May 14, 2020 • 43 mins
Daniel and Jorge answer listener questions about the smallest, biggest and cataclysmic-ist things in the Universe!
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Episode Transcript
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Speaker 1 (00:08):
Daniel, do we get a lot of interesting questions of
the podcast, you know, through email or Twitter? Oh, we
get the best questions. I'll be honest. It's my favorite
moment of the day when I see a new question
come in from the listener line. All right, cool, So
tell me how do you decide when to answer a question.
Do you reply to them on the email or do
you wait until we talk about it on the podcast. Well,
(00:28):
I feel like these listeners want to know the answers.
So if I know the answers, I write them right back.
And if you don't, then I gotta go off and
do a little bit of research. And that's how a
question ends up on the podcast. I see you think
I know the answer, that's right, I'll ask a real expert.
It's basically, it's just a big stalling tactic when you're stumped.
That's right. Listeners are very smart and if they ask
(00:51):
me a hard enough question, it will end up on
the podcast. Hi war handm cartoonists and the creator of
pH D Commons. Hi. I'm Daniel. I'm a particle physicist
(01:13):
and I've often been stumped by listener questions. Welcome to
our podcast, Daniel and Jorge Explain the Universe a production
of I Heart Radio in which we take you on
a mental tour of the universe, all the things that
science has figured out, and all the things that science
is still puzzling over, all the things we know and
all the things we want to know, which is basically everything,
and that's right. We take you to the limits of
(01:33):
the curiosity of scientists and also to the limits of
the curiosity of our listeners. People would like you who
are listening to this podcast, who have questions about the universe,
about the cosmos, about our planet, and about the things
that make up who we are. Because being curious, it's
just part of being human. Wondering how this whole thing works,
how this amazing and crazy universe came to be, how
(01:53):
it's put together, and what its ultimate fate will be.
That's just part of being human. And so we think
that wondering and curio pocity belongs to everybody, and we
want to bring you to the forefront of knowledge. And
often we talk about the kind of questions as scientists
are asking about the universe, but sometimes we talk about
your question and mac question, Daniel is I'm curious about
how we still have a podcast who gave a couple
(02:15):
of introverts a platform this big to talk about the
small thing that is to you. Well, it just cost
us a few bananas a week, so I think that's
the that's the reason. Well, bananas are hard to come
by these days, you never know. But yeah, welcome to
our podcasts and sometimes in this podcast we love to
answer listener questions. So if you have a question, you
can send it to us via questions at Daniel and
(02:35):
Joorhead dot com or through our Twitter account. In it
that's right, I'm pretty good at monitoring the Twitter page
and answering listeners questions. In fact, it's the way I
take a break from my day working on something hard.
I'm gonna go take a break and answer some fun
listener questions. Yea, and sometimes you pay questions to answer
on the error. And so today on the podcast, we'll
be tackling listener question number ten, particle stars and universe
(03:03):
size black holes. And these are some of my favorite
episodes because I love understanding what the listeners are thinking
about and what they are wondering about. The reason that
we do the person on the street interviews is it
because we want to take the pulse of current knowledge.
What are people understanding? What are they confused about? Because
we want to educate them right there. We want to
take them and unravel those points of confusion, help them
(03:25):
have that moment of clarity of understanding when things click
into place. And another way to do that is to
have the listeners ask us directly something that they are
wondering about. And when we get a question that I
think is especially clever or hard to answer immediately, but
I think other people will want to hear the answer to,
then yeah, we put it on the podcast. Yeah. Do
people get a reward if they stump you, Daniel? You
(03:47):
send them about cracker Jack Prize. Yeah, I'll send you
a list of people you need to send cracker Jack
prizes to put that on your to do list. It's
the permit scheme for the universe. They just get the
joy of knowing that they've asked a really good question.
And you know, we've got a lot of wonderful questions.
We get questions from five year olds, we get questions
from nine year olds, and all of them just reflect
(04:07):
this desire to understand, to not live in confusion, but
to have all the pieces of the universe fit into
place in their minds, and that's my goal too. That's
everybody's school. Yeah, and we get pretty good questions, and
especially the ones we're going to cover today, I thought
they were pretty cool. I was like, Wow, I don't
think I know the answer to these questions, which is
not saying a lot I know, but still, I've been
(04:27):
hanging out with you for a couple of years and
I feel like I don't really know the answer to
these questions. Well, you know, I feel like you're a
deputized physicist. I've heard you answered physics questions when I
haven't been around. I thought that's a solid answer. Wow, yeah, yeah, yeah, Wikipedia,
thank you no. On our live stream, Remember, I got
dumped off for five minutes and came back and you
(04:48):
had totally answered a bund of physics questions, and I thought,
maybe I'm not even needed around here anymore. I've, you know,
I've made myself obsolete by teaching you enough physics. I
think I can probably handle answering a question. I just
can't hand the follow up questions. I'm guessing it's probably
when you know you need to call them real physics.
But today we have some really great questions about how
(05:08):
new stars forming, the guy about the large Hadron collider detector,
and about basically everything and the Big Bang and the
fate of our universe? Did they include also the meaning
of life? How much of the universe can you roll
up into one question? I think our third question today
might take the case, well, you know, you get one shot,
you might as well roll it all up into one big,
(05:29):
fat question. All right, Well, let's get into it. Our
first question comes from Meredith, and Meredith has a question
about the night sky. Hi, Daniel and Jorge. My name
is Meredith, and I've been wondering if new stars are
always appearing in the night sky and how do we
know if they're newly formed stars or if they're so
far away that their light has only just reached us. Thanks, alright,
(05:50):
awesome question, Meredith. I guess? Or question is this? I
guess does the night sky change, like do we get
new stars forming and disappearing all the time or is
it pretty much set in the I guess lifespan of
a human. Yeah, it's a wonderful question because it reflects
on these differences between like human scales and human time
length and cosmological timeline I'm getting the sing as you're
(06:12):
gonna say, No, the night sky is not static. No,
it's only static on the short little blip of life
that we live. Right. The universe has been around for
much much longer than a human life or ten human lives,
or a thousand human lives or a million human lives.
And that means that if you watched it on like
time lapse, it would seem really active and chaotic. It's
(06:33):
like a frothing puddle. Right. We're living sort of like
in slow motion, where the universe and the galaxy seem
like frozen in time, but in reality they're not. Yeah,
And we have the ability to sort of look back
into time, right, and also the ability to kind of
project forward to sort of get a broader sense of
the history of the Like, imagine that you were something
that lived just a brief millisecond and you live that
(06:56):
entire lifespan, that tiny little mill second inside an exploding
grenade or something, or you know, a rock dropping into
a puddle of water. It wouldn't seem very chaotic to
you because on that millisecon, not that much happens. You know,
things don't move very far, don't change very much. And
so that's our viewpoint of the universe. We live this
little brief lifespan inside a vast, very slow moving explosion.
(07:21):
But if you watched it happened at a faster pace,
you could tell that there are things bouncing off each other,
there's new stars forming, there's all sorts of crazy stuff
happening on the universe time scale. I was gonna say
it's it's like hitting the fast forward bund, but nowadays
we don't have fast forward buns. We just have like
skip ten seconds funds. And that wouldn't be already Netflix
(07:42):
that want to be very satisfying, would it? If you
skip the intro of the universe, you missed most of
the exciting style. Well, what if we are just living
in the intro of the universe. This is just the
credits and the drama hasn't even really begun. Somebody's gonna
skip us. Don't skip us. No, I feel bad every
time I skip the intro. That because somebody spend time
making that you watch it at least once, you know,
if it's more than fifteen seconds, then then I skip
(08:04):
it every time. All right, Well, I guess the question
is does the Nights Guy change and specifically, do we
get new stars in the nice guy? Like, could you
could I be watching this guy one of these nights
when I'm out in the wild or camping and suddenly
like a new star which shine that wasn't there before
and nobody in human history had recorded it? Is that possible? Yeah,
it's a fascinating question, and I think to understand that
(08:25):
we have to think about, like how stars are made.
Let make me think about how often that happens, and
also what fraction of the Milky Way we can actually see,
and those pieces together will help us answer this question,
like what are the chances of that happening? Depends on
all these different factors. Yeah, exactly, And so we have
to remember that, like how are stars made. It's not
like somebody just goes along in the simulation the universe
(08:47):
and runs some subroutine that says make new star. Like,
it happens through a process and it starts when clouds
of gas collapse. Okay, so let's get into star formation then.
So stars, you're saying, form when the cloud of gas
out there in the universe crunched together. Yeah, and the
Milky Way surprisingly is filled with these clouds. Our galaxy
is a bunch of stars in its dark matter. But
(09:07):
there's also sort of the raw materials of stars just
floating around there, these vast clouds of gas. They're like
seventy hydrogen and each one has like millions and millions
as much mass as our sun. They're like, you know,
a hundred light years wide, and there's thousands of these
things just sort of floating around the Milky Way capable
of making stars. It's like the raw on form basic
(09:30):
material of stars just waiting to be you know, brought
together by gravity. Yeah, it's like your star pantry, right,
It's all the ingredients needed, but just not in the
right arrangement. Okay. And so then eventually these clouds kind
of collapse because of gravity, and then that's how stars
get for Yeah, And there's a few ways that can happen.
One is they just get big enough. You know, they
slowly accumulate enough stuff that eventually their heat and their
(09:53):
pressure can no longer keep them from collapsing. Right, Gravity
is always working to pull stuff together, but if something
is hot enough, you know that it won't collapse. Like,
why isn't our atmosphere just collapsing into little stars all
the time? Because it's got energy, right that overcomes that
gravitational pull, like it wants to expand kind of. Yeah,
it's velocity is too great for gravity from the other
(10:14):
part of the atmosphere to pull it together. But if
the gas gets heavy enough, right, there's enough mass and
it's cold enough, then it can collapse. The gravity will
take over and just collapse it. And so that that
happens a lot in the in our Milky Way galaxy,
or does it happen because I guess maybe what you're
saying is that most of the stars we see when
(10:35):
we look at it out into the night sky come
from our Milky Way, So we should focus just on
sort of how stars form in the Milky Way. Yeah,
that's right. When you look at in the night sky,
you're looking at the stars in the Milky Way, you're
looking through the Milky Way out into the rest of
the universe. And if you had a really good telescope,
then you could see other galaxies also. They would show
up looking mostly like stars, unless your telescope was super awesome,
(10:56):
and you could tell that they had different shapes. And
you know, it's only like a hundred years ago that
anybody understood that those little blobs were entire other galaxies.
But yeah, most of the stars that you can see
are actually just stars in the Milky Way. Okay, so
we have these clouds and they're making stars. But can
you see these clouds in the night sky or the
daytime sky or are these pretty sort of hidden from us? Well,
(11:17):
if you ever see the band of the Milky Way,
like sometimes on a really clear night when you're going camping,
you see a bunch of stars and then you see
sort of this milky way in the sky. Right, that's
an accumulation of stars, but also gas and dust. That's
where new stars would come from, and that's where new
stars come from. That's the plane of the galaxy. That's
the densest region of the galaxy that you're looking at.
(11:38):
And you know, this is one of these the Orion
nebula in the direction of Orion is of a light
years away. It's capable of making stars. And you know,
we don't quite understand the whole process of how this happens.
Sometimes it's just gravitational collapse. Sometimes these clouds could collide
and the points of friction provide the sort of the
impetus to make the cloud collapse. Sometimes we think it
(11:59):
might be like a super nova went off and that
energy sort of triggers the cloud to collapse. It's not
an inevitable thing for a star to form out of
a cloud. You gotta kind of trigger it. Yeah, if
the cloud gets big enough and dense enough, or if
something comes along and strikes it, Yeah, then it can.
Then it can happen. Okay, I guess then if you're
not looking at the milk away, then is it possible
(12:19):
that a new star will form kind of like out
of the blue in between the stars. And if you
look the other direction, if you're not looking in the
milky way, they know, like, there aren't these clouds to
make stars out between galaxies. So it's really just only
in our galaxy that we could see a new star
be born. There are other galaxies that make their own
new stars also, but it's really hard to see a
single star inside another galaxy. That's really pretty tricky. So
(12:41):
it only really sort of be in our galaxy. And
when these collapses happen, they don't just like make one star.
You're talking about a cloud that's capable of making lots
and lots and stars at once. And so when the
collapse happens, you get a bunch of stars twins or
much more than that. Yeah, exactly. I don't even know
what the Latin word for that would be, but you
could get thousands of stars forming basically at the same time. Wow,
(13:04):
I see their stars are made in batches. Yeah, stars
are made in batches, just like cupcakes. Right, You don't
make one cupcake at a time and then they go
off into the galaxy, or do they? You know, is
it possible to that a star gets made somewhere and
then moves in another place, or is it pretty much
all condensed and concentrated in the center of the Milky Way.
It could happen also two different parts of the Milky
Way wherever one of these clouds are. And after the
(13:27):
gas collapses and forms the star, it doesn't change the
overall gravitational trajectory of that mass. And so whatever the
center of mass of that material was doing, probably orbiting
the center of the galaxy is what it will continue
to be doing. So these guys will be bound together
in their fates. They will be near ish each other,
sort of in the vicinity, but they may end up
getting spread out later, but initially they'll be moving together,
(13:49):
all right, So then what sort of the rate or
like how many new stars get made this way per
per day or per year. It's hard to say like
per day because it's pretty stochastic, like for this to happen,
clouds have to collide or a supernob has to go
off for the cloud has to reach the right critical
density or something. So it's easier to talk about sort
of averages. And you just think, like, how long has
(14:11):
the Milky Way been around, Well, about thirteen billion years,
and how many stars are there? Right, and there's a
hundred billion stars, right, and so that means that roughly
about every forty seven days in the history of the
Milky Way, a star has been made. Now, it's not
like every forty seven days a new one turns on.
(14:31):
You know, you get a thousand made, and then you
might go years and years before another one is made.
Then you get another thousand. But on average it's every
forty seven days. It's like Los Angeles star is born
every forty seven days, and a sucker is born every day.
There's a lot more suckers than stars. Yeah, exactly. Okay,
So an average, the Milky Way makes like one star
(14:53):
every month and a half. Yeah, one star every month
and a half. That's its rate of production. And you know,
the Milky Way is a big place, so that's not
a whole lot of new stars. You know, one star here,
another star could be on the other side of the
Milky Way. It's like a hundred thousand light years away.
So it's not that many because we can't see all
of them, right, But I guess of thinking about the
ones that we could see, what would be the rate,
(15:13):
do you think? Yeah, I think people would be surprised
to understand that when you look up at the night sky,
you're seeing a very small fraction of the Milky Way
because most of the Milky Way, the stars are too
far away for you to see them. Like, your naked
eye is not good enough at capturing those photons from
those stars. The stars from the other side of the
Milky Way, they're shooting their light at us, and it's
getting here. But you know, you might get like one
(15:33):
photon per minute. And so if you're looking up at
the night sky with a naked eye, you're only actually
seeing a few thousand stars of the Milky Way. Of
the hundred billion stars in the Milky Way, you're not
seeing all the stars you could be seeing of the
Milky Way. That's right. If you had like two hubbles
for eyeballs, you would see a lot more stars. Right.
It'd be kind of awkward to like getting your car
(15:54):
or walk around, but you'd have a great view at night,
like if my eyes were bigger or I had like
super night vision. Know, I mean, like literally, if you
had two hubbles attached to your eyeballs, you're being literal.
Was being literal, I was fantasizing from like go up
into space, grabbing one of these peas cups and sticking
in your eyes. Imagine what you could see um. And
so essentially that defines like a sphere, you know, nearby
(16:18):
stuff that you could see. So for us to see
a star be born, you would have to be born
fairly close to the earth. And again it depends like
how bright it is. If it's brighter, it could be
born further away. If it's dimmer, and have to be
born closer. And so we could just do a simple
division again and say, well, there's a few thousand visible
stars the Milky Ways, billions and billions of years old.
(16:38):
Do the math, and you get that a new visible
star appears about every million years. Oh, I see. If
I were to look at the night sky, I would
have to on average wait a million and a half
years to see a new star. Yeah, exactly to see
a new star be born. So not likely, not likely,
although you could get lucky. You could watch for ten
(17:00):
minutes and see a hundred stars appear. Right. That could happen,
because you could get a cluster of stars born near
the earth. But yeah, I wouldn't bet on it. You
could win the lottery, it's possible, Yeah, you could. And
she also asked about how do we know if the
stars are newly formed or if the light is just
(17:20):
reaching us? Right, which is another great question. Yeah, like
if I see something from if I am looking at
the next guy and I see something turn on like blink,
how do we know it's a star that formed or
maybe a star that what the form a long time
ago and now I'm seeing it. What's the difference in
her question? Yeah, I think she's asking did the star
just form if it turns on, or did it form
a long time ago and we're just now seeing the light.
(17:42):
And the answer is always the second. It's always that
we're just now seeing the light. And it formed a
while ago. If it formed really close to the Earth,
we'd be in trouble, right, No need another star really
close to the earth. So that means it has to
have formed somewhere far away, which means it takes light
a while to get here. And and she also asks, like,
you know, how do we know? We can measure the
distance to these stars using various methods. We had a
(18:04):
whole podcast about it. We can like look at it
from telescopes from different parts of the Earth and see
it shift, sort of the way you can tell how
far away something is by changing your eyeballs by opening
one eyeball or just the other one. With houbble telescopes,
that would be awesome at telling how far away basketball is.
So we have ways to tell how farstening is away.
(18:24):
And then we can tell this light from this star
that has just arrived since this five million years away,
that means the star formed five million years ago. Okay,
So I guess that the lesson is if you are
seeing a newly formed star in real time, then you're
kind of in big trouble. That's right, because that means
you're we you shoet have war more sun screened. Yeah,
(18:44):
I'd say run, but there's nowhere to run dig maybe.
All right, well that I think that answer is may
this question, which is that new stars are appearing in
the night sky, the answer is yes, but they probably
don't happen that often, maybe every one and a half
million years. So we're sort of blessed and stuck with
the nights guy that we have right now. That's right,
(19:05):
but hey, you never know. I wish upon a star
and maybe you'll see one. All right, let's get into
our other questions. We have more questions here about the
large Hadron collider and what Daniel actually does as a job,
and about the Big Bang and black holes. But first
let's take a quick break. All right. We're answering listener
(19:36):
questions and our next question comes from Hunter from Buffalo, Wyoming,
and he answer a question about what exactly does Daniel
do at this job other than napping. Let's get into it, alright,
and drinking coffee somehow at the same time. I don't
know how you do it. You have the coffee, then
you have the nap. That's the key. Anyway, here's Hunter's question.
(19:57):
Hey you guys, my name is Hunter from Buffalo, A Wyoming,
And my question for you is, how does the detector
at CERN actually work? How does this massive device detect
these tiny, tiny particle interactions? And when they do shoot
particles together, how do they make them hit each other?
(20:17):
I mean, these particles are so small and they're going
in this massive chamber. You figure that there's a chance
that they miss each other. So how do they do it? Thanks?
All right, thank you, Hunter Daniel. I feel like Hunter
is kind of skeptical about your your professional year. He
doesn't seem like it should work. Are you sure that skepticism?
Maybe it's all Maybe it's wonder right. You see, he's amazed.
(20:42):
He's amazed that you have a job. I'm amazed that
I have a job doing this. Sometimes. I mean I
get to like tear apart matter and figure out what
it's made out of. As a job, I feel pretty
lucky and special sometimes awesome. And so his question is
how does the large hadron collider detector actually work? I
guess he's he's sort of wondering about the mechanics because
it seems like, we know, you guys smashed particles together.
(21:04):
But I guess this question is that it seems something
impossible to do, Like, how do you take a pin
and have it hit the head of another pin and
actually see what happened. Yeah, it's a great question, and
it's fascinating because he asked questions about the only two
parts that we can do, which is like, try to
smash stuff together and then look at the stuff that
comes out. We can't actually see the collision itself, right,
(21:27):
this moment of collision when something magical happens will not magical. Obviously,
something scientific happens and the new particle is made. That
moment is invisible to us. But we can try to
control the initial situation, what we're shooting in at what energy,
and then we can try to observe what comes out
the eventual stuff. So the first part is like how
do you shoot these things together and actually make them hit?
(21:49):
And you totally right, Hunter that if you shot one
proton at another proton, you would miss, I mean did again,
you would miss, and you'd miss like a hundred billion
times before maybe you would hit, So that it's not
what we do. Instead, what we do is we fill
our guns with a hundred billion protons and we shoot
it at a hundred billion protons, and we shoot those
little like clouds of protons at each other. I see.
(22:12):
It's kind of like dating. Do you get to do
a lot of swives before you find the right person? Yeah, exactly,
you gotta throw a lot of darts at the wall,
and so here, essentially we're throwing a cloud of darts
against another cloud of darts and hoping that the tips meet.
And you don't just throw a bunch of darts, you
throw like a bazillion darts a bazillion times a second. Yeah,
every twenty five nano seconds, one of these bunches bunches,
(22:36):
the technical term we use for this little cloud of
protons were very fancy. One bunch which contains you know,
a hundred billion protons passes through another bunch, and that's
every twenty five seconds. We do it twenty four hours
a day, three sixty five days a year. And do
you call these collections of protons bunches? Then I know
you're trend is. If you collect particles, that's another particle.
(22:58):
I'm feeling some schmid here now about our naming scheme.
You know, we call those bunches and we collide them,
and you know, it's really it's an amazing engineering achievement
to build this thing, to accelerate the particles to this energy,
to focus those beams to the smallest possible dot, to
maximize the number of collisions we get. And when you
pass a hundred billion protons through another hundred billion protons,
(23:21):
both going and nearly the speed of light, you don't
get a hundred billion collisions. You get like sometimes zero,
sometimes five, sometimes ten, sometimes twenty five collisions. So the
probability is pretty low. It's like five in ten to
the ten. It's very small. Yeah, and the probability gets
better the tighter you can make your beam or the
denser you can make that little cloud, the smaller the
area over which you're spreading those protons. But it's not
(23:44):
very high. And even when we get collisions, mostly those
collisions are pretty boring. It's proton bounces off of proton.
Nothing happens, protons going protons like Billard balls. They just deflect. Yeah,
they just deflect. That's like nine nine percent at the time.
What happens. Usually it's not very exciting. I guess one
proton repels another proton, so they just kind of like
(24:04):
push each other away. Yeah, they're both possitively charged and
they will interact. But that's the most likely thing to happen.
If you're throwing darts at a wall, you know, most
of the spots on that dartboard are proton bouncedself proton.
Sometimes you hit the spot where like it makes a
Higgs boson, or it makes some new weird particle. And
that's why we do it so often, because we're sifting
through so many collisions looking for the rare one that
(24:27):
will help us see something new. We think the weird
stuff is rare, so we have to look at a
lot of collisions to find them. Seems like sifting through
sand for a special grain of sand. Yeah. I think
that's probably a lot like tinder, right, just like you
were saying, it's a lot like data. Um, you're looking
for that one special somebody, and you've gotta look through
a lot of people sometimes to find the one that fits.
And so part of a hunter's question was, first of all,
(24:47):
how do you smash it together? I think you can
answer that, But now how do you tell what actually happened?
You know, because I imagine these are, you know, small
things that smashed together. How do you actually tell what
happened when they smashed together. Yeah, you can't just like
take a video. We'd love to do that, but first
of all, these things happened too fast. So for example,
a Higgs boson or a top cork, if you make it,
(25:08):
it lasts for ten to the minus twenty three seconds
before it turns into other particles, So you just can't
see it. Like, we don't have cameras that are that fast,
and on top of being super duper short lived, they're
super duper tiny, and we don't have cameras that can
see things that's small, and so they're smaller than the
wavelength of light we could use, so we don't see
(25:30):
at all these collisions. They're totally invisible to us. It's
like they happen behind a dark curtain. Instead, what we
see is that what they turned into is you know what,
trot's out onto the stage in front of the curtain. Hre.
It's more like showing up at an intersection after a
car crash and trying to figure out what happened because
we see the remnants, you see, like the bits and pieces. Yeah,
the Higgs or the top or whatever happened will turn
(25:52):
into other particles that do last long enough that we
can observe, and so we look at those we try
to figure out from what's left over, from what was produced,
what actually happened in that exciting moment of collision. And
that's kind of what you see when you look up
pictures of the large Hattern collider. They mostly show you detectors,
like the giant machines used to figure out what came
(26:12):
out of these collisions, like the huge cylinder and the
sort of warehouse size machines and the little tiny people
standing in front of it. That's that's kind of what
you see, right. It's it's the detectors, not the actual
like gun that shoots the proton. That's right. And in fact,
they're totally different communities of people that work on that.
Like I work at SIR and I work on the
l C. I don't work on the accelerator at all.
(26:33):
I have no expertise in building an accelerator. But I
work on a group of people that built the detector
that surrounds this collision point to take some kind of
digital picture of what flew out of it. And that's
what you're describing, these huge detectors. And so this, for example,
I'm in the Atlas collaboration, and there are four places
around the ring where people have built these detectors to
surround it. And so the Atlas Collaboration built the Atlas detector,
(26:57):
and a lot of the other detectors follow a similar scheme. Essentially,
what you're trying to do is take pictures of the
particles that fly out, but again you can't directly image them.
You have to measure somehow their properties. You have to
measure what they're doing. It. It's not just about capturing them.
It's like, oh, it was going this way with the speed,
with this momentum. That's exactly it. And so what we
do is we pass all the particles through a magnetic
(27:18):
field because by seeing how much they curve in that field,
we can measure their momentum and we can also tell
if they had an electric charge or not. And then
we have another layer of detectors that tries to measure
their energy. And so by putting these pieces of information together,
we can sort of tell what the particle was because
everything has a distinct signature, like an electron is a charge.
(27:38):
Particle will bend in that magnetic field and then it
will splash a bunch of its energy in that outer layer,
whereas a photon won't bend in that magnetic field would
be totally invisible, but then it will leave a splash
in the outer field. So we can sort of tell
what was what by piecing this together, but we never
we never get like a picture. It's like, oh, look,
this is the electron that was made. It's all like
we see tracks in the snow and we deduced from that,
(28:01):
you know what ran away. It's like your kid leaving
a mess. You're like, there was definitely a kid here.
There's a bucket of paint's built and I see little footprints,
so I'm pretty sure I know who's here. Delighted here,
and it's done instead of layers, right, Like, I think
that's cool that first you have the magnetic field and
that's how you measure momentum and charge, and then you
have a whole another layer that measures the energy, and
(28:23):
then another layer that measures other things. Yeah, because some
things escape, right, there's the layer that measures energy. It's
job is to slow the particle down to grab all
of its energy in order to measure it. But some
particles get right through there, like a muan will fly
right through. It hardly interacts with that detector, and so
we have a whole other layer of detectors on the
outside to try to bend muans and measure their energy.
(28:46):
So muans get bent twice, one in the inner magnetic
field and then one in the outer magnetic field, and
then some things escape completely, like neutrinos. If they're produced
in these collisions, they're just totally invisible to us. We
can't see them at all. Know, would fly through like
a light year of lead before interacted, So there's no
chance it would interact with our detector unless you put
a light year of lead. Yeah, I'm gonna write that
(29:08):
grand proposal, kind of get a cubic light year of lead, please,
that's right. Then you put it in your eyeballs and
you would be able to see Natrina even if the
n SF said, yes, tod that, Where would you even
source a cubic light year of lead? Like seriously? All right, well, um,
I think that's that kind of answers. The question is
how does the L A C detector actually work? It works,
(29:32):
and it works by amazing feats of engineering where you
take bazillions of protons and smashing bazillions of times a second,
and then using incredible and warehouse size machines. You kind
of track what happens and what comes out of these cours. Yeah,
and for every collision, we read out a hundred million
pieces of information and we do that every million, million,
(29:56):
hundred million. That's for one channel, and each channel can
have you know, bites and bite of data. And so
we have a lot of data coming out of this
thing because it's every twenty five nanoseconds, and so we're
just producing petabytes and petabytes of data and so actually
most of it we throw away. Most of it we
filter it away really quickly because usually it's boring right
to protons collide, to protons come out, that goes in
(30:17):
the trash. So a lot of the stuff that we
do is making rapid keep it or kill it decisions.
And that's kind of what you do, right that that's
kind of your part in this whole giant scientific endeavor
as you used to work on an algorithms that try
to sift through this data and throughout the ones that
we don't need. That's right. Part of being in a
collaboration of like five thousand people, becoming a specialist is
saying I'm gonna do this bit and you do that bit.
(30:38):
And the bit that I personally work on, that my
group works on is this trigger system that makes the
keep it or kill it decisions every twenty five nanoseconds.
And it's not just me it there's a collaboration of
hundreds of people who work on on that one system
in this huge detector filtering the car crash at the universe.
It's sort of terrifying sometimes because if you make the
wrong decisions, you're just throwing it away. Like once I did,
(31:00):
it's gone. It's gone forever. And so we worry that
sometimes in the in the garbage that we're throwing out
could be hidden nuggets, things that could reveal fascinating insights
into the universe. But you know, hey, we're throwing it
in the trash. Pressure. All right, well, thank you Hunter
from Buffalo for asking that question, and so we'll get
into our last question of today, which is about the
(31:21):
Big Bang and black holes. But first let's take a
quick break, al right, Dianiel. Our last question of the
day here, it comes from Charles who has a question
(31:42):
about the Big Bang. And it's a big question. It's
a big it's a hole of a question. It's a
whole big question. So here's what Charles wanted to Hey, guys,
so we know that black holes appear when a huge
amount of mass is compacted into a tiny area of space.
So my question is, if during the Big Bang all
(32:03):
the matter in the universe was gathered into a really
small area of space, why didn't the Big Bang become
a giant black hole? Boom wow? When an awesome question.
It takes me a second just to kind of run
my head around it. Then make your head go boom
or I guess what's the sound of a black hole
being made? It's not boom, is it? It's like, uh, well,
(32:26):
I guess I've never kind of heard the words big
bang and black hole in the same sentence, have you?
Is it? It's not normal. Yeah, it's a fascinating topic,
and you know, we can get into it. But there
are black holes that were made in the first moments
of the Big Bang, and they have this awesome, awesome
title primordial black holes, one of my favorite names in physics.
(32:47):
They have little tales like lizards. But I guess the
question from Charles is, you know, we know that black
holes form when you get enough mass and stuff kind
of compacted and crushed together into the right sort of
as and the small enough volume, and so the Big Bang.
At some point in the Big Bang, there was a
lot of stuff in a very small amount of space.
(33:09):
So why didn't the Big Bang not bang? Why did
it bang after all? Why didn't bang? Why why did
it bang so bigly? Why why didn't it just collapse
into a black hole and stay not big bang? Yeah? Well,
I'm glad it didn't because if it had, you know,
we wouldn't be here to ask this question, and we
wouldn't have this amazing, crazy puzzle of a universe to
try to unravel. And I think the first sort of
(33:31):
idea to unravel here is to work out, like, what
are the necessary ingredients for a black hole? How do
you make a black hole? What has to happen for
a black hole to form? Because then because then that
will tell us kind of how it's different from the
conditions of the Big Bang, exactly exactly right. And I
think a lot of people think, oh, all you need
for a black hole is just a lot of stuff.
If a lot of stuff and it's dense enough, bloom,
(33:52):
you get a black hole. And you painted black, right,
you painted black? And then you sing that awesome song
from the Stones. Right, people think you just need to
create enough density and will collapse into a black hole. Yeah,
and that's close to true. Right. It's true that you
need a lot of energy density in one spot. Right,
you need one location with a huge amount of stuff
in it, and that can curve space. That's that's how
(34:14):
it happens. But the other thing you need is you
need that to happen in flat space. Right. We talked
about how space is curved, right, how space is expanding.
Space is not just like the backdrop for It's not
just like emptiness and you're putting stuff into it and
filling it up. Space responds to matter, Space high responds
to other things as well, forces and fields, and so
(34:36):
it's dynamical. It changes, it can grow, it can squish,
you can do all sorts of stuff. The canonical picture
of a black hole we have is in non expanding space,
is in space that's not growing. And so it's true
that if you have non expanding space, just like you
know a flat universe, and you put a bunch of
matter into it, then yes, it will form a black hole.
It will create curved space in that region that I
(35:00):
cannot escape. I see you need like um, you know,
static space almost you need like space that's just sitting
there chill. Yes, yeah, and that's the solution that was discovered. Right.
Remember black holes were discovered theoretically before they were actually
seeing experimentally. It was an idea that came out of
looking at the equations and people were studying Einstein's at
the time fairly new equations for general relativity and thinking,
(35:23):
all right, what are the consequences for the universe. Let's
look at what would happen in this scenario that scenario,
And one scenario they found is in static space and
non expanding space. If you put enough stuff in there,
then you get this weird feature of black hole. And
then you know, they went out and they actually found
it in the universe. But the theoretical concept of a
black hole starts from static space, as you say, or
(35:45):
we know that spaces expanding now, but it's not expanding
in a crazy way, like you can still make a
black hole as long as the space itself is not
expanding too much. Yes, And so that's exactly the reason
why the Big Bang didn't just make a black hole
is that it was crazy expanding back then it's still expanding.
Now we have dark energy when they the universe is expanding,
and that expansion is even accelerating. But back in the
(36:08):
early days, like during inflation and the Big Bang, it
was crazy expansion. Space was stretching and creating new space
at an incredible rate. Yeah, and we don't understand you know,
what caused that and how it worked. We call it
inflation just to sort of describe the expansion that we
think was happening. But you need a lot more density
in the early days of the universe to make black holes.
(36:31):
Given that expansion, it's like you have another force to
contend with. We talked about on the Cosmological Constant podcast
recently how the Cosmological constant, this force is providing this
like repulsive gravity. It's like pushing things away. It's it's
expanding space. It's working against gravity. So you need enough
stuff to overcome that as well. But it is possible,
(36:51):
like if bad enough stuff, like I'm writing The Big
Bang and I put enough stuff together, I could have
formed a black hole. It's a fascinating question. And people
think about this and they think about, like, if you
had enough stuff, could you have collapsed the universe. You
have canceled out the black big band. Yeah, and we
can dig into that into in a moment. But you
need one more things that you needed to be not
totally smooth. Like, if you have enough stuff and it's
(37:13):
totally smooth, then where are these black holes going to form? Right?
How do you pick where the black holes are? The
other thing you need for a black hole is you
need a bunch of stuff in one spot. But if
everywhere in the universe has the same amount of stuff
in it, then all the gravity just cancels out. Really, yeah,
you can cancel a black hole. Well, it won't form
a black hole, right, You won't form a black hole
(37:36):
if the universe is filled perfectly smoothly with stuff. And
we think now that the beginning of the universe, the
universe was infinite. It's not like the Big Bang was
one little dense pocket of stuff. The whole universe tucked
into an atom. We think it was an incredible density,
but it was still infinite. The whole universe was filled
with an infinite amount of stuff, just very very dense.
(37:58):
So in that configuration, if it totally smooth and very
very dense, then where did these black holes form? It's
like you can't make a chocolate chip out of a
chocolate bark. Kind of I'm grasping for analogies here, but
is that kind of like it's it's hard to see
the black hole, or it's hard to like all that
matter that dance everywhere doesn't doesn't like forming into black holes. Yeah.
(38:22):
I think there's two different arguments you could use your
mind to understand it. One is, take one particle, right,
think about one particle in the early moments there. If
if the universe is filled with stuff and there's the
same amount of stuff on its left and it's right,
it's gonna be pulled in both directions equally, and so
those forces will cancel. And the same if you go
up or down or forward or backwards, and so all
(38:43):
those forces cancel. And the same argument applies for every
particle in the universe. Another way to think about it
is like symmetry, Like if black hole is gonna form,
it's got to form somewhere. And if every place in
the universe is the same, then how did those get chosen?
So there's no way to choose where they happen, So
they just can't, I guess, to form a black hole.
(39:04):
You need sort of need some space around you, not
just a lot of mass and chill space, but you
also need to not have a lot of stuff around
you otherwise, like the stuff that you have would have
condense and compressed. Yes, it's not just that you need density.
You need more density than the areas around you. Right,
If everything is dense, but it's equally dense, nothing gets
the form of a black hole. If everything is dense
(39:24):
and you have one hyper dense spot, then that could
collapse into a black hole. I can have a black hole.
No one can have a black hole, that's right. And
you know, we did have these little areas of inhomogeneity
that came from quantum fluctuations and were blown up by inflation.
And so people do wonder, like, even after inflation, why
wasn't there so much stuff that the universe immediately collapsed
(39:47):
wherever those little pockets, those little seeds of things that
that allowed structure in the universe to form, those little
areas that were slightly denser that came from the quantum
fluctuations that were expanded from inflation, Why didn't those just
immediately trigger black holes? All right? Why did they happen
to form enough gravity to pull together to make galaxies
and stars and planets and not just collapse into black holes.
(40:09):
And that we don't know the answer to. It's just
like we had enough stuff to make structure, but not
so much that we just collapsed immediately into black holes,
and we're sort of lucky. I guess that only works
if the universe is infinite. If the universe was finite,
the big band could have become a black hole. If
the universe was finite, then it's still very, very large.
It's at least larger than you know, the age of
(40:30):
the universe, times and speed of light and you factor
and all the inflation. So that's a huge amount of stuff.
That's too much stuff to instantly collapse into a black
hole just because the speed of light would take too
long to cross it near the edges. I suppose if
space is flat and matter ends, then you could get
collapsing black holes. But we're not living near the edge.
If there is one, because we can see isotropic universe
(40:52):
in every direction, there could be a black ditch kind
of surrounding the universe. It's finite there they're would be,
but it would have to be enough stuff after inflation
for those things to happen. All right, Well, then what
the answer is why didn't the Big Bang become a
giant black hole? Is that there was just too much
stuff and space. What this was expanding too fast? Yes,
(41:13):
space was expanding too fast, which makes it hard to
form black holes. And you need over densities of stuff,
not just density. You need over density. You have to
have more than your neighbors. You don't have to just
have a lot of stuff. Does that mean I can
sort of kill a black hole if I expand the
space it's in fast enough. That's something we don't understand.
We don't think so. We think once the black hole
is formed, it's impossible to like dark energy expandify it.
(41:37):
We talked about this on the podcast. Once you know,
like could you shoot dark energy into a black hole
and destroy it? We don't know what would happen because
we don't really understand this whole expansion of space thing.
We don't know how that interacts with the black hole
that's already made. Right, All right, Well, I think that
answer is a question for Charles. Thank you for asking
the question. And I think it's sort of interesting how
(41:57):
where people's curiosity is going with these questions. You know,
you know, I feel like these questions are extrapolating from
things that we've talked about or they've learned, and it's
these are like next level questions. Yeah, these are attempts
to fit the ideas together, which is exactly what you
should be doing. You want to understand the whole universe.
You don't want to just understand this piece and that piece.
You want to have one unified understanding of the universe,
(42:19):
and that requires you to take this idea you heard
here and ask why doesn't that apply in this other situation,
or how does that make sense given this other thing
I know? And that's how you build together a working
knowledge of the whole universe. So keep doing it and
keep asking us questions if it doesn't make sense to you.
So congrats to Meredith Hunter and Charles for stumping a physicist,
(42:40):
which gives us great stuff to talk about on the podcast.
So thanks very much. You send your prize, But you know,
I think that's against the social discas, that's right, So
if you have questions about the universe or things you'd
like us to talk about, please do send them to
us at Questions at Daniel and Jorge dot com you.
Hope you enjoyed that. See you next time, YEA. Thanks
(43:05):
for listening and remember that Daniel and Jorge Explain the
Universe is a production of I heart Radio. For more
podcast from my heart Radio, visit the i heart Radio app,
Apple Podcasts, or wherever you listen to your favorite shows.
Daniel, do we get a lot of interesting questions of
the podcast, you know, through email or Twitter? Oh, we
get the best questions. I'll be honest. It's my favorite
moment of the day when I see a new question
come in from the listener line. All right, cool, So
tell me how do you decide when to answer a question.
Do you reply to them on the email or do
you wait until we talk about it on the podcast. Well,
(00:28):
I feel like these listeners want to know the answers.
So if I know the answers, I write them right back.
And if you don't, then I gotta go off and
do a little bit of research. And that's how a
question ends up on the podcast. I see you think
I know the answer, that's right, I'll ask a real expert.
It's basically, it's just a big stalling tactic when you're stumped.
That's right. Listeners are very smart and if they ask
(00:51):
me a hard enough question, it will end up on
the podcast. Hi war handm cartoonists and the creator of
pH D Commons. Hi. I'm Daniel. I'm a particle physicist
(01:13):
and I've often been stumped by listener questions. Welcome to
our podcast, Daniel and Jorge Explain the Universe a production
of I Heart Radio in which we take you on
a mental tour of the universe, all the things that
science has figured out, and all the things that science
is still puzzling over, all the things we know and
all the things we want to know, which is basically everything,
and that's right. We take you to the limits of
(01:33):
the curiosity of scientists and also to the limits of
the curiosity of our listeners. People would like you who
are listening to this podcast, who have questions about the universe,
about the cosmos, about our planet, and about the things
that make up who we are. Because being curious, it's
just part of being human. Wondering how this whole thing works,
how this amazing and crazy universe came to be, how
(01:53):
it's put together, and what its ultimate fate will be.
That's just part of being human. And so we think
that wondering and curio pocity belongs to everybody, and we
want to bring you to the forefront of knowledge. And
often we talk about the kind of questions as scientists
are asking about the universe, but sometimes we talk about
your question and mac question, Daniel is I'm curious about
how we still have a podcast who gave a couple
(02:15):
of introverts a platform this big to talk about the
small thing that is to you. Well, it just cost
us a few bananas a week, so I think that's
the that's the reason. Well, bananas are hard to come
by these days, you never know. But yeah, welcome to
our podcasts and sometimes in this podcast we love to
answer listener questions. So if you have a question, you
can send it to us via questions at Daniel and
(02:35):
Joorhead dot com or through our Twitter account. In it
that's right, I'm pretty good at monitoring the Twitter page
and answering listeners questions. In fact, it's the way I
take a break from my day working on something hard.
I'm gonna go take a break and answer some fun
listener questions. Yea, and sometimes you pay questions to answer
on the error. And so today on the podcast, we'll
be tackling listener question number ten, particle stars and universe
(03:03):
size black holes. And these are some of my favorite
episodes because I love understanding what the listeners are thinking
about and what they are wondering about. The reason that
we do the person on the street interviews is it
because we want to take the pulse of current knowledge.
What are people understanding? What are they confused about? Because
we want to educate them right there. We want to
take them and unravel those points of confusion, help them
(03:25):
have that moment of clarity of understanding when things click
into place. And another way to do that is to
have the listeners ask us directly something that they are
wondering about. And when we get a question that I
think is especially clever or hard to answer immediately, but
I think other people will want to hear the answer to,
then yeah, we put it on the podcast. Yeah. Do
people get a reward if they stump you, Daniel? You
(03:47):
send them about cracker Jack Prize. Yeah, I'll send you
a list of people you need to send cracker Jack
prizes to put that on your to do list. It's
the permit scheme for the universe. They just get the
joy of knowing that they've asked a really good question.
And you know, we've got a lot of wonderful questions.
We get questions from five year olds, we get questions
from nine year olds, and all of them just reflect
(04:07):
this desire to understand, to not live in confusion, but
to have all the pieces of the universe fit into
place in their minds, and that's my goal too. That's
everybody's school. Yeah, and we get pretty good questions, and
especially the ones we're going to cover today, I thought
they were pretty cool. I was like, Wow, I don't
think I know the answer to these questions, which is
not saying a lot I know, but still, I've been
(04:27):
hanging out with you for a couple of years and
I feel like I don't really know the answer to
these questions. Well, you know, I feel like you're a
deputized physicist. I've heard you answered physics questions when I
haven't been around. I thought that's a solid answer. Wow, yeah, yeah, yeah, Wikipedia,
thank you no. On our live stream, Remember, I got
dumped off for five minutes and came back and you
(04:48):
had totally answered a bund of physics questions, and I thought,
maybe I'm not even needed around here anymore. I've, you know,
I've made myself obsolete by teaching you enough physics. I
think I can probably handle answering a question. I just
can't hand the follow up questions. I'm guessing it's probably
when you know you need to call them real physics.
But today we have some really great questions about how
(05:08):
new stars forming, the guy about the large Hadron collider detector,
and about basically everything and the Big Bang and the
fate of our universe? Did they include also the meaning
of life? How much of the universe can you roll
up into one question? I think our third question today
might take the case, well, you know, you get one shot,
you might as well roll it all up into one big,
(05:29):
fat question. All right, Well, let's get into it. Our
first question comes from Meredith, and Meredith has a question
about the night sky. Hi, Daniel and Jorge. My name
is Meredith, and I've been wondering if new stars are
always appearing in the night sky and how do we
know if they're newly formed stars or if they're so
far away that their light has only just reached us. Thanks, alright,
(05:50):
awesome question, Meredith. I guess? Or question is this? I
guess does the night sky change, like do we get
new stars forming and disappearing all the time or is
it pretty much set in the I guess lifespan of
a human. Yeah, it's a wonderful question because it reflects
on these differences between like human scales and human time
length and cosmological timeline I'm getting the sing as you're
(06:12):
gonna say, No, the night sky is not static. No,
it's only static on the short little blip of life
that we live. Right. The universe has been around for
much much longer than a human life or ten human lives,
or a thousand human lives or a million human lives.
And that means that if you watched it on like
time lapse, it would seem really active and chaotic. It's
(06:33):
like a frothing puddle. Right. We're living sort of like
in slow motion, where the universe and the galaxy seem
like frozen in time, but in reality they're not. Yeah,
And we have the ability to sort of look back
into time, right, and also the ability to kind of
project forward to sort of get a broader sense of
the history of the Like, imagine that you were something
that lived just a brief millisecond and you live that
(06:56):
entire lifespan, that tiny little mill second inside an exploding
grenade or something, or you know, a rock dropping into
a puddle of water. It wouldn't seem very chaotic to
you because on that millisecon, not that much happens. You know,
things don't move very far, don't change very much. And
so that's our viewpoint of the universe. We live this
little brief lifespan inside a vast, very slow moving explosion.
(07:21):
But if you watched it happened at a faster pace,
you could tell that there are things bouncing off each other,
there's new stars forming, there's all sorts of crazy stuff
happening on the universe time scale. I was gonna say
it's it's like hitting the fast forward bund, but nowadays
we don't have fast forward buns. We just have like
skip ten seconds funds. And that wouldn't be already Netflix
(07:42):
that want to be very satisfying, would it? If you
skip the intro of the universe, you missed most of
the exciting style. Well, what if we are just living
in the intro of the universe. This is just the
credits and the drama hasn't even really begun. Somebody's gonna
skip us. Don't skip us. No, I feel bad every
time I skip the intro. That because somebody spend time
making that you watch it at least once, you know,
if it's more than fifteen seconds, then then I skip
(08:04):
it every time. All right, Well, I guess the question
is does the Nights Guy change and specifically, do we
get new stars in the nice guy? Like, could you
could I be watching this guy one of these nights
when I'm out in the wild or camping and suddenly
like a new star which shine that wasn't there before
and nobody in human history had recorded it? Is that possible? Yeah,
it's a fascinating question, and I think to understand that
(08:25):
we have to think about, like how stars are made.
Let make me think about how often that happens, and
also what fraction of the Milky Way we can actually see,
and those pieces together will help us answer this question,
like what are the chances of that happening? Depends on
all these different factors. Yeah, exactly, And so we have
to remember that, like how are stars made. It's not
like somebody just goes along in the simulation the universe
(08:47):
and runs some subroutine that says make new star. Like,
it happens through a process and it starts when clouds
of gas collapse. Okay, so let's get into star formation then.
So stars, you're saying, form when the cloud of gas
out there in the universe crunched together. Yeah, and the
Milky Way surprisingly is filled with these clouds. Our galaxy
is a bunch of stars in its dark matter. But
(09:07):
there's also sort of the raw materials of stars just
floating around there, these vast clouds of gas. They're like
seventy hydrogen and each one has like millions and millions
as much mass as our sun. They're like, you know,
a hundred light years wide, and there's thousands of these
things just sort of floating around the Milky Way capable
of making stars. It's like the raw on form basic
(09:30):
material of stars just waiting to be you know, brought
together by gravity. Yeah, it's like your star pantry, right,
It's all the ingredients needed, but just not in the
right arrangement. Okay. And so then eventually these clouds kind
of collapse because of gravity, and then that's how stars
get for Yeah, And there's a few ways that can happen.
One is they just get big enough. You know, they
slowly accumulate enough stuff that eventually their heat and their
(09:53):
pressure can no longer keep them from collapsing. Right, Gravity
is always working to pull stuff together, but if something
is hot enough, you know that it won't collapse. Like,
why isn't our atmosphere just collapsing into little stars all
the time? Because it's got energy, right that overcomes that
gravitational pull, like it wants to expand kind of. Yeah,
it's velocity is too great for gravity from the other
(10:14):
part of the atmosphere to pull it together. But if
the gas gets heavy enough, right, there's enough mass and
it's cold enough, then it can collapse. The gravity will
take over and just collapse it. And so that that
happens a lot in the in our Milky Way galaxy,
or does it happen because I guess maybe what you're
saying is that most of the stars we see when
(10:35):
we look at it out into the night sky come
from our Milky Way, So we should focus just on
sort of how stars form in the Milky Way. Yeah,
that's right. When you look at in the night sky,
you're looking at the stars in the Milky Way, you're
looking through the Milky Way out into the rest of
the universe. And if you had a really good telescope,
then you could see other galaxies also. They would show
up looking mostly like stars, unless your telescope was super awesome,
(10:56):
and you could tell that they had different shapes. And
you know, it's only like a hundred years ago that
anybody understood that those little blobs were entire other galaxies.
But yeah, most of the stars that you can see
are actually just stars in the Milky Way. Okay, so
we have these clouds and they're making stars. But can
you see these clouds in the night sky or the
daytime sky or are these pretty sort of hidden from us? Well,
(11:17):
if you ever see the band of the Milky Way,
like sometimes on a really clear night when you're going camping,
you see a bunch of stars and then you see
sort of this milky way in the sky. Right, that's
an accumulation of stars, but also gas and dust. That's
where new stars would come from, and that's where new
stars come from. That's the plane of the galaxy. That's
the densest region of the galaxy that you're looking at.
(11:38):
And you know, this is one of these the Orion
nebula in the direction of Orion is of a light
years away. It's capable of making stars. And you know,
we don't quite understand the whole process of how this happens.
Sometimes it's just gravitational collapse. Sometimes these clouds could collide
and the points of friction provide the sort of the
impetus to make the cloud collapse. Sometimes we think it
(11:59):
might be like a super nova went off and that
energy sort of triggers the cloud to collapse. It's not
an inevitable thing for a star to form out of
a cloud. You gotta kind of trigger it. Yeah, if
the cloud gets big enough and dense enough, or if
something comes along and strikes it, Yeah, then it can.
Then it can happen. Okay, I guess then if you're
not looking at the milk away, then is it possible
(12:19):
that a new star will form kind of like out
of the blue in between the stars. And if you
look the other direction, if you're not looking in the
milky way, they know, like, there aren't these clouds to
make stars out between galaxies. So it's really just only
in our galaxy that we could see a new star
be born. There are other galaxies that make their own
new stars also, but it's really hard to see a
single star inside another galaxy. That's really pretty tricky. So
(12:41):
it only really sort of be in our galaxy. And
when these collapses happen, they don't just like make one star.
You're talking about a cloud that's capable of making lots
and lots and stars at once. And so when the
collapse happens, you get a bunch of stars twins or
much more than that. Yeah, exactly. I don't even know
what the Latin word for that would be, but you
could get thousands of stars forming basically at the same time. Wow,
(13:04):
I see their stars are made in batches. Yeah, stars
are made in batches, just like cupcakes. Right, You don't
make one cupcake at a time and then they go
off into the galaxy, or do they? You know, is
it possible to that a star gets made somewhere and
then moves in another place, or is it pretty much
all condensed and concentrated in the center of the Milky Way.
It could happen also two different parts of the Milky
Way wherever one of these clouds are. And after the
(13:27):
gas collapses and forms the star, it doesn't change the
overall gravitational trajectory of that mass. And so whatever the
center of mass of that material was doing, probably orbiting
the center of the galaxy is what it will continue
to be doing. So these guys will be bound together
in their fates. They will be near ish each other,
sort of in the vicinity, but they may end up
getting spread out later, but initially they'll be moving together,
(13:49):
all right, So then what sort of the rate or
like how many new stars get made this way per
per day or per year. It's hard to say like
per day because it's pretty stochastic, like for this to happen,
clouds have to collide or a supernob has to go
off for the cloud has to reach the right critical
density or something. So it's easier to talk about sort
of averages. And you just think, like, how long has
(14:11):
the Milky Way been around, Well, about thirteen billion years,
and how many stars are there? Right, and there's a
hundred billion stars, right, and so that means that roughly
about every forty seven days in the history of the
Milky Way, a star has been made. Now, it's not
like every forty seven days a new one turns on.
(14:31):
You know, you get a thousand made, and then you
might go years and years before another one is made.
Then you get another thousand. But on average it's every
forty seven days. It's like Los Angeles star is born
every forty seven days, and a sucker is born every day.
There's a lot more suckers than stars. Yeah, exactly. Okay,
So an average, the Milky Way makes like one star
(14:53):
every month and a half. Yeah, one star every month
and a half. That's its rate of production. And you know,
the Milky Way is a big place, so that's not
a whole lot of new stars. You know, one star here,
another star could be on the other side of the
Milky Way. It's like a hundred thousand light years away.
So it's not that many because we can't see all
of them, right, But I guess of thinking about the
ones that we could see, what would be the rate,
(15:13):
do you think? Yeah, I think people would be surprised
to understand that when you look up at the night sky,
you're seeing a very small fraction of the Milky Way
because most of the Milky Way, the stars are too
far away for you to see them. Like, your naked
eye is not good enough at capturing those photons from
those stars. The stars from the other side of the
Milky Way, they're shooting their light at us, and it's
getting here. But you know, you might get like one
(15:33):
photon per minute. And so if you're looking up at
the night sky with a naked eye, you're only actually
seeing a few thousand stars of the Milky Way. Of
the hundred billion stars in the Milky Way, you're not
seeing all the stars you could be seeing of the
Milky Way. That's right. If you had like two hubbles
for eyeballs, you would see a lot more stars. Right.
It'd be kind of awkward to like getting your car
(15:54):
or walk around, but you'd have a great view at night,
like if my eyes were bigger or I had like
super night vision. Know, I mean, like literally, if you
had two hubbles attached to your eyeballs, you're being literal.
Was being literal, I was fantasizing from like go up
into space, grabbing one of these peas cups and sticking
in your eyes. Imagine what you could see um. And
so essentially that defines like a sphere, you know, nearby
(16:18):
stuff that you could see. So for us to see
a star be born, you would have to be born
fairly close to the earth. And again it depends like
how bright it is. If it's brighter, it could be
born further away. If it's dimmer, and have to be
born closer. And so we could just do a simple
division again and say, well, there's a few thousand visible
stars the Milky Ways, billions and billions of years old.
(16:38):
Do the math, and you get that a new visible
star appears about every million years. Oh, I see. If
I were to look at the night sky, I would
have to on average wait a million and a half
years to see a new star. Yeah, exactly to see
a new star be born. So not likely, not likely,
although you could get lucky. You could watch for ten
(17:00):
minutes and see a hundred stars appear. Right. That could happen,
because you could get a cluster of stars born near
the earth. But yeah, I wouldn't bet on it. You
could win the lottery, it's possible, Yeah, you could. And
she also asked about how do we know if the
stars are newly formed or if the light is just
(17:20):
reaching us? Right, which is another great question. Yeah, like
if I see something from if I am looking at
the next guy and I see something turn on like blink,
how do we know it's a star that formed or
maybe a star that what the form a long time
ago and now I'm seeing it. What's the difference in
her question? Yeah, I think she's asking did the star
just form if it turns on, or did it form
a long time ago and we're just now seeing the light.
(17:42):
And the answer is always the second. It's always that
we're just now seeing the light. And it formed a
while ago. If it formed really close to the Earth,
we'd be in trouble, right, No need another star really
close to the earth. So that means it has to
have formed somewhere far away, which means it takes light
a while to get here. And and she also asks, like,
you know, how do we know? We can measure the
distance to these stars using various methods. We had a
(18:04):
whole podcast about it. We can like look at it
from telescopes from different parts of the Earth and see
it shift, sort of the way you can tell how
far away something is by changing your eyeballs by opening
one eyeball or just the other one. With houbble telescopes,
that would be awesome at telling how far away basketball is.
So we have ways to tell how farstening is away.
(18:24):
And then we can tell this light from this star
that has just arrived since this five million years away,
that means the star formed five million years ago. Okay,
So I guess that the lesson is if you are
seeing a newly formed star in real time, then you're
kind of in big trouble. That's right, because that means
you're we you shoet have war more sun screened. Yeah,
(18:44):
I'd say run, but there's nowhere to run dig maybe.
All right, well that I think that answer is may
this question, which is that new stars are appearing in
the night sky, the answer is yes, but they probably
don't happen that often, maybe every one and a half
million years. So we're sort of blessed and stuck with
the nights guy that we have right now. That's right,
(19:05):
but hey, you never know. I wish upon a star
and maybe you'll see one. All right, let's get into
our other questions. We have more questions here about the
large Hadron collider and what Daniel actually does as a job,
and about the Big Bang and black holes. But first
let's take a quick break. All right. We're answering listener
(19:36):
questions and our next question comes from Hunter from Buffalo, Wyoming,
and he answer a question about what exactly does Daniel
do at this job other than napping. Let's get into it, alright,
and drinking coffee somehow at the same time. I don't
know how you do it. You have the coffee, then
you have the nap. That's the key. Anyway, here's Hunter's question.
(19:57):
Hey you guys, my name is Hunter from Buffalo, A Wyoming,
And my question for you is, how does the detector
at CERN actually work? How does this massive device detect
these tiny, tiny particle interactions? And when they do shoot
particles together, how do they make them hit each other?
(20:17):
I mean, these particles are so small and they're going
in this massive chamber. You figure that there's a chance
that they miss each other. So how do they do it? Thanks?
All right, thank you, Hunter Daniel. I feel like Hunter
is kind of skeptical about your your professional year. He
doesn't seem like it should work. Are you sure that skepticism?
Maybe it's all Maybe it's wonder right. You see, he's amazed.
(20:42):
He's amazed that you have a job. I'm amazed that
I have a job doing this. Sometimes. I mean I
get to like tear apart matter and figure out what
it's made out of. As a job, I feel pretty
lucky and special sometimes awesome. And so his question is
how does the large hadron collider detector actually work? I
guess he's he's sort of wondering about the mechanics because
it seems like, we know, you guys smashed particles together.
(21:04):
But I guess this question is that it seems something
impossible to do, Like, how do you take a pin
and have it hit the head of another pin and
actually see what happened. Yeah, it's a great question, and
it's fascinating because he asked questions about the only two
parts that we can do, which is like, try to
smash stuff together and then look at the stuff that
comes out. We can't actually see the collision itself, right,
(21:27):
this moment of collision when something magical happens will not magical. Obviously,
something scientific happens and the new particle is made. That
moment is invisible to us. But we can try to
control the initial situation, what we're shooting in at what energy,
and then we can try to observe what comes out
the eventual stuff. So the first part is like how
do you shoot these things together and actually make them hit?
(21:49):
And you totally right, Hunter that if you shot one
proton at another proton, you would miss, I mean did again,
you would miss, and you'd miss like a hundred billion
times before maybe you would hit, So that it's not
what we do. Instead, what we do is we fill
our guns with a hundred billion protons and we shoot
it at a hundred billion protons, and we shoot those
little like clouds of protons at each other. I see.
(22:12):
It's kind of like dating. Do you get to do
a lot of swives before you find the right person? Yeah, exactly,
you gotta throw a lot of darts at the wall,
and so here, essentially we're throwing a cloud of darts
against another cloud of darts and hoping that the tips meet.
And you don't just throw a bunch of darts, you
throw like a bazillion darts a bazillion times a second. Yeah,
every twenty five nano seconds, one of these bunches bunches,
(22:36):
the technical term we use for this little cloud of
protons were very fancy. One bunch which contains you know,
a hundred billion protons passes through another bunch, and that's
every twenty five seconds. We do it twenty four hours
a day, three sixty five days a year. And do
you call these collections of protons bunches? Then I know
you're trend is. If you collect particles, that's another particle.
(22:58):
I'm feeling some schmid here now about our naming scheme.
You know, we call those bunches and we collide them,
and you know, it's really it's an amazing engineering achievement
to build this thing, to accelerate the particles to this energy,
to focus those beams to the smallest possible dot, to
maximize the number of collisions we get. And when you
pass a hundred billion protons through another hundred billion protons,
(23:21):
both going and nearly the speed of light, you don't
get a hundred billion collisions. You get like sometimes zero,
sometimes five, sometimes ten, sometimes twenty five collisions. So the
probability is pretty low. It's like five in ten to
the ten. It's very small. Yeah, and the probability gets
better the tighter you can make your beam or the
denser you can make that little cloud, the smaller the
area over which you're spreading those protons. But it's not
(23:44):
very high. And even when we get collisions, mostly those
collisions are pretty boring. It's proton bounces off of proton.
Nothing happens, protons going protons like Billard balls. They just deflect. Yeah,
they just deflect. That's like nine nine percent at the time.
What happens. Usually it's not very exciting. I guess one
proton repels another proton, so they just kind of like
(24:04):
push each other away. Yeah, they're both possitively charged and
they will interact. But that's the most likely thing to happen.
If you're throwing darts at a wall, you know, most
of the spots on that dartboard are proton bouncedself proton.
Sometimes you hit the spot where like it makes a
Higgs boson, or it makes some new weird particle. And
that's why we do it so often, because we're sifting
through so many collisions looking for the rare one that
(24:27):
will help us see something new. We think the weird
stuff is rare, so we have to look at a
lot of collisions to find them. Seems like sifting through
sand for a special grain of sand. Yeah. I think
that's probably a lot like tinder, right, just like you
were saying, it's a lot like data. Um, you're looking
for that one special somebody, and you've gotta look through
a lot of people sometimes to find the one that fits.
And so part of a hunter's question was, first of all,
(24:47):
how do you smash it together? I think you can
answer that, But now how do you tell what actually happened?
You know, because I imagine these are, you know, small
things that smashed together. How do you actually tell what
happened when they smashed together. Yeah, you can't just like
take a video. We'd love to do that, but first
of all, these things happened too fast. So for example,
a Higgs boson or a top cork, if you make it,
(25:08):
it lasts for ten to the minus twenty three seconds
before it turns into other particles, So you just can't
see it. Like, we don't have cameras that are that fast,
and on top of being super duper short lived, they're
super duper tiny, and we don't have cameras that can
see things that's small, and so they're smaller than the
wavelength of light we could use, so we don't see
(25:30):
at all these collisions. They're totally invisible to us. It's
like they happen behind a dark curtain. Instead, what we
see is that what they turned into is you know what,
trot's out onto the stage in front of the curtain. Hre.
It's more like showing up at an intersection after a
car crash and trying to figure out what happened because
we see the remnants, you see, like the bits and pieces. Yeah,
the Higgs or the top or whatever happened will turn
(25:52):
into other particles that do last long enough that we
can observe, and so we look at those we try
to figure out from what's left over, from what was produced,
what actually happened in that exciting moment of collision. And
that's kind of what you see when you look up
pictures of the large Hattern collider. They mostly show you detectors,
like the giant machines used to figure out what came
(26:12):
out of these collisions, like the huge cylinder and the
sort of warehouse size machines and the little tiny people
standing in front of it. That's that's kind of what
you see, right. It's it's the detectors, not the actual
like gun that shoots the proton. That's right. And in fact,
they're totally different communities of people that work on that.
Like I work at SIR and I work on the
l C. I don't work on the accelerator at all.
(26:33):
I have no expertise in building an accelerator. But I
work on a group of people that built the detector
that surrounds this collision point to take some kind of
digital picture of what flew out of it. And that's
what you're describing, these huge detectors. And so this, for example,
I'm in the Atlas collaboration, and there are four places
around the ring where people have built these detectors to
surround it. And so the Atlas Collaboration built the Atlas detector,
(26:57):
and a lot of the other detectors follow a similar scheme. Essentially,
what you're trying to do is take pictures of the
particles that fly out, but again you can't directly image them.
You have to measure somehow their properties. You have to
measure what they're doing. It. It's not just about capturing them.
It's like, oh, it was going this way with the speed,
with this momentum. That's exactly it. And so what we
do is we pass all the particles through a magnetic
(27:18):
field because by seeing how much they curve in that field,
we can measure their momentum and we can also tell
if they had an electric charge or not. And then
we have another layer of detectors that tries to measure
their energy. And so by putting these pieces of information together,
we can sort of tell what the particle was because
everything has a distinct signature, like an electron is a charge.
(27:38):
Particle will bend in that magnetic field and then it
will splash a bunch of its energy in that outer layer,
whereas a photon won't bend in that magnetic field would
be totally invisible, but then it will leave a splash
in the outer field. So we can sort of tell
what was what by piecing this together, but we never
we never get like a picture. It's like, oh, look,
this is the electron that was made. It's all like
we see tracks in the snow and we deduced from that,
(28:01):
you know what ran away. It's like your kid leaving
a mess. You're like, there was definitely a kid here.
There's a bucket of paint's built and I see little footprints,
so I'm pretty sure I know who's here. Delighted here,
and it's done instead of layers, right, Like, I think
that's cool that first you have the magnetic field and
that's how you measure momentum and charge, and then you
have a whole another layer that measures the energy, and
(28:23):
then another layer that measures other things. Yeah, because some
things escape, right, there's the layer that measures energy. It's
job is to slow the particle down to grab all
of its energy in order to measure it. But some
particles get right through there, like a muan will fly
right through. It hardly interacts with that detector, and so
we have a whole other layer of detectors on the
outside to try to bend muans and measure their energy.
(28:46):
So muans get bent twice, one in the inner magnetic
field and then one in the outer magnetic field, and
then some things escape completely, like neutrinos. If they're produced
in these collisions, they're just totally invisible to us. We
can't see them at all. Know, would fly through like
a light year of lead before interacted, So there's no
chance it would interact with our detector unless you put
a light year of lead. Yeah, I'm gonna write that
(29:08):
grand proposal, kind of get a cubic light year of lead, please,
that's right. Then you put it in your eyeballs and
you would be able to see Natrina even if the
n SF said, yes, tod that, Where would you even
source a cubic light year of lead? Like seriously? All right, well, um,
I think that's that kind of answers. The question is
how does the L A C detector actually work? It works,
(29:32):
and it works by amazing feats of engineering where you
take bazillions of protons and smashing bazillions of times a second,
and then using incredible and warehouse size machines. You kind
of track what happens and what comes out of these cours. Yeah,
and for every collision, we read out a hundred million
pieces of information and we do that every million, million,
(29:56):
hundred million. That's for one channel, and each channel can
have you know, bites and bite of data. And so
we have a lot of data coming out of this
thing because it's every twenty five nanoseconds, and so we're
just producing petabytes and petabytes of data and so actually
most of it we throw away. Most of it we
filter it away really quickly because usually it's boring right
to protons collide, to protons come out, that goes in
(30:17):
the trash. So a lot of the stuff that we
do is making rapid keep it or kill it decisions.
And that's kind of what you do, right that that's
kind of your part in this whole giant scientific endeavor
as you used to work on an algorithms that try
to sift through this data and throughout the ones that
we don't need. That's right. Part of being in a
collaboration of like five thousand people, becoming a specialist is
saying I'm gonna do this bit and you do that bit.
(30:38):
And the bit that I personally work on, that my
group works on is this trigger system that makes the
keep it or kill it decisions every twenty five nanoseconds.
And it's not just me it there's a collaboration of
hundreds of people who work on on that one system
in this huge detector filtering the car crash at the universe.
It's sort of terrifying sometimes because if you make the
wrong decisions, you're just throwing it away. Like once I did,
(31:00):
it's gone. It's gone forever. And so we worry that
sometimes in the in the garbage that we're throwing out
could be hidden nuggets, things that could reveal fascinating insights
into the universe. But you know, hey, we're throwing it
in the trash. Pressure. All right, well, thank you Hunter
from Buffalo for asking that question, and so we'll get
into our last question of today, which is about the
(31:21):
Big Bang and black holes. But first let's take a
quick break, al right, Dianiel. Our last question of the
day here, it comes from Charles who has a question
(31:42):
about the Big Bang. And it's a big question. It's
a big it's a hole of a question. It's a
whole big question. So here's what Charles wanted to Hey, guys,
so we know that black holes appear when a huge
amount of mass is compacted into a tiny area of space.
So my question is, if during the Big Bang all
(32:03):
the matter in the universe was gathered into a really
small area of space, why didn't the Big Bang become
a giant black hole? Boom wow? When an awesome question.
It takes me a second just to kind of run
my head around it. Then make your head go boom
or I guess what's the sound of a black hole
being made? It's not boom, is it? It's like, uh, well,
(32:26):
I guess I've never kind of heard the words big
bang and black hole in the same sentence, have you?
Is it? It's not normal. Yeah, it's a fascinating topic,
and you know, we can get into it. But there
are black holes that were made in the first moments
of the Big Bang, and they have this awesome, awesome
title primordial black holes, one of my favorite names in physics.
(32:47):
They have little tales like lizards. But I guess the
question from Charles is, you know, we know that black
holes form when you get enough mass and stuff kind
of compacted and crushed together into the right sort of
as and the small enough volume, and so the Big Bang.
At some point in the Big Bang, there was a
lot of stuff in a very small amount of space.
(33:09):
So why didn't the Big Bang not bang? Why did
it bang after all? Why didn't bang? Why why did
it bang so bigly? Why why didn't it just collapse
into a black hole and stay not big bang? Yeah? Well,
I'm glad it didn't because if it had, you know,
we wouldn't be here to ask this question, and we
wouldn't have this amazing, crazy puzzle of a universe to
try to unravel. And I think the first sort of
(33:31):
idea to unravel here is to work out, like, what
are the necessary ingredients for a black hole? How do
you make a black hole? What has to happen for
a black hole to form? Because then because then that
will tell us kind of how it's different from the
conditions of the Big Bang, exactly exactly right. And I
think a lot of people think, oh, all you need
for a black hole is just a lot of stuff.
If a lot of stuff and it's dense enough, bloom,
(33:52):
you get a black hole. And you painted black, right,
you painted black? And then you sing that awesome song
from the Stones. Right, people think you just need to
create enough density and will collapse into a black hole. Yeah,
and that's close to true. Right. It's true that you
need a lot of energy density in one spot. Right,
you need one location with a huge amount of stuff
in it, and that can curve space. That's that's how
(34:14):
it happens. But the other thing you need is you
need that to happen in flat space. Right. We talked
about how space is curved, right, how space is expanding.
Space is not just like the backdrop for It's not
just like emptiness and you're putting stuff into it and
filling it up. Space responds to matter, Space high responds
to other things as well, forces and fields, and so
(34:36):
it's dynamical. It changes, it can grow, it can squish,
you can do all sorts of stuff. The canonical picture
of a black hole we have is in non expanding space,
is in space that's not growing. And so it's true
that if you have non expanding space, just like you
know a flat universe, and you put a bunch of
matter into it, then yes, it will form a black hole.
It will create curved space in that region that I
(35:00):
cannot escape. I see you need like um, you know,
static space almost you need like space that's just sitting
there chill. Yes, yeah, and that's the solution that was discovered. Right.
Remember black holes were discovered theoretically before they were actually
seeing experimentally. It was an idea that came out of
looking at the equations and people were studying Einstein's at
the time fairly new equations for general relativity and thinking,
(35:23):
all right, what are the consequences for the universe. Let's
look at what would happen in this scenario that scenario,
And one scenario they found is in static space and
non expanding space. If you put enough stuff in there,
then you get this weird feature of black hole. And
then you know, they went out and they actually found
it in the universe. But the theoretical concept of a
black hole starts from static space, as you say, or
(35:45):
we know that spaces expanding now, but it's not expanding
in a crazy way, like you can still make a
black hole as long as the space itself is not
expanding too much. Yes, And so that's exactly the reason
why the Big Bang didn't just make a black hole
is that it was crazy expanding back then it's still expanding.
Now we have dark energy when they the universe is expanding,
and that expansion is even accelerating. But back in the
(36:08):
early days, like during inflation and the Big Bang, it
was crazy expansion. Space was stretching and creating new space
at an incredible rate. Yeah, and we don't understand you know,
what caused that and how it worked. We call it
inflation just to sort of describe the expansion that we
think was happening. But you need a lot more density
in the early days of the universe to make black holes.
(36:31):
Given that expansion, it's like you have another force to
contend with. We talked about on the Cosmological Constant podcast
recently how the Cosmological constant, this force is providing this
like repulsive gravity. It's like pushing things away. It's it's
expanding space. It's working against gravity. So you need enough
stuff to overcome that as well. But it is possible,
(36:51):
like if bad enough stuff, like I'm writing The Big
Bang and I put enough stuff together, I could have
formed a black hole. It's a fascinating question. And people
think about this and they think about, like, if you
had enough stuff, could you have collapsed the universe. You
have canceled out the black big band. Yeah, and we
can dig into that into in a moment. But you
need one more things that you needed to be not
totally smooth. Like, if you have enough stuff and it's
(37:13):
totally smooth, then where are these black holes going to form? Right?
How do you pick where the black holes are? The
other thing you need for a black hole is you
need a bunch of stuff in one spot. But if
everywhere in the universe has the same amount of stuff
in it, then all the gravity just cancels out. Really, yeah,
you can cancel a black hole. Well, it won't form
a black hole, right, You won't form a black hole
(37:36):
if the universe is filled perfectly smoothly with stuff. And
we think now that the beginning of the universe, the
universe was infinite. It's not like the Big Bang was
one little dense pocket of stuff. The whole universe tucked
into an atom. We think it was an incredible density,
but it was still infinite. The whole universe was filled
with an infinite amount of stuff, just very very dense.
(37:58):
So in that configuration, if it totally smooth and very
very dense, then where did these black holes form? It's
like you can't make a chocolate chip out of a
chocolate bark. Kind of I'm grasping for analogies here, but
is that kind of like it's it's hard to see
the black hole, or it's hard to like all that
matter that dance everywhere doesn't doesn't like forming into black holes. Yeah.
(38:22):
I think there's two different arguments you could use your
mind to understand it. One is, take one particle, right,
think about one particle in the early moments there. If
if the universe is filled with stuff and there's the
same amount of stuff on its left and it's right,
it's gonna be pulled in both directions equally, and so
those forces will cancel. And the same if you go
up or down or forward or backwards, and so all
(38:43):
those forces cancel. And the same argument applies for every
particle in the universe. Another way to think about it
is like symmetry, Like if black hole is gonna form,
it's got to form somewhere. And if every place in
the universe is the same, then how did those get chosen?
So there's no way to choose where they happen, So
they just can't, I guess, to form a black hole.
(39:04):
You need sort of need some space around you, not
just a lot of mass and chill space, but you
also need to not have a lot of stuff around
you otherwise, like the stuff that you have would have
condense and compressed. Yes, it's not just that you need density.
You need more density than the areas around you. Right,
If everything is dense, but it's equally dense, nothing gets
the form of a black hole. If everything is dense
(39:24):
and you have one hyper dense spot, then that could
collapse into a black hole. I can have a black hole.
No one can have a black hole, that's right. And
you know, we did have these little areas of inhomogeneity
that came from quantum fluctuations and were blown up by inflation.
And so people do wonder, like, even after inflation, why
wasn't there so much stuff that the universe immediately collapsed
(39:47):
wherever those little pockets, those little seeds of things that
that allowed structure in the universe to form, those little
areas that were slightly denser that came from the quantum
fluctuations that were expanded from inflation, Why didn't those just
immediately trigger black holes? All right? Why did they happen
to form enough gravity to pull together to make galaxies
and stars and planets and not just collapse into black holes.
(40:09):
And that we don't know the answer to. It's just
like we had enough stuff to make structure, but not
so much that we just collapsed immediately into black holes,
and we're sort of lucky. I guess that only works
if the universe is infinite. If the universe was finite,
the big band could have become a black hole. If
the universe was finite, then it's still very, very large.
It's at least larger than you know, the age of
(40:30):
the universe, times and speed of light and you factor
and all the inflation. So that's a huge amount of stuff.
That's too much stuff to instantly collapse into a black
hole just because the speed of light would take too
long to cross it near the edges. I suppose if
space is flat and matter ends, then you could get
collapsing black holes. But we're not living near the edge.
If there is one, because we can see isotropic universe
(40:52):
in every direction, there could be a black ditch kind
of surrounding the universe. It's finite there they're would be,
but it would have to be enough stuff after inflation
for those things to happen. All right, Well, then what
the answer is why didn't the Big Bang become a
giant black hole? Is that there was just too much
stuff and space. What this was expanding too fast? Yes,
(41:13):
space was expanding too fast, which makes it hard to
form black holes. And you need over densities of stuff,
not just density. You need over density. You have to
have more than your neighbors. You don't have to just
have a lot of stuff. Does that mean I can
sort of kill a black hole if I expand the
space it's in fast enough. That's something we don't understand.
We don't think so. We think once the black hole
is formed, it's impossible to like dark energy expandify it.
(41:37):
We talked about this on the podcast. Once you know,
like could you shoot dark energy into a black hole
and destroy it? We don't know what would happen because
we don't really understand this whole expansion of space thing.
We don't know how that interacts with the black hole
that's already made. Right, All right, Well, I think that
answer is a question for Charles. Thank you for asking
the question. And I think it's sort of interesting how
(41:57):
where people's curiosity is going with these questions. You know,
you know, I feel like these questions are extrapolating from
things that we've talked about or they've learned, and it's
these are like next level questions. Yeah, these are attempts
to fit the ideas together, which is exactly what you
should be doing. You want to understand the whole universe.
You don't want to just understand this piece and that piece.
You want to have one unified understanding of the universe,
(42:19):
and that requires you to take this idea you heard
here and ask why doesn't that apply in this other situation,
or how does that make sense given this other thing
I know? And that's how you build together a working
knowledge of the whole universe. So keep doing it and
keep asking us questions if it doesn't make sense to you.
So congrats to Meredith Hunter and Charles for stumping a physicist,
(42:40):
which gives us great stuff to talk about on the podcast.
So thanks very much. You send your prize, But you know,
I think that's against the social discas, that's right, So
if you have questions about the universe or things you'd
like us to talk about, please do send them to
us at Questions at Daniel and Jorge dot com you.
Hope you enjoyed that. See you next time, YEA. Thanks
(43:05):
for listening and remember that Daniel and Jorge Explain the
Universe is a production of I heart Radio. For more
podcast from my heart Radio, visit the i heart Radio app,
Apple Podcasts, or wherever you listen to your favorite shows.
Hosts And Creators
Daniel Whiteson
Kelly Weinersmith
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