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Cosmic Queries: White Holes, Dark Matter & the Universe's Mysteries · Space Nuts: Astronomy Insights & Cosmic Discoveries

0:00
Heidi Campo: Welcome back to another fun and exciting
0:02
Q and A episode of space nuts.
0:05
Voice Over Guy: 15 seconds. Guidance is internal.
0:08
10, 9. Ignition
0:10
sequence start. Space nuts. 5, 4, 3,
0:13
2, 1. 3, 3, 4, 5, 5, 4,
0:16
3, 2', 1. Space nuts. Astronauts
0:19
report it feels good.
0:21
Heidi Campo: I am your temporary host, Heidi,
0:24
joining you today with Professor Fred Watson,
0:27
astronomer at large, while our
0:30
usual host, Andrew Dunkley, is off on his
0:32
world cruise, having a grand old time.
0:36
Ah, Fred, how are you doing today?
0:38
Professor Fred Watson: I'm very well, thank you. Um, ah, still
0:40
inundated with people interested in the end
0:43
of the universe, which we talked about a few
0:46
episodes ago. Uh, so that's good to know
0:49
that, um, uh, people are taking some notice
0:51
of the fact that 20 billion years might be
0:54
the, uh, closing down ceremony for the
0:57
universe. We'll cover that in Space Nuts.
0:59
Heidi Campo: Obviously we'll talk about the end
1:02
of the universe.
1:03
Well, today, um, we've got more great
1:06
questions. I always say that our questions
1:08
are what makes up half the show? And our very
1:11
first question of our episode
1:14
today comes from Casey. From my side
1:16
of the world, from Colorado, which is a
1:19
beautiful state. And I always tell people if
1:22
you see beautiful pictures of the mountains,
1:24
they're definitely from Colorado, not from
1:26
Utah. Utah's full. Don't go.
1:30
So Casey from Colorado says,
1:33
hi, guys. I know that white holes are
1:35
basically the opposite of black in the way
1:38
that nothing can enter them. I understand
1:41
that at this point they are completely
1:43
theoretical and we haven't actually found
1:45
any. If we did find one, what
1:48
would be inside of it? Would it have mass?
1:51
How does gravity work in and around it? Love
1:54
the show and hope you're both well. Thanks.
1:57
Professor Fred Watson: That's great. Thanks. Thanks. Thanks very
1:59
much, Casey. And, uh, it's a good question.
2:02
Um, uh, it's probably about 30 years
2:05
ago that white holes were all the rage.
2:07
People were talking about them endlessly.
2:11
Uh, and, uh, I guess what that did
2:14
was set up people looking for them. And we've
2:16
never found any, any evidence of one. Uh, but
2:19
the reason why people think that they might
2:22
exist is that there's nothing
2:25
in the equations of relativity,
2:28
which is what govern the behavior of black
2:30
holes and space. And generally. It's
2:33
Einstein's theory of gravity. Uh, there's
2:36
nothing in that that says that you can't
2:38
have, uh, a sort of opposite object
2:41
to a black hole. And what you have to
2:44
do in the equations is reverse the direction
2:46
that time works in. Uh, and if you
2:49
switch that round and yes, that's hard to get
2:52
your head around at all. But if you do
2:54
that, put negative time in instead of a black
2:57
hole, you get a white hole. Uh, and so
3:00
the theoretical physicists said there's
3:03
nothing that we can find that would
3:06
rule out the existence of these objects, that
3:09
they, they may exist. And then
3:12
there was the connection that perhaps two
3:15
black holes or two white holes, or a black
3:17
hole and a white hole could, could connect
3:19
with each other to make a wormhole, which
3:21
might give us a way of getting from one side
3:23
of the universe to the other very quickly.
3:25
Um, I think you'd risk all kinds of horrible
3:27
things happening if you did that. But anyway,
3:29
uh, that's the idea. So, uh, the quest
3:32
was on, uh, for uh, you
3:35
know, looking for evidence of white holes,
3:37
which you would think,
3:40
unlike a black hole, would be very bright.
3:42
Uh, and um, so far we
3:45
found nothing, no evidence of anything
3:48
that would correlate with the, you
3:51
know, the um, observations that
3:54
physicists, um, suggest might be made of a,
3:56
uh, of a, of a white hole. Um, if we
3:59
did find one, as, as Casey asks, uh,
4:02
what would be inside it? Well, yeah, it's
4:05
hard to know, uh, because, you know, black
4:08
holes, it's a one way process for stuff going
4:10
in. Uh, with a white hole, as you say,
4:13
Casey, it's a one way process with stuff
4:15
coming out. Uh, so where's that stuff come
4:18
from? What's inside it? Where has
4:21
the material that might
4:23
be escaping from it? If it was, uh,
4:27
where did that, where did that come from?
4:30
Maybe from a wormhole, maybe just from
4:32
sucking it in from the fabric of space. Um,
4:35
I'm not qualified enough in relativistic
4:38
theory to be able to give you an answer to
4:40
that. Um, would it have mass? Yes, I think it
4:42
would. Um, I think the mass
4:45
is one of the constants in the equations
4:48
of the white hole. So I think the answer is
4:51
it would have mass and so gravity would
4:53
probably work around it in the same way
4:56
as a black hole does. I'm sort of speculating
4:59
here, Casey. Uh, these are not authoritative
5:01
answers because I have, have not had a look
5:04
at the white hole theory for a long time.
5:07
But I think you can draw all kinds of
5:09
comparisons. It's a, there's an analog,
5:12
you know, from, from a black hole to a white
5:14
hole. Uh, the fact that we've never found
5:17
anything that has symptomatic, uh, or is
5:20
symptomatic of the existence of a white hole
5:22
probably means that in reality they don't
5:24
exist. Um, but we're always open to
5:27
suggestions.
5:29
Heidi Campo: We could just be in the wrong universe for
5:31
them.
5:32
Professor Fred Watson: That's true. Uh, in a different universe,
5:34
maybe white Holes are everywhere. Yes, quite
5:36
so.
5:37
Heidi Campo: And they can't find any black holes. There's
5:39
some podcast where there's a
5:42
Fred interviewing a Fred's interviewing
5:44
Heidi and they're wondering, well, why can't
5:46
we find these theoretical black holes?
5:48
Professor Fred Watson: Yeah, that's right. And time's running
5:50
backwards for us.
5:52
Heidi Campo: Yeah, uh, we're getting younger.
5:55
Professor Fred Watson: That'd be good.
5:57
Heidi Campo: Our next question, um, you must have listened
5:59
to a few episodes ago where we were talking
6:01
about name history. Um, this is from
6:04
Martin. Martin says hi
6:07
Adelheid and Frederick. I
6:09
just listened to your latest episode Stellar
6:12
Questions and um, the very first one puzzled
6:14
me. This is about time dilation.
6:17
The formula Fred used for calculations
6:20
takes into account only velocity.
6:23
Isn't it only for observation dilation.
6:26
The reason it puzzles me is that the scenario
6:28
was traveler returns back to Earth.
6:31
Isn't that more like twin paradox?
6:34
And the differences should be explained by
6:37
acceleration because without acceleration
6:40
and given the velocity is relative, we
6:42
couldn't tell if it was the astronaut who
6:45
traveled or the Earth who went for a trip and
6:47
returned to a, uh, stationary protagonist.
6:50
I hope I'm not completely off. Great work
6:53
with the podcast, I love it.
6:56
Professor Fred Watson: And Martin, great work on the question
6:58
because everything you've said is absolutely
7:00
correct. Um, I just didn't say all that
7:02
because didn't seem as though there was time
7:04
to do it. But yeah, um, you're right. Um,
7:07
um, you've got to have for the twins paradox
7:10
to work. And that's where one twin goes off
7:13
on a long journey into space very quickly at
7:15
what was it, 99.99995% of the
7:18
speed of light. If you want to have a 100
7:21
year ratio or 100 to 1 ratio,
7:24
uh, um, the astronaut goes
7:27
off, uh, uh, visits a
7:30
distant star, takes their photographs
7:33
and with their smartphone and all the rest of
7:35
it comes back to Earth. Uh, the
7:37
Earth has aged by 100 years and the astronaut
7:40
has only aged by a year. Um, that's called
7:43
the twins paradox because you imagine that
7:45
it's would be two twins who were being
7:48
separated like that. Uh, and
7:51
it only works because of
7:55
the accelerative component. So uh, the
7:58
answer I gave was purely special
8:01
relativity. That's simply, um,
8:04
you know, relativity, uh, with
8:06
motion at a constant speed.
8:09
Uh, so clearly you're not going at a constant
8:11
speed. If you turn around and come back
8:12
again, uh, you've got a deceleration and then
8:15
an acceleration. And those are the terms that
8:18
allow the twins paradox to work. It's the
8:20
fact that you're actually switching
8:22
acceleration because that introduces, uh,
8:25
geometrical, uh, elements which are
8:28
more related to general
8:30
relativity. And in fact, um, what
8:33
I also didn't mention, um, so just
8:36
to, um, fill you in, Martin, that,
8:39
uh, there is more to the story. Exactly as
8:40
you've said, uh, in general relativity,
8:43
that's Einstein's second theory of
8:45
relativity, the one that accounts for gravity
8:48
and that lets black holes exist and white
8:50
holes and all the rest of it. Um, that
8:53
theory also has time dilation in it. In
8:56
other words, uh, what it says is that if you
8:59
get in a strong gravitational field, your
9:01
clocks run more slowly as observed from
9:04
outside than they would
9:07
if you were just outside, uh, the
9:09
gravitational field. So, for example, our
9:11
clocks are running slightly more slowly than
9:14
clocks on board spacecraft, uh, orbiting
9:16
the Earth. And that has been measured, that
9:18
time dilation has been measured. And I think
9:21
it is taken into account in the
9:24
GPS in your phones as well. I think you have
9:27
to have those relativistic corrections in
9:28
there for it to work. So. Yes. Good
9:31
pickup. Thank you very much, uh, Martin.
9:34
Uh, and, um, thanks also for giving my Sunday
9:37
Best name as well. Uh, very few people call
9:39
me Frederic. It's usually people in banks or
9:42
in medical reception areas
9:45
because that's my full name. Is your full
9:47
name Adelheid? Heidi?
9:49
Heidi Campo: My full name is Heidi, but the, uh, name
9:51
comes from Adelheid, um,
9:54
which I believe means noble
9:57
is the kind of the history of the name.
10:01
Um, but I know it's a German name. I know
10:04
my mother read the book Heidi when she was
10:06
young and she loved the character. So that's
10:09
how I got the name Heidi. Despite. I'm
10:11
actually, um, my, my family heritage is
10:13
Italian. I'm, I'm second generation
10:16
Sicilian. So I still have family in Sicily,
10:19
but I have a German first name, an Italian
10:22
last name and an Irish husband. So I'm a, uh,
10:25
classic American, you can say.
10:26
Professor Fred Watson: Yeah, that's good.
10:32
Heidi Campo: Space nuts.
10:33
Our next question is, uh, from
10:36
Ash from Bris Brisbane. And
10:39
Ash says, hi, Heidi and Fred. I hope this
10:42
message finds you well. I recently came
10:44
across a statement by Professor Brian Greene
10:47
regarding the observable universe
10:50
being 93 billion light years across.
10:53
He mentioned that if we were to condense the
10:56
known mass of the observable universe into
10:59
theoretical black hole, the
11:01
calculations suggest that the event horizon
11:03
would align with the distance of the
11:06
cosmic microwave background.
11:09
This leads me to wonder, is Roger Penrose
11:11
correct in his theories? Could the cmb,
11:15
the cosmic microwave background, actually
11:17
represent the inside of an event
11:19
horizon? And that's why we cannot
11:22
penetrate it? Is this just One big
11:25
universe sized coincidence. I'm
11:28
looking forward to hearing your thoughts on
11:29
this intriguing topic.
11:33
Professor Fred Watson: That's great. Thanks for that, Ash. Uh, um,
11:35
we did talk about the idea, uh, of the
11:38
universe being a black hole or inside a black
11:41
hole, I, uh, think in the last Q and A
11:43
episode. But I was talking last night to some
11:46
of my colleagues at the conference that I'm
11:47
at at the moment, Astronomical Society of
11:49
Australia's annual science meeting about
11:52
this, um, and um, I think
11:56
the general
11:58
opinion was
12:01
basically what you've said, Ash, at the end
12:04
of your question there. Is this just
12:06
one big universe sized coincidence?
12:09
I think, uh, everybody thinks that,
12:12
um, it's drawing a long bow
12:15
to assume that we might be inside a
12:18
black hole, uh,
12:21
only by the fact that the universe,
12:26
effectively what we call the proper distance
12:28
to the event, sorry, the cosmic microwave
12:30
background radiation would be about the size
12:33
of the event horizon, uh, if the mass
12:36
of the observable universe was in a black
12:38
hole. So, uh, that's one strand
12:41
to this, but you've highlighted another one
12:43
as well. As with Roger Penrose, his ideas are
12:46
very much concerned with, um, big
12:49
bangs coming from black holes
12:52
detonating in a universe that just keeps
12:55
on going. So we've got this multiple multi
12:57
universe idea again, the multiverse with
13:01
supermassive, uh, black holes or hyper
13:03
massive black holes popping off everywhere.
13:05
And each one forms its own universe, uh,
13:08
inside it, and we're inside one of those.
13:10
It's a nice theory. Again,
13:14
very, uh, speculative. There's no
13:16
evidence to, in fact, it's hard to
13:19
imagine what the evidence might be to prove
13:22
that. We have people working on
13:24
the idea of multiverses and indeed
13:28
the Penrose theories as well. Um, but it's
13:30
very hard to think what evidence you might
13:33
bring to bear on that that says yes or no,
13:36
uh, about living in a black hole. Um, it's a
13:39
nice coincidence though, this, uh, you know,
13:41
the radius of the universe being
13:43
approximately the radius of the event horizon
13:45
of a black hole. I think that's all it is,
13:48
though.
13:48
Heidi Campo: We may never know.
13:50
Professor Fred Watson: We may never know. That's right.
13:55
0G. And I feel fine.
13:57
Heidi Campo: Space nuts.
13:58
Well, what I do know is that our last
14:00
question of the day is from one of our
14:02
regular listener listeners. I can
14:05
still talk. I haven't gotten fatigued. I
14:07
usually get a couple audio questions mixed
14:09
in. That's all these written questions. I'm
14:12
doing more talking, but I can still say that
14:14
our last question is from Rennie Trabb from
14:16
Sunny Hills West, California. Sunny
14:19
West Hills, California. Maybe I losing my
14:22
Ability to talk. But it's good because this
14:24
is a short question and Rennie says it
14:26
seems that there is a purpose for why the
14:29
universe is the way it is. What are your
14:31
thoughts on why dark matter functions the way
14:34
it does and the need for it to not
14:36
react with the light, but, but yet it reacts
14:39
to our matter in the universe?
14:42
Professor Fred Watson: Yeah, uh, I mean, this is a really deep,
14:45
deep question, uh, which is sort
14:48
of concealed in some, you know,
14:51
very innocent language. I think it's a
14:53
beautiful question, Rennie, as yours always
14:56
are. Um, so that,
14:59
that first sentence, it seems there is a
15:01
purpose for why the universe is the way it
15:03
is. Um, I think the way I
15:05
would look at that, uh, is the
15:08
other way around. That, uh,
15:17
it's something called the, uh, strong
15:19
anthropic principle that says
15:22
that, uh, we can
15:25
observe the universe because we
15:28
are here. It's a, you know, it's
15:31
almost like a non sequitur, something that
15:33
just doesn't follow. Uh, but what it's saying
15:36
is that we are here
15:39
because the universe has certain
15:42
physical properties. And it's the laws of
15:45
physics that let stars form, galaxies
15:48
form, planets form. You know,
15:51
humans form all the rest of it. Uh, that
15:54
is, um, to say that
15:57
it looks as though we live in a universe that
15:59
is fine tuned for life. That if these
16:02
physical, uh, constants were
16:05
different, particularly if the speed of light
16:06
was different or the charge on the electron
16:08
was different or whatever, uh, the universe
16:11
might never have been able to form planets.
16:13
It might have either been so short that it
16:16
collapsed on itself almost immediately, uh,
16:18
or it may have been so
16:21
rarefied that atoms never came together to
16:24
react and form molecules and make up the
16:26
ingredients for life. So it's this fine
16:29
tuning, as I said, it's the anthropic
16:31
principle. Um, and so in a way
16:34
you can interpret that is as the universe
16:37
having. Let me just read your sentence again.
16:40
A purpose for why the universe is the way it
16:42
is. Uh, its purpose is
16:45
perhaps a strong word, but, um, it's saying
16:48
the universe is the way it is. It
16:51
allows us to be in it. If there was a
16:53
different universe that we're in, we wouldn't
16:55
be here, so we wouldn't be able to observe
16:57
it. Uh, so I think that's a
17:00
fascinating question. It's one that's been
17:02
written about a lot. Uh, the anthropic
17:04
principle.
17:05
Um, what are my thoughts on why dark matter
17:08
functions the way it does and the need for it
17:10
not to react with light, but yet it reacts to
17:12
our matter in the universe? Look, that's just
17:15
a huge mystery, um, that
17:18
um, we have this, these
17:20
observations that suggest that there is
17:22
something in the universe that has
17:24
gravitational, uh, attraction.
17:26
It attracts things. It's
17:29
got enough gravity that it stops galaxies
17:32
from flying apart because their rotation's
17:34
too high. Uh, and yet
17:37
it does not interact in any way
17:41
in any of the other properties. So it
17:43
doesn't, uh, have any reaction, as
17:46
you say, with light, electromagnetic
17:48
radiation. So for example, it doesn't block
17:50
out the light. Light coming behind it would
17:53
be very handy if it did. Then we could
17:55
actually see it and measure its properties.
17:57
Um, what we have to do is look at the
18:00
way, uh, it does interact with light, which
18:03
is through gravity. Uh, that means, uh,
18:07
it can act as a lens. If you've got a large
18:08
blob of dark matter, it can act as a
18:11
gravitational lens, which means it will focus
18:13
light and let us see magnified images of very
18:15
distant galaxies if you've got a large blob
18:18
of dark matter around a cluster of galaxies
18:21
in the foreground. Because we do know that
18:23
dark matter is where normal matter is.
18:26
Wherever there's normal matter, there is dark
18:28
matter, except in a very few cases.
18:31
So, uh, yeah, it's still a mystery and it
18:34
is still possible, um, uh,
18:38
that we've got it wrong, that
18:41
there is something else going on, uh, that
18:44
that negates the need to have dark matter
18:48
as a property of the universe. And one of
18:50
those things is something studied by a friend
18:53
and colleague of mine, Peter Verwein. He's
18:55
uh, still, I think, writing his PhD thesis
18:58
on a theory called MON Modified, um,
19:01
Newtonian dynamics, uh, which
19:04
suggests that, uh, at very low
19:06
accelerations, uh, which are the kind that
19:09
are experienced by stars going in
19:12
orbit around the center of a galaxy, for
19:14
example, at very low accelerations, our, uh,
19:17
normal understanding of Newtonian physics
19:20
breaks down. So MOND is Modified Newtonian
19:22
Dynamics, uh, and it was introduced
19:25
back in the 1980s when dark energy was first
19:28
postulated by a scientist,
19:31
uh, whose name was Mordechai Milgrom. Uh, he
19:34
introduced the idea and it's been floating
19:36
around ever since. M why isn't it accepted
19:39
generally as the main reason why the galaxy
19:42
behaves like it does and why the universe as
19:44
a whole behaves like it does? Uh, that's
19:46
because, um, if you tinker around with
19:49
Newtonian dynamics, a lot of other things
19:51
don't make sense. Uh, the early universe
19:53
doesn't make sense. Globular clusters don't
19:55
make sense. And so that's why it's not
19:57
popular. Uh, but it's still possible that we
20:00
might be missing something. Maybe there is
20:02
something out there that makes us think
20:05
we're surrounded by dark matter and we're
20:07
not. So, uh, scientists have to be open
20:10
minded about that. Uh, not so open minded
20:12
that your brains fall out, as somebody once
20:14
said. Uh, but open minded enough that you can
20:16
recognize any possibility. And I think that's
20:19
really what, what my thoughts would be
20:22
in the questions that you've asked Rennie.
20:23
And thanks again for very profound and
20:26
thought provoking questions.
20:29
Heidi Campo: You guys did a great job with your questions
20:31
this week and Fred did a great job as always
20:34
answering them and I am just so grateful
20:37
to be a part of this journey.
20:39
Fred, um, do you have any, um, we got,
20:42
you know, maybe we can give another minute.
20:45
Do you have anything that you really have
20:46
enjoyed from this conference that's been like
20:49
some of your highlights?
20:51
Professor Fred Watson: Yeah. So, uh, the session that um,
20:54
I was really keen to be at was
20:57
yesterday. And it's about the
21:00
things that I lose sleep over. Uh,
21:03
how is Australia going to, uh,
21:05
be involved with the next generation of large
21:07
telescopes, large visible light telescopes?
21:10
These are things that um, might seem a bit
21:13
pedestrian when you compare it with the other
21:15
stuff that's going on at a conference. Uh,
21:17
there's a lot of really interesting new
21:20
science coming out. And one of
21:23
them that I sort of seem to pick up a lot
21:25
on is the idea of how, how galaxies
21:28
work, how the um, the
21:31
outflows of gas from their black holes at the
21:33
center. This is particularly in the early
21:35
universe, how that uh, can interact with
21:38
the gases that are forming stars. Uh, there's
21:41
a process called quenching, which is where
21:43
these winds that are blown out by black holes
21:46
actually blow out the star formation
21:49
process. So, uh, you get the star formation
21:52
process quenched. And that's something that
21:54
still has a lot of research going on with it.
21:56
That was certainly one of the hot topics
21:58
yesterday. Uh, but um, my
22:00
fascination is always with, uh, because
22:03
basically I'm a telescope man. Uh, it's what
22:06
I did all my life. I ran telescopes, uh, for
22:09
a lot of my life. Uh, and I'm always
22:11
interested in where our country is going in
22:14
regard to the facilities that it needs so our
22:16
astronomers can make these discoveries of the
22:19
kind that we've been talking about today. Um,
22:22
so that was, I think, the highlight of the
22:24
conference for me. Um, some of the news is
22:27
good, some of it's not so good. Uh, of course
22:30
all facilities for astronomy rely on funding
22:32
and it tends to be governments that do that
22:34
funding because many of the arrangements are
22:37
bound by international treaties, which have
22:39
to be signed by governments and not private
22:41
individuals. So we will see where this
22:44
all goes. And, um, certainly on Space Nuts,
22:47
uh, we will keep everybody well aware of
22:49
what's happening in the world of telescopes
22:51
and the world of astronomy generally.
22:54
Heidi Campo: Thank you so much, Fred. Uh, it's been a
22:57
pleasure chatting with you today, and thank
22:59
you again to all of our listeners. And with
23:01
that, we are going to wrap it up and say good
23:04
night till the next time.
23:06
Professor Fred Watson: Good night and good morning.
23:09
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23:11
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