Welcome back to Cosmos in a Pod.
Get ready to have your mind blown,
because today we're diving deep into the world of pulsars.
Yeah, these incredible objects, they're basically,
they pack the mass of the sun into something
like the size of a city.
The sun squeezed into a city, that's
like almost impossible to imagine.
Yeah, they're really some of the most extreme
and intriguing objects in the universe.
OK, so tell me what exactly are pulsars.
Well, pulsars are a type of neutron star,
which is what's left after a massive star explodes
in a supernova.
OK.
So imagine a star much bigger than our sun running out
of fuel.
Its core collapses in on itself under the force of gravity,
crushing everything together.
So it's like a cosmic implosion.
Yeah, you could say that.
But how does that turn a star into this super dense object
you're describing?
Right, so during this collapse, the protons and electrons
in the star's core are forced together, forming neutrons,
hence the name neutron star.
Makes sense.
And this creates an object so dense that it's
almost beyond comprehension.
A teaspoon full of neutron star material
would weigh billions of tons.
Billions of tons, that's insane.
OK, so we've got this incredibly dense leftover core of a star.
Is that what makes it a pulsar?
Not quite.
What makes a pulsar special is that it spins incredibly fast
and emits beams of energy from its magnetic poles.
So as the star's core collapses, it also
starts spinning rapidly.
OK.
Think of a figure skater pulling in their arms.
I see.
They spin faster as their mass becomes more concentrated.
Same principle applies here, but on a much grander scale.
So it's like the star is winding up as it collapses.
Right.
And you mentioned something about beams of energy.
Where do those come from?
Well, neutron stars have incredibly
strong magnetic fields, trillions of times stronger
than Earth's magnetic field.
Wow.
These magnetic fields channel charge particles,
causing them to emit radiation from the star's magnetic poles.
We can almost picture it like a giant cosmic lighthouse.
Yeah, exactly.
OK, so we have this super dense spinning star
with beams of radiation shooting out from its poles.
But why do we call them pulsars?
What's so pulsy about them?
Right.
The name pulsar comes from the way we observe them.
Oh.
The magnetic axis of a pulsar is usually
tilted at an angle compared to its rotational axis.
I see.
So as the pulsar spins, these beams of radiation
sweep across space.
OK.
And if Earth happens to be in the path of one of those beams,
we see it as a pulse of radiation.
That makes sense.
So it's not like the beams themselves are pulsing.
It's just that we only see them when they happen
to sweep past Earth.
Right.
It really is like a lighthouse.
But are all pulsars the same?
I imagine they could have different spin rates
and strengths of magnetic fields.
You're absolutely right.
OK.
Pulsars come in a variety of types.
The most common are radio pulsars.
Right.
These emit beams of radio waves, which
we can detect here on Earth using radio telescopes.
So it was radio waves that first gave away
the existence of these pulsars.
That's right.
That's pretty cool.
Yeah.
I'm curious, though, what other kinds of pulsars are there?
Do they all emit radio waves?
Not at all.
OK.
Some pulsars emit X-rays instead of radio waves.
These are called, you guessed it, X-ray pulsars.
Right.
They're typically found in binary systems,
which means they're orbiting around another star.
We had a binary system.
So it's like two stars locked in a cosmic dance orbiting
each other.
Exactly.
Right.
And in the case of X-ray pulsars,
they're pulling material away from their companion star.
Right.
As this material falls onto the pulsar,
it heats up, producing intense X-ray emissions.
So it's like a cosmic X-ray machine
cowered by a stellar diet.
So we've got radio pulsars, X-ray pulsars.
Are there any others?
Well, there's another type that's even more extreme.
Magnetars.
What makes them so extreme?
Magnetars are a rare type of pulsar
with incredibly strong magnetic fields, billions of times
stronger than those of regular pulsars.
Billions.
Wow.
I can't even fathom that.
What makes their magnetic field so powerful?
That's a bit of a mystery.
We still don't fully understand how magnetars get
such intense magnetic fields.
But what we do know is that these magnetic fields produce
powerful bursts of X-rays and gamma rays.
So they're the real powerhouses of the pulsar family.
You could say that.
OK.
And a great example of a magnetar
is the one located in the Crab Nebula.
It's incredibly bright, and astronomers have been studying
it for centuries.
Wait, the Crab Nebula?
Isn't that the rendant of a supernova that exploded
almost 1,000 years ago?
It is indeed.
Wow.
That supernova was so bright that it was visible
during the daytime for weeks.
Really?
And at its center is this incredible magnetar
still spinning and radiating energy
all these centuries later.
That's incredible.
So we've got these cosmic lighthouses,
some emitting radio waves, others blasting out X-rays,
and then we have the superpowered magnetars.
It's mind-blowing to think about these things spinning out
there in space.
But how do scientists even find these pulsars
in the vastness of the cosmos?
Well, it all started with a bit of a surprise, actually.
Back in 1967, a young astronomer named Jocelyn Bell Brunel
was analyzing radio signals from space
when she noticed something peculiar.
What did she find?
Was it aliens?
Not quite.
She detected these incredibly regular pulses of radio waves
so precise that they seemed almost artificial.
At first, they even jokingly called the source LGM-1,
which stood for little green men.
I can see why they might have thought that.
But it turned out to be something even more fascinating.
Exactly.
Further analysis revealed that the signals were coming
from a rapidly rotating neutron star, the first pulsar ever
discovered.
And since then, we've found thousands more, each
with its unique characteristics.
So it was the rhythmic pulses that gave them away.
That's right.
That makes sense.
But here's what I'm really curious about.
Why are pulsars so important?
Why should we care about these crazy spinning stars?
That's a great question.
Pulsars are more than just fascinating objects.
They're incredibly valuable tools for astronomers
and physicists.
For one, they act as natural laboratories
for studying extreme physics.
Extreme physics?
What do you mean by that?
Well, remember how we talked about the incredible density
of neutron stars?
Yeah.
Those conditions are unlike anything
we can create here on Earth.
Right.
They allow us to study how matter behaves
under extreme pressures and densities
and to test our theories about gravity
and fundamental forces.
So pulsars are helping us push the boundaries
of our understanding of the universe.
They are indeed.
And that's just the beginning.
There's so much more to explore.
Well, I can't wait to hear more.
Welcome back to Cosmos in a Pod.
We're continuing our deep dive into the fascinating world
of pulsars.
And I'm still reeling from the fact
that something can be as dense as a teaspoonful of neutron star
material weighing billions of tons.
It is truly mind boggling.
And as we were saying before, pulsars
are not only incredibly dense, but they also
serve as natural laboratories for studying extreme physics.
You mentioned that we can study gravity and fundamental forces
through pulsars.
Can you explain that a little more?
What makes them so useful for that kind of research?
Of course you see the conditions inside a neutron star
are so extreme with gravity crushing matter
to unimaginable densities that they
test the limits of our current understanding of physics.
By observing how matter behaves in these environments,
we can gather insights into the fundamental laws of nature.
OK, so it's like pulsars are giving us
a glimpse into physics at its most extreme, which we could
never replicate here on Earth.
Precisely.
It's like having a front row seat
to a cosmic experiment that's been
running for billions of years.
That's incredible.
Now, before we talked about the idea of using pulsars
for navigation, can you tell me more about that?
How would that even work?
It's a fascinating concept called pulsar navigation.
Imagine you're a spacecraft traveling
vast distances through space.
How do you know where you are?
I guess our current GPS system wouldn't be much help out there.
Exactly.
But pulsars can provide a solution.
OK.
They emit those incredibly regular pulses,
and we know their positions in the sky with great accuracy.
By measuring the arrival times of those pulses
from different pulsars, a spacecraft
could triangulate its position in space,
much like using GPS satellites here on Earth.
So instead of relying on satellites,
we could use these spinning stars as cosmic beacons
to guide us across the galaxy.
That's amazing.
It's still a relatively new field of research,
but it holds immense potential for the future of space
exploration, especially for missions
venturing beyond our solar system,
where traditional navigation methods become less reliable.
It's mind-boggling to think that we might one day
be using pulsars to chart our course through the stars.
Now, I have to admit, I'm still struggling
to wrap my head around those millisecond pulsars, the ones
that spin hundreds of times per second.
How do they get to be so fast?
Yes.
The speed demons of the pulsar world,
their incredible spin rates, are thought
to be the result of a process called accretion.
Accretion.
I'm not familiar with that term.
Can you break it down for me?
Certainly, accretion happens when a pulsar
is in a binary system with a companion star,
just like we discussed with X-ray pulsars.
The pulsar's strong gravity pulls material
from its companion, and as this material spirals inward,
it transfers angular momentum to the pulsar, causing
it to spin faster and faster.
So it was like a spinning top being whipped up
by the inflowing matter.
A very apt analogy, and over millions of years,
this process can spin a pulsar up to those incredible speeds,
sometimes even reaching thousands
of rotations per second.
That's just phenomenal.
I remember you mentioned that these millisecond pulsars are
also incredibly precise timekeepers.
That's right.
Their rotational periods are so stable
that they rival atomic clocks here on Earth.
We're talking about variations of just a few microseconds
over many years.
Wow, so what can we do with such precise cosmic clocks?
Their precision makes them invaluable tools
for a wide range of scientific research, for instance.
We can use them to test fundamental physical theories,
like Einstein's theory of general relativity.
General relativity, the theory about gravity
and the curvature of spacetime.
How do pulsars help us with that?
Well, according to general relativity,
massive objects like pulsars should
warp spacetime around them.
And this warping should affect the way light travels near them
by carefully measuring the timing of pulsar signals
as they pass through the gravitational field
of a companion star.
We can detect these subtle effects
and confirm the predictions of general relativity.
So pulsars are not only helping us
understand the extreme conditions inside neutron
stars, but they're also allowing us
to test some of the most fundamental theories
in physics.
That's just amazing.
Indeed.
And there's more millisecond pulsars can also be used
to detect gravitational waves.
Wait, gravitational waves?
Those ripples in spacetime caused by cataclysmic events,
like black hole collisions.
How can we use pulsars to detect something like that?
It's a fascinating technique called pulsar timing arrays.
By monitoring a network of millisecond pulsars
spread across the sky, astronomers
can look for tiny variations in the arrival
times of their pulses.
And those variations are caused by gravitational waves passing
between us and the pulsars, like the ripples
distorting the signal.
Exactly.
Imagine a gravitational wave passing
through the space between us and a distant pulsar.
As the wave stretches and squeezes spacetime,
it slightly alters the distance the pulse has to travel,
causing it to arrive a tiny bit earlier or later than expected.
So by carefully measuring those tiny timing differences
across multiple pulsars, we can actually
detect these gravitational waves from billions
of light years away.
Precisely.
It's like having a giant cosmic detector with pulsars
spread across the galaxy acting as our sensors.
This is also mind blowing.
I knew pulsars were fascinating, but I had no idea
they played such a crucial role in so many areas
of astronomy and physics.
And we've only just scratched the surface,
despite decades of research, pulsars still
hold many mysteries.
Oh.
Like what?
You've piqued my curiosity.
What are some of the unanswered questions
that scientists are still grappling with?
Well, for one, we're still not entirely sure what determines
the lifespan of a pulsar.
We know that they slow down over time as they lose energy,
but the exact mechanisms and timescales involved
are still being debated.
So eventually, even these rapidly spinning pulsars
will eventually fade away.
In a sense, yes, but we're not sure how long this process
takes or what the final fate of a pulsar might be.
Fascinating.
Are there any other mysteries surrounding pulsars
that you find particularly intriguing?
Another big question is, what happens when pulsars merge?
We know that binary pulsars can eventually
spiral in towards each other and collide,
but the details of those mergers are still largely unknown.
What do you think might happen?
Do they create something even more exotic?
We believe that these mergers could produce even more
extreme objects, potentially giving birth to black holes
or other phenomena we haven't even imagined yet.
That's incredible.
So there's still so much we don't
know about these cosmic wonders.
Absolutely.
And that's what makes pulsar research so exciting.
Every new discovery opens up new avenues of exploration
and deepens our understanding of the universe.
This has been an incredible journey so far.
I'm eager to hear what else you have
to share about these amazing objects.
Shall we continue our exploration?
Let's dive into the final part of our pulsar deep dive.
We'll uncover even more fascinating details
about their impact on our understanding of the cosmos.
Welcome back to Cosmos in a Pod.
We're on the final leg of our deep dive
into the world of pulsars.
And I have to say, I'm feeling a sense of awe
at these tiny yet incredibly powerful objects.
Yeah, they are truly remarkable, aren't they?
And as we've been discussing, pulsars
are not just fascinating in their own right.
They're also incredibly valuable tools
for astronomers and physicists.
Exactly.
We've talked about how they help us study extreme physics,
test fundamental theories, and even potentially navigate
through space.
But you mentioned before another amazing application,
using pulsars to detect gravitational waves.
I'm dying to hear more about that.
Yes, it's one of the most exciting areas of research
in modern astronomy.
You see those millisecond pulsars
with their incredibly precise timing
can act like cosmic clocks, helping us detect
these ripples in spacetime.
OK, I'm trying to picture this.
How do we actually use pulsars to detect something
as subtle as a gravitational wave?
Imagine you have a network of these millisecond pulsars
spread across the sky, each one pulsing
with incredible regularity.
Astronomers carefully monitor the arrival times
of these pulses here on Earth.
So it's like having a giant web of cosmic clocks
all synchronized and ticking away with incredible accuracy.
Precisely.
Now imagine a gravitational wave generated
by a cataclysmic event, like the merger
of two supermassive black holes, passes through this network
of pulsars.
What happens to the pulsar signals
when that wave passes through?
As the wave stretches and squeezes spacetime,
it very slightly alters the distance
the pulses have to travel to reach us.
This causes some pulses to arrive a tiny bit earlier
than expected, while others arrive slightly later.
So the gravitational wave leaves a sort of fingerprint
on the timing of the pulsar signals.
Exactly.
By analyzing these tiny variations in pulsar arrival
times across the entire network of pulsars,
astronomers can detect the presence
of the gravitational wave and even determine
its direction and strength.
Wow, that's incredible.
It's like using these tiny spinning stars
to listen to the symphony of the universe,
detecting the echoes of these colossal events that
happened billions of years ago and billions of light years
away.
It is a symphony of sorts, a symphony of spacetime itself.
And it's only possible because of the incredible precision
of those millisecond pulsars.
It's mind blowing.
And what kind of information can we
learn from these gravitational waves?
What did they tell us about the universe?
They open a whole new window into the cosmos,
revealing events and objects that
are otherwise invisible to traditional telescopes,
for instance.
They can tell us about the mergers of supermassive black
holes at the centers of galaxies.
I remember you mentioned those earlier black holes millions
or even billions of times the mass of our sun.
Those collisions must be unimaginably powerful.
They are indeed.
And by studying the gravitational waves
from these events, we can learn about the masses spins
and even the environments of those black holes.
So it's not just about detecting the waves.
It's about using them to probe the most extreme
and mysterious objects in the universe.
Exactly.
And it goes beyond black holes.
Gravitational waves can also tell us
about the early universe just moments after the Big Bang.
They carry information about the conditions
that existed when the universe was just
a fraction of a second old.
Wow, so pulsars are not only helping us
understand the present universe, they're
also giving us glimpses into its very beginnings.
That's truly remarkable.
It is.
And it highlights just how interconnected everything
in the cosmos is.
These tiny spinning stars born from the deaths of massive stars
can help us unravel the secrets of the largest structures
and most ancient events in the universe.
It's an incredible testament to the power
of scientific ingenuity using these cosmic lighthouses
to illuminate the darkest corners of the universe.
Indeed.
And as we continue to refine our techniques
and build even more sensitive detectors,
who knows what other wonders we might uncover
using these amazing objects.
I, for one, can't wait to find out.
This deep dive into the world of pulsars
has been an incredible journey filled
with mind-boggling concepts and breathtaking discoveries.
It has been a pleasure exploring these wonders with you.
And for all of you listening out there,
be sure to follow and subscribe to Cosmos in a Pod's podcast
and YouTube channel for more fascinating insights
into space and science.