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Cosmic Curiosities: Q&A on White Holes and Dark Matter Mysteries
In this engaging Q&A episode of Space Nuts, temporary host Heidi Campo and Professor Fred Watson dive into a series of thought-provoking listener questions that explore the enigmatic realms of astrophysics and cosmology. From the theoretical nature of white holes to the perplexities of dark matter, this episode is packed with insights that challenge our understanding of the universe.
Episode Highlights:
- Understanding White Holes: The episode kicks off with a question from Casey in Colorado about the theoretical existence of white holes. Fred explains the concept, discussing their potential properties and what might lie within them, while highlighting the lack of evidence for their existence in our universe.
- Time Dilation and the Twins Paradox: Martin from an earlier episode prompts a discussion on time dilation and the implications of acceleration in the twins paradox scenario. Fred elaborates on the differences between special and general relativity and how acceleration plays a crucial role in understanding the phenomenon.
- Cosmic Microwave Background and Black Holes: Ash from Brisbane asks about the connection between the observable universe and black holes, referencing Roger Penrose's theories. Fred shares insights from recent discussions at a conference, exploring the intriguing idea of whether the cosmic microwave background could represent the inside of an event horizon.
- The Mystery of Dark Matter: Rennie from California poses a profound question about the nature of dark matter and its lack of interaction with light. Fred delves into the ongoing mysteries surrounding dark matter, discussing theories and the implications of its gravitational effects on 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.
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00:00:00 --> 00:00:02 Heidi Campo: Welcome back to another fun and exciting
00:00:02 --> 00:00:05 Q and A episode of space nuts.
00:00:05 --> 00:00:07 Voice Over Guy: 15 seconds. Guidance is internal.
00:00:08 --> 00:00:10 10, 9. Ignition
00:00:10 --> 00:00:13 sequence start. Space nuts. 5, 4, 3,
00:00:13 --> 00:00:16 2, 1. 3, 3, 4, 5, 5, 4,
00:00:16 --> 00:00:19 3, 2', 1. Space nuts. Astronauts
00:00:19 --> 00:00:20 report it feels good.
00:00:21 --> 00:00:24 Heidi Campo: I am your temporary host, Heidi,
00:00:24 --> 00:00:27 joining you today with Professor Fred Watson,
00:00:27 --> 00:00:30 astronomer at large, while our
00:00:30 --> 00:00:32 usual host, Andrew Dunkley, is off on his
00:00:32 --> 00:00:35 world cruise, having a grand old time.
00:00:36 --> 00:00:38 Ah, Fred, how are you doing today?
00:00:38 --> 00:00:40 Professor Fred Watson: I'm very well, thank you. Um, ah, still
00:00:40 --> 00:00:43 inundated with people interested in the end
00:00:43 --> 00:00:46 of the universe, which we talked about a few
00:00:46 --> 00:00:49 episodes ago. Uh, so that's good to know
00:00:49 --> 00:00:51 that, um, uh, people are taking some notice
00:00:51 --> 00:00:54 of the fact that 20 billion years might be
00:00:54 --> 00:00:57 the, uh, closing down ceremony for the
00:00:57 --> 00:00:59 universe. We'll cover that in Space Nuts.
00:00:59 --> 00:01:02 Heidi Campo: Obviously we'll talk about the end
00:01:02 --> 00:01:02 of the universe.
00:01:03 --> 00:01:06 Well, today, um, we've got more great
00:01:06 --> 00:01:08 questions. I always say that our questions
00:01:08 --> 00:01:11 are what makes up half the show? And our very
00:01:11 --> 00:01:14 first question of our episode
00:01:14 --> 00:01:16 today comes from Casey. From my side
00:01:16 --> 00:01:19 of the world, from Colorado, which is a
00:01:19 --> 00:01:22 beautiful state. And I always tell people if
00:01:22 --> 00:01:24 you see beautiful pictures of the mountains,
00:01:24 --> 00:01:26 they're definitely from Colorado, not from
00:01:26 --> 00:01:28 Utah. Utah's full. Don't go.
00:01:30 --> 00:01:32 So Casey from Colorado says,
00:01:33 --> 00:01:35 hi, guys. I know that white holes are
00:01:35 --> 00:01:38 basically the opposite of black in the way
00:01:38 --> 00:01:41 that nothing can enter them. I understand
00:01:41 --> 00:01:43 that at this point they are completely
00:01:43 --> 00:01:45 theoretical and we haven't actually found
00:01:45 --> 00:01:48 any. If we did find one, what
00:01:48 --> 00:01:51 would be inside of it? Would it have mass?
00:01:51 --> 00:01:54 How does gravity work in and around it? Love
00:01:54 --> 00:01:56 the show and hope you're both well. Thanks.
00:01:57 --> 00:01:59 Professor Fred Watson: That's great. Thanks. Thanks. Thanks very
00:01:59 --> 00:02:01 much, Casey. And, uh, it's a good question.
00:02:02 --> 00:02:05 Um, uh, it's probably about 30 years
00:02:05 --> 00:02:07 ago that white holes were all the rage.
00:02:07 --> 00:02:10 People were talking about them endlessly.
00:02:11 --> 00:02:13 Uh, and, uh, I guess what that did
00:02:14 --> 00:02:16 was set up people looking for them. And we've
00:02:16 --> 00:02:19 never found any, any evidence of one. Uh, but
00:02:19 --> 00:02:21 the reason why people think that they might
00:02:22 --> 00:02:24 exist is that there's nothing
00:02:25 --> 00:02:28 in the equations of relativity,
00:02:28 --> 00:02:30 which is what govern the behavior of black
00:02:30 --> 00:02:33 holes and space. And generally. It's
00:02:33 --> 00:02:36 Einstein's theory of gravity. Uh, there's
00:02:36 --> 00:02:38 nothing in that that says that you can't
00:02:38 --> 00:02:41 have, uh, a sort of opposite object
00:02:41 --> 00:02:44 to a black hole. And what you have to
00:02:44 --> 00:02:46 do in the equations is reverse the direction
00:02:46 --> 00:02:49 that time works in. Uh, and if you
00:02:49 --> 00:02:52 switch that round and yes, that's hard to get
00:02:52 --> 00:02:54 your head around at all. But if you do
00:02:54 --> 00:02:57 that, put negative time in instead of a black
00:02:57 --> 00:02:59 hole, you get a white hole. Uh, and so
00:03:00 --> 00:03:03 the theoretical physicists said there's
00:03:03 --> 00:03:06 nothing that we can find that would
00:03:06 --> 00:03:09 rule out the existence of these objects, that
00:03:09 --> 00:03:12 they, they may exist. And then
00:03:12 --> 00:03:15 there was the connection that perhaps two
00:03:15 --> 00:03:17 black holes or two white holes, or a black
00:03:17 --> 00:03:19 hole and a white hole could, could connect
00:03:19 --> 00:03:21 with each other to make a wormhole, which
00:03:21 --> 00:03:23 might give us a way of getting from one side
00:03:23 --> 00:03:25 of the universe to the other very quickly.
00:03:25 --> 00:03:27 Um, I think you'd risk all kinds of horrible
00:03:27 --> 00:03:29 things happening if you did that. But anyway,
00:03:29 --> 00:03:32 uh, that's the idea. So, uh, the quest
00:03:32 --> 00:03:35 was on, uh, for uh, you
00:03:35 --> 00:03:37 know, looking for evidence of white holes,
00:03:37 --> 00:03:39 which you would think,
00:03:40 --> 00:03:42 unlike a black hole, would be very bright.
00:03:42 --> 00:03:45 Uh, and um, so far we
00:03:45 --> 00:03:48 found nothing, no evidence of anything
00:03:48 --> 00:03:51 that would correlate with the, you
00:03:51 --> 00:03:53 know, the um, observations that
00:03:54 --> 00:03:56 physicists, um, suggest might be made of a,
00:03:56 --> 00:03:59 uh, of a, of a white hole. Um, if we
00:03:59 --> 00:04:02 did find one, as, as Casey asks, uh,
00:04:02 --> 00:04:05 what would be inside it? Well, yeah, it's
00:04:05 --> 00:04:08 hard to know, uh, because, you know, black
00:04:08 --> 00:04:10 holes, it's a one way process for stuff going
00:04:10 --> 00:04:13 in. Uh, with a white hole, as you say,
00:04:13 --> 00:04:15 Casey, it's a one way process with stuff
00:04:15 --> 00:04:18 coming out. Uh, so where's that stuff come
00:04:18 --> 00:04:21 from? What's inside it? Where has
00:04:21 --> 00:04:23 the material that might
00:04:23 --> 00:04:26 be escaping from it? If it was, uh,
00:04:27 --> 00:04:30 where did that, where did that come from?
00:04:30 --> 00:04:32 Maybe from a wormhole, maybe just from
00:04:32 --> 00:04:35 sucking it in from the fabric of space. Um,
00:04:35 --> 00:04:38 I'm not qualified enough in relativistic
00:04:38 --> 00:04:40 theory to be able to give you an answer to
00:04:40 --> 00:04:42 that. Um, would it have mass? Yes, I think it
00:04:42 --> 00:04:45 would. Um, I think the mass
00:04:45 --> 00:04:47 is one of the constants in the equations
00:04:48 --> 00:04:51 of the white hole. So I think the answer is
00:04:51 --> 00:04:53 it would have mass and so gravity would
00:04:53 --> 00:04:56 probably work around it in the same way
00:04:56 --> 00:04:59 as a black hole does. I'm sort of speculating
00:04:59 --> 00:05:01 here, Casey. Uh, these are not authoritative
00:05:01 --> 00:05:04 answers because I have, have not had a look
00:05:04 --> 00:05:06 at the white hole theory for a long time.
00:05:07 --> 00:05:09 But I think you can draw all kinds of
00:05:09 --> 00:05:12 comparisons. It's a, there's an analog,
00:05:12 --> 00:05:14 you know, from, from a black hole to a white
00:05:14 --> 00:05:17 hole. Uh, the fact that we've never found
00:05:17 --> 00:05:20 anything that has symptomatic, uh, or is
00:05:20 --> 00:05:22 symptomatic of the existence of a white hole
00:05:22 --> 00:05:24 probably means that in reality they don't
00:05:24 --> 00:05:27 exist. Um, but we're always open to
00:05:27 --> 00:05:28 suggestions.
00:05:29 --> 00:05:31 Heidi Campo: We could just be in the wrong universe for
00:05:31 --> 00:05:31 them.
00:05:32 --> 00:05:34 Professor Fred Watson: That's true. Uh, in a different universe,
00:05:34 --> 00:05:36 maybe white Holes are everywhere. Yes, quite
00:05:36 --> 00:05:36 so.
00:05:37 --> 00:05:39 Heidi Campo: And they can't find any black holes. There's
00:05:39 --> 00:05:42 some podcast where there's a
00:05:42 --> 00:05:44 Fred interviewing a Fred's interviewing
00:05:44 --> 00:05:46 Heidi and they're wondering, well, why can't
00:05:46 --> 00:05:48 we find these theoretical black holes?
00:05:48 --> 00:05:50 Professor Fred Watson: Yeah, that's right. And time's running
00:05:50 --> 00:05:51 backwards for us.
00:05:52 --> 00:05:54 Heidi Campo: Yeah, uh, we're getting younger.
00:05:55 --> 00:05:55 Professor Fred Watson: That'd be good.
00:05:57 --> 00:05:59 Heidi Campo: Our next question, um, you must have listened
00:05:59 --> 00:06:01 to a few episodes ago where we were talking
00:06:01 --> 00:06:04 about name history. Um, this is from
00:06:04 --> 00:06:07 Martin. Martin says hi
00:06:07 --> 00:06:09 Adelheid and Frederick. I
00:06:09 --> 00:06:12 just listened to your latest episode Stellar
00:06:12 --> 00:06:14 Questions and um, the very first one puzzled
00:06:14 --> 00:06:17 me. This is about time dilation.
00:06:17 --> 00:06:20 The formula Fred used for calculations
00:06:20 --> 00:06:22 takes into account only velocity.
00:06:23 --> 00:06:25 Isn't it only for observation dilation.
00:06:26 --> 00:06:28 The reason it puzzles me is that the scenario
00:06:28 --> 00:06:31 was traveler returns back to Earth.
00:06:31 --> 00:06:34 Isn't that more like twin paradox?
00:06:34 --> 00:06:37 And the differences should be explained by
00:06:37 --> 00:06:39 acceleration because without acceleration
00:06:40 --> 00:06:42 and given the velocity is relative, we
00:06:42 --> 00:06:45 couldn't tell if it was the astronaut who
00:06:45 --> 00:06:47 traveled or the Earth who went for a trip and
00:06:47 --> 00:06:50 returned to a, uh, stationary protagonist.
00:06:50 --> 00:06:53 I hope I'm not completely off. Great work
00:06:53 --> 00:06:54 with the podcast, I love it.
00:06:56 --> 00:06:58 Professor Fred Watson: And Martin, great work on the question
00:06:58 --> 00:07:00 because everything you've said is absolutely
00:07:00 --> 00:07:02 correct. Um, I just didn't say all that
00:07:02 --> 00:07:04 because didn't seem as though there was time
00:07:04 --> 00:07:07 to do it. But yeah, um, you're right. Um,
00:07:07 --> 00:07:10 um, you've got to have for the twins paradox
00:07:10 --> 00:07:13 to work. And that's where one twin goes off
00:07:13 --> 00:07:15 on a long journey into space very quickly at
00:07:15 --> 00:07:18 what was it, 9995% of the
00:07:18 --> 00:07:21 speed of light. If you want to have a 100
00:07:21 --> 00:07:24 year ratio or 100 to 1 ratio,
00:07:24 --> 00:07:27 uh, um, the astronaut goes
00:07:27 --> 00:07:30 off, uh, uh, visits a
00:07:30 --> 00:07:33 distant star, takes their photographs
00:07:33 --> 00:07:35 and with their smartphone and all the rest of
00:07:35 --> 00:07:37 it comes back to Earth. Uh, the
00:07:37 --> 00:07:40 Earth has aged by 100 years and the astronaut
00:07:40 --> 00:07:43 has only aged by a year. Um, that's called
00:07:43 --> 00:07:45 the twins paradox because you imagine that
00:07:45 --> 00:07:48 it's would be two twins who were being
00:07:48 --> 00:07:50 separated like that. Uh, and
00:07:51 --> 00:07:54 it only works because of
00:07:55 --> 00:07:58 the accelerative component. So uh, the
00:07:58 --> 00:08:01 answer I gave was purely special
00:08:01 --> 00:08:03 relativity. That's simply, um,
00:08:04 --> 00:08:06 you know, relativity, uh, with
00:08:06 --> 00:08:08 motion at a constant speed.
00:08:09 --> 00:08:11 Uh, so clearly you're not going at a constant
00:08:11 --> 00:08:12 speed. If you turn around and come back
00:08:12 --> 00:08:15 again, uh, you've got a deceleration and then
00:08:15 --> 00:08:18 an acceleration. And those are the terms that
00:08:18 --> 00:08:20 allow the twins paradox to work. It's the
00:08:20 --> 00:08:22 fact that you're actually switching
00:08:22 --> 00:08:25 acceleration because that introduces, uh,
00:08:25 --> 00:08:28 geometrical, uh, elements which are
00:08:28 --> 00:08:30 more related to general
00:08:30 --> 00:08:33 relativity. And in fact, um, what
00:08:33 --> 00:08:36 I also didn't mention, um, so just
00:08:36 --> 00:08:38 to, um, fill you in, Martin, that,
00:08:39 --> 00:08:40 uh, there is more to the story. Exactly as
00:08:40 --> 00:08:43 you've said, uh, in general relativity,
00:08:43 --> 00:08:45 that's Einstein's second theory of
00:08:45 --> 00:08:48 relativity, the one that accounts for gravity
00:08:48 --> 00:08:50 and that lets black holes exist and white
00:08:50 --> 00:08:53 holes and all the rest of it. Um, that
00:08:53 --> 00:08:56 theory also has time dilation in it. In
00:08:56 --> 00:08:59 other words, uh, what it says is that if you
00:08:59 --> 00:09:01 get in a strong gravitational field, your
00:09:01 --> 00:09:04 clocks run more slowly as observed from
00:09:04 --> 00:09:06 outside than they would
00:09:07 --> 00:09:09 if you were just outside, uh, the
00:09:09 --> 00:09:11 gravitational field. So, for example, our
00:09:11 --> 00:09:13 clocks are running slightly more slowly than
00:09:14 --> 00:09:16 clocks on board spacecraft, uh, orbiting
00:09:16 --> 00:09:18 the Earth. And that has been measured, that
00:09:18 --> 00:09:21 time dilation has been measured. And I think
00:09:21 --> 00:09:24 it is taken into account in the
00:09:24 --> 00:09:27 GPS in your phones as well. I think you have
00:09:27 --> 00:09:28 to have those relativistic corrections in
00:09:28 --> 00:09:31 there for it to work. So. Yes. Good
00:09:31 --> 00:09:34 pickup. Thank you very much, uh, Martin.
00:09:34 --> 00:09:37 Uh, and, um, thanks also for giving my Sunday
00:09:37 --> 00:09:39 Best name as well. Uh, very few people call
00:09:39 --> 00:09:42 me Frederic. It's usually people in banks or
00:09:42 --> 00:09:44 in medical reception areas
00:09:45 --> 00:09:47 because that's my full name. Is your full
00:09:47 --> 00:09:48 name Adelheid? Heidi?
00:09:49 --> 00:09:51 Heidi Campo: My full name is Heidi, but the, uh, name
00:09:51 --> 00:09:54 comes from Adelheid, um,
00:09:54 --> 00:09:57 which I believe means noble
00:09:57 --> 00:10:00 is the kind of the history of the name.
00:10:01 --> 00:10:04 Um, but I know it's a German name. I know
00:10:04 --> 00:10:06 my mother read the book Heidi when she was
00:10:06 --> 00:10:09 young and she loved the character. So that's
00:10:09 --> 00:10:11 how I got the name Heidi. Despite. I'm
00:10:11 --> 00:10:13 actually, um, my, my family heritage is
00:10:13 --> 00:10:16 Italian. I'm, I'm second generation
00:10:16 --> 00:10:19 Sicilian. So I still have family in Sicily,
00:10:19 --> 00:10:22 but I have a German first name, an Italian
00:10:22 --> 00:10:25 last name and an Irish husband. So I'm a, uh,
00:10:25 --> 00:10:26 classic American, you can say.
00:10:26 --> 00:10:28 Professor Fred Watson: Yeah, that's good.
00:10:32 --> 00:10:33 Heidi Campo: Space nuts.
00:10:33 --> 00:10:36 Our next question is, uh, from
00:10:36 --> 00:10:39 Ash from Bris Brisbane. And
00:10:39 --> 00:10:42 Ash says, hi, Heidi and Fred. I hope this
00:10:42 --> 00:10:44 message finds you well. I recently came
00:10:44 --> 00:10:47 across a statement by Professor Brian Greene
00:10:47 --> 00:10:50 regarding the observable universe
00:10:50 --> 00:10:53 being 93 billion light years across.
00:10:53 --> 00:10:56 He mentioned that if we were to condense the
00:10:56 --> 00:10:59 known mass of the observable universe into
00:10:59 --> 00:11:01 theoretical black hole, the
00:11:01 --> 00:11:03 calculations suggest that the event horizon
00:11:03 --> 00:11:06 would align with the distance of the
00:11:06 --> 00:11:08 cosmic microwave background.
00:11:09 --> 00:11:11 This leads me to wonder, is Roger Penrose
00:11:11 --> 00:11:14 correct in his theories? Could the cmb,
00:11:15 --> 00:11:17 the cosmic microwave background, actually
00:11:17 --> 00:11:19 represent the inside of an event
00:11:19 --> 00:11:22 horizon? And that's why we cannot
00:11:22 --> 00:11:25 penetrate it? Is this just One big
00:11:25 --> 00:11:28 universe sized coincidence. I'm
00:11:28 --> 00:11:29 looking forward to hearing your thoughts on
00:11:29 --> 00:11:31 this intriguing topic.
00:11:33 --> 00:11:35 Professor Fred Watson: That's great. Thanks for that, Ash. Uh, um,
00:11:35 --> 00:11:38 we did talk about the idea, uh, of the
00:11:38 --> 00:11:41 universe being a black hole or inside a black
00:11:41 --> 00:11:43 hole, I, uh, think in the last Q and A
00:11:43 --> 00:11:46 episode. But I was talking last night to some
00:11:46 --> 00:11:47 of my colleagues at the conference that I'm
00:11:47 --> 00:11:49 at at the moment, Astronomical Society of
00:11:49 --> 00:11:52 Australia's annual science meeting about
00:11:52 --> 00:11:55 this, um, and um, I think
00:11:56 --> 00:11:58 the general
00:11:58 --> 00:12:00 opinion was
00:12:01 --> 00:12:04 basically what you've said, Ash, at the end
00:12:04 --> 00:12:06 of your question there. Is this just
00:12:06 --> 00:12:09 one big universe sized coincidence?
00:12:09 --> 00:12:12 I think, uh, everybody thinks that,
00:12:12 --> 00:12:15 um, it's drawing a long bow
00:12:15 --> 00:12:18 to assume that we might be inside a
00:12:18 --> 00:12:20 black hole, uh,
00:12:21 --> 00:12:24 only by the fact that the universe,
00:12:26 --> 00:12:28 effectively what we call the proper distance
00:12:28 --> 00:12:30 to the event, sorry, the cosmic microwave
00:12:30 --> 00:12:33 background radiation would be about the size
00:12:33 --> 00:12:36 of the event horizon, uh, if the mass
00:12:36 --> 00:12:38 of the observable universe was in a black
00:12:38 --> 00:12:41 hole. So, uh, that's one strand
00:12:41 --> 00:12:43 to this, but you've highlighted another one
00:12:43 --> 00:12:46 as well. As with Roger Penrose, his ideas are
00:12:46 --> 00:12:49 very much concerned with, um, big
00:12:49 --> 00:12:52 bangs coming from black holes
00:12:52 --> 00:12:55 detonating in a universe that just keeps
00:12:55 --> 00:12:57 on going. So we've got this multiple multi
00:12:57 --> 00:13:00 universe idea again, the multiverse with
00:13:01 --> 00:13:03 supermassive, uh, black holes or hyper
00:13:03 --> 00:13:05 massive black holes popping off everywhere.
00:13:05 --> 00:13:08 And each one forms its own universe, uh,
00:13:08 --> 00:13:10 inside it, and we're inside one of those.
00:13:10 --> 00:13:12 It's a nice theory. Again,
00:13:14 --> 00:13:16 very, uh, speculative. There's no
00:13:16 --> 00:13:19 evidence to, in fact, it's hard to
00:13:19 --> 00:13:22 imagine what the evidence might be to prove
00:13:22 --> 00:13:24 that. We have people working on
00:13:24 --> 00:13:26 the idea of multiverses and indeed
00:13:28 --> 00:13:30 the Penrose theories as well. Um, but it's
00:13:30 --> 00:13:33 very hard to think what evidence you might
00:13:33 --> 00:13:36 bring to bear on that that says yes or no,
00:13:36 --> 00:13:39 uh, about living in a black hole. Um, it's a
00:13:39 --> 00:13:41 nice coincidence though, this, uh, you know,
00:13:41 --> 00:13:43 the radius of the universe being
00:13:43 --> 00:13:45 approximately the radius of the event horizon
00:13:45 --> 00:13:48 of a black hole. I think that's all it is,
00:13:48 --> 00:13:48 though.
00:13:48 --> 00:13:50 Heidi Campo: We may never know.
00:13:50 --> 00:13:52 Professor Fred Watson: We may never know. That's right.
00:13:55 --> 00:13:57 0G. And I feel fine.
00:13:57 --> 00:13:58 Heidi Campo: Space nuts.
00:13:58 --> 00:14:00 Well, what I do know is that our last
00:14:00 --> 00:14:02 question of the day is from one of our
00:14:02 --> 00:14:05 regular listener listeners. I can
00:14:05 --> 00:14:07 still talk. I haven't gotten fatigued. I
00:14:07 --> 00:14:09 usually get a couple audio questions mixed
00:14:09 --> 00:14:12 in. That's all these written questions. I'm
00:14:12 --> 00:14:14 doing more talking, but I can still say that
00:14:14 --> 00:14:16 our last question is from Rennie Trabb from
00:14:16 --> 00:14:19 Sunny Hills West, California. Sunny
00:14:19 --> 00:14:22 West Hills, California. Maybe I losing my
00:14:22 --> 00:14:24 Ability to talk. But it's good because this
00:14:24 --> 00:14:26 is a short question and Rennie says it
00:14:26 --> 00:14:29 seems that there is a purpose for why the
00:14:29 --> 00:14:31 universe is the way it is. What are your
00:14:31 --> 00:14:34 thoughts on why dark matter functions the way
00:14:34 --> 00:14:36 it does and the need for it to not
00:14:36 --> 00:14:39 react with the light, but, but yet it reacts
00:14:39 --> 00:14:41 to our matter in the universe?
00:14:42 --> 00:14:45 Professor Fred Watson: Yeah, uh, I mean, this is a really deep,
00:14:45 --> 00:14:48 deep question, uh, which is sort
00:14:48 --> 00:14:51 of concealed in some, you know,
00:14:51 --> 00:14:53 very innocent language. I think it's a
00:14:53 --> 00:14:56 beautiful question, Rennie, as yours always
00:14:56 --> 00:14:59 are. Um, so that,
00:14:59 --> 00:15:01 that first sentence, it seems there is a
00:15:01 --> 00:15:03 purpose for why the universe is the way it
00:15:03 --> 00:15:05 is. Um, I think the way I
00:15:05 --> 00:15:08 would look at that, uh, is the
00:15:08 --> 00:15:11 other way around. That, uh,
00:15:17 --> 00:15:19 it's something called the, uh, strong
00:15:19 --> 00:15:22 anthropic principle that says
00:15:22 --> 00:15:25 that, uh, we can
00:15:25 --> 00:15:28 observe the universe because we
00:15:28 --> 00:15:31 are here. It's a, you know, it's
00:15:31 --> 00:15:33 almost like a non sequitur, something that
00:15:33 --> 00:15:36 just doesn't follow. Uh, but what it's saying
00:15:36 --> 00:15:38 is that we are here
00:15:39 --> 00:15:42 because the universe has certain
00:15:42 --> 00:15:45 physical properties. And it's the laws of
00:15:45 --> 00:15:48 physics that let stars form, galaxies
00:15:48 --> 00:15:51 form, planets form. You know,
00:15:51 --> 00:15:54 humans form all the rest of it. Uh, that
00:15:54 --> 00:15:57 is, um, to say that
00:15:57 --> 00:15:59 it looks as though we live in a universe that
00:15:59 --> 00:16:02 is fine tuned for life. That if these
00:16:02 --> 00:16:05 physical, uh, constants were
00:16:05 --> 00:16:06 different, particularly if the speed of light
00:16:06 --> 00:16:08 was different or the charge on the electron
00:16:08 --> 00:16:11 was different or whatever, uh, the universe
00:16:11 --> 00:16:13 might never have been able to form planets.
00:16:13 --> 00:16:16 It might have either been so short that it
00:16:16 --> 00:16:18 collapsed on itself almost immediately, uh,
00:16:18 --> 00:16:21 or it may have been so
00:16:21 --> 00:16:24 rarefied that atoms never came together to
00:16:24 --> 00:16:26 react and form molecules and make up the
00:16:26 --> 00:16:29 ingredients for life. So it's this fine
00:16:29 --> 00:16:31 tuning, as I said, it's the anthropic
00:16:31 --> 00:16:34 principle. Um, and so in a way
00:16:34 --> 00:16:37 you can interpret that is as the universe
00:16:37 --> 00:16:40 having. Let me just read your sentence again.
00:16:40 --> 00:16:42 A purpose for why the universe is the way it
00:16:42 --> 00:16:45 is. Uh, its purpose is
00:16:45 --> 00:16:48 perhaps a strong word, but, um, it's saying
00:16:48 --> 00:16:51 the universe is the way it is. It
00:16:51 --> 00:16:53 allows us to be in it. If there was a
00:16:53 --> 00:16:55 different universe that we're in, we wouldn't
00:16:55 --> 00:16:57 be here, so we wouldn't be able to observe
00:16:57 --> 00:17:00 it. Uh, so I think that's a
00:17:00 --> 00:17:02 fascinating question. It's one that's been
00:17:02 --> 00:17:04 written about a lot. Uh, the anthropic
00:17:04 --> 00:17:05 principle.
00:17:05 --> 00:17:08 Um, what are my thoughts on why dark matter
00:17:08 --> 00:17:10 functions the way it does and the need for it
00:17:10 --> 00:17:12 not to react with light, but yet it reacts to
00:17:12 --> 00:17:15 our matter in the universe? Look, that's just
00:17:15 --> 00:17:17 a huge mystery, um, that
00:17:18 --> 00:17:20 um, we have this, these
00:17:20 --> 00:17:22 observations that suggest that there is
00:17:22 --> 00:17:24 something in the universe that has
00:17:24 --> 00:17:26 gravitational, uh, attraction.
00:17:26 --> 00:17:28 It attracts things. It's
00:17:29 --> 00:17:32 got enough gravity that it stops galaxies
00:17:32 --> 00:17:34 from flying apart because their rotation's
00:17:34 --> 00:17:36 too high. Uh, and yet
00:17:37 --> 00:17:40 it does not interact in any way
00:17:41 --> 00:17:43 in any of the other properties. So it
00:17:43 --> 00:17:46 doesn't, uh, have any reaction, as
00:17:46 --> 00:17:48 you say, with light, electromagnetic
00:17:48 --> 00:17:50 radiation. So for example, it doesn't block
00:17:50 --> 00:17:52 out the light. Light coming behind it would
00:17:53 --> 00:17:55 be very handy if it did. Then we could
00:17:55 --> 00:17:57 actually see it and measure its properties.
00:17:57 --> 00:18:00 Um, what we have to do is look at the
00:18:00 --> 00:18:03 way, uh, it does interact with light, which
00:18:03 --> 00:18:06 is through gravity. Uh, that means, uh,
00:18:07 --> 00:18:08 it can act as a lens. If you've got a large
00:18:08 --> 00:18:11 blob of dark matter, it can act as a
00:18:11 --> 00:18:13 gravitational lens, which means it will focus
00:18:13 --> 00:18:15 light and let us see magnified images of very
00:18:15 --> 00:18:18 distant galaxies if you've got a large blob
00:18:18 --> 00:18:21 of dark matter around a cluster of galaxies
00:18:21 --> 00:18:23 in the foreground. Because we do know that
00:18:23 --> 00:18:25 dark matter is where normal matter is.
00:18:26 --> 00:18:28 Wherever there's normal matter, there is dark
00:18:28 --> 00:18:30 matter, except in a very few cases.
00:18:31 --> 00:18:34 So, uh, yeah, it's still a mystery and it
00:18:34 --> 00:18:37 is still possible, um, uh,
00:18:38 --> 00:18:40 that we've got it wrong, that
00:18:41 --> 00:18:44 there is something else going on, uh, that
00:18:44 --> 00:18:46 that negates the need to have dark matter
00:18:48 --> 00:18:50 as a property of the universe. And one of
00:18:50 --> 00:18:53 those things is something studied by a friend
00:18:53 --> 00:18:55 and colleague of mine, Peter Verwein. He's
00:18:55 --> 00:18:58 uh, still, I think, writing his PhD thesis
00:18:58 --> 00:19:00 on a theory called MON Modified, um,
00:19:01 --> 00:19:03 Newtonian dynamics, uh, which
00:19:04 --> 00:19:06 suggests that, uh, at very low
00:19:06 --> 00:19:09 accelerations, uh, which are the kind that
00:19:09 --> 00:19:12 are experienced by stars going in
00:19:12 --> 00:19:14 orbit around the center of a galaxy, for
00:19:14 --> 00:19:17 example, at very low accelerations, our, uh,
00:19:17 --> 00:19:20 normal understanding of Newtonian physics
00:19:20 --> 00:19:22 breaks down. So MOND is Modified Newtonian
00:19:22 --> 00:19:25 Dynamics, uh, and it was introduced
00:19:25 --> 00:19:28 back in the 1980s when dark energy was first
00:19:28 --> 00:19:31 postulated by a scientist,
00:19:31 --> 00:19:34 uh, whose name was Mordechai Milgrom. Uh, he
00:19:34 --> 00:19:36 introduced the idea and it's been floating
00:19:36 --> 00:19:39 around ever since. M why isn't it accepted
00:19:39 --> 00:19:42 generally as the main reason why the galaxy
00:19:42 --> 00:19:44 behaves like it does and why the universe as
00:19:44 --> 00:19:46 a whole behaves like it does? Uh, that's
00:19:46 --> 00:19:49 because, um, if you tinker around with
00:19:49 --> 00:19:51 Newtonian dynamics, a lot of other things
00:19:51 --> 00:19:53 don't make sense. Uh, the early universe
00:19:53 --> 00:19:55 doesn't make sense. Globular clusters don't
00:19:55 --> 00:19:57 make sense. And so that's why it's not
00:19:57 --> 00:20:00 popular. Uh, but it's still possible that we
00:20:00 --> 00:20:02 might be missing something. Maybe there is
00:20:02 --> 00:20:05 something out there that makes us think
00:20:05 --> 00:20:07 we're surrounded by dark matter and we're
00:20:07 --> 00:20:10 not. So, uh, scientists have to be open
00:20:10 --> 00:20:12 minded about that. Uh, not so open minded
00:20:12 --> 00:20:14 that your brains fall out, as somebody once
00:20:14 --> 00:20:16 said. Uh, but open minded enough that you can
00:20:16 --> 00:20:19 recognize any possibility. And I think that's
00:20:19 --> 00:20:21 really what, what my thoughts would be
00:20:22 --> 00:20:23 in the questions that you've asked Rennie.
00:20:23 --> 00:20:26 And thanks again for very profound and
00:20:26 --> 00:20:28 thought provoking questions.
00:20:29 --> 00:20:31 Heidi Campo: You guys did a great job with your questions
00:20:31 --> 00:20:34 this week and Fred did a great job as always
00:20:34 --> 00:20:37 answering them and I am just so grateful
00:20:37 --> 00:20:39 to be a part of this journey.
00:20:39 --> 00:20:42 Fred, um, do you have any, um, we got,
00:20:42 --> 00:20:44 you know, maybe we can give another minute.
00:20:45 --> 00:20:46 Do you have anything that you really have
00:20:46 --> 00:20:49 enjoyed from this conference that's been like
00:20:49 --> 00:20:50 some of your highlights?
00:20:51 --> 00:20:54 Professor Fred Watson: Yeah. So, uh, the session that um,
00:20:54 --> 00:20:56 I was really keen to be at was
00:20:57 --> 00:21:00 yesterday. And it's about the
00:21:00 --> 00:21:02 things that I lose sleep over. Uh,
00:21:03 --> 00:21:05 how is Australia going to, uh,
00:21:05 --> 00:21:07 be involved with the next generation of large
00:21:07 --> 00:21:10 telescopes, large visible light telescopes?
00:21:10 --> 00:21:13 These are things that um, might seem a bit
00:21:13 --> 00:21:15 pedestrian when you compare it with the other
00:21:15 --> 00:21:17 stuff that's going on at a conference. Uh,
00:21:17 --> 00:21:20 there's a lot of really interesting new
00:21:20 --> 00:21:23 science coming out. And one of
00:21:23 --> 00:21:25 them that I sort of seem to pick up a lot
00:21:25 --> 00:21:28 on is the idea of how, how galaxies
00:21:28 --> 00:21:31 work, how the um, the
00:21:31 --> 00:21:33 outflows of gas from their black holes at the
00:21:33 --> 00:21:35 center. This is particularly in the early
00:21:35 --> 00:21:38 universe, how that uh, can interact with
00:21:38 --> 00:21:41 the gases that are forming stars. Uh, there's
00:21:41 --> 00:21:43 a process called quenching, which is where
00:21:43 --> 00:21:46 these winds that are blown out by black holes
00:21:46 --> 00:21:49 actually blow out the star formation
00:21:49 --> 00:21:52 process. So, uh, you get the star formation
00:21:52 --> 00:21:54 process quenched. And that's something that
00:21:54 --> 00:21:56 still has a lot of research going on with it.
00:21:56 --> 00:21:58 That was certainly one of the hot topics
00:21:58 --> 00:22:00 yesterday. Uh, but um, my
00:22:00 --> 00:22:03 fascination is always with, uh, because
00:22:03 --> 00:22:06 basically I'm a telescope man. Uh, it's what
00:22:06 --> 00:22:09 I did all my life. I ran telescopes, uh, for
00:22:09 --> 00:22:11 a lot of my life. Uh, and I'm always
00:22:11 --> 00:22:14 interested in where our country is going in
00:22:14 --> 00:22:16 regard to the facilities that it needs so our
00:22:16 --> 00:22:19 astronomers can make these discoveries of the
00:22:19 --> 00:22:21 kind that we've been talking about today. Um,
00:22:22 --> 00:22:24 so that was, I think, the highlight of the
00:22:24 --> 00:22:27 conference for me. Um, some of the news is
00:22:27 --> 00:22:30 good, some of it's not so good. Uh, of course
00:22:30 --> 00:22:32 all facilities for astronomy rely on funding
00:22:32 --> 00:22:34 and it tends to be governments that do that
00:22:34 --> 00:22:37 funding because many of the arrangements are
00:22:37 --> 00:22:39 bound by international treaties, which have
00:22:39 --> 00:22:40 to be signed by governments and not private
00:22:41 --> 00:22:44 individuals. So we will see where this
00:22:44 --> 00:22:47 all goes. And, um, certainly on Space Nuts,
00:22:47 --> 00:22:49 uh, we will keep everybody well aware of
00:22:49 --> 00:22:51 what's happening in the world of telescopes
00:22:51 --> 00:22:53 and the world of astronomy generally.
00:22:54 --> 00:22:57 Heidi Campo: Thank you so much, Fred. Uh, it's been a
00:22:57 --> 00:22:59 pleasure chatting with you today, and thank
00:22:59 --> 00:23:01 you again to all of our listeners. And with
00:23:01 --> 00:23:04 that, we are going to wrap it up and say good
00:23:04 --> 00:23:06 night till the next time.
00:23:06 --> 00:23:07 Professor Fred Watson: Good night and good morning.
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