May 29, 2025 • 43 mins
Daniel and Kelly answer questions about black holes, animal coloration, the big bang and time dilation.
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Episode Transcript
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Speaker 1 (00:06):
Black holes make a gravitational wave. White chocolate is Daniel's save.
Speaker 2 (00:11):
What controls colors on our furry friends? It's biology, so.
Speaker 1 (00:16):
It depends particle colliders make mini booms. The big Bang
filled the whole room.
Speaker 2 (00:22):
Biology, physics, archaeology, and forestry. Thank you for not asking
about chemistry.
Speaker 1 (00:28):
What diseases you get from your cats? We'll find answers
to all of that.
Speaker 2 (00:32):
Whatever questions keep you up at night, Daniel and Kelly's
answers will make it all right.
Speaker 1 (00:37):
Welcome to another Listener Questions episode on Daniel and Kelly's
Extraordinary Universe. Hello, I'm Kelly Wadersmith. I study parasites and space,
(01:00):
and I'm excited to learn more about black holes today.
Speaker 2 (01:02):
Hi. I'm Daniel. I'm a particle physicist and I love cats,
though I don't have nearly as many pets as exist
on the Wienersmith Farm.
Speaker 1 (01:10):
Well, I mean that's hard to beat. So you're a
cat person rather than a dog person, Is that what
I'm hearing?
Speaker 2 (01:15):
Well, I grew up with cats, always loved cats, but
my daughter is allergic cats. So now we have a
dog and love my dog of course, and so kind
of a dog person now but my daughter is getting
shots so that she can tolerate cats, and we're hoping
to get a cat soon.
Speaker 1 (01:30):
Oh exciting. Now are you going to adopt that cat?
Where are you going to get the cat from?
Speaker 2 (01:34):
It? Was that? Or create the cat in collisions at
the large hadron collider? So probably going to adopt it.
Speaker 1 (01:38):
Yeah, excellent. Well, we have a growing number of cats
because we live on a farm in the woods and
they find us and then they move in and I
can never kick them out. We almost ended up with
three beagles because they were also like dropped on the
property and well saying no more animals. I am like
simultaneously dumping pile of food in front of them. I
(02:01):
can't help myself.
Speaker 2 (02:02):
Oh I see that was the other option. The option
is adopt cats or have them adopt you, which is
what you're doing on the farm.
Speaker 1 (02:08):
Yep, yep, although the goats I think I will be
purchasing directly.
Speaker 2 (02:13):
Well, there's some sort of gravitational cat hole effect there,
I think, because the more cats you get, the more
they attract more cats, and then cats hear about your
farm they're like, oh wow, it's a cat haven, and
pretty soon you're gonna be a cat lady.
Speaker 1 (02:24):
Yeah, it's true. And we're also getting into chicken math.
Have you heard about chicken math?
Speaker 2 (02:29):
Tell me about chicken math.
Speaker 1 (02:31):
It's when you decide you're going to get four chickens
because it's not really that much work. So you actually
get ten chickens, and then before you know what, the
order you put in actually had a four in the front,
and now you've got forty chickens. And anyway, I did
duck math recently, and so now we have five ducks
and two geese coming. My husband's not excited about the geese.
We decided we were gonna name the geese Jacques Gusta
(02:55):
and franc Scene Gusto. I think Jacques had two wives.
One of them was Franccene. Anyway, we're very excited.
Speaker 2 (03:01):
Well, at least you have control over the names of
the pets, even if not the species or number of them.
Gives you a little bit of illusion of control.
Speaker 1 (03:09):
That's right. All that matters is that they let me
snuggle them.
Speaker 2 (03:12):
And in this crazy universe that can sometimes feel out
of our control, one way we can sort of establish
a little bit of a finger hold on sanity is
to think about the universe and try to understand it,
try to grapple with the mysteries of the cosmos, and
the best way to do that is to start by
asking questions. Questions we have and questions that you have.
Speaker 1 (03:32):
Chicken math might not make sense, but Daniel and Kelly's
answers do. So if you would like to submit your
questions about the universe, write us at questions at danielands
Kelly dot org. And it might take us a little
while before your answer airs, because we are actually fairly
well organized and we're about two months ahead of schedule,
and we've got a bit of a list of questions.
But you will get an answer from us, for sure.
(03:53):
We respond to everyone that's.
Speaker 2 (03:55):
Right right to us with your questions at questions at
Daniel and Kelly dot org. Everyone gets an answer, and
some people get on the podcast. And today we have
questions from three listeners about black holes, about furry pets,
and about tiny little bangs. Our first question comes from
Mark from Ireland about black holes. Here's Mark's question.
Speaker 3 (04:15):
Hi, Daniel and Kelly, this is Mark from Ireland and
I have a question about merging black holes. When two
black holes spiral towards each other to merge, they lose
mass and in doing so, generates gravitational waves. The newly
formed black hole will have a mass less than the
sum of the two original black holes. My question is
(04:39):
what actual mass is converted into gravitational waves and how
does this happen? In trying to get my head around
this phenomenon, I see there are lots of other interesting
questions that might arise. Maybe you can explain the merging
process and detail. I really enjoy the podcast and look
forward to new episodes. Thank you and keep up the
(05:02):
good work.
Speaker 1 (05:03):
Whoa great question. Okay, so I'm going to assume that
we've never actually seen black holes collide and we are
guessing what happens, or have we seen black.
Speaker 2 (05:11):
Holes Colyde, depends what you mean by seeing and black holes.
But yes, we actually have seen black holes collide. We've
observed these ingravitational waves collisions of dozens and dozens of
pairs of black holes. Now it seems sort of fantastical
and science fiction y, but it's our reality.
Speaker 1 (05:29):
Okay, So then what did you mean when you said
it depends what you mean by black holes and observe,
because it sounds like we have seen black holes collide.
Speaker 2 (05:38):
Yeah, I think most people in astronomy would say that
we have seen black holes collide. Okay, but you know,
we don't technically know that they are black holes. We've
seen very dense, compact, dark objects which are consistent with
black holes collide, that we've never really observed the event
horizon directly, So there's an asterisk there on do we
really know black holes are black holes? And in terms
(05:59):
of seeing, we've observed the radiation generated by that collision,
and that's what today's question is all about, how those
black holes merge and the radiation they give off. So
we've observed that gravitational radiation and it looks exactly like
you would expect from black holes colliding. But I don't
know if that counts as seeing it because it's not
like visible light.
Speaker 1 (06:17):
Okay, all right, I got it. So let's start from
the basics. What's a black hole?
Speaker 2 (06:22):
Right? So black hole famous prediction from classical general relativity. Right,
This is Einstein's theory that space is curved. Gravity is
not really a force. So what you think is gravity
is actually just the effect of space time being curved.
If you don't notice that space time is curved, it
looks like something is bending the light or changing the
path of the Earth. But it's actually just the curvature
(06:44):
of space time. Space time curves in response to mass,
and if you get enough mass in a small area,
it curves space time so much that things get trapped.
Space time is curved so that like light can't even escape.
It's not like there's so much gravity it even pulls
on photon. It's that space itself is bent so that
inside a black hole, space only points towards the center.
(07:06):
And so this creates the phenomenon we call the event horizon,
beyond which anything that falls in is trapped. It will
only move towards the center of the black hole. And
so this is the defining feature of a black hole,
the event horizon. This is the thing we haven't actually
literally technically observed. We've seen lots of indirect evidence for
black holes, but never actually observe the event horizon. And
(07:28):
beyond the event horizon, we can't tell anything that happens.
We can know the mass of the black hole, we
can know if it has electric charge, we can know
if it's spinning, but everything else is shrouded in mystery.
Speaker 1 (07:38):
We've done eleven of these listener questions episodes so far.
In thinking back, I feel like most of them have
had at least a question about a black hole. What
do you think it is about black holes that keep
people up at night?
Speaker 2 (07:51):
I think it's an incredible prediction of physics, something so
strange and beyond our intuition. But macroscopic, right, like quantum
mechanics makes all sorts of weirds about electrons, what they're
secretly doing while you're asleep, whatever, But we'll never see
those because they're microscopic. You can never observe them. Black
holes are a prediction that are like technically you could
see you could be near a black hole and observe
(08:12):
it and see all this strange effects. So it feels
sort of like magic, I think. And yeah, you're right,
people are fascinated by black holes. It's a significant fraction
of the questions that we get are about black holes.
So yeah, absolutely, it's fantastic. It's wonderful. It's incredible that
we've actually seen them, and we've seen these collisions. I
remember in the late nineties deciding where to go to
graduate school and what to work on, and I had
(08:33):
an opportunity to work on this project Lego the gravitational
wave observatory, and they were looking to see these black
holes merging and the gravitational waves generated by them. And
I remember thinking, they're never going to make that work.
It's crazy, and so I decided not to work on that.
And then of course they won the Nobel Prize. But
you know, hey, maybe if I had worked on it,
it wouldn't have worked out, and they wouldn't have won
(08:55):
a Nobel Prize. So maybe they won the Nobel Prize
because I didn't work on it.
Speaker 1 (09:00):
Anyway, hard to say, do you ever regret not going
into black holes? Or are you totally happy with the
path your life took?
Speaker 2 (09:07):
You know, there are always other options you could consider,
but I'm pretty happy with how everything worked out, and
so yeah, I don't worry too much about the counterfactuals.
But it is amazing that humanity has figured out a
way to observe these collisions. Einstein predicted this decades and
decades ago, but he thought it was going to be
impossible to observe because gravitational radiation is very, very weak,
because gravity itself is not very powerful, and so you
(09:29):
need an extraordinarily sensitive instrument to see this stretching and
squeezing of space time, this gravitational radiation, unless, of course,
you're right next to the black holes colliding, in which
case the signal is very powerful and you're probably dead.
Speaker 1 (09:43):
I feel like that's another thing that gets people interested
in the idea that observing this could kill you, but
if you could survive what's on the other side, I
just feel like it's amazing. But Okay, so we have
observed collisions, and you said that we've observed a lot
of them, and.
Speaker 2 (09:58):
It was a little bit of a surprise when we
saw the first one. You know, we didn't know how
often does this happen in the universe. We're building our
first eyeball for gravitational waves, and how long it takes
the sea one depends on how often they happen, and
there were lots of predictions. Some people predicted that it
would take decades to see one, but they saw one
almost immediately after turning the thing on, and everyone's like,
oh my gosh. Wow. So it turns out these collisions
(10:21):
happen more often than people suspected.
Speaker 1 (10:23):
So does that mean we were totally off in our
predictions for how many black holes there are or how
much they're moving? Around what were we wrong about in particular.
Speaker 2 (10:32):
So we're not sure. Black hole formation is still kind
of mystery. Super massive black holes or things we don't
really understand, so something we're still trying to understand and
we don't understand. Also the distribution of black hole masses.
There seem to be some smaller ones, some bigger ones,
but there aren't intermediate sized ones. So there's a lot
we don't understand about black hole formation, how often it happens,
how often they're close to each other, right, this kind
(10:54):
of stuff, So a lot of really interesting astrophysics is
being opened up by this study.
Speaker 1 (10:59):
No gold locks black holes, and Mark.
Speaker 2 (11:02):
Is interested in what happens when these two black holes
form and where the mass goes, because you know, there's
nothing free in the universe. If two black holes collide
and produce gravitational waves, gravitational waves carry energy. They're stretching
and squeezing of space time, and that energy has to
come from somewhere, and it comes from the internal energy
of the black hole system. These two things are orbiting
(11:24):
each other and for them to collapse down into one,
they have to lose that angular momentum, so they radiate
it away in gravitational waves and Marx's questions trying to
understand where the mass goes, because the mass of the
resulting black hole is not just the sum of the
masses of the two black holes that go in. It's
smaller than that because energy is lost to gravitational waves.
Speaker 1 (11:45):
And we have talked in other episodes about how energy
is mass, but maybe not. It's complicated, is that, right?
Speaker 2 (11:53):
Yeah, Mass is a measure of internal stored energy. Right,
So like a proton's mass, it's not just the mass
of the stuff that makes it up. It's the mass
of the stuff that makes it up, plus the energy
they have relative to each other. In fact, most of
the mass of the proton comes from that energy, the
binding energy of the quarks together. So if you have
a black hole black hole system, two black holes orbiting
(12:14):
each other, the mass of the whole system is the
massive black hole one plus the massive black hole two
plus their relative energy, and that's a lot. There's a
lot of gravitational energy between those two black holes. Let's
say black hole one is forty masses of the Sun,
for example, and black hole two is thirty masses of
the Sun. These are typical numbers. Then the energy of
(12:34):
the whole system would be forty plus thirty plus whatever
energy they have in their relative rotation, and that could
be like thirty or forty or fifty, right, it depends
on the configuration. So the total energy of the system
could be much more than seventy. You could be one hundred,
one hundred and twenty, this kind of thing. But a
lot of that energy is lost when the two radiated
away in order to combine. They have to radiate away
(12:57):
some energy in order to combine, otherwise they would just
or bit forever.
Speaker 1 (13:01):
And are they losing the energy of the black holes
or are they losing the energy that surrounds the black
holes or a little bit of both.
Speaker 2 (13:08):
Yeah, So this is a great question. And this is
what Mark is asking, is like he wants to do
some accounting. Is their mass actually lost? And I think
he's interested in this because people think of black holes
as something that can never lose mass, right at least
in classical general relativity, And so he's wondering, like, is
this a way for mass to escape somehow the black holes?
And it's a little bit tricky. There's a couple of
(13:28):
things to keep in mind. So the final black hole
is smaller than the sum of the two original black holes,
but always larger than either of them. So neither black
hole shrinks. Both black holes grow.
Speaker 1 (13:41):
Nope, no, no, no, You've lost me. Don't they become
one black hole when they merge.
Speaker 2 (13:46):
Yes, they become one black hole exactly, And so there's
no shrinking of the event horizon. Like the final event
horizon is bigger than either of the incoming event horizons. Okay,
so no event horizon is shrinking. It's not like you're
seeing behind the event horizon of either black hole. Both
of them are growing, right, but the final is smaller
than the sum of the two parts. It feels trickier.
(14:07):
It feels like I'm cheating.
Speaker 1 (14:09):
Yes, so I guess what I'm not following is Okay,
when they merge, I no longer think of them as
two separate parts. They're just one part. But it sounds
like you are still trying to keep accounting on two parts,
but now they've become one. So what am I missing?
Speaker 2 (14:24):
Yeah? I think think about it from the point of
view of black hole one. Okay, black Hole one has
an event horizon, and it has a certain mass, and
you could just be in its reference frame and it
has another black hole orbiting it, right, and then that
black hole radiates some energy and falls in and it
gets gobbled up. Black Hole one grows. Right, So we
followed all the rules of general relativity. The event horizon
(14:46):
is not shrunk because it can never shrink, because if
it did, you'd see things inside the event horizon. It
has grown. Its mass has gone up. Right, in classical
general relativity, black hole masses can only go up. So
from the point of view of black hole one, the
fact that black hole two is a black hole is
kind of irrelevant. It's eaten some energy and it's grown.
(15:06):
You can play the same game from the point of
view a black hole two. Right, The thing is symmetric.
Black Hole two grows, it gains mass, it's eating black
hole one. The two merge. The final result is bigger
than black hole two. Everything is happy from a general
relativity point of view.
Speaker 1 (15:21):
Okay, so at the end you still have just one
black hole, but that one black hole is bigger than
black hole one or black hole two were originally.
Speaker 2 (15:32):
Yes, exactly, Okay, and so it feels like mass has
been lost and we're playing some sort of shell game here.
I think there's another thing to understand that might help people,
which is, the mass of the black hole doesn't just
depend on what's beyond the event horizon. You can make
a black hole more massive without crossing the event horizon. So,
for example, say I shoot Kelly into orbit around a
(15:54):
black hole, hypothetically speaking, or Zach. Should we talk about Zaz? Yeah, yes,
of course Zach is in orbit around a black hole. Okay,
Now that black hole's mass grows even before Zach goes
over the event horizon. Right, you tend to think like, oh,
it's has to eat Zach before it grows to add
to its mass. But the mass is a measure of
(16:15):
the energy of the system, right, So the black hole's
mass actually grows before Zach falls over the event horizon.
Speaker 1 (16:23):
So at what point does Zach become part of the
system mm.
Speaker 2 (16:26):
Hmm, Well when he has a relationship to it, like
it's a gravitationally bound to it, than to an external
observer who's like a little bit further away, like it's
a black hole, Zach's system. The whole thing has more
mass than the black hole or than Zach does, and
so you don't have to like add stuff to the
black hole over the event horizon in order for the
(16:46):
black hole to gain in mass. This is actually crucial
for the way that black holes actually grow in the universe.
You might have heard, for example, if you do throw
your husband into a black hole, you'll never actually see
him cross the event horizon because time slows down. And
a lot of people write it and say, all right,
but then how do black holes actually grow if nothing
can cross the event horizon because time slows down. But
(17:07):
the answer is that the event horizon grows before Zack
reaches it. It grows out to meet him. He and
the event horizon approach each other. And so if Zach
was the last thing you ever threw into a black hole,
it's true that he would never cross it, you'd never
see him. But if after you throw Zach into a
black hole, you feel bad and you throw him a sandwich,
and that sandwich approaches the black hole, and as it
(17:29):
approaches the black hole, it pulls the event horizon over Zack, right,
because the event horizon comes out to meet the thing
that's approaching it. Because again, the mass of the black
hole depends on the stored energy, which includes the gravitational
energy it has with things around it. So you shouldn't
think of these things as just like boxes, right, Remember,
mass it's not just like a measure of how much
(17:49):
stuff is inside the black hole. It's a more comprehensive
measure of the energy of that whole system. You don't
have to be over the event horizon in order to
be part of that system.
Speaker 1 (18:00):
So one, the next time you say biology is complicated,
I'm going to just start laughing right away. But okay. Two,
So if you threw Zach ten thousand sandwiches because you
are like you're going to be there for a while,
would the event horizon pass Zach faster than if you
just threw him one sandwich because you don't really care
about what happens in the long run.
Speaker 2 (18:21):
Mm hmm, yeah, absolutely, okay. And if you threw them
in a series, then chicken sandwich number one would pass first,
chicken sandwich number two, then chicken number three, and the
last chicken sandwich would not cross the event horizon. So
it's true, you can't see something cross the event horizon
if it's the last thing that you throw. But in
our universe there's never a last thing. There's always like
(18:42):
more gas and more particles. And that's how black holes
in the universe actually grow, all right, But back to
Mark's question, what's going on here is that the mass
of the whole system. Right, Let's say we start with
our example of a forty and a thirty black hole,
and together they have a mass of like one hundred
and twenty, right, including all gravitational energy and rotational energy.
(19:02):
As they inspirle, they radiate away a bunch of that energy.
So the mass of the system was one twenty. It's
radiated away I don't know sixty. So now the final
black hole is sixty instead of one twenty. So sixty
is bigger than forty and bigger than thirty, but smaller
than forty plus thirty. But all that's happened is that
some of that rotational gravitational energy has been radiated away.
(19:25):
So even though the whole system started out with mass
of one twenty, now it's down to sixty because it's
radiated away half of its energy. I'm just making up
these numbers. They're roughly correct in the order of magnitude,
but I haven't done like any calculations. But that's the
right way to think about it as the energy of
the whole system.
Speaker 1 (19:41):
All right, Well, I think I understand black holes better now,
although I say that after every explanation and then I
get things wrong the next time we talk about it.
But let's see what Mark from Ireland thinks of that explanation.
Speaker 3 (19:55):
Hi, Daniel and Kelly, thank you very much for that
very informative answer to mike question. I think black holes
are really amazing, and merging black holes are even more amazing.
It's incredible that during the final fifth of a second
of their inward spiral, that they are flying around one
another at near relativistic speeds, often up to a rate
(20:17):
of two hundred and fifty orbits a second, and radiate
the equivalent of multiple solar masses of energy in the
former gravitational waves. It really is crazy, crazy physics. Well,
you've answered my questions very well, and thank you both
for taking the time to do so. I'm sure you'll
hear from me again at some stage in the future,
(20:38):
and in the meantime, I'm going to keep listening in.
Speaker 1 (20:57):
All right, So now we are onto by all, from
black holes to black spots. We are talking about patterns
on our furry friends. Let's hear what Simon from Germany
wanted to know about.
Speaker 4 (21:09):
Hi, Daniel N. Kelly Simon here from Germany. Thanks for
a great podcast. They're a fine background to my daily
run in the woods. I have a question here for Kelly,
one that has puzzled me for quite some time, and
it's in relation to the coloration of our furry friends.
So if we take a dog, for example, who is
(21:29):
black and white, and we zoom into the border between
the two colors, presumably we have one skin cell or
hair cell with black pigmentation and the neighboring cell as
a white pigmentation. The question is how is this information
passed down? Presumably the information is contained in a precursor cell,
(21:51):
one splitting into a black and one into a white.
The question is what is the mechanism for this? Thanks
for a great podcast, guys, Keep up the good work,
and I look forward to hearing some insight into this question.
Speaker 2 (22:03):
See biology also has really massively important questions.
Speaker 1 (22:07):
Are you being facetious?
Speaker 2 (22:08):
I can't tell no, I'm trying to make a gravitational pun.
Speaker 1 (22:12):
Oh good, excellent? Okay, sorry, went right over my head.
All right, So this was actually a fairly difficult question
to read about and to try to understand. And it's biology.
So it depends.
Speaker 2 (22:24):
Let me see if I can interpret the question to
make sure I understand what he's asking. Okay, I think
he's basically trying to do some physics here, which is
to like zoom in on the microprocesses involved. He's like
looking at his dog and seeing there's white patches and
black patches and wondering like what makes one bit white
and one black? And he's trying to understand it by
zooming in on the boundary and saying like, there's got
(22:44):
to be a point where there's one cell that's white
and one cell that's black, and that's where the difference is.
And he wants to highlight like what's going on between
those cells to understand why one turns white and black,
but also obviously to zoom out and understand, like how
do you get these patterns?
Speaker 1 (23:00):
Yes, And that's how I interpreted the question as well.
And the answer is that if you are looking at
animal patterns in general, it depends on the colors, it
depends on the pattern shape, it depends on the animal.
But Simon in particular referenced dogs and referenced white and black,
and so I decided that I was going to hone
(23:21):
in on that in particular, all right, because I needed
a foothold for this question. And so in dogs, there
are hair follicles or fur follicles that produce either black
or brown colors, or yellow or white colors. So one
follicle can produce either of those colors depending on the
instructions that it's given. So it's not like you have
(23:43):
different kinds of cells next to each other. It's all
the same cell, but it just is following different sets
of instructions.
Speaker 2 (23:51):
So they're just like printers, and they can get an
instruction for a black hair or a white hair and
they're happy to do it.
Speaker 1 (23:56):
That's right, Yes, exactly.
Speaker 2 (23:57):
Interesting, So who sends the instructions?
Speaker 1 (24:00):
So the instructions are encoded in a gene called a gooty,
and this gene is important for coloration in a lot
of different species, and the gene produces a hormone. The
hormone gets released from the cell.
Speaker 2 (24:15):
I'm a little confused because a gene is part of
your DNA, and so when you're saying the gene produces
a hormone, do you mean the gene when it's transcribed
into a protein is that hormone or the gene when
transcribed into a protein. Is some little machine that makes
the hormone or excuse my naive biologic question.
Speaker 1 (24:33):
No, No, that's a great question. I skipped a bunch
of steps. So, as I understand it, the gene encodes
for a hormone, and so when that gene is essentially
read and turned into a protein, that protein is a
hormone that subsequently gets released from the cell.
Speaker 2 (24:47):
The hair follicle cell, or some other kind of cell
that's controlling the hair follicle cells.
Speaker 1 (24:51):
What I think is happening here is that hair follicle
cells are producing this message and then also sharing it
with nearby cells.
Speaker 2 (24:57):
Oh interesting, Okay, one.
Speaker 1 (25:00):
Gets released and it talks to the nearby cells. If
you are a hair follicle next to a cell that
has just released this hormone, then you produce white.
Speaker 2 (25:11):
Interesting.
Speaker 1 (25:12):
If you don't get that hormone message, you default to
making black or brown?
Speaker 2 (25:18):
Wow? Fascinating right.
Speaker 1 (25:19):
So cells can do either, and so the question is
why are some cells making the signal that say turn
on white and why are some cells not making that
signal and telling nearby cells to default to brown or black?
Speaker 2 (25:35):
I loveI we like follow the chain of logic here like,
this is happening because of that, because of that, because
of that, because of that, and now we're like detectives
following the clues all the way back to the source.
So are you going to tell us who the killer is?
Who is making these decisions about whether to produce this hormone?
Speaker 1 (25:49):
You know, it's biology, so that the answer is never,
you know, kernel mustard. It's much more complicated. So you've
got this a gooty gene, And what determines whether or
not genes are turned on or off is that there
are these regions called promoters, and when something binds to
the promoter, that can turn the gene on. And so
it seems that whether or not this hormone is made
or not has to do with some complicated interactions happening
(26:11):
with the promoter for the genes. And so some cells
have these promoters turned on, so they're making this make
white message, and some genes don't get this promoter turned on,
so they are not giving a message, and nearby cells
make black or brown. Part of why I didn't get
into the details is because it might help you understand
exactly what's happening in this very particular instance. But to
(26:33):
understand coloration in general, that's more a story about promoters
getting turned on or off.
Speaker 2 (26:38):
So in general, then how do promoters get turned on
or off? I mean, this is part of your DNA,
what determines whether or not that DNA is getting turned
on or off.
Speaker 1 (26:48):
In general, we don't understand what's happening super well here,
and we understand this process a lot better in rodents
in birds, and in part that's because we feel much
more comfortable doing experiments on these animals in the lab.
Speaker 2 (27:00):
All that's kind of sad, I know.
Speaker 1 (27:02):
I know it is sad, But then you can also
pick animals that have much simpler color patterns and fewer
colors to boots, and that makes it easier to sort
of get a handle on these sorts of things, whereas
dogs have loads of different color patterns, and so trying
to get a handle on all of the different ways
these patterns can be made is much more complicated. The
manuscript that I read even had a sentence being like,
(27:23):
the situation in dogs is still unresolved, but they're doing
their best to figure it out.
Speaker 2 (27:27):
Well, this is super interesting how we can go from
like totally clues about it to understanding, Oh, follicles can
print either color to understanding what controls what they print,
and then follow that up the chain, and we're still
crawling up the chain. It's incredible.
Speaker 1 (27:40):
It is incredible, And like I said, we've got a
better handle on some species. And animal coloration in general
is sort of fascinating. Like sometimes there are some animals
that get it from their diet. For example, there are
some fish that have red coloration that they get from
the animals that they eat, and it just sort of
like accumulates in their skin.
Speaker 2 (27:57):
That would be amazing if humans, for example, change color
based on what they ate.
Speaker 1 (28:02):
Oh man, Yeah, there'd be very specific kinds of diets
I imagine, And around Halloween you'd eat like a lot
more carrots to get in the mood.
Speaker 2 (28:10):
Would be great, well, amazing. You could get a tan
just by having lunch.
Speaker 1 (28:16):
That would be incredible and probably a lot safer than
what we do now to get tans.
Speaker 2 (28:20):
All Right, So it turns out that Simon's question is
cracked open a huge canyon of unresolved questions in biology.
And not only do we not understand dogs, but the
whole question of how animals get color is still an
active area of research. And maybe having different answers in
each species. Amazing.
Speaker 1 (28:38):
That's right, And so let's see if Simon feels like
he learned anything from this answer.
Speaker 2 (28:44):
It sounds like Kelly read a lot of papers and
learned a lot.
Speaker 1 (28:46):
Kelly read a lot of papers, learned a lot, and
also learned that there's a lot that she doesn't know
about how this stuff works out. So it was a
learning experience for sure.
Speaker 2 (28:53):
All right, let's hear from Simon. Uh huh.
Speaker 4 (28:56):
Kelly definitely did learn something, and I think we as
the audience, I've definitely learned something too. Thanks Kelly for
the great insight into the invisible and incredibly complicated, it
seems biological mechanisms behind something as simple as the coloration
of our furry friends. I think understanding how it works
(29:16):
at this very last step perhaps gives us some insight
into how it works at the very first step. So
if I go back to the very first cell directly
after conceptions, say, where it splits into two, and then
to four, and then to eight and so on, eventually
giving rise to something that resembles a head, a torso,
and four legs, to understand the finer details of how
(29:37):
this information has passed down. How one cell knows to
be a torso while as a direct neighbor knows to
become a leg To understand how this transfer of information
works from one cell division to the next will be
fascinating to find out one day, But that's a question
for another day. Maybe. Thanks Kelly for taking the time
to look deeper into this mechanism and give us some
(29:59):
insight into this very last step of cell division. Gave
up the Great White cause.
Speaker 2 (30:21):
All right, we're back and we're moving on from the
mysteries of biology to the mysteries of the very early universe?
Which one do we understand less?
Speaker 1 (30:30):
Does it really need to be a competition? We don't
understand much about anything.
Speaker 2 (30:33):
Some days it feels like Leonardo wanted to understand the
relationship between particle collisions and the Big Bang. Here's his question.
Speaker 5 (30:41):
Hi, Kelly and Daniel loved the show. I heard particle
accelerators being described as tiny banks as in The Big
Bang but tiny in another podcast by doctor Katie Mack.
I also know we measure the energy of impacts in
giga electron votes, so can we also estimate the energy
of the Big Bang in electron votes?
Speaker 6 (31:00):
And?
Speaker 5 (31:01):
If so, why are we not classifying accelerators in Meli
or Fento banks and Easy because the number would be
too unsatisfying. Grains from Brazil.
Speaker 1 (31:10):
All right, So, Daniel, I remember you telling me once
that when you all turned on the particle collider for
the first time, there was a little bit of a
concern that maybe you would destroy the universe? Is that
because you all thought you were going to kick off
a tiny, big bang.
Speaker 2 (31:25):
Well, you know, anytime you do something that's never been
done before, you don't know what's going to happen. That's
the excitement of research, right, you know, you're exploring the unknown,
you're potentially unleashing something you didn't expect. And so yeah,
there's always a little frison of you know, enthusiasm and
fear when that happens.
Speaker 1 (31:44):
But when I first infect a fish with a parasite,
I don't worry that it's the end of humanity. Like,
the scale feels very different here.
Speaker 2 (31:51):
Maybe you should think bigger, Kelly. Yeah, okay, for those
of you worried at home, we didn't actually worry about
that too much because the collisions we'd do with the
particle colliders are not unusual in nature. They're very high
energy collisions from particles slamming into the Earth's atmosphere all
the time, much higher energy than what we achieve with
the large a drunk collider. We didn't worry that we'd
be collapsing the Higgs field or creating a black hole
(32:12):
or anything like that. But it is a fascinating experiment
because we are recreating conditions of the early universe. They're
also conditions of our current universe, just not as widespread.
And so it's often said that particle collisions recreate the
Big Bang, and that's true in some sense, but there's
also the potential there to sort of underscore misunderstandings about
(32:34):
the Big Bang that we should probably clear up.
Speaker 1 (32:36):
Well, can we start with, like, what is the defining
characteristic of a bang of any size? Small, medium, or large?
Speaker 2 (32:44):
Yeah, that's a good question. You know, in terms of
the Big Bang, the Big Bang is more of a
whiff than a bang, right, because the universe is expanding,
but it's really sort of cooling. It's becoming older and colder.
So the Big Bang is a description of how the
universe is decreasing in density as time goes on. It's
(33:05):
cooling down and getting more dilute. To run the clock backwards,
the universe gets hotter and denser, and we can run
backwards to a certain point what we call the plank
time beyond which we know our theories don't work, and
so everything is a question mark. And that's what we
call the Big Bang is expansion from that moment. So
it's a description of when the universe had very high
energy density. It's not a tiny dot in empty space.
(33:28):
The idea of a big bang, especially if you compare
to particle collisions, makes it sound like something happening at
one location, but the Big Bang was everywhere, and so
the similarity between particle collisions and the Big Bang is
that both have high energy density. Particle collisions of course,
though in just one spot, the Big Bang was everywhere.
Speaker 1 (33:46):
Got it? Okay? And what kind of scale difference are
we talking about in terms of energy between big and
tiny bangs?
Speaker 2 (33:53):
Yeah, so it's a pretty big difference. We compare these
things in a weird unit called electron volts, and it's
sort of a generic unit of energy. You can also
use it to measure mass, because we don't care about
things like the speed of light, and so an electron
volt is our unit, and to calibrate. For example, a
proton has a mass of one giga electron vault, so
a billion electron volts is the mass of a proton,
(34:16):
and collisions that we can achieve here on Earth are
in the scale of ten tarra electron vaults, so ten
thousand times the mass of a proton. And that sounds
pretty big, right, like ooh wow tarra Like that's a big.
Speaker 1 (34:30):
Number, But protons are pretty small.
Speaker 2 (34:32):
Protons are pretty small, exactly, And so the energy of
the Big Bang in the same units is ten to
the sixteen terra electron vaults, so ten to the fifteen
times more energy than the collisions we have at the LHC.
And ten of the fifteen is not a small number,
you know, it's not fifteen times. It's ten to fifteen
(34:53):
ten with fifteen zeros. If your bank account had one
with fifteen zeros in it, you'd be very very rich,
much much much richer than Elon Musk, probably like Elon
Musk squared. So it's very very high energy.
Speaker 1 (35:07):
If particle physicists had enough money, would you guys try
to make a particle collider you could do the Big
Bang in because I'm not sure we can trust.
Speaker 2 (35:17):
You, guys, No, I think we would. And you know,
the higher the energy collision, the more stuff you can make.
Right we don't know what's out there in the sort
of universe's menu of particles. And the incredible thing about
these collisions is that you pour energy in and there's
some sort of like quantum mechanical magic alchemy that happens,
and the universe decides what from its menu to make,
(35:38):
and it just sort of picks randomly from all the
things that it can make, which means that if you
pour enough energy into the collisions, you'll see everything the
universe is capable of making. If you do it often enough,
you don't even have to know what's out there. So
it's like a way to explore the capacity of the
universe without even knowing what it's capable of. You don't
have to leave your house. It's like, hey, make me
(36:00):
everything you can make right here. And as you turn
up that energy, you get to explore higher and higher
on nature's menu. And you could be just below the
threshold and not make the thing because they don't have
enough energy, and then you crank up the energy and
boom it starts to pop out. So Yeah, we'd love
to crank up the energy these things. We're still a
factor of ten to fifteen away from the Big Bang,
(36:21):
which means there could be particles that were made in
the early universe and they're super duper massive and we
haven't been able to make them yet. They could be
made in collisions of cosmic rays in the atmosphere, but
they're very short lived and we don't have detectors up
there to see them.
Speaker 1 (36:35):
So check out Daniels go fundme for the next big
particle collider.
Speaker 2 (36:40):
Leon artists question also asked, can we measure particle collisions
in terms of milli or fempto bangs? And the answer
is yes. So if you define one bang as ten
to the sixteen TeV, then the Large Hadron Collider has
collisions at about ten of the minus fifteen bangs or
one femto bang, which, yeah, doesn't sound very impressive and
not a great way to headline your science funding request.
Speaker 1 (37:03):
I don't know. I think femto bang sounds pretty.
Speaker 2 (37:05):
Cool, but it's also a way to sort of trace
back the history of the universe. Like as the energy
of your collisions goes up and up and up, you
recreate conditions that existed everywhere in the universe further and
further back in time and already ten TV one. Femto
bang is pretty high energy. It takes you all the
way back to like microseconds after the Big Bang because
(37:28):
the energy started to fall off really really quickly. It
becomes more gradual as time goes on. So we are
probing conditions in a very very early universe microseconds after
the Big Bang.
Speaker 1 (37:40):
Well, let's see if Leonardo is impressed by femto bangs.
Speaker 6 (37:45):
Hello, I'm also in teen Kelly, I'm also impressed by
fento bank. Also, thanks for clarifying the differences between a
particle collider and the early universe. I actually never considered
that there could have been particle so massive. If that
we will likely never be able to recreate. Thanks.
Speaker 2 (38:04):
All right, and today we have a special bonus question
on gravitational and velocity based time dilation from ASTHMT. We
decided we could squeeze in a fourth question for y'all,
So here's Ozma's question about time dilation.
Speaker 7 (38:19):
Hello, I'm a smith, and my question is what would
happen to time dialation if both high velocity and strong
magnetic feeling interacted simultaneously. Would this cost time to slow
down even more significantly or would there be no additional effect?
Thank you?
Speaker 1 (38:35):
All right? So Daniel, I have been listening, well you talk,
and I remember you told me there's two kinds of
time dilation, gravity and velocity. But my brain is a sieve,
so remind me what the difference between those is.
Speaker 2 (38:50):
Right, So there are two ways that clocks can appear slow. Now,
clocks that you hold, that you have with you always
run the same speed. But if Kelly gives Zach clock
and then shoots them out of a cannon a very
high speed relative to her, she will see Zach's clock
running slow because velocity time dilation says moving clocks run slow. Now, Zach,
(39:12):
with this telescope looking back at Kelly's clock, will disagree.
He'll say, no, no, Kelly's clock is running slow. So that
kind of time dilation is symmetric, meaning both wiener Smith's
see the other one's clock running slow. And at least
to this sort of confusion like whose clock is really
slower and the answer is there is no really slower,
they can argue forever and both be right. So it's
(39:33):
sort of a marital trap for the two of them.
Speaker 1 (39:35):
Yeah, that's not great.
Speaker 2 (39:37):
But the other kind of time dilation, gravitational time dilation,
is asymmetric, which means everybody can agree on it. So,
for example, if Kelly does drop Zach near a black hole,
she'll see his clock running slower, but he will see
her clock running faster. They agree in this scenario, but
whose clock is running slower or faster? Both of them
(39:58):
see their own clocks running at normal speed. And so
the cool thing here, and this is Ozma's question, is like,
what happens when you have both? Do they constructively interfered,
destructively interfered to his universe? Explode? What happens?
Speaker 1 (40:10):
I hope The answer is Kelly is right. Whatever time
Kelly says is the correct time.
Speaker 2 (40:18):
The answer is they both contribute. So let's say, for example,
that Kelly launches Zach into orbit. Right now, Zach is
going really, really fast, and so his velocity means that
his clock runs slower than clocks we have here on
Earth from our point of view. Okay, but he's also
further from the gravitational well of the Earth, so his
(40:41):
clocks will run faster than ours. Because of the gravitational
time dilation is less so we have actually gravitational time
dilation right here on the surface of the Earth. Because
of the Earth, we're all experiencing it all the time.
Clocks out in deep space run faster. So from Kelly's
point of view, Zach's clock runs slower because of velocity
and faster because of gravity, and the gravity actually wins out.
(41:05):
So the velocity time delation is like seven microseconds per
day if he's up with GPS satellites, and forty five
microseconds per day the other direction due to gravity. So
overall gravity wins.
Speaker 1 (41:19):
So when I shoot him into orbit, because gravity is
winning and it makes things faster, he should still be
on time or early to the meetings. I let no
excuse for being late, Is that right?
Speaker 2 (41:30):
I really feel like I don't want to get in
the middle of here. Physics is not going to solve
your marital.
Speaker 1 (41:35):
Problems, all right, all right, but baby sandwiches, well.
Speaker 2 (41:40):
Sandwiches yet well exactly now, from Zach's point of view,
both of the effects make Earth's clocks slower. It's fascinating
because from the Earth's point of view, we see the
effects having different directions. But from Zach's point of view,
he sees both effects having the same direction. He sees
us moving quickly, which means our clocks run slow, and
he sees a closer to a gravitational well of the earth,
(42:03):
which means our clocks run slow.
Speaker 1 (42:05):
Oh see, now, I feel like you're citing with zech.
This is no excuse.
Speaker 2 (42:11):
I feel like I need my lawyer present.
Speaker 1 (42:15):
All right, everybody, thanks for playing. Just a reminder that
you too can send us questions at questions at danielant
Kelly dot org. We answer every question, some of them
end up on the show and we can't wait to
hear from you.
Speaker 2 (42:26):
And some of our questions come from conversations on the discord.
We encourage you to join our discord, where people ask
and answer questions and make a bunch of nerdy jokes.
You can find the invitation on our website Daniel and
Kelly dot org.
Speaker 1 (42:45):
Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We
would love to hear from you, We really would.
Speaker 2 (42:52):
We want to know what questions you have about this
Extraordinary Universe.
Speaker 1 (42:56):
We want to know your thoughts on recent shows, suggestions
for future shows. If you contact us, we will get
back to you.
Speaker 2 (43:03):
We really mean it. We answer every message, email us
at Questions at Danielankelly dot.
Speaker 1 (43:09):
Org, or you can find us on social media. We
have accounts on x, Instagram, Blue Sky and on all
of those platforms. You can find us at D and
K Universe.
Speaker 2 (43:19):
Oh be shy right to us
Black holes make a gravitational wave. White chocolate is Daniel's save.
Speaker 2 (00:11):
What controls colors on our furry friends? It's biology, so.
Speaker 1 (00:16):
It depends particle colliders make mini booms. The big Bang
filled the whole room.
Speaker 2 (00:22):
Biology, physics, archaeology, and forestry. Thank you for not asking
about chemistry.
Speaker 1 (00:28):
What diseases you get from your cats? We'll find answers
to all of that.
Speaker 2 (00:32):
Whatever questions keep you up at night, Daniel and Kelly's
answers will make it all right.
Speaker 1 (00:37):
Welcome to another Listener Questions episode on Daniel and Kelly's
Extraordinary Universe. Hello, I'm Kelly Wadersmith. I study parasites and space,
(01:00):
and I'm excited to learn more about black holes today.
Speaker 2 (01:02):
Hi. I'm Daniel. I'm a particle physicist and I love cats,
though I don't have nearly as many pets as exist
on the Wienersmith Farm.
Speaker 1 (01:10):
Well, I mean that's hard to beat. So you're a
cat person rather than a dog person, Is that what
I'm hearing?
Speaker 2 (01:15):
Well, I grew up with cats, always loved cats, but
my daughter is allergic cats. So now we have a
dog and love my dog of course, and so kind
of a dog person now but my daughter is getting
shots so that she can tolerate cats, and we're hoping
to get a cat soon.
Speaker 1 (01:30):
Oh exciting. Now are you going to adopt that cat?
Where are you going to get the cat from?
Speaker 2 (01:34):
It? Was that? Or create the cat in collisions at
the large hadron collider? So probably going to adopt it.
Speaker 1 (01:38):
Yeah, excellent. Well, we have a growing number of cats
because we live on a farm in the woods and
they find us and then they move in and I
can never kick them out. We almost ended up with
three beagles because they were also like dropped on the
property and well saying no more animals. I am like
simultaneously dumping pile of food in front of them. I
(02:01):
can't help myself.
Speaker 2 (02:02):
Oh I see that was the other option. The option
is adopt cats or have them adopt you, which is
what you're doing on the farm.
Speaker 1 (02:08):
Yep, yep, although the goats I think I will be
purchasing directly.
Speaker 2 (02:13):
Well, there's some sort of gravitational cat hole effect there,
I think, because the more cats you get, the more
they attract more cats, and then cats hear about your
farm they're like, oh wow, it's a cat haven, and
pretty soon you're gonna be a cat lady.
Speaker 1 (02:24):
Yeah, it's true. And we're also getting into chicken math.
Have you heard about chicken math?
Speaker 2 (02:29):
Tell me about chicken math.
Speaker 1 (02:31):
It's when you decide you're going to get four chickens
because it's not really that much work. So you actually
get ten chickens, and then before you know what, the
order you put in actually had a four in the front,
and now you've got forty chickens. And anyway, I did
duck math recently, and so now we have five ducks
and two geese coming. My husband's not excited about the geese.
We decided we were gonna name the geese Jacques Gusta
(02:55):
and franc Scene Gusto. I think Jacques had two wives.
One of them was Franccene. Anyway, we're very excited.
Speaker 2 (03:01):
Well, at least you have control over the names of
the pets, even if not the species or number of them.
Gives you a little bit of illusion of control.
Speaker 1 (03:09):
That's right. All that matters is that they let me
snuggle them.
Speaker 2 (03:12):
And in this crazy universe that can sometimes feel out
of our control, one way we can sort of establish
a little bit of a finger hold on sanity is
to think about the universe and try to understand it,
try to grapple with the mysteries of the cosmos, and
the best way to do that is to start by
asking questions. Questions we have and questions that you have.
Speaker 1 (03:32):
Chicken math might not make sense, but Daniel and Kelly's
answers do. So if you would like to submit your
questions about the universe, write us at questions at danielands
Kelly dot org. And it might take us a little
while before your answer airs, because we are actually fairly
well organized and we're about two months ahead of schedule,
and we've got a bit of a list of questions.
But you will get an answer from us, for sure.
(03:53):
We respond to everyone that's.
Speaker 2 (03:55):
Right right to us with your questions at questions at
Daniel and Kelly dot org. Everyone gets an answer, and
some people get on the podcast. And today we have
questions from three listeners about black holes, about furry pets,
and about tiny little bangs. Our first question comes from
Mark from Ireland about black holes. Here's Mark's question.
Speaker 3 (04:15):
Hi, Daniel and Kelly, this is Mark from Ireland and
I have a question about merging black holes. When two
black holes spiral towards each other to merge, they lose
mass and in doing so, generates gravitational waves. The newly
formed black hole will have a mass less than the
sum of the two original black holes. My question is
(04:39):
what actual mass is converted into gravitational waves and how
does this happen? In trying to get my head around
this phenomenon, I see there are lots of other interesting
questions that might arise. Maybe you can explain the merging
process and detail. I really enjoy the podcast and look
forward to new episodes. Thank you and keep up the
(05:02):
good work.
Speaker 1 (05:03):
Whoa great question. Okay, so I'm going to assume that
we've never actually seen black holes collide and we are
guessing what happens, or have we seen black.
Speaker 2 (05:11):
Holes Colyde, depends what you mean by seeing and black holes.
But yes, we actually have seen black holes collide. We've
observed these ingravitational waves collisions of dozens and dozens of
pairs of black holes. Now it seems sort of fantastical
and science fiction y, but it's our reality.
Speaker 1 (05:29):
Okay, So then what did you mean when you said
it depends what you mean by black holes and observe,
because it sounds like we have seen black holes collide.
Speaker 2 (05:38):
Yeah, I think most people in astronomy would say that
we have seen black holes collide. Okay, but you know,
we don't technically know that they are black holes. We've
seen very dense, compact, dark objects which are consistent with
black holes collide, that we've never really observed the event
horizon directly, So there's an asterisk there on do we
really know black holes are black holes? And in terms
(05:59):
of seeing, we've observed the radiation generated by that collision,
and that's what today's question is all about, how those
black holes merge and the radiation they give off. So
we've observed that gravitational radiation and it looks exactly like
you would expect from black holes colliding. But I don't
know if that counts as seeing it because it's not
like visible light.
Speaker 1 (06:17):
Okay, all right, I got it. So let's start from
the basics. What's a black hole?
Speaker 2 (06:22):
Right? So black hole famous prediction from classical general relativity. Right,
This is Einstein's theory that space is curved. Gravity is
not really a force. So what you think is gravity
is actually just the effect of space time being curved.
If you don't notice that space time is curved, it
looks like something is bending the light or changing the
path of the Earth. But it's actually just the curvature
(06:44):
of space time. Space time curves in response to mass,
and if you get enough mass in a small area,
it curves space time so much that things get trapped.
Space time is curved so that like light can't even escape.
It's not like there's so much gravity it even pulls
on photon. It's that space itself is bent so that
inside a black hole, space only points towards the center.
(07:06):
And so this creates the phenomenon we call the event horizon,
beyond which anything that falls in is trapped. It will
only move towards the center of the black hole. And
so this is the defining feature of a black hole,
the event horizon. This is the thing we haven't actually
literally technically observed. We've seen lots of indirect evidence for
black holes, but never actually observe the event horizon. And
(07:28):
beyond the event horizon, we can't tell anything that happens.
We can know the mass of the black hole, we
can know if it has electric charge, we can know
if it's spinning, but everything else is shrouded in mystery.
Speaker 1 (07:38):
We've done eleven of these listener questions episodes so far.
In thinking back, I feel like most of them have
had at least a question about a black hole. What
do you think it is about black holes that keep
people up at night?
Speaker 2 (07:51):
I think it's an incredible prediction of physics, something so
strange and beyond our intuition. But macroscopic, right, like quantum
mechanics makes all sorts of weirds about electrons, what they're
secretly doing while you're asleep, whatever, But we'll never see
those because they're microscopic. You can never observe them. Black
holes are a prediction that are like technically you could
see you could be near a black hole and observe
(08:12):
it and see all this strange effects. So it feels
sort of like magic, I think. And yeah, you're right,
people are fascinated by black holes. It's a significant fraction
of the questions that we get are about black holes.
So yeah, absolutely, it's fantastic. It's wonderful. It's incredible that
we've actually seen them, and we've seen these collisions. I
remember in the late nineties deciding where to go to
graduate school and what to work on, and I had
(08:33):
an opportunity to work on this project Lego the gravitational
wave observatory, and they were looking to see these black
holes merging and the gravitational waves generated by them. And
I remember thinking, they're never going to make that work.
It's crazy, and so I decided not to work on that.
And then of course they won the Nobel Prize. But
you know, hey, maybe if I had worked on it,
it wouldn't have worked out, and they wouldn't have won
(08:55):
a Nobel Prize. So maybe they won the Nobel Prize
because I didn't work on it.
Speaker 1 (09:00):
Anyway, hard to say, do you ever regret not going
into black holes? Or are you totally happy with the
path your life took?
Speaker 2 (09:07):
You know, there are always other options you could consider,
but I'm pretty happy with how everything worked out, and
so yeah, I don't worry too much about the counterfactuals.
But it is amazing that humanity has figured out a
way to observe these collisions. Einstein predicted this decades and
decades ago, but he thought it was going to be
impossible to observe because gravitational radiation is very, very weak,
because gravity itself is not very powerful, and so you
(09:29):
need an extraordinarily sensitive instrument to see this stretching and
squeezing of space time, this gravitational radiation, unless, of course,
you're right next to the black holes colliding, in which
case the signal is very powerful and you're probably dead.
Speaker 1 (09:43):
I feel like that's another thing that gets people interested
in the idea that observing this could kill you, but
if you could survive what's on the other side, I
just feel like it's amazing. But Okay, so we have
observed collisions, and you said that we've observed a lot
of them, and.
Speaker 2 (09:58):
It was a little bit of a surprise when we
saw the first one. You know, we didn't know how
often does this happen in the universe. We're building our
first eyeball for gravitational waves, and how long it takes
the sea one depends on how often they happen, and
there were lots of predictions. Some people predicted that it
would take decades to see one, but they saw one
almost immediately after turning the thing on, and everyone's like,
oh my gosh. Wow. So it turns out these collisions
(10:21):
happen more often than people suspected.
Speaker 1 (10:23):
So does that mean we were totally off in our
predictions for how many black holes there are or how
much they're moving? Around what were we wrong about in particular.
Speaker 2 (10:32):
So we're not sure. Black hole formation is still kind
of mystery. Super massive black holes or things we don't
really understand, so something we're still trying to understand and
we don't understand. Also the distribution of black hole masses.
There seem to be some smaller ones, some bigger ones,
but there aren't intermediate sized ones. So there's a lot
we don't understand about black hole formation, how often it happens,
how often they're close to each other, right, this kind
(10:54):
of stuff, So a lot of really interesting astrophysics is
being opened up by this study.
Speaker 1 (10:59):
No gold locks black holes, and Mark.
Speaker 2 (11:02):
Is interested in what happens when these two black holes
form and where the mass goes, because you know, there's
nothing free in the universe. If two black holes collide
and produce gravitational waves, gravitational waves carry energy. They're stretching
and squeezing of space time, and that energy has to
come from somewhere, and it comes from the internal energy
of the black hole system. These two things are orbiting
(11:24):
each other and for them to collapse down into one,
they have to lose that angular momentum, so they radiate
it away in gravitational waves and Marx's questions trying to
understand where the mass goes, because the mass of the
resulting black hole is not just the sum of the
masses of the two black holes that go in. It's
smaller than that because energy is lost to gravitational waves.
Speaker 1 (11:45):
And we have talked in other episodes about how energy
is mass, but maybe not. It's complicated, is that, right?
Speaker 2 (11:53):
Yeah, Mass is a measure of internal stored energy. Right,
So like a proton's mass, it's not just the mass
of the stuff that makes it up. It's the mass
of the stuff that makes it up, plus the energy
they have relative to each other. In fact, most of
the mass of the proton comes from that energy, the
binding energy of the quarks together. So if you have
a black hole black hole system, two black holes orbiting
(12:14):
each other, the mass of the whole system is the
massive black hole one plus the massive black hole two
plus their relative energy, and that's a lot. There's a
lot of gravitational energy between those two black holes. Let's
say black hole one is forty masses of the Sun,
for example, and black hole two is thirty masses of
the Sun. These are typical numbers. Then the energy of
(12:34):
the whole system would be forty plus thirty plus whatever
energy they have in their relative rotation, and that could
be like thirty or forty or fifty, right, it depends
on the configuration. So the total energy of the system
could be much more than seventy. You could be one hundred,
one hundred and twenty, this kind of thing. But a
lot of that energy is lost when the two radiated
away in order to combine. They have to radiate away
(12:57):
some energy in order to combine, otherwise they would just
or bit forever.
Speaker 1 (13:01):
And are they losing the energy of the black holes
or are they losing the energy that surrounds the black
holes or a little bit of both.
Speaker 2 (13:08):
Yeah, So this is a great question. And this is
what Mark is asking, is like he wants to do
some accounting. Is their mass actually lost? And I think
he's interested in this because people think of black holes
as something that can never lose mass, right at least
in classical general relativity, And so he's wondering, like, is
this a way for mass to escape somehow the black holes?
And it's a little bit tricky. There's a couple of
(13:28):
things to keep in mind. So the final black hole
is smaller than the sum of the two original black holes,
but always larger than either of them. So neither black
hole shrinks. Both black holes grow.
Speaker 1 (13:41):
Nope, no, no, no, You've lost me. Don't they become
one black hole when they merge.
Speaker 2 (13:46):
Yes, they become one black hole exactly, And so there's
no shrinking of the event horizon. Like the final event
horizon is bigger than either of the incoming event horizons. Okay,
so no event horizon is shrinking. It's not like you're
seeing behind the event horizon of either black hole. Both
of them are growing, right, but the final is smaller
than the sum of the two parts. It feels trickier.
(14:07):
It feels like I'm cheating.
Speaker 1 (14:09):
Yes, so I guess what I'm not following is Okay,
when they merge, I no longer think of them as
two separate parts. They're just one part. But it sounds
like you are still trying to keep accounting on two parts,
but now they've become one. So what am I missing?
Speaker 2 (14:24):
Yeah? I think think about it from the point of
view of black hole one. Okay, black Hole one has
an event horizon, and it has a certain mass, and
you could just be in its reference frame and it
has another black hole orbiting it, right, and then that
black hole radiates some energy and falls in and it
gets gobbled up. Black Hole one grows. Right, So we
followed all the rules of general relativity. The event horizon
(14:46):
is not shrunk because it can never shrink, because if
it did, you'd see things inside the event horizon. It
has grown. Its mass has gone up. Right, in classical
general relativity, black hole masses can only go up. So
from the point of view of black hole one, the
fact that black hole two is a black hole is
kind of irrelevant. It's eaten some energy and it's grown.
(15:06):
You can play the same game from the point of
view a black hole two. Right, The thing is symmetric.
Black Hole two grows, it gains mass, it's eating black
hole one. The two merge. The final result is bigger
than black hole two. Everything is happy from a general
relativity point of view.
Speaker 1 (15:21):
Okay, so at the end you still have just one
black hole, but that one black hole is bigger than
black hole one or black hole two were originally.
Speaker 2 (15:32):
Yes, exactly, Okay, and so it feels like mass has
been lost and we're playing some sort of shell game here.
I think there's another thing to understand that might help people,
which is, the mass of the black hole doesn't just
depend on what's beyond the event horizon. You can make
a black hole more massive without crossing the event horizon. So,
for example, say I shoot Kelly into orbit around a
(15:54):
black hole, hypothetically speaking, or Zach. Should we talk about Zaz? Yeah, yes,
of course Zach is in orbit around a black hole. Okay,
Now that black hole's mass grows even before Zach goes
over the event horizon. Right, you tend to think like, oh,
it's has to eat Zach before it grows to add
to its mass. But the mass is a measure of
(16:15):
the energy of the system, right, So the black hole's
mass actually grows before Zach falls over the event horizon.
Speaker 1 (16:23):
So at what point does Zach become part of the
system mm.
Speaker 2 (16:26):
Hmm, Well when he has a relationship to it, like
it's a gravitationally bound to it, than to an external
observer who's like a little bit further away, like it's
a black hole, Zach's system. The whole thing has more
mass than the black hole or than Zach does, and
so you don't have to like add stuff to the
black hole over the event horizon in order for the
(16:46):
black hole to gain in mass. This is actually crucial
for the way that black holes actually grow in the universe.
You might have heard, for example, if you do throw
your husband into a black hole, you'll never actually see
him cross the event horizon because time slows down. And
a lot of people write it and say, all right,
but then how do black holes actually grow if nothing
can cross the event horizon because time slows down. But
(17:07):
the answer is that the event horizon grows before Zack
reaches it. It grows out to meet him. He and
the event horizon approach each other. And so if Zach
was the last thing you ever threw into a black hole,
it's true that he would never cross it, you'd never
see him. But if after you throw Zach into a
black hole, you feel bad and you throw him a sandwich,
and that sandwich approaches the black hole, and as it
(17:29):
approaches the black hole, it pulls the event horizon over Zack, right,
because the event horizon comes out to meet the thing
that's approaching it. Because again, the mass of the black
hole depends on the stored energy, which includes the gravitational
energy it has with things around it. So you shouldn't
think of these things as just like boxes, right, Remember,
mass it's not just like a measure of how much
(17:49):
stuff is inside the black hole. It's a more comprehensive
measure of the energy of that whole system. You don't
have to be over the event horizon in order to
be part of that system.
Speaker 1 (18:00):
So one, the next time you say biology is complicated,
I'm going to just start laughing right away. But okay. Two,
So if you threw Zach ten thousand sandwiches because you
are like you're going to be there for a while,
would the event horizon pass Zach faster than if you
just threw him one sandwich because you don't really care
about what happens in the long run.
Speaker 2 (18:21):
Mm hmm, yeah, absolutely, okay. And if you threw them
in a series, then chicken sandwich number one would pass first,
chicken sandwich number two, then chicken number three, and the
last chicken sandwich would not cross the event horizon. So
it's true, you can't see something cross the event horizon
if it's the last thing that you throw. But in
our universe there's never a last thing. There's always like
(18:42):
more gas and more particles. And that's how black holes
in the universe actually grow, all right, But back to
Mark's question, what's going on here is that the mass
of the whole system. Right, Let's say we start with
our example of a forty and a thirty black hole,
and together they have a mass of like one hundred
and twenty, right, including all gravitational energy and rotational energy.
(19:02):
As they inspirle, they radiate away a bunch of that energy.
So the mass of the system was one twenty. It's
radiated away I don't know sixty. So now the final
black hole is sixty instead of one twenty. So sixty
is bigger than forty and bigger than thirty, but smaller
than forty plus thirty. But all that's happened is that
some of that rotational gravitational energy has been radiated away.
(19:25):
So even though the whole system started out with mass
of one twenty, now it's down to sixty because it's
radiated away half of its energy. I'm just making up
these numbers. They're roughly correct in the order of magnitude,
but I haven't done like any calculations. But that's the
right way to think about it as the energy of
the whole system.
Speaker 1 (19:41):
All right, Well, I think I understand black holes better now,
although I say that after every explanation and then I
get things wrong the next time we talk about it.
But let's see what Mark from Ireland thinks of that explanation.
Speaker 3 (19:55):
Hi, Daniel and Kelly, thank you very much for that
very informative answer to mike question. I think black holes
are really amazing, and merging black holes are even more amazing.
It's incredible that during the final fifth of a second
of their inward spiral, that they are flying around one
another at near relativistic speeds, often up to a rate
(20:17):
of two hundred and fifty orbits a second, and radiate
the equivalent of multiple solar masses of energy in the
former gravitational waves. It really is crazy, crazy physics. Well,
you've answered my questions very well, and thank you both
for taking the time to do so. I'm sure you'll
hear from me again at some stage in the future,
(20:38):
and in the meantime, I'm going to keep listening in.
Speaker 1 (20:57):
All right, So now we are onto by all, from
black holes to black spots. We are talking about patterns
on our furry friends. Let's hear what Simon from Germany
wanted to know about.
Speaker 4 (21:09):
Hi, Daniel N. Kelly Simon here from Germany. Thanks for
a great podcast. They're a fine background to my daily
run in the woods. I have a question here for Kelly,
one that has puzzled me for quite some time, and
it's in relation to the coloration of our furry friends.
So if we take a dog, for example, who is
(21:29):
black and white, and we zoom into the border between
the two colors, presumably we have one skin cell or
hair cell with black pigmentation and the neighboring cell as
a white pigmentation. The question is how is this information
passed down? Presumably the information is contained in a precursor cell,
(21:51):
one splitting into a black and one into a white.
The question is what is the mechanism for this? Thanks
for a great podcast, guys, Keep up the good work,
and I look forward to hearing some insight into this question.
Speaker 2 (22:03):
See biology also has really massively important questions.
Speaker 1 (22:07):
Are you being facetious?
Speaker 2 (22:08):
I can't tell no, I'm trying to make a gravitational pun.
Speaker 1 (22:12):
Oh good, excellent? Okay, sorry, went right over my head.
All right, So this was actually a fairly difficult question
to read about and to try to understand. And it's biology.
So it depends.
Speaker 2 (22:24):
Let me see if I can interpret the question to
make sure I understand what he's asking. Okay, I think
he's basically trying to do some physics here, which is
to like zoom in on the microprocesses involved. He's like
looking at his dog and seeing there's white patches and
black patches and wondering like what makes one bit white
and one black? And he's trying to understand it by
zooming in on the boundary and saying like, there's got
(22:44):
to be a point where there's one cell that's white
and one cell that's black, and that's where the difference is.
And he wants to highlight like what's going on between
those cells to understand why one turns white and black,
but also obviously to zoom out and understand, like how
do you get these patterns?
Speaker 1 (23:00):
Yes, And that's how I interpreted the question as well.
And the answer is that if you are looking at
animal patterns in general, it depends on the colors, it
depends on the pattern shape, it depends on the animal.
But Simon in particular referenced dogs and referenced white and black,
and so I decided that I was going to hone
(23:21):
in on that in particular, all right, because I needed
a foothold for this question. And so in dogs, there
are hair follicles or fur follicles that produce either black
or brown colors, or yellow or white colors. So one
follicle can produce either of those colors depending on the
instructions that it's given. So it's not like you have
(23:43):
different kinds of cells next to each other. It's all
the same cell, but it just is following different sets
of instructions.
Speaker 2 (23:51):
So they're just like printers, and they can get an
instruction for a black hair or a white hair and
they're happy to do it.
Speaker 1 (23:56):
That's right, Yes, exactly.
Speaker 2 (23:57):
Interesting, So who sends the instructions?
Speaker 1 (24:00):
So the instructions are encoded in a gene called a gooty,
and this gene is important for coloration in a lot
of different species, and the gene produces a hormone. The
hormone gets released from the cell.
Speaker 2 (24:15):
I'm a little confused because a gene is part of
your DNA, and so when you're saying the gene produces
a hormone, do you mean the gene when it's transcribed
into a protein is that hormone or the gene when
transcribed into a protein. Is some little machine that makes
the hormone or excuse my naive biologic question.
Speaker 1 (24:33):
No, No, that's a great question. I skipped a bunch
of steps. So, as I understand it, the gene encodes
for a hormone, and so when that gene is essentially
read and turned into a protein, that protein is a
hormone that subsequently gets released from the cell.
Speaker 2 (24:47):
The hair follicle cell, or some other kind of cell
that's controlling the hair follicle cells.
Speaker 1 (24:51):
What I think is happening here is that hair follicle
cells are producing this message and then also sharing it
with nearby cells.
Speaker 2 (24:57):
Oh interesting, Okay, one.
Speaker 1 (25:00):
Gets released and it talks to the nearby cells. If
you are a hair follicle next to a cell that
has just released this hormone, then you produce white.
Speaker 2 (25:11):
Interesting.
Speaker 1 (25:12):
If you don't get that hormone message, you default to
making black or brown?
Speaker 2 (25:18):
Wow? Fascinating right.
Speaker 1 (25:19):
So cells can do either, and so the question is
why are some cells making the signal that say turn
on white and why are some cells not making that
signal and telling nearby cells to default to brown or black?
Speaker 2 (25:35):
I loveI we like follow the chain of logic here like,
this is happening because of that, because of that, because
of that, because of that, and now we're like detectives
following the clues all the way back to the source.
So are you going to tell us who the killer is?
Who is making these decisions about whether to produce this hormone?
Speaker 1 (25:49):
You know, it's biology, so that the answer is never,
you know, kernel mustard. It's much more complicated. So you've
got this a gooty gene, And what determines whether or
not genes are turned on or off is that there
are these regions called promoters, and when something binds to
the promoter, that can turn the gene on. And so
it seems that whether or not this hormone is made
or not has to do with some complicated interactions happening
(26:11):
with the promoter for the genes. And so some cells
have these promoters turned on, so they're making this make
white message, and some genes don't get this promoter turned on,
so they are not giving a message, and nearby cells
make black or brown. Part of why I didn't get
into the details is because it might help you understand
exactly what's happening in this very particular instance. But to
(26:33):
understand coloration in general, that's more a story about promoters
getting turned on or off.
Speaker 2 (26:38):
So in general, then how do promoters get turned on
or off? I mean, this is part of your DNA,
what determines whether or not that DNA is getting turned
on or off.
Speaker 1 (26:48):
In general, we don't understand what's happening super well here,
and we understand this process a lot better in rodents
in birds, and in part that's because we feel much
more comfortable doing experiments on these animals in the lab.
Speaker 2 (27:00):
All that's kind of sad, I know.
Speaker 1 (27:02):
I know it is sad, But then you can also
pick animals that have much simpler color patterns and fewer
colors to boots, and that makes it easier to sort
of get a handle on these sorts of things, whereas
dogs have loads of different color patterns, and so trying
to get a handle on all of the different ways
these patterns can be made is much more complicated. The
manuscript that I read even had a sentence being like,
(27:23):
the situation in dogs is still unresolved, but they're doing
their best to figure it out.
Speaker 2 (27:27):
Well, this is super interesting how we can go from
like totally clues about it to understanding, Oh, follicles can
print either color to understanding what controls what they print,
and then follow that up the chain, and we're still
crawling up the chain. It's incredible.
Speaker 1 (27:40):
It is incredible, And like I said, we've got a
better handle on some species. And animal coloration in general
is sort of fascinating. Like sometimes there are some animals
that get it from their diet. For example, there are
some fish that have red coloration that they get from
the animals that they eat, and it just sort of
like accumulates in their skin.
Speaker 2 (27:57):
That would be amazing if humans, for example, change color
based on what they ate.
Speaker 1 (28:02):
Oh man, Yeah, there'd be very specific kinds of diets
I imagine, And around Halloween you'd eat like a lot
more carrots to get in the mood.
Speaker 2 (28:10):
Would be great, well, amazing. You could get a tan
just by having lunch.
Speaker 1 (28:16):
That would be incredible and probably a lot safer than
what we do now to get tans.
Speaker 2 (28:20):
All Right, So it turns out that Simon's question is
cracked open a huge canyon of unresolved questions in biology.
And not only do we not understand dogs, but the
whole question of how animals get color is still an
active area of research. And maybe having different answers in
each species. Amazing.
Speaker 1 (28:38):
That's right, And so let's see if Simon feels like
he learned anything from this answer.
Speaker 2 (28:44):
It sounds like Kelly read a lot of papers and
learned a lot.
Speaker 1 (28:46):
Kelly read a lot of papers, learned a lot, and
also learned that there's a lot that she doesn't know
about how this stuff works out. So it was a
learning experience for sure.
Speaker 2 (28:53):
All right, let's hear from Simon. Uh huh.
Speaker 4 (28:56):
Kelly definitely did learn something, and I think we as
the audience, I've definitely learned something too. Thanks Kelly for
the great insight into the invisible and incredibly complicated, it
seems biological mechanisms behind something as simple as the coloration
of our furry friends. I think understanding how it works
(29:16):
at this very last step perhaps gives us some insight
into how it works at the very first step. So
if I go back to the very first cell directly
after conceptions, say, where it splits into two, and then
to four, and then to eight and so on, eventually
giving rise to something that resembles a head, a torso,
and four legs, to understand the finer details of how
(29:37):
this information has passed down. How one cell knows to
be a torso while as a direct neighbor knows to
become a leg To understand how this transfer of information
works from one cell division to the next will be
fascinating to find out one day, But that's a question
for another day. Maybe. Thanks Kelly for taking the time
to look deeper into this mechanism and give us some
(29:59):
insight into this very last step of cell division. Gave
up the Great White cause.
Speaker 2 (30:21):
All right, we're back and we're moving on from the
mysteries of biology to the mysteries of the very early universe?
Which one do we understand less?
Speaker 1 (30:30):
Does it really need to be a competition? We don't
understand much about anything.
Speaker 2 (30:33):
Some days it feels like Leonardo wanted to understand the
relationship between particle collisions and the Big Bang. Here's his question.
Speaker 5 (30:41):
Hi, Kelly and Daniel loved the show. I heard particle
accelerators being described as tiny banks as in The Big
Bang but tiny in another podcast by doctor Katie Mack.
I also know we measure the energy of impacts in
giga electron votes, so can we also estimate the energy
of the Big Bang in electron votes?
Speaker 6 (31:00):
And?
Speaker 5 (31:01):
If so, why are we not classifying accelerators in Meli
or Fento banks and Easy because the number would be
too unsatisfying. Grains from Brazil.
Speaker 1 (31:10):
All right, So, Daniel, I remember you telling me once
that when you all turned on the particle collider for
the first time, there was a little bit of a
concern that maybe you would destroy the universe? Is that
because you all thought you were going to kick off
a tiny, big bang.
Speaker 2 (31:25):
Well, you know, anytime you do something that's never been
done before, you don't know what's going to happen. That's
the excitement of research, right, you know, you're exploring the unknown,
you're potentially unleashing something you didn't expect. And so yeah,
there's always a little frison of you know, enthusiasm and
fear when that happens.
Speaker 1 (31:44):
But when I first infect a fish with a parasite,
I don't worry that it's the end of humanity. Like,
the scale feels very different here.
Speaker 2 (31:51):
Maybe you should think bigger, Kelly. Yeah, okay, for those
of you worried at home, we didn't actually worry about
that too much because the collisions we'd do with the
particle colliders are not unusual in nature. They're very high
energy collisions from particles slamming into the Earth's atmosphere all
the time, much higher energy than what we achieve with
the large a drunk collider. We didn't worry that we'd
be collapsing the Higgs field or creating a black hole
(32:12):
or anything like that. But it is a fascinating experiment
because we are recreating conditions of the early universe. They're
also conditions of our current universe, just not as widespread.
And so it's often said that particle collisions recreate the
Big Bang, and that's true in some sense, but there's
also the potential there to sort of underscore misunderstandings about
(32:34):
the Big Bang that we should probably clear up.
Speaker 1 (32:36):
Well, can we start with, like, what is the defining
characteristic of a bang of any size? Small, medium, or large?
Speaker 2 (32:44):
Yeah, that's a good question. You know, in terms of
the Big Bang, the Big Bang is more of a
whiff than a bang, right, because the universe is expanding,
but it's really sort of cooling. It's becoming older and colder.
So the Big Bang is a description of how the
universe is decreasing in density as time goes on. It's
(33:05):
cooling down and getting more dilute. To run the clock backwards,
the universe gets hotter and denser, and we can run
backwards to a certain point what we call the plank
time beyond which we know our theories don't work, and
so everything is a question mark. And that's what we
call the Big Bang is expansion from that moment. So
it's a description of when the universe had very high
energy density. It's not a tiny dot in empty space.
(33:28):
The idea of a big bang, especially if you compare
to particle collisions, makes it sound like something happening at
one location, but the Big Bang was everywhere, and so
the similarity between particle collisions and the Big Bang is
that both have high energy density. Particle collisions of course,
though in just one spot, the Big Bang was everywhere.
Speaker 1 (33:46):
Got it? Okay? And what kind of scale difference are
we talking about in terms of energy between big and
tiny bangs?
Speaker 2 (33:53):
Yeah, so it's a pretty big difference. We compare these
things in a weird unit called electron volts, and it's
sort of a generic unit of energy. You can also
use it to measure mass, because we don't care about
things like the speed of light, and so an electron
volt is our unit, and to calibrate. For example, a
proton has a mass of one giga electron vault, so
a billion electron volts is the mass of a proton,
(34:16):
and collisions that we can achieve here on Earth are
in the scale of ten tarra electron vaults, so ten
thousand times the mass of a proton. And that sounds
pretty big, right, like ooh wow tarra Like that's a big.
Speaker 1 (34:30):
Number, But protons are pretty small.
Speaker 2 (34:32):
Protons are pretty small, exactly, And so the energy of
the Big Bang in the same units is ten to
the sixteen terra electron vaults, so ten to the fifteen
times more energy than the collisions we have at the LHC.
And ten of the fifteen is not a small number,
you know, it's not fifteen times. It's ten to fifteen
(34:53):
ten with fifteen zeros. If your bank account had one
with fifteen zeros in it, you'd be very very rich,
much much much richer than Elon Musk, probably like Elon
Musk squared. So it's very very high energy.
Speaker 1 (35:07):
If particle physicists had enough money, would you guys try
to make a particle collider you could do the Big
Bang in because I'm not sure we can trust.
Speaker 2 (35:17):
You, guys, No, I think we would. And you know,
the higher the energy collision, the more stuff you can make.
Right we don't know what's out there in the sort
of universe's menu of particles. And the incredible thing about
these collisions is that you pour energy in and there's
some sort of like quantum mechanical magic alchemy that happens,
and the universe decides what from its menu to make,
(35:38):
and it just sort of picks randomly from all the
things that it can make, which means that if you
pour enough energy into the collisions, you'll see everything the
universe is capable of making. If you do it often enough,
you don't even have to know what's out there. So
it's like a way to explore the capacity of the
universe without even knowing what it's capable of. You don't
have to leave your house. It's like, hey, make me
(36:00):
everything you can make right here. And as you turn
up that energy, you get to explore higher and higher
on nature's menu. And you could be just below the
threshold and not make the thing because they don't have
enough energy, and then you crank up the energy and
boom it starts to pop out. So Yeah, we'd love
to crank up the energy these things. We're still a
factor of ten to fifteen away from the Big Bang,
(36:21):
which means there could be particles that were made in
the early universe and they're super duper massive and we
haven't been able to make them yet. They could be
made in collisions of cosmic rays in the atmosphere, but
they're very short lived and we don't have detectors up
there to see them.
Speaker 1 (36:35):
So check out Daniels go fundme for the next big
particle collider.
Speaker 2 (36:40):
Leon artists question also asked, can we measure particle collisions
in terms of milli or fempto bangs? And the answer
is yes. So if you define one bang as ten
to the sixteen TeV, then the Large Hadron Collider has
collisions at about ten of the minus fifteen bangs or
one femto bang, which, yeah, doesn't sound very impressive and
not a great way to headline your science funding request.
Speaker 1 (37:03):
I don't know. I think femto bang sounds pretty.
Speaker 2 (37:05):
Cool, but it's also a way to sort of trace
back the history of the universe. Like as the energy
of your collisions goes up and up and up, you
recreate conditions that existed everywhere in the universe further and
further back in time and already ten TV one. Femto
bang is pretty high energy. It takes you all the
way back to like microseconds after the Big Bang because
(37:28):
the energy started to fall off really really quickly. It
becomes more gradual as time goes on. So we are
probing conditions in a very very early universe microseconds after
the Big Bang.
Speaker 1 (37:40):
Well, let's see if Leonardo is impressed by femto bangs.
Speaker 6 (37:45):
Hello, I'm also in teen Kelly, I'm also impressed by
fento bank. Also, thanks for clarifying the differences between a
particle collider and the early universe. I actually never considered
that there could have been particle so massive. If that
we will likely never be able to recreate. Thanks.
Speaker 2 (38:04):
All right, and today we have a special bonus question
on gravitational and velocity based time dilation from ASTHMT. We
decided we could squeeze in a fourth question for y'all,
So here's Ozma's question about time dilation.
Speaker 7 (38:19):
Hello, I'm a smith, and my question is what would
happen to time dialation if both high velocity and strong
magnetic feeling interacted simultaneously. Would this cost time to slow
down even more significantly or would there be no additional effect?
Thank you?
Speaker 1 (38:35):
All right? So Daniel, I have been listening, well you talk,
and I remember you told me there's two kinds of
time dilation, gravity and velocity. But my brain is a sieve,
so remind me what the difference between those is.
Speaker 2 (38:50):
Right, So there are two ways that clocks can appear slow. Now,
clocks that you hold, that you have with you always
run the same speed. But if Kelly gives Zach clock
and then shoots them out of a cannon a very
high speed relative to her, she will see Zach's clock
running slow because velocity time dilation says moving clocks run slow. Now, Zach,
(39:12):
with this telescope looking back at Kelly's clock, will disagree.
He'll say, no, no, Kelly's clock is running slow. So that
kind of time dilation is symmetric, meaning both wiener Smith's
see the other one's clock running slow. And at least
to this sort of confusion like whose clock is really
slower and the answer is there is no really slower,
they can argue forever and both be right. So it's
(39:33):
sort of a marital trap for the two of them.
Speaker 1 (39:35):
Yeah, that's not great.
Speaker 2 (39:37):
But the other kind of time dilation, gravitational time dilation,
is asymmetric, which means everybody can agree on it. So,
for example, if Kelly does drop Zach near a black hole,
she'll see his clock running slower, but he will see
her clock running faster. They agree in this scenario, but
whose clock is running slower or faster? Both of them
(39:58):
see their own clocks running at normal speed. And so
the cool thing here, and this is Ozma's question, is like,
what happens when you have both? Do they constructively interfered,
destructively interfered to his universe? Explode? What happens?
Speaker 1 (40:10):
I hope The answer is Kelly is right. Whatever time
Kelly says is the correct time.
Speaker 2 (40:18):
The answer is they both contribute. So let's say, for example,
that Kelly launches Zach into orbit. Right now, Zach is
going really, really fast, and so his velocity means that
his clock runs slower than clocks we have here on
Earth from our point of view. Okay, but he's also
further from the gravitational well of the Earth, so his
(40:41):
clocks will run faster than ours. Because of the gravitational
time dilation is less so we have actually gravitational time
dilation right here on the surface of the Earth. Because
of the Earth, we're all experiencing it all the time.
Clocks out in deep space run faster. So from Kelly's
point of view, Zach's clock runs slower because of velocity
and faster because of gravity, and the gravity actually wins out.
(41:05):
So the velocity time delation is like seven microseconds per
day if he's up with GPS satellites, and forty five
microseconds per day the other direction due to gravity. So
overall gravity wins.
Speaker 1 (41:19):
So when I shoot him into orbit, because gravity is
winning and it makes things faster, he should still be
on time or early to the meetings. I let no
excuse for being late, Is that right?
Speaker 2 (41:30):
I really feel like I don't want to get in
the middle of here. Physics is not going to solve
your marital.
Speaker 1 (41:35):
Problems, all right, all right, but baby sandwiches, well.
Speaker 2 (41:40):
Sandwiches yet well exactly now, from Zach's point of view,
both of the effects make Earth's clocks slower. It's fascinating
because from the Earth's point of view, we see the
effects having different directions. But from Zach's point of view,
he sees both effects having the same direction. He sees
us moving quickly, which means our clocks run slow, and
he sees a closer to a gravitational well of the earth,
(42:03):
which means our clocks run slow.
Speaker 1 (42:05):
Oh see, now, I feel like you're citing with zech.
This is no excuse.
Speaker 2 (42:11):
I feel like I need my lawyer present.
Speaker 1 (42:15):
All right, everybody, thanks for playing. Just a reminder that
you too can send us questions at questions at danielant
Kelly dot org. We answer every question, some of them
end up on the show and we can't wait to
hear from you.
Speaker 2 (42:26):
And some of our questions come from conversations on the discord.
We encourage you to join our discord, where people ask
and answer questions and make a bunch of nerdy jokes.
You can find the invitation on our website Daniel and
Kelly dot org.
Speaker 1 (42:45):
Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We
would love to hear from you, We really would.
Speaker 2 (42:52):
We want to know what questions you have about this
Extraordinary Universe.
Speaker 1 (42:56):
We want to know your thoughts on recent shows, suggestions
for future shows. If you contact us, we will get
back to you.
Speaker 2 (43:03):
We really mean it. We answer every message, email us
at Questions at Danielankelly dot.
Speaker 1 (43:09):
Org, or you can find us on social media. We
have accounts on x, Instagram, Blue Sky and on all
of those platforms. You can find us at D and
K Universe.
Speaker 2 (43:19):
Oh be shy right to us
Hosts And Creators
Daniel Whiteson
Kelly Weinersmith
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