Andrew Dunkley: Hi there. Thanks for joining us. This is a Q and A edition of
Space Nuts. My name is Andrew Dunkley. It's
good to have your company. Uh, today, uh, we
will be hearing questions about, uh,
the universe being inside a black hole. In fact, I
think they're suggesting it was born in a black hole and
is stuck in there. And how do we get out?
We'll also be looking at a new gravity theory. Uh,
theory Hubble tension. Not
surprisingly, questions about planet nine with the
most recent announcement of something being out there that's not
planet nine. And, um,
getting gravity assistance to Max
Delta V. Those are all the questions
coming up on this episode of space nuts.
Voice Over Guy: 15 seconds. Guidance is internal.
10, 9, ignition
sequence time. Uh, space nuts. 5, 4, 3,
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Andrew Dunkley: And Fred Watson Watson is with us again to solve all
these little riddles.
Professor Fred Watson: Hello, Fred Watson. Hello Andrew. Nice to, um, help you solve the
riddles.
Andrew Dunkley: Uh, I don't know anything.
That's why I bring you along.
Professor Fred Watson: Oh, good. Well, I'm about to be of assistant.
Andrew Dunkley: Makes it so much more interesting when there's two people talking.
Monologues are just so boring, don't you reckon?
Unless it's a super interesting person like yourself.
Right.
Professor Fred Watson: No, I'm, I'm capable of boring the pants off people as,
uh, people have assured me before. So that's
all right.
Andrew Dunkley: So we've got a lot to get through and uh,
it's, it's even trickier this week because we do have a
technical, uh, issue, which means you are
going to have to lip ring.
Professor Fred Watson: Okay. Uh,
so. Right. I'll do my best.
Andrew Dunkley: We'll see how that.
Professor Fred Watson: I'm wondering where the lips are going to be. That's the only thing.
Andrew Dunkley: Yes, yes. Well, the first set of lips come from
Paul. Uh, so let's hear his question.
Paul: G' day, Fred Watson, Andrew, Johnty,
Heidi, whoever happens to be at the helm. Uh, this
is Paul from Sunnybris, Vegas. Thanks, uh, for doing a
great job as always.
I have a quick question about surprise
black holes. Um, Dr. Shamir
put out a paper recently about
his ideas regarding the fact that, uh,
some galaxies are spinning one way and
uh, a lot of them, most of them the other way.
And another fellow chipped in, Nikodem Poplowski
from New Haven, suggested that
maybe that was because our universe was born inside a black
hole. If that is true, how the heck
did we get out? And if we
didn't get out and we're still inside,
then how is that possible given that, you know,
anything that goes inside a black hole, uh,
is spaghettified according to our current
thinking and therefore incoherent. I mean I know
I'm incoherent, but you know what I'm talking about. Talking about
when it comes to ordinary baryonic matter.
Uh, love to get your thoughts on this.
Anyway, uh, keep up the good work and
catch us later. Cheers.
Andrew Dunkley: Thank you Paul and hope all is well in Brisbane. Paul
is asking about the universe being born inside
a black hole. How do we get out? And why
don't we get spaghettified as a consequence
of that? Amongst many other things.
But uh, that was the basis of the question.
Professor Fred Watson: So. Yes. So as you've already uh, mentioned, I
didn't hear any of Paul's question there. Not at
all. However, I did listen uh, to it yesterday. So
I've got a bit of an idea of what Paul was suggesting. The
fact that um, we have uh,
new observations which uh, have
been made with the James Webb Space Telescope,
uh, that um, are
intriguing in the sense that uh,
these scientists, uh, and they
are basically uh, mostly
located at Kansas State University.
Uh, the, the rotation of galaxies in the
deep universe isn't random. Uh,
you'd expect, you know, galaxies to
be rotating in.
They can only go one way or the other. But you would expect
an equal balance of rotations.
Uh, and uh, what find, uh, or what
these scientists find at Kansas State
University using the James Webb
Space Telescope Advanced Deep Extra
galactic survey or jades, um, what
they find is out of 263
galaxies, um, which
you know, which give away their
rotation because we know that spiral arms nearly always
trail. There's at least one galaxy where the spiral arms are leading
but most of them trail. And what they
find is that out of these 263 galaxies,
about two thirds of them are going clockwise
and the rest are going anticlockwise. And that is an
imbalance. That's a statistically significant
imbalance, uh, that suggests that
something's going on that we don't understand and
that leads to the possibility
that perhaps the universe itself
is rotating. Um,
and I've seen other um, papers
um, on this topic that suggest that maybe the
universe rotates once in every 500 billion years.
That's one figure that I've seen
now, um, a consequence of the
rotating universe. And I think this is where Paul's
question went. I'm trying to remember having heard it
yesterday, uh, is that
it lend some weight to the
idea that the universe is
inside a black hole. Uh, in other
Words that there is an event horizon at some
huge distance from where we are,
uh, and we are all within this
black hole. Um,
what does that mean for observational
cosmology? I suspect it's going to be very
difficult for us to confirm
that ever. Uh, and I
think, um, you know, this is
speculative research. It's important
research because you, you, you want to know
um, how some of these things interact. And I might just
mention, and I think we've discussed this before, Andrew, on space
nuts, that the idea of a rotating universe
actually relieves some of the issues,
uh, that we find uh, in observing the
universe. One of them is the Hubble tension. And I know there's a question coming
up about that. Um, so a rotating
universe has certainly attractive possibilities, but
we absolutely don't know whether it is a
rotating universe and indeed whether that means that we're inside
a black hole. Uh, so what I was going to say was the idea of a
universe within a black hole is akin to the idea of
multiverses. The idea that um,
um, multiple universes exist and we
are just one of them. I'm not really, I
don't think giving a sensible answer to Paul's question,
partly because I couldn't hear it. But I think he was basically
asking, you know, what happens? How does it happen?
Uh, how are we not being spaghettified? That's
because, uh, I can tell you the answer to that. Uh,
we're not in a region, um, of the black hole
where the um,
gravitational pull is
changing very, very rapidly with space.
And that's what makes a black hole spaghettify. You, you go
from one point to another and your gravitational pull is very different.
So your head feels a different gravity from your feet and you get
spaghettified. We're not in a place where
that would be happening if we were inside a black
hole. But uh, you know, all bets are off because
inside a black hole, uh, there might.
We're in a different dimensional space. A black hole is a
singularity. Are, ah, we in a singularity? A singularity is
a point with no dimensions. Work that
one out. So we'd have to be almost in a different
dimensional space. So it's an interesting
question, um, to which I don't
think anybody knows the answer, but there are a few people who
are probably thinking through it a lot more clearly than I am.
Andrew Dunkley: Well, Paul mentioned uh, a physicist by the name of
Nicodem, um, Poplaus,
uh, he's one that's put this theory
forward that um, our
observable universe is not just a part of a
larger universe, but is in fact the interior of a
black hole within a larger context.
Professor Fred Watson: Yes. So you've got extra dimensions somewhere out there
within, uh, which we exist. Uh,
that's right. It's, um, uh, you know, I,
I, Yes, I remember, um, checking out the, the researchers
that, uh, that Paul mentioned yesterday when I looked at it.
Uh, it's interesting stuff. Yeah.
Andrew Dunkley: What do you think, personally? I mean, is there any
possibility that this could be
real?
Professor Fred Watson: Um, to me it's on the same level
as does heaven exist? Uh, you know,
it's questions to which we really can't
find answers. We can theorise, we can
conjecture, we can speculate, we can write equations
down. And probably some of the equations do support the
idea that we're within an event horizon. It
goes back a very long way. It's not a new idea at all.
Um, but, um, I mean, people have put new
numbers on it, I think, and, um, new observations. I think
we, we watch this space. Next time this question comes up,
I might be able to hear it properly and might be able to give a more
cogent answer.
Andrew Dunkley: Yes, indeed. I'll be working on that technicality.
Professor Fred Watson: I don't, I'm sure it's not your fault, Andrew. I know what these
gremlins are like. We get them all the time.
Andrew Dunkley: Yeah, I'll blame the equipment. Never ever, though.
Professor Fred Watson: Never the place. New Z. No, that's true.
Andrew Dunkley: Thank you, Paul. Hope we covered that adequately, as we strive
to do here on Space Nuts.
Professor Fred Watson: Space Nuts.
Andrew Dunkley: Uh, our next question, Fred Watson, comes from
Casey in Colorado. In fact, he has two.
Could you please explain the new theory of
gravity in simple terms? Does
it, uh, have any merit? And could you, uh, please
explain hubble tension and what it means for our
understanding of the universe?
Professor Fred Watson: Yes. Uh, so
that's the answer. The answer is yes. Yes, I can.
The new theory of gravity, which I like very much. Um,
this comes from scientists in Finland, which is a
place that I like very much as well.
Um, and it's what they've done,
you know, they've taken, um,
a step forward. And I'm
assuming this is the, uh, this is
indeed the, um, the, uh,
the, the new theory that case is speaking about,
because we get nearly one every week, a new theory of
gravity. But this is the latest one. Um,
it's, uh, as I said, it's from, uh, it's
from, uh, Finnish scientists, uh, at
Aalto, uh, University. Um,
so it's what they've done
is what Einstein tried to do for the last, for
30 years of his life. Uh, which
is to unify quantum field
theory and relativity.
And uh, that's an issue because uh, they
are incompatible at ah, the levels that we
try and look at them now. Um,
and so uh, to bring a
quantum theory of gravity into being
is a big step. So um, what do I
mean by, by bringing a theory into being? Well
we know that there are four fundamental
forces in nature. Uh, the strong
and weak nuclear forces,
electromagnetism and gravity. And the
first three of those have very,
very well established and well uh,
understood quantum theories. Um,
for example, we know that electromagnetism is propagated
by photons. We're talking about it all the time. So the
suspicion is that gravity uh, is propagated by
gravitons. But so far there's been no theory of what
gravitons might be like. So what these scientists
have done have developed a new
theory, uh, a new quantum theory of gravity.
Uh, and I'm actually going to once again ah, quote
from phys.org, very uh, nice account of
this, um, uh, which is
actually, I think it is part of the press release from
Aalto University in Finland. So I'm quoting
the university. Um, researchers at
Aalto University have developed a new theory, quantum theory of
gravity, which describes gravity in a way that
is compatible with the standard model of
particle physics, opening the door to an improved
understanding of how the universe began.
While the world of uh, quant
theoretical physics may seem remote from
applicable tech, the findings are remarkable. Modern
technology is built on such fundamental advances. For example the
GPS in your smartphone works thanks to
Einstein's theory of gravity. Uh, and then uh,
the article goes on to describe the theory
is published in uh, Research Reports on
Progress in Physics. Um,
and this is the quote that I wanted to make. This comes
from the lead uh, author of the paper.
Uh, and um,
um, basically they um,
they've got lovely Finnish names. That's why I'm stumbling. It's
Mikko Partanen, uh, who's the um,
lead author. Uh, and the quote
is as follows.
And this kind of puts it into perspective,
if that's the big word. If this
turns out to lead to a complete quantum
field theory of gravity, then eventually it will give
answers to the very difficult problems of understanding
singularities in black hole and black holes
and the Big Bang. A theory uh,
that coherently describes all fundamental forces
of nature is often called the Theory of Everything.
Uh, some fundamental questions of physics still
remain unanswered. For example, the present theories do not yet
explain why there is more matter than antimatter in the observable
universe. Uh, and what they've done is,
um, they've developed something called a gauge theory. And gauge
theories are a particular kind of theory about the way
particles interact with each other through a field.
Ah, like the Higgs field and the Higgs boson. Um,
so, uh, it's basically a
very nice a, ah, very nice account. I won't read
any more because, you know, gauge theories got
symmetries and things of that sort. Um,
it's, um, a nice account.
I recommend people have a look@the phys.org
uh, paper. Uh, uh, sorry, the
fizz.org article. Casey, I'd send you to that
as well to have a look. It's a very nice account of, of what's
happening. You may end up like me thinking I really
need to know a bit more about gauge theory before I can understand
this. Uh, but, uh, nevertheless,
you'll get, um, a good idea of what's going on, I think.
Andrew Dunkley: M. Okay.
Now, Casey also wanted you to
explain, if you could, Hubble tension.
Professor Fred Watson: Yeah, that's an easier one. And, uh, as we've
spoken about.
Andrew Dunkley: That's good.
Professor Fred Watson: As we've spoken about today, uh, that's one of
the things we might get rid of. Yes, Hubble tension is a lot easier than
gauge theory. Um, and what it amounts to is we've
got two ways of calculating
the current expansion of the universe.
Uh, one is by looking at
galaxies in our
vicinity, uh, and looking at the rate at
which they are speeding away from us.
They're moving away from us faster as their distance
increases. This is exactly the discovery that hubble made in
1929. And, uh,
gives us something we call the Hubble constant, which is
just the rate of expansion of the universe. Today we call
it, ah, h. Naught, um, Hubble
zero, which is the expansion rate today.
Now, you can also get an idea of that
or a measurement of it from the cosmic microwave
background radiation. And that, to recap, is
the flash of the Big Bang. We're looking back so far
in time. We're seeing back to a time 380,000 years after
the Big Bang, when the universe was still opaque and glowing brightly.
So we see this wall of radiation which is now in the
microwave region of the spectrum,
uh, and it's peppered with a pattern
of warmer and cooler places,
uh, and those, uh, zones
of higher and lower temperature, and it's only by a tiny
fraction, uh, they correspond to the
structure in that fireball. Um,
in fact, it's caused by sound waves moving through
it, they're called baryonic acoustic oscillations.
And we can, by measuring the properties of that
peppering of warmer and cooler regions,
we can actually work out what the
expansion of the universe is today. And
it turns out that the two figures are different,
um, by something like 4
or 5%. And that in
modern terms is big enough to worry about. It's
not just an error of measurement. Uh,
these have got fairly tight limits on the
uncertainties, but they're different. And that is the
Hubble tension. Hm.
Andrew Dunkley: But didn't they recently, recently
release a paper that suggested that the variations
are actually within a normal range? That this,
this, these two
figures that don't match are, ah, close
enough?
Professor Fred Watson: Well, yes.
Andrew Dunkley: Didn't we talk?
Professor Fred Watson: We did that. Um, some people have suggested that, that it is,
that it is actually within the experimental
uncertainty, but it's still seen as attention. They
could, they should be nearer than what they are.
Andrew Dunkley: Yeah, okay. Very, very interesting,
Casey. Thanks for both your questions. And no, you haven't
spammed us. Two questions doesn't equal spam.
There's probably a definition somewhere online that says how many,
how many emails become spam.
You're well, well outside that tolerance. So no
problem there. Uh, this is Space Nuts
Q A edition with Andrew Dunkley and Professor
Fred Watson Watson.
Space Nuts. Okay, Fred Watson, let's uh, move
on to our next question. It's an audio question so
you won't be able to hear it, but it comes
from Simon.
Simon: Hi, it's uh, Simon from Vasey in
New South Wales here. Uh, my question's around,
uh, the search for Planet Nine,
uh, other exoplanets. Ah, few have been found
using radial velocity methods. Is
that something we could do with the sun?
Um, I guess Planet nine being so far
out, probably wouldn't have much influence,
but we would have so much data on the
sun as well
that it might be easy to suss out.
Anyway, Ah, that's my question.
Andrew Dunkley: Thank you, Simon. Good to hear from you. Hope all is
well in Veyce in New South Wales. Uh, he's
asking, in the search for Planet nine, um,
we've used the radial velocity method, uh,
in the past to find other objects. Could, uh,
we use the sun in the search for
Planet Nine?
Professor Fred Watson: Yeah, and it's a great question. Uh, I'm
very well posed, Simon. Uh, I did actually manage
to hear that through my own, um, recording,
which I found and listened back to. So I know what
Simon asked. And
what he's saying is that we know that when
we look for exoplanets, planets around,
uh, other stars. What we look for is the change in position
of the star itself as it's pulled one way
and another by the planet orbiting around it.
And yes, indeed, the solar system,
uh, has such an effect. So
Jupiter principally is the main planet
that's pulling the sun's centre
one way or the other. Uh, but the other planets all
intervene as well. And so what we
have is something that's called the solar system's
barycenter, the centre of mass
of the solar system and that moves as the
planets wander around. And,
um, we've exactly as, um,
Simon says, we've managed
to work out the position of the
barycenter very, very accurately,
uh, partly because we know where the planets are and
things of that sort of. Now,
Simon's question is
actually exactly the same as a
question that I found on Stack Exchange Online.
The question was, wow, can the paper
narrowing the solar system's barycenter to within
100 metres help find Planet Nine?
Uh, so that's basically what Simon asked. And
the bottom line, there's a long, long
set of calculations here which I won't
go through, but the answer is probably
not. Um, uh, it's because
the Planet
nine's influence on the solar system's
barycenter, it's helped by the fact that Planet nine's
a long way away. Um, um, so it's got
sort of leverage, uh, as it goes around.
Um, um,
the short answer is
maybe we could do it, but we wouldn't be
able to do it without hundreds, if not
thousands of years of precise data. And
that's because Planet nine is probably orbiting the
sun on that kind of timescale. And
so you don't see any, you know, what you'd be looking for
is, um, changes in the position
of the barycenter, which are not caused by the
known planets. But it'll take you
hundreds or thousands of years to see that because of
the great distance that Planet nine is at.
So the answer is probably not, but it's a great question
and really nice thinking. I like Simon's thinking there.
Andrew Dunkley: Yeah, yeah, it's quite astute. Uh, the
other factor that comes into play here is
the new theory that Planet nine doesn't
exist because there's another planet even further
out that, uh, has only
just been sort of put into, um, a
pager and open for discussion. So we only
talked about that last week. So the search for
Planet nine might be a forlorn hope anyway, uh,
um, because it probably, according to the new
theory that's correct.
Professor Fred Watson: Yeah. Now, the new theory is based more on observations
than theory because it's two
observations separated by something like 30 years that seem to
show something moving very slowly in the outer solar system.
You can bet your life will do more observing of that over, uh,
uh, coming decades. Uh, and
maybe that will turn out to be what I think is being called Planet
eight and a half at the moment, because nobody really knows whether it's
there or not. But as you said, if that is
real, it rules out Planet nine. The two can't exist
together.
Andrew Dunkley: Exactly right. All right, there you go, Simon.
Um, we'll see where that, uh, ends up, but
it might take a while.
Uh, final question comes from Joe
in Olala in Washington. I hope I pronounced that
correctly. Is there an upper limit to how much
Delta V, uh, that can be practically
generated by gravitational assists? Is it possible
to develop sufficient Delta V for
timely interstellar travel by winding up a probe in
our solar system before launching it, uh, to a
nearby star? Uh, thanks for all that you do.
Cheers, Joe. Now, Delta V, that is the
impulse per unit of spacecraft mass,
yes?
Professor Fred Watson: Well, it's basically the change in velocity.
Um, yes. And impulse is the, uh, that's the way people
talk about these Delta V's in this, in the rocket
industry. It's all rocket science. What is it
anyway, Delta V, uh, I think in
Joe's context here is how much
velocity increase you can get from a
gravity assist, from a, ah, slingshot.
Uh, and the answer is probably no, um,
in terms of trying to wind up, you know, the speed
of things so that you, you know, you
tell something out of the solar system at
10th, uh, the speed of light or something like that.
Um, the reading that I've done on this, and
I did check it out seems, uh, to suggest,
excuse me, that um, we are probably
limited to,
um, the sorts of velocities that we
see among the planets of the solar
system. Now remember, the Earth is orbiting
the sun at 30 kilometres per second.
Um, and, um, those velocities
get less as you get farther away from the sun. And
that's part of the equation with a slingsot, because what you're
trying to do is steal some momentum from the planet and,
and give it to the spacecraft. And so there are upper
limits, uh, on, um, what sort of velocity
change you can get. It depends on how close
you go to the planet, depends whether the planet's got an atmosphere or
not. It, uh, depends on the angle that you come in. Um,
the figure that I've seen quoted As a maximum
for Jupiter, which is the most effective planet for this sort
of thing, being by far the most massive planet in the solar system,
is a change of 40 kilometres per second.
Um, now that's very good if you're
you know, trying to get something out to the outer solar system,
but it's not going to help you getting things
to other planets. Especially when you think,
you know, if you give uh, a planet,
sorry a spacecraft, an impulse
Delta V of 40 kilometres per second by interacting with
Jupiter, you've got to then find
another planet that's, that's going to give
it even more. But the other planets are all moving slower than
that so uh, the change in
momentum is a lot harder to get. Uh,
so I think the answer is it's a very nice idea. As
Joe suggests, winding up by all these gravitational
interactions, you can only do it within
limits. You're not going to be able to get
like 100,000 kilometres per second or something like that
from doing that.
Andrew Dunkley: Yeah, I suppose you could equate it to using
a slingshot or a shanghai. There's only so much
tension you can push, put in, into the, the rubber band,
let's say to fire the rock. And you're not going to be able to
fire the rock any faster than the
maximum amount of storage the rubber band can hold.
And I'm guessing it's the same.
Professor Fred Watson: Yes, there's a, there's a limited amount of energy
that you can get from, from a slingshot. That's right,
yeah. Nice idea there.
Andrew Dunkley: Although it's, it's been very effective as you
said, for sending things to the outer solar system.
The, the Voyager probes particularly
uh, used um, the slingshot effect,
um, several times to get to
the outer solar system because they didn't have the fuel to do it.
So they figured out through um,
an alignment of the planets that they
could get out there just by using
the rotation of the planets or um,
the process uh, that uh, uh,
Joe's been talking about. So um, yeah it does
work quite effectively for slower,
slower speeds that uh, yeah,
interstellar, probably beyond us in that
regard.
Professor Fred Watson: Yeah, probably the lasers and um,
you know in a solar cell or a light sail might be a
better bet. But even that beyond our technology
at the moment.
Andrew Dunkley: Um, probably won't be for long though. I think they'll develop
that and get some spacecraft
heading out towards the Alpha Centauri sector and
um, anyway that remains to be seen. Uh,
but that would still be a pretty slow mission in the scheme of things.
But um, yeah, great question Joe,
thanks for sending it in. And if you'd like to send us a
question, uh, you can do that, uh, through
our website, spacenutspodcast.com
spacenuts IO. Click on the AMA
link at the top and you can send us text and
audio questions. And don't forget to tell us
who you are and where you're from. We love to know that sort of stuff so that we
can send the boys around. Or, uh, we could send
Huw around because he can't be with us today, so he must be
visiting one of you guys, um, with his, with his,
um, you know, balaclava on, maybe.
Yeah.
Professor Fred Watson: Thank, um, you, Fred Watson, as always, a pleasure. Andrew, as
always. Good to talk and uh, good to hear our
listeners questions. It's.
Andrew Dunkley: It is, it is. All right, well catch you again
real soon. Professor Fred Watson Watson, astronomer at large, and from me,
Andrew Dunkley. Thanks for your company. See you on the next
episode of Space Nuts. Bye for now.
Professor Fred Watson: You've been listening to the Space Nuts.
Andrew Dunkley: Podcast, available at
Apple Podcasts, Spotify,
iHeartRadio or your favourite podcast
player. You can also stream on
demand@bytes.com. um, this has been another
quality podcast production from Bytes.
Professor Fred Watson: Com.