March 19, 2025 • 26 mins
This engaging exploration of black holes takes listeners on a cosmic journey through the most mysterious objects in our universe. Host Felix Mercer explains the anatomy of these cosmic devourers with his signature blend of scientific accuracy and storytelling magic. From the point-of-no-return event horizon to the infinitely dense singularity at the core, from the swirling accretion disks to the different varieties of black holes that populate our cosmos, this episode makes complex astrophysics accessible and fascinating. For more mind-expanding content like this, visit https://www.quietperiodplease.com/ where you'll find a universe of engaging podcasts waiting to expand your horizons.
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:00):
Welcome to Cosmic Curiosities, where we journey through the most
fascinating phenomena in our universe. I'm your host, Felix Mercer,
and today we're diving into the mysterious realm of black holes,
those cosmic devourers that bend the very fabric of space
and time. This is episode forty two of our ongoing
(00:22):
exploration of the Universe's greatest puzzles, brought to you by
the Quiet Please Podcast Network. So dim the lights, settle in,
and let's fall into the unfathomable depths of these cosmic
enigmas together. Imagine, if you will, standing at the edge
of a cliff. But this isn't just any cliff. It's
(00:45):
a cliff in space, one where the rules we take
for granted start to unravel like a poorly knitted sweater.
The wind doesn't just blow here, it pulls, and below
you isn't solid ground, but a darkness so complete it
seems to swallow light itself. This, my curious friends, is
(01:06):
the neighborhood of a black hole, perhaps the most misunderstood
and fascinating object in our cosmic backyard. I've always found
it delightfully ironic that some of the brightest minds in
human history have dedicated their lives to studying these darkest
objects in the universe. Black Holes are cosmic contradictions. They're
(01:29):
simultaneously simple and complex, empty yet full, Theoretically sound yet
observationally elusive. They're the universe's ultimate magicians, making things disappear
without a trace, or so it seems. But today we're
going to peek behind the curtain of this cosmic magic show.
(01:52):
The story of black holes begins, as many good stories do,
with a thought experiment. Back in seventeen eighty, a fellow
named John Michelle, a geologist and astronomer with a particularly
vivid imagination, wondered what would happen if a star became
so dense that its escape velocity exceeded the speed of light.
(02:16):
He called these hypothetical objects dark stars. A few years later,
Pierre Simone la Place independently came to similar conclusions. Both
men were essentially describing what we now call black holes,
though neither had Einstein's theories of relativity to fully explain
the phenomenon. Fast forward to nineteen fifteen, when Albert Einstein
(02:40):
published his General Theory of Relativity, providing the mathematical framework
that would later be used to predict and describe black holes,
but Einstein himself was skeptical about their existence, believing them
to be mathematical curiosities rather than real astronomical objects. It
wasn't until nineteen sixty seven that astronomer John Wheeler coined
(03:03):
the term black hole, giving these cosmic phantoms the evocative
name we use today. Now, before we plunge headlong into
the depths of these cosmic devourers, let's establish what exactly
a black hole is in the simplest terms, though nothing
about black holes is truly simple. A black hole is
(03:25):
a region of space time where gravity is so intense
that nothing, not even light, can escape once it passes
a certain boundary. This boundary is what we call the
event horizon, which is a fancy way of saying the
point of no return. Imagine your canoeing down a river
that gradually becomes faster and more turbulent until it eventually
(03:47):
cascades over a waterfall. As you paddle along, there comes
a point where, no matter how hard you paddle in
the opposite direction, the current is too strong to overcome
that point. That critical threshold is analogous to the event
horizon of a black hole. Once you cross it, the
(04:08):
only way to go is down. The event horizon isn't
a physical surface you can touch or see. It's a
mathematical boundary, a point of no escape. If you were
unfortunate enough to cross this threshold, you wouldn't immediately notice
anything unusual. In fact, according to the laws of physics
(04:29):
as we understand them, you wouldn't feel any sudden jolt
or change as you cross the event horizon. This is
one of the many counterintuitive aspects of black holes. The
event horizon is less like a wall and more like
an invisible line of demarcation. But here's where things get
(04:49):
truly strange. From the perspective of someone watching you from
a safe distance, they would never actually see you cross
the event horizon. As you you approach it, the light
coming from you would be increasingly red shifted, stretched to
longer wavelengths by the intense gravitational field. Time itself would
(05:10):
appear to slow down from their perspective, and your image
would fade and freeze, creating what some physicists poetically call
a ghostly afterglow at the edge of the black hole.
This time dilation effect is a direct consequence of Einstein's relativity,
which tells us that gravity doesn't just pull on mass,
(05:31):
it pulls on the very fabric of space time. Near
a black hole, space time is so severely warped that
our intuitive understanding of time simply breaks down. If you
were wearing a watch as you fell into a black hole,
someone observing from afar would see your watch ticking more
and more slowly, eventually appearing to stop altogether as you
(05:54):
approach the event horizon. From your perspective, though, your watch
would tick along normally, and you'd cross the event horizon
without noticing this particular threshold. Of course, you would notice
other things, the gravitational tidal forces. The difference in gravitational
pull between different parts of your body would become increasingly
(06:16):
severe as you approach a black hole. For smaller black holes,
these tidal forces would become lethal long before you reach
the event horizon, stretching you vertically and compressing you horizontally
in a process delightfully termed spaghettification by physicists. I've always
(06:37):
thought that term adds a touch of culinary humor to
what would otherwise be a rather grim cosmic demise. For
supermassive black holes like the one lurking at the center
of our Milky Way galaxy, a monster named Sagittarius, aie
that weighs in at about four point three million times
(06:58):
the mass of our Sun. The tidal forces at the
event horizon would actually be much less severe. You might
survive crossing the event horizon at least momentarily before the
increasingly intense forces deeper inside would inevitably tear you apart.
It's a small comfort, I suppose, But when dealing with
(07:20):
black holes, we take our comforts where we can find them.
Once past the event horizon, all paths lead inexorably toward
the center of the black hole, toward what physicists call
the singularity. This is where our current physics breaks down
in a magnificent mathematical tantrum. According to general relativity, the
(07:41):
singularity is a point of infinite density and zero volume,
where spacetime curvature becomes infinite. It's a bit like dividing
by zero and mathematics you get a nonsensical answer that
suggests you've pushed your mathematical framework beyond its limits of applicability.
Many physicists suspect that the prediction of a true singularity
(08:05):
is a sign that general relativity is incomplete, not that
such infinities actually exist in nature. Quantum mechanics are other
great physical theory simply doesn't play nicely with general relativity
when it comes to describing what happens at the singularity.
This incompatibility has led to decades of research into quantum
(08:28):
gravity attempts to reconcile these two fundamental theories into a
more comprehensive understanding of the universe. Some approaches, like string
theory and loop quantum gravity, suggest that what we perceive
as a singularity might actually be something more complex and
less mathematically problematic. Perhaps the singularity is a densely packed
(08:52):
not of space time, or maybe it's a portal to
another universe entirely a cosmic escape hatch through a wormhole.
The honest truth is that we simply don't know, and
that's what makes this frontier of physics so exhilarating. We're
standing at the edge of human knowledge, peering into the abyss,
(09:12):
and the abyss is staring right back. While the event
horizon and singularity make up the basic anatomy of a
black hole, there's another feature that makes them visible to
us despite their light trapping nature. The accretion disc this
is the cosmic dinner plate from which a black hole
feeds a swirling maelstrom of gas, dust, and other matter
(09:37):
spiraling inexorably toward the event horizon. As matter in the
accretion disc orbits closer and closer to the black hole,
it speeds up and heats up due to friction and compression.
This superheated material can reach temperatures of millions of degrees,
causing it to emit radiation across the electromagnetic specectrum, from
(10:01):
radio waves to visible light to X rays. It's this
radiation that allows us to detect black holes indirectly, even
though the black holes themselves emit no light. The inner
edge of the accretion disk, just outside the event horizon,
is one of the most violent places in the universe. Here,
(10:22):
matter orbits at a significant fraction of the speed of light,
and the extreme conditions can cause jets of particles to
be ejected along the black hole's axis of rotation, sometimes
extending for thousands of light years. These jets are among
the most energetic phenomena in the universe, and they can
(10:43):
have profound effects on their surrounding environments, influencing the evolution
of entire galaxies. The accretion disc isn't just a feeder
mechanism for the black hole. It's also a cosmic laboratory
for testing physics under extreme can The inner regions of
these disks experience gravitational fields and velocities far beyond anything
(11:08):
we can replicate in terrestrial laboratories. By studying the radiation
from these regions, astronomers can test the predictions of general
relativity and other physical theories and environments where the effects
are pronounced and unmistakable. One particularly fascinating aspect of accretion
disks is their role in what we call active galactic nuclei.
(11:32):
These are the extraordinarily luminous central regions of some galaxies
powered by supermassive black holes actively consuming matter at prodigious rates.
The energy released in this process can outshine all the
stars in the host galaxy combined, making these active nuclei
visible across vast cosmic distances. Quasars, the most extreme examples
(11:58):
of active galactic nuclear are among the most distant and
energetic objects we can observe in the universe, with some
emitting the equivalent of trillions of suns now, not all
black holes are created equal. Based on their mass, astronomers
classify them into several categories, each with its own origin, story,
(12:22):
and cosmic significance. Stellar mass black holes, weighing in it
about five to several tens of solar masses are the
most common type. These form from the catastrophic collapse of
massive stars at the end of their lives. When a
star at least twenty times the mass of our Sun
(12:43):
exhausts its nuclear fuel, the outward pressure that had been
holding it up against gravity suddenly vanishes. The core collapses,
triggering a supernova explosion that blows off the outer layers
of the star. If the remaining core is massive enough,
generally more than about three solar masses, not even neutron
(13:04):
degeneracy pressure can halt the collapse, and a black hole
is born. These stellar mass black holes are the cosmic middleweights,
heavy enough to warp spacetime dramatically, but still relatively modest
on the cosmic scale. They are also the type that's
been most directly observed through their effects on companion stars
(13:26):
and binary systems. When a black hole orbits a normal star,
it can pull matter from the star, forming an accretion
disc that betrays the black hole's presence through its X
ray emissions. At the other end of the scale are
the supermassive black holes, the true heavyweights of the cosmic arena.
(13:48):
These behemoths can weigh millions or even billions of times
the mass of our Sun, and they reside at the
centers of most, if not all, large galaxies, including our
own Milky Way. The exact mechanism by which these gigantic
black holes form remains one of the great unsolved mysteries
(14:10):
in astronomy. One theory suggests that they grew from smaller
seed black holes, gradually accumulating mass by consuming gas, dust, stars,
and even other black holes over billions of years. Another
possibility is that they form directly from the collapse of
enormous clouds of gas during the early universe, bypassing the
(14:34):
stellar mass black hole stage entirely. Or perhaps it's a
combination of these processes, with the exact recipe varying from
galaxy to galaxy. What we do know is that supermassive
black holes have a profound influence on their host galaxies.
There's a remarkable correlation between the mass of a supermassive
(14:55):
black hole and various properties of its host galaxies bulge,
suggesting a coevolutionary relationship. The black hole, despite being tiny
compared to the galaxy as a whole, like a p
at the center of a sports stadium, somehow communicates with
and influences the development of the entire galaxy. This influence
(15:19):
likely occurs through the feedback effects of the black hole's
feeding process, as the energy released from the accretion disc
and jets can heat or even expel gas from the galaxy,
regulating star formation and galactic growth. Bridging the gap between
stellar mass and supermassive black holes are the intermediate mass
(15:41):
black holes, weighing in at hundreds to tens of thousands
of solar masses. These middleweight champions have been the most
elusive category, with evidence for their existence only recently becoming compelling.
Some ultra luminous X ray sources in nearby galaxies are
thought to be powered by intermediate mass black holes, and
(16:03):
there's evidence suggesting they might reside at the centers of
some globular clusters, dense conglomerations of ancient stars that orbit
galaxies like satellites. The origin of intermediate mass black holes
is still debated. They might form from the collisions and
mergers of multiple stellar mass black holes and dense star clusters,
(16:26):
or they could be the remnants of special types of
very massive stars that existed in the early universe. Some
might even be failed supermassive black holes seeds that began
growing but never reached the gigantic proportions of their more
successful counterparts. Understanding intermediate mass black holes is crucial for
(16:50):
filling in the evolutionary picture of black holes across cosmic time.
They could represent an important stepping stone in the growth
of supermassive black holes, and their study might help resolve
questions about how the cosmic heavyweights at the centers of
galaxies formed and evolved. A relatively recent addition to our
(17:11):
understanding of black holes came in twenty fifteen, when the
Laser Interferometer Gravitational Wave Observatory LIGO detected gravitational waves from
the merger of two black holes. This groundbreaking observation not
only confirmed a major prediction of Einstein's general relativity, but
(17:32):
also opened a new window for observing black holes. Through
gravitational waves, we can hear black holes colliding, providing information
that's complementary to what we learn from electromagnetic observations. The
LIGO detections have revealed a population of black holes in
the twenty to one hundred solar mass range, some of
(17:53):
which are heavier than what standard stellar evolution models had predicted.
This has led to new questions and theories about how
black holes form and evolve, including the possibility of hierarchical mergers,
where black holes that are themselves the products of previous
mergers combined to form increasingly massive objects. In twenty nineteen,
(18:17):
the event Horizon telescope collaboration gave us the first direct
image of a black hole's shadow, the dark silhouette cast
against the bright background of the accretion disc. This landmark
achievement focused on the supermassive black hole at the center
of the galaxy, and eighty seven provided a stunning visual
(18:38):
conformation of these extraordinary objects. The image shows a bright
ring of emission from the accretion disc, with a central
dark region corresponding to the shadow cast by the black hole,
a region about two point five times larger than the
event horizon itself due to the bending of light around
(19:00):
on the black hole. This image was followed in twenty
twenty two by a similar picture of Sagittarius, a star
the supermassive black hole at the center of our own
Milky Way galaxy. These images have not only captured the
public imagination, but have also provided valuable scientific data, allowing
(19:21):
astronomers to test the predictions of general relativity under the
most extreme conditions. Black Holes aren't just passive cosmic objects,
their dynamic entities that can change and evolve. When black
holes merge, they release an enormous amount of energy in
the form of gravitational waves ripples in the fabric of
(19:44):
space time that propagate outward at the speed of light.
The energy released in these mergers can be astounding. In
a typical black hole merger detected by LIGO, several solar
masses worth of energy are converted into gravitational radiation in
a fraction of a second, temporarily outshining the entire visible
(20:06):
universe and gravitational wave luminosity. Black Holes can also spin,
carrying angular momentum inherited from the matter that formed them
or fell into them. A spinning black hole drags the
fabric of space time around it in a process called
frame dragging, creating a region outside the event horizon called
(20:28):
the ergosphere. Within this region, it's impossible to remain stationary
with respect to distant stars. Space itself is rotating. This
spinning also affects the shape of the event horizon, causing
it to bulge outward at the equator, a phenomenon known
as the care geometry, named after mathematician Roy Kerr, who
(20:53):
found the solution to Einstein's equations for rotating black holes.
The spin of a black hole has profound implications for
its interactions with the surrounding environment, affecting the efficiency with
which it can convert matter into energy, and the structure
of the accretion disc and jets. Astronomers can measure black
(21:14):
hole spin by carefully analyzing the X ray emission from
the inner edge of the accretion disc, where the effects
of spin are most pronounced. One of the most mind
bending aspects of black hole physics involves what happens to
the information that falls into them. According to quantum mechanics,
(21:35):
information cannot be destroyed the complete data about the state
of a physical system must be preserved, even if transformed.
But black holes seem to destroy information, reducing everything that
falls into them to just three properties mass, charge and spin,
(21:55):
a principle known as the no hair theorem. This a
contradiction between quantum mechanics and general relativity has led to
the black hole information paradox, a problem that has vexed
physicists for decades. Stephen Hawking's discovery that black holes should
emit radiation due to quantum effects, now known as Hawking radiation,
(22:20):
only deepened the paradox. This radiation causes black holes to
slowly evaporate over mind bogglingly long time scales, but it
appears to be purely thermal, carrying no information about what
fell into the black hole. Various solutions to this paradox
have been proposed, from the idea that information is stored
(22:42):
in subtle correlations within the Hawking radiation to more exotic
possibilities like information being stored in a firewall at the
event horizon or in microscopic structures at the plankion level.
Some theories even suggest that information isn't true lost, but
is transferred to baby universes that butt off from our own,
(23:05):
or that it's stored in a holographic manner on the
event horizon. The resolution to this paradox will likely require
a full theory of quantum gravity, unifying our understanding of
the quantum world with Einstein's description of gravity. It remains
one of the most profound challenges in theoretical physics, sitting
(23:27):
at the intersection of general relativity, quantum mechanics, and thermodynamics.
Black holes also feature prominently in speculative but mathematically grounded
concepts like wormholes, hypothetical tunnels through spacetime that could potentially
connect distant regions of the universe or even different universes entirely.
(23:49):
While traversible wormholes remain firmly in the realm of theoretical
physics with significant obstacles to their practical realization, they highlight
the rich and strange possibilities that emerge when we push
our understanding of gravity to its limits. As we've journeyed
through the anatomy of black holes, from the event horizon
(24:11):
to the singularity, from the accretion disc to the various
types that populate our universe, I hope you've gained a
sense of why these objects captivate both scientists and the
public imagination. They are cosmic laboratories where the laws of
physics are pushed to their breaking points, revealing the cracks
in our understanding and pointing the way toward deeper truths.
(24:35):
Black holes remind us that the universe is not just
stranger than we imagine, but stranger than we can imagine.
They challenge our intuitions about space, time, and the nature
of reality itself. In their unfathomable depths lie some of
the most profound questions in physics, questions that may ultimately
(24:56):
lead us to a more complete understanding of the cosmos
and our place within it. As we continue to observe
these cosmic enigmas with increasingly sophisticated tools, from gravitational wave
detectors to globe spanning networks of radio telescopes, we can
look forward to new discoveries and insights that will further
(25:18):
illuminate the nature of these most extreme objects in the universe.
The story of black holes is far from complete, and
each new chapter promises to be as fascinating as the last.
In the words of John Archibald Wheeler, who gave black
holes their name, black holes teach us that space can
(25:40):
be crumpled like a piece of paper into an infinitesimal dot,
that time can be extinguished like a blown out flame,
and that the laws of physics that we regard as
sacred as immutable, are anything but. In their darkness, black
holes illuminate the path toward a deeper understanding of the
US universe, a path that continues to unfold before us,
(26:04):
rich with mystery and wonder. Thanks for listening to this
episode of cosmic Curiosities. If you enjoyed this journey into
the heart of darkness, please subscribe for more explorations of
the universe's greatest mysteries. This has been Felix Mercer, brought
to you by Quiet Please Podcast Networks. For more content
(26:27):
like this, please go to Quiet Please dot ai. Until
next time, keep looking up. The Cosmos is calling.
Welcome to Cosmic Curiosities, where we journey through the most
fascinating phenomena in our universe. I'm your host, Felix Mercer,
and today we're diving into the mysterious realm of black holes,
those cosmic devourers that bend the very fabric of space
and time. This is episode forty two of our ongoing
(00:22):
exploration of the Universe's greatest puzzles, brought to you by
the Quiet Please Podcast Network. So dim the lights, settle in,
and let's fall into the unfathomable depths of these cosmic
enigmas together. Imagine, if you will, standing at the edge
of a cliff. But this isn't just any cliff. It's
(00:45):
a cliff in space, one where the rules we take
for granted start to unravel like a poorly knitted sweater.
The wind doesn't just blow here, it pulls, and below
you isn't solid ground, but a darkness so complete it
seems to swallow light itself. This, my curious friends, is
(01:06):
the neighborhood of a black hole, perhaps the most misunderstood
and fascinating object in our cosmic backyard. I've always found
it delightfully ironic that some of the brightest minds in
human history have dedicated their lives to studying these darkest
objects in the universe. Black Holes are cosmic contradictions. They're
(01:29):
simultaneously simple and complex, empty yet full, Theoretically sound yet
observationally elusive. They're the universe's ultimate magicians, making things disappear
without a trace, or so it seems. But today we're
going to peek behind the curtain of this cosmic magic show.
(01:52):
The story of black holes begins, as many good stories do,
with a thought experiment. Back in seventeen eighty, a fellow
named John Michelle, a geologist and astronomer with a particularly
vivid imagination, wondered what would happen if a star became
so dense that its escape velocity exceeded the speed of light.
(02:16):
He called these hypothetical objects dark stars. A few years later,
Pierre Simone la Place independently came to similar conclusions. Both
men were essentially describing what we now call black holes,
though neither had Einstein's theories of relativity to fully explain
the phenomenon. Fast forward to nineteen fifteen, when Albert Einstein
(02:40):
published his General Theory of Relativity, providing the mathematical framework
that would later be used to predict and describe black holes,
but Einstein himself was skeptical about their existence, believing them
to be mathematical curiosities rather than real astronomical objects. It
wasn't until nineteen sixty seven that astronomer John Wheeler coined
(03:03):
the term black hole, giving these cosmic phantoms the evocative
name we use today. Now, before we plunge headlong into
the depths of these cosmic devourers, let's establish what exactly
a black hole is in the simplest terms, though nothing
about black holes is truly simple. A black hole is
(03:25):
a region of space time where gravity is so intense
that nothing, not even light, can escape once it passes
a certain boundary. This boundary is what we call the
event horizon, which is a fancy way of saying the
point of no return. Imagine your canoeing down a river
that gradually becomes faster and more turbulent until it eventually
(03:47):
cascades over a waterfall. As you paddle along, there comes
a point where, no matter how hard you paddle in
the opposite direction, the current is too strong to overcome
that point. That critical threshold is analogous to the event
horizon of a black hole. Once you cross it, the
(04:08):
only way to go is down. The event horizon isn't
a physical surface you can touch or see. It's a
mathematical boundary, a point of no escape. If you were
unfortunate enough to cross this threshold, you wouldn't immediately notice
anything unusual. In fact, according to the laws of physics
(04:29):
as we understand them, you wouldn't feel any sudden jolt
or change as you cross the event horizon. This is
one of the many counterintuitive aspects of black holes. The
event horizon is less like a wall and more like
an invisible line of demarcation. But here's where things get
(04:49):
truly strange. From the perspective of someone watching you from
a safe distance, they would never actually see you cross
the event horizon. As you you approach it, the light
coming from you would be increasingly red shifted, stretched to
longer wavelengths by the intense gravitational field. Time itself would
(05:10):
appear to slow down from their perspective, and your image
would fade and freeze, creating what some physicists poetically call
a ghostly afterglow at the edge of the black hole.
This time dilation effect is a direct consequence of Einstein's relativity,
which tells us that gravity doesn't just pull on mass,
(05:31):
it pulls on the very fabric of space time. Near
a black hole, space time is so severely warped that
our intuitive understanding of time simply breaks down. If you
were wearing a watch as you fell into a black hole,
someone observing from afar would see your watch ticking more
and more slowly, eventually appearing to stop altogether as you
(05:54):
approach the event horizon. From your perspective, though, your watch
would tick along normally, and you'd cross the event horizon
without noticing this particular threshold. Of course, you would notice
other things, the gravitational tidal forces. The difference in gravitational
pull between different parts of your body would become increasingly
(06:16):
severe as you approach a black hole. For smaller black holes,
these tidal forces would become lethal long before you reach
the event horizon, stretching you vertically and compressing you horizontally
in a process delightfully termed spaghettification by physicists. I've always
(06:37):
thought that term adds a touch of culinary humor to
what would otherwise be a rather grim cosmic demise. For
supermassive black holes like the one lurking at the center
of our Milky Way galaxy, a monster named Sagittarius, aie
that weighs in at about four point three million times
(06:58):
the mass of our Sun. The tidal forces at the
event horizon would actually be much less severe. You might
survive crossing the event horizon at least momentarily before the
increasingly intense forces deeper inside would inevitably tear you apart.
It's a small comfort, I suppose, But when dealing with
(07:20):
black holes, we take our comforts where we can find them.
Once past the event horizon, all paths lead inexorably toward
the center of the black hole, toward what physicists call
the singularity. This is where our current physics breaks down
in a magnificent mathematical tantrum. According to general relativity, the
(07:41):
singularity is a point of infinite density and zero volume,
where spacetime curvature becomes infinite. It's a bit like dividing
by zero and mathematics you get a nonsensical answer that
suggests you've pushed your mathematical framework beyond its limits of applicability.
Many physicists suspect that the prediction of a true singularity
(08:05):
is a sign that general relativity is incomplete, not that
such infinities actually exist in nature. Quantum mechanics are other
great physical theory simply doesn't play nicely with general relativity
when it comes to describing what happens at the singularity.
This incompatibility has led to decades of research into quantum
(08:28):
gravity attempts to reconcile these two fundamental theories into a
more comprehensive understanding of the universe. Some approaches, like string
theory and loop quantum gravity, suggest that what we perceive
as a singularity might actually be something more complex and
less mathematically problematic. Perhaps the singularity is a densely packed
(08:52):
not of space time, or maybe it's a portal to
another universe entirely a cosmic escape hatch through a wormhole.
The honest truth is that we simply don't know, and
that's what makes this frontier of physics so exhilarating. We're
standing at the edge of human knowledge, peering into the abyss,
(09:12):
and the abyss is staring right back. While the event
horizon and singularity make up the basic anatomy of a
black hole, there's another feature that makes them visible to
us despite their light trapping nature. The accretion disc this
is the cosmic dinner plate from which a black hole
feeds a swirling maelstrom of gas, dust, and other matter
(09:37):
spiraling inexorably toward the event horizon. As matter in the
accretion disc orbits closer and closer to the black hole,
it speeds up and heats up due to friction and compression.
This superheated material can reach temperatures of millions of degrees,
causing it to emit radiation across the electromagnetic specectrum, from
(10:01):
radio waves to visible light to X rays. It's this
radiation that allows us to detect black holes indirectly, even
though the black holes themselves emit no light. The inner
edge of the accretion disk, just outside the event horizon,
is one of the most violent places in the universe. Here,
(10:22):
matter orbits at a significant fraction of the speed of light,
and the extreme conditions can cause jets of particles to
be ejected along the black hole's axis of rotation, sometimes
extending for thousands of light years. These jets are among
the most energetic phenomena in the universe, and they can
(10:43):
have profound effects on their surrounding environments, influencing the evolution
of entire galaxies. The accretion disc isn't just a feeder
mechanism for the black hole. It's also a cosmic laboratory
for testing physics under extreme can The inner regions of
these disks experience gravitational fields and velocities far beyond anything
(11:08):
we can replicate in terrestrial laboratories. By studying the radiation
from these regions, astronomers can test the predictions of general
relativity and other physical theories and environments where the effects
are pronounced and unmistakable. One particularly fascinating aspect of accretion
disks is their role in what we call active galactic nuclei.
(11:32):
These are the extraordinarily luminous central regions of some galaxies
powered by supermassive black holes actively consuming matter at prodigious rates.
The energy released in this process can outshine all the
stars in the host galaxy combined, making these active nuclei
visible across vast cosmic distances. Quasars, the most extreme examples
(11:58):
of active galactic nuclear are among the most distant and
energetic objects we can observe in the universe, with some
emitting the equivalent of trillions of suns now, not all
black holes are created equal. Based on their mass, astronomers
classify them into several categories, each with its own origin, story,
(12:22):
and cosmic significance. Stellar mass black holes, weighing in it
about five to several tens of solar masses are the
most common type. These form from the catastrophic collapse of
massive stars at the end of their lives. When a
star at least twenty times the mass of our Sun
(12:43):
exhausts its nuclear fuel, the outward pressure that had been
holding it up against gravity suddenly vanishes. The core collapses,
triggering a supernova explosion that blows off the outer layers
of the star. If the remaining core is massive enough,
generally more than about three solar masses, not even neutron
(13:04):
degeneracy pressure can halt the collapse, and a black hole
is born. These stellar mass black holes are the cosmic middleweights,
heavy enough to warp spacetime dramatically, but still relatively modest
on the cosmic scale. They are also the type that's
been most directly observed through their effects on companion stars
(13:26):
and binary systems. When a black hole orbits a normal star,
it can pull matter from the star, forming an accretion
disc that betrays the black hole's presence through its X
ray emissions. At the other end of the scale are
the supermassive black holes, the true heavyweights of the cosmic arena.
(13:48):
These behemoths can weigh millions or even billions of times
the mass of our Sun, and they reside at the
centers of most, if not all, large galaxies, including our
own Milky Way. The exact mechanism by which these gigantic
black holes form remains one of the great unsolved mysteries
(14:10):
in astronomy. One theory suggests that they grew from smaller
seed black holes, gradually accumulating mass by consuming gas, dust, stars,
and even other black holes over billions of years. Another
possibility is that they form directly from the collapse of
enormous clouds of gas during the early universe, bypassing the
(14:34):
stellar mass black hole stage entirely. Or perhaps it's a
combination of these processes, with the exact recipe varying from
galaxy to galaxy. What we do know is that supermassive
black holes have a profound influence on their host galaxies.
There's a remarkable correlation between the mass of a supermassive
(14:55):
black hole and various properties of its host galaxies bulge,
suggesting a coevolutionary relationship. The black hole, despite being tiny
compared to the galaxy as a whole, like a p
at the center of a sports stadium, somehow communicates with
and influences the development of the entire galaxy. This influence
(15:19):
likely occurs through the feedback effects of the black hole's
feeding process, as the energy released from the accretion disc
and jets can heat or even expel gas from the galaxy,
regulating star formation and galactic growth. Bridging the gap between
stellar mass and supermassive black holes are the intermediate mass
(15:41):
black holes, weighing in at hundreds to tens of thousands
of solar masses. These middleweight champions have been the most
elusive category, with evidence for their existence only recently becoming compelling.
Some ultra luminous X ray sources in nearby galaxies are
thought to be powered by intermediate mass black holes, and
(16:03):
there's evidence suggesting they might reside at the centers of
some globular clusters, dense conglomerations of ancient stars that orbit
galaxies like satellites. The origin of intermediate mass black holes
is still debated. They might form from the collisions and
mergers of multiple stellar mass black holes and dense star clusters,
(16:26):
or they could be the remnants of special types of
very massive stars that existed in the early universe. Some
might even be failed supermassive black holes seeds that began
growing but never reached the gigantic proportions of their more
successful counterparts. Understanding intermediate mass black holes is crucial for
(16:50):
filling in the evolutionary picture of black holes across cosmic time.
They could represent an important stepping stone in the growth
of supermassive black holes, and their study might help resolve
questions about how the cosmic heavyweights at the centers of
galaxies formed and evolved. A relatively recent addition to our
(17:11):
understanding of black holes came in twenty fifteen, when the
Laser Interferometer Gravitational Wave Observatory LIGO detected gravitational waves from
the merger of two black holes. This groundbreaking observation not
only confirmed a major prediction of Einstein's general relativity, but
(17:32):
also opened a new window for observing black holes. Through
gravitational waves, we can hear black holes colliding, providing information
that's complementary to what we learn from electromagnetic observations. The
LIGO detections have revealed a population of black holes in
the twenty to one hundred solar mass range, some of
(17:53):
which are heavier than what standard stellar evolution models had predicted.
This has led to new questions and theories about how
black holes form and evolve, including the possibility of hierarchical mergers,
where black holes that are themselves the products of previous
mergers combined to form increasingly massive objects. In twenty nineteen,
(18:17):
the event Horizon telescope collaboration gave us the first direct
image of a black hole's shadow, the dark silhouette cast
against the bright background of the accretion disc. This landmark
achievement focused on the supermassive black hole at the center
of the galaxy, and eighty seven provided a stunning visual
(18:38):
conformation of these extraordinary objects. The image shows a bright
ring of emission from the accretion disc, with a central
dark region corresponding to the shadow cast by the black hole,
a region about two point five times larger than the
event horizon itself due to the bending of light around
(19:00):
on the black hole. This image was followed in twenty
twenty two by a similar picture of Sagittarius, a star
the supermassive black hole at the center of our own
Milky Way galaxy. These images have not only captured the
public imagination, but have also provided valuable scientific data, allowing
(19:21):
astronomers to test the predictions of general relativity under the
most extreme conditions. Black Holes aren't just passive cosmic objects,
their dynamic entities that can change and evolve. When black
holes merge, they release an enormous amount of energy in
the form of gravitational waves ripples in the fabric of
(19:44):
space time that propagate outward at the speed of light.
The energy released in these mergers can be astounding. In
a typical black hole merger detected by LIGO, several solar
masses worth of energy are converted into gravitational radiation in
a fraction of a second, temporarily outshining the entire visible
(20:06):
universe and gravitational wave luminosity. Black Holes can also spin,
carrying angular momentum inherited from the matter that formed them
or fell into them. A spinning black hole drags the
fabric of space time around it in a process called
frame dragging, creating a region outside the event horizon called
(20:28):
the ergosphere. Within this region, it's impossible to remain stationary
with respect to distant stars. Space itself is rotating. This
spinning also affects the shape of the event horizon, causing
it to bulge outward at the equator, a phenomenon known
as the care geometry, named after mathematician Roy Kerr, who
(20:53):
found the solution to Einstein's equations for rotating black holes.
The spin of a black hole has profound implications for
its interactions with the surrounding environment, affecting the efficiency with
which it can convert matter into energy, and the structure
of the accretion disc and jets. Astronomers can measure black
(21:14):
hole spin by carefully analyzing the X ray emission from
the inner edge of the accretion disc, where the effects
of spin are most pronounced. One of the most mind
bending aspects of black hole physics involves what happens to
the information that falls into them. According to quantum mechanics,
(21:35):
information cannot be destroyed the complete data about the state
of a physical system must be preserved, even if transformed.
But black holes seem to destroy information, reducing everything that
falls into them to just three properties mass, charge and spin,
(21:55):
a principle known as the no hair theorem. This a
contradiction between quantum mechanics and general relativity has led to
the black hole information paradox, a problem that has vexed
physicists for decades. Stephen Hawking's discovery that black holes should
emit radiation due to quantum effects, now known as Hawking radiation,
(22:20):
only deepened the paradox. This radiation causes black holes to
slowly evaporate over mind bogglingly long time scales, but it
appears to be purely thermal, carrying no information about what
fell into the black hole. Various solutions to this paradox
have been proposed, from the idea that information is stored
(22:42):
in subtle correlations within the Hawking radiation to more exotic
possibilities like information being stored in a firewall at the
event horizon or in microscopic structures at the plankion level.
Some theories even suggest that information isn't true lost, but
is transferred to baby universes that butt off from our own,
(23:05):
or that it's stored in a holographic manner on the
event horizon. The resolution to this paradox will likely require
a full theory of quantum gravity, unifying our understanding of
the quantum world with Einstein's description of gravity. It remains
one of the most profound challenges in theoretical physics, sitting
(23:27):
at the intersection of general relativity, quantum mechanics, and thermodynamics.
Black holes also feature prominently in speculative but mathematically grounded
concepts like wormholes, hypothetical tunnels through spacetime that could potentially
connect distant regions of the universe or even different universes entirely.
(23:49):
While traversible wormholes remain firmly in the realm of theoretical
physics with significant obstacles to their practical realization, they highlight
the rich and strange possibilities that emerge when we push
our understanding of gravity to its limits. As we've journeyed
through the anatomy of black holes, from the event horizon
(24:11):
to the singularity, from the accretion disc to the various
types that populate our universe, I hope you've gained a
sense of why these objects captivate both scientists and the
public imagination. They are cosmic laboratories where the laws of
physics are pushed to their breaking points, revealing the cracks
in our understanding and pointing the way toward deeper truths.
(24:35):
Black holes remind us that the universe is not just
stranger than we imagine, but stranger than we can imagine.
They challenge our intuitions about space, time, and the nature
of reality itself. In their unfathomable depths lie some of
the most profound questions in physics, questions that may ultimately
(24:56):
lead us to a more complete understanding of the cosmos
and our place within it. As we continue to observe
these cosmic enigmas with increasingly sophisticated tools, from gravitational wave
detectors to globe spanning networks of radio telescopes, we can
look forward to new discoveries and insights that will further
(25:18):
illuminate the nature of these most extreme objects in the universe.
The story of black holes is far from complete, and
each new chapter promises to be as fascinating as the last.
In the words of John Archibald Wheeler, who gave black
holes their name, black holes teach us that space can
(25:40):
be crumpled like a piece of paper into an infinitesimal dot,
that time can be extinguished like a blown out flame,
and that the laws of physics that we regard as
sacred as immutable, are anything but. In their darkness, black
holes illuminate the path toward a deeper understanding of the
US universe, a path that continues to unfold before us,
(26:04):
rich with mystery and wonder. Thanks for listening to this
episode of cosmic Curiosities. If you enjoyed this journey into
the heart of darkness, please subscribe for more explorations of
the universe's greatest mysteries. This has been Felix Mercer, brought
to you by Quiet Please Podcast Networks. For more content
(26:27):
like this, please go to Quiet Please dot ai. Until
next time, keep looking up. The Cosmos is calling.
Popular Podcasts
Stuff You Should Know
If you've ever wanted to know about champagne, satanism, the Stonewall Uprising, chaos theory, LSD, El Nino, true crime and Rosa Parks, then look no further. Josh and Chuck have you covered.
Dateline NBC
Current and classic episodes, featuring compelling true-crime mysteries, powerful documentaries and in-depth investigations. Follow now to get the latest episodes of Dateline NBC completely free, or subscribe to Dateline Premium for ad-free listening and exclusive bonus content: DatelinePremium.com
New Heights with Jason & Travis Kelce
Football’s funniest family duo — Jason Kelce of the Philadelphia Eagles and Travis Kelce of the Kansas City Chiefs — team up to provide next-level access to life in the league as it unfolds. The two brothers and Super Bowl champions drop weekly insights about the weekly slate of games and share their INSIDE perspectives on trending NFL news and sports headlines. They also endlessly rag on each other as brothers do, chat the latest in pop culture and welcome some very popular and well-known friends to chat with them. Check out new episodes every Wednesday. Follow New Heights on the Wondery App, YouTube or wherever you get your podcasts. You can listen to new episodes early and ad-free, and get exclusive content on Wondery+. Join Wondery+ in the Wondery App, Apple Podcasts or Spotify. And join our new membership for a unique fan experience by going to the New Heights YouTube channel now!