January 21, 2025 • 43 mins
Daniel and Kelly answer questions about binary star seasons, meat wasps and freefall.
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Speaker 1 (00:06):
How do some bees make meat honey? What are tapeworms
up to in my tummy?
Speaker 2 (00:11):
Can light escape from a black hole? What process produces coal?
Speaker 1 (00:15):
Did Franklin hang that key from a kite? Why is
dark chocolate better than white?
Speaker 2 (00:20):
How do moles smell underwater? Why is the planet getting hotter?
Speaker 1 (00:24):
How can humans live on Mars? What's the hold up
with flying cars?
Speaker 2 (00:28):
The current state of space law? The powerful mantis, shrimp claw?
Speaker 1 (00:32):
Biology, physics, archaeology, forestry, really anything other than chemistry?
Speaker 2 (00:38):
What diseases do you get from your cat? Well, we'll
find the answers to all of that.
Speaker 1 (00:43):
Whatever question keeps you up at night.
Speaker 2 (00:45):
Daniel and Kelly's answer will make it right.
Speaker 1 (00:48):
Welcome to another Listener Questions episode on Daniel and Kelly's
Extraordinary Universe.
Speaker 3 (01:07):
Hi.
Speaker 2 (01:07):
I'm Daniel, I'm a particle physicist, and I've never read
a poem on the podcast before.
Speaker 4 (01:12):
Hi.
Speaker 1 (01:13):
I'm Kelly Wiener Smith. And my husband just assumed that
I'd be so bad at writing poems that when I
read it out loud to my daughter, he left the
room just so that he wouldn't be embarrassed. But you
know what, I had fun.
Speaker 2 (01:25):
I hope he's blushing somewhere. Whenever he's listening to this, he.
Speaker 1 (01:28):
Might skip all of our Listener Questions episodes from here
on out. But that's all right. I had a good time.
Speaker 2 (01:33):
Well that's too bad, because those are my favorite episodes.
I love hearing what people are wondering about, helping them
unravel their confusion and getting to the topics that are
really in people's minds. It's my favorite way to interact
with our audience.
Speaker 1 (01:47):
I love it as well, and I'm particularly excited about
this Listener Questions episode. You know, one because my daughter's
questions included and that's pretty cute. But two because we
got a biology question for me that I was she
is completely unaware of this group of species and they're
so creepy and right up my alley and it was
so much fun.
Speaker 2 (02:06):
All right, Well, let's not waste any more time. Let's
dig into it today. We have questions about seasons on
Binary Star systems, about meat, wasp honey, and about how
gravity actually works.
Speaker 1 (02:19):
Let's do it.
Speaker 2 (02:19):
So our first question is from Aida. She's ten years
old and she lives in Virginia, and I think she
knows Kelly pretty well.
Speaker 1 (02:26):
Great place to live, I'll just throw that in there.
Speaker 2 (02:30):
Here's Ada's question.
Speaker 5 (02:32):
Hi. I'm Ada, I'm ten years old. I have a
question for you. What would seasons be like if you
were on a planet in a solar system that had
two sons? Thank you?
Speaker 2 (02:43):
All right? I like how she gets right to the point.
Speaker 1 (02:46):
Yes, she's very succinct. I like that too.
Speaker 2 (02:48):
Is she reading a book about life on a solar
system with two sons? Or where do you think this
question came from?
Speaker 1 (02:54):
Gosh, you know, I'm sure it didn't come out of nowhere,
but I don't know where she heard about solarsis with
two suns. That sparkedness. Could have been science class at school.
Speaker 2 (03:03):
Maybe she's writing a science fiction novel and she needs
some science consultation.
Speaker 1 (03:08):
That's right, Yes, and she reached out to the right person.
Speaker 2 (03:10):
Yeh, she certainly did. So let's dig into it first.
Let's remind ourselves why we have seasons on Earth, and
then we can teleport ourselves mentally to a solar system
with two stars and think about that one. So, on Earth,
the reason we have seasons is because the Earth is
tilted right. The Earth goes around the Sun, and there's
a plane there where all the planets go around the
(03:32):
Sun in the same plane, and the Earth also spins,
but the axis that it spins on is not perfectly
perpendicular to the plane of its orbit, so it's tilted
a little bit. It like leans over. Now, the Earth
is a sphere, so you know what is really leaning.
It's still a sphere when it's tilted. But what's leaning
is that axis of spin, that axis that controls the
(03:53):
day night cycle. So what's closer to the Sun is
the Northern hemisphere the spin lets you define a northern
and the southern hemisphere, Then the Northern hemisphere is closer
to the Sun during the summer, and the Southern hemisphere
is further from the Sun during the Northern hemisphere summer
and the Southern hemisphere's winter. It's not actually accurate to
say that the Northern hemisphere is any closer to the Sun.
(04:14):
Is just more exposed to the Sun because it's leaning
that direction, got it?
Speaker 1 (04:18):
And you know, I've got to admit that every once
in a while, when I talk to like the few
friends I have in Australia, I still forget that they're
experiencing the opposite season that we are up here in
North America. And we regularly have a disconnect.
Speaker 2 (04:31):
Yeah, exactly. And so if we didn't have a tilt.
For example, if the Earth's axis of rotation was perfectly
perpendicular to the plane of its orbit, then you wouldn't
have any seasons. You just always have I guess spring
or fall. Right, the days would be the same length
all year round. Going around the Sun wouldn't change your
experience at all.
Speaker 1 (04:51):
No seasons, totally boring, just like living in California. You
knew where that was going halfway through the sentence.
Speaker 2 (05:00):
Exactly, we'd all be happy all year long, right, it'd
be amazing, so dull. And there are other tiny factors
that also affect the weather and the seasons, things like
the elliptical orbit, or the Earth doesn't orbit in a
perfect circle around the Sun. It's an ellipse, which means
sometimes it is closer to the Sun and sometimes it's
further from the Sun. But this is a smaller factor
(05:23):
than the tilt, which really dramatically changes how many hours
of sunlight you get every day. The Earth is closest
to the Sun in January and furthest from the Sun
in July, so actually that counters the effect. It makes
the summer slightly less severe and the winter's slightly less severe.
Speaker 1 (05:39):
Is that why the year starts in January? Or did
that have nothing to do with the calend No.
Speaker 2 (05:45):
That's totally random. Yeah, Oka's totally right. And also the
Earth tilt processes a little bit. It's not always in
the same direction. It itself rotates a little bit, like
a wobbly top. These are small factors, and that's affected
by like the Jupiter and all sorts of other stuff.
So mostly the Earth has seasons because it's tilted, So
the northern hemisphere is getting more light and the southern
(06:07):
hemisphere is getting less light during the northern hemisphere summer.
All right, but that's a simple system, single planet going
around a single star. So what about a binary star
system in Ada's mind?
Speaker 1 (06:18):
Can I back you up for a second? Are most
planets tilted so like the Moon has a very little
bit of a tilt. Is Earth weird having a twenty
three point four degree tilt?
Speaker 2 (06:27):
It's not weird to have a tilt like Urinus is
tilted much more dramatically ninety seven degrees, basically totally on
its side. Other planets are tilted more or less. The
tilt we think comes from being hit. Like everything in
the Solar System formed together from a big swirl. That's
why everything is rotating in the same plane, and most
of the planets are spinning in the same direction they
(06:48):
move around the Sun, which is the same direction that
the Sun is spinning itself. The whole Solar system is
one big swirl, which then coalesces into a star and
planets which all have the same swirl. But then you
can get hit by something from outside the Solar system
and it can knock you off axis a little bit.
So we think that's probably the source of the Earth's tilt,
and other planets tilt as well.
Speaker 1 (07:09):
With all the stuff that's colliding, Would it be reasonable
to expect that having no tilt would be rare because
there's so many collisions that probably knock you off angle.
Speaker 2 (07:17):
Yeah, As the Solar system forms, it's a little chaotic
and things hit each other, so the average tilt is
going to be zero, but it's unlikely for everything to
have exactly zero tilt. Got it just the same with it,
Like all the solar systems in the galaxy on average
have zero tilt relative to the plane of the galaxy,
but most of them are tilted relative to the plane
of the galaxy. They're not all aligned with the actual
(07:39):
rotation of the galaxy.
Speaker 1 (07:40):
All right, So let's move on to systems with two sons.
Speaker 2 (07:43):
All right. So system with two sons sound exotic, right,
You're like, ooh wow, two sons, how cool, But the
truth is that they're not actually that rare. Binary star
systems are all over the galaxy. It's a significant fraction
of the stars in our galaxy have a partner star.
And the reason is that that big cloud of gas
that collapses to give you a star usually it's part
(08:04):
of a much bigger cloud. So stars are born together.
Often you have two, three, four, five stars all born together,
which begin a complicated swirl as they're forming. So you
have these nurseries. We have a lot of star forming
happening at the same time, and so stars are born
with partners. And the reason we have a lot of
binary star systems is that it's basically the most number
(08:26):
of stars you can have in a system and have
it be stable. Like you can have two things orbiting
each other and have that be stable, like the Earth
and the Sun or a star and another star. But
you add a third object and it becomes chaotic, it
becomes really complicated and unstable. So if you have three stars,
for example, what's very likely to happen is one of
them is going to get ejected and you're going to
(08:48):
end up with a single star and then a pair
of stars. So you have a lot of binary star
systems out there, not very many trinary systems or quaternary systems,
or not even know the descriptions for five or more stars.
Speaker 1 (09:01):
So why is it more likely to get ejected than
to get pulled into one of the other two stars
and then just make like, I don't know, a big star,
a big explosion.
Speaker 2 (09:10):
Yeah, well that could happen also, but you know, stars
are small compared to the distances between them, and so
actual collisions are pretty unlikely, but they can spiral in
and combine. That certainly does happen as well, But there's
just many more outcomes where they get ejected, and just
like in our Solar system, there's been chaos. We think
probably there was another giant planet which got ejected from
(09:31):
the Solar System because of the interaction between all the planets.
So you have a lot of binary star systems out there,
and then you have to think about the planets around
those binary stars, and it becomes tricky already because now
the planet is sort of like that third object. So
you might wonder like, hey, isn't the planet just going
to get ejected the way like a third star would
get ejected, And the answer is yes, it's not easy
(09:52):
to have planets around binary stars in a stable way.
There's two ways to do it, and both of them
basically make it look more like a binary star system.
So one solution is you have the two stars near
each other and the planet is far away, so it's
sort of like, yeah, there are three objects there, but
really it's sort of a nested set of binary systems.
You have like the stars on one side and the
(10:14):
planet that are orbiting each other, and then inside the
sort of star system, you have two stars moving near
each other. That's one situation, basically, like replace the Sun
with two stars close to each other or closer to
each other than to the planet. The other possible configuration
is you have a star and a planet like the
Earth and the Sun, and then you have another star
that's much further away, so like put a star near
(10:36):
Pluto or something much further from the Earth than the
Sun and then it's far enough away that it's not unstable.
Then you have like again a nested set of binary systems.
You have three objects, but really it's like two objects
acting as one and then in a binary system with
the third object.
Speaker 1 (10:54):
Okay, so then let's talk about seasons. In the first
scen area, where you have two stars that are right
next to each other, do they act like one just
megastar when you sort of aggregate their effects.
Speaker 2 (11:05):
Yeah, they act like one megastar. It's going to be
very similar to as if you had one bigger star.
It's going to be different and more dramatic in terms
of like sunrise and sunset. Sunrise will be longer and
sunset will be longer, and there'll be times when you
have like one star above the horizon and one below,
so you could have effects like you could have a
sunrise where there's already a star in the sky, and
(11:27):
then you have basically two sunsets, one more dramatic than
the next. So that would be really cool, but it
wouldn't really affect the seasons very much, right because the
planet's relationship to the star is basically the same. If
you have a tilt and you have an orbit that's
going to determine your seasons. So in that situation where
you have a planet around a binary star system where
the stars are close to each other and further from
(11:48):
the planet, the seasons are going to be very much
like here on Earth.
Speaker 1 (11:51):
I feel like it would be amazing to wake up
to a sunrise with two stars in the horizon. That
sounds really cool. But all right, So then our second scenario,
you say, there's one sun that's kind of close to
the planet and another sun that's super far out. Is
it far enough out that it doesn't really impact climates
and seasons anymore?
Speaker 2 (12:11):
Unfortunately? Yeah, So the boring answer is for there to
be a planet in this situation, that star has to
be kind of far away. The closer you get it,
the more dramatic and the impact on seasons and day
night stuff, etc. But also the more unstable it is. Like,
if you have the planet be the same distance from
both stars, so it's like very dramatic, then that system
is totally unstable and it's not gonna last for very long.
(12:34):
So you got to push that second star kind of
far away, which means really it's gonna be in the
sky more like a bright star. Than a real sun
and not really gonna affect your seasons. You're gonna have
one totally dominant star and then a second star that's
gonna sometimes make the night a little brighter or even
the day a little brighter, but it's not gonna have
(12:54):
that much effect. But you know, in a science fiction
sort of inspiration, we can move that second star in
as as much as possible and pretend that it does
have some impact because there's some crazy dynamics that happen
in that scenario.
Speaker 1 (13:07):
Okay, let's go for it. What is that like super winter?
Speaker 2 (13:12):
Yeah, exactly. If you think about the periods when you
have sunlight, that really is what determines the seasons. Right
in a single star, single planet system, it's the number
of hours per day of sunlight you get that determine
the seasons. And in the summer you're getting more sun.
In the winter, you're getting less sun. Now put that
second star around, say we have the second star, you know,
in Mars orbit or something crazy, then you're going to
(13:35):
be getting sunlight all sorts of weird configurations, like there
can be parts of the year where each star is
illuminating a different side of the planet. Put the planet
between the two stars. Right, they're all in a line.
You have star, planet Star, then every part of the
surface is seeing a star. Right, It's like the whole
world has noon at the same time, right, which would
(13:56):
be crazy. So you have periods where the whole planet
is seeing star, and then other scenarios where like in
a line it goes star star planet where half of
the planet is seeing both stars at the same time,
and if they're both pretty close, that's gonna be superday.
That's like super noon, right, and that's gonna be very intense,
super duper hot. And also you'll get a weird effect
(14:19):
there where potentially the stars eclipse each other. So like
you know, we have solar eclipses and lunar eclipses, this
would be like a stellar eclipse where one sun is
behind the other sun briefly. That would be awesome.
Speaker 1 (14:31):
Don't look at either.
Speaker 2 (14:36):
But I actually looked up a simulator to try to
figure out exactly what would happen through the year, and
it depends crucially on the orbit of that second star.
If that second star has a period of about a year,
like the same as the planet's orbit, then you're gonna
have a regular cycle. But you're gonna have times in
the year where even at the equator you have no darkness,
like you see one sun and the planet spins and
(14:57):
you see the other sun. And so that's going to
be very summary, right, because it's all about the hours
of sunlight you get and other parts of the year
where you're seeing both suns at the same time, so
you're getting fewer hours of daylight, but they're more intense,
they're brighter. So you're gonna have these really weird periods.
I don't know how the plants would respond to that,
or how you would evolve in that kind of.
Speaker 1 (15:18):
Configuration circadian rhythms, mm hmm.
Speaker 2 (15:21):
It's gonna be a total mess, but it would be regular,
you know. And if, for example, the second star has
a longer period, it takes longer to go around that
first star and the planet, then its affects can slide
through the year, right, It's not like every June we
have double sun, every January we have one sun. It
can slowly offset and that must really affect like the
(15:43):
development of a civilization, you know, because we use the
regular seasons, and the regular day night cycle really is
a way to tell time. So either you have to
have much more complex mathematics before you can even begin
to use a calendar and develop it. Or maybe you
get some art or quicker because the calendar is more
complicated and it inspires more interesting mathematics. But the short
(16:03):
answer is that the seasons are going to be intense
and complicated, and it depends on a lot of the details,
exactly how fast that second star goes around the first star.
Speaker 1 (16:12):
I wonder if it would hinder the establishment of civilizations,
because like being able to plan things like when you
plant your crops seems really important. I wonder if we'd
all be like wanderers because planning just isn't worth even trying,
but really fun to think about it. You know, there's
got to be a couple of sci fi novels in.
Speaker 2 (16:27):
There, Yeah, exactly. And you know there's the famous book
The three Body Problem, where they have essentially this question,
except it's actually the four body problem because they have
three stars and a planet. I don't know why they
like couldn't figure out how to count to three. It's
already complicated enough with two stars. You don't need a
third star.
Speaker 1 (16:47):
Yeah. Well, when Ada's done with her math homework, will
have her listen to this explanation and hear what she
had to say.
Speaker 2 (16:56):
Maybe we should have her on in real time for
a follow up. Let's do it, hi Ada, thanks very
much for your question. I was curious what you thought
about our answer and if you have any follow up questions.
Speaker 5 (17:10):
I understood like what I heard when I listened to
the podcast, m H. And I do have one follow
up question.
Speaker 2 (17:25):
Oh goodie, what is it?
Speaker 6 (17:26):
So?
Speaker 5 (17:28):
Was our sun in this our source system like part
of a different source system and then was it ejected
out or was it just not like that?
Speaker 2 (17:45):
Yeah, that's a great question. Unfortunately we don't know the answer.
Most stars are born with other stars nearby. There's like
sibling stars sometimes two, three, five, seven, as part of
a big nursery, and then they're separated, as you know,
gravity lings them around. But we don't know the history
of our star that far back, so probably it was
(18:05):
born with other stars, but we don't actually know. Maybe
one day we'll figure out some way to figure it out,
but for now we don't know the answer. Thank you,
thanks so much for your question.
Speaker 1 (18:32):
All right, so now for something absolutely totally different, we
have a fantastic question from listener James Palmer, and it
is a question about meat bees otherwise known as vulture bees,
which I had not heard of, but is absolutely right
up my alley. So let's hear the question.
Speaker 4 (18:50):
Hey, Kelly and Daniel, I have a burning desire to
know everything about meat wasps. I just heard about them,
and I feel like there's a lot to discuss here,
Like apparently they are carnivorous and the eat on like
flesh and like maybe it's rotting. Then they use that
to make their honey and stuff like meat honey. Please
tell me everything.
Speaker 1 (19:12):
Meat honey, Daniel. You're dying to know about meat honey.
Speaker 4 (19:16):
Right.
Speaker 2 (19:16):
Well, you know, we have lots of different kinds of
honey here in California, and often it's sold to us
by promoting the kind of flowers that the bees visit,
like ooh, this is lavender honey or wildflower honey, and
you're supposed to imagine that you can taste the lavender
as you're eating the honey. And so I'm wondering, now,
meat bee honey, is it gonna taste like pepperoni or
what's going on?
Speaker 1 (19:36):
Oh gosh, you know, to be honest, I would never
try it. But there's not a lot of honey that
is meat honey. So there's a lot of bees that
make something called honey, but there's only three species that
do this meat honey thing exclusively. So I think maybe
we should start with how honey is made. Yea, because
I actually didn't understand this very well.
Speaker 2 (19:57):
I have this naive understanding that like bee eat pollen
and then do something internally and then vomit up honey.
How wrong is that?
Speaker 1 (20:04):
Yeah? I thought that too, Okay, totally, like almost one
hundred percent. Okay, so that was my thought too. Okay,
So let's start with the European honey bees as an example. Okay,
So this is APIs Melfera, and what they do is
they go out and they go to flowers, and the
flowers produce both nectar, which is like sugar water, and pollen,
which has a lot of protein. And so these fill
(20:25):
two very different rolls for the bees. So they get
their carbohydrates from the nectar, okay, and that's gonna become honey,
and then the pollen is their protein source. And sometimes
the pollen like gets in the honey. It almost sounds
like it's accidental, but mostly the honey is from the nectar.
Not from the pollen, but.
Speaker 2 (20:44):
The bees also eat the pollen. I thought the pollen
was incidental and going along for a ride, and it
was part of the plants deal with the bees, Like
you can eat the nectar, but then I'm gonna get
the pollen all over you and you're gonna drop it
on another flower and help us reproduce.
Speaker 1 (20:57):
No, they eat it too. Oh no, they eat it
and they feed it to like the baby bees, and
so it's like a very important protein source. I didn't
know that either. And actually there's four different kinds of bees.
There's the honey bees, the orchid bees, the bumblebees, and
the stingless bees. And they're all categorized by having what
are called corbicula and these are like chunky thighs with
(21:19):
like a way to like stick the pollen on there.
And so like I saw a bee on one of
our flowers the other day and I was like, what
is this orange? Like it's like they've got bling on
their hips. I know, as an ecologist, I should have
been like mortified that I didn't know what this was already.
But anyway, those are like four carrying pollen around so
they can bring it back to the.
Speaker 2 (21:37):
Hive, I see, And so do the plants get anything
out of it? I thought bees were pollinators.
Speaker 1 (21:42):
Yeah, I think some of it still like falls off
and lands in the right place, so the pollination still happens.
But the bees aren't moving the pollen around as a favor.
It's more like incidental. So that's how nature. No one
helps anyone out in nature unless they have to, all right.
Speaker 2 (21:57):
So bees drink pollen and then they use that to
make the honey. How do they actually make the honeyes
that inside the bee? Or is that in one of
their little hexagonal cooking vats.
Speaker 1 (22:07):
Bees drink nectar. They don't drink the pollen.
Speaker 2 (22:10):
Oh sorry, right, yes, okay.
Speaker 1 (22:11):
That's okay. Or they sometimes drink a honeydew, which is
this like sweet fluid produced by insects as like a
way to attract organisms that like protect them from natural enemies.
They collect it in this special organ where they collect
all of this sugary water, and you know, they can
use it a little bit for like their flight to
get from place to place, but they're you know, trying
(22:31):
to bring it back to the hive. So they fill
up this organ and I think that something like half
of their body weight can end up being this sugary water.
But the sugary water is nowhere near concentrated enough to
be honey. So what they do is they bring it
back to the hive and they regurgitate it to bees
whose job it is to try to get some of
the water out and concentrate the sugars more. And so
(22:55):
those bees they like start kind of partially regurgitating it
and blowing these like bubbles that increase the surface area,
so some of the water evaporates off it.
Speaker 2 (23:04):
Didn't know that the physics of honey look at that, Yes, right, And.
Speaker 1 (23:08):
I hadn't imagined that so much of honey involved vomit.
But there you go, so much fun hanging out with biologists.
Speaker 2 (23:16):
When I'm vomiting, I'm not busy also trying to concentrate
it and evaporate it. So I have like gooey or vomit.
I guess that's what a bee does.
Speaker 1 (23:24):
I mean, you're not so great at multitasking. Too bad.
Speaker 2 (23:28):
I'll work on that. I'll work on that. You know,
good to have goals. Yeah, all right, So bees vomit
up the nectar, and then other specialized bees help evaporate
and concentrate it into honey. So that mean that honey
is just nectar that's been concentrated down or is there
some fermentation that also happens.
Speaker 1 (23:44):
That's just one of the stages of evaporation that gets
a little bit of the water out, and then when
they store it in the combs, like the you know,
honey combs, I'm under the impression that some more evaporation
happens there. So bees produce a little bit of heat
by like, you know, shaking their wings really fast. That
also produces some airflow over the honeycombs, and that combination
of heat and then air moving throughout the colony and
(24:07):
then sort of back out of the hive, that finishes
evaporating off the water until you get to a point
where you've got enough concentrated sugar that you've got honey.
Speaker 2 (24:15):
Wow. Fascinating.
Speaker 1 (24:17):
Yeah, I didn't know any of that. That was awesome.
Speaker 2 (24:19):
So then it makes sense that if I'm eating the
honey from bees that visited lavender, it shit tastes like
lavender because it really is like concentrated lavender nectar.
Speaker 1 (24:27):
If lavender nectar smells like lavender, I don't know that
it does. And I'm one of those people who has
had honey from different places and been like, it's all
honey to me. I don't have a delicate paletate.
Speaker 2 (24:39):
Okay, So now tell us about meat wasps. Where do
they get their supplies to make honey?
Speaker 1 (24:45):
Okay?
Speaker 2 (24:45):
So I'm terrified of this answer, by the way.
Speaker 1 (24:48):
Yeah, all right. So the best honeymakers are the European
honey bees, the best in terms of like producing honey
that humans like, but a bunch of other kinds of
bees they make similar honey, but often their honey is
nowhere near as like concentrated with sugars. It's more watery.
And there's a group of bees called the stingless bees,
and now we're getting closer to the vulture bees. So
the stingless bees they make honey, but their honey tends
(25:11):
to be more watery, and instead of storing it in
those combs, they make these little waxy pots, and it's
harder to get it out of those waxy pots, and
it's like more watered down when you do. So people
did still keep these bees for sugary fluids, but as
soon as honey bees came along, a lot of the
stingless bees that do this more watered down, harder to
(25:32):
get honey, they became less popular to culture. But so
these stingless bees, they also get their nectar from flowers,
but there's a group in the genus Trigona where they
seem like they're less interested in flowers. So instead of
going to flowers for nectar, they get their sugars from
things like rotting fruits. They'll like take the sugars from that.
(25:56):
And instead of getting pollen, they get their protein from
dead animals, dead vertebrates in particular.
Speaker 2 (26:04):
I see. So that's why they're called vulture bees, because
vultures are scavengers. They don't kill anything. They eat already
dead stuff. So these vulture bees will get their protein
not from pollen, but from dead animals.
Speaker 1 (26:13):
You're saying, that's right. And they'll get their sugar, which
they used, you know, like make their honey stuff. They
get that from things like writing fruit are free they find, Okay,
So then the question is do they make meat honey?
This is important and the answer I think is maybe.
Speaker 6 (26:31):
Oh.
Speaker 2 (26:32):
Really.
Speaker 1 (26:32):
So there's only three species of these vulture bees, and
they're all in the same genus, they're all closely related.
It does turn out that there's a fair number of
stingless bees that where like, if meat is left out,
they'll go ahead and get some protein from it, but
they're not required to get protein from it, so they're
called facultatively necrophagic, which means they'll like eat dead stuff
when they've got the chance, but they don't have to.
(26:54):
But these vulture bees are obligately necrophagic, so they have
to eat dead stuff. And currently they're really good at it,
Like they've got ways to sort of attract other members
to come so that they can like very quickly with
these specialized mouth parts scrape a bunch of like rotting flesh.
Oh my god, yeah, your face is like priceless.
Speaker 2 (27:12):
It should be called nightmare bees. Yikes.
Speaker 1 (27:15):
Yes, it's intense pretty metals. So then it's a little
bit unclear what happens. So I found a nineteen eighty
two paper that described what they were doing, and it
said the bees masticate and consume flesh at the feeding site.
They do not carry pieces of flesh to the nest,
but appear to hydrolyze it with a secretion produced by
(27:36):
either mandibular or salivary glands, which gives the feeding site
a wet appearance. Side note iw.
Speaker 2 (27:44):
That means they're slabbering right their slabberry and they have
meat slabber.
Speaker 1 (27:47):
They've got meat slabber, and their saliva is starting the
process of breaking down the meat. That's what that means.
And that says individual bees captured well feeding, then forced
to expel the contents of their crop. So essentially they
made these meat bees. Through up, we're carrying a slurry
of flesh measuring between thirty seven and sixty five percent
dissolved solids by volume.
Speaker 2 (28:07):
So a slurry of flesh. Isn't that like a nine
Inch Nails album title or something.
Speaker 1 (28:14):
I feel like we have to get in touch with
prent Resnor now and find some way to convey this
to him.
Speaker 2 (28:19):
Oh boy wow.
Speaker 1 (28:21):
And so then the question is how do they store
it when they get back. So I've read this paper
from twenty twenty one and they were laying out some
different hypotheses for what happens. It looks like that meat
slurry gets stored in pots. Maybe it gets mixed with
some of the sugary stuff they collect. I think at
the end of the day, it's not really clear what
they do how it's stored how long it's stored, but
you probably could say they make something called meat honey,
(28:43):
like they're taking that flesh slurry, they're storing it in
these pots. It looks like it quote unquote matures for
about two weeks into a paste that is also a
little bit sugary. So they do appear to be making
something like meat honey. Let's go for it. Looks like
part of this process and if your wife we're here,
(29:03):
maybe she'd be excited about this part. Part of it
appears to involve the microbiome. So these vulture bees have
microbiomes that include acidophilic bacteria, so bacteria that do really
well in acidic environments. And you find similar categories of bacteria,
they're not the exact same species, similar categories of bacteria
(29:23):
in the guts of like vultures. So it seems like
there's some kinds of bacteria that team up with organisms
that eat dead flesh to sort of help process it
and maybe also help make it safer, because bacteria that
get to the flesh first start producing like toxins maybe
to ward off these competitors, and these acid loving bacteria
sort of help make it all happen, and your face
is just priceless.
Speaker 2 (29:44):
Right now, I'm so glad I don't eat breakfast because
I'd be throwing it up into breakfast slurry right now,
and some bees could come along and make breakfast.
Speaker 1 (29:52):
Honey, meat honey, and so James, I have to thank you.
I had never heard of these before. And let's go
ahead and hear if you learned everything you wanted to
know about meat honey, and.
Speaker 2 (30:06):
If you're ever gonna eat honey again.
Speaker 6 (30:09):
I think it's safe to say that you taught me
everything I asked for and a lot more. So thanks
ver so much for that, guys. I appreciate it.
Speaker 2 (30:31):
All right. Our last question comes from Hans in the
Netherlands who has a nephew in Perth, and they've been
disagreeing about which direction the Earth is accelerating and how
gravity actually works. Let's hear the question from Hans.
Speaker 3 (30:46):
I have a question concerning freefall, as I understand it,
when you're in freefall, you don't move it all. Instead,
the Earth is ration to watch you. Now my question
is this. I live in Howder, which is in the
rest of the Netherlands. I have a nephew in Perth, Australia,
which is roughly the opposite side of the earth. Well,
we decided to jump out of an airplane on the
same time, which way is the earth moving? Thank you
(31:09):
very much for your answer.
Speaker 1 (31:10):
All right, so you know, maybe first we should start
with the disclaimer that you shouldn't do this unless you're
a professional. Have you ever done sky jumping or have
you ever jumped from a plane?
Speaker 2 (31:20):
I one time did skydiving. Yes, I jumped from an
airplane exactly one time. And I did it one time
because I did my homework and I looked up how
often people die skydiving, and it turns out it's very
very rare to die the first time you jump, and
it's very very rare to die after like ten jumps.
But there's a danger zone between like two and nine jumps.
(31:42):
And my understanding is that the first time you jump,
you're very careful, you're freaked out, you check all the straps,
you're like following all the safety videos, and when you
survive that first time, you're like, oh, maybe it's not
so dangerous. And then you get sloppy. And when you
get sloppy and you're like feeling confident, that's the danger zone.
Then and if you survive like nine or ten jumps,
you become really good at it, and then you're back
(32:04):
in the safe zone. So I did it once. I survived,
and I'm never doing it again.
Speaker 1 (32:09):
Wait, you controlled your own parachute and everything when you jumped.
Speaker 2 (32:11):
I got to pull my parachute, but it was a
tandem jump of strapped to another dude who was there
to like make sure I did it right.
Speaker 1 (32:16):
But yeah, when I did it, there was a dude
on my back. Okay, I mean, did you ask the
guy on your back is this your second to ninth jump?
That's the guy you need to ask. I think that's right.
Speaker 2 (32:27):
It might be his second and ninth jump that day.
I think these guys go up all the time.
Speaker 1 (32:31):
Yeah, yeah, I think so too.
Speaker 2 (32:33):
But it was sort of terrifying because they told us, hey,
you can change your mind at any moment. And the
friend I went with, she was standing at the edge
of the door ready to jump out, and she was like, yeah, no,
I can't do it, and they're like, no, you're doing it.
And she's like, you said I could change my mind,
and they're like, we were lying. Nobody changes their mind,
and then they pushed her out the door.
Speaker 1 (32:53):
I had brought a boyfriend who you know didn't end
up marrying, maybe not surprisingly after you hear this story
for his birthday. Oh and he got to the door
and he said, I don't want to do it. And
the guy strapped to his back looked at me, and
I said, and I pointed out, and the guy jumped.
And you know, my boyfriend was happy afterwards that he
did it, but he had also tried to back out
at the last second.
Speaker 2 (33:13):
So folks, when they tell you you can back out,
don't believe them if you don't want to jump, and
don't go up in the plane. Yeah, all right, but
today we are not giving advice about ways to risk
your life and get adrilline thrills. We're talking about understanding
the fundamental nature of gravity, how does it work? And Hans,
I think is responding to a conversation we had about
gravity and freefall and who's really accelerating, in which an
(33:36):
explanation I gave is that the Earth is accelerating up
and out towards you. You're not falling towards the Earth.
And so I think it's worthwhile to revisit that explanation
a little bit and then unpack it in the context
of Hans's question, All.
Speaker 1 (33:49):
Right, let's go for it. So if you jump out
of a plane, what does Newton say is happening?
Speaker 2 (33:54):
Yeah, So, from a Newton point of view, if you're
on the surface and you see somebody jump out of
an airplane, you say, is a force of gravity and
forces create acceleration. So gravity is accelerating you down towards
the surface. And that's Newton's explanation. And from the point
of view of the person on the surface, that makes
perfect sense because you see somebody's velocity and they're accelerating
because their velocity is changing, and so it looks perfectly
(34:16):
like there's a force there and the person is accelerating.
From the point of view of the jumper, right, they
jump out of the airplane, they see the surface of
the Earth rushing towards them. Right, they see Earth accelerating
towards them. Now, velocity is perfectly relative, right, And so
you might wonder, like, well, who's right, who is actually accelerating?
And this is where Einstein comes in, because Einstein tells
(34:39):
us that, like, velocity is relative, but acceleration is not.
So let's unpack what that means for a moment like
we say that distance is relative, like Kelly and I
are three thousand miles from each other right now. And
when we say distance is relative, we mean that you
have to measure it relative to somewhere else. Like I
can say I'm three thousand miles from Kelly. I can't
(35:01):
just say I am three thousand miles. That doesn't have
any meaning, right, I have to say what I'm three
thousand miles away from. Velocity is also relative. I can
say I have zero velocity right now relative to Kelly,
but I don't have zero velocity relative to the Sun.
And I don't have zero velocity relative to some particle
that's speeding towards the Earth at almost the speed of light.
(35:22):
In fact, I'm traveling at nearly the speed of light
relative to that particle, right And so velocity is only
defined relative to other stuff. And that's confusing because when
somebody jumps out an airplane, you wonder, like, well, are
they moving towards the Earth? Is the Earth moving towards them?
Both of those are perfectly valid. Because velocity is relative,
you can't say which one's actually moving. But now you
(35:44):
get to acceleration. Acceleration is different. Acceleration is not relative.
Velocity is relative. It's a property of a pair of objects,
me and Kelly, and me and the Earth, me and
the Sun. But acceleration is a property of an object.
I can tell if I'm accelerating. You can tell if
you're accelerating. How can you do that? Well, say, for example,
you're in a truck and you have a bowling ball
(36:05):
in the back of the truck. You can tell when
somebody hits the brake on the truck. You can tell
when somebody accelerates because the bowling ball in the back
of the truck will respond. What happens if you hit
the brakes, the bowling ball keeps going and will bang
into the front of the truck bed. And if you accelerate,
the bowling ball rolls backwards towards the back of the
truck bed. So you can measure your acceleration yourself. You
(36:27):
don't need to measure relative to the Sun or the
Earth or your podcast co host or anything like that.
So that means you can do something interesting. You can
ask like, well, is the guy who jumped out of
an airplane is he accelerating? Or is the guy on
the ground on the Earth are they accelerating because both
of them think the other one is accelerating. But Einstein says, no,
(36:48):
you can actually just measure it and you can tell
the answer.
Speaker 1 (36:51):
And the answer is that the person who jumped is accelerating.
Speaker 2 (36:54):
No, the answer is the person on the earth is accelerating. No, yes, absolutely.
Imagine you jump out an airplane and you're holding a
box with like a billiard ball in it. Right, what's
going to happen to that ball? You feel like you're
accelerating towards the surface of the Earth. But you look
at the ball. The ball is not moving inside the box.
The ball is going with you. It has exactly the
same experience you do. Now somebody on the surface of
(37:15):
the Earth, they have a ball in the box. That
ball is pulled towards the surface of the Earth. That's
measuring acceleration. Another way to do this is to have
a scale. So you jump out of an airplane with
a scale, and now you stand on the scale. Are
you going to measure anything? No, because there's nothing pushing
you onto the scale. Whereas if you put the scale
in the surface of the Earth and you stand on it,
(37:37):
you're going to measure your weight. Right, that weight is
actually measuring your acceleration. Einstein says, what's happening there is
the surface of the Earth and that scale are accelerating
up and out right. So a scale is like an accelerometer.
And so when you jump out of an airplane, you
can measure that you're not accelerating. You're in free fall.
(37:58):
There is no gravitational force on you, because there is
no gravitational force on the surface of the Earth. What
you're measuring is not the force of gravity. The weight
doesn't measure the force of gravity. It measures the acceleration
of the surface of the Earth up and out away
from the center of the Earth.
Speaker 1 (38:16):
That's counterintuitive, yeah, exactly, but it actually makes much more sense.
Speaker 2 (38:20):
The way to think about forces and acceleration and gravity
is to remember that there can be apparent forces like say,
for example, you have a merry go round and somebody
spins the merry go round. You feel this force pushing
you off the merry go round, right, But there's no
force there. There's nobody pushing on you. It feels like
there's a force. There's an apparent force what we call
(38:41):
in physics a pseudo force, because you're accelerating, because you're
rotating creates this pseudo force. So some things in the
universe can create these pseudo forces that make it seem
like there's a force when there isn't really one. And
that's what space does. That's what gravity is. Gravity isn't
a force. It's just that space is bent in certain ways,
(39:01):
and objects like to follow the curvature of that space. So,
for example, near a huge mass, space is bent and
objects like to follow the curvature of space, which brings
them towards the center of that mass. You jump out
of an airplane, space is curved there. Because you're near
the Earth and your natural motion is towards the surface
of the Earth, and you need acceleration. You need a
(39:24):
force to prevent you from moving in free fall, to
work against the motion of space and time. So I
understand Hans's question. Hans is like, hold on, you're saying
the Earth is accelerating. How can it be accelerating up
in the Netherlands and up from Perth? Right, it seems
like it's going in two directions. And that's because you're
thinking about the Earth as a single sphere moving in
(39:45):
one direction or moving in the other direction. Instead, imagine
it as a sphere with variable radius. Gravity is trying
to shrink the Earth down into a dot, and the
structure of the Earth is pushing back up and out
in every direction. So the answer is that it's accelera
up and out in the Netherlands and up and out
in Perth. Both are out away from the center. If
(40:06):
there wasn't that acceleration, if the whole Earth was just
a bunch of particles following the curvature of space time,
it would collapse into a black hole. That's what gravity
wants to do. It gathers stuff together because it bends space,
and then the motion of those particles follows that bend
space and things fall together. So Earth has to push
up and out just to maintain the same distance from
(40:28):
the center. So it's counterintuitive because now I'm saying you
have to accelerate just to maintain a constant distance from
the center of the Earth. That's very counterintuitive, but it's
true because their natural motion is to fall in towards
the center, and you have to accelerate, which means counter
your motion relative to gravity, to avoid doing that. So, yeah, Hans,
(40:49):
the Earth is accelerating up under you and up under
your nephew in Perth.
Speaker 1 (40:53):
Who does that make right? That's the important question.
Speaker 2 (40:58):
Let's just all sit down over a night, play the
meat honey and work it out.
Speaker 1 (41:02):
Oh no, let's never do that. Let's never ever do that,
or at least let's not be told that we're eating
meat honey if that's what we're having.
Speaker 2 (41:10):
All right. Well, I hope that cleared it up for Hans.
Let's send him o answer and see if he's got
some follow up questions.
Speaker 3 (41:16):
Hi, Daniel and Katie, thank you very much for your answer.
It was very enlightening. It still seemed somewhat counterintuitive to me,
but I believe I can now understand what you mean,
in particular the idea that you shouldn't see the Earth
as a solid object, but as a constant moving against
gravity to maintain the shape instantly. This reminds me of
(41:36):
Alison Wonderland. You have to run to stay in place.
I hope this makes any sense to you. Thank you
very much again, Hans.
Speaker 1 (41:43):
Well, thanks to everybody who submitted a question. Please, we
want more people to submit more questions, and if you've
got a question you want to share, you can send
it to us through our discord and you can find
the link to that on our website, or you can
send us an email at Questions at Daniel and Kelly
dot org.
Speaker 2 (42:00):
All right, and if you're still listening, we have one
more request for you. We want to know more about you,
not just what you're wondering in your questions about the universe.
We want to know who you are, what you listen to,
where you like to live, and what you do in
your spare time so we can get to know you
a little better. We have a survey for our listeners.
If you have a few minutes, we would love to
hear some more about you. You can find a link
to the survey on our website www dot danieland Kelly
(42:23):
dot org.
Speaker 1 (42:24):
Thanks everyone. Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio.
We would love to hear from you, We really would.
Speaker 2 (42:38):
We want to know what questions you have about this
Extraordinary Universe.
Speaker 1 (42:43):
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 (42:50):
We really mean it. We answer every message. Email us
at questions at Danielankelly.
Speaker 1 (42:55):
Dot 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 (43:05):
Don't be shy, write to us,
How do some bees make meat honey? What are tapeworms
up to in my tummy?
Speaker 2 (00:11):
Can light escape from a black hole? What process produces coal?
Speaker 1 (00:15):
Did Franklin hang that key from a kite? Why is
dark chocolate better than white?
Speaker 2 (00:20):
How do moles smell underwater? Why is the planet getting hotter?
Speaker 1 (00:24):
How can humans live on Mars? What's the hold up
with flying cars?
Speaker 2 (00:28):
The current state of space law? The powerful mantis, shrimp claw?
Speaker 1 (00:32):
Biology, physics, archaeology, forestry, really anything other than chemistry?
Speaker 2 (00:38):
What diseases do you get from your cat? Well, we'll
find the answers to all of that.
Speaker 1 (00:43):
Whatever question keeps you up at night.
Speaker 2 (00:45):
Daniel and Kelly's answer will make it right.
Speaker 1 (00:48):
Welcome to another Listener Questions episode on Daniel and Kelly's
Extraordinary Universe.
Speaker 3 (01:07):
Hi.
Speaker 2 (01:07):
I'm Daniel, I'm a particle physicist, and I've never read
a poem on the podcast before.
Speaker 4 (01:12):
Hi.
Speaker 1 (01:13):
I'm Kelly Wiener Smith. And my husband just assumed that
I'd be so bad at writing poems that when I
read it out loud to my daughter, he left the
room just so that he wouldn't be embarrassed. But you
know what, I had fun.
Speaker 2 (01:25):
I hope he's blushing somewhere. Whenever he's listening to this, he.
Speaker 1 (01:28):
Might skip all of our Listener Questions episodes from here
on out. But that's all right. I had a good time.
Speaker 2 (01:33):
Well that's too bad, because those are my favorite episodes.
I love hearing what people are wondering about, helping them
unravel their confusion and getting to the topics that are
really in people's minds. It's my favorite way to interact
with our audience.
Speaker 1 (01:47):
I love it as well, and I'm particularly excited about
this Listener Questions episode. You know, one because my daughter's
questions included and that's pretty cute. But two because we
got a biology question for me that I was she
is completely unaware of this group of species and they're
so creepy and right up my alley and it was
so much fun.
Speaker 2 (02:06):
All right, Well, let's not waste any more time. Let's
dig into it today. We have questions about seasons on
Binary Star systems, about meat, wasp honey, and about how
gravity actually works.
Speaker 1 (02:19):
Let's do it.
Speaker 2 (02:19):
So our first question is from Aida. She's ten years
old and she lives in Virginia, and I think she
knows Kelly pretty well.
Speaker 1 (02:26):
Great place to live, I'll just throw that in there.
Speaker 2 (02:30):
Here's Ada's question.
Speaker 5 (02:32):
Hi. I'm Ada, I'm ten years old. I have a
question for you. What would seasons be like if you
were on a planet in a solar system that had
two sons? Thank you?
Speaker 2 (02:43):
All right? I like how she gets right to the point.
Speaker 1 (02:46):
Yes, she's very succinct. I like that too.
Speaker 2 (02:48):
Is she reading a book about life on a solar
system with two sons? Or where do you think this
question came from?
Speaker 1 (02:54):
Gosh, you know, I'm sure it didn't come out of nowhere,
but I don't know where she heard about solarsis with
two suns. That sparkedness. Could have been science class at school.
Speaker 2 (03:03):
Maybe she's writing a science fiction novel and she needs
some science consultation.
Speaker 1 (03:08):
That's right, Yes, and she reached out to the right person.
Speaker 2 (03:10):
Yeh, she certainly did. So let's dig into it first.
Let's remind ourselves why we have seasons on Earth, and
then we can teleport ourselves mentally to a solar system
with two stars and think about that one. So, on Earth,
the reason we have seasons is because the Earth is
tilted right. The Earth goes around the Sun, and there's
a plane there where all the planets go around the
(03:32):
Sun in the same plane, and the Earth also spins,
but the axis that it spins on is not perfectly
perpendicular to the plane of its orbit, so it's tilted
a little bit. It like leans over. Now, the Earth
is a sphere, so you know what is really leaning.
It's still a sphere when it's tilted. But what's leaning
is that axis of spin, that axis that controls the
(03:53):
day night cycle. So what's closer to the Sun is
the Northern hemisphere the spin lets you define a northern
and the southern hemisphere, Then the Northern hemisphere is closer
to the Sun during the summer, and the Southern hemisphere
is further from the Sun during the Northern hemisphere summer
and the Southern hemisphere's winter. It's not actually accurate to
say that the Northern hemisphere is any closer to the Sun.
(04:14):
Is just more exposed to the Sun because it's leaning
that direction, got it?
Speaker 1 (04:18):
And you know, I've got to admit that every once
in a while, when I talk to like the few
friends I have in Australia, I still forget that they're
experiencing the opposite season that we are up here in
North America. And we regularly have a disconnect.
Speaker 2 (04:31):
Yeah, exactly. And so if we didn't have a tilt.
For example, if the Earth's axis of rotation was perfectly
perpendicular to the plane of its orbit, then you wouldn't
have any seasons. You just always have I guess spring
or fall. Right, the days would be the same length
all year round. Going around the Sun wouldn't change your
experience at all.
Speaker 1 (04:51):
No seasons, totally boring, just like living in California. You
knew where that was going halfway through the sentence.
Speaker 2 (05:00):
Exactly, we'd all be happy all year long, right, it'd
be amazing, so dull. And there are other tiny factors
that also affect the weather and the seasons, things like
the elliptical orbit, or the Earth doesn't orbit in a
perfect circle around the Sun. It's an ellipse, which means
sometimes it is closer to the Sun and sometimes it's
further from the Sun. But this is a smaller factor
(05:23):
than the tilt, which really dramatically changes how many hours
of sunlight you get every day. The Earth is closest
to the Sun in January and furthest from the Sun
in July, so actually that counters the effect. It makes
the summer slightly less severe and the winter's slightly less severe.
Speaker 1 (05:39):
Is that why the year starts in January? Or did
that have nothing to do with the calend No.
Speaker 2 (05:45):
That's totally random. Yeah, Oka's totally right. And also the
Earth tilt processes a little bit. It's not always in
the same direction. It itself rotates a little bit, like
a wobbly top. These are small factors, and that's affected
by like the Jupiter and all sorts of other stuff.
So mostly the Earth has seasons because it's tilted, So
the northern hemisphere is getting more light and the southern
(06:07):
hemisphere is getting less light during the northern hemisphere summer.
All right, but that's a simple system, single planet going
around a single star. So what about a binary star
system in Ada's mind?
Speaker 1 (06:18):
Can I back you up for a second? Are most
planets tilted so like the Moon has a very little
bit of a tilt. Is Earth weird having a twenty
three point four degree tilt?
Speaker 2 (06:27):
It's not weird to have a tilt like Urinus is
tilted much more dramatically ninety seven degrees, basically totally on
its side. Other planets are tilted more or less. The
tilt we think comes from being hit. Like everything in
the Solar System formed together from a big swirl. That's
why everything is rotating in the same plane, and most
of the planets are spinning in the same direction they
(06:48):
move around the Sun, which is the same direction that
the Sun is spinning itself. The whole Solar system is
one big swirl, which then coalesces into a star and
planets which all have the same swirl. But then you
can get hit by something from outside the Solar system
and it can knock you off axis a little bit.
So we think that's probably the source of the Earth's tilt,
and other planets tilt as well.
Speaker 1 (07:09):
With all the stuff that's colliding, Would it be reasonable
to expect that having no tilt would be rare because
there's so many collisions that probably knock you off angle.
Speaker 2 (07:17):
Yeah, As the Solar system forms, it's a little chaotic
and things hit each other, so the average tilt is
going to be zero, but it's unlikely for everything to
have exactly zero tilt. Got it just the same with it,
Like all the solar systems in the galaxy on average
have zero tilt relative to the plane of the galaxy,
but most of them are tilted relative to the plane
of the galaxy. They're not all aligned with the actual
(07:39):
rotation of the galaxy.
Speaker 1 (07:40):
All right, So let's move on to systems with two sons.
Speaker 2 (07:43):
All right. So system with two sons sound exotic, right,
You're like, ooh wow, two sons, how cool, But the
truth is that they're not actually that rare. Binary star
systems are all over the galaxy. It's a significant fraction
of the stars in our galaxy have a partner star.
And the reason is that that big cloud of gas
that collapses to give you a star usually it's part
(08:04):
of a much bigger cloud. So stars are born together.
Often you have two, three, four, five stars all born together,
which begin a complicated swirl as they're forming. So you
have these nurseries. We have a lot of star forming
happening at the same time, and so stars are born
with partners. And the reason we have a lot of
binary star systems is that it's basically the most number
(08:26):
of stars you can have in a system and have
it be stable. Like you can have two things orbiting
each other and have that be stable, like the Earth
and the Sun or a star and another star. But
you add a third object and it becomes chaotic, it
becomes really complicated and unstable. So if you have three stars,
for example, what's very likely to happen is one of
them is going to get ejected and you're going to
(08:48):
end up with a single star and then a pair
of stars. So you have a lot of binary star
systems out there, not very many trinary systems or quaternary systems,
or not even know the descriptions for five or more stars.
Speaker 1 (09:01):
So why is it more likely to get ejected than
to get pulled into one of the other two stars
and then just make like, I don't know, a big star,
a big explosion.
Speaker 2 (09:10):
Yeah, well that could happen also, but you know, stars
are small compared to the distances between them, and so
actual collisions are pretty unlikely, but they can spiral in
and combine. That certainly does happen as well, But there's
just many more outcomes where they get ejected, and just
like in our Solar system, there's been chaos. We think
probably there was another giant planet which got ejected from
(09:31):
the Solar System because of the interaction between all the planets.
So you have a lot of binary star systems out there,
and then you have to think about the planets around
those binary stars, and it becomes tricky already because now
the planet is sort of like that third object. So
you might wonder like, hey, isn't the planet just going
to get ejected the way like a third star would
get ejected, And the answer is yes, it's not easy
(09:52):
to have planets around binary stars in a stable way.
There's two ways to do it, and both of them
basically make it look more like a binary star system.
So one solution is you have the two stars near
each other and the planet is far away, so it's
sort of like, yeah, there are three objects there, but
really it's sort of a nested set of binary systems.
You have like the stars on one side and the
(10:14):
planet that are orbiting each other, and then inside the
sort of star system, you have two stars moving near
each other. That's one situation, basically, like replace the Sun
with two stars close to each other or closer to
each other than to the planet. The other possible configuration
is you have a star and a planet like the
Earth and the Sun, and then you have another star
that's much further away, so like put a star near
(10:36):
Pluto or something much further from the Earth than the
Sun and then it's far enough away that it's not unstable.
Then you have like again a nested set of binary systems.
You have three objects, but really it's like two objects
acting as one and then in a binary system with
the third object.
Speaker 1 (10:54):
Okay, so then let's talk about seasons. In the first
scen area, where you have two stars that are right
next to each other, do they act like one just
megastar when you sort of aggregate their effects.
Speaker 2 (11:05):
Yeah, they act like one megastar. It's going to be
very similar to as if you had one bigger star.
It's going to be different and more dramatic in terms
of like sunrise and sunset. Sunrise will be longer and
sunset will be longer, and there'll be times when you
have like one star above the horizon and one below,
so you could have effects like you could have a
sunrise where there's already a star in the sky, and
(11:27):
then you have basically two sunsets, one more dramatic than
the next. So that would be really cool, but it
wouldn't really affect the seasons very much, right because the
planet's relationship to the star is basically the same. If
you have a tilt and you have an orbit that's
going to determine your seasons. So in that situation where
you have a planet around a binary star system where
the stars are close to each other and further from
(11:48):
the planet, the seasons are going to be very much
like here on Earth.
Speaker 1 (11:51):
I feel like it would be amazing to wake up
to a sunrise with two stars in the horizon. That
sounds really cool. But all right, So then our second scenario,
you say, there's one sun that's kind of close to
the planet and another sun that's super far out. Is
it far enough out that it doesn't really impact climates
and seasons anymore?
Speaker 2 (12:11):
Unfortunately? Yeah, So the boring answer is for there to
be a planet in this situation, that star has to
be kind of far away. The closer you get it,
the more dramatic and the impact on seasons and day
night stuff, etc. But also the more unstable it is. Like,
if you have the planet be the same distance from
both stars, so it's like very dramatic, then that system
is totally unstable and it's not gonna last for very long.
(12:34):
So you got to push that second star kind of
far away, which means really it's gonna be in the
sky more like a bright star. Than a real sun
and not really gonna affect your seasons. You're gonna have
one totally dominant star and then a second star that's
gonna sometimes make the night a little brighter or even
the day a little brighter, but it's not gonna have
(12:54):
that much effect. But you know, in a science fiction
sort of inspiration, we can move that second star in
as as much as possible and pretend that it does
have some impact because there's some crazy dynamics that happen
in that scenario.
Speaker 1 (13:07):
Okay, let's go for it. What is that like super winter?
Speaker 2 (13:12):
Yeah, exactly. If you think about the periods when you
have sunlight, that really is what determines the seasons. Right
in a single star, single planet system, it's the number
of hours per day of sunlight you get that determine
the seasons. And in the summer you're getting more sun.
In the winter, you're getting less sun. Now put that
second star around, say we have the second star, you know,
in Mars orbit or something crazy, then you're going to
(13:35):
be getting sunlight all sorts of weird configurations, like there
can be parts of the year where each star is
illuminating a different side of the planet. Put the planet
between the two stars. Right, they're all in a line.
You have star, planet Star, then every part of the
surface is seeing a star. Right, It's like the whole
world has noon at the same time, right, which would
(13:56):
be crazy. So you have periods where the whole planet
is seeing star, and then other scenarios where like in
a line it goes star star planet where half of
the planet is seeing both stars at the same time,
and if they're both pretty close, that's gonna be superday.
That's like super noon, right, and that's gonna be very intense,
super duper hot. And also you'll get a weird effect
(14:19):
there where potentially the stars eclipse each other. So like
you know, we have solar eclipses and lunar eclipses, this
would be like a stellar eclipse where one sun is
behind the other sun briefly. That would be awesome.
Speaker 1 (14:31):
Don't look at either.
Speaker 2 (14:36):
But I actually looked up a simulator to try to
figure out exactly what would happen through the year, and
it depends crucially on the orbit of that second star.
If that second star has a period of about a year,
like the same as the planet's orbit, then you're gonna
have a regular cycle. But you're gonna have times in
the year where even at the equator you have no darkness,
like you see one sun and the planet spins and
(14:57):
you see the other sun. And so that's going to
be very summary, right, because it's all about the hours
of sunlight you get and other parts of the year
where you're seeing both suns at the same time, so
you're getting fewer hours of daylight, but they're more intense,
they're brighter. So you're gonna have these really weird periods.
I don't know how the plants would respond to that,
or how you would evolve in that kind of.
Speaker 1 (15:18):
Configuration circadian rhythms, mm hmm.
Speaker 2 (15:21):
It's gonna be a total mess, but it would be regular,
you know. And if, for example, the second star has
a longer period, it takes longer to go around that
first star and the planet, then its affects can slide
through the year, right, It's not like every June we
have double sun, every January we have one sun. It
can slowly offset and that must really affect like the
(15:43):
development of a civilization, you know, because we use the
regular seasons, and the regular day night cycle really is
a way to tell time. So either you have to
have much more complex mathematics before you can even begin
to use a calendar and develop it. Or maybe you
get some art or quicker because the calendar is more
complicated and it inspires more interesting mathematics. But the short
(16:03):
answer is that the seasons are going to be intense
and complicated, and it depends on a lot of the details,
exactly how fast that second star goes around the first star.
Speaker 1 (16:12):
I wonder if it would hinder the establishment of civilizations,
because like being able to plan things like when you
plant your crops seems really important. I wonder if we'd
all be like wanderers because planning just isn't worth even trying,
but really fun to think about it. You know, there's
got to be a couple of sci fi novels in.
Speaker 2 (16:27):
There, Yeah, exactly. And you know there's the famous book
The three Body Problem, where they have essentially this question,
except it's actually the four body problem because they have
three stars and a planet. I don't know why they
like couldn't figure out how to count to three. It's
already complicated enough with two stars. You don't need a
third star.
Speaker 1 (16:47):
Yeah. Well, when Ada's done with her math homework, will
have her listen to this explanation and hear what she
had to say.
Speaker 2 (16:56):
Maybe we should have her on in real time for
a follow up. Let's do it, hi Ada, thanks very
much for your question. I was curious what you thought
about our answer and if you have any follow up questions.
Speaker 5 (17:10):
I understood like what I heard when I listened to
the podcast, m H. And I do have one follow
up question.
Speaker 2 (17:25):
Oh goodie, what is it?
Speaker 6 (17:26):
So?
Speaker 5 (17:28):
Was our sun in this our source system like part
of a different source system and then was it ejected
out or was it just not like that?
Speaker 2 (17:45):
Yeah, that's a great question. Unfortunately we don't know the answer.
Most stars are born with other stars nearby. There's like
sibling stars sometimes two, three, five, seven, as part of
a big nursery, and then they're separated, as you know,
gravity lings them around. But we don't know the history
of our star that far back, so probably it was
(18:05):
born with other stars, but we don't actually know. Maybe
one day we'll figure out some way to figure it out,
but for now we don't know the answer. Thank you,
thanks so much for your question.
Speaker 1 (18:32):
All right, so now for something absolutely totally different, we
have a fantastic question from listener James Palmer, and it
is a question about meat bees otherwise known as vulture bees,
which I had not heard of, but is absolutely right
up my alley. So let's hear the question.
Speaker 4 (18:50):
Hey, Kelly and Daniel, I have a burning desire to
know everything about meat wasps. I just heard about them,
and I feel like there's a lot to discuss here,
Like apparently they are carnivorous and the eat on like
flesh and like maybe it's rotting. Then they use that
to make their honey and stuff like meat honey. Please
tell me everything.
Speaker 1 (19:12):
Meat honey, Daniel. You're dying to know about meat honey.
Speaker 4 (19:16):
Right.
Speaker 2 (19:16):
Well, you know, we have lots of different kinds of
honey here in California, and often it's sold to us
by promoting the kind of flowers that the bees visit,
like ooh, this is lavender honey or wildflower honey, and
you're supposed to imagine that you can taste the lavender
as you're eating the honey. And so I'm wondering, now,
meat bee honey, is it gonna taste like pepperoni or
what's going on?
Speaker 1 (19:36):
Oh gosh, you know, to be honest, I would never
try it. But there's not a lot of honey that
is meat honey. So there's a lot of bees that
make something called honey, but there's only three species that
do this meat honey thing exclusively. So I think maybe
we should start with how honey is made. Yea, because
I actually didn't understand this very well.
Speaker 2 (19:57):
I have this naive understanding that like bee eat pollen
and then do something internally and then vomit up honey.
How wrong is that?
Speaker 1 (20:04):
Yeah? I thought that too, Okay, totally, like almost one
hundred percent. Okay, so that was my thought too. Okay,
So let's start with the European honey bees as an example. Okay,
So this is APIs Melfera, and what they do is
they go out and they go to flowers, and the
flowers produce both nectar, which is like sugar water, and pollen,
which has a lot of protein. And so these fill
(20:25):
two very different rolls for the bees. So they get
their carbohydrates from the nectar, okay, and that's gonna become honey,
and then the pollen is their protein source. And sometimes
the pollen like gets in the honey. It almost sounds
like it's accidental, but mostly the honey is from the nectar.
Not from the pollen, but.
Speaker 2 (20:44):
The bees also eat the pollen. I thought the pollen
was incidental and going along for a ride, and it
was part of the plants deal with the bees, Like
you can eat the nectar, but then I'm gonna get
the pollen all over you and you're gonna drop it
on another flower and help us reproduce.
Speaker 1 (20:57):
No, they eat it too. Oh no, they eat it
and they feed it to like the baby bees, and
so it's like a very important protein source. I didn't
know that either. And actually there's four different kinds of bees.
There's the honey bees, the orchid bees, the bumblebees, and
the stingless bees. And they're all categorized by having what
are called corbicula and these are like chunky thighs with
(21:19):
like a way to like stick the pollen on there.
And so like I saw a bee on one of
our flowers the other day and I was like, what
is this orange? Like it's like they've got bling on
their hips. I know, as an ecologist, I should have
been like mortified that I didn't know what this was already.
But anyway, those are like four carrying pollen around so
they can bring it back to the.
Speaker 2 (21:37):
Hive, I see, And so do the plants get anything
out of it? I thought bees were pollinators.
Speaker 1 (21:42):
Yeah, I think some of it still like falls off
and lands in the right place, so the pollination still happens.
But the bees aren't moving the pollen around as a favor.
It's more like incidental. So that's how nature. No one
helps anyone out in nature unless they have to, all right.
Speaker 2 (21:57):
So bees drink pollen and then they use that to
make the honey. How do they actually make the honeyes
that inside the bee? Or is that in one of
their little hexagonal cooking vats.
Speaker 1 (22:07):
Bees drink nectar. They don't drink the pollen.
Speaker 2 (22:10):
Oh sorry, right, yes, okay.
Speaker 1 (22:11):
That's okay. Or they sometimes drink a honeydew, which is
this like sweet fluid produced by insects as like a
way to attract organisms that like protect them from natural enemies.
They collect it in this special organ where they collect
all of this sugary water, and you know, they can
use it a little bit for like their flight to
get from place to place, but they're you know, trying
(22:31):
to bring it back to the hive. So they fill
up this organ and I think that something like half
of their body weight can end up being this sugary water.
But the sugary water is nowhere near concentrated enough to
be honey. So what they do is they bring it
back to the hive and they regurgitate it to bees
whose job it is to try to get some of
the water out and concentrate the sugars more. And so
(22:55):
those bees they like start kind of partially regurgitating it
and blowing these like bubbles that increase the surface area,
so some of the water evaporates off it.
Speaker 2 (23:04):
Didn't know that the physics of honey look at that, Yes, right, And.
Speaker 1 (23:08):
I hadn't imagined that so much of honey involved vomit.
But there you go, so much fun hanging out with biologists.
Speaker 2 (23:16):
When I'm vomiting, I'm not busy also trying to concentrate
it and evaporate it. So I have like gooey or vomit.
I guess that's what a bee does.
Speaker 1 (23:24):
I mean, you're not so great at multitasking. Too bad.
Speaker 2 (23:28):
I'll work on that. I'll work on that. You know,
good to have goals. Yeah, all right, So bees vomit
up the nectar, and then other specialized bees help evaporate
and concentrate it into honey. So that mean that honey
is just nectar that's been concentrated down or is there
some fermentation that also happens.
Speaker 1 (23:44):
That's just one of the stages of evaporation that gets
a little bit of the water out, and then when
they store it in the combs, like the you know,
honey combs, I'm under the impression that some more evaporation
happens there. So bees produce a little bit of heat
by like, you know, shaking their wings really fast. That
also produces some airflow over the honeycombs, and that combination
of heat and then air moving throughout the colony and
(24:07):
then sort of back out of the hive, that finishes
evaporating off the water until you get to a point
where you've got enough concentrated sugar that you've got honey.
Speaker 2 (24:15):
Wow. Fascinating.
Speaker 1 (24:17):
Yeah, I didn't know any of that. That was awesome.
Speaker 2 (24:19):
So then it makes sense that if I'm eating the
honey from bees that visited lavender, it shit tastes like
lavender because it really is like concentrated lavender nectar.
Speaker 1 (24:27):
If lavender nectar smells like lavender, I don't know that
it does. And I'm one of those people who has
had honey from different places and been like, it's all
honey to me. I don't have a delicate paletate.
Speaker 2 (24:39):
Okay, So now tell us about meat wasps. Where do
they get their supplies to make honey?
Speaker 1 (24:45):
Okay?
Speaker 2 (24:45):
So I'm terrified of this answer, by the way.
Speaker 1 (24:48):
Yeah, all right. So the best honeymakers are the European
honey bees, the best in terms of like producing honey
that humans like, but a bunch of other kinds of
bees they make similar honey, but often their honey is
nowhere near as like concentrated with sugars. It's more watery.
And there's a group of bees called the stingless bees,
and now we're getting closer to the vulture bees. So
the stingless bees they make honey, but their honey tends
(25:11):
to be more watery, and instead of storing it in
those combs, they make these little waxy pots, and it's
harder to get it out of those waxy pots, and
it's like more watered down when you do. So people
did still keep these bees for sugary fluids, but as
soon as honey bees came along, a lot of the
stingless bees that do this more watered down, harder to
(25:32):
get honey, they became less popular to culture. But so
these stingless bees, they also get their nectar from flowers,
but there's a group in the genus Trigona where they
seem like they're less interested in flowers. So instead of
going to flowers for nectar, they get their sugars from
things like rotting fruits. They'll like take the sugars from that.
(25:56):
And instead of getting pollen, they get their protein from
dead animals, dead vertebrates in particular.
Speaker 2 (26:04):
I see. So that's why they're called vulture bees, because
vultures are scavengers. They don't kill anything. They eat already
dead stuff. So these vulture bees will get their protein
not from pollen, but from dead animals.
Speaker 1 (26:13):
You're saying, that's right. And they'll get their sugar, which
they used, you know, like make their honey stuff. They
get that from things like writing fruit are free they find, Okay,
So then the question is do they make meat honey?
This is important and the answer I think is maybe.
Speaker 6 (26:31):
Oh.
Speaker 2 (26:32):
Really.
Speaker 1 (26:32):
So there's only three species of these vulture bees, and
they're all in the same genus, they're all closely related.
It does turn out that there's a fair number of
stingless bees that where like, if meat is left out,
they'll go ahead and get some protein from it, but
they're not required to get protein from it, so they're
called facultatively necrophagic, which means they'll like eat dead stuff
when they've got the chance, but they don't have to.
(26:54):
But these vulture bees are obligately necrophagic, so they have
to eat dead stuff. And currently they're really good at it,
Like they've got ways to sort of attract other members
to come so that they can like very quickly with
these specialized mouth parts scrape a bunch of like rotting flesh.
Oh my god, yeah, your face is like priceless.
Speaker 2 (27:12):
It should be called nightmare bees. Yikes.
Speaker 1 (27:15):
Yes, it's intense pretty metals. So then it's a little
bit unclear what happens. So I found a nineteen eighty
two paper that described what they were doing, and it
said the bees masticate and consume flesh at the feeding site.
They do not carry pieces of flesh to the nest,
but appear to hydrolyze it with a secretion produced by
(27:36):
either mandibular or salivary glands, which gives the feeding site
a wet appearance. Side note iw.
Speaker 2 (27:44):
That means they're slabbering right their slabberry and they have
meat slabber.
Speaker 1 (27:47):
They've got meat slabber, and their saliva is starting the
process of breaking down the meat. That's what that means.
And that says individual bees captured well feeding, then forced
to expel the contents of their crop. So essentially they
made these meat bees. Through up, we're carrying a slurry
of flesh measuring between thirty seven and sixty five percent
dissolved solids by volume.
Speaker 2 (28:07):
So a slurry of flesh. Isn't that like a nine
Inch Nails album title or something.
Speaker 1 (28:14):
I feel like we have to get in touch with
prent Resnor now and find some way to convey this
to him.
Speaker 2 (28:19):
Oh boy wow.
Speaker 1 (28:21):
And so then the question is how do they store
it when they get back. So I've read this paper
from twenty twenty one and they were laying out some
different hypotheses for what happens. It looks like that meat
slurry gets stored in pots. Maybe it gets mixed with
some of the sugary stuff they collect. I think at
the end of the day, it's not really clear what
they do how it's stored how long it's stored, but
you probably could say they make something called meat honey,
(28:43):
like they're taking that flesh slurry, they're storing it in
these pots. It looks like it quote unquote matures for
about two weeks into a paste that is also a
little bit sugary. So they do appear to be making
something like meat honey. Let's go for it. Looks like
part of this process and if your wife we're here,
(29:03):
maybe she'd be excited about this part. Part of it
appears to involve the microbiome. So these vulture bees have
microbiomes that include acidophilic bacteria, so bacteria that do really
well in acidic environments. And you find similar categories of bacteria,
they're not the exact same species, similar categories of bacteria
(29:23):
in the guts of like vultures. So it seems like
there's some kinds of bacteria that team up with organisms
that eat dead flesh to sort of help process it
and maybe also help make it safer, because bacteria that
get to the flesh first start producing like toxins maybe
to ward off these competitors, and these acid loving bacteria
sort of help make it all happen, and your face
is just priceless.
Speaker 2 (29:44):
Right now, I'm so glad I don't eat breakfast because
I'd be throwing it up into breakfast slurry right now,
and some bees could come along and make breakfast.
Speaker 1 (29:52):
Honey, meat honey, and so James, I have to thank you.
I had never heard of these before. And let's go
ahead and hear if you learned everything you wanted to
know about meat honey, and.
Speaker 2 (30:06):
If you're ever gonna eat honey again.
Speaker 6 (30:09):
I think it's safe to say that you taught me
everything I asked for and a lot more. So thanks
ver so much for that, guys. I appreciate it.
Speaker 2 (30:31):
All right. Our last question comes from Hans in the
Netherlands who has a nephew in Perth, and they've been
disagreeing about which direction the Earth is accelerating and how
gravity actually works. Let's hear the question from Hans.
Speaker 3 (30:46):
I have a question concerning freefall, as I understand it,
when you're in freefall, you don't move it all. Instead,
the Earth is ration to watch you. Now my question
is this. I live in Howder, which is in the
rest of the Netherlands. I have a nephew in Perth, Australia,
which is roughly the opposite side of the earth. Well,
we decided to jump out of an airplane on the
same time, which way is the earth moving? Thank you
(31:09):
very much for your answer.
Speaker 1 (31:10):
All right, so you know, maybe first we should start
with the disclaimer that you shouldn't do this unless you're
a professional. Have you ever done sky jumping or have
you ever jumped from a plane?
Speaker 2 (31:20):
I one time did skydiving. Yes, I jumped from an
airplane exactly one time. And I did it one time
because I did my homework and I looked up how
often people die skydiving, and it turns out it's very
very rare to die the first time you jump, and
it's very very rare to die after like ten jumps.
But there's a danger zone between like two and nine jumps.
(31:42):
And my understanding is that the first time you jump,
you're very careful, you're freaked out, you check all the straps,
you're like following all the safety videos, and when you
survive that first time, you're like, oh, maybe it's not
so dangerous. And then you get sloppy. And when you
get sloppy and you're like feeling confident, that's the danger zone.
Then and if you survive like nine or ten jumps,
you become really good at it, and then you're back
(32:04):
in the safe zone. So I did it once. I survived,
and I'm never doing it again.
Speaker 1 (32:09):
Wait, you controlled your own parachute and everything when you jumped.
Speaker 2 (32:11):
I got to pull my parachute, but it was a
tandem jump of strapped to another dude who was there
to like make sure I did it right.
Speaker 1 (32:16):
But yeah, when I did it, there was a dude
on my back. Okay, I mean, did you ask the
guy on your back is this your second to ninth jump?
That's the guy you need to ask. I think that's right.
Speaker 2 (32:27):
It might be his second and ninth jump that day.
I think these guys go up all the time.
Speaker 1 (32:31):
Yeah, yeah, I think so too.
Speaker 2 (32:33):
But it was sort of terrifying because they told us, hey,
you can change your mind at any moment. And the
friend I went with, she was standing at the edge
of the door ready to jump out, and she was like, yeah, no,
I can't do it, and they're like, no, you're doing it.
And she's like, you said I could change my mind,
and they're like, we were lying. Nobody changes their mind,
and then they pushed her out the door.
Speaker 1 (32:53):
I had brought a boyfriend who you know didn't end
up marrying, maybe not surprisingly after you hear this story
for his birthday. Oh and he got to the door
and he said, I don't want to do it. And
the guy strapped to his back looked at me, and
I said, and I pointed out, and the guy jumped.
And you know, my boyfriend was happy afterwards that he
did it, but he had also tried to back out
at the last second.
Speaker 2 (33:13):
So folks, when they tell you you can back out,
don't believe them if you don't want to jump, and
don't go up in the plane. Yeah, all right, but
today we are not giving advice about ways to risk
your life and get adrilline thrills. We're talking about understanding
the fundamental nature of gravity, how does it work? And Hans,
I think is responding to a conversation we had about
gravity and freefall and who's really accelerating, in which an
(33:36):
explanation I gave is that the Earth is accelerating up
and out towards you. You're not falling towards the Earth.
And so I think it's worthwhile to revisit that explanation
a little bit and then unpack it in the context
of Hans's question, All.
Speaker 1 (33:49):
Right, let's go for it. So if you jump out
of a plane, what does Newton say is happening?
Speaker 2 (33:54):
Yeah, So, from a Newton point of view, if you're
on the surface and you see somebody jump out of
an airplane, you say, is a force of gravity and
forces create acceleration. So gravity is accelerating you down towards
the surface. And that's Newton's explanation. And from the point
of view of the person on the surface, that makes
perfect sense because you see somebody's velocity and they're accelerating
because their velocity is changing, and so it looks perfectly
(34:16):
like there's a force there and the person is accelerating.
From the point of view of the jumper, right, they
jump out of the airplane, they see the surface of
the Earth rushing towards them. Right, they see Earth accelerating
towards them. Now, velocity is perfectly relative, right, And so
you might wonder, like, well, who's right, who is actually accelerating?
And this is where Einstein comes in, because Einstein tells
(34:39):
us that, like, velocity is relative, but acceleration is not.
So let's unpack what that means for a moment like
we say that distance is relative, like Kelly and I
are three thousand miles from each other right now. And
when we say distance is relative, we mean that you
have to measure it relative to somewhere else. Like I
can say I'm three thousand miles from Kelly. I can't
(35:01):
just say I am three thousand miles. That doesn't have
any meaning, right, I have to say what I'm three
thousand miles away from. Velocity is also relative. I can
say I have zero velocity right now relative to Kelly,
but I don't have zero velocity relative to the Sun.
And I don't have zero velocity relative to some particle
that's speeding towards the Earth at almost the speed of light.
(35:22):
In fact, I'm traveling at nearly the speed of light
relative to that particle, right And so velocity is only
defined relative to other stuff. And that's confusing because when
somebody jumps out an airplane, you wonder, like, well, are
they moving towards the Earth? Is the Earth moving towards them?
Both of those are perfectly valid. Because velocity is relative,
you can't say which one's actually moving. But now you
(35:44):
get to acceleration. Acceleration is different. Acceleration is not relative.
Velocity is relative. It's a property of a pair of objects,
me and Kelly, and me and the Earth, me and
the Sun. But acceleration is a property of an object.
I can tell if I'm accelerating. You can tell if
you're accelerating. How can you do that? Well, say, for example,
you're in a truck and you have a bowling ball
(36:05):
in the back of the truck. You can tell when
somebody hits the brake on the truck. You can tell
when somebody accelerates because the bowling ball in the back
of the truck will respond. What happens if you hit
the brakes, the bowling ball keeps going and will bang
into the front of the truck bed. And if you accelerate,
the bowling ball rolls backwards towards the back of the
truck bed. So you can measure your acceleration yourself. You
(36:27):
don't need to measure relative to the Sun or the
Earth or your podcast co host or anything like that.
So that means you can do something interesting. You can
ask like, well, is the guy who jumped out of
an airplane is he accelerating? Or is the guy on
the ground on the Earth are they accelerating because both
of them think the other one is accelerating. But Einstein says, no,
(36:48):
you can actually just measure it and you can tell
the answer.
Speaker 1 (36:51):
And the answer is that the person who jumped is accelerating.
Speaker 2 (36:54):
No, the answer is the person on the earth is accelerating. No, yes, absolutely.
Imagine you jump out an airplane and you're holding a
box with like a billiard ball in it. Right, what's
going to happen to that ball? You feel like you're
accelerating towards the surface of the Earth. But you look
at the ball. The ball is not moving inside the box.
The ball is going with you. It has exactly the
same experience you do. Now somebody on the surface of
(37:15):
the Earth, they have a ball in the box. That
ball is pulled towards the surface of the Earth. That's
measuring acceleration. Another way to do this is to have
a scale. So you jump out of an airplane with
a scale, and now you stand on the scale. Are
you going to measure anything? No, because there's nothing pushing
you onto the scale. Whereas if you put the scale
in the surface of the Earth and you stand on it,
(37:37):
you're going to measure your weight. Right, that weight is
actually measuring your acceleration. Einstein says, what's happening there is
the surface of the Earth and that scale are accelerating
up and out right. So a scale is like an accelerometer.
And so when you jump out of an airplane, you
can measure that you're not accelerating. You're in free fall.
(37:58):
There is no gravitational force on you, because there is
no gravitational force on the surface of the Earth. What
you're measuring is not the force of gravity. The weight
doesn't measure the force of gravity. It measures the acceleration
of the surface of the Earth up and out away
from the center of the Earth.
Speaker 1 (38:16):
That's counterintuitive, yeah, exactly, but it actually makes much more sense.
Speaker 2 (38:20):
The way to think about forces and acceleration and gravity
is to remember that there can be apparent forces like say,
for example, you have a merry go round and somebody
spins the merry go round. You feel this force pushing
you off the merry go round, right, But there's no
force there. There's nobody pushing on you. It feels like
there's a force. There's an apparent force what we call
(38:41):
in physics a pseudo force, because you're accelerating, because you're
rotating creates this pseudo force. So some things in the
universe can create these pseudo forces that make it seem
like there's a force when there isn't really one. And
that's what space does. That's what gravity is. Gravity isn't
a force. It's just that space is bent in certain ways,
(39:01):
and objects like to follow the curvature of that space. So,
for example, near a huge mass, space is bent and
objects like to follow the curvature of space, which brings
them towards the center of that mass. You jump out
of an airplane, space is curved there. Because you're near
the Earth and your natural motion is towards the surface
of the Earth, and you need acceleration. You need a
(39:24):
force to prevent you from moving in free fall, to
work against the motion of space and time. So I
understand Hans's question. Hans is like, hold on, you're saying
the Earth is accelerating. How can it be accelerating up
in the Netherlands and up from Perth? Right, it seems
like it's going in two directions. And that's because you're
thinking about the Earth as a single sphere moving in
(39:45):
one direction or moving in the other direction. Instead, imagine
it as a sphere with variable radius. Gravity is trying
to shrink the Earth down into a dot, and the
structure of the Earth is pushing back up and out
in every direction. So the answer is that it's accelera
up and out in the Netherlands and up and out
in Perth. Both are out away from the center. If
(40:06):
there wasn't that acceleration, if the whole Earth was just
a bunch of particles following the curvature of space time,
it would collapse into a black hole. That's what gravity
wants to do. It gathers stuff together because it bends space,
and then the motion of those particles follows that bend
space and things fall together. So Earth has to push
up and out just to maintain the same distance from
(40:28):
the center. So it's counterintuitive because now I'm saying you
have to accelerate just to maintain a constant distance from
the center of the Earth. That's very counterintuitive, but it's
true because their natural motion is to fall in towards
the center, and you have to accelerate, which means counter
your motion relative to gravity, to avoid doing that. So, yeah, Hans,
(40:49):
the Earth is accelerating up under you and up under
your nephew in Perth.
Speaker 1 (40:53):
Who does that make right? That's the important question.
Speaker 2 (40:58):
Let's just all sit down over a night, play the
meat honey and work it out.
Speaker 1 (41:02):
Oh no, let's never do that. Let's never ever do that,
or at least let's not be told that we're eating
meat honey if that's what we're having.
Speaker 2 (41:10):
All right. Well, I hope that cleared it up for Hans.
Let's send him o answer and see if he's got
some follow up questions.
Speaker 3 (41:16):
Hi, Daniel and Katie, thank you very much for your answer.
It was very enlightening. It still seemed somewhat counterintuitive to me,
but I believe I can now understand what you mean,
in particular the idea that you shouldn't see the Earth
as a solid object, but as a constant moving against
gravity to maintain the shape instantly. This reminds me of
(41:36):
Alison Wonderland. You have to run to stay in place.
I hope this makes any sense to you. Thank you
very much again, Hans.
Speaker 1 (41:43):
Well, thanks to everybody who submitted a question. Please, we
want more people to submit more questions, and if you've
got a question you want to share, you can send
it to us through our discord and you can find
the link to that on our website, or you can
send us an email at Questions at Daniel and Kelly
dot org.
Speaker 2 (42:00):
All right, and if you're still listening, we have one
more request for you. We want to know more about you,
not just what you're wondering in your questions about the universe.
We want to know who you are, what you listen to,
where you like to live, and what you do in
your spare time so we can get to know you
a little better. We have a survey for our listeners.
If you have a few minutes, we would love to
hear some more about you. You can find a link
to the survey on our website www dot danieland Kelly
(42:23):
dot org.
Speaker 1 (42:24):
Thanks everyone. Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio.
We would love to hear from you, We really would.
Speaker 2 (42:38):
We want to know what questions you have about this
Extraordinary Universe.
Speaker 1 (42:43):
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 (42:50):
We really mean it. We answer every message. Email us
at questions at Danielankelly.
Speaker 1 (42:55):
Dot 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 (43:05):
Don't be shy, write to us,
Hosts And Creators
Daniel Whiteson
Kelly Weinersmith
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