What weird thing in space is pulsing every 20 minutes?

Daniel and Katie talk about things in the sky that pulse, and a recent discovery of a puzzling set of pulses.

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Episode Transcript

Speaker 1 (00:08):
Hey, Daniel, is there still more stuff to discover out
there in space? Oh?

Speaker 2 (00:12):
My gosh, so much more stuff. Are you looking forward
to some more new discoveries?

Speaker 1 (00:17):
Well, I just kind of hope I'm not too.

Speaker 2 (00:19):
Late, too late for what?

Speaker 1 (00:20):
What do you mean, too late to get to name
one of these crazy things?

Speaker 2 (00:24):
Do you have a particularly good idea for a name?

Speaker 1 (00:27):
Well, I feel like scientists needs some new material like quasar, pulsar, blazar, masar, magnetar.
We need a new direction, we need some freshness.

Speaker 2 (00:38):
All right, I'm terrified to hear what you have in mind.

Speaker 1 (00:41):
I was thinking something like the Katie Orb. That has
a nice ring to it.

Speaker 2 (00:45):
Right, all right, I'll send that in. But are you
as sured that's what you want? I mean, what if
we discover something gross, like a planet made of slime
and it gets called the Katie Orb?

Speaker 1 (00:56):
Daniel, I would be honored.

Speaker 2 (01:00):
Be careful what you wish for. Hi. I'm Daniel, I'm
a particle physicist and a professor at UC Irvine, and

(01:21):
I do want to discover a planet made of slime.

Speaker 1 (01:24):
I am Katie Golden. I'm stepping in for Jorge. I
typically do a podcast on animals, but I love talking
about planets because they're kind of like big animals, but
round and.

Speaker 2 (01:36):
Weird planets out there might have weird animals on it. Right.
Have you thought about starting a podcast on exozoology?

Speaker 1 (01:44):
I feel like I would need a pretty good spaceship first,
and recording equipment that could span quite a bit of
broadcast distance.

Speaker 2 (01:53):
Well, I'm sure as soon as we discover planets filled
with slime and the creatures swimming around in them named
the Katie Orb, of course somebody will jump on the
podcast opportunity a podcast all about these weird, slimy aliens.

Speaker 1 (02:07):
It'll just be called a blobcast.

Speaker 2 (02:09):
The slime Cast. Well, welcome to our podcast, Daniel and
Jorge Explain the Universe, a production of iHeartRadio, in which
we cast our minds out into the universe to think
about planets made of slime, planets made of diamonds, planets
made of all sorts of weird things, to wonder about
whether there are planets out there like ours, or whether

(02:30):
our planet is weird and unusual. We think about all
the strange stuff that's out there in the universe and
all the strange stuff we find here on Earth. The
quantum particles, frothing up between our toes all the way
up to the hearts of galaxies and the mammoth black
holes that live in them. We try to understand the
entire universe and explain it all to you while keeping

(02:51):
you laughing.

Speaker 1 (02:52):
All right, I'm ready to learn about the entire universe
in about an hour.

Speaker 2 (02:57):
My usual friend and co host Orge can't be here,
but we are very happy to have Katie along for
the ride to learn about weird stuff in outer space.

Speaker 1 (03:06):
I love weird stuff in outer space. I always like
to imagine there's some kind of giant space whale out
there making its way slowly towards us.

Speaker 2 (03:16):
See. I knew you think about the universe and space
in terms of critters, right Who is out there? Who
is swimming through space? Who is jumping through an ocean
of slime?

Speaker 1 (03:26):
It's hard not to anthropomorphize the universe otherwise it feels
very lonely. So I like to think that there's stuff
out there wriggling and slimming it up, and when you meet.

Speaker 2 (03:38):
These space wheels, you're going to give them like a
nice slimy hug.

Speaker 1 (03:40):
Exactly.

Speaker 2 (03:41):
Well, there is something fascinating about space and the universe
because it's such a vast frontier. We are trapped here
on this tiny little planet, looking up at the sky,
wondering about what's out there in space, and knowing that
it is chok full of discoveries waiting to be made.
Every time we look up at the sky and invent
some new kind of eyeball for peering further out, or

(04:04):
hearing in a new frequency, or listening to a new
kind of particle, we always find something shocking, something weird,
something unexpected. Because space really is the final frontier. It's
a place to explore and to discover and to learn
what's out there in the universe, which of course is
the first step to understanding it.

Speaker 1 (04:23):
I do think it's an interesting way to look at things,
because there's this feeling sometimes I get of, well, science
has progressed pretty far, what more do we really have
to discover? But then when you try to think about
all of these unknown things about the universe, it becomes
pretty apparent that we know actually very little about the universe.

(04:46):
Our understanding of the universe is very it is a
fraction of what is actually out there.

Speaker 2 (04:51):
Absolutely, we know very little about how the universe works,
and part of that is because we have seen very
little of the universe. We have not significantly left the
Earth or its neighborhood. Right. Everything we have learned about
the way that stars form and galaxies come together in
the history of the universe, and dark matter and all
these big mysteries have come just from observing the universe

(05:12):
from Earth, which means we're limited to capturing photons and
other particles that happen to make their way to Earth.
And because things are very very far away, a lot
of the stuff gets missed. So if you think about
like the fraction of the Milky Way that we have
studied in detail, it's a tiny little tea spoon of
all the stuff that's out there. And the most interesting stuff,

(05:33):
of course, is the weird stuff, the rare stuff. So
as we continue to build our capabilities and develop new
techniques for looking out into the universe, we're going they
keep stumbling over weird cases, things that we thought were
impossible or that we never imagine we're out there in
the universe. Take an analogy from particle physics about learning

(05:53):
things from rare examples. When we smash protons together, we
make Higgs bosons sometimes but not very often. It takes
like trillions of collisions to make one Higgs boson. So
now apply that to astronomy. How many stars do you
have to look at until you find that one that
reveals something deep and true about the universe.

Speaker 1 (06:14):
I think that's also very unique because in a lot
of science, the key is looking at things that are replicable,
things that happen commonly, and it's not so much looking
at the extreme extraordinary cases. But I love that when
we look at the universe and the science of the universe,
like looking at these extreme cases can teach us so

(06:37):
much about the universe in general.

Speaker 2 (06:40):
Absolutely, And one really valuable clue we have when we
look at the night sky is how it changes. And
humans have been doing this for thousands of years, the Mayans,
the Chinese, the Indians, the Greeks, the even the Babylonians.
We're looking up at the sky and noticing, of course
how it changes with the seasons, and learning from changes
in the sky, how things worked out there, how the
planets remove mo and all this kind of stuff. And

(07:01):
modern astronomy does the same thing. We look at the
night sky and we look for things changing, because things
changing are clues, their hints. When the star explodes, you
have an incredible opportunity to learn something about the life
cycle of a star, or if a new star appears.
Anything that's flickering or changing in the night sky is
literally sending you a message that something exciting is going on.

Speaker 1 (07:22):
The night sky. It's interesting because it has this feeling
of something permanent, right, Yes, it does. As we rotate
around the Sun and as we spin on our own axis,
the sky also will change. But the idea that there
are actual changes happening to the stars in the sky,

(07:44):
I think it's something that is somewhat unexpected, right because
you look at the sky and you think, like, well,
sky's going to be the same, those stars are going
to be their stars are permanent, but they're not. They
can have their own lifespan. And then sometimes we're lucky
enough to actually see changes in the stars themselves during
their lifespans exactly.

Speaker 2 (08:03):
And it's a really important clue about the nature of
deep time. It gives us this different perspective. We know
actually that the universe is quite chaotic and quite dynamic.
You know, even our Solar system. The planets move in
and out and migrate. We used to have another big
planet that got ejected when Saturn and Jupiter came into
the Inner Solar System and then went back out to

(08:24):
where we find them. Now we know that the whole
galaxy is histories of collisions with other galaxies. Everything is changing,
it's just doing it on a much, much, much longer timescale.
And we are used to thinking about not seconds, not minutes,
not days, not hundreds of years, but sometimes millions of years.
So when we are lucky enough to see something change

(08:45):
in the night sky, we're looking at a very rare moment,
a transition between periods that might last millions of years.
So thinking about the night sky changing is really fun
because it helps you get that deep time perspective to
realize that the universe looks very different when you found forward.

Speaker 1 (09:00):
So when you say that these things take a lot
of time, are most of these changes very slow or
are there certain changes with stars that we can actually
see happening in real time, like an explosion or something
seems like it might actually be something that you see
over the course of minutes or hours or days. So

(09:21):
do we actually get to see things that happen rapidly
even though it took you know, an unfathomable amount of
time to get to that point.

Speaker 2 (09:32):
Yeah, we do. Sometimes it's really exciting. There are things
like supernova that happen over minutes or days or months,
and you can actually find records of these. In ancient astronomy,
the Chinese were keeping track of what they called guest stars,
which are comments, and supernova's all the way back to
you know, a thousand BC. It's really incredible how long

(09:52):
their records go back. And so these are the moments
when we can really learn something about the night sky,
things that do happen on our time scale. Things we
can observe change in minutes or hours or even months,
and so that's a really fascinating opportunity to learn something
about the night sky. And today that's exactly what we're
going to talk about. An accidental discovery by an undergraduate

(10:12):
student of something very weird in the night sky, something
different from anything we have ever seen before.

Speaker 1 (10:19):
Flying slime monster visitor.

Speaker 2 (10:22):
From the Katie Orb. Today on the podcast, we'll be
asking the question, what's the weird thing in space that's
pulsing every twenty minutes.

Speaker 1 (10:37):
You're telling me this isn't about a giant slime monster.

Speaker 2 (10:40):
Though I'm saying, we don't know, I'm not ruling it out.
You know, maybe there is a giant slime monster out
there that burps every twenty minutes, and that's going to
be the answer, right. That's the joy of science is
not knowing the answer going in. So this is a
fairly recent result and one that astronomers have been puzzling over.
And if you listeners sent it to me and said,
what's going going on here? Can you explain it? And

(11:01):
I love digging into recent science discoveries to help people
understand the context of them, what we've learned, what really
is mysterious about it, and what the various possible explanations are.
And this one's especially fun because we get to talk
about all the things in the sky that pulse. But
before we dig in, of course, I wanted to know
if people already had heard about this and had ideas
for what might be pulsing in the sky every twenty minutes.

(11:23):
So thank you very much to our group of volunteers
who answer these questions. If you would like to join them,
please don't be shy. Everybody is welcome. Just write to
me too questions at Danielandjorge dot com. You can record
the answers in the privacy of your own living room
and then just delete them before sending to me if
you don't like so, think about it for a moment

(11:44):
before you hear these answers. Do you know what kind
of things in the sky can pulse every twenty minutes?
Here's what people had to say.

Speaker 3 (11:52):
What pulses every twenty minutes? It can't be a pulsar,
because that's way too easy of a question for you guys.
But I believe that there's a heavenly body out there
that is producing a radio wave every eighty six seconds,
which I seem to believe is about twenty minutes, And
it was the little Green Man signal.

Speaker 2 (12:10):
What object pulses every twenty minutes?

Speaker 4 (12:13):
Well, I believe that pulsars pulse much more rapidly than that,
so I'm going I guessed, and might be something more
like a quasar. Pulsing makes me think of pulsars, so
spinning neutron stars, that's my guess. But I feel that
they can pulse they pose much faster than that, so

(12:35):
I'm not sure it.

Speaker 3 (12:36):
Is a pulsar that blips every time. Jeff Basos earns
one million.

Speaker 1 (12:41):
Dollars, so I'm somewhat surprised that only one person mentioned
the idea of this being like the doings of aliens
or the handiwork of some organical life form.

Speaker 2 (12:54):
Well, that's interesting. Is organic life typically that regular? I mean,
I know that humans can sense signals that pulse very
regularly because it's part of our sort of like digital
technological civilization. But are there examples in nature of things
that like pulse very regularly every twenty minutes?

Speaker 1 (13:10):
Well, maybe not every twenty minutes, although there are some
animals that have very slow rates of this. But our
heart beats or something that makes me think of something
with a very regular pulsating mechanism. But yeah, something that
pulsates with this sort of regularity does actually make me
think of biological processes. They may not be exact down

(13:32):
to the nanosecond, but there are a lot of biological
processes where you have a sort of pulsing I'm not
sure what animal would have a heartbeat that is once
every twenty minutes, but some animals can slow down their
heart rates quite a bit when they go into a
sort of a state of torpore.

Speaker 2 (13:52):
Well, isn't heart rate connected to body mass like the
larger you are, the slower your heart rate.

Speaker 1 (13:58):
Generally speaking, it can also be dependent on your metabolism.
So like a small thing like a wood frog that
freezes itself in the winter can slow its heart rate
down quite a bit, whereas a large thing that's running
is going to have a really fast heart rate. So
it has to do with your metabolism, which may have

(14:20):
something to do with your species or your size. Often
large things do have slower metabolisms, but it can also
depend on the state that you are in. So if
you're exercising, your heart rate's going to be pretty quick.
If you're a wood frog and you've frozen yourself in
the winter to kind of hibernate, then your heartbeat is
going to be really really slow.

Speaker 2 (14:39):
Well, the direction I was thinking was, you know, a
little mouse has its heart rate very very fast, and
a human is slower, and a big whale is even slower.
So I was wondering, like, how big of a space
whale do you have to have to have a twenty
minute heartbeat? Maybe it's a planet sized slimeball space whale.

Speaker 1 (15:00):
I like where this is going.

Speaker 2 (15:01):
Yes, we don't know, of course, whether this is an
actual alien slime whale or not. But we do know
that there are things in the night sky that pulse,
and lots of our listeners mentioned one of them pulsars
that we're going to dig into in a moment. But
there might be more things in the night sky that
pulse and that vary and that change than you might expect.
A lot of people look up for the night sky

(15:22):
and think that it's static, that it doesn't change, but
actually all stars have cycles. They're not just like static
burning balls of gas. They vary, they get brighter, they
get dimmer. Even our Sun, for example, changes its brightness
over an eleven year cycle.

Speaker 1 (15:38):
They're like huge and sort of deadly lava lamps.

Speaker 2 (15:43):
That's exactly right, because there are these big balls of plasma.
They're not just fire the way we have like a campfire.
There's fusion going on, and there's all sorts of convection
and lots of complicated processes that we still do not
really understand very well. Our own star, the Sun, has
this weird eleven year cycle where it's magnetic field flips

(16:03):
every eleven years with crazy regularity as far as we
can tell, going back a very long time. And this
has to do with the currents of plasma inside the
Sun like flopping over on top of each other. You
can think of these things like big spaghetti noodles and
they get bound up by magnetic fields and then they
snap and twist. So something is going on inside our sun.
That's like a clock. It's like a universe clock. And

(16:26):
every eleven years the Sun flips its magnetic field, and
it also changes its brightness, not that much, like zero
point one percent over eleven year cycles, but it does change.
It is variable.

Speaker 1 (16:39):
So this big bright spaghetti clock you were talking about currents,
it sounds like it has like these complex almost weather
patterns that follow a sort of timeline.

Speaker 2 (16:49):
Yeah, they have these big plasma tubes inside the sun,
these currents of these hot protons and electrons that are flowing,
and that helps make the magnetic field. Remember, the fields
come from moving charges, and the Sun is basically just
ionized hydrogen. You take the proton and the electron and
you give them so much energy that they don't want

(17:09):
to hang out together anymore. They want to be free,
so they are just flying around all of these charges
and then they flow in these big tubes and that's
what makes magnetic fields. But they like slip and slide
on top of each other, and sometimes they snap and
break and relax in various modes. It's extraordinarily complicated. We
don't have the technology to model the inside of the
sun very well because it is very complicated each of

(17:32):
the particles. Not only does it have location and momentum,
but you also have to think about their electromagnetic forces
between each other. These things can get very turbulent and
very chaotic, meaning that like a very small change in
one electron can cascade into a big effect for other electrons.
So you make a little mistake and it becomes very
quickly a big mistake. That's one of the things that
makes the Sun hard to model. It can be very

(17:55):
chaotic on its insides, and that's a weak point in
our science that sometimes we can simulate things because we
understand the fundamental rules, like we know electromagnetism, but we
can't necessarily model a lot of them all at once,
And the Sun is a lot of electrons to model.

Speaker 1 (18:10):
So you mentioned that it's very chaotic, but it also
may follow a sort of eleven year cycle. How do
you get things like cycles or regularity out of such
chaotic processes.

Speaker 2 (18:24):
Yeah, they're chaotic in the sense that a small change
in the initial conditions can lead to a large change,
and that's a problem often for our simulations, that if
we don't get things exactly right, then our simulations go wrong.
Inside the star, the process can be quite stable. Actually,
there are things that keep it on track, you know,
the magnetic field configuration of these plasma tubes have energetic

(18:46):
minimums that they like to settle into. But then the
magnetic fields get stretched and twisted, and then there's a
new energetic minimum that forms and they snap over into that.
And so that's the kind of thing that can give
you these regular processes. And our star is pretty constant
when it comes to this, but other stars are much
more dramatic. There's stars out there in the universe that

(19:07):
are very dramatically pulsating. They swell in size and they
also shrink, they get like bigger and smaller. Some of
these things pulse with a fairly regular frequency, or sometimes
multiple frequencies that can be either very regular or stochastic.
A classic example of these is very famous the cephids.
These are the ones that Hubble use to discover that

(19:28):
the universe is expanding because it's a very clever trick
to figuring out how far away these stars are by
how they are pulsating. It turns out if you measure
the period of their variation, like as they get brighter
and dimmer and brighter and dimmer, the time between being
bright and dim allows you to know the true brightness

(19:48):
of the star, Like there's a relationship there, whereas stars
that are pulsating faster might be brighter and stars that
are pulsating slower might be dimmer. And then you can
know how far away the star is because you can
measure the brightness here on Earth compared to the brightness
you know to be the case that you got from
the pulsation from the periodicity of the star, and that
tells you how far away it is. That was very

(20:10):
important early on for understanding the expansion of the universe,
because we just looked out of the sky and we
didn't know how far away are all these dots. Some
of them might be closer, some of them might be further.
It's not always easy to tell. So the variability of
the night skies actually are very important handbills scientifically for
understanding like the three D structure of what we're.

Speaker 1 (20:30):
Looking at so these sephids that were studied, we found
that they were starting to get demmer, so they were
starting to get further from Earth, showing that there was
an expansion of the universe.

Speaker 2 (20:43):
So for the cephids, we can measure their velocity relative
to Earth because we look at the light from them
and we see how it's shifted. Stars that are moving
away from Earth are red shifted. The wavelengths of their
light has been extended because they're moving away from us.
It's like a Doppler effect. So we can measure the
velocity of these stars. And then Hubble also was able
to measure the distance to these stars. He was able
to tell which ones were closer and which ones were

(21:05):
further away using this trick where he measured how they pulsed.
How they pulsed told him how bright they were, which
tells him how far away they are. So if he
knows how far away they are and he knows their velocity,
then he can compare those two things. And what Hubble
noticed was that stars that are further away seemed to
be moving away from us faster, and stars that are
closer by are moving away less fast. And what that

(21:28):
tells you is that the universe is expanding, that everything
is moving away from us, and things further away are
moving away faster. And that's the original Hubble's law, and
Hubble's constant relates these two things. How fast things are
expanding relative to how far away they are.

Speaker 1 (21:44):
Wow. So that's like we're able to tell things about
our universe just from the movement of stars. And because
these stars are pulsating, that gave us enough information to
be able to measure distance and velocity, which was the
key to understanding the.

Speaker 2 (22:00):
Yeah. And also this other great mind blowing moment of
understanding because we didn't know until then that there were
other galaxies in the universe. We thought we just had
this one galaxy and it was a bunch of stars
and that was it. And we saw these other little
smudges up in the sky that we now know are
other full galaxies, but we didn't know that at the time.
They couldn't tell how far away they are, so they

(22:22):
thought they were just little clouds of gas that were
inside our galaxy. They didn't realize they were mammoth collections
of other stars much much further away until Hubble measured
their distance using these variable stars. Using these things pulsating
in those other galaxies, and he could tell, oh my gosh,
these things are super far away. We totally got this wrong,

(22:44):
and all of a sudden instantly your whole mental picture
of the universe expands from we have this one galaxy
floating in space to while the universe is littered with galaxies.
It's a complete mind blowing moment to realize that the
universe has so many more galaxies than just ours.

Speaker 1 (23:00):
It is also kind of wild that we once thought
we were the only galaxy. I find that somewhat I
guess egocentric. I'm not really sure I get it. I mean,
at one point we thought Earth was the center of
the universe, so to think we're the only galaxy kind
of makes sense too. But also it is a little
bit We're a little bit full of ourselves here in

(23:21):
the Milky Way, aren't we.

Speaker 2 (23:22):
It can be really hard to put yourself in the
mindset of people who made assumptions one hundred years ago
or five hundred years ago. It seemed totally natural to
them at the time, and now to us seemed kind
of bonkers and obvious. It really goes to show you
how much our intuition is informed by science. You know,
what we think is obvious and natural has changed over

(23:43):
time as we've learned about the universe. And so that
tells you really shouldn't trust your intuition at all. It's
totally biased by what you've been told and how things
have been described to you.

Speaker 1 (23:54):
So I shouldn't be trusting my intuition. That's saying it's
time for a nap break.

Speaker 2 (23:58):
No, there you are on.

Speaker 1 (24:13):
All right. So we are back and we are talking
about the dynamic stars out there that pulse and change
and things that we can actually measure. So we talked
about these stars, the sephids that they're pulsating. Were the
pulsating of the sephids told us a lot about the

(24:33):
nature of the universe that it was expanding. It allowed
us to measure the distance to these stars. What are
other examples of stars changing that we can observe here
on Earth?

Speaker 2 (24:45):
So pulsating stars are not the only example of stars
changing out there in the universe. We see all sorts
of things changing, and every time this happens, we try
to understand it, like what's going on? You know, people
have been working on understanding sephids for a long time.
Because we'd like to know, so, what's going on inside stars?
How does the energy dynamics work. In the case of stephids,
we have sort of an idea. People think that, like

(25:07):
something inside the star might become opaque so that the
radiation basically can't escape, and that makes the star a
little bit darker. And then the star puffs up because
it's absorbing that radiation instead of emitting it. It puffs
it up, and then it collapses again due to gravity.
So there's some sort of cycle there. But these stars
just go to do this thing over and over again.
There are other kinds of stars that are much more dramatic,

(25:29):
where you have like huge amounts of material blown out
of the star, called like flare stars. Some of these
things can get very dramatic, Like the star can grow
in brightness by a factor of five or six in
just like thirty minutes. So imagine you're like sitting on
a planet near one of these stars, your sun bathing nicely,
and all of a sudden, the star is like six

(25:51):
times as bright as it was just a half an
hour ago.

Speaker 1 (25:54):
It's like that black Hole Sun music video, which gives
me a migraine I watch it is this a repeating
pattern or does it just happen one and once and done.

Speaker 2 (26:05):
These things are unpredictable. They're not like very regular. So
you'll be watching the star and all of a sudden,
it'll get much much brighter, very briefly, and then it'll
dim back down again, and they think it might be
something going on inside the star that's blowing out a
huge amount of material, and then it's settled down again.
There must be something chaotic happening inside these stars. But
this is not the kind of thing we expect our

(26:26):
son to do. Most of the flare stars that are
out there tend to be of the red dwarf variety.
And remember that red dwarfs are much more common kind
of star than ours. Our stars kind of unusual in
the universe, and most of the flare stars that we've
observed are these red dwarfs. And that's actually one hypothesis
for why life evolves around the not most common star,

(26:50):
because you might imagine, if red dwarfs are the most
common star in the universe, why is it that we
evolved around a weird star? And it might be that
red dwarfs are common, but they're just sort of like
inhospitable to life because it takes a lot of sunscreen
to survive. Your star getting six times as bright all
of a sudden, unpredictably.

Speaker 1 (27:08):
That's really interesting. So if most stars out there are
red dwarves, what kind of star is our sun?

Speaker 2 (27:15):
Our star is one of the category that they call
an F or G type star, So it's a bigger star,
and it's yellower, and so it tends to burn brighter.
Remember that smaller stars are cooler, which is why smaller
stars are redder, because red indicates longer wavelengths, which means
lower surface temperatures. And our sun is more yellow, it's
a little bit hotter than the typical red type of star,

(27:37):
So we live on an unusually hot kind.

Speaker 1 (27:40):
Of star, and so our sun doesn't have these sort
of star sneezes like these red dwarves have, and so
that protects us from having suddenly needing one hundred spf
every so often.

Speaker 2 (27:55):
Not entirely though, right our sun does have little sneezes,
you know. These coronal mass ejections can be fairly dramatic events,
where like loops of plasma get ejected, and some of
them can even bathe the Earth we had this event
in the eighteen hundreds where like all wires on Earth
were suddenly electrified because of the crazy magnetic and electric
fields that were coming from these events. So they do happen.

(28:16):
They're not neatly as dramatic as flare stars. But even
our sun can burp in our direction.

Speaker 1 (28:21):
Oh dear, uh oh what if Twitter goes down? Oh no,
that would be so bad.

Speaker 2 (28:28):
Blame the sun, not elon Musk.

Speaker 1 (28:31):
So we've got pulsating stars like the sephids, We've got
the red dwarfs who have their explosive sneezes. What other
kinds of star pulsating do we have?

Speaker 2 (28:44):
One of my favorite and the kind that was mentioned
by listeners when we ask them about this, are pulsars.
These are a very very cool kind of star and
they represent the end of the life of many stars.
So you know, stars form from having a huge block
of cold gas and dust that gravity gathers together until
eventually it's hot enough and dense enough that fusion can start.

(29:07):
And then fusion is fighting back against gravity. If we
only had gravity and then a blob of gas and
dust would just form a black hole straight away. But
because it starts to burn it emits radiation that's like
puffing back up against gravity, and it keeps it in
balance for millions or billions or trillions of years, depending
on the size of the star. Smaller stars burn longer

(29:29):
because they burn cooler. Bigger stars burn shorter and faster
and hotter and don't last for very long. And the
mass of the star also sort of determines what happens
to it. Like a star that's smaller, like less than
eight times the mass of our Sun, will eventually turn
into a red giant. It puffs up and then eventually
collapses and you get like maybe a white dwarf at

(29:50):
its core, which is just like a hot leftover blob
of the stuff that fusion produced.

Speaker 1 (29:55):
I knew blob monsters were out there. I knew it.

Speaker 2 (29:58):
And that's probably the phase of our star. It's going
to become a red giant and puff out all of
its material and eventually just be left as a white
dwarf which will cool over trillions of years to a
black dwarf. But if you have more stuff in that
initial scoop of matter, then you have like a massive
star that can become a red super giant. And when
that collapses, you've got a supernova, which can leave a

(30:19):
neutron star or a black hole, and a neutron star
is what forms a pulsar. A neutron star is a
blob of mass so dense that the electrons and the
protons that used to be in the hydrogen have gotten
squeezed together to form neutrons. Usually it goes the other way.
Neutrons like to decay into a proton and an electron,
but if you push them together hard enough, they will

(30:41):
actually reverse that process and make neutrons. So neutron stars
are some of the densest things in the universe, and
they're like the last step before gravity finally takes over
and collapses this thing into a black hole. So they're
very weird, very interesting things. Scientifically, we don't really underderstand
what's going on inside a neutron star, how it all works,

(31:03):
but they do something really really fascinating, which is that
they send us these regular pulses from space.

Speaker 1 (31:10):
So I imagine if I wanted to scoop like a
tea spoon of neutron star, it would be pretty heavy.

Speaker 2 (31:17):
It would not be good for your diet to eat
even a tea spoon of neutron star.

Speaker 1 (31:22):
It's a little too rich. So are these still emitting light?
What is pulsing for these neutron stars?

Speaker 2 (31:29):
So these things are not undergoing fusion, right, They're not
glowing the way that other stars are. And Jorge Make,
for example, quibble about whether we should call it a
star or not. And so these things are not glowing
in that sense. You can't look up at the night's
side and see a bright dot and say, oh, that's
a neutron star. We can see them sometimes because they
emit X rays, but the best way to discover neutron
stars is through their pulses. Because neutron stars are also

(31:53):
spinning really really fast. They have to spin because the
original blob of stuff that made them was spinning, and
now they've gotten really really small. Neutron stars are like
a few kilometers in size, but they have the mass
of like the sun or five times the sun.

Speaker 1 (32:09):
That kind of sounds like an ice skater, like a
figure skater. They can start a spin and then when
they collapse, like they kind of go into a ball,
they can spin even faster.

Speaker 2 (32:19):
That's exactly right, And they have to spin faster because
they're smaller and so to maintain the angular momentum, you
have to spin faster with a smaller radius. That's just
because the law of angular momentum is conserved in the
universe and it forces these things to spin faster as
they get smaller. Now that's spinning also makes a magnetic field, right,
because again you got charge particles in there and things

(32:41):
are spinning, so you get a magnetic field, and that
magnetic field will funnel some charge particles up towards the
pole the same way that like on Earth, we have
a magnetic field and it protects us from charge particles
from space. If an electron hits the Earth, it doesn't
just go all the way down into the Earth. The
magnetic field will funnel it up to the pole, which
is why you see like northern lights and southern lights.

(33:03):
Those are cosmic rays, charged particles from space that have
been swept up to the northern and the southern parts
of the Earth by our magnetic field. And so the
same thing can happen on these neutron stars. They have
charged particles that are swept up to the poles and
then emitted, so you get these very powerful beams being
emitted from the north and south poles of this planet,

(33:24):
because the magnetic field is sort of like focused it
instead of just like shooting particles off in every direction,
it shoots them up in these two beams, one north
and one south.

Speaker 1 (33:33):
Now, if you could stand on this neutron star, which
I'm assuming you can't without being grievously hurt, when you
look up at one of the poles, would you see
something like an aurora before you're presumably squished or tossed
off the planet.

Speaker 2 (33:50):
Well, the scale of these things is ridiculous. I mean,
the gravity is so strong on a neutron star that,
like the tallest mountain on a neutron star is about
a millimeter, and the atmosphere of the neutron star is
like a few more millimeters. So you'd have to be
like ant sized to be looking up from a neutron
star and see any atmosphere above you. It'd be pretty tough. Also,

(34:11):
you'd have to be like an Olympic strong man or
strong woman to be able to stand up on a
neutron star without being crushed or pulled apart by its
tidal forces.

Speaker 1 (34:19):
I mean, good news is on a neutron star, I
could scale the tallest mountain bad news. All my bones
would be jelly.

Speaker 2 (34:28):
Exactly. So you have this neutron star and it's spinning,
and you have this magnetic field which accelerates any protons
and electrons on the surface into these beams which shoot
out into space. And the fascinating thing is that sometimes
the magnetic field is not aligned with the spin of
the star, so you have like the star itself is spinning.
Now you have this beam shooting off the surface. But

(34:50):
the beam is not shooting on the spin axis. It's
shooting a little bit off, which means the beam is
like sweeping around through space. It's like forming a cone
of light and it sweeps around. And so these pulsars
are not actually variable in that sense. Their beam is constant,
but if the beam sweeps by you, it seems variable

(35:10):
because it sweeps over you and then it passes you
and then it comes back again. So it's sort of
like that figure Skaters holding a flashlight and as she
turns she blinds you once every revolution.

Speaker 1 (35:20):
I hate it when they do that at the Olympics.
But yeah, no, I mean it sounds like an intergalactic lighthouse.

Speaker 2 (35:28):
It's exactly right, just like a lighthouse. And when they
were first discovered. It was super fascinating. The first one
to be discovered had a period of about one point
thirty three seconds, one in a third second. So they
were looking up at the night sky and actually listening
for other stuff, and they saw this signal that went
like beep beep beep, very very regular and so of

(35:48):
course the first astronomer is to see this. Jocelyn Bell Burnell,
who unfortunately was overlooked for the Nobel Prize for this,
she at first thought, maybe this is aliens, giant space
whales or something else us a message because we didn't
expect the night sky to pulse and to pulse with
such regularity. It seemed artificial, it seemed technological.

Speaker 1 (36:09):
Yeah, that is interesting. As humans, we love a pattern,
and I think that patterns to us seem to signal
some intention. I guess like it's very easy to anthropomorphize
a pattern because we think of well, if something acts
in a regular pattern, it's got some kind of volition,
it's got some sort of consciousness because it is acting

(36:31):
in this pattern. But of course patterns can exist in
ways that have nothing to do with being alive or
having a brain. Like when we notice patterns, we have
this sense, and I think there have been some psychology
studies on this. When people see things like inanimate objects
like a marble or something and that's sort of doing

(36:52):
some kind of patterned behavior, they perceive it as having
sort of a like it desires, or having its own
sort of consciousness. But yeah, it's not necessarily indicative of
as much as I would like it to be a
giant space whale spouting its space spout, but it feels

(37:13):
that way very much. I think patterns feel very human,
they feel very intentional.

Speaker 2 (37:17):
But I suspect this is just human bias.

Speaker 4 (37:20):
You know.

Speaker 2 (37:20):
We imagine that like nature is messy and doesn't form
things like perfect circles and perfect pulses and squares, because
that's the kind of thing that we like to make,
and we imagine that differentiates us. But you know, there
are like squares in nature. You can find weird formations
of rock that are like almost perfect cubes or whatever.
So I imagine that when we do get to an

(37:40):
alien planet sometime we will be tripped up by this
expectation that things that form straight lines or geometric patterns
must be artificial and technological and intelligent, and maybe not right.
Maybe those aliens are messy slobs and their cities don't
look anything like all of this, right, And there are
of course examples in the universe when things are very
regular and yet not artificial, and these pulsars are a

(38:03):
great example. And because they spin so fast, their pulses
are very very short. You know, on a cosmological time scale,
these things are super fast. Right, we expect stars to
pulse to vary on the scale of millions or billions
of years. These things are pulsing at like seconds, and
some of them are spinning so fast millisecond. Pulsars pulse
literally every millisecond and with extraordinary regularity. You know, they

(38:27):
are more precise, more accurate, more repeatable at least than
our best atomic clocks.

Speaker 1 (38:33):
There's something that's hard for me to kind of visualize
with that, because when I think of space and you know, stars,
I think of very slow movements. But something that is
spinning that fast and flashing that fast, it's hard to
conceive of on that scale.

Speaker 2 (38:51):
It is really amazing. And there's another sort of time
scale for pulsars, which is that they do slow down,
like as we watch them, they seem very very regular,
can't spin and emit light forever, right, that would be
like an infinite energy source. This rotation and this beam
actually SAPs energy from the star and eventually they do
slow down. We think that it takes like ten to

(39:11):
one hundred million years for a pulsar to basically give
up its energy by beaming it out into space. And
that's actually kind of a short amount of time. Right.
Pulsars don't last very long, which means that like most
of the pulsars in the history of the universe are
now quiet. They did their pulse, they spread their lighthouse
information through the universe, and now they're dead. They're quiet.

(39:33):
So in something like ninety nine percent of the pulsars
that ever pulse are no longer pulsing.

Speaker 1 (39:38):
What happens to them after they stop pulsing? Do they
just remain a neutron star or do they turn into
something else?

Speaker 2 (39:46):
We hope they have a long career as emeritus stars.
You know, they continue to participate in the galactics discussions. No, exactly,
then they're just neutron stars. Right, there's still hot blobs
of neutrons, they're just not emitting anymore. They're not spin
as fast.

Speaker 1 (40:01):
I see. Well, the glory days are over for them,
maybe they can retire. Well, I'm gonna try to do
some spinning around to see if I can see what
it feels like to be a neutron star, and we
will be right back. So I just got really dizzy

(40:31):
trying to method act as a neutron star spinning around.
I feel nauseous, and I guess that's how these neutrons
stars feel too, if they can feel things. And I
sympathize and mentioned I.

Speaker 2 (40:43):
Like that you're trying to get in the head of
your giant spinning space whale. That's really very empathetic of you.
And when they do come to visit, I think that's
going to make you sort of like last on the
list of people to.

Speaker 1 (40:53):
Be eaten exactly. I think ahead, I plan for the
long game.

Speaker 2 (40:58):
My point is that it sounds like you're being altruistic
and empathetic, but really it's cynical, right, You're just really
looking at it for Katie.

Speaker 1 (41:05):
Like I'm hedging all my bets when it comes to
giant space whales. So I apologize for nothing. So we
just talked about pulsars, these neutron stars that's been incredibly
fast and sort of has that flash it like almost
like auroras that can flash really quickly, which kind of

(41:25):
blows my mind. So is this is have we gone
through all of the methods of pulsing in the universe.

Speaker 2 (41:31):
Yet those are the primary methods of pulsing. There are
other things like supernovas that do change in the night sky,
but really these are the biggest categories of things we
expect to see flare stars, Sephid's pulsating stars, and then
pulsars themselves. But of course there's always the opportunity to
discover something new. And I was so excited to read
this paper for so many reasons, not just because they

(41:54):
found something new that we don't understand in the universe,
but because how the discovery was made. This discovery was
made by an undergraduate physics student who is looking through
old data that had been sitting on disc for years
and nobody had looked at in this way. He was like, well,
looking for a research opportunity, found a professor and the

(42:15):
professor said, hey, I have this data. Why don't you
look through this and see if you can find something weird.
So he's analyzed this data looking to see if you
could find things that pulsed at rates that were longer
than anybody looked at before.

Speaker 1 (42:28):
This is a lesson to all undergraduates when you are
given what you think seems like busy work just to
get you out of the hair of some professor. Maybe not,
maybe you'll discover something new.

Speaker 2 (42:39):
And this is not the first time undergraduates looking through
old data have found something dramatic that has taught us
something about the universe. Check out our episode on fast
radio bursts. It's also something very similar and interesting. And
the lesson here also is sometimes you have to know
what to look for when you're looking through the data.
Like you can't just stare up at the night sky
and say, Universe, tell me what's out there.

Speaker 1 (43:00):
Wait, I've been doing, Mattgan, Well.

Speaker 2 (43:03):
You have to ask a question, and you have to say,
you know, are there big pulses in radio bursts or
are there things that pulse very very long periods, Because
the kind of things we know of that are out
there pulsars, and they're very magnetic versions magnetars tend to
pulse on seconds or faster. And so this guy went
into the data and looked for things that pulsed with

(43:23):
longer time scales, and surprise, surprise, surprise, he found one.
His undergrad's name is PJ. Hancock, and he was looking
through data from the Australian Murchison wide field Array.

Speaker 1 (43:35):
So when we talk about arrays, are these these are
big fields of detection equipment.

Speaker 2 (43:43):
Yeah, exactly. The Murchison whitefield Array is not the kind
of telescope you find imagine where you're like looking through
an eyepiece up at the universe. It's actually just a
bunch of antennas. There are four thou ninety six sort
of like spider like antennas that all just receive radio messages.
Each one is just like an intent to listen to radio,
but instead of listening to you know, Kiss FM or whatever,

(44:04):
it's listening to messages from space. And you have this
big array of antennas, which helps you, number one, capture
more signals and also tell where the signals came from,
because if you see the signal first on one side
of the array, then it like sweeps over the array,
then you can tell where you're in the sky it
might have come from.

Speaker 1 (44:22):
I love how we reverse engineer things that you find
in nature in terms of like detection. Animals that have
really good sensory organs that can really pinpoint where something
is coming from usually have this spatial element to it.
And I love that we have created as humans basically

(44:43):
all these sensory antenna on our Earth to turn our
Earth into like a giant et all detecting things out
in the universe.

Speaker 2 (44:53):
Well, I hope the space whales don't like to eat
beetles when they come here.

Speaker 1 (44:57):
It's a big space bird been. We're in trouble.

Speaker 2 (45:01):
So he found this thing in the data that releases
big bursts of energy kind of like a pulsar. But
the weird thing is that it pulses every twenty minutes. Actually,
it's even weirder. It pulses every eighteen point eighteen minutes.
And this is a very long frequency for something in space,
Like we don't have models for magnetars or pulsars that

(45:22):
pulse this long. And in seconds, this is like one
ninety one seconds. And when it does pulse, it pulses
for like thirty to sixty seconds at a time, sometimes
with shorter bursts. If you look inside the paper, it's
really fascinating. They have like a sketch of all the
different pulses that they captured. Once they found a few
examples of this. They went back into the data and

(45:42):
scanned more deeply and they found a bunch of these examples.
So they have like seventy one pulses from this thing
over like a three month period when this telescope was
observing data in just the right direction.

Speaker 1 (45:54):
Now I'm not a medical doctor, but if this was
the heart rate for someone, I would be concerned, because, yeah,
this looks this is a lot like there's a big
kind of spike and then there's a lot of little
spikes going on.

Speaker 2 (46:10):
You're like, this thing needs a pacemaker.

Speaker 1 (46:13):
Please help. My star is very sick.

Speaker 2 (46:16):
Well, we don't know, right, maybe this is a very
healthy signature for a giant space whale, but it's definitely
something very weird for a pulsar. Again, pulsars tend to
be much much faster. And so when they found this thing,
this undergrad took it to his advisor, astrophysicist Natasha Hurley Walker,
and she dug in more deeply. But she said, quote,
I was concerned that it was aliens when he brought

(46:39):
it to her. And I have so many questions about that, like,
what do you mean concerned? Why are you concerned?

Speaker 1 (46:45):
Not elated? And not ready to show them how you've
been trying to empathize with them by spinning around really fast.
This is why I plan exactly.

Speaker 2 (46:54):
So they dug into this to try to understand, like,
what is this thing? Where is it coming from? And
one of the first things they had to do was
to understand the period of the pulses. But they noticed
the pulses didn't actually line up in a very nice period,
like the separation between the pulses wasn't perfect. And that
turned out to me because this thing is not coming
from our solar system. It's coming from something much much

(47:16):
further away. And as the Earth goes around the Sun,
it changes the frequency with which we observe these things.
So once they corrected for the Earth moving around the
Sun and like not capturing the signal at the same
place in our orbit as we go around, they found
a much more precise fit. So that tells us, Okay,
it is really very regular, and it's coming from somewhere

(47:37):
far away. It's not like, you know, behind Jupiter or
something like that. This thing is outside of our solar system.
It's not also orbiting our Sun.

Speaker 1 (47:45):
I mean, that's kind of comforting. I'm glad that this
pulsating mystery object isn't just hiding behind Jupiter ready to
jump out at us. So we don't We don't even
know what it is. We don't know if it's like
a neutron star. We don't, like, what do we know
about it other than it has this weird twenty minute
ish interval and it's super far away.

Speaker 2 (48:08):
We don't really know. We know that it's about four
thousand light years away, and they can use another trick
to tell the distance, which is how the light of
different frequencies is arriving on Earth. It doesn't all travel
through the universe at the same velocity, even though of
course light always has the same speed in a vacuum.
Space itself is not a perfect vacuum. There are electrons
all over the place, and that tends to effectively slow

(48:30):
light down, but just so at a different rate for
different frequencies. This is called dispersion. So the dispersion of
the signal tells us how far it's gone through this
like electron gas that's filling space, because we know something
about the density of the electron gas, so sort of
reverse engineering that you can tell by the dispersion that
it's about four thousand light years away from Earth, which

(48:54):
means that it is in our galaxy. It's not in
like another galaxy, which would be millions of light years.

Speaker 1 (49:00):
Okay, so we do have to share the galaxy with
whatever this is. So I do want to understand it better,
so if it ever decides to visit, it knows I'm
on its team. What else do we know about this?

Speaker 2 (49:12):
So we know that it's kind of got a broad signal,
meaning that it admits not just at a single radio wavelength, right,
And this convinces some people that it's not aliens. People think,
if we're going to get a message from aliens, it's
going to be at like one frequency, the way that
we tend to send radio messages, you know, kiss FM
is different from another frequency, like you know one to
one point one rocking from the eighties or whatever. All

(49:34):
your different stations are different frequencies, and so people imagine,
if we're going to get a message, it's going to
be at one frequency, and this one is sort of broad.

Speaker 1 (49:41):
I don't know though, because like what if the aliens
want to really reach out to whoever, so they're trying
to send it out as on as many frequencies as
possible to make it more likely someone picks it up.

Speaker 2 (49:54):
Yeah, exactly, We don't know, right, It's another case of
like anthromorphizing, how aliens might send their messages. So another
thing to look at is the potential magnetic field of
this object, if it's a pulsar or a magnetar, which
is just a pulsar with a very large magnetic field
that affects the kind of light that comes from it.
Like the photons that come from these stars have a

(50:15):
different polarization based on the magnetic field, and this seems
to have a very strong magnetic field on it. It's
a very bright object, so that points toward it being
a magnetar, but it would be very strange because it's
a very long period magnetar. Like if you look at
the distribution of pulsars magnetars that we've seen so far,
they all clustered have very short periods. So this is

(50:37):
like a big outlier. This is like a very weird
one from the point of view of like how fast
it seems to be spinning.

Speaker 1 (50:44):
What is something that could affect the speed of its spinning,
Like would that be size of it or something else.

Speaker 2 (50:51):
It might be that it's just kind of old. Remember,
these things eventually do slow down because they are emitting radiation,
and so they last for tens or hundreds of millions
of years. So it might just be that we're seeing
one sort of at the last moment. But the weird
thing is that we've never seen one like this before,
and we've seen lots and lots of pulsars in the universe.
So either these things are rare and it just takes

(51:12):
a while of observation before we see one of these
kinds of things, you know, like there's a tale of
a distribution. You have most of them in the bulk
and a few very slow ones that are sort of
fading out, and you just have to keep looking for
a long time, the way we have to like collide
particles for a long time before we see a Higgs boson.
You have to keep looking before you see the rare ones,
and there's just now emerging because we've been paying attention

(51:34):
for so long. Or it might be a new kind
of thing, right, it might be something else out there,
not a magnetar, some new kind of astrophysical object that
has a different kind of behavior. And that's frankly my hope,
because that means that there's something new that the universe
can do, right, and it's sending us literally sending us information.
It says, be be beep, there's something going on here.

Speaker 1 (51:54):
I do like the sort of funny irony though, if
it is just a grandpas star, just like.

Speaker 2 (52:00):
Oh, what's going on over there?

Speaker 1 (52:02):
Just gotta slow down a little bit, you know, and
we think it's some new exciting thing, but it's just
old star, old and slow. Somehow. That's cute to me
that stars slow down when they get older, just like people.

Speaker 2 (52:17):
So people are trying to study this thing in further detail.
They're like looking at it across a range of frequencies,
understanding its X ray emissions because magnetars tend to be
fairly quiet in the X rays. So they look for
X rays from this thing and didn't see any, which
is sort of consistent with being a magnetar, but not
really a smoking gun because you're like not seeing a
signature instead of seeing a signature. So what they're doing

(52:39):
now is they're looking for more of these things, Like
we have a bunch of data that nobody's analyzed that
might have more examples. It might be like that data
set that undergrad was looking at could have dozens of examples,
or other radio telescopes around the world might have taken
data with this in it and nobody else had noticed.
So it's exciting that you can make discoveries like in

(53:00):
the data that we already have like sitting on computers.

Speaker 1 (53:03):
Yeah, I mean, it seems that the key is knowing.
Like you said earlier, the key is knowing what to
look for. It's hard to spot a pattern if you
don't even know what you're supposed to be focusing on,
or like what timescale you should be looking at.

Speaker 2 (53:18):
Yeah, there's something really deep there about how we make
discoveries and how we look out in the universe, what
we notice and what we don't notice. Because the universe
is like a tsunami of information, you can't pay attention
to everything. You can't notice everything, so our brains tend
to filter and pattern match. We can only really see
a tiny fraction of what's out there in the universe,
even just surrounding us. Right, people are very oblivious to

(53:40):
obvious stuff if they're not looking for it. So what
we see in the universe depends on what we look for,
which means we might be missing all sorts of crazy
stuff that's happening out there just because we haven't been
asking the right questions and we didn't have patient undergrads
to sift through the data in the right way. Right,
and in one hundred years or five hundred years, people
might laugh that how obvious these discoveries were to make

(54:02):
if we'd only known to ask the right questions.

Speaker 1 (54:05):
That's why it's really important for people in academia to
remember that undergrads are people too.

Speaker 2 (54:12):
And for you out there to remember that there's lots
more things to discover in the universe, really basic, low
hanging fruit that almost anybody could figure out if they
have the interest and the patience. So if you have
aspirations to become an astrophysicist one day, don't worry. This
plenty of stuff for you to discover, all right. Thanks
very much Katie for joining us on today's tour of

(54:33):
pulsating space whales and slime orbs or maybe just magnetars.
And thanks to our listeners for coming along another ride
as we talk about the weird stuff that's out there
in the universe.

Speaker 1 (54:43):
I'm going to do some more spinning to see if
I can feel what it feels like to be this mysterious,
pulsating object.

Speaker 2 (54:51):
And when they get here, they're not going to love you, Katie.
I'm sorry, they just could eat you like everybody else.

Speaker 1 (54:57):
I don't know. If I'm so dizzy that I've thrown up,
they may not to eat.

Speaker 2 (55:00):
Me, or maybe that makes you delicious. Either way, Thanks
everybody for listening in tune in next time. Thanks for listening,
and remember that Daniel and Jorge Explain the Universe is
a production of iHeartRadio. For more podcasts from iHeartRadio, visit

(55:22):
the iHeartRadio app, Apple Podcasts, or wherever you listen to
your favorite shows.