Dec. 16, 2024
Jupiter's Giant Leap, Gravity's Infinite Debate & Cosmic Queries: #478 Q&A
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...
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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.
For more Space Nuts, including our continually updating newsfeed and to listen to all our episodes, visit our website. Follow us on social media at SpaceNutsPod on facebook, X, YouTube, Tumblr, Instagram, and TikTok. We love engaging with our community, so be sure to drop us a message or comment on your favourite platform.
For more Space and Astronomy News Podcasts, visit our HQ at www.bitesz.com.
If you'd like to help support Space Nuts and join our growing family of insiders for commercial-free episodes and more, visit spacenutspodcast.com/about
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...
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.
For more Space Nuts, including our continually updating newsfeed and to listen to all our episodes, visit our website. Follow us on social media at SpaceNutsPod on facebook, X, YouTube, Tumblr, Instagram, and TikTok. We love engaging with our community, so be sure to drop us a message or comment on your favourite platform.
For more Space and Astronomy News Podcasts, visit our HQ at www.bitesz.com.
If you'd like to help support Space Nuts and join our growing family of insiders for commercial-free episodes and more, visit spacenutspodcast.com/about
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...
WEBVTT
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Hi, there, Space Nuts again Andrew Dunkley. Here, this is
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a Q and A episode where we let the audience
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set the agenda, and today we'll be answering questions about
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the size of Jupiter. That's a why question, another maybe
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what if question? Or why question? Is gravity finite? And
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what would the night sky have been like if you're
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standing on the surfaces of Earth in its very early era?
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Plus the demise of comets, can we generate solar power
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at night? And the acceleration of the universe. All our
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questions will be answered on this episode of Space Nuts.
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Fifteen second Channel ten nine ignition Space Nuts or three two.
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One Space Nuts as the Night Report. It Bil's good
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and you just can't get an enough of audience questions.
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It is Professor Fred, what's an astronomer at large? Hello Fred?
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Hello Andrew, Yes, sir, I do enjoy the audience questions
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because it tells me we've got an audience which is some.
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And we get a lot of questions in audio and
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text format and we might as well go straight to
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our first one. And this one comes from David Dave
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in Verrel in northern New South Wales in Burrell, the
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gem capital of New South Wales. I would I would
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suggest a lot of people go up there. FOSSi king
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for gems and Dave, thanks for your kind words. Of course,
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in a recent episode, I went public about my fight
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with prostate cancer, and Dave has been dealing with his
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own issues. But Dave, I appreciate your your thoughts. Thank
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you so much. Dave asks Gray, Andrew and Fred. Just
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a quick question for Fred, because I wouldn't know the answer.
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Is that what you're saying, Dave? Why? I don't why
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did Jupiter grow to such a massive size compared to
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other planets. Was there simply just more gas and material
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available in that part of the solid disc where it formed. Jeez, Dave,
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he might have answered it straight up, or is there
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something else in play here?
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For it's an interesting story, and I'm grateful today for
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sending me down the rabbit hole of Jupiter's formation to
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see what the story is. I mean, it's what Dave
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says is partly the case. There's a big reservoir of
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gas and dust. I mean, we think it was the
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dusty material that formed the core, and then the gas
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was collected once that was in place. But there's some
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subtleties here, and I'm going to point Dave in particular
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to a very nice article. It's six years old now
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twenty eighteen on the Scientific American website, really excellent website
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with you know, very high degree of accuracy. But it's
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called why was Jupiter's rapid growth delayed for millions of years?
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And it's basically saying that it wasn't just a continuous
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growing process that Jupiter underwent, but it actually was was delayed,
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and the mechanism for that delay is quite interesting. So
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this is basically research that came from from Swiss Switzerland.
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So we we believe that the planet is amals. These
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sort of kilometer sized asteroids are what basically was the
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raw material of the planets, and the planetimals in turn
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had grown from dust sticking together, part electrostatically in the beginning,
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but eventually by gravity and they formed their own you know,
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their own gravity pools in more stuff. So you've got
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these planetsimals, and the thinking is that during the first
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two million years of Jupiter's formation, it was in the
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right place for a lot of these things to smash
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into the proto Jupiter, and that made it hot. A
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lot of energy caused by collision, and what that does
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is stops the process of gas screting. In other words,
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you know the gas molecules that are out and about
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in space which are eventually going to form part of
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Jupiter's very thick atmosphere that make it the big world
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that it is. These authors are suggesting that the bombardment
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by planet simals gave so much heat energy that the
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gas did not want to collect it, it didn't accrete,
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and so the planet grew more slowly than it had been.
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And then it says, you know, the theory says that
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basically the first few million years, within the first few
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million years, it was twenty times the mass of Earth.
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But then the larger Planetisimals were bombarding it and they,
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as I've just said, crashed into to Jupiter, releasing energy,
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stopping the collection of gas, and so it's growth rate
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they now think had slowed down so that by three
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million years of age, it was only fifty times the
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mass of the Earth, which means that it took two
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million years to grow thirty times the mass of the Earth.
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But then sort of something happened, and it's a processed
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that the authors of this article is calling runaway gas
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secretion where the gas actually collects, and then that makes
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it more massive, and then more gas collects and it's
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more massive, and so it grew to its current roughly
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three hundred times the massive the Earth size that it
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is now.
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So this is like a like a like a snowball
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rolling down a hill.
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Yeah, that's a very nice and analog. Yeah, that's right.
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It's you know, you can't stop, it's going down the hill.
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It's gonna it's gonna collect more and more smooth hmm.
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Interesting.
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So the and they and you know, they think that
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once Jupiter started to become dominant, then it was a
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runaway effect because the bigger it is, the more stuff
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it pulls in, uh, and basically grows to its present size.
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It's an article that has got a lot of complexity
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in it, but is one that's worth reading, Dave, if
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you're interested in why Jupiter got to be the size
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it is. Actually, the original paper was produced was published
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in Nature Astronomy. But there's a nice scientific American article
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as I mentioned, why was Jupis's rapid growth spurt delayed
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for millions of years?
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There you are, Dave, there is a good reason for
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it right place at the right time, although it took
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a long time, it fits and starts all right. Thanks Dave.
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Great to hear from you.
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Okay, we take a.
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Space nuts and next question comes from Dean in Redcliffe
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and I wonder if Dean is a Dolphins fan. The
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Dolphins football team based in Redcliffe in Queensland, and they've
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just lost their coach to a team in Sydney, the
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South Sydney rabbit Os. And guess what the National Rugby
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League's done as the first game of next year the
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Dolphins versus the Rabbits. So I'm wondering how Dean will
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feel about that if he's a Dolphins fans. Here rahm
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Dean's question.
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Hi Fred and Andrew. This is Dean in Redcliffe in Queensland.
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I'm a retired architect and I've been a Space Nunts
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listener for a long time. Finally I have got around
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to send in in a question. I had always understood
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that the effect of gravity was infinite, although negligible at
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great distances. However, I recently heard that it may be finite.
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This seems like a reasonable idea when I think about
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ocean waves here on Earth. Ocean waves will dispact to
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zero over enough distance if the wind stops pushing them.
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Ripples from a pebble dropped in a still pond will
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also dissipate to zero. This may be due to surface
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tension and friction between water molecules, which is an inherent
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quality of the medium conducting the waves. Now of my question,
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space time is the medium that gravity distorts. Could it
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beat at the stiffness of space? Time eventually overcomes the
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diminishing gravity of a distant massive object so that its
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gravitational effect become zero rather than just negligible. T I'm
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on the right track with the particles and dark matter
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within space contribute to its stiffness and to the dissipation
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of gravity waves. Thanks for the podcast. Look forward to
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hearing your answer.
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M Thank you, Jan, great question, really good question.
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It is, And yeah, I guess the answer is maybe.
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I mean Dean's right. We've talked about the stiffness of space.
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Actually in one of the and we talked about taking
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one of the Fred's flippant facts, didn't we Yes, I
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said space is flexible, but not very It's Young's modulus,
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which is the measure of stiffness, which Dean would definitely
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be familiar with as an architect. The Young's modulus of
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space is one hundred billion billion times that of steel,
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so it's very stiff indeed, But I'm not sure that
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that stiffness would contribute to an attenuation of the gravitational force.
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We're kind of talking about two things. Gravity itself is
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the distortion of space. Gravitational waves, which we know travel
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at the speed of light, are basically vibrations in space,
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and you can imagine that gravitational waves would be attenuated
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to zero by the stiffness of space because of that
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Young's modulus. But gravity itself is an inverse square or
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which says that it's infinite. If you sort of have
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a look online to see what people think about gravity
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being whether it's infinite or not, there's some quite interesting.
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Aspects come out.
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One is that, well, gravitational waves aren't infinite because eventually
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they would reach the cosmic horizon, the microwave background radiation
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which is moving away at the speed of light, and
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these things would you know, they basically the gravitational waves
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themselves would interact with that and maybe cancel out. I'm
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not quite sure. I didn't really follow the logic of
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that one. And someone else. I thought that because the
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plank length is the length in matter below which the
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laws of physics don't apply, the plank length will be
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something that would stop gravitational waves being infinite. We're talking
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about gravitational waves, no, not gravity, because eventually you get
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vibrations that were less than the plank length. That was
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the point of that. So a lot of stuff that
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seems to me to be going around in circles. But
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my my take on it is still that there's an
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inverse squall or gravity. Gravitation Uh, excuse me, excuse me.
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Reach is an infinite distance. It's effectively zero. It a
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symptotically approaches zero. That means it gets nearer and nearer
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to being zero. No fundation formally never reaches it, but
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it is. Yes, it's an infinite force. So I don't
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know that dark energy and dark matter thrown into that
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makes really add anything to it. It's a great question, lie,
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and it's maybe thick about these things. Sorry, Andrew, go ahead.
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So are we saying are we saying that they phase it,
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they just sort of fizzle.
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Well, maybe maybe gravitational waves do, and it might be
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because of that stiffness. But gravity itself doesn't.
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That's okay until it runs into something else. And well
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it's also creating a gravity, yes, I meet. And yeah,
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and then did they just push against each other and
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create that?
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As you know, they can cancel out because exactly as
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you've said, that's how the brunch points work.
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Yes, m M. It's really interesting and it adds more
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to the empty vessel that is our knowledge of gravity.
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It is should really don't understand gravity. Yeah, we just
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know it's there. It's it's one of those I suppose
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if someone ever figures it out, that's a Nobel prize
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waiting the hell on, isn't it?
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Definitely? Well, it will be quite when quantum gravity really
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comes of age, when we really understand quantum gravity, which
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we don't at the moment.
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So yeah, that will meet right. Thank you, Dean and
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all the best. Thanks for your question. This is Space
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Nuts Andrew Dunkley here with Professor Fairy Watson. Space Nuts.
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We've got another text question, Fred, and this one comes
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from Daniel who is in Adelaide, and he said, I've
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saved up a few quick fire questions I'm hoping you
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could answer please. Yes, we'd be happy to do so.
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So we'll knock them all off one at a time.
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Quick fire means you don't have to spend too much
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time on them. Fred, we know the universe's expansion has
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been accelerating for about the last five billion years. Given
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the night sky seems fairly full of stars to the
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naked eye today, what would it have looked like if
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you were standing on Earth when it formed? Would the
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night sky have been as bright as day? For example?
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That's his first question.
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Yeah, the answers no, So our vantage point four point
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six billion years ago when the Earth was forming, would
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be similar to what it is today. Yes, galaxies are
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closer together, and they might be, you know, a little
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bit brighter than we see them now, but I think
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it would still be a similar sky that we'd see.
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You've got to go back a lot further in time
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to be able to see a night sky as bright
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as day. And what that is is still being able
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to see the flash of the Big Bang, And at
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the moment, that flash of the Big Bang has been
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redshifted into microwaves, which is why we don't see a
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brilliant sky. But we would if our eyes were sensitive
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to microwaves, or if we were looking at the early universe,
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you know, not long after it became transparent, then we'd
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see a very bright sky.
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That just a totally unrelated question, but that just prompted
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in my mind a thought about animals and insects. Would
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they see the night sky completely differently to us?
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That's what some of Mani's work is about. She works
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on that sort of thing from the point of view
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of light pollution. Yes, they do. They're sensitive. Many of
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them are sensitive to different wavebands than what we are,
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and in fact, something in sex need the night sky.
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Dung beetles work by aligning the direction of trouble with
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