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Spaghettification Mysteries, Neutron Stars vs. Black Holes & The Wormhole Debate · Space Nuts: Astronomy Insights & Cosmic Discoveries

0:00
Andrew Dunkley: Hi again, Andrew Dunkley here. And, uh,
0:03
thanks for joining us, uh, on Space Nuts Q
0:06
and A edition. And coming up, we've got
0:08
questions from Buddy about spaghettification,
0:11
and I'm pretty sure he's not talking about an
0:13
Italian restaurant. Uh, we're also looking at
0:16
news. Neutron stars versus black holes. I
0:18
think we've had similar questions in the
0:20
past, but it keeps coming up. Uh, we're
0:23
also looking at wormholes. And,
0:27
uh, somebody has a pre Big Bang
0:29
theory which we'd like to discuss. We'll talk
0:32
about all of that on this episode of Space
0:35
Nuts. 15 seconds.
0:36
Generic: Guidance is internal. 10,
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9. Ignition sequence start.
0:42
Jonti Horner: Space Nuts. 5, 4, 3, 2.
0:44
Generic: 1, 2, 3, 4, 5, 5, 4, 3,
0:47
2, 1.
0:48
Jonti Horner: Space Nuts astronauts report it feels
0:50
good.
0:51
Andrew Dunkley: And I do love the Q and A edition because,
0:54
um, somebody else other than us sets the
0:56
agenda. The downside is we have to think.
0:59
And joining me now is Jonti, uh, Horner,
1:02
professor of Astrophysics at the University
1:03
of Southern Queensland. Jonti, hello again.
1:06
Jonti Horner: Hello again. Good afternoon. Good evening.
1:09
Andrew Dunkley: Good to see you. Got, um, some interesting
1:11
questions today. Do you want to get straight
1:13
into it?
1:13
Jonti Horner: Yes, can do. And I will give the usual caveat
1:16
right at the start of this. I'm quite happy
1:17
to admit my ignorance to a lot of this. Um, I
1:20
am not a cosmologist, so this is pushing
1:23
the boundaries of my knowledge to places that
1:25
it has never gone m before. And I'll do my
1:27
very best, but my apologies, other answers
1:30
are available. And you know, there's a film
1:32
critic in the UK who often says other
1:34
opinions are available. They're wrong, but
1:35
they're available. Um, in the case of this
1:38
one, it may well be that other answers are
1:40
available and they are more likely to be
1:42
right than mine. But I will do my best.
1:44
Andrew Dunkley: Fred often throws in the same caveat, so it's
1:46
all good.
1:47
Uh, our first question today comes from a
1:50
regular contributor. His name is Buddy.
1:53
Generic: Hello, space. This is Buddy from Ontario,
1:56
Oregon. Hey, um, I got a
1:59
question about spaghettification. Is it an
2:02
illusion or is it a. Is it real?
2:05
Is it. Is it just, uh, a distortion of
2:08
our eyes to the fourth dimension? Or are
2:10
things actually being stretched? And
2:13
on that same page, they say that photons
2:16
and photonic particles act like a wave and a,
2:19
uh, particle at the same time. Is that what
2:21
makes it a wave? Maybe. Is that a form of
2:23
spaghettification? Maybe. All
2:26
right, thanks, guys. Love your podcast.
2:29
Andrew Dunkley: Thank you, Buddy. Buddy's always thinking. I
2:31
can hear his mind from halfway across the
2:33
planet, just tumbling and tumbling, trying to
2:36
figure out all this Stuff because he comes up
2:38
with so many interesting questions.
2:40
Spaghettification, uh, first part of his
2:43
question is, is it an illusion? Or, you
2:46
know, if you were there, would you get
2:48
spaghettified good and proper?
2:50
Jonti Horner: It's a really good question. And that thing
2:52
of constantly thinking, constantly
2:54
questioning everything is fundamentally what
2:55
science is. We find things we don't
2:58
understand and we come up with ideas to
2:59
explain them and try and figure it out. And
3:01
there's always more to learn. So that's
3:03
fabulous. In terms of spaghettification, the
3:06
idea here is that if you were to fall into a
3:08
black hole, it would not be pleasant and
3:11
you would be stretched out gradually so
3:14
that you got stretched out like spaghetti.
3:16
And it would be a very painful and unpleasant
3:18
death. Um, from the point of view of the
3:20
observer looking down from above, it would
3:22
also be a death that takes an incredibly long
3:24
time because there is, as you fall into
3:27
a black hole, the light that's emitted
3:31
is slowed down by gravity. So you get this
3:32
kind of time dilation effect where somebody
3:34
watching you would see your clock tick ever
3:36
slower. So they get to watch your suffering
3:39
in great and slow and painful detail, which
3:42
is wonderful. But the idea behind
3:45
spaghettification comes from the
3:47
fact that if you are falling into
3:50
a black hole and your feet are nearer to the
3:52
black hole than your head is, your feet will
3:55
experience a stronger gravitational pull.
3:58
Now, this is kind of how the tides work on
4:01
Earth, to be honest. It's also how the
4:03
concept of the Roche limit comes about, which
4:05
is where we can work out how close to a
4:08
massive object like the Earth a smaller
4:09
object can get before it gets torn apart. All
4:12
of these things are built around the same
4:13
idea, which is that, uh, the strength of the
4:15
gravitational pull that you experience
4:19
from a given object falls off
4:22
as one over the distance squared. So the
4:24
further away you are, the weaker the
4:26
gravitational pull is. Now, if you're falling
4:29
into a black hole, that is
4:32
a solar mass black hole, if you
4:35
get a black hole, the mass of the sun,
4:38
it's tiny. We can actually work out
4:41
the radius of that black hole. I've not got
4:43
the number off the top of my head, but it's
4:45
very, very small. It's probably only a few
4:47
meters across, right? A
4:49
neutron star, the mass of the sun will be
4:51
about 2 km. A black hole will be much, much
4:53
smaller. What that means is that if you're
4:56
falling into that when you're getting very,
4:57
very close to it, the difference in
5:00
distance between your feet and your head from
5:02
the middle of that is actually a significant
5:04
fraction of the distance distance that you
5:06
are from it. So if you are 2 kilometers away
5:08
from this thing and you're 2 meters tall,
5:12
then your feet are 1 1000th nearer
5:14
than your head is. And that means that the
5:17
difference in distance leads to a very big
5:19
difference in gravitational pull between your
5:21
feet and your head. So you will get
5:22
stretched, and the closer in you get, the
5:25
more dramatic that gradient is
5:28
in the gravitational pull between your feet
5:30
and your head. Now you might think,
5:33
okay, well, that's fine, I'll just fall in
5:34
lying on my stomach. You'll still have the
5:37
same problem because the difference in
5:39
gravitational pull between your nose and the
5:40
back of your head will be bad. So your nose
5:42
will get stretched out and you look a bit
5:43
like Pinocchio, as would other parts of your
5:46
body be equally stretched out. So you're
5:48
doomed either way. But it is a very
5:51
real thing that would happen. The reason
5:54
that you could probably argue it's an
5:56
illusion is to the best of our knowledge,
5:59
we've never dropped a human into a black hole
6:00
yet. So the only times you see this are in
6:03
thought experiments or in expensive high
6:05
budget Hollywood movies. But the
6:08
physics behind it makes sense. Now, one of
6:11
the quirky outcomes of this is, uh, as you
6:14
increase the mass of a black hole, you'd
6:15
increase its radius, but
6:19
the, um, force
6:22
due to gravity falls off of one over, uh,
6:24
radius squared. So you have this slightly
6:26
bizarre thing that you would get this
6:27
happening if you were falling into a solar
6:29
mass black hole or an earth mass black hole
6:31
hole, if one existed. Supermassive black
6:33
holes, though, are so incredibly big
6:37
that the gradient between your
6:39
feet and your head would be very small when
6:41
you were near the event horizon, and you
6:43
wouldn't get spaghettified. So if you think
6:45
about the supermassive black hole in the
6:46
middle of our galaxy, the radius of that, I
6:49
believe, is wider than the orbit of Neptune,
6:52
30 astronomical units. So if you're near the
6:55
event horizon for a black hole of that size,
6:58
you are something like billions of kilometers
7:01
from the middle. And, uh, the distance
7:03
between your feet and your head is still 2
7:04
meters. So 2 meters out of billions of
7:07
kilometers is a very tiny difference. So
7:10
you wouldn't really be spaghettified. So if
7:13
you wanted to not be spaghettified while
7:15
falling into a black hole, I'd recommend you
7:17
go to the middle of the galaxy. Um, but I
7:20
would personally choose not to fall into a
7:22
black hole, given the choice. So it worked
7:24
out in white To Live.
7:25
Andrew Dunkley: It worked in the movie Interstellar. They
7:27
managed to get into one, but, um, yeah, that
7:30
was science fiction. Although I do Believe a
7:32
lot of the science they developed
7:35
for that film was, was based on
7:38
actuality. They just augmented it to suit
7:41
themselves.
7:41
But, uh, and the second part of Buddy's
7:43
question was, um, photons,
7:47
uh, can there be a wave and a particle at the
7:49
same time?
7:50
Jonti Horner: Yeah. This is going back to the
7:53
dawn of things like general relativity,
7:54
special relativity, and the dawn of the 20th
7:57
century where you get this wave particle
8:00
duality concept. And it's in
8:02
part based around the observed properties of
8:05
light and how it behaves. And you do
8:07
experiments when you do an undergrad physics
8:09
degree where you reproduce what they did 120
8:11
odd years ago. And, um, you can
8:14
get both kinds of behaviors.
8:17
The famous one is what's called Young's
8:19
double slit experiment. So you've got a light
8:20
source, like the light illuminating me at the
8:23
minute. And, um, you pass that light through
8:26
a wall where there are two very thin slits.
8:29
And then you look down from above and you can
8:30
see the light waves expanding away from
8:33
those two slits and interfering with each
8:35
other because they get diffracted through the
8:37
gap. And you usually illustrate this. I've
8:39
done this before in my undergrad teaching by
8:41
photographs of waves in the ocean passing
8:44
around barriers or passing through gaps. And
8:46
you see the same diffraction thing. So you've
8:48
got short waves coming towards the gap, and
8:50
then they go through two little holes and you
8:52
get circular ripples going out that interfere
8:55
with each other and you get these
8:56
interference patterns.
8:57
Andrew Dunkley: Yeah.
8:57
Jonti Horner: And, uh, that type of behavior is like acting
9:00
as a wave. It's behaving just like waves in
9:02
the ocean do. What you get,
9:05
though, is if you dim your light down, and
9:07
dim it down and dim it down, there's a weird
9:10
quantization effect. That light of a given
9:12
color you can't make
9:15
infinitely faint because you've got a
9:18
certain amount of energy carried by
9:20
photons. And so if you make your
9:23
light dim enough, you can isolate individual
9:26
packets of energy, which is what people
9:28
describe as photons. So if you get a really,
9:31
really, really, really faint light source,
9:33
the photons, and you have them
9:37
that double slit again, the light source
9:39
behind it, light going through the slit and
9:41
then hitting a sensor that measures the
9:43
light, you get individual flashes of light
9:45
where the photons hit. And so the photons
9:48
appear to be moving as packets or particles
9:50
of light, and you get a single flash. If you
9:53
record millions of those flashes, they
9:56
will form that same diffraction pattern.
9:59
So the light is behaving as both
10:02
a particle and a wave at the same time. The
10:05
really bizarre part of this for me, is the
10:07
fact that what this means is that
10:10
from a probability point of view, because you
10:12
get that diffraction pattern, because you get
10:14
those maxima and minima, all the
10:15
interference, what that means is that while
10:18
light is behaving as a particle, it's
10:20
technically going through both slits at once.
10:22
So that particle is in two places at one
10:24
time. And it all gets really, really bizarre.
10:28
Ties into, again, something I was talking
10:29
about in my, um, tutorial today for my
10:32
undergrad students. We were talking about
10:33
something called the Akovsky effect, which
10:36
is to do with light from the
10:39
sun being absorbed by an asteroid and then re
10:41
emitted by that asteroid, and you get a
10:44
transfer of momentum. If the asteroid's
10:47
rotating a little bit, the direction the
10:49
light is emitted is not the same as it goes
10:51
in. And that means you get a little bit of a
10:52
rocket thrust on the asteroid, and that can
10:54
change its orbit on really long periods of
10:56
time. One of my students said, I don't quite
10:58
get this. How can photons, which have no
11:01
mass, have momentum? Because you
11:04
need momentum in order to transfer momentum
11:06
to apply the thrust to the asteroid. So I
11:09
had to look into it then, and it turns out
11:11
that the concept of momentum is
11:13
fundamental to photons. So these packets of
11:16
energy traveling at the speed of light that
11:19
have no mass still have momentum.
11:22
And that momentum is entirely contained in
11:24
the energy and the oscillation of the
11:26
electromagnetic waves that make up that
11:29
packet of energy, that particle. And, uh, it
11:32
ends up going back to the famous equation
11:34
equals MC squared, which is the
11:37
relationship between energy and matter. Now,
11:39
equals MC squared is a simplification of a
11:41
more complex equation Einstein came up with,
11:44
which, off the top of my head, I think it's E
11:46
squared equals P squared C
11:48
squared plus M m squared C to the
11:51
4. So this is the total
11:54
energy is proportional, is related to the
11:57
momentum times the speed of light, plus
12:00
the mass times the speed of light squared. So
12:02
if you've got something moving very slowly,
12:04
then it simplifies to equals MC squared
12:07
because there's not much momentum. But if
12:08
you've got something traveling at the speed
12:10
of light, the mass is zero. So the MC squared
12:13
bit vanishes, and you just get the energy is
12:16
equal to the momentum times the speed of
12:18
light. So in other words, the momentum of a
12:20
photon is equal to the energy of the photon
12:23
divided by the speed of light. Which means
12:26
that even though photons have no mass,
12:29
they still carry momentum, and it's a
12:31
fundamental part of them. And what this tells
12:33
you more than anything else is when you get
12:34
to the quantum scale. Tiny little things.
12:37
When you start dealing with relativity,
12:39
nothing makes sense. It's not common sense.
12:42
And, um, we're still trying to understand it,
12:44
and it's all really hard. But all of that is
12:46
tied into this wave particle duality and the
12:49
Young's double slit experiment. And, um, to
12:51
be honest, it makes all our heads hurt.
12:53
Andrew Dunkley: Yeah, it does. But great, um, question,
12:56
buddy. Thanks for sending it in.
13:00
Okay, we checked all four systems, and.
13:02
Jonti Horner: Being with a girl, Space Nuts.
13:04
Andrew Dunkley: Uh, our next question. Jonti comes from
13:06
istok. Uh, he says hi. I like your
13:09
Space Nuts podcast. So do we. Uh, a, ah,
13:12
neutron star is very dense as it contains
13:14
only neutrons. So no empty
13:17
space between the core and electrons. Right.
13:20
What happens to the matter at a
13:23
black hole? Is there empty space, uh,
13:26
also inside neutrons? And can they
13:29
be even denser? Thank you. ISTOK
13:32
from Slovenia. We haven't had many questions
13:35
from Slovenia. Nice to hear from you. Um,
13:38
this one, um, I got to confess, is
13:40
way out of my ballpark.
13:43
Jonti Horner: This is a really, ah, awesome question. And
13:46
it's pushing the boundaries of, we don't know
13:50
the way all this works. We talked about white
13:52
dwarfs earlier. If you compress
13:54
matter into a smaller and smaller space, you
13:57
can get nuclear fusion happening, propping up
13:59
a star. And that's why stars shine. Star,
14:01
like the sun, gets to the end of its life,
14:03
blows off its outer layers, can't support
14:05
itself with nuclear fusion anymore because it
14:07
can't get the fusion going. So gravity wins
14:10
and collapses everything in. And eventually
14:13
you get to a point where atoms are propped up
14:16
against each other, held up by something
14:18
called electron degeneracy pressure. Um, and
14:21
what that is effectively is you've got of a
14:23
given atom, as Iztoch's inferring here,
14:25
you've got the nucleus in the middle, and,
14:27
um, then way, way on the outside, you've got
14:29
this cloud of electrons going around it. And
14:31
those electrons are negatively charged. And
14:34
the analogy people often use here is
14:35
something like the nucleus is like a grape at
14:37
the middle of a football field, and the
14:39
electrons are, like, running around the
14:41
boundary. So there's a lot of empty space in
14:43
there. Which means if you take the mass of
14:45
the sun and compress it down so that
14:48
all the atoms are, ah, butted up against each
14:51
other, so their electron clouds are pressing
14:53
on each other, and you've got rid of all the
14:54
space outside the atoms. You get an object
14:57
about the size of the Earth. So you take an
15:00
object, the mass of the sun, um, squash it to
15:02
the size of The Earth. And at that point, the
15:04
electron clouds around each atom butt up
15:06
against each other, and uh, the negative
15:08
charge and the negative charge repel each
15:10
other and you get a pressure that holds it
15:12
up. That's called electron degenerative
15:15
pressure. And that works. And you can keep
15:18
adding mass and adding mass, but eventually,
15:20
if you get to about 1.4 times the mass of the
15:22
sun, a point you call the Chandrasekhar
15:24
limit, the gravitational pull is strong
15:27
enough to overcome the repulsion of those
15:29
electrons, and gravity wins. And so things
15:32
keep collapsing further, and that squashes
15:35
the electrons and the protons in the atoms
15:37
together, making neutrons. And so the atoms
15:40
of those, well, m, all those atoms that made
15:42
up the white dwarf get turned
15:45
into neutrons. And so
15:48
suddenly you've gone from a football pitch
15:50
size to a grape. Everything's squashed into
15:52
the nucleus and everything keeps
15:54
collapsing. But eventually neutrons butt up
15:56
against each other and the strong nuclear
15:59
force I think it is stops them
16:02
collapsing any further. There's a new
16:04
pressure, which is called neutron degeneracy
16:05
pressure, and that holds neutron stars up.
16:09
And so you get something the mass of the sun,
16:12
but the size of a city a few kilometers
16:14
across. Okay, Keep adding mass to that and
16:16
you eventually reach critical mass. I've
16:18
forgotten the name of it. But the critical
16:19
mass for neutron stars is thought to be about
16:21
three times the mass of the sun. And at that
16:24
point, gravity is strong enough that the
16:26
strength of the neutrons pushing apart cannot
16:28
hold them up against gravity, and gravity
16:30
wins. So things collapse down
16:33
even further. And this is where it gets to
16:35
the point of our understanding starting to
16:37
fail. There are some suggestions that if
16:40
you squash neutrons together with enough
16:42
force, you can compress them down
16:45
so that inside, inside that neutron,
16:48
you've got a lot of empty space and some
16:50
subatomic particles, quarks. And you could
16:53
squash them together until the force between
16:55
the quarks prevents them
16:57
squashing in. Any further. And you could get
16:59
an additional kind of thing, which is why you
17:01
get the concept of a quark star. And some
17:03
people have speculated that within quarks
17:05
you've maybe got sub subatomic particles,
17:07
which I think are called pions or P Os or
17:09
something like this. So maybe after a quarks
17:12
are, you can get smaller still.
17:14
Fundamentally though, every time
17:17
mass scale, you'll reach a point where no
17:19
force we can imagine is strong enough to hold
17:21
it up and it'll collapse further. What you
17:24
get with a black hole is secondary
17:27
to this. It's kind of separate to it, which
17:29
is that the amount of mass you've got
17:32
means that to escape from that mass within
17:35
that small area, you'd have to travel faster
17:37
than the speed of light. So that's where you
17:40
get the event horizon of a black hole. But
17:42
the physical object inside the black hole, if
17:44
there is one, and we don't know if there is
17:45
one, is probably smaller than the size of
17:47
that event horizon. Now, I
17:50
am not an expert in this. My understanding
17:52
from what I've seen written is that people
17:54
think quark stars would be big
17:57
enough that the gravity on their surface is
18:00
low enough that light could escape, so they'd
18:02
be bigger than the event horizon, so that
18:03
we'd see them as physical objects. But it may
18:06
be that the next step down is smaller than
18:08
the event horizon. So you have a black hole.
18:10
Fundamentally, what happens with the matter
18:12
inside a black hole and, um, what empty space
18:15
you have inside neutrons and stuff is pushing
18:17
the boundaries of our knowledge of how matter
18:19
works and how particle physics works. We do
18:22
think there are these subatomic particles.
18:24
There's a lot of evidence for that. And
18:25
that's where the RDF quark stars come from.
18:28
Knowledge of what quarks are made upon is
18:30
really pushing the boundaries of what we
18:32
know. And I'm, um, nowhere near qualified to
18:34
comment on that, other than that there is
18:36
speculation that you could possibly have even
18:39
smaller components that behave
18:42
differently. And this is where, as we get
18:44
more energetic particle colliders in the
18:46
future, as we get more better telescopes,
18:49
better instrumentation all around, these are
18:51
the kind of questions that people want to
18:53
answer as we push that boundary of knowledge
18:55
back. But it's really, at this point is
18:58
SOC is asking questions that are at the
19:00
boundaries of what our knowledge of modern
19:02
physics is. And, uh, it's by asking these
19:04
kind of questions that we'll learn the
19:06
answers. But we're not there yet.
19:08
Andrew Dunkley: No, no, we're not. But if, uh, we didn't ask
19:11
questions like this, we'd never go looking
19:13
for the answers, and we'd probably
19:16
stagnate as a species.
19:18
Jonti Horner: So, I mean, if you go back a long time, you
19:20
know, if we didn't ask questions, we'd
19:22
probably still be sitting around saying, me
19:23
wish fire hot and not actually having the
19:26
ability to have fires in. A day like today
19:28
will be extremely miserable with the drizzly
19:30
rain, because at least the fire that I've had
19:31
on has kept me warm.
19:33
Andrew Dunkley: Yeah, yeah, absolutely. Uh, thanks for
19:36
the question. Istok. Lovely to hear from you.
19:38
Hope all is well in Slovenia.
19:40
This is Space Nuts with Andrew Duckley and
19:42
Jonti Horner.
19:46
Generic: Three, two, one.
19:49
Andrew Dunkley: Space Nuts. Our next question
19:52
is, uh, an audio question I do
19:55
believe. Now, forgive me, I may have got your
19:58
name wrong. I couldn't quite pick it up. Uh,
20:00
maybe it was the accent, maybe it was just my
20:02
lousy capacity to translate, but
20:05
I think it's Foster.
20:07
Speaker D: Hello, Andrew. Hello, Fred. And
20:10
hello, Jonathan. I am from
20:13
Norway, and I have a question for you.
20:16
Uh, in relation to Interstellar, the
20:19
movie, probably my favorite space
20:21
movie of all time. And
20:24
I have a question about the wormhole. And
20:27
what kind of parameters
20:29
theoretical. Has to be in order or to
20:32
be in place for this to be possible and
20:35
everything that we will discover or
20:38
maybe, uh, youth, such a
20:40
phenomena at some point. Thank you.
20:44
Andrew Dunkley: Okay. Um, thank you, Foster. I think that's
20:47
what your name was. Norway. I was there
20:49
recently. Um, only in the last few months.
20:51
And what a beautiful country you have.
20:54
I got to stop in, I think, four or
20:57
five different places, um, throughout
21:00
Norway. And I learned a lot about the. The
21:02
country, uh, uh, Jonti.
21:05
Because, uh, they don't have much arable
21:07
land. It's a.
21:08
Jonti Horner: It's.
21:09
Andrew Dunkley: They've got water and they've got mountains.
21:11
There's not much flat ground. It's so un
21:14
Australian. Very un
21:16
Australian. Um, and because they've got so
21:19
much water, uh, they can generate a lot of
21:21
electricity. And nobody pays for electricity
21:23
in Norway, from what I was told. Um,
21:26
but they don't really have much
21:29
room to grow crops. And, uh, and it's too
21:32
cold most of the time anyway. Uh, that said,
21:35
when we went to North Cape, which is the
21:37
northernmost tip of Europe, which is
21:39
obviously in Norway, as in north,
21:42
um, 28 degrees. It was
21:45
28 degrees. And the locals were freaking out.
21:47
That was a heat wave. Uh, to us it was just
21:50
beautiful. But, um, one
21:53
thing I did notice, and you'd probably be
21:55
aware of this being, uh, from the Northern
21:57
hemisphere, their summer,
22:00
where most of the population lives, their
22:03
summer is not like a summer here
22:06
because they are further north than we are
22:09
south, if that makes sense.
22:11
So our summers can be much more severe. Uh,
22:15
um, but
22:18
their summers are very mild,
22:22
especially when you get to places like
22:23
Greenland and Iceland and, uh,
22:27
even in Canada, places like that. It's a
22:30
different world.
22:31
Jonti Horner: Yeah, I mean, I know for a fact, having grown
22:33
up in the uk, and I, uh, suspect that heat
22:35
wave in Norway was brutal that he hits
22:38
different in those countries because the
22:39
buildings are engineered to keep you warm,
22:41
not to keep you cool.
22:42
Andrew Dunkley: Correct.
22:43
Jonti Horner: And so, yeah, I'm complaining about the
22:45
horrible night I had the other night with the
22:47
power outage and the heat wave that we had.
22:49
But it was made more bearable by the fact
22:52
that the design of this house is more around
22:55
keeping people cool in summer and keeping
22:56
them warm in winter. Whereas when I was doing
22:59
my PhD in Oxford back in 2003, we
23:02
had what was then the hottest summer on
23:03
record in the UK and now is a footnote in
23:06
history because things are much warmer now
23:07
than they were. But we had a couple of days
23:09
that were in the mid-30s. And I'm in this old
23:12
building that is a couple of hundred years
23:14
old with south facing windows to get the
23:17
light, northern hemisphere, the sun's in the
23:19
south, um, on the ground floor. So you could
23:21
only open these floor to ceiling windows by
23:23
about an inch because they're security locked
23:25
down. And uh, no air conditioning. A lot of
23:28
computers in there. It was absolutely awful.
23:31
Um, the other thing that I really notice is
23:34
I'm into one where I'm 27 degrees south. The
23:37
day length barely varies. When I grew up, you
23:39
know, in the winter I'd go to school in the
23:41
dark and come home in the dark. And here the
23:44
day length barely varies. But we're already
23:46
well off topic from, um, the awesome
23:48
question.
23:49
I should say that my movie viewing
23:52
over the last decade or 10 or 15 years has
23:55
been much more limited thanks to how busy
23:57
I've been in my career. And Interstellar has
23:59
been on my to watch list for years and never
24:02
quite happened. No, we've got Brilliant,
24:04
Gotta do it. And um, it's on the list and I
24:07
wish I'd seen it at the cinemas, but it's
24:08
always been a not today thing. It's never
24:11
quite happened.
24:12
Andrew Dunkley: You know, I've watched it four or five times.
24:15
Yeah, I love it. And I think
24:18
what makes it for me being someone in radio
24:20
is the musical score that goes with
24:23
it. It is phenomenal.
24:27
Jonti Horner: It's meant to be amazing and I'm just sad
24:29
I've not got around to seeing it yet. But one
24:30
of the things I know about it is that it is
24:33
pretty hardcore on the science. But they did
24:35
a really good job of getting some of the
24:36
world's really leading theoretical physicists
24:40
to give input and get really good scientific
24:42
advice. And it does to my understanding.
24:45
And I say this with a bit of a caveat that
24:47
I've not seen it. But my understanding,
24:48
talking to colleagues is it does really well.
24:51
What I like in good science fiction is where
24:53
it gets the science right, except where it
24:55
needs to get the science wrong to make the
24:57
plot advance. Um, exactly. And I'm always
24:59
really happy with that. I get really grumpy
25:01
with films that get the science wrong to no
25:03
good reason. I watch films and they've
25:06
got a night sky, and it's not the Earth night
25:08
sky. And it's like you're on Earth. It is
25:11
really cheap to point a camera at the sky and
25:13
get a picture. Why would you make up a false
25:15
night sky? There's no need for that. But if
25:18
you do everything you can to get the science
25:20
right, or the science to fit our best current
25:23
understanding in the case of things we've
25:25
never directly experienced or seen, but you
25:28
circumvent that to make the plot work, I'm
25:30
totally cool with that. That's a very knowing
25:32
use of science.
25:34
This is all about wormholes, which are a
25:36
staple of science fiction because
25:39
they are a hypothetical way that we could
25:41
move from one place in the universe to
25:43
another at speeds much greater than the speed
25:45
of light, by essentially cutting out the
25:47
middleman. And the way it's always envisaged
25:50
is to envisage the universe drawn on a two
25:52
dimensional sheet of paper and then folding
25:54
the sheet of paper so that two places that
25:56
are nowhere near each other touch and saying,
25:59
what if you could tunnel between them?
26:01
Wormholes have their origins in
26:04
particular solutions to the equations from
26:06
Einstein's general relativity. And they are
26:09
purely theoretical constructs at the minute.
26:11
They're possible solutions to the model that
26:13
Einstein developed that offer the
26:16
possibility that you could have
26:19
instantaneous travel between two distant
26:21
points. There's a lot of debate over whether
26:23
they are anything more than a theoretical
26:26
construct. And of course, this is all
26:29
predicated on, um, the idea that
26:31
Einstein's model of the universe is
26:34
a correct analysis of what's actually there.
26:37
And it may well be that in 50 years or 100
26:39
years, when we've got incredibly more
26:40
powerful observing tools than we have now, we
26:42
start to see the cracks in Einstein's model
26:45
just the same way that we did with Newton's
26:46
gravitation a couple of hundred years ago.
26:50
There are a few variants of wormholes that
26:52
have been proposed based on different
26:54
solutions to those
26:57
theories. Some of them have even come about
26:59
kind of tied to. You could potentially have a
27:01
rotating black hole that would turn into,
27:04
that would allow you to travel through the
27:06
black hole without getting destroyed and use
27:08
it as a tunnel to somewhere else. There
27:11
are also solutions to those equations
27:15
which could let you set up one of these
27:17
wormholes. One of the variants of this is
27:19
known as an Einstein Rosen bridge, I believe,
27:21
um, that could set up a permanent tunnel that
27:24
could be traversable. But in order to make
27:26
that work, you need material which has
27:29
negative energy, which often gets talked
27:31
about as exotic matter. And I've been
27:34
listening to an audiobook series that's very
27:36
good, fun, but very pulpy, called
27:38
Expeditionary Force. And they use wormholes
27:40
all the time. And they're always talking
27:41
about things made of exotic matter by
27:43
technologically advanced species millions of
27:46
years more advanced than we are. It's become
27:48
a staple of science fiction as uh, to
27:51
whether we will ever find them or ever
27:54
be able to use them. We simply don't know yet
27:56
at uh, the minute. They're a purely
27:57
theoretical constructs. So they're kind of an
27:59
extreme prediction of one model of how we
28:02
think the universe could work. They are
28:05
possibly something that with sufficiently
28:07
advanced far future technology, you could
28:10
envision the ability to make them and control
28:12
them. But that would require us to have
28:15
technological advances beyond what we can
28:17
imagine here and probably physics to work
28:19
differently to how we currently understand
28:21
that it would do. I'm loath to say we
28:24
couldn't do it because that strikes me as a
28:26
bit like the people who in 1910s said we will
28:28
never have heavier than air flight just
28:30
before the Wright brothers flew. Um,
28:33
because we don't know everything. We, we're
28:36
in this little bubble of knowledge in an
28:37
ocean of things, um, that we don't
28:40
know yet in an ocean of darkness. And um,
28:43
these things like wormholes are uh, natural
28:46
products of our efforts to push that boundary
28:48
of knowledge further. All of this is a
28:51
very long winded, say, way of saying I don't
28:54
have the real knowledge of how all this
28:56
works. I'm not that kind of theoretical
28:59
physicist. It's all very much
29:01
beyond me. I greatly admire the kind
29:04
of scientists that have come up with these
29:06
ideas. I think they are fabulous, fabulous
29:08
ideas. And if the model is
29:10
correct, then wormholes could exist.
29:13
You then have the leap of could they be
29:15
stable for long enough for us to ever observe
29:17
them? And of course the most important thing
29:19
about a theory is it makes testable
29:21
predictions. And so I'd love to see
29:23
observations in the future confirm that
29:25
wormholes can exist. To then have a leap
29:28
beyond that to could we ever develop them and
29:30
use them? I'd love to think we will do. But
29:33
I think unlike the search for life elsewhere,
29:35
where I think there's a chance we'll know the
29:36
answer in a lifetime, I think with this it's
29:39
very unlikely we'd know the answer within our
29:41
lifetime. Unless the answer is no. And the
29:44
answer is no would come about Us getting a
29:46
newer model for how all these things work to
29:48
explain new observations that no longer
29:51
offers this as a possibility. Um, I don't
29:53
think that's going to happen in all honesty.
29:56
But yeah, it's an awesome question.
29:59
I wish it was something I could be more
30:00
knowledgeable about. But, um, if you went
30:02
back 400 years, it was possible for one
30:05
person to have the entirety of the world's
30:07
knowledge. And that's why you've got these
30:08
incredible polymaths who could be chemists
30:11
and engineers and biologists and physicists
30:13
and astronomers all at the same time.
30:16
Nowadays the breadth of human knowledge is so
30:18
incredibly vast that nobody
30:21
can be an expert in all of it. In fact,
30:22
you're normally an expert in a very narrow
30:24
area. And it's very fair to say that
30:26
wormholes and um, the
30:29
complexities of higher dimensional space time
30:32
and theoretical physics in that sense, and
30:34
you know, the extreme extrapolations of
30:36
general relativity are uh, way outside my
30:38
wheelhouse. I'm not really qualified to say
30:40
much more than that, even having done a bit
30:42
of reading around it.
30:43
Andrew Dunkley: I like to think that
30:47
fundamentally all things are possible. But
30:49
uh, I know, um, traveling faster than
30:52
light speed isn't because of the amount of
30:54
energy it requires, but maybe folding space
30:57
or developing wormhole technology could
30:59
be the workaround.
31:02
So um, yeah, let's put a pin in
31:05
that one for future reference when they've
31:07
got it all figured out. But um, yeah,
31:09
wormhole technology comes up in
31:12
interstellar, uh, as created by a fourth
31:14
dimension race. Um, I won't say any
31:17
more than that, but uh, Foster, thanks for
31:20
the question. Uh, I loved it, it was
31:22
terrific. And yes, I agree with you. Probably
31:24
my favorite,
31:27
if at the very least in my top
31:30
three, um, um,
31:32
science fiction films, uh, although it's
31:35
pretty close to not science fiction in many,
31:37
many ways. Good on you, Foster. Thanks for
31:39
the question.
31:42
Jonti Horner: Okay, we checked all four systems and.
31:44
Andrew Dunkley: Being with a go space nets now, final
31:46
question today comes from Rob.
31:49
As I understand the only way
31:52
out of a singularity is by Hawking
31:54
radiation. However, isn't the Big Bang
31:58
another example? If so, then at a
32:01
critical universal size an explosion
32:04
is imminent. Uh, this suggests that
32:07
there were a number of singularities before
32:09
the Big Bang that combined to reach
32:11
critical Big Bang mass. What do you think?
32:14
Uh, could the very early black holes suggest
32:17
that a, ah, number were floating around
32:19
before the Big Bang and attracted mass
32:22
from the Big Bang to form the galaxies?
32:25
Jonti Horner: Wow.
32:25
Andrew Dunkley: Rob put a lot of thought into that one.
32:28
Jonti Horner: Absolutely. And this is yet another one that
32:31
gets to pushing the boundaries of any of our
32:33
knowledge, to be honest. And this
32:36
question from Rob is a really
32:39
good illustration of where the boundaries of
32:41
analogy when it comes to cosmology and
32:43
cosmogenesis, the origin of the universe,
32:46
are, ah, where science and philosophy meet,
32:49
where you start getting to the point where
32:52
you are going so far beyond what we can
32:54
observe and what is possible
32:57
to understand with our current laws of
32:59
physics. That discussion of it moves away
33:01
from science and into the realms of physics,
33:03
philosophy and thinking about how we think.
33:06
And uh, the reason I say that is that our
33:08
current best understanding, as I remember it
33:11
from the things I've learned, is that,
33:15
uh, space and time are inherently properties
33:17
of the universe. Which means
33:20
that the question of what is before
33:23
the Big Bang or the question of what's
33:25
outside the universe are things that are
33:28
questions of philosophy rather than science.
33:31
Because by definition you can't have a before
33:33
the Big Bang when time only started at the
33:35
Big Bang and time is a property of the
33:37
universe. Similarly, you can't have a concept
33:39
of outside the universe when space is of the
33:42
universe. Yeah, now as I say this, to me
33:44
really gets to be philosophy rather than
33:47
science because that makes my head hurt. And
33:49
I think anything that makes my head hurt can
33:51
be described as philosophy. Um,
33:54
but it is a lot of it's about how we think
33:56
and how we visualize stuff. So I suspect
33:59
if we got somebody on who was one of the
34:01
world's leading cosmologists, they could
34:02
answer this a lot more clearly. But they'd
34:04
probably be saying that we can't really say
34:06
anything about what was happening before the
34:08
Big Bang because before the Big Bang is a
34:11
meaningless concept. Before the Big Bang,
34:13
time didn't exist.
34:15
Andrew Dunkley: Well, the question has been asked
34:17
directly to us in the past, what was there
34:19
before the Big Bang? And Fred's answer is
34:22
always nothing. Well,
34:25
no, no, no, he doesn't say nothing. He says
34:27
we don't know.
34:29
Jonti Horner: It is really a we don't know. Now
34:31
there are a number of theories out there
34:34
because this verges on philosophy and um,
34:37
religion. Not in the, not in the sense of any
34:39
given named faith, but rather
34:42
the point at uh, which you move from
34:45
evidence and theory and prediction
34:48
to faith. Um, and
34:52
I'm not myself religious, but I've got a lot
34:54
of colleagues that are. And there is, despite
34:56
what some people try and manufacture, there
34:58
is no conflict between religion and science
35:00
at all. Um, Terry Pratchett, who I
35:03
obviously put a lot of salt by because I
35:04
mentioned him very, very often, had some
35:06
really good discussions of this in the
35:07
discworld books and the concept
35:10
that. I think it's in the science of
35:12
Discworld books that science and religion are
35:14
orthogonal and that science. Science operates
35:17
in the absence of belief because it's about
35:19
evidence, whereas belief operate. Religion
35:22
operates in the domain of outside of evidence
35:25
because it's about belief. And,
35:28
you know, I don't need to believe. This table
35:30
in front of me is there because I put the
35:32
evidence of my hand resting on it in my
35:34
microphone set. There's a lot of really
35:36
interesting stuff there. And, uh, the reason
35:37
that I've gone on that little bit of a detour
35:39
is that questions about what happened before
35:42
the Big Bang are questions that, uh, are
35:45
beyond what we can. What of. Beyond what we
35:47
can know. Because all of our ability to
35:49
observe and measure is limited to
35:52
the results of the Big Bang in terms
35:55
of space and time.
35:58
Those started at the Big Bang. So to try and
36:00
understand anything about before the Big Bang
36:02
with those in our current understanding of
36:04
how it works becomes a matter of religion or
36:07
faith, because there is no way of having
36:08
evidence either way. Um, apologies for a
36:11
bit of a background noise, by the way. The
36:13
rain is pounding on the wonderful roof here,
36:15
which is a very Australian experience.
36:16
Andrew Dunkley: Uh, now I'm a thousand kilometers away from
36:18
you, but it just started raining here as
36:20
well.
36:21
Jonti Horner: Spooky action at a distance is what that is.
36:24
Andrew Dunkley: Yeah, it was probably a wormhole.
36:26
Jonti Horner: Yeah, absolutely. It's teleporting through,
36:28
which is why it's been so dry here recently.
36:30
You're getting all the fun. Yeah.
36:32
So with this question from Rob, the challenge
36:35
is that you're asking the questions that
36:36
we're all asking, trying to understand,
36:39
but they're not questions we can really
36:41
answer when it comes to things outside of the
36:43
current universe. What that's led to is a
36:46
number of different proposals of theoretical
36:48
before the Big Bangs. One is that the Big
36:51
Bang is the first thing that there ever was
36:53
and will expand for forever, and that's it.
36:55
And it's doom. One is that
36:58
you have these Big Bangs followed by Big
37:00
Crunches, and you get the cyclical nature of
37:02
the universe with a reset. Um, a lot of our
37:04
current theories suggest that the expansion
37:06
of the universe is speeding up rather than
37:08
slowing down, which argues against that.
37:10
But we know in the past,
37:13
and this is where it gets more to philosophy
37:15
and religion and faith and complexity as
37:18
well, is that, uh, in the early days of the
37:20
universe, the different forces were unified
37:23
and you get phase changes in the universe as
37:25
the expansion happens in the universe cools.
37:28
Um, and that's all in the very early time.
37:30
But it's possible. And I've never found
37:33
anyone who can explain to me that this
37:35
wouldn't be possible. But it might be
37:36
entirely wrong. This is jaunty speculation.
37:39
Who's to say that there isn't another phase
37:40
change at some point where something that we
37:42
can only see as one force freezes out into
37:44
two separate forces? Now we see examples of
37:47
this all over the place. It's a total hop.
37:50
But when I was doing my second postdoc, I was
37:53
at the Open University in the UK and at
37:55
uh, one of the conferences I went to, I met a
37:57
young woman who was doing a chemistry based
37:59
degree looking at chemistry on the moon
38:01
Titan. And she was interested in
38:04
the availability of different chemical
38:05
reactions as to whether a place like Titan,
38:08
180 degrees below freezing, could have the
38:11
potential for life, given that there's liquid
38:13
there in the form of liquid ethane and
38:14
methane. And the standard accepted wisdom is
38:17
no there isn't, because the more you cool
38:19
down, the fewer chemical reactions are
38:20
available. Just doesn't happen. But she
38:23
looked at benzene, which is a chemical, a,
38:26
ah, compound that at uh, room temperature
38:28
there's a single version of benzene. You have
38:29
the benzene ring. What she found was
38:32
that if you cool benzene down to the
38:34
conditions you get on Titan, benzene forms
38:37
three different isomers. They're all benzene,
38:40
but they're different shapes of those six
38:42
carbon atoms in a ring. At, uh, room
38:44
temperature, it's got enough energy that it
38:46
vibrates around and they all blur out and you
38:48
just get a single version. But you cool it
38:49
down and you freeze it out to three distinct
38:51
versions of benzene with slightly different
38:54
chemistry. So suddenly by cooling it down and
38:56
freezing it out, you get three times the
38:57
availability of different chemical reactions
38:59
as more chemistry can go on. And the
39:02
freezing out of the forces and the breaking
39:04
of them into other forces seems to be a bit
39:07
like that. Now it's way beyond my expertise
39:09
and my knowledge. But this is what
39:12
happens when you push really at the boundary
39:14
of not just what we currently understand and
39:16
we know, but what we can possibly observe.
39:19
And so questions like this about the origin
39:21
of the universe, about primordial black holes
39:23
and where they come from, about what the
39:26
conditions were before the Big Bang,
39:29
even though that's meaningless. These are
39:31
really at the limits of what we know and what
39:33
we understand, and they're pushing beyond
39:35
them, but they're also at the limits of what
39:37
we believe that we could ever observe
39:40
if our current models of how everything works
39:43
are correct. And that's always a big caveat,
39:45
because they might turn out not to be. But at
39:47
the minute, the received wisdom seems to be
39:49
that we can never know
39:52
of something earlier than the Big Bang
39:54
because that's when time and space
39:55
originated. We can never know about anything
39:58
outside the universe because the concept of
40:01
space is you can't have an outside, because
40:03
if you were outside, there will be no space
40:05
and therefore you're not. Yeah, it's all a
40:07
bit weird unless.
40:08
Andrew Dunkley: You go down the multiverse part.
40:10
Jonti Horner: Yes, and that's what I was going to say. You
40:12
get some people speculating that you can have
40:14
multiple universes in parallel
40:17
kind of spaces that cannot really strongly
40:19
interact with each other, but where they
40:20
overlap, you might see ripples in the
40:22
microwave background. And so you might see
40:24
some evidence in the structure of our
40:26
universe about the existence of other
40:28
universes that we can't ever touch. But like
40:30
ripples on the surface of water are evidence
40:32
of the wind. You can't see the wind, but you
40:35
can see its effect. So I appreciate. Rob,
40:38
I've probably not got anywhere close to
40:40
answering your question, but what I've done
40:42
instead is explained why I can't. And part of
40:44
that is that I'm not qualified to. I don't
40:46
have the knowledge. But it's also, I think
40:48
you're asked asking questions that
40:50
fundamentally we cannot yet answer and, ah,
40:52
we may never be able to answer. And that's
40:55
why these kind of discussions are fun. It's
40:56
the kind of thing where you sit around a
40:57
campfire and have a couple of drinks or
41:00
whatever and have these deeper, meaningful
41:02
discussions, because it's part of trying to
41:03
understand the entirety of what there is to
41:05
know.
41:07
Andrew Dunkley: Gotcha. Yeah, look, I'm with you there. It's,
41:10
um. How can we know?
41:13
That's the question that comes to my mind
41:14
when I hear a question like Rob's, which I'd
41:17
love to know the answer to.
41:19
Jonti Horner: Me too.
41:19
Andrew Dunkley: How can we possibly know? It's. Yeah,
41:23
um, what, what, what was before the Big
41:25
Bang? What's outside the universe? Um,
41:29
yeah, they're all just
41:32
impossible.
41:33
Jonti Horner: Even beyond that, even if we could get an
41:35
answer, would we be able to understand it? It
41:37
may well think there are answers to this that
41:40
are there, but are so far beyond us at the
41:41
minute that we don't even have the framework
41:43
to formulate those answers.
41:47
Andrew Dunkley: Correct. All right, Rob, thanks for your
41:49
question. Lovely to hear from you.
41:50
Thanks to everyone who contributed to this
41:53
week's Q and A session. If you would like to
41:55
do so, jump on our website SpaceNuts
41:58
IO and click on the AMA link at
42:01
the top. And you can send us a text question
42:04
by giving us your name, your email address
42:06
and uh, putting your message in there. Don't
42:08
forget to tell us who you are or where you're
42:10
from. But if you scroll, uh, down a bit,
42:12
there's the uh, start recording button. If
42:15
you've got a device with a microphone, like
42:18
a, I don't know, a smartphone
42:21
or most computers these days, particularly
42:23
laptops and MacBooks and things like that,
42:26
uh, you can send us an audio question. We'd
42:28
love to get some of those as well. So please
42:30
send them in to us and have a look around on
42:32
our website while you're there. And don't
42:34
forget social media, where, uh, we've got a
42:36
strong presence on Facebook and Instagram
42:39
and the um, the group that was created
42:42
by Space Nuts listeners, the Space Nuts
42:45
podcast group on Facebook.
42:48
Very, uh, much worthwhile joining that group
42:50
and talking amongst each other and solving
42:52
all the problems of the universe, including
42:54
Rob's probably. Uh, so, yeah,
42:57
check um, it out. Just do a search for Space
42:58
Nuts on Facebook or Space Nuts podcast group.
43:02
Uh, they're both there. Both have,
43:05
um, thousands upon thousands of followers. So
43:07
it's fantastic. Love it. Uh, and
43:10
Jonti, we are done. Thank you so much for
43:12
tackling all of that. They were some pretty
43:14
curly questions, especially the spaghetti
43:15
one. Lots of curls in that.
43:18
Jonti Horner: Make me hungry as well.
43:19
Andrew Dunkley: Yes, yes, I had spaghetti for dinner earlier.
43:22
In fact, uh, we'll catch you next time.
43:24
Jonti, thank you so much.
43:26
Jonti Horner: It's a pleasure. Thank you and awesome
43:27
questions. Really enjoyed it. Even if my head
43:29
now hurts.
43:31
Andrew Dunkley: You can take something for that. Uh, and,
43:34
uh, thank you for, for listening. Don't
43:36
forget, uh, to, um. Yeah, as I said, uh, send
43:39
your questions in via our. And thanks to Huw
43:41
in the studio, who couldn't be with us today
43:43
because he and his wife were having a big
43:46
night out, which is terrific and they deserve
43:48
it. And from me, Andrew Dunkley, thanks for
43:50
your company. Catch you on the next episode
43:52
of Space Nuts. Bye. Bye.
43:56
Jonti Horner: You'll be listening to the Space Nuts
43:58
podcast, available at
44:01
Apple Podcasts, Spotify,
44:03
iHeartRadio or your favorite podcast
44:06
player. You can also stream on
44:07
demand@bytes.com.
44:09
Andrew Dunkley: This has been another quality podcast
44:12
production from bytes.um com.