First stop: the mysterious Lagrange points. Listener Jim from Texas is puzzled about how gravity is balanced at these points, especially L2 and L3. Fred serves up a celestial explanation that involves not just gravity but centrifugal force, too. It's a cosmic balancing act that keeps our space missions on course and our minds in awe.
Next, we're zooming into the heart of galaxies where supermassive black holes reign supreme. Kerry's burning question leads us to differentiate the gravitational effects of these cosmic giants from the elusive dark matter. How do astronomers measure their impact separately, and could we have misjudged their mass? Fred illuminates the dark corners of this astronomical puzzle.
And for the grand finale, we're pondering the ultimate 'what if': communication with a superior alien race. If we could ask them just one question, what would it be? From the practical to the profound, Andrew and Fred muse over what could be humanity's most significant query.
Whether you're a cosmic rookie or a seasoned stargazer, this episode is guaranteed to provide a gravity-defying leap into the unknown. So, strap in and prepare for a journey that's as educational as it is entertaining. And remember, keep those questions coming – they just might be the next big topic on Space Nuts!
For all this and more, subscribe to Space Nuts on your favorite podcast platform, and join us on this stellar adventure. Until next time, keep your eyes to the skies and your hearts full of wonder.
Become a supporter of this podcast and access commercial-free episodes: https://www.spreaker.com/podcast/space-nuts--2631155/support.
00:00:00
Hello again. Thanks for joining us. This is Space Nuts. Coming
00:00:03
up. We're talking Lagrange Points, supermassive black
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holes, dark matter and a what if question about what, you know,
00:00:11
meeting aliens and what we would want to know from them all.
00:00:15
Coming up on this edition of Space Nuts, Space Nuts.
00:00:27
4321234554321. Space astronauts report. It feels good.
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Ok, Fred. Shall we tackle some questions?
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We should, shouldn't we?
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I guess so. No. Ok. Well, we've got a couple of text, a couple
00:00:44
of text questions to start off with. This one comes from Jim
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Skelly in Plano Texas. So I have a question about Lagrange points
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or Lagrange points. If we look at the five Lagrange points
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around the Earth and the sun, I can fully comprehend L one which
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is between the sun and the Earth.
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I can also understand L Four And L Five which are 60 degrees
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ahead of and behind the Earth's orbit respectively. Can readily
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see where the force of gravity between the sun and the Earth
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would be in balance at these three locations.
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I really struggle to understand L Three which is on the opposite
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side of the sun from the Earth and L Two, which is beyond the
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Earth and is a popular location for positioning telescopes like
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well, you know, the planket S T and, and the New European one
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that's gone up there too.
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I, I cannot understand how gravity between the Earth and
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the sun is balanced at L Two and L Three locations. Can you
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kindly enlighten me? Thank you for the answer. And the Great
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podcast that you produce each week. Well, it's not great every
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week. I can tell you. But, anyway, it's a bit sick today.
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They know they know about Adrian. You don't have to tell
00:02:01
him. It's not great. Everybody knows that.
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But no good question. And I must confess that this is one that
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confuses me as well. So, so, so that very, very nice.
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It's a fairly simple answer actually. And you'll kick
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yourself.
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So you say.
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You'll kick yourself. Because there is another force involved.
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So you've got gravity and yes. The L one sitting between the 2,
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1.5 million kilometers towards the sun from our own planet,
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which is that 1% of it is, it's 1% of the distance to the sub
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pretty well. Exactly. So that's easy to understand, but the
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others are totally counterintuitive, especially the
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ones that are outside the one that's outside the orbit of the
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Earth L Two.
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But the other force that comes into this is centrifugal force
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because the Earth is moving around the sun and 30 kilometers
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per second takes 365.25 days to go around. And that generates an
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outward force.
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Just as you know, spinning a, spinning a wheel, puts an
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outward force up and there, the balance between that and the
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gravity that it, it's a marvelous thing really. It's
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another of these wonderful natural phenomena that you don't
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expect, but the, the balance between centrifugal force and
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gravity gives you these 55 stable points which are very
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useful.
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So that's it, it's just centrifugal for us, someone's
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gonna, someone's gonna.
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Well, that's a question saying how, why I let me.
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Let me just elaborate a little bit further. So if you think of
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L Two, which is on the opposite side of the Earth from the sun,
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1.5 million kilometers away, The that's being pulled directly
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inwards by the gravity of the sun and the Earth.
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Yeah, because they're in a straight line. So the two of
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them are in a straight line, they're both pulling like mad
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with, with a giant gravity. But the centrifugal force is trying
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to push this anything at that point outwards, right?
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So, yeah, you've got a resistance.
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Gotcha.
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And for L Three as well. Even though that's on the other side
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of the solar system, it's still feeling the gravitational pull
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of both the Earth and the, and the sun.
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The other two, they're a bit, I, I actually find L Four And L
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Five, the hardest ones to understand intuitively which Jim
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was saying are the ones he can, he can, he can understand. Once
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because we've, we've got a, you know, we've got a sort of
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triangle, triangle of vectors. Basically, it's a pull by the
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Earth and by the by the sun forming a triangle like that.
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Here's the, here's the sun pulling, here's the Earth
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pulling. So you've got to point an object at the apex of the,
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the two vectors if I can use a technical term, the, the pool.
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But once again, that is balanced by the centrifugal force as
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these things troll around the Earth's orbit. So it is, it's
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very neat stuff invented by a mathematician who probably never
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thought we'd ever use it. For practical purposes.
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Was his name Lagrange.
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Very good.
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I think it's was it sid? No, it was Fred. Fred. Fred leg. Yeah,
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that's it.
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Of course. You know, all the caller greats are called Fred.
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Thanks. Thanks for the question, Jim. Our next question comes
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from Kerry. Hi, Andrew and Fred. Excellent podcast. Keep up the
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great work. The following has been nagging me for some time.
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How is the gravitational effect of supermassive black holes and
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dark matter on Galaxies?
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Separately determined if both are impacting a galaxy, how is
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the specific mass of a supermassive black supermassive
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black hole determined could an incorrect estimation of the mass
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of supermassive black holes be the cause of the need to include
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dark matter ie are the actual masses of supermassive black
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holes big enough to cause the gravitational effect that has
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prompted the need to include dark, the dark matter component.
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Looking forward to hearing your views and Kerry, thanks for
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putting supermassive black holes in the question four times.
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It's all right. You can get your tongue around that Andrew you.
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It is a great question. But the two are separate enough that
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they can be measured with pretty high precision separately. So if
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you've got a galaxy, you, you can with a supermassive black
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hole at its center. And if it, it works best for what we call
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active black holes, ones that are gobbling up their
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surroundings.
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So there's gas and dust which is whizzing around the black hole
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at relativistic speeds, speeds close to the speed of light and
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those speeds can be measured. And so you, what you can do is
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actually you can sense that very close to the black hole. There
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is a very high gravitational pull.
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And that's what that's what the speed of of rotation of the
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accretion disc tells you, it tells you that there's an
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enormous gravitational pull and that's really it, you know, it's
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far into the center of the supermassive black hole. And
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that phenomenon when you get, I don't know, even only 100 light
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years away on some supermassive black holes, it would be more
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than that, but you don't have to go far away before it
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disappears.
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So this is very much an effect due to the black hole itself.
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Whereas the effect on the galaxy and I, and if you take the
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simplest example, and we've got many, many observations of the
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different kinds that tell us that there is something missing
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there. That that dark matter is real.
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When you, when you look at the rotation of the whole galaxy,
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and you look at what would cause that the mass distribution that
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would cause that it's not concentrated at the middle. You
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can work out what the distribution of matter is by the
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rotation. And you find that it's a blob which is all around the
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galaxy, but it's quite separate from what the black hole
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measurements are a good question though. I like it.
00:08:56
Ok. Thank you, Kerry. I hope that helped. But yes, there,
00:09:00
there's obvious signs that differentiate them is what Fred
00:09:04
said, which would have been a shorter answer.
00:09:06
But we've got to stretch the program out some And yes, that
00:09:11
's, that's true actually.
00:09:12
Thank you, Kerry. Alright. Our next question which we, we had
00:09:16
to dump last week due to time constraints we're going to
00:09:19
tackle. Now. This is a, this is a what if question from Robert.
00:09:24
Hello Andrew.
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This is I would like the experiment for us. We made a
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connection with a very superior alien race, but because it's
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done through a super quantum computer, I ask one question.
00:09:38
You two gentlemen have been selected. So what will it be?
00:09:42
Can be the winning lottery number? You can ask anything
00:09:45
else is related. The dark energy Big Bang Cure for aging.
00:09:53
I'll just stop time travel back in time. Anything you like?
00:09:57
Please let me know and I'll be listening.
00:10:02
Ok, thank you, Robert. Only one question. Oh, look, I did some
00:10:05
research on this, Fred and I, I cos I, I couldn't think of a,
00:10:11
you know, an intelligent scientific question to ask. And,
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and I, I actually went to one of my favorite social media sites,
00:10:19
Reddit to see what people would say. Cos Reddit, Reddit people
00:10:23
are a little bit weird compared to other social media.
00:10:26
And I got a few ideas, but I, I do remember that the Harvard
00:10:31
Gazette did actually hone in on this via our good friend Avi
00:10:37
Loeb. And they made a point of saying, well, your first
00:10:41
stumbling block is going to be language, language is gonna be
00:10:45
the really, you know, the first major hurdle to overcome when it
00:10:49
comes to, speaking to another interstellar race.
00:10:54
And I don't know if you've seen the movie Arrival. A Arrival was
00:10:58
a, a film where these, creatures came to Earth in their
00:11:02
spaceships and sort of, you know, planted themselves all
00:11:04
over the world and they, they had to get, a linguist in to try
00:11:10
and decipher their language though.
00:11:12
We could find out what they wanted and of course, Earth,
00:11:14
being Earth, we went on ready alert and we're gonna blow them
00:11:16
all up. So there was a, there was a time limit on how this
00:11:20
would be resolved. It was very clever film and not only that,
00:11:24
it, it had a time element that completely confused me until the
00:11:29
very end and I went, 00, the story all weird.
00:11:33
But, yeah, that was, that's the first problem. I, I probably
00:11:38
wouldn't ask a scientific question straight up. I, I'd
00:11:41
leave that to the Fred Watsons of the world. I'd want to ask
00:11:45
them more rudimentary stuff. Like, you know, how, how do you
00:11:50
live day to day? What's your civilization like? Do you have
00:11:54
religion?
00:11:57
Do, do you, you know, live in houses and have streets and get
00:12:00
garbage collected? I, that's the stuff I'd wanna know. That's
00:12:03
exactly what goes through my brain. What is their lifestyle?
00:12:07
Not very scientific. But then again, I suppose that's.
00:12:10
Really important and, and yeah, it's the sort of thing you
00:12:14
should ask trouble is the answer you might get to a question like
00:12:19
that could be 42 because that's where the, where it goes a bit
00:12:26
wonky.
00:12:28
I'd like to, thanks. Sorry. Did I interrupt you there? No, no.
00:12:34
Ok.
00:12:37
Yeah, I mean, in, in, at some level I think we'd be asking the
00:12:43
same question but maybe framed in a different way. Because I
00:12:46
would like to know at the moment. Oh Let me step back a
00:12:51
bit at the moment.
00:12:52
Our best understanding of reality, the way the universe
00:12:56
works on big and small scales is the two theories, the two
00:13:00
pillars of our understanding of the universe general relativity
00:13:05
about things on big scales gravity and all that stuff,
00:13:08
Lagrange points, all of that general relativity and and
00:13:15
quantum mechanics, which is things being in two places at
00:13:19
once and curious things like that and things when you look at
00:13:23
one in one place, it, you immediately know what the other
00:13:26
one looks like in the other place.
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So those are, those are incompatible and a lot of
00:13:34
physicists in particular have suggested that there is a deeper
00:13:38
theory, some deeper theory that maybe quantum mechanics and
00:13:45
relativity emerge out of. And it could be, you know that there
00:13:51
are things that we simply don't understand at all. One is
00:13:53
gravity. We, we know the way it behaves because relativity tells
00:13:57
us that we have no idea what it is.
00:13:59
Yeah. So we possibly it might be gravitons but we haven't
00:14:01
discovered them yet. And the other one is time. We've got no
00:14:05
idea what time is. It's sort of, it's a, it's a unit in four
00:14:10
space time. You can see it in the equations, you find this
00:14:13
term which is C squared T squared coming up in these
00:14:17
equations. And that tells you that time is a dimension.
00:14:20
But beyond that, we really don't know much about it. And, and so
00:14:25
the thinking is that, that theory that underpins everything
00:14:31
might explain things like time, things like gravity, things like
00:14:36
why quantum mechanics is incompatible with general
00:14:38
relativity. And it might be, well, it might really be the
00:14:42
answer to life, the universe and everything it often called a
00:14:45
theory of everything we don't have it.
00:14:49
So your question would be, have you guys figured this stuff out?
00:14:54
But where it, where it where it overlaps what you said they
00:15:00
might say. Yeah. Yeah, we have actually we call it religion.
00:15:04
You know, it's, these are such deep questions, we really don't
00:15:09
know the answer to them. And so I think, I think there's a lot
00:15:14
of really pointed questions you could ask. Robert says, we can
00:15:17
only have one question since these two of us. That means we
00:15:20
can have two and they might.
00:15:23
And it's, it's very sad, Robert to have to admit that being
00:15:27
humans and we, we get this contact and we can ask one
00:15:31
question and the guy on Earth at the telescope who receives it
00:15:34
goes, can you hang on a second?
00:15:38
Too late? Done? Cos that's what had happened.
00:15:44
Yeah, I do agree with you. Arrival was a very good movie. I
00:15:47
really enjoyed science fiction movies irritate me enormously,
00:15:52
but that one didn't, it.
00:15:54
It's so deep, so deep, very cle, very cleverly constructed film.
00:16:00
And you've gotta concentrate. You can't go away and make a cup
00:16:03
of tea because you come back and go. What, what's happened.
00:16:07
What's happened? Andrew. I can never do that. I'm afraid I lose
00:16:10
the track of things so quickly. It takes about two milliseconds
00:16:13
and I've lost the track. So I've got to concentrate on
00:16:15
everything.
00:16:17
My, my wife and I'm talking quietly because she's just out
00:16:20
there. My wife will watch a half hour show after lunch and not
00:16:26
finish it for three or four hours because she keeps stopping
00:16:29
it to go and do little jobs around the house.
00:16:31
And that's, that's how she spends her afternoon. I'm gonna
00:16:35
watch a half hour show start at 12 and by the time I'm finished
00:16:39
doing these things around the house, it'll be four o'clock and
00:16:42
the show will be finished.
00:16:43
That's, I think there's a lot to be said for. That's, that's time
00:16:47
management, isn't it? Yeah, it's time management of the kind that
00:16:49
I simply don't know. I don't think you needed to lose your,
00:16:51
your voice though. I think that was a compliment. I hope you're
00:16:54
listening, Judy.
00:16:57
She didn't bang on the door. So I'm sorry.
00:17:01
Look, I, I could go on with, with ideas about this question
00:17:04
from Robert for forever. There is, you know, the questions just
00:17:09
keep coming to mind and you could ask squillion of questions
00:17:12
and still not scratch the surface about anything really.
00:17:16
But it is a great question and, and one we might get to tackle
00:17:19
again further down the track, the older and wiser. Robert,
00:17:23
thank you very much for the question.
00:17:25
Don't forget if you have a question, send it in to us
00:17:27
whether it's by audio or text through our website, Space Nuts,
00:17:31
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00:17:58
are patrons that put a little bit of money into the place to
00:18:01
keep the lights on. And you know, pay Hugh's enormous
00:18:06
salary. And, and Fred that brings us to the end of yet
00:18:12
another show. Thank you very, very much.
00:18:14
It's a pleasure. I think it might have brained up my health
00:18:17
a bit.
00:18:19
I think the very often that's all you need is get out of your
00:18:22
minds, get out of your misery and.
00:18:25
Yeah, a keep yourself occupied and you feel a lot better. Very
00:18:29
true. Thanks, Fred. We'll catch you next week.
00:18:32
And thanks to Hugh in the studio for reasons that don't come to
00:18:37
mind, but I'm going to get the telescope out and ask an alien
00:18:40
what Hugh does. And until next week, looking forward to your
00:18:44
company on the next episode of Space Nuts.
00:18:47
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