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Cosmic Conundrums: Time Dilation, Dark Matter & the Quest for Faster-Than-Light Travel · Space Nuts: Astronomy Insights & Cosmic Discoveries

0:00
Heidi Campo: Welcome back to another episode of space
0:03
nuts.
0:03
Voice Over Guy: 15 seconds. Guidance is internal.
0:06
10, 9. Ignition
0:09
sequence start. Space nuts. 5, 4, 3,
0:12
2. 1, 2, 3, 4, 5, 5, 4,
0:14
3, 2, 1. Space nuts. Astronauts
0:17
report. It feels good.
0:19
Heidi Campo: I'm your host for this summer, filling in
0:22
for Andrew Dunkley. My name is Heidi Campo.
0:25
And joining us is professor Fred Watson,
0:28
astronomer at large.
0:30
Professor Fred Watson: Uh, good to be here, Heidi, as always. And
0:32
you're also our host for this winter here in
0:35
Australia. So, yeah,
0:38
lovely to talk. And um, I think we've got
0:40
some pretty great questions from our, uh,
0:42
listeners for this episode.
0:44
Heidi Campo: We do. We have some really fun, uh,
0:48
uh, not episodes. We have some fun questions.
0:51
Um, our first question today is
0:54
Martins from Latvia. And here
0:57
is his question.
0:59
Martins: Hello guys. It's, uh, Martins from
1:02
Latvia. Um, I've been loving your show. Been
1:05
listening since 2017. And, um,
1:09
so I have a question about dark matter.
1:12
Okay, just kidding. I have a question about
1:14
speed, uh, of light. So we have two objects.
1:17
One object is on Earth and the other one is
1:20
traveling in space at the speed of light.
1:23
After some time it comes back and the object
1:25
that's on Earth is older than the other
1:28
object. So why is that happening
1:31
again? Why? They aren't the same, uh,
1:34
age. I mean. Yeah, there's something to do
1:36
probably when you're reaching speed of light
1:38
that time is slowing down or something. But
1:40
why it's slowing down? Why isn't it, uh,
1:43
like. Yeah, just curious.
1:46
And uh. Yeah, and I have,
1:48
um, some dad joke for your,
1:51
uh, arsenal, Andrew. So, uh,
1:54
how do you put a space baby to sleep?
1:57
You rock it. So anyways, guys,
2:01
cheers then. Yeah, have a good one.
2:04
Heidi Campo: Well, I think those space babies will
2:07
being well with those jokes. Thank you so
2:09
much, Martinez. That's a. That was a good
2:11
one.
2:13
Professor Fred Watson: Yep. Space babies, uh, always need to be
2:16
rocked. That's right.
2:19
So, uh, now that's a great question.
2:22
Um, um, I have visited Latvia actually.
2:25
Uh, some years ago we did a tour there. I do
2:28
remember, um, you know, Heidi, because we've
2:31
talked about it before. I'm very fond of
2:33
trains. We traveled on a little railway,
2:35
uh, through the snow and through, uh. Because
2:38
we always visit these places in winter, uh,
2:40
through snow and woodlands. And it trundled
2:43
along at something like
2:46
nine miles an hour. Maybe it
2:49
was a fast walking pace
2:52
because it was a very old line, but it was a
2:54
lot of fun. Anyway, enough about Latvia.
2:56
Uh, let's get to the speed of light, which is
2:59
basically what Martin's question is about.
3:02
Um, this is, it's one of the
3:05
fundamental aspects of
3:07
relativity. Uh, Einstein's two theories
3:10
of relativity. One was about motion. The
3:12
other was about gravity. It's the one about
3:14
motion that covers this. That's called the
3:16
special theory of relativity. Uh, dated
3:19
1905. And it turns out
3:21
that the thinking that Einstein had had,
3:25
uh, leading up to this. Was
3:27
that we know that the speed of light
3:30
is a bizarre quantity.
3:33
Because in a vacuum it's always the same.
3:36
We know also that it's the maximum
3:39
speed that anything can attain. In fact, you
3:41
can't actually achieve the speed of light
3:43
with an object. Because you would have to put
3:46
infinite energy in to get it to the speed of
3:48
light. And we don't have infin infinite
3:49
energy. So light and its other
3:52
electromagnetic waves. They are the only
3:54
things that can travel at the speed of light.
3:57
But if you had something that you are
4:00
accelerating. Well, let me just go back. The
4:02
speed of light is almost like a
4:05
magic number. It's not magic because it's a
4:07
very round number. It's about 300,000
4:09
kilometers per second. Uh uh,
4:12
it is, however, the fact that it
4:15
doesn't change in a vacuum. And it doesn't
4:17
matter how fast the source is moving. You'd
4:20
expect if you have a source that's moving.
4:22
That sends out a beam of light. Um,
4:25
the source's speed would add to the speed of
4:28
light. And the speed of light would increase.
4:29
But it doesn't doesn't work like that. And
4:32
once you establish that, then it
4:34
turns out. And there's some
4:37
quite sort of simple ways of
4:40
seeing how this might work. Which we don't
4:43
really have time to talk about. But some of
4:44
the books about special relativity. That talk
4:47
about people looking at somebody moving on a
4:49
train. Show you how the geometry works. That,
4:52
uh. Because the speed of light is always the
4:55
same. Then what it tells you is
4:58
perceptions of time and distance must change.
5:01
And so the key thing here. And the point
5:04
that, uh, Martins is raising.
5:07
Is that if you've got an observer
5:10
who is stationary. Compared with somebody
5:13
who's moving at a very high speed. Nearly,
5:16
uh, the speed of light or yeah.
5:19
It doesn't matter whether it's near the speed
5:20
of light or not. The effect works. But it's
5:23
when you get nearer the speed of light. That
5:25
it becomes noticeable. Um, the
5:27
time that you observe. Um, that
5:30
moving person,
5:33
uh, experiencing is slower. So your
5:36
time's ticking away as normal. And
5:39
the person who's moving past you. Their time
5:42
is ticking away as normal. But when the
5:44
stationary person if you could see the clock
5:48
on the moving vehicle or whatever it is.
5:50
Train Going at nearly the speed of light.
5:52
Just to mix a few metaphors there, um, what
5:54
you would see is their clocks would seem to
5:56
be going much more slowly than yours is.
5:59
And that's the time dilation effect.
6:02
And yes, it means that, um, if you
6:05
can then bring these two back together, the
6:08
moving person has experienced less
6:10
time relative to you than you have. And
6:13
that's the. It's sometimes called the twins
6:16
paradox. Because if you take two twins, one
6:19
goes off at the speed of light, comes back
6:20
again, or nearly the speed of light, comes
6:23
back again there they have aged much less
6:25
than the twin who stayed put.
6:30
So that's the bottom line. And
6:35
it's such a counterintuitive concept that it
6:38
is really hard to get your head around. But
6:40
we know it works. Uh, in fact,
6:43
um, the demonstration, um, the practical
6:45
demonstration of this phenomenon happening in
6:48
reality, uh, I think it was just before the
6:50
Second World War. Might have been round about
6:53
the same time. But there are things called
6:55
cosmic rays which are bombarding the Earth
6:57
all the time. These are subatomic particles
6:58
that come from space. Um, and they
7:01
are predominantly a
7:04
species of subatomic particle called a muon.
7:07
So these muons were observed coming down
7:10
through space at, uh, nearly the speed of
7:12
light. And we know how long
7:15
they take to decay in the laboratory.
7:18
But their decay time was much longer
7:21
when they were observed coming in at the
7:23
speed of light, nearly the speed of light,
7:26
the time had dilated. So the decays were much
7:28
longer than what we observe in the laboratory
7:30
when they're not stationary, but they're
7:33
going much more slowly. So it is a proven
7:36
fact this works. Uh, if we could
7:39
build a spacecraft that would get us to. I
7:42
can't remember what it is. I think it's
7:43
99.99998% of the speed
7:46
of light. Head off for 500
7:49
light years, come back again. Uh, you will be
7:52
10 years older, whereas everybody else on
7:55
Earth will be a thousand years older. So
7:57
it's that sort of thing. Your time has slowed
8:00
down relative to what they've experienced.
8:05
Heidi Campo: I had a weird nightmare about that the other
8:06
night.
8:07
Professor Fred Watson: Oh, did you?
8:08
Heidi Campo: It was the strangest thing. I had a nightma.
8:10
Um, somebody put me in, like, some kind of a
8:13
cryo sleep. And I woke up and so much time
8:15
had passed that everyone I knew had died. And
8:17
so I had them put me back in cryo sleep for
8:20
thousands of more years until we discovered
8:22
the technology to travel back in time so I
8:24
could go back in time and link back up with
8:26
everyone I loved.
8:30
Professor Fred Watson: That's A pretty good one is that.
8:32
Heidi Campo: I have a very active dreamscape. Uh,
8:35
at night I wake up exhausted.
8:38
Professor Fred Watson: Okay.
8:39
Heidi Campo: All right.
8:40
Well, our next, uh, question has a little bit
8:42
of philosophy in it. Um, this, this question
8:44
is coming from Art from Rochester, New
8:47
York. And it's, ah, it's quite a long
8:49
question. So let's, uh, grab a cup of tea
8:52
here. Art
8:55
says, I was listening to the June 13 program
8:57
concerning the flying banana, which prompted
9:00
me to submit my first question to Space Nuts.
9:03
It is a question I had been pondering for
9:05
some time. You will be glad to hear it is not
9:08
a black hole question, but rather a what if
9:10
question. The great American philosopher
9:13
Julius Henry Marx once postulated,
9:16
time flies like an arrow, fruit flies like a
9:19
banana. Based on
9:21
empirical evidence, I can confirm that fruit
9:24
flies like a banana. My question
9:26
revolves around time flying like an arrow.
9:30
To the best of my understanding, when we
9:32
shoot off rockets to the moon or Pluto,
9:34
in order to get there accurately, the rocket
9:37
scientists use an
9:40
amphimerus. M. You'll have to correct me on
9:42
the pronunciations of that or possible
9:45
amphimerds as a sort of a map.
9:48
If faster than light space travel were
9:50
possible, how could one navigate from point A
9:53
to point B? Is it possible to develop
9:56
an ephemeris for faster
9:59
than light travel? Thank you, Art from
10:01
Rochester, New York.
10:04
Professor Fred Watson: A great question, Art. And, uh, yeah,
10:07
your pronunciation is correct. Ephemeris is
10:10
what these things are, and ephemerides is
10:12
what a lot of them, ah, are. So what's an
10:14
ephemeris? Well, uh, the
10:17
original meaning, um, and I
10:20
guess this really is still the meaning of the
10:22
word is, uh, to predict
10:25
where, uh, planets are going to
10:28
be, uh, in the future, where
10:31
celestial objects are going to be. So,
10:33
um, going back to my master's
10:36
degree, uh, back, you know,
10:38
150 years ago, my work was on,
10:42
um, the orbits of asteroids. And
10:45
so there were two problems. First problem was
10:48
how do you take observations of an asteroid?
10:50
And remember, all we had in those days was
10:53
the direction that you could see measured
10:55
with a telescope. How do you turn that into
10:57
knowledge of the orbit of the
11:00
asteroid, uh, in three dimensions? And you
11:02
can do it. You need at least three
11:04
observations to do that, but you can do it.
11:06
You can mathematically deduce the orbit from
11:08
just three directions in space. But then once
11:11
you've got the orbit, what you want to know
11:13
is where it's going to be in the future,
11:15
what's its direction in space going to be?
11:17
And that is what an ephemeris is. It's how
11:21
the position of an object changes, uh, in the
11:23
sky, uh, over time. Um, so
11:26
it comes from the word ephemeral, meaning
11:29
stuff that's temporary. Uh, so an
11:31
ephemeris, uh, is the,
11:34
basically it's a table of where an object
11:37
will be over a given amount of time. And of
11:39
course it's critically important these days
11:42
because we now know that, which we didn't
11:44
know when I did my master's degree. We now
11:47
know that the Earth's locality is pretty
11:49
heavily populated with asteroids. And
11:51
there's, you know, we might want to know
11:53
where they are just in case one's uh, heading
11:56
our way. So um, I, you know, I think the
11:59
question, Art's uh, question is uh, a good
12:02
one in the sense that, okay, he's saying,
12:05
yes, we, we use ephemera, um,
12:07
ephemerities to, to basically
12:10
navigate to objects.
12:13
Um, it's actually a little bit more
12:16
than that because we, we use effectively
12:19
a three dimensional map of where these, these
12:21
planets are, uh, in order to
12:25
dictate where they're going to be when your
12:27
rocket arrives there. And that's critically
12:28
important of course, because you want the
12:31
rocket to get to the orbit of for example
12:33
Pluto, as Art mentions, uh,
12:36
when Pluto is going to be where, whereabouts
12:39
the rocket is. You don't want to reach the
12:41
orbit of Pluto and find Pluto somewhere else.
12:43
That's why you need uh, an ephemeris.
12:46
But uh, if you could travel faster than the
12:49
speed of light, and we've already shown that
12:51
that's impossible, uh, in this episode
12:54
because you need infinite energy to do that,
12:56
uh, to reach the speed of light. But if you
12:59
could, um, the ephemeris would still
13:02
work. Um, you would need to put
13:05
in a negative number for the.
13:09
I think the speed of light
13:12
actually goes into ephemeris calculations. I
13:14
remember it well. But I think you
13:17
uh, put in a factor. It wouldn't be a
13:19
negative number. It would be a factor that
13:21
would allow for the fact that you were
13:22
traveling at faster than the speed of light.
13:24
So you could do it. It's not an impossible
13:27
mathematical problem.
13:31
For what it's worth.
13:33
Heidi Campo: Well that was fantastic. Uh, I just about
13:35
understood that too.
13:38
Professor Fred Watson: Sorry.
13:39
Heidi Campo: Uh, no, you always do such a great job of
13:41
explaining these. Um, my IQ is going
13:43
up every time I'm um, involved on these, uh,
13:46
these episodes. And also great questions.
13:49
We have some of the smartest, smartest
13:52
listeners. I mean these people are, are
13:54
brilliant.
13:59
Speaker C: Space nuts.
14:01
Heidi Campo: Um, our next question is another audio
14:03
question, um, from David from Munich.
14:06
And it's a little bit of a longer question as
14:08
well. So, so we are going to go ahead and
14:11
play that for you now.
14:13
Speaker C: Hey guys, David from Unique here. Uh,
14:16
shout out to Andrew, Fred and
14:19
Jonti and I heard that you're a bit
14:22
shorter in questions so I thought that's my
14:24
chance to submit one.
14:27
I'm currently looking at the picture from um,
14:29
or taken by the James Webb Telescope. You
14:32
know the first one, the first um, deep space
14:34
which was also presented by President Biden
14:36
back then. And I realized that the
14:39
galaxies do differ in
14:42
their color pretty much. So there are
14:44
more white ones, uh, orange ones and also
14:47
reddish ones. And I um, wonder
14:50
how is that, Is it due to the fact that
14:54
um. Or is this like the red shift because
14:56
they're moving away, which I
14:59
kind of doubt, but I don't know what, what is
15:02
it else? Or is there so much material of a
15:04
different, of different kind
15:07
in the galaxy that appears for us more
15:10
red or more blue. So
15:13
would be nice if you could explain that.
15:16
And um, also I wonder a bit.
15:18
Let's imagine we would travel to this far
15:21
distant galaxies. Um, if we
15:24
could do it potentially
15:27
would it not be some kind of
15:30
travel through the time?
15:33
So because when we look back there, right. We
15:35
see them on their early stages. So
15:38
till it's a long time until
15:41
um, until the light reaches us. And if you
15:44
would travel to that far distant uh,
15:46
galaxies you would basically.
15:49
Or what I imagine is like you would travel
15:51
through time, right. So if you did, the
15:53
moment you come closer and closer the galaxy
15:56
or maybe let's think of a single planet would
15:59
then change its appearance, right? So you
16:02
would see that it's alter, uh, it shifts
16:05
maybe its base or it merges with another
16:07
galaxy. Um,
16:09
is my thinking correct, Would it like the
16:12
far. The closer you come the more it would
16:15
change its shape and it, I
16:18
don't know, colors maybe.
16:20
Um, and things you would see.
16:23
Um. Yes, thanks for taking my questions. Um,
16:26
like the shop and, and um,
16:29
till then.
16:30
Heidi Campo: Well, thank you so much. Um,
16:33
that was David from Munich. Thank you. That
16:35
was a well thought out question. Fred, I'm so
16:38
curious.
16:39
Professor Fred Watson: They were great questions Heidi from
16:42
David and in fact the answer to both his
16:44
questions is yes. Um,
16:47
so David's asking whether
16:50
the color changes that we see in the
16:52
images, uh, of these deep fields as we
16:55
call them, uh, looking way back in
16:58
time, uh, whether those different colors of
17:01
galaxies is caused by
17:04
the different redshifts of these galaxies.
17:07
And that's the bottom line. But there's a few
17:09
caveats here. Let me just explain what I
17:12
Mean, um, redshift is the
17:14
phenomenon that, uh, as light travels
17:17
through an expanding universe, uh, the
17:20
universe is expanding, light is making its
17:22
way through the universe, but as it goes, the
17:24
universe is getting bigger. And so the
17:26
light's wavelength is actually being
17:28
stretched. Uh, and, uh, as you
17:31
stretch the wavelength of light, it goes
17:33
redder. It goes to the redder end of the
17:34
spectrum. And so that's what's happening. But
17:37
the caveat that I mentioned is that these are
17:40
actually false colors in the sense that the
17:43
James Webb telescope is an infrared
17:45
telescope. So it is looking at light that our
17:47
eyes are not sensitive to. It's actually
17:49
redder than red light that it's looking at.
17:52
So what the mission scientists do
17:55
is they, um, they take
17:58
the shortest wavelengths that the Web
18:01
can see, which are really beyond
18:04
our. They're redder than red for us,
18:07
for our eyes, but they're the shortest
18:09
wavelengths that the red can detect, and they
18:11
make that blue in their colors. And then the
18:14
longest wavelengths that the Web can detect,
18:16
they make it red in their colors and that. So
18:19
that mimics what we would see with
18:22
our eyes, uh, with visible, you know,
18:24
visible light, but it mimics it moved into
18:27
the infrared. So it does mean that as
18:30
objects, uh, you know, get
18:32
redder, uh, in the infrared spectrum, we see
18:35
them redder, uh, in the James Webb telescope
18:37
images. And that's exactly the reason
18:40
the most distant objects are so highly
18:43
redshifted, that you're seeing them as red
18:45
objects compared with the white objects,
18:47
which are the much nearer ones. So David's
18:50
right on that front. His second question,
18:53
uh, what would some of these galaxies we're
18:55
looking back, you know, up to. I think the
18:57
record is looking back 13.52 billion years at
19:00
the moment, which is 280 million
19:03
years after the birth of the universe. It's a
19:06
big puzzle as to how galaxies got
19:09
so big and so rich,
19:12
um, in that short period of time. But that's
19:15
for the cosmologists, not for us. Um,
19:18
they'll work it out. It'll be okay. Uh, the
19:20
bottom line, though, is that if you could
19:23
forget about the journey, because we can't
19:25
travel the sort of speeds that you need. But
19:27
if you imagined yourself, uh,
19:30
instantly transported from
19:33
our, uh, vantage point here on Earth to
19:36
one of These early galaxies, 13.52
19:38
billion years, billion light years away, what
19:41
you would see would be a galaxy that might
19:43
look a lot like ours. It has evolved
19:47
because you're seeing it. I mean, you've got
19:48
to imagine we're being
19:51
transported instantaneously. So that what we
19:54
see is what's happening now. That galaxy will
19:56
have had 13.52 billion years of evolution.
19:59
It'll be quite different. It might actually
20:01
be quite a boring galaxy compared with the
20:04
very, uh, energetic, uh, infant galaxy that
20:07
we look at with the James Webb telescope.
20:09
Complicated answer to a simple question, but
20:12
David's right on the money.
20:14
Heidi Campo: That is such an interesting way of thinking
20:16
about that. I, um, I'm going to be
20:18
spending, I'm going to be spending a while
20:21
wrapping my head around that one.
20:25
Professor Fred Watson: Okay, we checked all four systems and seeing
20:27
where to go space nets.
20:29
Heidi Campo: Um, our last, our last question of the
20:31
evening is from Daryl Parker of
20:34
South Australia. Daryl says,
20:37
G' day, space nuts. I'm not sure of
20:40
the best way to ask this question, so I'll
20:42
just ask it the best way I can. That's
20:45
usually, that's usually the, the best way.
20:48
Uh, do objects, meteors, asteroids,
20:51
comets, planets, stars,
20:53
solar systems and galaxies
20:56
produce heat as they move through space? Is
20:59
it friction or is friction a thing
21:02
in the vacuum of speed and the vacuum of
21:05
space? Thank you in advance. And that's
21:07
Daryl from South Australia.
21:10
Professor Fred Watson: Uh, another great question. Um,
21:13
so if space was a complete
21:16
vacuum, and as I'll explain in a minute, it's
21:19
not quite. But if it was a perfect vacuum
21:22
with nothing in there, then, uh,
21:25
there would be no friction,
21:29
uh, as Daryl's calling, um,
21:32
would be, uh, uh, you know,
21:35
there'd be nothing to, uh, to limit the
21:38
speed of motion, uh, of an object moving
21:40
through it. And it wouldn't get hot. There
21:42
would be no friction to heat it. And
21:45
I think the way Daryl's thinking here, and
21:47
it's quite right to, uh. When a spacecraft
21:49
enters the Earth's atmosphere, uh, it's the
21:51
friction between the spacecraft itself moving
21:54
against the air molecules that causes it to
21:56
be heated and gives us this heat of reentry.
21:58
There are a few subtleties to that, but
22:00
that's basically the way it works. So things
22:02
moving through an atmosphere get hot. Um,
22:05
now, uh, space
22:08
beyond the Earth's, uh,
22:11
atmosphere is not a vacuum.
22:13
It's very nearly a vacuum. And that's why you
22:16
can put a satellite up and it'll stay up for
22:18
200 years or whatever. And it's why, you
22:21
know, the Moon doesn't come crashing down to
22:22
Earth. In fact, the moon's going the other
22:24
way. It's moving away from the Earth very
22:26
slowly, but the, um,
22:30
it's nearly a vacuum, but it's not quite
22:33
so. Uh, there is basically, um,
22:37
a very, very slight braking effect,
22:40
uh, which in the Earth's vicinity, the
22:43
Earth's atmosphere doesn't just stop, it sort
22:45
of fades away. So even
22:47
10,000 kilometers away, there's still a
22:50
little bit of residual atmosphere, which
22:51
would have a slowing effect on a spacecraft.
22:54
When you get into interplanetary space,
22:57
there's a lot of dust and there's, there's
23:00
also subatomic particles there. When you get
23:03
to interstellar space, the space between the
23:05
stars, there is something that we call the
23:07
interstellar medium, uh, which is
23:09
basically the radiation and
23:12
particle environment of interstellar space.
23:15
There are subatomic particles all through
23:17
space. Now there, it's still so much of
23:20
a vacuum that there's nothing really to heat
23:23
a spacecraft. So Voyager, as it ventures
23:25
through interstellar space, is on the brink
23:28
of interstellar space. Now that, uh, won't
23:30
get hot because of that, um, because the
23:33
friction is far too small. But when you do
23:36
see its effects, uh, they are on
23:39
very big scales. And we do see,
23:41
uh, when we look at some objects
23:44
deep in space, for example in a gas cloud,
23:47
uh, a nebula, where, um,
23:50
maybe there are stars forming, sometimes you
23:52
see objects which are moving through that gas
23:54
cloud. And what you can see is a shock wave,
23:57
uh, being generated. And sometimes
24:00
that causes star formation, that shockwave of
24:03
the gas cloud. Um, now, yes, that's
24:06
Jordy agreeing with me there. Uh, he's
24:09
just come back from his walk, so he's very
24:11
enthusiastic about this idea. Uh, he's
24:14
probably seen a shockwave. Um, and a
24:16
shockwave is what you get when something
24:18
moves rapidly through the atmosphere. You
24:20
know, that's what causes the sonic boom of a
24:22
supersonic jet. Um, so
24:25
with very big objects in gas
24:27
clouds in space, then you do get that sort of
24:30
effect. The interaction between the moving
24:32
object and its surroundings generates a
24:35
shockwave and would generate heat as well. So
24:37
under certain circumstances the answer is
24:39
yes, Darrell, but probably for most things
24:41
it's no.
24:44
Heidi Campo: So.
24:45
So, Fred, I don't know if you'd have time for
24:47
a follow up question of my
24:50
own. Yes, um, so
24:53
I guess I never really thought of, um, the
24:56
gravity atmosphere around planets having
24:59
different layers. It's like, I knew there was
25:01
layers, but it's like to really think, okay,
25:02
you know, it gets thinner and thinner and
25:04
thinner, but there's still particles, uh,
25:06
being pulled into that atmosphere. But it
25:08
just, it spreads out quite a ways well
25:11
beyond our atmosphere. Are there points of
25:13
space, and you may have already mentioned
25:15
this, but are there points of space where
25:16
there's particles floating around that are
25:18
not being affected by any gravity at all? Or
25:21
is every part of space affected
25:24
by something's gravity?
25:26
Professor Fred Watson: Um, yeah, pretty well. Um, the thing about
25:29
gravity is it, it goes on for
25:32
infinity. Um, it's, ah, it's a
25:35
bit like actually light is the same.
25:36
Electromagnetic radiation will not stop. It
25:39
just keeps going until it gets too weak
25:42
to be detected. You're talking about a
25:43
dribble of, you know, hardly any photons.
25:46
Gravity is the same. We don't know whether
25:49
gravity has a subatomic particle equivalent.
25:51
We think it might have, and we call them
25:53
gravitons, but they haven't been discovered
25:54
yet. But yes, uh, that's actually,
25:57
you know, it's why, uh, an object
26:00
like Pluto, way out there in the depths of
26:03
the solar system, is still in orbit around
26:05
the sun, even though it's all these, what is
26:08
it, five, six billion kilometers away.
26:11
Um, the gravity of the sun is still
26:14
a force because gravity goes on
26:17
forever. Uh, but of course, when
26:20
you get way out into interstellar space,
26:23
then you might feel the sun's gravity, but
26:25
you'd also feel the gravity of other stars.
26:28
Uh, and so I think you're right that there is
26:31
always going to be a sort of gravity
26:32
background, uh, because of the
26:35
objects which are in the universe. Maybe
26:38
it's pretty near zero in the space between
26:40
galaxies, uh, which is pretty empty, although
26:43
there are subatomic particles there too. Uh,
26:46
but, uh, yeah, but no, it's a. It's a very,
26:49
um, A very compelling force is
26:51
gravity, which is just as well because
26:53
otherwise we wouldn't exist.
26:56
Heidi Campo: There's always something pulling. It's just
26:59
going to be stronger or weaker. No matter if
27:01
it's. No matter if it's the biggest gap in
27:05
the known cosmos,
27:08
there's still a little thread pulling us
27:10
together. Oh, that's so beautiful. That's
27:12
kind of cool. We're all connected somehow.
27:14
Professor Fred Watson: That's a connection. That's right. Yeah.
27:17
Heidi Campo: Um, Fred. Well, this has been a
27:20
very enlightening Q and A episode
27:23
of Space Nuts. Thank you so much for
27:26
sharing your wealth of knowledge with us.
27:29
Um, while your rooster. I'm sorry, your dog.
27:32
Sings his song in the background.
27:35
Professor Fred Watson: That's what he sounds like. I know. Um, his
27:38
voice hasn't broken yet.
27:41
Heidi Campo: It's kind of cute. It's endearing. Um, thank
27:43
you so much.
27:44
Professor Fred Watson: This has been, been.
27:44
Heidi Campo: This has been fantastic. And, um, we
27:47
will, we will, I guess, catch you guys next
27:50
time. Please keep sending in your amazing
27:53
questions. And, um, real quick, before
27:55
we go, we are going to play a, uh,
27:58
another, um, another
28:01
update for you. So this is your little Treat
28:03
for listening to the whole thing. We've got
28:05
an update from Andrew, your beloved
28:08
regular host. I know you guys probably miss
28:10
him because your questions are still
28:12
addressed to him, but, um, he's on his trip
28:15
around the world. Going to let that, um,
28:18
play back now.
28:19
Andrew Dunkley: Hi, Fred, hi, Heidi, and hello, Huw
28:22
in the studio.
28:23
Andrew back again, reporting from the Crown
28:26
Princess on our world tour. Uh, since I spoke
28:28
to you last, our, uh, cruise has made news
28:31
all over Australia. You might have seen some
28:33
of the reports or heard some of the news
28:35
about some of the conditions we've had to
28:38
deal with. When I last spoke to you, I was
28:40
explaining how we were heading into rough
28:42
weather. We got off to a pretty rocky start.
28:45
Well, it got much, much worse. We
28:48
were having lunch in one of the restaurants
28:50
at the back of the ship and we got hit by
28:53
a weather front. It felt like we'd been
28:56
rammed and the. The ship tilted
28:58
over 7 degrees and it stayed there for the
29:01
rest of the day. It just hit us out of
29:04
nowhere. The captain had to do some heavy
29:06
maneuvering to get us, uh, into. Into a, you
29:09
know, better position. And they had to move,
29:12
um, the ballast to, uh, keep the
29:14
ship, uh, balanced and upright as
29:17
much as they could. Uh, yeah, it was pretty
29:20
harrowing. And the weather never got better,
29:23
uh, until we got into Adelaide and were in
29:26
protected waters. But, um, the Adelaide was
29:28
fantastic. Went to, uh, Handorf, as I
29:31
mentioned, that little German village where
29:33
the German people. People came in all those
29:35
years ago. They were, um, they were basically
29:38
escaping, uh, Prussian oppression when they
29:40
came out here in the 1800s. And, um, yeah,
29:43
made it, made a German town, which is
29:44
fantastic. Had, uh, a good look around
29:47
Adelaide, although the weather was terrible.
29:48
We went to Mount Lofty, which is one of the
29:50
best views in Australia. And all we saw was
29:52
cloud and very strong winds. It
29:55
was, uh, it was quite nasty. Got
29:58
back on board, uh, we had to stay the night
30:00
in Adelaide because of the conditions, hoping
30:02
they'd settle down. And we did have some good
30:04
sailing until we got to the West
30:07
Australian border and then another weather
30:09
front hit us and it got rough again
30:13
and. Yeah, gosh. And just to top it all
30:16
off, we had a galley fire in the middle of
30:18
the night at one point, which they dealt with
30:20
very, very quickly. So it's been a bit of a
30:23
dog's, uh, breakfast of a cruise in some
30:25
respects, but we're still having a fantastic
30:27
time. We stopped at Fremantle again,
30:30
um, because of the weather. We were very late
30:32
and so we stayed the night. We have friends
30:34
in Fremantle so We spent the evening with
30:36
them. It was fantastic. And we set
30:39
sail again yesterday, headed west. We
30:42
leave Australia now, headed for Mauritius.
30:44
That'll be a seven day crossing of the Indian
30:47
Ocean. So that's where things are at with
30:49
our uh, current tour. Um,
30:52
we're really enjoying ourselves. I must
30:55
confess. The crew here is fantastic.
30:58
And uh, you know, with over 2,000 Aussies on
31:01
board, we outnumber everybody about 10 to 1.
31:03
Which is, which is good. But so many
31:06
nationalities. Hope all is well back home and
31:09
in Houston of course. Heidi, look forward to
31:11
talking to you next time. Uh, no, Aurora.
31:13
Heidi Campo: Australa.
31:13
Andrew Dunkley: Australis. Missed out completely. Couldn't
31:15
see that. So um, hopefully when we get up
31:18
north we'll see the other end of the uh,
31:20
country and ah, see if there's any lights up
31:23
there. North. So until next time, Andrew
31:25
Dunkley signing off.
31:27
Voice Over Guy: You've been listening to the Space Nuts.
31:30
Podcast available at
31:33
Apple Podcasts, Spotify,
31:35
iHeartRadio or your favorite podcast
31:38
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31:39
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31:42
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bitesz.com
31:47
Heidi Campo: See you later, Fred.
31:48
Professor Fred Watson: Sounds great.