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the episode. Why? They thanks

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for joining us. This is space

0:20

nuts. The Astronomy and Space Science

0:22

podcast my name is Andrew done

0:24

by your host coming up. We

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will be talking about lots and

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lots of things because this is

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all audience Questions Episode: Ah so

0:32

this is where we throw it

0:34

over to you and you throw

0:36

a lot of stuff at Fred

0:38

and see if it sticks. We'll

0:40

be talking about fast blue transients,

0:43

the cooling universe and gravitons amongst

0:45

other things that ghost galaxies. The

0:48

heaviest isotopes in planet formation and

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so much more coming up on

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this episode. Allspice. Nuts.

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Damn. Channel.

0:59

Nine English Language.

1:01

Space next. To.

1:07

Space Nice. Meal.

1:11

And to answer all of your

1:14

questions with precision and perfection is

1:16

Professor Fred. What's an astronomer large?

1:18

Hello for it. Hello Andrew, How

1:20

are you do if I'm feeling

1:22

a lot better than you. Should,

1:25

it's like an exam. He knows some

1:27

discover like going into an exam that

1:30

you haven't studied for a thought. I

1:32

did that a lot. I did that

1:34

a lot. did. To second Science mathematics

1:36

of the universities and Andrews nearly got me

1:39

a in there and in the end up

1:41

busted by the skin and until. The.

1:43

Early. And. I wasn't so lucky

1:45

and a lot of my exams with In

1:47

Up my did it to myself. I look

1:50

back at my younger self and say you

1:52

Buffett the whole oh yes, that mean that's

1:54

absolutely right here with me that you wish

1:56

you could have a time mirror away, could

1:58

just go and sort of. To

2:00

the youngest he younger self appears in

2:02

you go With it since that's little

2:05

girl he has a degree of the

2:07

second. I'd

2:09

certainly. Yeah, I'm thinking of

2:11

writing a book about that has she was in a

2:13

subset that it make a great science fiction novel was

2:15

probably or up and done. In Moon

2:18

or Ice, we better get into

2:20

it now. Wow! We've got some

2:22

audio questions with us and text

2:24

questions are these are all pretty

2:27

well Brand new, ease and we

2:29

will start with a question from

2:31

Derricks. Hello!

2:33

Andrew, Professor Potts and my name is

2:35

Derek from Kids Your Ontario Canada long

2:38

time listener first time plus you. Have

2:41

a question regarding the cause of

2:43

past blue optical transients explosions. Particular

2:45

one called a T Twenty Eight

2:48

Team Cow Nicknamed the Cow. Discuss

2:51

in a previous episode, the solar

2:53

system sized explosion was considered odd

2:55

dude with being extremely flattened out

2:57

like a pancake rather than a

2:59

typical sphere. That the

3:01

slot and seats because by extremely

3:03

rapid spin say by neutron star.

3:06

Or. Perhaps to object spinning up until they're

3:08

torn to pieces? Thanks. To the

3:10

great podcast and bucks. I'm currently halfway through

3:13

stark raving mad. There. And

3:16

eat that. they supposed to do it.

3:21

Is so under to it was set up.

3:24

A year. The best thing about

3:26

that book is his title which

3:28

I didn't think of is earning

3:30

source of stuff raven Net and

3:32

entering tell from a troubling astronomer.

3:34

That's what these days like a

3:36

lot with a from my lovely

3:38

to hear from Canada as well.

3:40

Thanks her around sending you questioning

3:42

Derek Fast blue transients here. We

3:44

did talk about that recently and

3:46

this this disc shaped explosion that

3:48

done this defied logic. Or

3:51

death as he got the answer. or

3:53

well actually i think i think come the

3:55

house i was just gonna say the answer

3:58

today's question is yes some other I think

4:00

both the things that

4:05

he highlights, the possibility of

4:08

it being a rapid spinner or

4:11

being something that's disintegrating, both

4:14

of those could be

4:16

correct. I've got to remind myself actually

4:18

of the details of that.

4:21

I know we did talk about it, but to be honest,

4:25

these things come and go

4:27

so quickly that I've only

4:30

got half a gig left of memory in

4:32

my head that's not really enough for all

4:34

these facts. It's

4:38

an object that is probably

4:40

about 200 million light years away because

4:43

it sits in a

4:45

galaxy, especially coincident with that

4:47

galaxy, CGCG 137068. In

4:56

a sense, it's the most local of

4:58

these, I should say they're called F-Bolts by

5:00

the way. Okay, we talked about

5:02

that at the time, fast blue optical transients.

5:09

In fact, it's being hailed to

5:12

some extent in the literature as the sort

5:15

of prototype of its class, except

5:18

that it is a bit unusual. It's

5:22

an object that has a

5:24

lot of mystery attached to it. It's

5:29

clearly an explosion. The

5:31

transient itself is an explosion that was,

5:35

I think

5:37

it was this the one that was known as

5:39

the brightest of all time boat. I can't remember

5:41

whether this one was given that title, but it's

5:44

certainly up there with the boats. Basically,

5:49

the estimates are 10 to

5:51

100 times brighter than a

5:53

normal supernova. of

6:00

these objects that they're

6:04

characterized by something called a FRED.

6:07

I thought I'd just drag this in. Do you know what a FRED is?

6:10

I do not. It

6:13

stands for, it's in physics really, fast

6:15

rise exponential decay. Fast rise exponential decay

6:20

and it's any signal that

6:22

goes up very quickly and then you

6:24

know decays very slowly. And in a way that

6:27

covers all supernovae and

6:30

you know the objects in that sort of

6:32

class. I was just looking

6:34

online for a light curve for a

6:36

COW, I sent 2018 COW usually called

6:42

a cow. Let's see if I

6:44

can find one because that would,

6:47

yeah here it is. That's good. I've

6:50

got a volumetric light

6:52

curve and it is exactly that.

6:54

It's a FRED. It goes up

6:57

very quickly and basically

6:59

decays very slowly. Volumetric

7:03

is a measurement taken across all

7:05

wavelengths. I don't know whether you knew

7:07

that Andrew. It's measured

7:11

with a thing called a volometer

7:13

which looks, you know it's a

7:16

broadband detector. Most of

7:18

our detectors are limited to a

7:20

specific waveband but a volometer isn't.

7:22

It's usually used

7:24

actually in the microwave region of

7:27

the spectrum. But it also of

7:29

course because it's a fast blue

7:31

optical transient it's got optical

7:35

emission as well. But I'm just looking

7:37

now at the way

7:39

its spectra decayed. It's

7:44

basically what's

7:46

called a hot black body emission which

7:49

that's the shape of the spectrum. So

7:53

I think with F-box

7:57

generally and with this

7:59

object in particular, I

8:02

think really there's not that

8:04

much hard

8:06

and fast astrophysics that

8:08

means that

8:14

there is a common view

8:17

of what they are. I mean,

8:20

look, quoting, for example, from

8:22

our well-known source Wikipedia, the

8:24

precise definition of what constitutes

8:26

a fast-blue optical transient is

8:29

currently contentious in the literature,

8:31

largely defined by the observational properties rather

8:34

than the underlying mechanisms or objects. And

8:36

that's because we don't really know what

8:38

they are. So,

8:41

you know,

8:44

and the art,

8:46

that particular article goes on to make the point that

8:50

even when you lump them all together, when

8:53

you look at the details of the growing

8:56

number of these

8:58

events, there's

9:00

such big variations in their properties,

9:03

even though they're all classified as

9:05

fast-blue optical transients. They've got different

9:07

properties, different spectra, different

9:10

light curves, that's the up and down bit,

9:13

the amount of radiation it receives. So

9:16

it's saying, well, it

9:19

says it's potentially indicative of different progenitor

9:21

channels or explosion mechanisms. In other words,

9:23

all bets are off and I think

9:25

Terry's contribution is as good as anybody's.

9:28

Okay. So it might be on to something.

9:31

Yeah. Okay. Good

9:33

suggestion. Indeed. All right. Thank

9:36

you, Derek. Let's move on to a

9:38

question from Rennie, who is a regular

9:40

sender in-era. Rennie says,

9:42

what you're thinking about galaxies

9:44

like glass Z or glass

9:47

Z13 and how they

9:49

developed to such a mature state

9:51

in the early aftermath of the

9:53

Big Bang. Could it be they

9:55

worm-holed their way into our universe

9:57

from one that was separated by

9:59

a mere membrane we can't

10:01

understand when possibly the

10:03

fabric of that membrane was

10:05

disturbed by our universe's beginning.

10:09

That's come from Rennie. What

10:11

do you reckon? I suppose

10:14

the Lyman break galaxy

10:16

that means its spectrum tells

10:19

us that it's at a high

10:22

red shift because the ultraviolet features in

10:24

his spectrum are moved into

10:26

the infrared. I think the Z13 or Z13 I

10:28

guess refers to it. Wait

10:33

a minute, that's 12. I don't know whether that's

10:35

a numerical. I think 13

10:37

is red shift. The

10:40

red shift of course is a measurement of

10:42

how red shifted the spectrum

10:44

is. When you

10:46

get up to 13 you're looking back

10:48

to the very early phase of the

10:50

universe. Just

10:52

give me a minute. Yes, all right. Glass. I

10:55

did that. That's a very interesting thing

10:58

that I've come across before which is the Grissom

11:00

lens amplified survey from space. One

11:02

of the instruments using the James

11:04

Webb telescope. The Grissom by the

11:07

way, Andrew, I used to use

11:09

these when I was kind

11:11

of practicing astronomer, is a

11:13

combination of a grating and a prism which

11:15

is why it's called a Grissom. Both

11:18

of those have the effects of splitting

11:20

light into its rainbow spectrum colors and

11:24

the Grissom we're all familiar with. The Grissom

11:27

we're perhaps less familiar with but it consists

11:29

of a lot of lines

11:31

ruled on a substrate, usually a bit of glass,

11:34

which has the same effect of

11:36

dispersing light. The

11:38

phenomenon was discovered by a Scotsman by

11:43

the name of James Gregory in the

11:45

late 1600s. He held up

11:47

a – and he actually was the

11:49

professor of astronomy in the university that

11:51

I went to and I was there shortly after him

11:54

in the 17th century. He

11:56

Discovered it by holding a seagull feather up to

11:58

the sun and noticing that it split. Right

12:00

up into a rainbow of colors

12:02

that set aside on the technology

12:04

which is my strengths. Where is

12:07

Earth's the high redshift? Galaxies.

12:09

Ah, something that I

12:12

stand on the coattails

12:14

of my colleagues toast.

12:16

Or it's red shift

12:19

to hang on a

12:21

minute. I'm. It.

12:25

It's. Yes,

12:28

Suitcase. So that's why. The

12:32

some confusion here. It used to

12:34

be Cold Glass said thirteen. It's

12:36

now cold Glass said twelve

12:39

because it's redshift have been

12:41

as being read, a rear

12:43

reevaluated fryer Redshift of Twelve

12:46

still means it's one of

12:48

the earliest galaxies ever observed.

12:51

Days back to maybe three hundred

12:54

and fifty million years after the

12:56

Big Bang Nam. So we're talking

12:58

about a very, very early galaxy

13:01

now, having established oh that, would

13:03

you mind reading Reddit questions he

13:05

hadn't splinters all. Sat at

13:07

what issue time? What

13:10

is your thinking about? Galaxies like Glass

13:12

said. That. Anal Twelve and how

13:15

they developed a how they develop

13:17

develop to such. I'm into a

13:19

state in the early aftermath of

13:21

the Big Bang. Could it be

13:23

a wormhole their way into the

13:25

universe from one that was separated

13:27

by membrane? We can understand when

13:29

possibly the fabric of that membrane

13:31

was disturbed by. our universe is

13:33

beginning. To. Always asking if we

13:35

snatch this universe. Yeah no, I

13:37

were real hot as I get.

13:39

that's that's a. That's

13:41

a very nice idea. We.

13:44

We. Don't. is that this a

13:47

lot of study going on it's a

13:49

bit still it is kind of become

13:51

again a hot topic a have the

13:53

idea of wormholes we got no evidence

13:55

of the existence of where most by

13:57

the still mathematically allowed in this be

13:59

a lot recent

14:01

research and in the

14:03

fairly mainstream you know

14:06

that physics realm looking

14:09

at how and why

14:11

they might they might work and

14:13

whether we are missing

14:15

something by kind of

14:17

ignoring wormholes I

14:20

find that hard to believe that

14:23

it could happen I think what

14:26

we're seeing is the

14:29

evolution of properties

14:31

of galaxies exactly red is absolutely

14:34

right this this particular galaxy is

14:37

surprised everybody because it's only 250 million

14:39

years after the Big Bang and

14:41

everybody thinks that the things that we see

14:44

in the galaxy the

14:46

the elements that

14:48

you that it really should be

14:50

older than that in

14:52

other words you know have we

14:55

got the day to the Big Bang wrong now

14:57

that is unlikely

15:00

because our observations

15:03

of you know the physics

15:05

that tell us the date the Big Bang

15:07

are pretty rock-solid and

15:10

we've talked we talked about it already

15:12

last time when we talked about Arne

15:14

or the penjias the person who discovered

15:17

the cosmic microwave background radiation with his

15:19

colleague Bob Wilson that

15:22

discovery really set

15:24

the seal on our understanding

15:26

of the age of the

15:28

universe you've combined that with

15:31

the the Hubble flow that

15:33

the fact that galaxies are moving away

15:35

from us which is what really started

15:37

the idea that there was a Big Bang but you

15:40

combine those two together and you get measurements

15:42

which yes there's slight discrepancies there's

15:44

something called the cosmological

15:47

tension at the moment because there's

15:49

two slightly different values for what's

15:51

called the Hubble constant but

15:53

nevertheless the age of the universe is

15:55

pretty solidly back at about

15:57

13.8 billion years And.

16:01

A choice. I think the issue

16:03

here is no a cosmological one

16:05

is not that we've got the

16:07

a picture of the universe wrong

16:09

is that we've got galaxy evolution

16:11

rock that we we are not.

16:15

Really understanding fully

16:17

how you can

16:19

produce the. You.

16:21

Know that that the characteristics that we see

16:23

in another galaxy like that in such a

16:26

short time. Ah,

16:28

So it it's yeah, it's a

16:30

it's an interesting conundrum space. I

16:32

think it's one that is completely

16:34

reasonable. I don't find it one

16:36

that needs esoteric expeditions like things

16:38

popping out through where most of

16:40

the fabric of the the membrane

16:42

fabric of the universe and that's

16:44

what my base fab that's empty

16:46

rates as it says that the

16:48

universe might be or brain series

16:51

sometimes called be alright yeah the

16:53

that the universe might be just

16:55

city well as many membrane switch

16:57

each of which holds the universe.

16:59

Lovely theory you get a big

17:01

bang by the way when membranes

17:03

bank together and driven guess and

17:05

can imagine the at that. Might

17:08

well and I'm sure a lot

17:10

of people still speculate ever that

17:12

possibility, but it's probably something else

17:14

were missing and Galaxy development early

17:16

on. but does. Thank you ready?

17:18

let's go to Air and earlier

17:20

Question from Dave. Hey. Guys it's

17:22

safe from Calgary, Alberta the ah I'm

17:25

British but I live in Canada and

17:27

see accent and but I have a

17:29

question about the expansion of the universe

17:31

com or much and I'm going months

17:33

at a. Shorter. Wrong about

17:35

my theory, but I've never found an answer

17:37

to explain why I'm wrong. and am I

17:40

from? You guys can help out. So.

17:42

All the c The universe is expanding.

17:45

And. Is speeding up. My

17:47

question is is with it Why once

17:49

it ever slow down. And

17:52

I've heard about their dark energy is making

17:54

the speed up. Arm. But

17:56

my theory was similar to how

17:58

a gun. Around

18:01

our the gun speeds up.

18:03

Before. I guess to some point and

18:05

then starts slow down. Could.

18:08

That happen with the universe or was the

18:10

reason why about won't happen with the universe

18:13

I'm guessing as do of dark energy but

18:15

I'd love to know. Ah, Your

18:17

answer to it and probably explain it's

18:19

me personally. I very much. Thank

18:22

you Daves Couple from Canada

18:25

to date which is nice.

18:27

Arms outstretched as it's probably

18:29

a long. Bow. To

18:31

draw to compare the firing of

18:33

a bullet with the expansion of

18:35

the universe because the bullets affected

18:38

by the curvature of the earth

18:40

and gravity and atmospheric conditions. Oh,

18:43

add up to stop to the bullets

18:46

eventually. Ah, that doesn't exist in space,

18:48

doesn't. Know and

18:50

i'll def question is is a

18:52

good one and. I'd

18:55

say I'm gonna be encounters or in

18:57

about two months so it's nice to

18:59

have to. Tonight he questions ah the

19:02

and. So. That. I'm

19:05

in. this. The bottom line is

19:08

days right? Question this because we.

19:11

We. Can't guarantee what the universe

19:14

is gonna do business since

19:16

he's from the have any

19:18

said he sort of from.

19:20

Control. Over that or we could do

19:22

is observe what he's doing now and and

19:24

through the magic of the fact that we

19:26

use it that the we can look back

19:29

in time we get a good idea of

19:31

what he's done in the past. So am.

19:34

I. Think and other log. Compared.

19:39

This. Is another log of the kind

19:41

that Davis thinking of. Would.

19:43

Be better served for the expansion of

19:45

the universe. not by a bullet, the

19:47

by a rocket. Ah, because that this

19:50

is the thing that we think is

19:52

happening. and we talked about this couple

19:54

of weeks ago with the cosmological constant

19:56

and decreasing state and all that stuff

19:58

there. But

20:02

the idea of dark energy

20:05

is that space

20:07

itself has what might be called a vacuum

20:10

energy. It's just got an energy of its

20:12

own. And the energy

20:14

is in some way

20:16

proportional to the volume of the space.

20:20

That's what seems to be happening, even

20:22

though the numbers, as we heard a couple of

20:24

weeks ago, don't actually tie up exactly. But

20:27

it seems to be that as space gets

20:29

bigger, the energy

20:32

of space gets bigger

20:34

too. Because

20:37

this vacuum energy, this sort of repulsive

20:39

force that's pushing space apart, is

20:43

proportional to the space volume

20:45

itself. And

20:47

so what you've got is something that

20:49

is unlike a gun, which is propelled

20:51

down the barrel and

20:54

then doesn't have any propulsive force

20:56

keeping it going. And that's why it slows down

20:59

and it's air resistance, I guess, is

21:01

the main contributor to that. But

21:04

all the other things that you mentioned, Andrew, the curvature of

21:06

the earth and gravity, they

21:09

all play a part too. But

21:12

if you think of a rocket, what you've

21:14

got is basically

21:17

a motor that is actually

21:20

running for a long period.

21:24

And it's providing

21:26

that energy. But also

21:28

with a rocket, certainly one that's leaving the

21:30

surface of the earth, what you've got too

21:32

is that as the thrust

21:35

of the rocket, which is

21:38

constant, because it's determined by

21:40

the chemistry of what's going on

21:42

in the combustion chamber, the thrust

21:44

is constant. So the acceleration increases

21:46

because the mass is

21:49

going down. As The rocket goes

21:51

along, you're burning up fuel, so it's

21:53

lighter and so it gets more of

21:56

an acceleration. Some

22:01

that's really. From. I'm

22:03

better other logo thing for what's

22:05

going on with the. Accelerated

22:08

expansion of the universe. But.

22:11

As a said and I, we don't

22:13

know we we simply don't know what

22:16

the universe is gonna do. We thought

22:18

until the nineteen nineties that it was

22:20

definitely going to slow down because of

22:22

all the material in it, that that

22:25

would have a gravitational influence that would

22:27

tend to break the universe and that

22:29

is acceleration wrestler this so it's expansion

22:32

will be slowing down. but that is

22:34

not the case. In.

22:36

Mecca. so what's the suffice dive

22:38

because center it might sort itself

22:40

out a couple weeks. Sadly this

22:42

well if it does that's good

22:44

because we took about the office

22:46

but it's nut system the know

22:49

if either way the universe in

22:51

ten billion years' time is gonna

22:53

stop athiests with get off. Or

22:56

us take a dive at this space.

22:58

Nuts Andrew Dunkley here. Way of Professor

23:00

Fred? What's and. I

23:03

can. Let's take a short break from the shouted tell you about

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26:00

back to the show. OK

26:09

Fred, we'll go to another

26:11

question from the Netherlands. After

26:13

the Big Bang, the universe

26:15

started to cool. How

26:17

long after the Big Bang was the universe

26:19

at room temperature? And

26:22

how long was the universe at room temperature?

26:24

And can we set a telescope to zoom

26:27

in on that moment? Thanks for the answer,

26:29

kind of. Jost from

26:31

the Netherlands. Does

26:34

it mean actual room temperature

26:36

or the universe's interpretation

26:39

of room temperature? No, I think it

26:41

means room temperature. Let

26:43

me just see if I

26:45

can answer this precisely. I

26:48

can give a hand waving answer. And

26:53

certainly we can't tune the telescope to look back

26:55

on it and I'll tell you why in a

26:57

minute. But let me just see if I can

27:00

bring up a cooling curve for the universe that

27:02

would actually give us a

27:05

time when the

27:08

temperature was room temperature. Here

27:11

we go. I've got loads and loads

27:13

of cooling curves. Yeah,

27:16

there's an older one. So

27:20

yes, it may well

27:22

be that

27:25

it's longer than I thought that the

27:27

universe is actually

27:29

older. I was going to say

27:32

it was probably within the first few minutes. And

27:35

of course you can't

27:40

see to within the first few minutes of the universe

27:42

because we can't see anything when

27:44

the universe was less than 380,000 years old. That's

27:48

the age of the universe

27:51

at the level of the cosmic microwave background

27:53

radiation beyond which we can't see. So

27:56

we've got this veil that's drawn over a universe

27:58

younger than 300,000 years old. hundred eighty thousand

28:00

years. It is

28:04

in the region of a million years by

28:07

the looks of it, million years. It's

28:10

before the formation of galaxies

28:13

and it's still in a, you're not quite

28:19

still in a radiation dominated universe

28:22

but you are close to that.

28:26

So I think it's

28:30

longer than I thought it was and

28:32

it looks as though it's of order

28:34

of the same length of time as

28:38

the time it took for the universe to

28:41

become transparent because that's the

28:44

time that we're looking back

28:46

to in the cosmic microwave background

28:48

radiation. You're looking completely baffled Andrew.

28:51

I'm rambling here because I

28:54

found a conflicting article that

28:56

says that during a very

28:58

brief window between 10 to

29:01

17 million years after the

29:03

Big Bang the temperature of

29:06

the cosmic microwave background was about

29:08

80 degrees Fahrenheit close to room

29:11

temperature. Okay. That is from Arby

29:13

Loeb. Oh yeah well yeah

29:16

he's a name to reckon with. He's a

29:18

very controversial figure. Just

29:20

tell me what the number

29:22

was. No tell me what the number

29:25

was there that you said. Read that bit again. During

29:28

a very brief time window between

29:30

10 to 17 million years after

29:32

the Big Bang the temperature of

29:35

the CMB was around 80 degrees

29:37

Fahrenheit. 10 to 17 million years.

29:40

That's not a brief interval that's seven

29:43

million years. It is it is and

29:46

I did find another article that

29:48

said six million so yes yeah.

29:53

So I'm saying in the region of a million

29:55

he's saying in the region of 10 million in

29:57

cosmology that's the same thing. That's

30:01

interesting. It's a really interesting question

30:03

though. I didn't get

30:05

the questioner's name, Andrew. That

30:08

was Jost. That's from the

30:10

Netherlands. Yeah.

30:14

It's a really interesting question. But

30:16

it's in the homework folder, if you like. Yeah, we should try and tie it

30:18

down a bit more. But Avi's probably

30:20

right. He is, I think he's

30:24

still the director of the Harvard-Smithson IFA,

30:27

the Institute for Astronomy, one

30:29

of the most renowned astronomical

30:31

entities in the universe, sorry,

30:33

in the world,

30:35

possibly the universe as well. But

30:39

always looking for evidence

30:42

of extraterrestrial intelligence. He's

30:44

the gentleman who thinks Oumuamua was

30:47

a bit of a spacecraft that

30:49

flew through the solar system. Yes.

30:52

Indeed. All right. Well, we'll follow

30:54

that one up for you, Jost. But there

30:56

are some people who speculate

30:58

or believe it was probably 10 to 15,

31:01

10 to 17 million years after the Big

31:04

Bang and lasted quite a long time. Thanks

31:07

for your question. Let's go to Brian. Oh,

31:09

look, it's a black hole question. This

31:12

is Brian Plowski from

31:15

Columbus, Georgia. My

31:18

stepson and I were talking about black holes

31:20

and he asked me a question. He's 10

31:22

years old, by the way. Can

31:25

a black hole be destroyed?

31:28

What do you all think?

31:31

By the way, we love your podcast. We listen to it

31:33

on the way to school every morning. Very

31:35

cool. Thank you, Brian. Can

31:38

a black hole be destroyed? Yeah,

31:42

I don't know. That's a good question. I

31:46

would suspect yes, but it'd

31:48

have to be very extreme

31:50

circumstances. So, yes.

31:53

So the standard answer to

31:55

this is yes, but on the

31:57

very own, I think extreme

32:01

circumstances. So

32:04

we know from Stephen Hawking's work

32:06

in the 1970s that's been verified

32:10

by analogues rather than by observation.

32:13

But we know that black holes can evaporate

32:15

by they

32:18

release what's called Hawking radiation which

32:21

is electromagnetic radiation. It's

32:24

very, very weak radiation however

32:27

and takes a very long time for

32:29

the black hole to

32:31

evaporate altogether. In

32:34

fact longer than the current age of

32:36

the universe for pretty well all black

32:38

holes. There may have been some tiny,

32:40

tiny, tiny ones that evaporated

32:42

early on in the universe but

32:44

the evaporation time

32:47

is just, the evaporation rate is so

32:49

slow that the time is very long.

32:51

So that's the answer

32:53

is yes they can be

32:56

destroyed because they don't last forever. They

32:58

last nearly forever. Numbers

33:01

like 60 billion years are the ones that

33:03

I've come across. I think I wrote about

33:06

that in one of the books about how

33:08

many, how long it would take an

33:10

earth-sized black hole to evaporate and

33:12

it's a huge, huge number. But

33:16

whether you know

33:18

conditions in the early universe when

33:22

things were so extreme whether if

33:27

you could throw a black hole into that

33:29

early universe it would survive. That's

33:32

a different question. I

33:34

suspect, I mean, you

33:37

know, some

33:40

of the thinking is that those extreme

33:42

conditions in the early universe

33:44

came from a black hole anyway. Roger

33:46

Penrose's idea that you

33:48

know this formation of black holes in

33:50

space, giant black holes are

33:53

big bangs and so that

33:56

tends to shed a bit of light on that. But

33:59

I think... for

34:03

Brian and his grandson, I

34:06

think the answer is

34:08

yes they can but it's a slow

34:10

process. Okay,

34:12

there you go. Let's go to

34:15

our next question. Thanks Brian. In

34:18

regards to your grandson or nephew, I can't

34:20

remember. Sorry, I

34:22

probably got it wrong. That's

34:25

perfectly okay. Your relatives made, we

34:27

just made Brian a lot older than he probably is. Sorry,

34:31

bro. Sorry, bro. But

34:34

you know, when you're talking about the age of the universe,

34:36

it's not much of a difference. Yeah. Mark

34:38

has sent us a question. With regard

34:41

to the recent mention of the ghost

34:43

galaxy such as Aztec 71, if

34:47

it turns out that there are

34:49

many far infrared visible galaxies in

34:51

the universe, would the presence of

34:53

all their normal matter significantly

34:56

reduce the need for the

34:58

existence of so much dark

35:00

matter? Thanks for the

35:02

wonderful podcast. Mark, he's from Bloomington,

35:04

Indiana. Ghost

35:07

galaxies and infrared galaxies' presence

35:09

of normal matter significantly reduce

35:11

the need for the existence

35:13

of dark matter, so much

35:15

dark matter. Yes,

35:17

that's right. I think, just remembering

35:20

our chat about that, that

35:23

it's a galaxy

35:25

that in normal telescopes

35:27

is invisible because

35:30

it's such a dusty

35:33

galaxy. And

35:37

they, I guess

35:39

the idea is that this has

35:41

been, was it observed by

35:44

the, yes, observed by the James Royk telescope.

35:46

That's right. That's the story that we did back

35:49

in December. So I think

35:53

the physics of this particular

35:55

galaxy, Aztec 71, are fairly

35:57

clear-cut in that it is

36:00

real matter that is obscuring it.

36:02

It's dust. It's the normal smoke-like

36:05

material that we know permeates. Galaxy is

36:07

our galaxy. In our galaxy you could

36:10

see it. Certainly the dust lanes in

36:12

the Milky Way, those dark clouds in

36:14

the Milky Way are just the same

36:16

sort of dust that we're talking about

36:18

here. But

36:21

it's normal matter

36:23

that is contributing

36:25

to its invisibility.

36:28

So there is

36:30

certainly an interaction though with

36:33

dark matter because galaxies tend

36:35

to be rich in dark matter.

36:39

And I suspect

36:44

that any dark matter

36:46

confusion that there is because of the

36:48

fact that we can only see this

36:50

galaxy in the infrared, I

36:53

suspect that is, I

36:57

think it's a

37:00

minor detail compared with our general

37:02

understanding of dark matter, which actually

37:04

comes not just from looking at

37:06

individual galaxies but from the structure

37:08

of the universe. So we can

37:10

actually probe the

37:13

geometry of the universe which leads us to

37:15

information that's about the amount of dark matter

37:17

that there is in the universe. And that's

37:20

consistent with what we see in individual galaxies.

37:22

So I don't think there's an

37:24

issue there. But it's a nice thought.

37:26

Yeah, yeah. Good on

37:28

you Mark. Thank you so much. This is

37:31

Space Nuts. Andrew Duncley here with Professor Fred

37:33

Watson. Space Nuts. Space

37:35

Nuts. Okay

37:41

Fred, we've just got a few more

37:43

questions to go before we wrap this

37:45

one up. And we didn't get the

37:47

name of this listener because it cracked

37:50

up at the beginning. So apologies but

37:52

we got the general gist. Let's hear

37:54

from Perth again. I was

37:56

listening to your episode on the

37:58

oldest black holes. these supermassive black

38:01

holes that occurred for

38:03

the very early start of the universe. And

38:06

I was just thinking that if gravitons existed,

38:09

could they have been an elementary particle formed

38:11

in the black hole and the big bang

38:13

and could they have clumped together to form

38:16

the first black holes? Thank

38:18

you, bye. Thanks

38:20

for the question. So did

38:23

you get the gap? Yeah, I did. Yeah,

38:25

good. I was

38:27

trying to remember what he said. Yeah,

38:31

so if gravitons existed,

38:33

could they clump

38:35

together to form black holes?

38:37

And I think the answer is

38:41

no, because

38:44

gravitons, if they exist, would be

38:46

bosons, which are force

38:49

carriers and

38:51

not, is it

38:53

leptons, the other kind that make up matter?

38:56

And you need matter to make black holes. So

39:00

I think that is the answer.

39:02

Actually, I should check that. I'm

39:04

not talking rubbish to help. Gravitons

39:10

are theoretical, I think. Yes, they are.

39:13

Yeah. But

39:17

leptons is the wrong word for what

39:19

I'm trying to say. But

39:22

basically, bosons are force carriers and

39:25

the other kind aren't. And

39:27

you need the other kind to form black

39:29

holes. I'm

39:32

sorry, throw in the leptons, which

39:34

are actually a different category

39:36

of elementary particles.

39:39

But you get the idea that they're

39:42

the wrong kind of leaves, if I can put it that

39:45

way. Yeah, OK. British Railways used to

39:47

say when their trains were late, oh, wrong kind of

39:49

leaves, leaves on the tracks. So

39:54

gravitons, I don't think, could clump together to

39:56

make a black hole. I'm

39:58

not a particle physicist. but

40:01

that's the way it would look to me. Fair

40:04

enough. Alright thanks for the question. Yeah

40:08

we're getting a lot of pretty heavy-duty

40:10

ones today. This one comes

40:12

from Garrett in

40:15

I love where Garrett lives,

40:17

Dripping Springs in Texas.

40:19

Yeah that sounds like a fun

40:21

place. Yeah I'm going

40:23

there. I'm actually going there.

40:25

Yeah. Next month.

40:28

Yeah. Oh the month after next because

40:30

that's near where the eclipse pass is. So

40:33

we're going to be in Dripping Springs passing through. Very

40:36

beautiful. Yeah I'm sure it is. He

40:40

says during the differentiation phase

40:42

as proto-earth accreted out of

40:44

the collapsing disk of dust

40:46

while a lava glob form

40:48

the elemental species

40:50

were able to rise and fall

40:53

to an equilibrium depth within the

40:55

gluck ball. This is all official.

40:58

Love that beach here. Each according

41:00

to its atomic weight. With the

41:03

heaviest isotopes also being the least

41:05

stable I might have expected everything

41:08

bistial like U-235 to sink

41:11

to the center of the core with

41:13

the weight of the entire mass of

41:15

the planet pressing on all sides till

41:17

boom clearly this

41:19

did not happen.

41:22

Why? How do you

41:24

know it didn't happen? Look

41:30

sorry I didn't get the name

41:32

there was that. Garrett. Garrett. That's

41:34

right. Yeah sorry. So there certainly

41:36

is a nuclear efficient

41:42

taking place underneath the

41:44

surface of the earth as

41:46

we speak there are natural nuclear

41:48

reactors which are basically

41:50

what what Gary's talking about

41:54

there in the probably in

41:56

the crust actually rather than the mantle so they're

41:58

quite near the top. And that might come

42:00

from later bombardment

42:03

of the Earth by

42:05

up-proser planets or planet

42:07

isimals that deliver those

42:09

high-density materials to

42:11

the surface of what was by then

42:14

the differentiated Earth. So

42:17

reactions do take place and they

42:20

are constantly doing that. But I

42:22

think the difference is we

42:25

don't get the explosive chain reaction that

42:27

Garrett's thinking of, something that blows up.

42:29

And maybe there just isn't enough of

42:32

the material to do

42:34

that or the energies are not high

42:36

enough. I don't know the answer to the

42:39

question. It's a good one. But

42:43

nuclear fission does take place within the Earth.

42:46

We actually think that the

42:49

core is reasonably active in this

42:51

regard and it's one reason why it's

42:54

still warm. So it's

42:56

more like, perhaps, should I say, it's

42:58

more like a nuclear reactor in a

43:01

power station than a nuclear

43:03

reactor in a fission

43:05

bomb, a atomic bomb. So

43:10

that's the short answer.

43:14

And knowing what the mix of these

43:16

fissile materials is that would actually give

43:19

rise to such a situation is the

43:21

subtlety that I'm not across. But

43:24

it's a great question. And

43:26

clearly, as far

43:29

as we know, there wasn't a boom. But

43:33

yes, the question's with

43:36

Murray because fission is taking place.

43:38

And it is one reason why we think

43:42

things like orphan planets are visible.

43:45

And these are planets that seem to

43:47

exist without any star. We

43:49

can see them in the infrared region of the spectrum

43:51

because they're warm. That warmth is thought

43:53

to come from within the

43:55

fission processes, nuclear reactions deep

43:58

within the atmosphere. cause

44:00

which is not nuclear fusion which will turn

44:02

into a star but nuclear fission which makes

44:04

it warm interesting

44:08

um i i

44:10

don't i don't know how i'm drawing this

44:12

connection but uh garrett wasn't there an early

44:14

steam engine named garrett uh

44:17

it's not early it's uh

44:19

was developed in the 20s

44:23

i think it's a an articulated steam locomotive

44:25

oh that's the one yeah garrett locomotives and

44:28

they were used here in australia they were

44:30

used they trialled them between sydney and dubbo

44:33

well there you go did they yeah that's why

44:35

i remember it came up in our archival news

44:37

segment that i do on the radio every day

44:40

yeah the garrett steam engine yeah there

44:42

you go to garrett big locomotives big

44:44

yeah no yeah that was

44:46

certainly big and powerful um

44:49

thanks garrett our final question comes from

44:52

guess who hello

44:54

spacemat martin

44:56

vermin gorvine here writer

44:59

extraordinaire in many

45:01

genres and

45:03

today's question is how

45:06

many habitable planets

45:09

could you get in

45:11

in a single

45:13

solar system like what might

45:15

the maximum be and

45:18

bonus follow-up question could

45:20

you have more than

45:22

one habitable planet orbiting

45:25

not the parent star but

45:29

a gas giant so you could have

45:31

could you get like two or more

45:33

means of the gas giant

45:37

of a gas giant orbiting

45:40

the parent star and

45:44

one thing that i can set your minds

45:47

at ease about i will never be

45:49

asking for advice on telescopes

45:53

uh because i brought up the subject

45:55

with my wife and she told me

45:58

about a friend or anything her

46:00

is his marriage started downhill

46:02

and ended in divorce when

46:05

her husband started buying all these

46:07

amateur calisthenics. Can't

46:10

wait for your answer on the habitable

46:12

planet thing. Fervin,

46:14

Gloravine, over and out,

46:18

out, out. Martin,

46:20

thank you so much. Always good

46:23

to hear from him. Very entertaining as usual. Alright,

46:26

so how many habitable planets

46:29

and could you have more than one

46:31

orbiting a star or

46:33

a gas giant? Look,

46:36

you could throw any number up and you might be right or wrong.

46:40

Yeah, there's physics

46:43

which would determine

46:45

how many habitable

46:47

planets you might have in

46:53

the habitable zone of a

46:55

star. Intuitively,

46:58

I'm thinking that

47:01

it certainly could be

47:03

more than one. We think,

47:07

well, that's not as daft as it

47:10

sounds because if you put

47:12

a planet in the…

47:16

so the habitable zone around the star

47:18

is not very wide, that's the thing.

47:20

You get too close and it's too

47:23

far away and it's too cold and

47:26

the Earth sits right in the Sun's

47:28

habitable zone. And it really upsets bears.

47:32

Well, it would, that's right, especially if there's coming

47:35

threes. So that's why you

47:37

need the Goldilocks zone. So the

47:41

orbital dynamics of

47:46

an object being joined

47:48

by another object within the same

47:50

zone of a star's

47:55

habitable zone might

47:57

mean that one just gets kicked out straight

47:59

away. way because they

48:01

interact gravitationally. When

48:04

you think about it, we do know that there

48:07

are ways that objects can share orbits

48:10

and most

48:12

notably when you think

48:14

of a planet like, let's say Jupiter, even

48:16

though Jupiter is not in the habitable zone,

48:19

that's accompanied by two swarms of asteroids,

48:21

60 degrees ahead of it

48:23

and 60 degrees behind it in its orbit

48:26

called the Trojan asteroids. They basically

48:28

are centered on the Lagrange points, the two

48:31

L4 and L5

48:33

Lagrange points. That

48:38

means that you can have more

48:41

than one object sharing the same orbit

48:44

as long as they're in particular geometrical

48:47

relationships. I

48:51

think the answer is yes, you could. I don't know what

48:53

the maximum number is, but

48:55

I think you could have more

48:57

than one object that might be

49:00

not quite planetary in size but big

49:03

enough to be within the habitable zone

49:05

if you could set up a base

49:07

there or something like that. I

49:12

imagine that most stars,

49:15

except maybe the supervolatile ones, would

49:17

have some kind of golden lock

49:19

zone. Within each, there could

49:22

be habitable planets. You're

49:24

talking squealings. Yes, that's right. In

49:28

terms of the habitable zone, that's right. There

49:31

was another aspect of Martin's

49:33

question which I didn't quite get because he

49:35

talked about moons going around red giants and

49:39

moons go around planets, not stars. I

49:41

wasn't quite sure what he was getting

49:44

out there. Did you? No,

49:46

I didn't catch it, but maybe

49:48

he means moons that are orbiting

49:50

planets going around red giants.

49:53

I mean, could you have a habitable

49:55

planet and a habitable moon? Would be

49:57

the same, perhaps. be

50:00

by the same. I suppose any combination is possible

50:02

isn't it? Well

50:04

that's one thing that we're learning as we

50:06

discover more and more exoplanets. You know we

50:09

think the solar system was the typical

50:13

system of planets. If other planets existed then

50:15

we started discovering other planets and none of

50:17

them looked like the solar system. It's

50:22

very well ordered compared with many

50:24

of the ones that we're observing. Part of that

50:26

might be a selection effect though Andrew because it's

50:29

easy to discover big planets and not

50:31

so easy to discover small planets. Yes,

50:34

which are usually the habitable

50:36

ones or potentially habitable ones.

50:38

I suppose you also have

50:40

to draw a line under

50:42

what is defined as habitable.

50:46

Habitable for humans, alright, well that reduces

50:48

the odds significantly but habitable for something

50:51

that's alive could

50:53

be many. Then you've got to define what

50:55

alive is. Well that's

50:58

right, going. Another definition of life, yes we

51:00

don't have a definition of life. Good

51:03

luck with your telescope Martin, thank you so

51:05

much for sending in

51:07

your questions. It's an

51:09

interesting one is that and I think he's right, it can

51:12

lead to all kinds of... Because astronomy

51:15

and certainly when it comes to buying

51:17

telescopes it's totally addictive and you get

51:19

what's called aperture fever. You've got to

51:22

have a bigger one to

51:24

show a bit more. Yes,

51:26

absolutely. Thanks Martin, thanks to

51:28

everyone who sent in questions, really appreciate

51:30

it. Please keep them coming. You

51:33

can do that via our website,

51:35

spacenutspodcast.com, spacenuts.io and click on the

51:37

AMA tab to send us a

51:39

text or audio question or click

51:41

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51:44

on the right hand side of the home page and

51:46

have a look around while you're there. Maybe

51:49

if you're one of the social

51:51

media followers, subscribe

51:53

on YouTube or any of our

51:55

other platforms, the more subscribers the

51:58

better. That

52:00

wraps it up for another show Fred, thank you so

52:02

much. It's a pleasure Andrew

52:04

and I look forward to more settled

52:06

stories in the next few

52:09

weeks. I

52:12

don't know about you but I love the potlucks. Yeah,

52:14

I approach to it. Yeah, I know

52:17

you don't. It's not that

52:19

I don't. It embarrasses

52:21

me because it reveals my levels

52:23

of ignorance about certain topics. Oh

52:26

gosh, no I don't think so. I think

52:29

it's, you know, people are throwing

52:31

curve balls all the time and can't hit them all.

52:33

No. I was like, everyone wants to

52:35

hit them all. See you.

52:38

Alright, thank you Fred. See you soon.

52:41

Cheers. Bye bye. I'm

52:43

Fred Watson, astronomer at Large and thanks to

52:45

Hugh in the studio. Let me just check

52:47

and see. Nobody

52:50

home. Alright. And from me, Andrew

52:52

Duncley, thanks for joining us. I hope you can catch us on the

52:54

very next episode of Space Nuts. Bye

52:56

bye. Space Nuts, you'll

52:58

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53:01

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53:03

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