What are white holes?

You've heard of black holes but what are white holes?

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Episode Transcript

Speaker 1 (00:08):
Hey, or I have a question for you about science
and naming things. You know, that's that's an issue with me, right, Daniel,
I've heard that before. Yes, what happened? Did they give
something a totally absurd name? Again? In physics? Well, I'm
sort of wondering about like the process, you know, like,
how do you feel about pre naming given a name

(00:29):
before it's born? Yeah, exactly, like what happens? Is it okay?
Or how do you feel about if we give something
a name before we discover it, like before we even
know if it exists. That way, you know, we don't
have to argue about it afterwards. Is it like reserving
a website name? Like you can just come up with
a name and if somebody discovers it, you own it. Yeah.

(00:52):
Or like one of our marital harmony strategies in my
in my marriage at least, is pre assignment of blame, Like, well,
if this happens, your fault, and we agree that so
we don't have to argue about it afterwards. And how's that?
How's that worked out? It's great, it's great, and you
know you just accept the blame and move on, all right,
It's always my fault. Physics as well. No, but sometimes

(01:16):
sometimes in physics, you know, um, people have an idea
for a thing. We don't even know if it's actually
a thing in our universe, but they give it a
name anyway. Alright, So from now on, I say, any
future particles discovered should be called the or the I
think I've created a monster, the Wren. Hi. I'm I'm

(01:54):
a cartoonist and the creator of PhD comics. Hi, I'm Daniel.
I'm a part of physicists and a cheese aficionado. What's
your favorite cheese, Daniel? Oh, these days, I'm into the
sheep's cheese. I've been traveling through Europe last few weeks
and enjoying a lot of really interesting, soft, creamy sheeps cheesus.
I don't know the names of any of them, Thom,

(02:14):
I just gobble them up and smile. Maybe you can
pre name them. That's right, They're called Daniel's favorite cheese.
One Daniel's favorite cheese too. Well, before we get too cheesy,
Welcome to our podcast, Daniel and Jorge Explain the Universe,
a production of My Heart Radio That's Right, in which
we zoom around the universe trying to find interesting, fascinating

(02:35):
black things, white things, dark things, light things, cheesy things,
creamy things, and tasty things to talk about to entertain
and educate you. And we are qualified to do this
because we are the authors of a book called We
Have No Idea, a Guide to the Unknown Universe. So
if you are interested in all of these topics, then
check that out. What exactly does that qualify us for

(02:56):
other than shilling our book on our podcast? Isn't that
the synonym for podcast or just a schiller? You know?
I heard somebody stay the other day. Every conversation is
a podcast if you just close your eyes, or every
podcast um is a conversation if you open your eyes,
that's right. But we do love to explore things about

(03:19):
the universe that we know and things about the universe
that we don't know, like some things that are out
there that we don't understand, some things that might be
out there and we don't even know if they do exist.
We love to delve into the unknown and try to
just chat about with you so that you understand as
much as theoretical physicists do or don't. That's right. We

(03:39):
like to explore things and nobody knows right to right,
and we like talk about why nobody knows anything about them.
That's right exactly. And you know, one of my favorite
things in physics is that there are multiple ways to
sort of create a new idea. Like one way, the
classic way is what you discover something new in the universe, like,
what's this weird thing? It's doesn't it isn't explained by

(04:02):
any law of physics, therefore we need a new law
of physics. Or this tells us is something else in
the universe we didn't understand. That's a classic way, right,
Like you're doing something else, like you're in a bathtub,
or you're playing around with radioactive materials, and eureka, do
not play with radioactive materials in the bathtub? How many
times do I have to tell you that? I think

(04:23):
you're thinking of a toaster? That's the know. No, there's
more than one thing that doesn't mix well with bathtubs. Okay,
it's not an exclusive. Isn't this how power plants work?
Just a giant bathtub and some radioactive material Yeah, first
you get a radioactive toaster. Okay, then um no, that's

(04:43):
the recipe for the beginning of a terrible superhero novel. No.
But one way is to stumble over something new, usually
when you're doing a science experiment, but but not always right.
The other way, though, is to think of something new,
say like, huh, you know, if there's you know, X,
y Z particles, why isn't there also a W particle? Right?

(05:03):
Or you know, I see this pattern, you know, the
particles go like one, two, three, five? Is there a particle?
It's lots of number four. And that's another fascinating way
to explore the universe because you're relying on our mathematical
patterns and our understanding that the universe seems to follow
these patterns, and and then following those patterns to find

(05:25):
something real and out there in the universe. It's like
the theory tells you there should be something there, and
so you go and you look for it. Yes, and
we've done this successfully. I mean, that's how the Higgs
boson was discovered. We almost certainly would not have found
the Higgs boson if we weren't looking for it, because
it's pretty subtle, it's pretty hard to spot. But we
suspect that it was there because of a theoretical pattern

(05:46):
that made much more sense if you had this one
extra little particle um and you know, we've done this
lots of times in physics and also in chemistry, and like,
look at the periodic table for years and years there
were holes in that table. You say, huh, how can
we have element number forty four and forty six? Where
is element forty five? So you go out, you look forward,
You're trying to make it right. There's lots of times

(06:08):
when the theory guides you suggests there's a gap here
where there might be something new and real out there
for you to discover, and a lot of times you
find it right, like that there was an element forty
five and there was a Higgs boson. Yeah, I don't
know about a lot of times, but non zero number
of times, right, I wish it was more times. Um,
Although you know, this is sort of the theoretical direction,

(06:29):
and I think it's fascinating and it tells us something
about how, you know, the theories in our minds are
intimately connected with the reality out there in the universe. Although,
because I'm an experimentalist, I really prefer the first way,
you know, finding something new and weird out there, just
jumping in a sort of metaphorical ship and sailing across
the metaphorical ocean of ignorance to find something new and

(06:50):
crazy that makes the theorists to rewrite their laws. Right,
that's my personal scientific fantasy. But today we're focusing on
the other. Yeah. So then you can win a metaphorical
or get a metaphorical PhD. That's right. Well, you know,
then I'll have metaphorical groupies, which are better than not groupies,
you know. Hey, and you get the metaphorical prize. Metaphorical
prize money comes with the medical for price. Yeah. Well,

(07:13):
today we are going to be talking about a topic
that kind of falls in that later a category, right,
like the one where we physicists have dreamed about it,
have thought about it, have imagined it, but we don't
really know if it exists or if it's out there. Yeah,
I don't even know if it falls into that category yet.
It's like threatening to fall into that category. It's like

(07:34):
you know, um, yeah, rolling down the cliff towards that category.
You know, it's sort of like in the super category
of that category. I even know if it really exists
yet as an idea, but it's a fun topic to
think about. Yeah. So it's a super fascinating topic and
it came to us through a question from a reader.
So today we'll be talking about white holes. What is

(08:00):
white hole? How can you have a hole that's white?
That's right, Um, that's the topic of today's podcast, and
we want to give a special shout out to one
of our listeners. You see, I alum Ryan Keith, whose
birthday is this week, and this shout out comes to
her from her sister, Kate Azar, who's also a u
c I alum, and the two of them told me

(08:20):
that they sometimes wish they were still on campus at
u c I so they could get accosted by a
random physicist asking them questions. But the only wish sets
sometimes most of the time they're happy they're not being
a cost by physics. Happy they don't want it often
enough to actually go to campus and hang out, you know,
or come knock on my door and offer to answer

(08:43):
these questions. It's not that hard, you know. My office
number is listed on the web, so anybody wants to
come by and answer questions is welcome to But nobody
ever does. I feel like that's when we know we'll
have we made it, Daniel, when people show up at
your office and they're like, hey, ask me a question. Yeah, well,
I'll let you know that ever happens. Well, this is

(09:03):
a perfect point to take a break. Well, so, white holes.
This is a pretty crazy topic because I think everyone
has heard of black holes, right exactly where most people

(09:27):
have heard of them, But how many people have heard
of white holes? Yeah? And black holes are definitely part
of the sort of culture, and people have heard about them,
and they're in movies and you know, probably in rap
songs and all sorts of stuff. They've deeply penetrated the
sort of social brain on physics. Um, And so I
was curious, like, what do people know about white holes?

(09:47):
Has anybody heard of them before? Does anybody understand it? Yes?
As usual, Daniel went out there and talked to people
in the street and asked them if they knew what
a white hole was. And so, before you listen to
these answers, think about it for a second. If you
were accosted by a physicist, or if you went into
Daniel's office and asked him to ask you a question
and he asked you what is a white hole? What

(10:10):
would you answer? You'd say, Oops, I regret doing this.
Here's what people had to say, And usually I would say,
no googling, But in this case, googling won't even help you. No,
I've never heard that. I've heard a black hole though, Okay,
And what's your best guess what a white hole might be? Then? Um,
if black hole is black and white hole is white,
I've not actually okay, you only guess is what it

(10:30):
might be. I mean, so, if a black hole is
a curvature of space time that light cannot escape from,
I imagine a white hole would be the inverse of that.
But like, like that's I can't even wrap my brain
around quite what that would mean. No, I heard a
black hole, not Honestly, all I think about is like

(10:52):
a black hole. When I think of white hole? Is
that I'm not my share? No, I like, yes, but
no white hole. Yeah, it's like the opposite of a
black hole. What does that mean? It's like the Big
Bang essentially. That's kind of the only example that we
have of it. I'm pretty sure I remember hearing about it.
I have no idea what it is. Maybe there's like

(11:13):
too much energy from stars. I don't know actually what
it might be, all right. Not not a lot of
familiarity with white holes, yeah, you know, and not a
lot of people have a solid idea of what a
white hole is, and you know, um, as you'll hear
later on in the podcast, that puts them in some
pretty good company. Well, I like the person who said, um,

(11:35):
if a black hole is black, then a white hole
is white. Boom's and you know what that person was
thinking on their feet and that, and they're not too
far off, you know, like that's basically the logic, right,
That's that's the whole concept of a white hole is like,
here's a thing, could we have the opposite thing? Right?

(11:58):
Because you know, hey, and physics, there are lots of opposites.
Particles have antiparticles, right, you know, um pass down plus
has minus. You know, um, not everything has an opposite,
like mass doesn't have negative mass, but there are a
lot of things that have opposites. The universe likes to
have symmetry, it seems, and so it's totally reasonable when

(12:19):
you discover something to look for the sort of the
opposite of the negative of it, the mirror reflection of it. Um. Well,
technically that that a listener um that present is correct, right,
It's it's like a black holes black and a white
hole is white. That's pretty much all you need to know. Yeah,
that's it, and that's our podcast for today, folks, Thanks
very much, thank you very much. Well, this is kind

(12:40):
of a crazy subject, and to be honest, I had
not heard about white holes at all until I think recently.
Maybe you brought it up or in one of our episodes,
I mean thirty minutes ago, I said, let's do a
podcast about them. When you sent me the notes for this, yeah,
that's when I heard about it. Um, but what is
it like a new idea? Is it something that's been

(13:00):
around for a while, or is it, you know, something
you just came up with. That's right, One of these days,
I'm gonna prank you by inventing a totally ridiculous, made
up idea and have you do a whole podcast about
In the end, I'll reveal that it's just some silly
thought of mine, um, thirty minutes and you're like, gotcha, Yeah,

(13:23):
it will be a totally valid podcast episode that we
will totally publish it. Now, that would be the control episode, right,
we'll see how interested and um and in depth can
Jorge go on a topic that's complete nonsense that we
are control episode to see about anyone's listening to these
or it's the Placebo podcast. Right, how much can you

(13:44):
think you understand about something that actually means nothing? Um No,
but it's not that old. I mean, the whole idea
of black holes itself is not that old. It's like,
you know, bad as old as general relativity, which is
just about a hundred years right now. The black holes
only discuss heard a few decades ago. Right, It's an
actual thing in the universe. And so the first of all,
black holes are a great example of the sort of

(14:07):
theoretical lead discovery, like, wow, the equations tell us this
could exist. Like we did a bunch of experiments, we
learned something about the universe. We wrote equations that described
what we learned, and then we explore those equations and
discovered in some weird corners those equations just describe something
strange we've never seen before. Let's see if that means

(14:27):
the equations are wrong or there that things the equations
are right, and that thing is actually out there. Right,
So that's the sort of history of black holes. It's
crazy to think that I'm older than our our confirmation
of black holes. Like, for part of my life, we
didn't have black holes. Existed. That's right. I might say
that it's a more important moment in the history of

(14:47):
physics discovery of black holes than the birth of birth.
That remains to be seen, Like we'll see what physics
relished to be TVD. It's tv D. That's right. Life,
your life and over it. So you've got time to
ratch that up. Um. White holes I think proposed originally
in the sixties. And you know, the the whole idea

(15:09):
is not too far from what from what that listener,
what that interviewee said, which is like, Okay, we have
this thing a black holes. Right. Black hole is a
region where things can enter but nothing can escape, right,
and that's why they seem black. That's the definition of
a black hole. It's like a the part of space
where there's so much gravity nothing can come out of it.

(15:29):
That's right. And the way I like to think about
it is not like the gravity is pulling so hard
that even photons can't climb up that mountain, but that
gravity is there's so much gravity there. The space is
bent in such a way that there's just no paths out.
You know, photons are zooming around inside the black hole,
but it's just space is bent in a way that
makes it sort of self contained. It's like cut off

(15:52):
from the rest of the universe, like a hole in
space literally, yeah, or sort of like you know, a
sub universe, right, Like there's just no way out of it.
You know, it's an escape room whether it just is
no key, Um, it doesn't matter how smart you are.
And so people thought, well, is it possible to the opposite, right,
and the opposite of a black hole, and you name
it a white hole? Right? Um, is a region where

(16:15):
nothing can enter, right, So things can escape, things can
shoot out of it, but nothing can go into it.
Like if you try to go into it, but what happened?
You get bounced back? Or yeah, well the way like
nothing can leave a black hole, right because the space
there is disconnected. You can't get into a white hole
like you'll you know, the paths that approach a white
hole get bent away from it rather than all getting

(16:36):
bent to it, they just get bent away from it.
Yeah okay, but you know, and that makes you wonder like, Okay,
when you invert a white a black hole, you get
a white hole. You like, inverted the word black into
the word white. Why don't you invert hole also? Right?
Like why isn't a black hole inverted into a I
don't know, like a white what's the opposite of a hole,
a bump? I don't know, a stump, white bump. And

(17:01):
that explains that why they don't use it. They can't
get any funding for white bumps. Yeah, exactly. And so
the next thing you can do is you can say, well,
is that possible? Like, you know, could that thing exist
at all? It is? Do the equations in fact predict
the existence of this kind of thing? Something where nothing, um,

(17:23):
nothing can enter, but things can escape, right, And just
like take a moment to think about like what that
would mean physically, Like here's something where nothing is allowed
to go in, but it's like shooting out particles all
the time, right, Like things can leave it. It's like,
you know it's what it has things inside, Yeah, but
it's um If it doesn't have things inside, it doesn't exist, right,

(17:44):
Like it only exists if it has some mass to it.
It's not just that things can leave, but is that
anything inside of it? It gets shot out kind of right,
Like it's if it's the over site of a black hole,
where like it gets sucked in and can't escape, then
is the is it that anything inside just automatically gets expelled. Yeah,
I think everything inside eventually gets kicked out. And so

(18:08):
you know what would that be like what would it
look like? You know, a white hole in that sense
would be like a bright source of you know, radiation
of particles and light and all sorts of stuff. And
so in that sense of white hole is like a
pretty good name for it. But you know it's like
a bright source, you know, so it looks it's very bright.
It's like white. Right, that's the idea of the name.
I think why the name makes some sense. But you know,

(18:31):
you can ask, like number one, is that consistent with
any of the theories that we have? Right? That was
just an idea, like, oh, here's a cool idea. Could
we have a rainbow hole? Could we have a purple hole? Right?
Could we have a white hole? And then you have
to ask, like, you know, one to the equation support
and two is it possible that actually exists out there
in the universe? Okay, So that's that's kind of the

(18:52):
short of it. Right. It's like imagine a black hole
and then just imagine the opposite of it. That's the
idea of a white hole. Right, I mean right, like
anything you imagine. I don't know about a black hole,
just trying not in said, but you know you have
to ask, like the opposite along what axis? Right, Like
what are you oppositing? You know, what are you inverting

(19:12):
to make a black hole into a white hole? Right?
Because you know you might not just everything. Yeah, what's
the opposite of chocolate? Is it peanut butter? Or is
it white chocolate or is it like you know, obviously
it's white chocolate. That's still chocolate, right. I think my
wife would disagree. I think she has strong opinions about

(19:33):
whether white chocolate should be called chocolate. If you tried
this rose chocolate, rose chocolate, I'm not making that up.
That's the thing that's really round chocolate, white chocolate. And
then in the history of chocolate science, they recently came
up with a new kind of chocolate, rose chocolate. Wow.
Was it a physicist who came up with that or
and I don't know if it was a chocolate As

(19:55):
well as our understanding of the universe, well, you know,
there is that famous correlation between the amount of chocolate
consumed per capita and the number of Nobel Prizes per capita.
So yeah, maybe it was. Um, I don't know, we
should do a whole podcast on rose chocolate, but maybe
we should actually eat some first. Wait wait, wait, hold
on a second, Actually I think that's not rose chocolate.

(20:16):
I think it's called ruby chocolate. Yeah, that's right, it's
ruby chocolate. All right, let's get into whether this even
makes any sense theoretically or practically, and let's get into
the whether or not these actually exists. But first let's
take a quick break. Alright, we're talking about white holes, Daniel,

(20:45):
and so you're saying it's like a black hole, but
it's kind of like where you almost the opposite of it.
If a black hole, um, doesn't let things escape, and
that's why it looks black. The white hole just pushes
everything out. That's why it looks white. Yeah, it look exactly.
And so I was trying to understand, like, what is
the white hole? How do you make one? What arrangement

(21:06):
of mass in space would give you a white hole?
Because like we understand how to make a black hole,
You take a bunch of stuff, you squeeze it down
to really small area, so you have so much gravity
that you get this crazy curvature space and nothing can leave. Right,
it's weird, it's crazy, it's real. But we understand how
you might do that. How do you build a white hole? Right?

(21:26):
What creates a white hole? What does it even mean?
Can I ask you a question? Um so, a lot
of times they explain black holes using the rubber sheet
analogy of the universe, you know, like where you imagine
that space is like a giant rubber sheet, and gravity
is kind of like the putting a bowling ball on
the rubber sheet and and seeing the indentation of it
on the sheet, right, And a lot of times they

(21:48):
explain black holes as least like if you put a
like a Brazilian bowling balls, it's just going to create
this giant hole DVID in the rubber sheet, right. Yeah.
Um so it's a white hole kind of the opposite
where you like, now you pinch a bit of that
rubber sheet and then you lift it up to create
like a like a peek instead of a hole. No,
And that's part of the really confusing bit is that

(22:10):
a white hole is also because that that would be
like negative gravity or having negative mass, but it's not
a white hole. A white hole is also just a
blob of mass, and it has a gravitational force towards
the white hole right, not away from it. This is
the really confusing part. A white hole is the same
arrangement of mass as a black hole, and it's sort

(22:32):
of only exists sort of encounterpart to the black hole. Like,
it's not clear that a white hole could ever exist
on its own. It might be sort of just like
a strange conceptual reflection of a black hole. Wait, you're
saying that if I, if I was in the presence
of a white hole, I would get attracted to it,
but I just couldn't enter it. Yeah, that's right, And

(22:52):
I think so there's one really crazy, weird conception of
a white hole. I think the simplest place to start
is actually to start with a word whole. Now, we
once talked in our podcast about like our wormholes real, right,
and it's possible the wormholes exist. Wormholes are allowed by
general relativity, and wormholes in some conception are essentially a

(23:13):
black hole, right where you can fall into the black hole,
except it's a wormhole. It's not just a you get
fall into the black hole and you're stuck there. Inside
the black hole is a connection to somewhere else in
the universe where you then get spout out. What's that
other side of the wormhole? Well, it's a white hole.
So you get sucked into the black hole and then

(23:33):
you get shot out the white hole, right, and that
and that sort of explains like how the black hole
in the white hole are really two halves of the
same thing. Right, A wormhole needs and and in and out.
That's right for it, you know, to be effective. Right,
you know, it's just a hole, that's right. And so
that's one conception of a white hole. It's like the

(23:55):
back end of a wormhole. Wait, do all black holes
night to a wormhole or only some of them or no,
we don't even know if they exist right now, most
of the black holes that we do know exist are
a different kind of black hole. They're the black kind
of black hole that's formed by gravitation collapse. Like if
a star and it's it's fusing, it doesn't want to
fuse anymore. It's used of aile, it's fuel, and now

(24:18):
it's collapsed into a really dense blob and it just creates,
you know, maybe a singularity we don't know what's going on,
but does not make a wormhole. But if wormholes do exist,
then one idea of them is a pair of holes,
the black hole in the white hole connected. But not
every black hole is a wormhole, Okay, all right, So
if a wormhole exists, one end would need to be

(24:40):
a black hole, in the other end would need to
be a white hole, right, And that's sort of how
you make sense of a black hole and a white
hole being formed from the same configuration of mass. Because
in order to bend space in that way, to bring
some distant part of space close so that you can
go from like here to Alpha Centauri without actually traveling
through all that space, takes a single configuration of mass.

(25:02):
How you do it, I don't know. Nobody knows. But
that's that's the reason why like a white hole in
a black hole or sort of a reflection of the
same arrangement of mass and energy that have, you know,
being configured to do this to create this wormhole thing.
And that's and that's the simplest sort of white hole
to understand. It gets crazier from there, it gets crazy.

(25:23):
There's there's multiple flavors of white holes. There's there's a
lot of different flavors of white hole and some of
them don't make any sense at all. Well, you were
telling me earlier that they don't make any sense to anybody, right,
Like these are these are a little bit far out
there and nobody really understands them. Yeah, you know, I
walked around campus and I went to some mathematicians offices

(25:44):
and some theoretical physicist offices and folks that like even
really think about the formal theory and um, and asked
them about white holes, like what do you know about
what holes? Do you have an idea? How would you
explain this? And um? They were stumped. Also, you know,
white holes are not something that most theoretical physicists thing
about it very much. They're not um a sort of
a topic of current research. They're not really taken very seriously.

(26:06):
It's sort of like it's not really a well formed
idea yet. It's like somebody said in one afternoon, like, oh,
maybe there's a white hole thing, and somebody else picked
it up and you know, walked a little further. But
it's not like finished yet. It's not like black holes,
where we had a really solid theoretical understanding of what
they would be like before we found them. This is
like maybe this might be a thing. Nobody's really even

(26:29):
thought it through all the way yet, So I asked
nobody sat down to do the math. It just kind
of gets mentioned. Yeah, and there's a few places where
people have worked it out, like this wormhole, black hole,
white the whole thing, and a couple of other cases
maybe we can talk about in a moment, But it's
not something that's really rigorously understood or or not something
that even people agree on what it means. You know,

(26:50):
you say white hole to one theorist, they might understand
something totally different than another theorist. So it's really just
it's sort of it's an idea of an idea so far. Alright,
So step us through how it works with these white
hole wormholes. So something goes into a black hole, it
goes through the wormhole, and it comes out the other end.
Does that kind of have what a white hole? Yeah,

(27:11):
and that's how a white hole would be spewing stuff out? Right,
What is it spewing out? Where is this stuff that
it spews outcome from? It comes from the black hole
on the other side, right, And that's why you know,
it doesn't necessarily have to have anything in it. Um
and you can still spew stuff out or conspuw stuff
out forever without disappearing, because whatever goes in the the
black hole on the other side comes out. But they're

(27:32):
in totally different parts of the universe, right, yes, but
sort of. I mean, remember we like to think of
space is sort of a flat sheet, right, It's like simple,
and you know, to go from here to there, you
need to go through space. But space can have all
sorts of different organizations, like it can be bent around
in a donut so that you know, you leave off

(27:53):
of one edge and you appear in the other edge,
And you can have all sorts of really complicated geometry
so that you can connect different parts of space. Things
that you would think are really far apart. You can
make it so you they're actually near each other, right,
and as you can, And that's what a wormhole is.
The way with the donut, have black chocolate frosting or
white chocolate. It depends on whether you're going into the

(28:15):
donut or out of the donut. Of course you're throwing
it up for you eating that, Um, I think it
tastes better going in there usually usually um. And And
that's sort of the simplest conception of the white hole
that I understand. But there are other ideas of white holes, right,
and these are not consistent necessarily with the whole wormhole concept.

(28:38):
They're just like different ideas of how a white hole
might appear. And one of them says. One of them
is that arguments sort of like this says that general
relativity is supposed to be time symmetric, meaning the equations
of general relativity work just as well for universe going
forwards in time and backwards in time, right, And that

(28:59):
might sound really weird to you. I think, how can
the universe go backwards and time? That doesn't make any sense. Well,
we don't know why how universe could go backwards, but
we also don't know why the universe is going forwards.
So it's sort of interesting to note that you could
run the universe backwards in general relativity and get the
same equations. Right, So a particle Earth going around the

(29:21):
Sun one way, the general relativity says it also works
the other way. Okay, So like if you hit reverse
right or the back arrow in the streaming video player,
it should look sort of normal, just backwards exactly. So
then you can say, well, there are weird things in
general relativity like black holes. So then what is the

(29:44):
time reversed black hole look like? Right, how can you
time reverse the black hole? IF's if general relativity is
supposed to be time reverse doble, and general relativity predicts
black holes, then what does the time reversed black hole
look like? Boom, that's a white hole. It looks like
something that's not sucking stuff in but just viewing stuff out. Yeah, exactly.

(30:07):
But general relativity is not the only law out there, right,
There are other laws like thermodynamics and the second law
of thermodynamics that says and grope always increases, and so
you know, you can't just create new matter, and you
can't just like violate the second law of thermodynamics by

(30:27):
like spewing that by undoing a black hole, right, And
so it's just it's sort of an unfinished concept because
while that would be allowed by general relativity, it's not
allowed by the second law of thermodynamics, And so we
don't really think that that's a thing. And so I
sort of get the sense that, um, this white hole
is sort of interesting to think about, but nobody can

(30:49):
really make it work or makes sense. Is that kind
of where we are with it? Yeah, exactly. It's like
open territory and theoretical physics that no, but he has
really gone and like chiseled out carefully to figure out
what's going on and is this interesting? And can we
even make a solid prediction experimentally of what to look for? Right?

(31:11):
But it's it's interesting because it's, uh, it seems like
there might be something there. Right, maybe in the future
somebody will think about it carefully enough to figure out
what ideas are important and how they fit together and
how to make it all connect, and then we'll know
what to look for. And you know that was the
case also for other theoretical things, like before Peter Higgs
came up with the Higgs boson, people knew that there

(31:33):
was there was something interesting to be done there, like
somebody had to figure out how these particles get masked.
Didn't quite make sense, and and you know, a young,
brash scientist waded into this muck and figured it out
and made it all clear, and then us experimentalist knew
what to look for. And that's sort of the stage
we're at with white holes. It's like we're pre prediscovery.

(31:53):
It's more of a like a fun maybe right now, Yeah, exactly.
You might say, like, um, well, are there is there
evidence of white holes? You know, like we look out there,
even if we don't have a solid theoryical understanding, can
we flip it on its head and say, let's just
look for them, because if we find one, then that
will give us a lot of clues as to how
the theory has to work. Right. And then also, what

(32:16):
would a white hole look like? Well, it'd be really
bright source of crazy radiation, and you know, the university
is filled with lots of crazy sources of radiation, and
so sometimes people like to speculate, like, oh, this big
gamma ray burst right, really a recent huge gamma ray burst,
people thought, could this be a white hole? And most
of the field went no, of course not, um it's

(32:39):
a supernova. But you know, it's fun to speculate. You're saying,
like maybe one of the stars we see at night
could be like a white hole, or it could be
except that we'd expect a white hole probably to be transient, right,
like it would um give off a huge amount of
radiation and then fizzle right, or or it could be
it could be not for bread it all, like if

(33:00):
it's the backside of a wormhole, then it only shows
up when something goes through it. Right, If nothing is
getting transited through the wormhole, then the white hole sort
of I don't know, dark for a while, yeah, exactly. Um,
And you know, other ideas are like, well, maybe the
Big Bang was a white hole, right, and does that

(33:21):
mean that our whole universe is the backside of a
black hole from somewhere else? You know, like because if
you're thinking about like crazy sources of radiation, spooky spewing
out of nowhere, that kind of sounds like the Big Bang.
Where Yeah, because the Big Bang, you get ask where
did all this stuff in the universe come from? Exactly?

(33:42):
Seems to sort of violate second law of the dynamics,
you know, if you think of the universe as a
closed system. So you know, and that's the sort of
fun stuff to think about it. I think when theoretical
physicists get tired of working on hard problems, they know, well,
they like to bounce this kind of stuff around in
their heads and see if they like find a new
little bite to take out of it. But you know,

(34:03):
it's not really something that it's like what a professional
dreamers dream about exactly when they're not dreaming professionally. Yeah, exactly.
When they're done eating the bananas and they smoke the peels,
what do these guys think about and what do they
do in their downtime? Yeah, and so I think if
you've got a bunch of theoretical physicists in a room

(34:25):
and you ask them all, or you get them all
in separate rooms, you ask them all to define a
white hole, I bet you would get as many different
answers as theorists you ask. It's just like white chocolate,
you know, if you ask people if they like white chocolate,
you would get a very polarizing All the people with
taste would say yes, and all the people who don't
understand chocolate would say no. I mean, it's pretty simple,

(34:50):
all right. So white hole sounds like they're a wait
for it, maybe kind of thing. Yeah, it's sort of
like there, like a weight hole. Yeah, either it's nothing
or it's like a little bit of twenty second century
physics that we're just hearing about for the first time now,
you know, because if you hear, if you read about
like the history of black holes, it's sort of existed

(35:12):
as a crazy idea for a long long time decades
before anybody took it seriously, and so maybe we're just
into those sort of early stages of the history of
white holes. In the future, textbooks be written about how
you know, people banded this idea around for a while
before X Y Z, physicists from you know, Ecuador or

(35:34):
somewhere cool um finally figured out what it meant and
then figured out how to look for it, and that's
when progress really started. It could be just in the
prehistory of the discovery of white holes, right, and hopefully
there'll be a little asterisks that says. Daniel and Jorge
made a podcast episode about it, which inspired that guy
person in Ecuador, that girl are for guy in Ecuador,

(35:57):
and there we go. Daniel and Jorge made a podcast
about it in which no progress was made, but other
people were inspired to actually make progress. Yes, that would
be a wonderful story. Well it it sounds like a
fun idea and I could potentially have big repercussions. I mean,
the Big Bank does turn out to be a white hole,
that would be a very big deal. Yeah, And you know,
if there are black holes and they're white holes, then

(36:18):
maybe there are roles holes out there in the universe.
You never know, or gray holes or grab a gray
warm holes, which is like a Game of Thrones reference
and a physics reference. That's right. That's right, So you know,
expand your mind and think about all the kind of
things that could be out there in the universe that
are out there in the universe, that are definitely not

(36:39):
out there in the universe, or that you know, might
eventually be in the minds of theorists and then discovered
by experimentalists. The universe is crazy, It's filled crazy stuff,
and one day we'll figure it all out. So go
out there and get crazy and enjoy some white chocolate.
See you next time. If you still have a question

(37:05):
after listening to all these explanations, please drop us a line.
We'd love to hear from you. You can find us
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(37:28):
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