 then measure and detect but it's not
00:19:09 --> 00:19:12 really useful amounts and I think
00:19:12 --> 00:19:15 probably the physics of you know silicon
00:19:15 --> 00:19:17 uh which is one of the materials that
00:19:17 --> 00:19:19 does this will probably limit how much
00:19:19 --> 00:19:22 electricity you could collect uh you
00:19:22 --> 00:19:24 probably have fairly low efficiency so I
00:19:24 --> 00:19:26 suspect lunar panels are something that
00:19:26 --> 00:19:28 we're not going to see much of in the
00:19:28 --> 00:19:30 near future they might be developed in
00:19:30 --> 00:19:33 naturally yeah yes I I certainly know
00:19:33 --> 00:19:36 that my solar panels um don't show a
00:19:37 --> 00:19:40 scar of um electricity generation at at
00:19:40 --> 00:19:42 night when we've got a big bright full
00:19:42 --> 00:19:45 moon cuz I've looked yeah so
00:19:45 --> 00:19:48 technology yeah um technology is beyond
00:19:49 --> 00:19:50 us at the moment but I will check again
00:19:50 --> 00:19:52 next time we've got a big moon because
00:19:52 --> 00:19:55 um um
00:19:55 --> 00:19:57 yes I'm not in the same house now I've
00:19:57 --> 00:19:59 got a different array so
00:19:59 --> 00:20:01 maybe maybe it's improved technology but
00:20:01 --> 00:20:03 I I doubt I really doubt it would do
00:20:03 --> 00:20:06 anything uh thank you Daniel I think
00:20:06 --> 00:20:08 that's all of your questions done and
00:20:08 --> 00:20:10 our final question today comes from
00:20:10 --> 00:20:13 Chris who is in Tasmania hi Fred and
00:20:13 --> 00:20:15 Andrew this is Chris here from the human
00:20:15 --> 00:20:18 Valley in Tasmania um my question is
00:20:18 --> 00:20:19 that we know that the expansion of the
00:20:19 --> 00:20:21 universe is accelerating but I was
00:20:21 --> 00:20:23 wondering if we're able to detect
00:20:23 --> 00:20:25 whether the rate of acceleration is
00:20:25 --> 00:20:27 constant or ever so slightly variable
00:20:27 --> 00:20:29 and whe that might provide a clue as the
00:20:29 --> 00:20:31 structure of what the universe is
00:20:31 --> 00:20:34 expanding in as in the expansion hitting
00:20:34 --> 00:20:36 regions of different density of who
00:20:36 --> 00:20:38 knows what causing the acceleration to
00:20:38 --> 00:20:41 temporarily slow or speeder that's my
00:20:41 --> 00:20:43 question thanks for the show really
00:20:43 --> 00:20:46 enjoy it thanks Chris uh the huan valley
00:20:46 --> 00:20:50 is a glorious part of the world if you
00:20:50 --> 00:20:52 like cold weather but I know it's um
00:20:52 --> 00:20:54 yeah Taz taz's wonderful I got some
00:20:54 --> 00:20:55 friends down there visiting at the
00:20:55 --> 00:20:57 moment and I'm checking out all their
00:20:57 --> 00:21:00 photos on um on Facebook uh Judy and I
00:21:00 --> 00:21:03 actually honeymooned in
00:21:03 --> 00:21:07 Tasmania uh what 30 38 nearly 38 years
00:21:08 --> 00:21:09 ago oh my
00:21:09 --> 00:21:12 gosh H or no it wouldn't be that long
00:21:12 --> 00:21:15 hang on how old car no we 38 years ago
00:21:15 --> 00:21:18 30 30 37 years ago I don't know I can't
00:21:18 --> 00:21:19 add it up
00:21:19 --> 00:21:24 7 35 years ago there you go I fin Judy
00:21:24 --> 00:21:27 what's he talking about Judy she yeah
00:21:27 --> 00:21:29 she she just her eyes whenever I try to
00:21:29 --> 00:21:31 figure these things
00:21:31 --> 00:21:34 out um so yeah uh acceleration of the
00:21:34 --> 00:21:36 universe speeding up slowing down
00:21:36 --> 00:21:38 stopping being
00:21:38 --> 00:21:40 interrupted what's the story and we
00:21:41 --> 00:21:42 can't see that though can we we can't
00:21:42 --> 00:21:45 see beyond a certain limit when we
00:21:45 --> 00:21:47 observe the universe uh we talk about
00:21:47 --> 00:21:48 the observable
00:21:48 --> 00:21:51 universe um and then there's the
00:21:51 --> 00:21:52 universe beyond that because we just
00:21:52 --> 00:21:56 can't see it so we really don't know
00:21:56 --> 00:21:58 what's going on out there do we no
00:21:58 --> 00:22:00 that's right um the bit that we can't
00:22:00 --> 00:22:02 see we don't we guess it's more or less
00:22:02 --> 00:22:05 the same as it is here but uh but look
00:22:05 --> 00:22:07 um this question and it's a great one
00:22:07 --> 00:22:10 from Chris is right at the Forefront of
00:22:10 --> 00:22:14 of cosmology um has the accelerated
00:22:14 --> 00:22:17 expansion of the universe changed over
00:22:17 --> 00:22:22 time uh or is it constant and
00:22:23 --> 00:22:26 the the theory that's been uh most
00:22:26 --> 00:22:29 popular in the last 20 years um has been
00:22:29 --> 00:22:31 that it is constant in fact we've added
00:22:31 --> 00:22:33 what's called Einstein's cosmological
00:22:33 --> 00:22:35 constant to the equations that that
00:22:35 --> 00:22:39 describe that so what it's saying is the
00:22:39 --> 00:22:42 acceleration by by constant I mean let
00:22:42 --> 00:22:45 me let me change my wording slightly
00:22:45 --> 00:22:48 it's proportional to the volume of space
00:22:48 --> 00:22:50 so the more space you have the more
00:22:50 --> 00:22:52 acceleration you get the more Dark
00:22:52 --> 00:22:54 Energy you have and hence the more
00:22:54 --> 00:22:56 acceleration um
00:22:56 --> 00:23:00 now the I think the current thinking is
00:23:00 --> 00:23:03 that there may be a change it may not be
00:23:03 --> 00:23:05 something that's got this Co
00:23:05 --> 00:23:06 cosmological constant it might have
00:23:06 --> 00:23:11 varied over the age of the Universe um
00:23:11 --> 00:23:14 and that would perhaps help to
00:23:14 --> 00:23:16 illuminate what dark energy is because
00:23:16 --> 00:23:18 that's the the problem at the moment we
00:23:18 --> 00:23:19 have no idea what it is it just
00:23:19 --> 00:23:22 something that makes the universe expand
00:23:22 --> 00:23:25 more rapidly uh it is a springiness of
00:23:25 --> 00:23:27 space that's a nice way to put it
00:23:27 --> 00:23:30 probably uh but it's not uh so any
00:23:30 --> 00:23:34 change in the in the uh acceleration
00:23:34 --> 00:23:37 wouldn't necessarily in fact probably
00:23:37 --> 00:23:40 not at all as Chris has conjectured it
00:23:40 --> 00:23:42 wouldn't speak of the universe plowing
00:23:42 --> 00:23:45 into a an area of higher density because
00:23:45 --> 00:23:47 the it's the universe itself that we're
00:23:47 --> 00:23:48 talking about it's not anything that
00:23:48 --> 00:23:52 it's in it's just the universe uh the
00:23:52 --> 00:23:56 cont B in time yeah um but but yeah if
00:23:56 --> 00:23:58 it can be shown that it has varied and
00:23:58 --> 00:24:00 there observations going on as we speak
00:24:00 --> 00:24:02 to try and determine that um if it's can
00:24:02 --> 00:24:05 be sh that it's varied then uh yeah that
00:24:05 --> 00:24:08 might illuminate what dark energy is and
00:24:08 --> 00:24:09 give us some better idea because at the
00:24:09 --> 00:24:11 moment we haven't a clue and it's not
00:24:11 --> 00:24:15 just space has a clue nobody
00:24:15 --> 00:24:18 has That's The $64 Question isn't it
00:24:18 --> 00:24:21 really indeed it is yes y yeah that
00:24:21 --> 00:24:23 that's another Nobel Prize winner
00:24:23 --> 00:24:27 probably correct that one yeah so Chris
00:24:27 --> 00:24:29 you're you're asking Nobel winning
00:24:29 --> 00:24:32 questions exactly a lot of our listeners
00:24:32 --> 00:24:36 do which is great that shows uh we're we
00:24:36 --> 00:24:38 should be a Nobel prizewinning podcast
00:24:38 --> 00:24:42 really shouldn't we no well they they
00:24:42 --> 00:24:44 had the Australian podcast Awards the
00:24:44 --> 00:24:48 other day um we didn't get nominated
00:24:48 --> 00:24:51 because we didn't even know it
00:24:51 --> 00:24:55 existed sounds like SM just that yeah
00:24:55 --> 00:24:57 yeah we just carry on you know we just
00:24:57 --> 00:25:00 do our jobs you guys have all the prizes
00:25:00 --> 00:25:02 we'll just we'll just do our thing yeah
00:25:03 --> 00:25:06 take listeners with us yeah exactly
00:25:06 --> 00:25:09 right exactly right uh thank you Chris
00:25:09 --> 00:25:12 uh great question uh but uh you're
00:25:12 --> 00:25:14 pretty tricky one at this point in time
00:25:14 --> 00:25:16 uh maybe down the track when somebody's
00:25:16 --> 00:25:18 waving their prize in front of us in the
00:25:18 --> 00:25:20 form of a Nobel Prize we'll know the
00:25:20 --> 00:25:21 answer to that
00:25:21 --> 00:25:24 one and if you've got a question for us
00:25:24 --> 00:25:25 go to our website and click on that
00:25:25 --> 00:25:28 little uh Link at the top that's got am
00:25:28 --> 00:25:31 a and send us your text audio question
00:25:31 --> 00:25:34 that way we we'll do our level best to
00:25:34 --> 00:25:37 answer them for you and uh that's about
00:25:37 --> 00:25:39 it and I have a bit of a browser around
00:25:39 --> 00:25:41 the website don't forget to join our
00:25:41 --> 00:25:44 social media followers on the Space Nuts
00:25:44 --> 00:25:47 Facebook page Space Nuts on Instagram or
00:25:47 --> 00:25:49 the um or the supporters page the Space
00:25:49 --> 00:25:52 Nuts podcast group Facebook page that's
00:25:52 --> 00:25:54 where listeners get together and and
00:25:54 --> 00:25:56 chat and compare their astronomical
00:25:56 --> 00:25:58 pictures and they even tell a few
00:25:58 --> 00:25:59 terrible dad jokes I don't know where
00:25:59 --> 00:26:02 they got that idea from but um yeah it's
00:26:02 --> 00:26:04 it's a great little Community if you
00:26:04 --> 00:26:07 want to join um there's few thousand
00:26:07 --> 00:26:09 people involved in that now which is
00:26:09 --> 00:26:13 quite incredible uh and um that's about
00:26:13 --> 00:26:15 it uh thank you Fred uh we will catch
00:26:15 --> 00:26:18 you again real soon sounds good thank
00:26:18 --> 00:26:20 you Andre all right Professor Fred
00:26:20 --> 00:26:23 Watson uh astronomer at large and Hugh
00:26:24 --> 00:26:26 in the studio uh yeah couldn't be with
00:26:26 --> 00:26:29 us today due to Cosmo logical
00:26:29 --> 00:26:31 inconsistencies and from me from me
00:26:31 --> 00:26:33 Andrew lley thanks for your company
00:26:33 --> 00:26:34 we'll see you on the next episode of
00:26:35 --> 00:26:38 Space Nuts bye for now nuts you'll be
00:26:38 --> 00:26:41 listening to the Space Nuts
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