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October 20, 2020 45 mins

Is it possible that there are magnetic fields.... everywhere?

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Episode Transcript

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Speaker 1 (00:08):
Hey, Jorgey, I have a cool idea for a totally
new gadget. Is it an automatic banana pelar? That's you,
You're an automatic banana pelar. No, it's a space compass
on nice, So I tell you where to find bananas, uh,
your refrigerator. Now, like a compass on Earth right tells

(00:28):
you where North is based on magnetic field. Right, So
this space compass would use the Sun's magnetic field to
tell you where you are in the Solar system. That
sounds cool, But isn't that just like a regular compass.
That's the genius part. There are no engineering or design costs,
just cost to bananas. Anything I can do to cut
out the engineers. Hi am or handy cartoonists and the

(01:06):
creator of PhD comics. Hi, I'm Daniel, I'm a particle physicist,
and I'm moonlight as an inventor of ridiculous things and
ridiculous podcasts. Right, Let's see what I can make in
a particle colliderary that I could sell on Etsy. Let
see if we can collide science and bad puns and
see if anyone will listen. Maybe I should list many

(01:27):
black holes on my Etsy shop and see if anybody
buys one. Are those for sale? Can you buy one
from the LHC. Everything has a price, right, you give
me a hundred billion dollars, I will give you a
black hole. You would totally do it, wouldn't you. The
l a C would totally do it. They'll take that
money well after the check cash is yes. But welcome
to our podcast Daniel and Jorge Explain the Universe, a

(01:47):
production of I Heart Radio, in which we talk about
all the things that we can do in the world
and all the things that we can't do in this world,
even if we have a hundred billion dollars. We zoom
out into space and think about what's there, what's seeing?
Why are things here? Why does the universe work the
way that it does. Why doesn't it work some other way?
All the things for sale and that you can get
for free ad cern gift shop. Can you get a

(02:10):
free superconducting magnet that you don't use anymore? No, we
do not give those away. I think you can get
a sticker though. A sticker is it a super conducting sticker? No,
it might have a picture of a Higgs Boson collision
on it, so it's pretty fun. Yeah, we like to
talk about all the amazing things out during the universe,
all of the things that are here on Earth and

(02:31):
that we can discover and look closely at, and all
the things that we can quite see that are out there.
That's right, because humanity is taking a mental voyage of exploration.
We are stuck here on Earth for the time being.
What we'd like to understand what's out there? How do
things work? So we use our telescopes and are clever
ideas to probe the cosmos, And every time we do,

(02:53):
we find something weird, somebody that shakes the very foundation
of our understanding of how the universe works and what
it's old with. Do you think humans have a kind
of a version of fomo like fear of missing out?
That's what we're always looking out into space, trying to
find couder things. Yeah, maybe we're just stuck in a
boarding corner of the universe and the real party is

(03:13):
happening somewhere else at the center of the galaxy or
in another galaxy, and if only we were there, we
could be partner. Well, you know what they say, be
careful about having an interesting life. Well, maybe the aliens
are gathering together in some sort of like Universal Physics
Conference and revealing the secrets to the universe, and we
just weren't invited. Man, you do have fomo. I have

(03:38):
fear of missing out on alien physics. What's the acronym
for that, A phomo. But yeah, I would like to
talk about all the amazing things out there. And turns
out that there are a lot of very interesting things
out in space, things you can't see, but that we
can potentially feel. That's right, and humanity is busy building
new kinds of eyeballs, ways to look at space, ways
to hear messages from outer space to give us clue

(04:00):
as to what's out there, and every time we do,
we find something weird. Of course, there are planets, there
are stars, there are galaxies, there are supernovas, but there
are also other amazing things we can listen to. So
to be on the podcast, we will be asking the
question does space have a magnetic field? Now, Daniel, we

(04:21):
have a magnetic field here on Earth, like the Earth
has a magnetic field from the north pole to the
south pole, and so compasses work and it helps protect
us from cosmic race that are coming from space. And
so I guess the question is does space have a
magnetic field to like, is there, you know, like a
universe wide or galaxy wide magnetic field. Yeah, it's a

(04:44):
great question. And if you ask people this question, you know,
maybe twenty years ago they would have said, how could
the universe be filled with a magnetic field? Magnetic fields
and need sources, right, they need magnets or spinning loops
of charge or something. So what could possibly j generate
universe wide magnetic field? That's absurd, right, And my favorite

(05:04):
thing about physics is that things that were observed twenty
years ago become reality and then accepted wisdom and then
later eventually obvious. And you're like grumpy its students for
not understanding it in a ten minute explanation, and the
cutscene montage of physicists throughout his roy would be like,
that's ridiculous. Wait, never mind, that's ridiculous. Wait never mind. Yeah, yeah,

(05:26):
that can't be true. Oh, actually it is. And then
to the students, why don't you understand this? So you're
saying that there are magnetic fields in space? Yeah, and
this is wonderful history of discovery. As we look further
and further out into space, we discover magnetic fields where
we didn't expect to see any and we're forced to
come up with more and more ideas for what could
be generating them. And this is giving us a fascinating

(05:47):
window into how the universe was constructed and maybe even
like solving deep problems and concerns we have about understanding
how the universe expands. Sounds deep. It's quite a magnetic topic.
Deep answers about deep space. Is magnetically attractive to this topic? Well,
I feel kind of positive and negative about it, but yeah,
I guess the idea is that, you know, we have
a magnetic field here on Earth. You know, I have

(06:09):
a compass. It tells me which way is north. But
as I imagine myself floating out into space, I would
imagine that that compass doesn't work. Like you know, if
you're way far from the Earth, where would it point
to you. It wouldn't point to the north or the south.
But you're saying that a compass in space would be
pointing somewhere. Yeah, a compass in space would be pointing somewhere.

(06:30):
And I think it's useful to sort of take a
mental journey from the Earth and think about the magnetic
fields as you get further and further away from our
Earth and Solar system and galaxy and think about where
those magnetic fields come from, and that will help us
understand where they're not coming from or what we're confused about. So,
as usual, Daniel was wondering how many people out there

(06:51):
knew that there are magnetic fields in deep space? That's right,
and so I asked folks to pontificate on this question.
And if you'd like to participate and answer questions you
are unprepared for, please write to us at questions at
Daniel and Jorge dot com. Think about it for a second.
If there are magnetic fields in space, where do you
think they would be coming from. Here's what people had

(07:12):
to say. I guess this could be a definition problem
of what deep spaces. If you mean like nothing in
this space or quote unquote nothing possibly not, but a
few mean like are there magnetars out there? Then yeah,
there's magnetic fields and deep space. I guess so as

(07:32):
long as there are electro magnetic forces, there are magnetic fields.
I would say yes, because I think you mentioned on
a previous podcast about nuance that photons travel through the
electro magnetic field. I think Earth has one right for protection,
but in deep space. Would it be like a field

(07:54):
that attracts or repels objects, Possibly, but they would probably
be extra dream we weak. Yes, of course, should be
magetive fields. I don't know by deep space, like if
it's an a void, probably not, because I think magnetic
fields require like matter and energy to be there. But

(08:15):
around nebulas and stuff, then yes, I would say there's
magnetic fields alright. A lot of very um cautious answers.
We even seem to think that there are magnetic fields,
but nobody seem to have an idea where they come from. Yeah,
people think that there are things out there, like magnetars
and stars, etcetera. They create magnetic fields. But we're talking
about out in deep space, far from any concrete source,

(08:39):
things that aren't obviously generated by some spinning little particle
or moving current of charge. Well, I see, we're talking
about like way out there where there's nothing around you. Yeah, exactly,
because I imagine if you're in your Earth, then there's
a magnetic field here, and maybe other planets have them,
and maybe other objects have them. But like if your

(09:00):
own space but nothing around you, would there still be
a magnetic field. Yeah, and anywhere you find a magnetic field.
You get to ask the question where did it come from?
What's making it? Right? And that lets you investigate like
the source and the history and the understanding of like
what's going on inside. You know, Like when you discover
the Earth as a magnetic field, you get to ask, well,
what's making it? And that reveals a fascinating picture of

(09:21):
what's going on inside the Earth. It's not just like
a cold static blob. It's called like massive currents of
liquid metal. That's a pretty cool realization. So discovering magnetic
fields is an awesome clue that leads you to understanding
what's going on around because it's cool to think that
the Earth isn't just like a you know, like your
average kitchen magnet that you know, it's static and it's

(09:41):
just it just hasn't a magnetic field to it like
the one from Earth. It's because we have like a
generator inside of the Earth, like a living moving you know, dynamo. Yeah,
there's energy. They're right. Those liquids are flowing and they
create a magnetic field, and then the magnetic field makes them.
Liquids flow more because are charged and they get pushed
by the magnetic field and so it builds on itself. Yeah,

(10:04):
we call that a dynamo. So that's pretty awesome. We
have a little magnetic engine inside the Earth that's powering
this magnetic field, and that lets you wonder. Every time
you find a magnetic field, you can ask like, where
is the energy coming from to create this magnetic field.
So it's like finding out that there's something happening in
an empty room and you're like, well, what's going on
in the walls, and so that's kind of what's happening

(10:25):
out in space. So Daniel step us through. Maybe for
those who are not super familiar with what a magnet is,
remind us where they come from and what do we
know about magnetic fields. Yeah, so magnetic fields are fun,
and in our universe, we don't have pure sources of
magnetic fields, like you have a pure source of an
electric field, which is just an electric charge like an

(10:47):
electron or a positron. They can just create an electric
field around them, but we don't have that in our universe.
That would be called a magnetic monopole. Instead, we can
only create dipole fields, and these are created by like
moving elect charges spinning in a circle for example. So
a ring of current can make a magnetic field. That's
an electro magnet. You can also have metals that are magnetized,

(11:09):
and there the magnetic field comes from the spin of
the electrons. There's a electrons moving around in a circle
around the nucleus or actually having a weird quantum spin themselves.
So fundamentally, magnetic fields always come from some electric charge
that's in motion. And maybe that's the motion of the
liquid inside the Earth, or conductive plasma in the sun

(11:30):
or something else. But they always have this same kind
of source as far as we're aware, Like, it doesn't
seem to be like a fundamental property of the universe
or of matter or of charge. It's like you need
something to be happening to have a magnetic field. Yeah,
and now all of space has the capacity to have
magnetic fields, right, All of space we think of has

(11:50):
quantum fields in it. Right. Those fields are like possibilities
for charge. It's like, you know, there are slots there
and at any point in space you can put energy
into the magnetic field or the electric field, or the
Fermion fields or the Higgs field or whatever. Every point
in space has these fields, but sometimes have zero value
and some of the fields can actually go down to zero,

(12:12):
and the magnetic field is one of those. So all
of space has the capacity for a magnetic field, but
we're interested in, like, what's creating energy in that magnetic field?
Where is that coming from? In cases when there is
a magnetic field like around the Earth. Wait, are you
saying that there's a quantum magnetic field, just like there's
an electric field for the electron. Absolutely, all these fields

(12:32):
are quantized, and in fact it's very close connection between
electricity and magnetism, and in quantum field theory we just
treat those two as one. But yes, absolutely, the magnetic
field is quantized, and one quantum of the electromagnetic field
is of course a photon of the electromagnetic field. Yes,
because in quantum mechanics we think of electricity and magnetism

(12:53):
is just two sides of the same coin. Classically we
see to have slightly different phenomena, but we understand there
very closely related did so we think of them as one,
and a photon actually is an electric field and a
magnetic field sort of oscillating and supporting each other. It
goes from a magnetic field to an electric field back
to a magnetic field creating each other. A photon is

(13:13):
sort of this amazing cycle of energy flowing between one
of the fields and the other. See. But I think
what you're saying is that, you know, unlike a matter
field or like a force field, magnetic field can't just
like have energy on its own, like you're saying, it
sort of needs activity in another field. You know that
for it to have any kind of activity. That's what
we've seen so far. All the magnets that we have

(13:35):
seen have a source right there, are not constant, they're
not fixed. The magnetic field comes from the emotion of
a charged particle. We'll talk later about whether it's possible
for space to just sort of have a magnetic field
on its own. That would be fascinating, all right, So
we know that the Earth has a magnetic field, and
we know that the Sun has a magnetic field, right

(13:55):
because I guess it's it has kind of a stuff
inside of it flowing in circles and creating some sort
of current. That's right in the Sun. We think that,
similar to the Earth, is just like flowing currents of
charred stuff creating the magnetic field, and the Sun's magnetic
field is very very powerful, much more powerful than the
Earth's magnetic field. And if you are on the surface
of the Sun, your compass would be much more effective

(14:17):
than the compass on the surface of the Earth. Don't
recommend doing any hikes on the surface of the Sun,
of course, and you'll need more than a compass if
you do. Being lost in the surface of the Sun
is the lease of your problems. That's right. And the
Sun's magnetic field is actually really fascinating. We have a
whole episode plant about that because it's all sorts of
weird mysteries, like, unlike the Earth's magnetic field, it flips also,

(14:39):
but it does so on a very regular cycle, like
every eleven years boom, it flips over the north and
the south. The Earth's magnetic field flips very irregularly and
much more rarely. But the Sun is like clockwork, so
it's got a fickle field. So and also the galaxy
as a magnetic field, I guess because the galaxy is
kind of spinning, right, it's got a lot of stuff
going around in a circle. Is that what's generating the

(15:01):
magnetic field for the galaxy. So we have some understanding
of the Earth and the Sun's magnetic field. The galaxies
magnetic field is where we start to be a little
bit confused, like we don't really understand why the galaxy
has such a strong magnetic field. You know, if you
give the galaxy sort of a seed, a magnetic field
that begins, then the spinning, you're right, can make that

(15:22):
magnetic field stronger because you're slashing around big, heavy stuff
that can support it. But without that seed, you don't
get a very strong magnetic field just from the spinning.
The magnetic fields are interesting that way that they can
be enhanced more easily than they can be created. Like
you make a magnetic field, it organizes the magnets around
it and builds on itself, but you need that initial seed,

(15:43):
and we don't know where that initial seed for the
galaxies came from. It's actually very similar to the problem
we have with supermassive black holes. It's like you can
have a big black hole in the center of a galaxy,
but how does it get that big? And we have
the same problem with the galactic magnetic fields that we
don't really understand how they got so strong, how they
started and then got strong. Are their galaxies without a

(16:05):
magnetic field, or did they all have them. They all
have them, and they're actually important for forming stars because
the magnetic field helps channel all the gas and dust
and keep it together and not as diffuse, and that
helps of course collapse it into forming stars and all
that kind of stuff. And so it's pretty important part
of being a galaxy as having a magnetic field. It
it helps you evolve in the way that we expect.

(16:27):
And there's some variation of course in magnetic field galaxy
to galaxy, but they all have them, and then having
stars makes you more attractive to in magnetic yeah, exactly.
All right, so let's get into what else has a
magnetic field out in space, But first let's take a
quick break. All right, Daniel, we're talking about magnetic fields

(16:56):
in space, and we know that things have them, like
the Earth in the Sun and the galaxies. But the
question is does space, like empty space, like the space
between where there's nothing, does that have a magnetic field.
And so we were at the point of galaxies that
have magnetic fields, but then the galaxy clusters happening that

(17:16):
fields too. Yeah, it's amazing. You take your compass, right,
you're on Earth that has a field. You zoom out
the sun controls your compass, you zoom out to the galaxy,
and your galaxy then controls where your compass points. But
then as you leave your galaxy, you can ask, like,
are there magnetic fields between galaxies in these galactic clusters?
And so it's a very recent paper where people were

(17:38):
studying this and trying to measure magnetic fields between galaxies,
and to their frankly great surprise, they found that there
are magnetic fields between these galaxies. They are these like
filaments of gas between the galaxies that they used to
understand whether they're magnetic fields. And there are magnetic fields there,
and nobody knows what meaning, kind of like iron filings,

(18:00):
Like we're seeing things move around in between galaxies that
seem to be moved around by a magnetic field. Yeah,
it's really hard to measure magnetic fields for something else
you're looking at. Right, we can't take a compass and
like go out there and say, well, what's the magnetic
field here between the galaxies because we can't get there,
we can't send a probe. So all we can do

(18:20):
is try to understand the impact of the magnetic field
on the stuff we're looking at. And so, like you say,
you can look at iron filings on the table and
see the magnetic field lines. But here, we can't toss
iron filings between the galaxy. So we have to find
something that's already there and use it as our indicator,
like if it if it allies or it falls into

(18:40):
some sort of funny pattern, then that would tell you
there's a magnetic field there. Yeah, and actually our best
indicator are not objects like that, but electrons. Electrons as
they whizz through space are bent by magnetic fields that
tend to curve around magnetic fields. Just like particles that
hit the Earth, they hit our magnetic force field, they're
spiraled up around those lines towards the north pole in

(19:03):
the South pole, which is what causes the Northern and
Southern lights. In the same way, these electrons out there
in deep space, if they feel magnetic fields, they tend
to bend. And anytime a charge particle bends, it gives
off a photon. It radiates a photon that's sort of
like a signal for how it's happening. And we can
capture those photons and say, oh, look, electrons over here

(19:25):
are bending, so there must be a magnetic field. Interesting,
But how do you tell if they're bending, like can
you see it on a telescope or do you have
to somehow measure there's spin or how do you tell
their bending? We can't see the electrons directly at all.
These are electrons that are like a billion light years
away or millions of light years away. We don't ever
see the electrons. We only see the photon they give

(19:46):
off when they bend. And those photons have sort of
a characteristic signature that have like a certain energy you
would expect, and you look at patterns, and if there
are magnetic fields, you then expect to see like a
coherent pattern of electrons all giving off this same kind
of photon when they go through this region. What what
you mean? What how does it change the light that

(20:07):
it's meaning just from its velocity or it's a fundamentally
different these photons. When an electron gets bent, right, when
it changes direction, how does it do that? To do
that and conserve energy and momentum, it has to sort
of push off by shooting off a photon, and so
a magnetic field induces this. It says, al right, electron,
kick off a photon and change directions, and that's how

(20:27):
like all the energy momentum of the original particles preserved,
and we see that photon, and can we distinguish those
photons from like any other random photon. Well, a photon
is a photon, is a photon. They're all just photons.
But that was a pretty deep statement, huh. But these
tend to happen at characteristic energies, Like we know how
fast electrons tend to be moving and how strong these

(20:48):
magnetic fields are, and so that predicts the energy of
those photons. And again we expect them to be sort
of coherent. We expect to see like these kind of
photons all coming from the same direction if there is
a big athnic field there. But I'm glossing over a
lot of technical details. It's a really hard problem. They
build this amazing antenna to try to capture these photons,

(21:09):
and it took them years of data analysis to like
remove all the noise and understand if these really photons
from electrons far away. It's a difficult problem, but I
guess the main point is that you look out into
this sky into space, yes, and the way that we
look out into space is sort of awesome. I was
talking earlier about every time we opened a new eyeball,
we see something amazing in space. Here, we're looking into space,

(21:30):
not with visible light with these are in telescopes or
eyeballs in a literal sense that we're using to look
out into the universe. These are radio frequency antennas, but
they're still photons, right, It's still light. It's just a
higher frequency, that's exactly right. Radio waves are electromagnetic radiation,
which means that pulses in them are photons. And so
these are just photons with really really long wavelength, too

(21:53):
long for you to see with a visible eye or
for us to see with hubble. So the way they
do it is they have twenty thousand and tennas that
they spread across Europe. What really big device because these
wavelengths are so long, they can be like kilometers in
wavelength that you need a really big device to capture them.
Twenty Yeah, that's a lot. It's a lot. Do you

(22:14):
need a grad student for each one? Or how does that?
How do you keep trying them and how do you
keep them clean? It's a lot of work, right, And
these things are just like sitting out in the field
somewhere anywhere they can put one. Basically, they put one
it's a really awesome distributed device because you we never
take like all of Europe and turn it into a telescope,
though I'm sure some astronomers I wish you would. But

(22:34):
you can just sort of like embed these telescopes across
the continent and then stitch it together into effectively a
virtual telescope. That's did they try to disguise as cell
phone towers, disguise as trees, but that these guys and
is like satellite TV on rooftops. It's a great program.
It's called Low Far l O F a R. And

(22:55):
they have this awesome program and they really did a
lot of work. And one of the hard things is
that when radio waves come through the atmosphere, they get
fuzzy because the atmosphere interacts with radio waves and so
basically the picture was like crystal clear across millions of
light years and then it gets to our atmosphere and boom,
it gets fuzzed. So they have to solve that problem,

(23:16):
which is pretty cool. They put like things up in
the sky, or they used sources of radio in the sky.
They saw how those were fuzzed, and then they try
to unfuzzed their signal in the inverse way. So it's
a really clever data analysis just to see this picture
of the magnetic fields between galaxies. Did you say the
project is called Loafer? Yes, it sounds kind of app

(23:38):
for an astronomer, don't you think. I love my astronomy colleague,
and so I will refraining from criticizing their acronyms. But
I guess maybe a question is how strong are these
magnetic fields? Like you know, I know the one here
on Earth is enough to move a compass and deflect
cosmic rays. But how strong is the one in from
the Sun or the galaxy or are the How strong

(23:58):
are these fields that you see between galaxy? These are
not really very strong compared to the kind of things
we feel on Earth or from the Sun. We're talking
a few micro gals, which is a million times weaker
than the Earth's magnetic field. These are really very weak
magnetic field. But you know, there's a lot of space there,
and so if you add them all up, it's a
lot of magnetism, even though it's spread out pretty thin.

(24:22):
All right, I guess the big question then is where
are these magnetic fields coming from? Like, if I'm out
there between galaxies, there's really literally nothing around me, right,
Like there's no rotating black hole or there's no planet
or electrical current, So how could it possibly have a
magnetic field. So let's get into that question, But first

(24:42):
let's take another quick break, all right, Daniel, So space
has a magnetic field. Like if you go out there
in space between galaxies, far from anything and you took
out a compass, it would move, it would point somewhere,

(25:03):
it would point somewhere. Yeah, the space between galaxies has
a magnetic field. And this is something we only recently learned,
like this is the paper from this summer twenty twenty
and kind of mind blowing. And you know, the history
of this research is like, well, let's check over here,
Oh there is a magnetic field. Okay, well let's check
over here. Oh my gosh, there's a magnetic field over
there also. And so we basically never failed to find

(25:26):
a magnetic field wherever we looked, which of course raises
two questions. You know, one is like how far out
does it go if you go out into like the
massive voids in between superclusters where there's just nothing and
nothing from billions of light years? Are there magnetic fields there? Also?
And what could be generating all these magnetic fields. Are
there magnetic fields out there in the middle of nowhere,

(25:47):
So we don't know yet. We've looked out there between
galaxies and we've seen magnetic fields between galaxies, like inside
a galactic cluster, but it's pretty tricky to see things
where there's nothing like. Our strategy or looking for magnetic
fields relies on there being at least some matter there,
some like thin filaments of gas like the ones that
connects galaxies. You know, the space between galaxies isn't totally empty.

(26:11):
There are a few particles there that we can use
to trace the magnetic fields, and the way we talk
about if we're looking deep into the void, it's much
harder to tell if there are magnetic fields there. So
we don't know the answer to that question yet. If
there are magnetic fields deep deep out there in space,
really far from anything in the megavoids. But we have
ideas for how to look for the like there are

(26:32):
no iron filings out there in the middle of nowhere,
so you can't tell that's right. We need to come
up with another technique for measuring those magnetic fields, and
people have ideas, but to me, the big question is like,
what could be making those magnetic fields? Like, what's the
possible source? You mean the ones between galaxies are the
ones in deep space both, right? And it might be
the answer is the same. We have some understanding for

(26:54):
what causes the magnetic field inside the galaxy that we
don't quite know how we got started. We think the
galaxies are powered by the spinning, but between the galaxies,
like what could make those magnetic fields? It's just too big,
too strong, too consistent between the galaxies to be coming
from the galaxies themselves. Could it be like from the
spinning of the galaxies, you know, like galaxies and the

(27:16):
galaxy cluster could be spinning around maybe a common point
and that's what's generating the field. It might contribute, and
also like particles and gas ejected from the galaxies and
all that craziness, But the cluster magnetic fields are too
strong to be explained by all of those Sometimes they're
even stronger than the galactic fields themselves. And also remember

(27:37):
the galaxies take a long time to orbit the galactic center,
and there's all these particles between the galaxies, but those
aren't again, not enough to make these magnetic fields. And
so we really have nowhere to look to to say,
what's created this magnetic field, whereas the dynamo or the
mechanism that's powering this thing. Is there a pattern to

(27:57):
these fields in the inside of the clusters, like to
these fields kind of point everywhere? Is it kind of random?
Or like you know, like if I were out there
in space between galaxies, would my compass go wild or
would it be like I think I know where the
center of the cluster is. Well, we've only begun to
map this out, and we can only see it so
far where there are particles in these very thin filaments

(28:19):
of particles that stretched between the galaxy, So we don't
have a great map yet. We're really only beginning to
explore this, and so what we need is a better
technique to give us a map for where all the
magnetic fields are, even like far away from any of
the galactic clusters, and based on the shape of those
we might get an idea for where it could be
coming from within a cluster, But out out between clusters,

(28:41):
we don't know even if there are magnetic fields. We
know that galaxies have fields and galaxy clusters have fields,
and now we've learned that there are fields between clusters.
But beyond that we don't know. There could be magnetic
fields out there in deep space. We don't know. So far,
everywhere we've looked there have been magnetic fields, all right.
So that's a big mystery. So what could it be.

(29:03):
Where could these magnetic fields come from? Well, nobody really
has a great idea except for this one sort of
super bonker idea which might explain it. And it's a
fun idea because it also sort of solves another puzzle
along the way. And that idea is that magnetic fields
were created all through the universe during the Big Bang,

(29:25):
like when things were hot and nasty and crazy in
the very early universe, when there was just a lot
of energy all around, some of it got dumped into
the magnetic field and it just sort of never went away.
And so this is energy left over in the magnetic
field from the very early moments of the universe and
now it's just stretching through the whole universe. Like maybe

(29:46):
back when the universe was super dense and small, maybe
it had like a spin to it, or it had
a little bit of a magnet effect into it that
then got blown up just like you know, space itself
or the energy of the univer during the Big Bank.
That's right, and today we only can make magnets by
moving electrical charges. But you know, the magnetic field is

(30:07):
just a quantum field. If you can somehow get energy
into it, then that energy can just stick around like
magnetic fields don't decay, they just stay. Like if you
pour energy into a magnetic field, it doesn't necessarily leak
out into another kind of energy. It can just hang out.
And so the question is like, is there some way
in the very early universe for energy to have like

(30:28):
poured into this magnetic field bucket and then just gotten
stuck there. I think you're saying that maybe the universe itself,
the fabric of it, is magnetized. Yes, exactly. That's the
really deep question. And people have always thought like, of course,
not how could you have a universe spanning magnetic field,
But it could be that one was made in very
early times and now it feels all of space, even

(30:50):
where there's nothing, there could be magnetic fields left over
from the Big Bang, And people have been working furiously
on It's called magneto genis on ideas for how in
those very early moments in the universe when there was
energy slashing around and you know, bubbling around, and so
much energy that you couldn't even really think of like
particles being formed. It was just like these hot fields

(31:12):
bouncing around that some of it could have slashed over
into the magnetic field and got stuck there. Wow, NATO genesis. Yeah,
I like how you guys have a need to name it,
you know what I mean. Like somebody was probably writing
a scientific paper and they kept having to write the
phrase where the magnetic field of the universe comes from?
And so they said, you know, let's just give it
a two word, cool sounding name. Oh no, it's one word, man,

(31:34):
It's a single word. Nothing hyphens. It's it's like German.
It's just one long word to describe your idea. All right.
And so the itast and maybe the whole universe has
a magnetic field. Does that mean that maybe you could
use a compass to make your way around the universe? Yeah, exactly.
It could give you like directionality. There could be like
primordial flows and directions just left over from you know,

(31:58):
whatever randomly was happening in that moment it in their
early universe. And and really the only way to tell
is to look where there's nothing, like there's already magnetic
fields out here on Earth, so we can't search for
these like primordial magnetic fields. What we need to do
to look for them is to get really far away
from everything, so far away from any physical source like
moving charge, that the only way to have the magnetic

(32:20):
field would be if space itself had left over magnetic fields.
What you're saying, that's the only way we can tell.
That's the only way we can tell. We have to
remove all the other sources. We have to go into
these voids and look for magnetic fields there between superclusters
of galaxies, far away from any source, because there's nothing
there for us to look at, that's right, And so
there's nothing there to cause magnetic fields in a conventional way.

(32:42):
And so if we find magnetic fields there, then we
can say, oh, they're probably left over from the Big Bang.
So that's really the leftover question is like, are there
magnetic fields deep in the voids of space? Can we
measure them? How can we figure that out? All right?
So I guess the question is how could we figure
that out without going out there? And we can we
have some clever ideas. It's a lot harder. Right, if

(33:03):
you don't have particles that are getting bent and shooting
us radiation, then what you can do is look for
the impact on photons, like photons that fly through these voids.
Photons are magnetic objects right there, wiggles in the electromagnetic field,
and so if they move through a magnetic field, it
changes their polarization. You know how light has different kinds

(33:25):
of polarization and basically like how its phase is spinning
and you can block them with your sunglasses and it
changes when it reflects, etcetera. Well, the photons have this
little like track for how much magnetic field they have
gone through, and so we can look at these photons
and try to understand, like, how is their polarization changed,
because photons they're not bent by magnetic fields, but you're

(33:48):
saying they do sort of aligned to the magnetic field. Yeah, exactly,
they aligned with the magnetic field. And they think that
maybe these voids aren't totally empty. There might be a
few sort of dust grains that get aligned with the
magnetic fields and help support it and it could enhance it,
and that as the photons fly through, they don't change directions,
just changes their polarization. Basically, you can think about like

(34:11):
the photon spinning. We talked about how the electron has
a spin, it can spin up or down. The photon also,
being a quantum particle, has a spin and so it's
spin can change as it flies through these magnetic fields.
This is even harder to do than the low far
measurement that was looking for like characteristic photons from electrons bending.
This is even more subtle and actually can't be done

(34:33):
with low Far. They have to build something totally new
to do this, done with high far, not low far.
They're building in a ray that's an entire square kilometer
dedicated just to radio antennas, and that's gonna be really
good for this measurement. It's called the square kilometer array.
It's gonna come online in T seven and it's gonna
look at photons that have passed through these voids from

(34:54):
you know, galaxies on the other sides of these bubbles
to see if their light is spinning in a way
that tells us whether they there are magnetic fields there.
So it like if you see them all aligne one way,
it would be suspicious, yeah, exactly. Or if you see
patterns or something yeah, if you see patterns, well, we
don't know the directions of those magnetic fields, right. If
the magnetic fields are all aligned, it tells you that

(35:16):
maybe it was made in the early universe during this moment,
or maybe if they're like curved up like a ball
of yarn, it tells you they were made in a
different way. Or if they're all aligned like a corkscrew.
The patterns of those magnetic fields are like a fingerprint
to tell us how and when they were made in
the early universe. So that would be fascinating data. If
you could like know right now the direction of all

(35:37):
the magnetic fields all through the universe, that would tell
us a lot about what happened during the Big Bang, really,
because these fields could be different depending on something that
happened in the Big Bang, Like are there different kinds
of magnetic fields? They're not different kinds of magnetic field,
but depending on how the energy and when the energy
got into the magnetic field, they would arrive in different patterns,

(35:58):
you know, like did it it s law in there
before there were particles or maybe after protons were formed,
or even maybe billions of years later. There are different
mechanisms were sort of getting the energy into the magnetic fields,
and they leave different fingerprints on those magnetic fields. It's
like clues at a crime scene, like a picture. It's
like having a picture of what happened exactly. And you

(36:19):
know that picture of the cosmic microwave background radiation, and
it tells us like where the photons were that came
out of that hot plasma. That pictures so much information
about the nature of that plasma, what was going on
inside it, and how things were bouncing around in it.
We've extracted so much knowledge from that. This would be
like a magnetic equivalent, but it might look back even further.
That plasma we're talking about is like four thousand years

(36:41):
after the beginning of the Big Bang. This magnetic picture
might tell us about things that were happening you know,
milliseconds or nanoseconds afterwards, and so it could be very fascinating,
a big clue about the origin of the universe. Yeah, exactly.
And there's another really fun way that we might be
able to see magnetic fields. We look at these weird
stars called blaze oers. Blazers are stars that have really

(37:05):
high energy gamma rays, and these gamma rays sometimes when
they're flying along through space. Remember they're just high energy photons.
Sometimes they split into an electron and a positron and
then they go back to being in a photon is
a thing that photons do. They sometimes split and then
come back. But electrons and positrons are charged particles, and
so if there's a magnetic field there, then when the

(37:27):
photon splits into the electron and positron, it's more likely
to get broken apart, to separate, to get pulled apart
by the magnetic field, and not recombine if it's going
through a magnetic field to them, if it's going through
a magnetic field exactly. So what we do is we
look at blazeers and that can tell us whether there's
a magnetic field between us and the blaze are. If

(37:49):
we're sort of missing some of the high energy gamma
rays from these blazers, that's suggests that they're basically getting
filtered out by a magnetic field that's between us and them.
It's sort of like magnetic lensing. Wow, I guess that
the overall strategy is, since there's no stuff there is,
to look at how these magnetic fields would affect light itself. Yeah, yeah, light,

(38:12):
that's passing through it will get affected in all sorts
of weird different ways, and that's going to carry information
about where the magnetic fields are. So these are like,
you know, crazy ideas. People are having to answer a
question that ten years ago or twenty years ago people
thought was crazy, you know, like why would you even
worry about magnetic fields and the voids. Well, now it's
a deep and fascinating question. It seems frankly kind of

(38:33):
likely that there are magnetic fields there. I feel like
we have to update now. The Boy Scouts training do
not just include reading a compass and Earth. Now they
should be trained about how to read a compass and space.
What to do if you were lost in a Super Bowl,
you know, be prepared. You never know give up, give
up or give up. You're billions of light years from Earth.

(38:57):
You have no chance. A compass is not going to
save your life. Let's be realistic here, Step one, build
twenty thousand telescopes out of twigs and merit badges. All right, Well,
let's say that they do find a magnetic field of
the universe out there in the voids of space between
galaxy clusters, and let's say it has a pattern. What

(39:18):
what does it mean? What would it tell us about
I don't know what we know about the origins of everything. Well,
it would give us sort of a picture as to
the early universe, which I'm sure could answer all sorts
of questions we can't even imagine asking right now. You
know about how the universe went from like super duper
hot to only just super hot to only just hot,
and all these transitions, and we broke that down in

(39:40):
an episode recently about the first two seconds of the universe.
There are all these transitions where you go from like
too hot to have particles, to be having these kind
of particles, to having those kind of particles, and a
lot of that is just speculations. So it would be
really awesome to have like an image captured from one
of those moments, you know, like an ultrasound to the
whole universe as it was a be You all like

(40:00):
to keep those pictures of when we were hot, for sure,
minor photoshop dea. But also it's a really cool idea
because it solves an outstanding puzzle we have in cosmology.
What's the puzzle? Well, the puzzle is how fast is
the universe expanding? You know, we look out into the universe,
and we see the galaxies are moving away from us,

(40:21):
and that they're moving away from us faster and faster
every year. That's something we call dark energy. This is
the accelerating expansion of the universe, and we use that
to measure something we call the Hubble constant, which tells
us basically, how fast the galaxy is accelerating away from us.
It's like a kilometer per second per millions of light years.
How fast that velocity is increasing, right, because it's changing, right,

(40:45):
the expansion is changing. Yeah. And the interesting thing is
that when you look and you're trying to measure this
rate of expansion, and you measure it today using the
expansion of galaxies and they use clever tricks to try
to measure it in the early universe, you get a
different number. And this is interesting because it tells us like, well,
we don't really know how fast the universe is expanding,
and we don't know if it's expanding at the same

(41:07):
rate now as it was before, or is there more
dark energy than there was before. We had a whole
podcast episode about this, it's called the Hubble tension, like
how fast is the universe expanding? We got two measurements
that disagree. But yeah, they're different by about ten percent,
but that's statistically significant. Like they're two teams are both
pretty confident in their measurements, and so the question is like, well,

(41:30):
what explains it? And you know, one measurement uses the
expansion of the universe, that's the Late Times measurement, and
the other one looks at the very early universe, those
blobs we were talking about in the cosmic microwave background,
and looks at the shapes of those blobs and the
distances between them, and because the speed of the expansion
sort of controls how many blobs you get and how

(41:50):
far apart they are, and they make a measurement. So
it's like the Early Days measurement versus the Late Days measurement,
and they don't quite agree. So maybe they're saying that
there is a universal magnetic field. Maybe that's kind of
where the difference went. Yeah, exactly. The folks who analyzed
their data from the very early universe assumed no magnetic field.
But if you add a magnetic field to the very

(42:13):
early universe, then it turns out you can have a
larger Hubble constant, but it looks smaller and so essentially
they did account for that in their early measurements. And
so if the Hubble constant is actually the one we've
measured in the late universe, it would give you exactly
the picture you see in the early universe if there
was a magnetic field. And so it's sort of like

(42:34):
solves so that it corrects the tension. And it's very
nice way. Now, who would be right then, the late
measurers or the early measurers. Who would get bragging? Right?
I'm sure everyone would find a way to brag, But
this would suggest that the measurement by the expansion team,
the folks who were looking at the actual expansion in
the universe right now, sort of the late measures would
be correct, all right. Well, and coincidentally they're the ones

(42:56):
funding these new experiments. Everybody just wants to know the answer.
But you know, that's exactly what we hope for. When
we do a measurement, two ways that we think should agree.
When we see a discrepancy, we think, well, maybe you
made some silly mistake. But once you've crossed all those
possibilities off, then the other possibility is maybe there's some
new science going on here. We didn't account for maybe

(43:18):
two different set of assumptions. One of them must have
a mistake if the results don't agree. And that's exactly
what we found. And so it's not like anybody screwed
up here. It's just revealed something new about the universe.
And so again this is still an idea, like, we
don't know that there are magnetic fields all through space,
but if there were, it would solve this problem very nicely.

(43:38):
All right, Well, I think it seems like the answer
is stay tuned. The answer is that there are magnetic
fields here on Earth and the Sun and the gaxies
and the galaxy clusters, which is already pretty amazing, but
there might be an even bigger, universe wide cosmic magnetic field. Yeah, exactly.
It's incredible that we keep finding magnetic fields everywhere we look,

(43:59):
despite our ex pectations, and that's pretty fun. It's fun
to see surprises out there in the universe and then
to have to try to explain them to me. That's
much more exciting than finding what you expected. It's finding
what you didn't expect and then having to change your
concept of the universe, bending your concepts to the data itself.
I guess my question, Daniel is that if the universe

(44:19):
has a magnetic field, does that mean it has a
north and a south pole? And would you find a
universal Santa clause in the north pole? That would be
quite a gift. Jokes aside, though, we don't know the
pattern of that magnetic field, and so we don't know
it's orientation if it's totally balanced, so if it's curled
up in all sorts of ways. But that's exactly the
kind of question we'd like to ask. We'd love to
see that picture so we can ask those questions. We

(44:42):
need a special array, like a Santa array to be finally,
the term that all right, well it's it's again. It's
just another one of these crazy measurements and ideas that
tell you that there are invisible things out there in
the universe that we can't immediately see, but are there
and are part of the history and origin of how
things came to be the way they are. That's right,

(45:02):
And so the universe is filled with mystery. So there's
lots of room for your creativity and your curiosity and
vast enigmas waiting to be solved. You just need a
compass to help us find them. Thanks for joining us.
We hope you enjoyed that. See you next time. Thanks

(45:25):
for listening, and remember that Daniel and Jorge explained. The
Universe is a production of I Heart Radio. Or more
podcast from my heart Radio, visit the I Heart Radio
Apple Apple Podcasts, or wherever you listen to your favorite shows.
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Daniel Whiteson

Jorge Cham

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