Avery: Hello, and ah, welcome to Astronomy Daily,
the podcast that brings the cosmos down to
Earth. I'm Avery, and as always, I'm
here with the brilliant Anna.
Anna: Hello, Avery, and hello to all our
listeners. We have a fascinating lineup today
covering everything from cosmic giants
to microscopic survivors.
Avery: That's right. We'll be talking about a major
confirmation of a Stephen Hawking theory.
Moths that survived the vacuum of space.
A telescope on a balloon. A planet that's
orbiting completely off kilter. And we'll end
by tackling one of the biggest questions out
there. Is the universe infinite?
Anna: It's a packed episode.
Shall we start with the giants?
Avery: Let's do it. Our first story is a big
one. Two of the greatest minds in physics,
Stephen Hawking and Albert Einstein,
both had some of their most fundamental
predictions confirmed by a single cosmic
event.
Anna: This involves the collision of two black
holes. Using gravitational wave
observatories, scientists got their clearest
observation yet of such a merger.
Avery: And the first big confirmation relates to
Hawking's area theorem. Um, he predicted that
the surface area of a black hole, its event
horizon can never, ever shrink. It
can only stay the same or grow.
Anna: Right. It's a law of black hole mechanics.
And in this merger, they measured the surface
area of the two original black holes and
compared it to the new, larger one that
formed.
Avery: And?
Anna: And the new surface area was indeed
greater than the sum of the two initial ones.
Hawking was right.
Avery: It's just incredible to see a theoretical
prediction made decades ago proven so
precisely. But that wasn't all they saw, was
it?
Anna: No, it wasn't. The signal was so
clear that they could observe the ring down
of the new black hole. Think of it like
striking a bell.
Avery: Mhm. The ringing.
Anna: Exactly. The new black hole wobbled
and settled into its final shape, sending out
gravitational waves that faded over time,
just like the sound of a bell. The specific
frequencies and decay patterns of that ring
down matched the predictions of Einstein's
general theory of relativity perhaps
perfectly.
Avery: So in one event, we get a check mark for
Hawking and a check mark for Einstein.
And this new object they observed is called a
Kerr black hole, right?
Anna: That's correct. A Kerr black hole is one that
is rotating. Since the two smaller black
holes were spiraling around each other, the
resulting merged black hole inherited that
spin. It's the type of black hole we expect
to be common in the universe.
Avery: Wow. What a powerful confirmation of our
understanding of gravity and the universe.
From the colossal to the well to the very,
very small.
Our next story is almost the polar opposite.
Anna: It really is. This story comes from
the International Space Station, but it's not
about the astronauts inside. It's about
something that was living on the outside.
Avery: On the outside? Fully exposed to space.
Anna: Fully exposed. Scientists placed moss
spores in a container on an external platform
of the iss. For nine months, these
spores endured the vacuum of space,
extreme temperature swings, and the full
force of cosmic radiation.
Avery: That sounds like a recipe for total
destruction. I can't imagine anything
surviving that.
Anna: That's what makes this so astonishing. When
they brought the spores back to Earth, a high
percentage of them were still able to
germinate and grow.
Avery: No way. They just started growing
again after nine.
Anna: Months in raw space as if nothing had
happened. It speaks to the incredible
resilience of life. Organisms like
this, known as extremophiles, really
push the boundaries of what we thought was
possible.
Avery: This has huge implications for theories like
panspermia, doesn't it? The idea that life
could travel between planets on asteroids or
comets.
Anna: It certainly makes it seem more plausible. If
simple spores can survive the harshness of
space for extended periods, it suggests
that the building blocks of life might be
tougher and more widespread than we ever
imagined.
Avery: From survivors in space to a new way of
seeing in space.
Our next story involves a very unusual
observatory. We're not talking about a
mountaintop or a satellite, but a telescope
dangling from a giant balloon.
Anna: This is the Excalibur mission. And while a
balloon might sound low tech, it's actually
an incredibly clever way to do astronomy.
Avery: It carries a telescope up to about
130,000ft, which is above
99% of Earth's atmosphere. This
gives it a much clearer view, especially for
the kind of light it's designed to see. High
energy X rays.
Anna: Mm X rays that are blocked by our
atmosphere. And Excalibur isn't just taking
pictures. Its key function is to measure
the polarization of these X rays.
Avery: Can you break that down for us? What does
measuring polarization actually tell?
Anna: You think of light as a wave.
Usually those waves are oriented randomly.
Polarization is like filtering the light, so
you only see waves oriented in a specific
direction. For astronomers, the. The way X
rays are polarized tells them about the
powerful and complex magnetic fields
near their source.
Avery: So it's a way to map out invisible
magnetic structures. And they pointed this
thing at some pretty famous cosmic objects,
right?
Anna: They did. The mission focused on two
main the Crab Nebula, which is the
remnant of a supernova, and Cygnus
X1, a famous system containing a
black hole that's feeding off a companion
star.
Avery: And by measuring the X ray polarization.
They are getting new insights into the
physics of the neutron star powering the Crab
Nebula and the geometry of the material
swirling into the black hole in Cygnus X1.
It's a whole new layer of information.
Anna: It really is. Balloon based
astronomy provides a fantastic, cost
effective way to get above the atmosphere and
test new technologies.
Okay, from new views to new mysteries,
our next story presents a real puzzle.
Avery: Yeah, this one is a head scratcher.
Astronomers have found an exoplanet system
named TOI 3884
where things just don't add up.
Anna: The planet itself is a super
neptune, larger than Neptune, but smaller
than Saturn. It orbits its star quite
closely. But that's not the strange part. The
strangeness lies in its orbit.
Avery: It's wildly tilted. Most planets
in a solar system form in a flat disk,
so they tend to orbit in the same plane
aligned with the star's equator. This
one is misaligned by about
62 degrees. It's orbiting on
a crazy diagonal path.
Anna: Right. A 62 degree tilt is
extreme. Usually to get an orbit that
tilted, you need a powerful gravitational
nudge from m, another massive object in the
system. Like a giant planet farther out
or a, uh, companion star.
Avery: And the mystery is there isn't one.
Scientists have looked and they can't find
anything massive enough nearby to explain
how this planet got knocked so far off
kilter.
Anna: Precisely. The usual suspects are all
missing. It leaves them with some
unconventional theories. Perhaps the
stars protoplanetary disk was tilted
from the very beginning by a passing star
early in its history. Or maybe there was
another planet that knocked this one aside
and then got ejected from the system
entirely.
Avery: A, uh, cosmic hit and run.
Anna: Exactly.
Avery: And that theory of an ejected planet, A, uh,
cosmic hit and run. Why is that
so difficult to prove?
Anna: Because the getaway car is long gone
and completely invisible. A planet
ejected from its solar system would become a
rogue planet, drifting cold and dark through
interstellar space. There's no star to light
it up. So finding it, let alone tracing
it back to its home system, is practically
impossible with our current technology.
Avery: So scientists have a pretty big mystery.
Anna: On their hands, essentially.
For now, it's an open case file.
It's a reminder that planet formation is a
chaotic and complex process. And
our own solar system systems neat alignment
might be less common than we think.
Avery: Speaking of things being less common than we
think, our final story tackles maybe the
biggest astronomical question of Is
the universe infinite?
Anna: It's a question that feels almost
philosophical, but scientists are trying
to answer it with actual measurements.
The Key lies in determining the overall
shape or geometry of the universe.
Avery: And their best tool for that is the cosmic
microwave background, or cmb.
That's the leftover heat from the Big Bang,
which fills all of space.
Anna: Correct. By studying the tiny
temperature fluctuations in the cmb,
cosmologists can measure the universe's
geometry. There are three basic
possibilities. It could be closed,
like the surface of a sphere, open
like the surface of a saddle, or flat,
like a sheet of paper.
Avery: And so far, every measurement we've made
points to one answer.
Anna: Flat to within a very small
margin of error. The universe appears to be
geometrically flat. If the
universe is truly flat, then in
principle, it would extend infinitely in
all directions.
Avery: Case closed, then, the universe is infinite.
Anna: Not quite. Here's the catch.
We are limited by our observable
horizon. We can only see the part of
the universe from which light has had time to
reach us since the Big Bang.
Avery: The mind just reels at that. If it's truly
infinite, that means that somewhere out
there, an infinite distance away, there's
another solar system exactly like ours, with
another Earth and, and another you and I
having this exact same conversation.
Anna: That's the logical, if unsettling,
conclusion. With an infinite number of
chances, any event with a non zero
probability must occur an infinite
number of times. It pushes the boundaries
of physics into the realm of philosophy.
Avery: Oh, okay, so it's like standing in Kansas. It
looks perfectly flat as far as you can see.
But you know that on a large enough scale,
the Earth is cur.
Anna: That's a perfect analogy. The universe could
be curved on a scale much, much
larger than our observable horizon. It
could be a steer or a saddle so vast
that our little patch of it just looks flat.
Avery: And there's another wrinkle, too, isn't
there? The idea of topology.
Anna: Yes. Even a flat universe
might not be infinite. It could have a
complex topology. For example, it could
be shaped like a donut. If you travel in a
straight line, you eventually end up back
where you started. In that case, the universe
would be flat but finite.
Avery: Have scientists looked for evidence of that
donut shape? For instance, by looking for
repeating patterns in the cosmic microwave
background, as if we were seeing the same
region of space from different directions.
Anna: They have, very carefully. So
far, no such repeating patterns have been
found. While this doesn't rule out a, uh,
finite universe, it does mean that if
the universe is finite, it must be
vastly larger than the part we can see.
So for all practical purposes, it might
as well be infinite from our perspective.
Avery: So in the end we're left without a definitive
answer. Our measurements say flat, which
points towards infinite, but we can't be sure
exactly.
Anna: It's possible that because of the horizon
problem, this is a question we may never
be able to answer for certain. It's one of
the profound limits of cosmology.
Avery: And what a profound place to end our journey
today. From the laws of black holes to the
hardiness of moss, from balloon telescopes to
tilted worlds, and finally to the ultimate
fate and size of the universe itself.
Anna: It really shows you the incredible range of
questions that astronomy seeks to answer.
Thank you all for joining us on, um, this
exploration.
Avery: That's all for this episode of Astronomy
Daily. You can find us wherever you get your
podcasts. And we'll be back next time with
more news from across the universe. Until
then, I'm Avery.
Anna: And I'm Anna. Keep looking up.