Avery: Welcome to Astronomy Daily, the podcast that
brings the cosmos down to Earth. I'm Avery.
Anna: And I'm Anna. It's great to be with you
today. We've got a fantastic lineup. We're
starting with our own sun, which just put on
a spectacular and slightly terrifying
show for our most powerful solar telescope.
Avery: Then we're heading into our own atmosphere,
to a mysterious layer we can barely reach.
And the brilliant new technology that might
finally unlock its secrets. After that, we'll
dig deep into Mars to find out why its
insides are as chunky as a cookie.
Anna: And finally, we'll tackle the big one, time
travel. A new study suggests it might be
possible, but it comes with a catch that
changes everything. So let's get started.
Avery: Alright, Anna, let's talk about the sun. We
know it can be violent, but this is something
else. The NSF Inouye Solar
telescope just got its first look at an X
class flare. And the images are mind
blowing.
Anna: They really are. For our listeners, an X
class flare is the most powerful category of
solar flare there is. These are massive
explosions of energy and catching one with
this level of detail is a huge deal. The
telescope managed to capture it at a
resolution where the smallest details are
just four Earths across.
Avery: That's incredible. It's like having a super
powered magnifying glass on, um, the most
energetic event in our solar system.
So what did they actually see with this new
level of clarity?
Anna: They saw something called coronal loops, but
on a scale we've never seen before. These are
thin filaments of plasma that arch over the
sun's surface following magnetic field lines.
We've seen bundles of them before. But
Inoue's power allowed scientists to see
individual loops for the first time. Some
of these loops were as small as 21 kilometres
wide, which is right at the telescope's
resolution limit. It's these magnetic field
lines twisting, snapping and reconnecting
that powers the solar flares in the first
place.
Avery: So saying the fundamental building blocks of
these events is a game changer. I know these
flares can be dangerous, knocking out radio
communications and power grids here on Earth.
Does this help us prepare for that?
Anna: That's the goal. According to the
researchers, peering into these smaller
scales where the magnetic reconnection
actually happens, opens the door to
understanding the engine behind the flares.
Better understanding leads to better
prediction models, which gives us a better
chance to protect our technology. When the
sun decides to act, it's a huge step
forward in forecasting space weather.
Avery: From the very big to the very,
very small.
Our next Story is about exploring a part of
our own atmosphere that's been stubbornly out
of reach. The mesosphere. It's too high for
balloons, but too low for satellites.
Anna: Exactly. It's a huge blind spot for
climate and weather data. But researchers at
Harvard and the University of Chicago may
have found a way to reach it. And it sounds
like something out of science fiction.
They've designed ultralight flying structures
that float by harnessing sunlight itself.
No engines, no fuel, powered by
sunlight.
Avery: How does that work?
Anna: It uses a phenomenon called photoforces.
It's a gentle force that pushes on an object
when light heats one side more than the
other. Down here on the ground, the force is
so weak, we never notice it. But in the
extremely thin air of the mesosphere, that
tiny push is enough to overcome the weight of
these new structures.
Avery: So, so what are these things made of? They
must be unbelievably light.
Anna: They are. They're built from ultra thin
ceramic alumina with a special coating on the
bottom to absorb sunlight. The researchers
actually tested them in a lab in a low
pressure chamber that mimics the mesosphere.
And they levitated perfectly with just a bit
of light.
Avery: That's amazing. The applications seem
endless. You could attach sensors for climate
data or create floating communication arrays
like a, uh, low orbit starlink. One of the
researchers even said they could eventually
fly on Mars.
Anna: That's the long term vision. Mars has a thin
atmosphere that's very similar to our
mesosphere, making it a perfect target.
One of the lead authors called it the Wild
west in terms of applied physics, because
nothing has ever been able to fly sustainably
up there before. This opens up an
entirely new way to explore our upper
atmosphere and potentially other
worlds too.
Speaking of Mars, our next story takes
us deep inside the red planet. A
new analysis has revealed that the
interior of Mars is, and this is
a direct quote, as chunky as a
delicious macadamia cookie.
Avery: I love it when scientists get creative with
their analogies. So what does that mean
exactly? It's not actually made of cookies, I
assume.
Anna: No. Unfortunately, what they found
using data from the Insight lander is
that huge chunks of Mars
ancient early crust are preserved
deep within its mantle. These are
geological fossils from when the planet was
first forming four and a half billion years
ago.
Avery: Insight was the mission that listened for
Marsquakes. Right. So they used seismic waves
to map the interior. Like an ultrasound.
Anna: That's right. By studying how the waves from
these quakes travelled and bounced, they
couldn't map out the Composition. And they
found these massive fragments, some up
to four kilometres across, just drifting in
the mantle. The theory is that during the
chaotic early days of the solar system,
giant impacts shattered the young planet's
crust and those pieces sank into the
molten mantle before a new crust formed.
Avery: And they've just been sitting there ever
since?
Anna: Pretty much. Unlike Earth, Mars doesn't
have active plate tectonics. Our crust and
mantle are constantly churning and recycling
each other. Mars has a single
solid crust, a stagnant lid.
So its interior evolution is much slower.
It's acted like a, uh, time capsule,
preserving this evidence of its violent
birth. This gives us an incredible
window into what rocky planets look like
before tectonics get started.
Avery: Okay, for our final story, we're going from
planetary history to rewriting it. Or
maybe not.
Anna, uh, let's talk time travel.
Anna: This is a really fascinating one. A new
study looked at what would happen inside a
spaceship travelling on a closed time
like curve, which is basically a loop through
space time that brings you back to the exact
moment you left.
Avery: The classic sci fi setup. So do we get to go
back and fix our mistakes or accidentally
erase ourselves from existence by bumping
into our grandfather?
Anna: Well, according to this research, neither.
The study uses standard quantum mechanics
and thermodynamics, not some exotic new
theory. And the conclusion is
the laws of physics themselves demand
self consistency. After one full
loop, everything inside the ship clocks
computers, and even you must return
to its original state.
Avery: So time travel would be like pressing a
cosmic reset button.
Anna: Precisely. And it gets weirder.
To maintain that consistency, the second law
of thermodynamics, the one that says
disorder or entropy always increases,
has to be temporarily reversed. At a
certain point in the loop, entropy hits a
maximum and then it starts decreasing.
Processes run backwards. Coffee would get
warmer, broken eggs would reassemble.
Avery: And what does that do to a person? What about
our memories?
Anna: This is the biggest catch. The formation of
memory is a thermodynamic process,
as entropy reverses to bring the system back
to its starting state. Any memories you
formed during the trip would have to be
erased completely.
Avery: So you could live through this incredible
journey. But from your point of view, it
would feel like nothing happened at all.
You'd get in the ship, complete the loop, and
arrive back in the same instant. With no
memory of the trip.
Anna: Exactly. It's the ultimate form of what
happens in the loop stays in the loop because
it gets completely wiped clean. So instead
of rewriting history, you just reset
it and forget it. A very different and
much less adventurous picture of time travel
than the movies suggest.
Avery: And that's all the time we have for today,
from the fiery heart of the sun to the
delicate flyers in our atmosphere, the chunky
interior of Mars, and the strange,
forgettable physics of time travel.
Anna: Thanks for joining us on Astronomy Daily. If
you'd like to stay on top of the latest space
and astronomy news, simply visit our website
at astronomydaily IO and
check out our constantly updating newsfeed.
You can also find all our back episodes
there. If you'd like to do some binge
listening, I'm Anna.
Avery: And I'm Avery. We'll see you next time for
another look at our amazing universe. Until
then, keep looking up.