0:00

Is dark matter close to us or

0:02

far away? How dangerous

0:04

were those recent solar storms? And

0:07

is there any way we can make the Drake

0:09

equation better? All this and more in this week's

0:12

question show. Welcome to the question

0:14

show. Your questions, my answers. As always, wherever you

0:16

are across my channel, the question pops in your

0:18

brain. Just write it down. I'll gather them up

0:20

and I will answer them here. All right, let's

0:22

get into the questions. Ryan,

0:25

is dark matter observed only at the

0:27

farthest reaches of the universe or is

0:29

there dark matter closer? So

0:32

dark matter is observed at all

0:34

scales in the universe. It's

0:37

seen both relatively close by

0:39

like when you measure the

0:41

movements of the stars within the Milky

0:44

Way. And it's also measured at the

0:46

farthest scales that we can possibly perceive,

0:48

which is in the cosmic microwave background

0:50

radiation and everywhere in between. So we

0:53

see the effect of dark

0:55

matter through the movements of galaxy

0:58

clusters colliding with one another.

1:01

So I'm going to run through the various lines

1:03

of evidence that tell us that dark matter is a

1:05

thing and sort of give you a

1:07

sense of the scales for where we're seeing these, these

1:10

lines of evidence. So the

1:12

one that's kind of the closest is

1:14

the movements of the stars in the Milky

1:17

Way. And so when you envision all of

1:19

the stars going around the center of

1:21

the Milky Way, compare

1:23

that to the planets that are going

1:25

around the sun in the solar system.

1:28

So you've got these planets, for example,

1:30

Mercury is going the fastest going over

1:32

40 kilometers per second. And

1:35

then Earth is going 30 kilometers

1:37

per second around the sun and Neptune is

1:39

going like five kilometers per second around the

1:41

sun. You've got this drop off, it's very

1:44

linear drop off as you get farther and

1:46

farther away from the sun. And

1:48

this is what you would expect if you

1:50

have a bunch of objects that are orbiting

1:52

around some gravitational center. So the sun with

1:55

the planets going around it, that's the way

1:57

you sort of see the change in the

1:59

velocity. of the planets that are orbiting around

2:01

it. Now, if you do that same measurement of

2:04

the stars going around in the Milky Way, the

2:07

stars that are very close to the center of the Milky

2:09

Way, the ones that are quite close to the supermassive black

2:11

hole, are moving very quickly. And

2:14

then the speeds slows

2:16

down as you get farther away from

2:18

the center of the Milky Way by

2:20

a little wave. And then something super

2:23

weird happens, which is that

2:25

the speed doesn't change. So even though

2:27

you're going farther and farther away from

2:29

the center of the Milky Way, the

2:31

speed remains exactly the same, or roughly

2:33

the same, around 250 kilometers

2:36

per second. And they

2:38

don't drop off in the way that you

2:40

expect. And so how is that even possible?

2:42

The only way that you can have that

2:44

be possible is that it's not that all

2:46

the stars are orbiting around some center

2:49

of gravity the way it is in the solar system.

2:51

It's if the stars are

2:54

embedded in some much larger

2:56

thing that is just turning,

2:58

and the stars are turning inside of

3:00

that thing. And so when

3:02

you run the math to say, how much

3:05

stuff would it take to get the behavior

3:07

of the stars as we see them here

3:09

in the Milky Way, and in every other

3:11

galaxy, you need about 10 times as

3:13

much mass in the Milky Way as what we can

3:16

perceive. When you count up all stars, you get 10

3:18

times as much mass. So that

3:20

is affecting the sun. Now

3:22

we don't know if dark matter, if

3:24

it is like a particle, that

3:26

there's dark matter particles in you right now

3:29

today. There's dark matter particles that are moving

3:31

around in the solar system. It could be

3:33

dark matter particles. Or maybe there's just, there's

3:35

primordial block holes that are a thousand times

3:37

the mass of the sun. And they're tens

3:40

of light years apart, but they add

3:42

up on average to making the Milky

3:45

Way move that way. And so that's

3:47

very close. And then when

3:49

you look a little further out, actually

3:51

the other one is that the speed

3:53

of rotation of galaxies is too fast.

3:55

So they should be tearing and shearing

3:57

themselves apart. But for some reason... the

4:00

galaxies are able to keep themselves together

4:02

as if there was more matter gluing

4:05

them together than what we can

4:07

perceive. And then when you look farther

4:09

away, we can see gravitational

4:11

lensing. So when astronomers

4:13

map the universe very

4:16

carefully, they're able

4:18

to see these distortions of light where

4:20

light has made this journey from a

4:22

distant galaxy to our telescope,

4:25

but it's been curved and bent

4:27

and warped. And you can actually

4:29

imagine you're looking through water, like

4:33

water that's rippling at, say,

4:36

trees or something. You're lying on the bottom of a

4:38

pool, you're looking up, there's trees above you, and you're

4:40

seeing the trees are getting all kind of warped. And

4:42

so you know that there is water in

4:45

between you and those trees because you

4:47

can actually measure. And you could measure

4:49

the depth of the water if you

4:51

sort of knew the true shape of those

4:53

trees and you were able to measure the

4:56

warps and the changes. And so when astronomers

4:58

measure just very carefully the structures

5:00

of the universe, it all looks like it's

5:02

in a bit of a funhouse mirror,

5:04

warped and wobbled. And then you

5:06

can calculate the amount of gravity that would take

5:09

to distort the path of the light as it's

5:11

moving from more distant objects to be able to

5:13

tell you and match

5:15

what you're seeing. Once again, you need

5:17

about 10 times as much mass to

5:19

account for those kinds of changes of

5:22

the light's path to be able to get

5:24

to. And then you've

5:26

got things like the bullet cluster

5:28

where you've got giant galaxy clusters

5:30

that are colliding together. And what

5:33

you get is the mass that

5:35

is the distorting mass seems

5:37

to pass directly through us. You galaxies

5:39

are colliding with one another, the stars

5:41

pass right through each other, the

5:44

extra distorting mass also passes right through, but

5:47

the gas and the dust kind of collides

5:49

in the middle and piles up and heats

5:51

up. And so we know that

5:53

whatever this thing is, it seems

5:55

to hang out with the stars and

5:58

can be separated. From other

6:00

things and then we can actually see examples

6:03

of dark matter where we can see galaxies

6:05

when you sort of look for the Warps

6:07

and the wobbles around a

6:09

galaxy. You don't see it So

6:11

there are galaxies that have a lot of

6:14

stars But they don't seem to have

6:16

any dark matter in them and then you

6:18

look at other galaxies where you can see

6:20

this distortion of space But

6:22

there are almost no stars inside of it.

6:24

And so it's like it's a galaxy that's

6:27

made almost entirely of dark matter and and

6:29

then at the far the systems of the universe we

6:32

see the cosmic microwave background radiation and essentially

6:34

the Anisoptera visa

6:36

the changes in temperature that we

6:39

measure in the cosmic microwave background

6:41

radiation could only exist if The

6:44

you had an amount of dark matter in the

6:47

universe that matches all of the other observations. So

6:50

There are so many observations for dark matter

6:53

Nobody knows what it is, but that's fine.

6:56

Right? Like this is how it starts you you See

6:58

a bunch of stuff and say that's weird and

7:00

then you measure it. So Back

7:03

to your question dark matter affects us

7:05

at our galactic level at the Milky Way's level.

7:07

So it's whatever it is It's around us and

7:11

also seems to have an influence across the

7:13

entire universe in every direction as far as

7:15

we can see. I Hope

7:17

you noticed the Star Trek planet name that appeared

7:19

above my shoulder This is a way for you

7:21

to vote for you to tell us what you

7:23

thought was the best question best answer Combo

7:26

whatever whatever you thought was best So

7:31

the winner this week was for dr.

7:33

Whale a refi and Asking

7:35

what would happen to a spaceship that was

7:37

going at 50% the speed of light and

7:40

hit a piece of sand So thank you

7:42

everybody who voted and chose that as their

7:44

favorite question answer now we will

7:46

put a different Star Trek planet name above my

7:48

shoulder for each of the Questions and we'll put

7:50

them in the show notes and we'll put a

7:52

list down below and so just go ahead and

7:55

put the name Of the question down in the

7:57

comments down below and that's a way to vote

7:59

and we'll them up next week and we

8:01

will celebrate again. Vincenzo R.

8:03

How accurate do you feel MOND is to

8:05

explain the gravity problem the standard model seems

8:07

to have? I'm a bit fuzzy on what

8:09

MOND really says. So

8:11

MOND is modified Newtonian dynamics.

8:14

It is another explanation for

8:16

dark matter. And the gist

8:18

of MOND is like all

8:20

those observations that I mentioned

8:22

before, that those all

8:24

assume that gravity works the way

8:26

we understand it at the local

8:28

level, kind of like Newtonian, and

8:31

includes all of the relativistic

8:33

stuff introduced by Einstein, that

8:35

we understand how gravity works

8:37

at various scales in the

8:39

universe. But what MOND says is

8:41

that maybe we don't completely understand

8:44

how gravity works at the largest

8:46

scales, that when you want to

8:48

look at scales that are even

8:51

greater than say

8:53

that which is affecting

8:55

stars interacting with one

8:57

another, then you can

8:59

put in a fairly

9:01

straightforward additional factor into

9:03

your gravitational calculations. And

9:06

suddenly, it

9:09

answers many of the same questions

9:11

that the particle idea for dark

9:13

matter does. That if

9:16

gravity worked a little differently than we understand,

9:18

then you would see stars moving in galaxies

9:20

in the way that we see them, that

9:22

you would see galaxies not tearing

9:24

themselves apart as they rotated, you would

9:26

see all of these various observations. But

9:32

there are some problems, like there's

9:34

a lot of other observations, like

9:36

say that gravitational lensing that I

9:39

mentioned, it's really hard

9:41

to say, well, why would

9:43

one galaxy have a lot

9:47

of this extra factor for gravity, but

9:49

this other galaxy has almost none. What

9:51

is the difference between those two galaxies?

9:53

If we know the total mass of

9:55

the stars in those galaxies, then we

9:57

should know how to do that. how

10:00

much of a gravitational interaction they

10:02

should have. Now,

10:04

there are a lot of people that still

10:06

think that that mind is the

10:09

answer, but they're having a harder and harder

10:11

time these days being able to convince the

10:13

rest of the astronomy community. And so, you

10:16

know, this is how science works, that

10:19

an observation is made, someone says, huh,

10:21

that's funny. And then people

10:23

try to explain it. And they come

10:26

up with theories, and then they make

10:28

observations and find out whether or not

10:30

those observations match back against the original

10:32

theory and provide more evidence one way

10:35

or the other. And it's been this

10:37

long process over decades and decades, where

10:39

the evidence is growing that dark matter

10:41

is some kind of particle. And

10:44

the evidence is declining that dark matter

10:46

is just that we don't

10:49

understand gravity at the largest scales. But

10:51

mind has not been completely disproved. And

10:54

so people come back around almost

10:56

every week with a new

10:58

paper that incorporates mon and comes up some new

11:00

ways to account for some of its issues.

11:04

People address them in the you know, in

11:06

the scientific literature and the conversation goes back

11:08

and forth. I mean, the other one that

11:10

you can't rule out is primordial black holes,

11:12

that there are black holes left over from

11:14

the beginning of the universe and they are

11:16

dark matter. There is no particle. There are

11:18

just black holes. Does that make you

11:20

feel better? Damon Gates thoughts on

11:23

the lack of impact from the G5 sunspot

11:25

emissions that hit Earth. So

11:27

when I'm recording this, we are at

11:29

the tail end of a series of

11:31

very powerful solar storms that struck the

11:33

Earth. I think over the course of

11:35

a couple of days, we got eight

11:38

X class flares, maybe six X

11:40

class flares, and the X class are

11:43

the most powerful types of flares that

11:45

the sun gives us. And

11:47

when an X flare is directed towards

11:49

the Earth, and you get a coronal

11:52

mass ejection, you get particles coming from

11:54

the sun interacting with the Earth's magnetic

11:56

field, you get auroras seen

11:59

in regions. that maybe you wouldn't

12:01

normally be able to see them. And you

12:03

also get disruptions in our communication, electrical

12:05

problems, satellites can go down. So it can

12:07

be both wonderful because you go out

12:09

in Florida and see the auroras. But

12:11

it can also be a little scary because

12:14

you know, some of your electronics can

12:16

have problems. And we know that there are

12:19

much, much worse versions of solar

12:22

flares that have hit us in the past.

12:24

The most famous of these is the Carrington

12:26

event, which hit earth in the 1860s. And

12:29

was so powerful that people saw auroras around

12:31

the entire planet, telling us poles were lit

12:33

on fire. And this was a largely

12:36

non-technological society at that point.

12:38

And yet, already, just

12:40

the faint bits of technology that

12:42

people have, we're starting to fail.

12:45

Now, from what

12:47

I understand, the Carrington events was

12:49

an X-45, which

12:54

is an extremely powerful solar flare. And the

12:56

most powerful of the recent group, grouping

12:59

that we had was X8.6.

13:04

And I believe that sort of the process goes up by

13:06

orders of magnitude. So, so an

13:08

X-45 is a dramatically more powerful flare than

13:10

an X8.6. And so you're just not going

13:13

to get the same kind of damage.

13:16

We theoretically should be getting these Carrington class

13:18

events every thousand

13:21

years or so. And

13:23

scientists have been able to look

13:25

through tree rings to see evidence

13:27

of past solar flares. And they've

13:30

found some really incredibly powerful events

13:32

that have happened, say for

13:34

the past 10,000 years. I think

13:36

there's six events. And the scary

13:38

thing is the Carrington event isn't

13:40

one of them. So the Carrington

13:43

event wasn't powerful enough to

13:45

sort of have the evidence of that event be

13:48

locked into the tree rings. So

13:50

back to your question, you know, any thought on

13:52

the lack of impact? We

13:54

get hit by solar storms all the time that a

13:56

8.6 is

13:59

nothing. We saw one

14:01

about 20 years ago. We've

14:04

seen more powerful ones hit Earth, and

14:07

we know what the effects are. There can

14:09

be local damage where satellites

14:12

can go down or some electrical grid can fail,

14:14

like the one that happened in Quebec back in

14:16

the 90s. But

14:19

just in general, it's just not

14:21

a severe enough storm to

14:24

cause significant problems. So we're

14:27

approaching solar maximum. We should see

14:29

many more of these solar storms

14:32

over the coming months leading

14:34

up to whenever solar max peaks sometime

14:36

this year. So this is

14:38

your chance to see auroras. I wouldn't be

14:41

worried at all about what effect. And I

14:43

know, like I

14:45

was arguing with people in my comments saying

14:47

like, this is it, this is the end

14:49

of the world. No, it's

14:51

not, it's not, it's

14:54

fine. Just

14:56

like the asteroids aren't gonna be hitting

14:58

Earth, that

15:00

there are channels on

15:04

YouTube that are trying

15:06

to freak people out for clicks. I'm

15:09

not one of them. I'm trying to calm

15:11

you down for clicks, trying

15:13

to educate you for clicks. So yeah,

15:18

powerful flares happen all the time. No,

15:20

we do. Enjoy the

15:22

auroras. Tom Hodder, if

15:25

Planet 10 exists and is 300

15:27

astronomical units away, would it be

15:29

visible with light telescopes? So

15:32

like that you said, Planet 10, I

15:34

think the Pluto is a planet

15:36

community are gonna appreciate the fact that you're

15:39

saying and calling it Planet 10 and not

15:41

Planet 9. Planet 9

15:44

is the planet that Mike

15:46

Brown and Konstantin Batien are

15:48

proposing as a maybe

15:50

Earth-sized world, maybe Neptune-sized world orbiting

15:52

in the outer solar system and

15:54

its influencing object in the Kuiper

15:56

belt. No one has directly observed

15:58

it yet, but based. on its

16:00

influence, it's kind of narrowing down the

16:02

search space for where this thing could

16:05

be. And the reason

16:07

it hasn't been found is because

16:09

it is very dim. So there are

16:11

plenty of surveys of the

16:14

entire night sky that have been done

16:16

to a depth, a

16:18

sort of dimness of object that

16:20

would have turned up Planet Nine

16:22

at a specific brightness. It

16:24

hasn't been found. More detailed searches

16:26

at even sort of fainter brightnesses

16:29

have been done in the plane

16:31

of the ecliptic, in the places

16:33

where Mike Brown and Constance

16:35

Batien are proposing this object might

16:37

be. But a telescope that can

16:39

make this kind of observations, field

16:41

of view, is very, very

16:43

small and these telescopes are very,

16:45

very busy. So you can't just

16:47

say, listen, we need to use

16:49

the James Webb Space Telescope and

16:51

we need to search the entire

16:53

plane of the ecliptic for a

16:55

mysterious object that is out there.

16:59

Sorry to anybody else who ever wants to

17:01

use James Webb ever again. So just to

17:03

give you a sense, right? The Hubble Space

17:05

Telescope has been operating for almost 35 years

17:08

now and it has probably imaged half

17:11

a percent of the night sky. One

17:14

half of one percent. So it's a big

17:16

sky and it's a very small tube that

17:18

is kind of look at it. And

17:21

so just there are telescopes

17:24

here on Earth and telescopes in

17:26

the space that can see to

17:28

ludicrously faint magnitudes if they

17:30

know where to look. And this is

17:32

the problem. Nobody knows where to look

17:34

exactly. So we're waiting on

17:36

the next great observatory to

17:39

come online and this is Vera Rubin,

17:41

which comes online in 2025. So next

17:45

year, Vera Rubin comes online and this telescope

17:47

is going to be doing all

17:50

sky observations from the Southern Hemisphere and that will

17:52

include the entire plane of the ecliptic, all the

17:54

places where the planets go. It's going to be

17:56

able to observe to a very faint magnitude and

17:58

because it's going to be the

18:00

entire sky every three nights or

18:02

so, any object like

18:05

Planet Nine that is slowly

18:07

moving through the sky, you're

18:10

gonna see its motion every three nights, it can

18:12

be this little dot that appears in the next

18:15

image, the next image, in the next image. It's

18:17

out there or it's not, right?

18:20

And so if Vera Rubin

18:22

does this observation and it doesn't

18:24

find anything, then

18:26

we know that there's

18:28

some other interesting

18:30

influence that is causing the motions of

18:33

these Kuiper Belt objects. There's a lot

18:35

of really great ideas, like maybe a

18:38

rogue planet passed relatively close to the

18:40

solar system and disturbed all these planets.

18:42

Maybe there's just this combined influence from

18:45

all the stars in our neighborhood of

18:47

the Milky Way that is causing this

18:49

change in distribution of the Kuiper Belt

18:51

objects. So whatever the answer is, it's

18:54

gonna be really interesting. Now

18:56

would you be able to see it with a telescope, like a

18:58

backyard telescope? And I would say no. If

19:00

you have a very powerful backyard telescope,

19:02

you can see Pluto, but

19:05

you would need something that

19:07

is like a professional science-grade

19:11

telescope, something into several

19:14

meters across to be

19:16

able to see an object as faint as

19:18

how faint Planet 9 is going

19:20

to be. But the most powerful telescopes on Earth,

19:23

the very large telescope, the extremely large

19:26

telescope, and of course space-based telescopes like

19:28

Hubble and James Webb will be able

19:30

to see it. Like

19:33

unless it's incredibly dark and incredibly

19:35

dim, we'll find it.

19:37

Vera Rubin will find it and then everybody

19:40

else will observe it so

19:42

much. If you

19:45

want to support the work we do

19:47

at Universe Today, consider joining our Patreon

19:49

Club. Now there's something that I want

19:51

you to know, which is that you

19:53

don't have to give us money to

19:55

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join our Patreon for free, you can

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20:03

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20:05

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20:12

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20:14

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20:21

I want to thank everyone who's already subscribed

20:23

and welcome to our recent newcomers. Thanks to

20:25

Ken Paulus, Arnold J

20:27

Ladwig, Marius Daniel, Frederick

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Expansion, Nautilus Studios, and

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Alaskan Stout. Join the club at

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patreon.com/universe today. Moonwalker,

20:44

does the scientist always get exclusive use

20:46

of James Webb or can multiple scientists

20:48

use it simultaneously if what they're observing

20:50

is pointing in the same general direction.

20:53

So the time for James Webb

20:55

is broken up into kind of

20:57

two, maybe three broad categories. So

21:00

the first category is dedicated time

21:02

and the important thing to remember here

21:04

is that using the James

21:06

Webb telescope is completely free. So

21:09

anyone on earth from any country can

21:11

access James Webb and use

21:14

it for free without having to pay anything. Now

21:17

you're gonna have to be a astronomer or

21:19

scientist to make a good case for them

21:21

to grant time on the telescope but you

21:24

know there's a process for scientists to be able

21:26

to go through this. And so

21:28

the sort of the first bucket is the

21:31

people who want to make some very specific

21:33

observation. Like think about how David Kipping is

21:35

going to search for exomoons. He's got a

21:37

very specific planetary system that he wants to

21:40

point at a very specific time when the

21:42

planet is going to pass in front of

21:44

the star. That's the moment to try and

21:46

observe to see if there are exomoons there.

21:49

And so the telescope

21:51

team has granted the time and in

21:54

that exact moment James Webb will turn

21:56

and point and gather that data. And

21:59

I don't remember exact percentage of the time.

22:01

But let's say a third of James Webb's

22:03

telescope time is taken up

22:05

by these direct observations. And so the

22:07

astronomer who has made the request made

22:10

the proposal, then gets a login to

22:12

a website where they can download all

22:14

of their data. And they've got a

22:16

year to have exclusive access to the

22:18

data that they requested to be able

22:20

to write their science paper and be

22:22

able to publish their results. And after

22:24

that year comes up, all of their

22:26

data is freely available to the rest

22:28

of the of

22:30

the internet, and anyone who wants to

22:33

come to that data and see if they can make

22:35

their own discoveries and observations. The

22:37

second tranche of observing

22:39

time is for surveys.

22:42

And so there's a bunch of surveys, one

22:44

called jades, one called seers, there's

22:46

a bunch of stuff that's being done inside the solar system,

22:49

you know, an extra galactic stuff, planetary

22:51

systems. And with these, there's a list

22:54

of targets that are agreed upon in

22:56

advance, essentially, James Webb is making its

22:58

own mini version of the

23:01

Hubble deep field, it's got a specific

23:03

region in the sky, it's taking a

23:05

bunch of images, and then those images

23:08

are being freely accessible

23:10

to astronomers anywhere, you can

23:12

go log in, gather data,

23:15

do with it what you will. And the

23:17

last part of this is called

23:19

discretionary time. And so there's

23:22

some time that's left over. And

23:24

it's a fraction of the leftover

23:26

time that is available by

23:29

by the committee that's running James

23:31

Webb, if something exciting comes up,

23:33

it needs to be observed right

23:35

away. So you think about comets,

23:37

or interstellar objects, or interesting storms

23:39

that happen, or if

23:41

a supernova is seen and requires observations, then

23:44

James Webb can join in the fun and

23:46

be able to, you know, be turned and

23:48

pointing at that object. Now, if it was

23:50

right in the middle of when David

23:53

Kipping was trying to make his actual moon's observation,

23:55

then the, you know, things are gonna have to

23:58

be shuffled around, you know, top of the sky. is

24:00

going to have to be reallocated depending on what happens.

24:02

But yeah, so in

24:04

general, either you get

24:06

exclusive use to the data based on what

24:08

you've observed, but then you have to share

24:10

the data with the rest of the astronomers

24:12

after a year, called an embargo, or you

24:14

are part of

24:17

a larger survey and yeah, multiple

24:19

scientists, everybody can

24:21

access the data immediately. Michael

24:24

Brown, aren't neutrinos a form of dark

24:26

matter particle? So neutrinos

24:28

don't explain dark matter, but I

24:30

really love neutrinos as a way

24:33

to wrap your mind around what

24:35

kind of particle dark matter is.

24:38

And so when astronomers were starting to figure

24:40

out how fusion worked in the sun, and

24:42

they did the math, they said, okay, you've

24:44

got a bunch

24:46

of hydrogen atoms, they're getting smurched

24:48

into helium atoms, and they're releasing

24:50

gamma radiation, if you like carry

24:52

the one, then there's like a

24:54

little bit of mass that

24:57

is missing. And they

24:59

said, so there should be some kind of

25:01

particle that is being released that is getting

25:03

rid of this remainder of

25:05

the fusion process. And yet we

25:08

don't see these particles, we don't

25:10

see like little bullets flying

25:12

out of the sun, tearing everything

25:15

apart, what's going on. And

25:17

so they searched for this object, and

25:20

they built larger and larger detectors,

25:22

neutrino detectors, and realize, over

25:25

time that these particles just

25:27

never interacted with anything. And

25:30

it wasn't until they I think, had

25:32

built this giant neutrino observatory,

25:35

next to a nuclear reactor, and they

25:38

had like a high concentration of neutrinos

25:40

that were passing through it, that they

25:42

were able to start actually detecting the

25:44

occasional interaction with a neutrino and

25:46

the water. And we now know

25:48

that a neutrino will gladly pass

25:51

through a light year of solid

25:53

lead without interacting at all, and

25:55

that there are countless neutrinos streaming

25:57

through your body right now. And

26:00

And yet you don't feel them because they

26:02

just don't interact. And so the kinds of

26:04

detectors that are required to find neutrinos are

26:06

a cubic kilometer of

26:08

water ice down in Antarctica. That's

26:11

the ice cube facility. And so

26:14

we already have an example of

26:16

a particle that is produced by

26:19

fusion, by supernovae, by various other

26:21

events that happen in the universe

26:23

that don't interact in any way.

26:26

They are not detectable

26:28

through their interactions with electromagnetic

26:30

waves, and not detectable through

26:32

their gravity, but they're there.

26:35

And it was finally with the right

26:37

kinds of experiments that were developed. And

26:40

it took decades for people to finally

26:42

go from this theorized particle to this

26:44

actual particle that was found. And

26:47

dark matter is kind of exactly the

26:50

same in that process. Now, its

26:52

behavior in the universe is very different. It

26:56

doesn't interact at all through

26:58

electromagnetism, despite, it

27:00

doesn't interact. It's not getting

27:02

caught in giant neutrino detectors,

27:04

although people have been trying. But we

27:06

can definitely see its influence through gravity.

27:09

And it doesn't interact with itself, which

27:11

neutrinos don't interact with themselves either. But

27:14

where things kind of differ is

27:16

that neutrinos are moving just

27:18

shy of the speed of light. So

27:20

they're considered hot. And

27:23

whatever dark matter is, it has

27:26

to be moving slow because it sort of

27:29

holds itself together in these giant blobs around

27:31

galaxies. And if it was moving at close

27:33

to the speed of light, then it would

27:35

be escaping the gravity of the galaxy, and

27:37

it would be flying off into the universe.

27:39

And so whatever this particle is, it doesn't

27:42

interact with regular matter. It doesn't

27:44

interact with itself. Dark matter

27:46

doesn't collide with itself. But

27:48

it's slow moving and

27:51

must be massive. And

27:53

so over time, that's what astronomers have been

27:56

able to work out so far. They've been

27:58

able to narrow down the search space. But

28:01

no, neutrinos can't account for dark matter

28:03

because neutrinos are hot. They move too

28:05

fast. They don't explain the observations that

28:07

are made for dark matter. So there's

28:09

like another totally

28:11

mysterious particle in the universe out

28:13

there for us to find. Australian. The

28:16

aurora here in Australia look pink and the northern lights are

28:18

very green. Is that true? And if so,

28:21

why? The color of the auroras

28:23

can be anywhere from pink to

28:25

purple to green to blue, red

28:28

definitely. And so they can sort of

28:30

run across the entire color

28:33

spectrum. And it's not

28:35

whether it's an Australian thing or whether it's a

28:37

North American thing. It just depends on what you

28:39

see. So the most

28:42

amazing auroras that I've ever seen were

28:45

green, just only

28:48

green and just have amazing

28:50

shimmering curtain of

28:52

green that went all the way across

28:54

the entire screen. The

28:56

sky. And

29:01

yet other times I've seen red auroras. I

29:03

saw one that was like a line of

29:05

red that went just all the way across

29:07

the sky and this sort of line that

29:09

just hung there. And

29:11

we'll show you some pictures. We showed them in

29:13

space place, but I was in Japan. I wasn't

29:15

able to see it, but my wife was back

29:17

here in Canada and she was

29:20

able to watch the aurora and she got

29:22

all of the various options. She got

29:25

some green aurora and she got some

29:27

sort of pinkish red aurora with bits

29:29

of yellow in it. Amazing.

29:31

And this was all these are pictures just off

29:33

of her iPhone. And yet she was able to

29:35

see them with this level of clarity.

29:39

So this last batch of auroras, like if you

29:41

missed it, like me, this

29:43

was a really great chance to see auroras and hopefully

29:45

we'll get a chance to see more. So no, there's

29:47

no rhyme or reason to who gets which colors where.

29:50

Lily Rose, what is the Drake equation? How do you think

29:52

it goes with the length of the universe? So

29:55

the Drake equation is an equation

29:57

that was put together by Frank.

30:00

Drake and he did

30:02

this as a sort of talking

30:05

point for a conference

30:07

that a bunch of scientists were having

30:10

where they were trying to consider and

30:12

work out how many technological civilizations there

30:14

are out there in the universe. And

30:16

so Drake proposed

30:18

six factors. And

30:21

I forget the exact precise factors, but the

30:23

gist is the number of stars

30:26

with planets habitable planets in the Milky

30:28

Way and the percentage of those planets

30:30

that are within the habitable

30:32

zone and the percentage of those that have

30:35

life that emerged on them and the percentage

30:37

of those that have had a technological civilization

30:39

and the length of time that those civilizations

30:41

last and the amount of information

30:44

they've communicated out into

30:46

the universe. And that

30:48

if you crunch all those numbers together, you

30:50

can calculate the number of communicating civilizations that

30:52

are in the Milky Way. And people come

30:55

up with different numbers like I found a

30:57

thousand, I found one, I found 10 million.

30:59

And so the problem is that, yeah, we

31:01

might know what percentage of

31:03

stars have planets, what percentage of stars are

31:05

terrestrial in nature, what percentage of those are

31:08

in the habitable zone that we're getting to

31:10

that part. But it's the how often does

31:12

life form? We don't know. We could

31:14

be anywhere from every single

31:17

planet life forms to it happens one

31:19

in a quadrillion times, which means that

31:21

we are the only life in the

31:23

entire observable universe. And so we just

31:26

don't know. And when you look at

31:28

the Drake equation, you can magnify and

31:30

multiply it, you can think, well, like

31:32

what percentage of those habitable

31:35

planets have plate

31:37

tectonics, which is required for multi

31:41

cellular organisms, what percentage of them have

31:43

a large moon in a stable orbit

31:45

to keep its orbital tilt from

31:48

being unbalanced? And what percentage of them

31:50

are located within the habitable

31:52

zone of the galaxy? And so

31:54

there, there could be another 1000

31:56

factors that will influence the

31:58

chance of an entire. civilization

32:00

arising and communicating in the universe.

32:03

But we just don't know those

32:05

numbers. That one number on

32:09

how many worlds has life arisen

32:11

is still a mystery.

32:13

And until we find any other

32:15

examples of life out there in

32:18

the universe, we just don't know.

32:21

And so, unfortunately,

32:23

as cool as the Drake equation is,

32:25

and as like tantalizing

32:30

a thing that it purports to deliver,

32:32

right? Just run a bunch of numbers

32:34

through and you will get the number

32:36

of communicating intelligent civilizations in the Milky

32:39

Way. Just like that. Now we just have

32:41

to find them. Well, the

32:43

problem is that it's garbage

32:45

in, garbage out. And so if

32:47

you're just gonna guess, then

32:50

why do you need an equation to guess? Just guess. Come

32:52

with a number, whatever number makes you the happiest. So,

32:56

unfortunately, more data needed. Edward

32:59

Hinton. They say that you wouldn't know

33:01

that you've passed over the event horizon of a huge

33:03

black hole. So you can see the event horizon of a

33:05

black hole and partially put your arm over it, what

33:07

would happen? So for the

33:09

small black holes, the stellar mass black

33:11

holes, then the tidal forces are

33:14

so extreme that they're gonna tear your arm apart

33:16

and tear your whole body apart as you get

33:18

too close. So you will know that you are

33:20

approaching the point of no return when you have

33:22

been stretched into a

33:24

stream of goo that is now

33:27

orbiting around the black hole and

33:29

on its way to go in.

33:31

But for the supermassive black holes,

33:35

the ones that have millions or maybe billions of times the mass

33:37

of the Sun, the gradient of

33:39

the gravity that you experience is

33:41

so low that you can fly

33:43

your spaceship through the event

33:46

horizon and not even feel it. And yet

33:48

there is no escape. You have passed the

33:50

event horizon, you can never come out. And

33:53

so what would happen if

33:56

you flew right next to the event

33:58

horizon and you put your arm into

34:01

the event horizon. Well, the part of your

34:03

body that is outside the event horizon could

34:06

theoretically, if you're able to move your spaceship

34:08

at close to the speed of light, could

34:10

escape. But the part of your arm that you

34:12

put into the event horizon is going into the black

34:15

hole. It is a one-way trip. You do not come

34:17

back out. So, it doesn't

34:19

matter. Whatever you try to come

34:21

up with, take a

34:24

camera, put it on a long pole, stick it

34:26

down into the event horizon, and then pull it

34:28

back out and you're like, there's no camera there

34:30

anymore. It's just gone because nothing gets

34:33

out. All roads

34:35

lead to the singularity and there is no, there's

34:37

no way around it. So,

34:40

just inside the event

34:43

horizon, going into the black hole. Outside

34:45

the event horizon, there's a chance you could escape.

34:48

All right, those are all the questions that we got this week. Thank

34:50

you everyone who joined me for the

34:52

live show and asked me questions live

34:55

here on the channel, as well as

34:57

everybody who posted their questions into the

34:59

YouTube comments. So,

35:01

I really appreciate that. Now, we record

35:03

this show live every Monday at 5

35:06

p.m. Pacific time. So, if you want

35:08

to have a much longer two-hour experience

35:11

of the question show, come join us. There'll be

35:13

a notification here on the channel. Subscribe to the

35:15

channel. Click on the notifications bell and you'll be

35:19

informed when we go live next

35:21

Monday. Now, I'm going to

35:23

talk about my recent trip to Japan,

35:26

but first, I'd like to thank our

35:28

patrons. Thanks

35:30

to Abe Kingston, Andrew Gross, David Guilterman,

35:32

Dennis Alberti, Dustin Cable, Jeremy Madder, Jim

35:34

Burke, Jordan Young, Josh Schultz, Madzo, Paul

35:36

Robach, Stephen Krasocki, Stephen Feiler-Munley, and Vlad

35:38

Shifflin, who support us at the Master

35:40

of the Universe level, and all our

35:42

other patrons. All your support means the

35:44

universe to us. So,

35:47

you're probably wondering what happened to the question show

35:49

for the last two weeks and that's because I

35:52

was in Japan with my son. Now, this trip,

35:54

originally we were going to take four years ago

35:56

in March 2020, but... then

36:00

the pandemic hit and so we had to cancel the

36:02

trip and so we waited and now we finally were

36:04

able to do it and I am so glad we

36:06

got a chance to go back. Now

36:09

we didn't do any spacey-sciencey

36:11

stuff, it was more going and

36:13

seeing temples and shrines and eating

36:15

amazing ramen and riding

36:17

on bullet trains and just having a great time but

36:20

I'm so glad that I went and sort of thanks

36:22

to everybody who we got a chance to hang out

36:24

with in Japan. The hospitality

36:27

of the country is incredible and just

36:29

with the level of culture and organization

36:31

and the food. So if you're wondering

36:33

like, oh I kind of am intrigued,

36:35

I like anime, I'd like to maybe

36:38

go to Japan, do it. It's

36:41

such an easy country to travel in. Distinguish

36:44

on all the signs, you

36:46

can, most machines that you can access, you can

36:49

switch to other languages. Everybody

36:51

is very warm and generous and

36:53

the prices are reasonable

36:56

now which I know is sort of

36:59

hard for the Japanese economy but for a

37:01

person who is coming from another country, your

37:03

dollar goes pretty far. So I'm

37:06

gonna go back pretty soon, I

37:09

think. Take my other

37:11

kid to Japan for a different

37:13

adventure. So anyway, we're back

37:16

with the show and I

37:18

hope to go back again and do more

37:20

traveling. All right, we'll see you next week.