[MUSIC PLAYING] This episode is supported
by the Great Courses Plus. One of the most enigmatic of
all astrophysical phenomena is the mighty quasar. They're also a subject
of my own research, and so are close to my heart. Let's talk about what happens
when the largest black holes in the universe start to feed. [MUSIC PLAYING] Space stuff is awesome. Take stars-- 100 billion
megaton per second thermonuclear explosions that just
don't stop exploding. Pulsars-- city-size
atoms that beam deathrays through the galaxy. Giant molecular clouds--
beautiful and tranquil, but also screaming vortices
spitting stars into the cosmos. Of course, everyone knows that
quasars are the most awesome of all. They have everything. They're like the fire-breathing
bat-winged vampire rainbow zebra unicorns of
astrophysical phenomena. They don't just
have a black hole. They have a
supermassive black hole, millions to billions of
times the mass of the sun. That's surrounded by a
solar system-sized whirlpool of superheated
plasma that shines brighter than an entire galaxy. Sometimes they even have
jets of near light speed particles filling the
surrounding universe with giant radio plumes. Yep, quasars are
clearly the most metal of all the space things. This is one reason why
I study them myself. But it's not just
that they're cool. Quasars helped
shape our universe. In fact, without
these most violent of all astrophysical
phenomena, we might not be here
to think about them. Let me start with
a bit of history. When the very first
radio telescopes pointed to the heavens,
they saw fat blobs of radio light, whose
sources were unknown. Those blobs were only blobby
because those early radio antennae had some pretty
bad spatial resolution, making it difficult to pinpoint
exactly where on the sky they were located. Then, in 1962, astronomers
caught a break. In an event known
as an occultation, the moon passed right in
front of one of the brightest of these radio blobs. It was object number 273 in the
brand new 3rd Cambridge Radio Catalog-- 3C273, for short. The Parkes radio
telescope in Australia was trained on the
occultation and registered the exact instant
that the radio signal vanished behind the moon. That timing allowed
astronomers to identify a tiny star-like
point of bluish light as the source of
the radio emission. Astronomers turned
their optical telescopes on this strange star, and split
the light into a spectrum. It looked nothing like the
spectrum of any star ever seen. And so the name quasi stellar
radio source was born. Later, to become quasar. But what was so different? For one thing, its
spectrum was redshifted, the wavelength of its
light stretched out as those photons traveled
through the expanding universe. That put 3C273 very far away. Its light must have been
traveling from two billion light years away to acquire
the observed redshift. Yet, to be as bright as it
appeared at that distance, the weird object
had to be emitting many galaxies worth of light
from a seemingly impossibly small region of space. A hysterical flurry of
hypothesizing followed-- swarms of neutron stars,
an alien civilization harnessing their
entire galaxy's power, bright, fast-moving
objects being ejected by our own galaxy's core. But by the 1980s, we were
converging on the most awesome explanation. It goes a little like this. Take a black hole of millions
to billions of times the mass of the sun. Where from? Well, it turns out
that every decent sized galaxy has one at its core. Now, drive gas into
the galactic core. One way this can happen is
when galaxies merge and grow. That gas descends
into the waiting black hole's gravitational
well and gains incredible speed on the way. It is swept up into a raging
whirlpool around the black hole that we call an accretion disk,
where its energy of motion is turned into heat. The heat glow of
the accretion disk is so bright that
we can see quasars to the ends of the universe. Some gas is swallowed, causing
the black hole to grow. However, a lot of it never makes
it below the event horizon. Some is converted directly into
energy and radiated as light. And this same light drives
powerful winds of gas back out into the surrounding galaxy. In some cases, for reasons
we don't fully understand, some of that gas can also
be swept up and collimated, channeled into jets that erupt
from the poles of the quasar. This may be due to
the magnetic field of a rapidly
rotating black hole, but the jury is still out. The exact appearance
of this phenomenon depends enormously
on our viewing angle. Looking down onto a
bright accretion disk, we see a quasar in
all of its glory. But viewed side on,
that disk is obscured by a thick ring of dusty gas. Then, we only see hints
of the central monster because it lights up gas
in the surrounding galaxy. However, if such an edge-on
quasar has powerful jets, we see them blasting
through the galaxy and even filling intergalactic
space with beautiful radio plumes. We call these radio galaxies. Oh, and if one of these jets
happens to be pointed directly at us, then we see
strange effects due to the near light speed
motion of the jet material. In an effect called relativistic
beaming, the light from the jet is vastly magnified. These rare cases
are called blazars. So when a supermassive black
hole feeds and blasts energy into the universe, what we see
depends on its orientation, whether or not it has a jet,
the power of the accretion disk, and a few other
properties besides. However, the family
name for any type of accreting
supermassive black hole is active galactic nucleus. This is a simplified description
of our modern understanding of quasars and active
galactic nuclei. But it was a hard
won understanding. Most of the energetic
craziness happens on a size scale similar to our
solar system, or even smaller. We're talking, at most,
a few light days across. But when viewed from halfway
across the observable universe, that is impossibly tiny. Even for 3C273, the
nearest bright quasar, the accretion disk falls into
a region less than 100,000 times smaller than a single
pixel on the Hubble Space Telescope. Over half a century
after their discovery, we're still hard at
work on this puzzle, and not just for the fun of it. Anything as
energetic as a quasar must have had an
influence on the universe. The first quasars turned
on in a very young universe that was still thick
with the raw hydrogen gas produced in the Big Bang. As the first galaxies
coalesced from this gas, the universe entered
a long period of violent star formation. As galaxies coalesced, they
went through starburst phases, producing new stars
at insane rates. The birth of large
numbers of new stars is always quickly followed
by the explosive deaths of the most massive, shortest
lived of those stars. Waves of star
formation, followed by waves of supernovae. These forming galaxies
were continuously blasted with energetic radiation
and cosmic rays. If life did manage to evolve
during this earlier epoch, it would have been
quickly obliterated. However, the same
rich gas supplies that fueled those
starbursts also gave rise to the
epoch of quasars. As some of this
gas found its way into the nuclei of
galaxies, it encountered there the supermassive
black holes that had been growing since
the beginning of the universe. Accretion disks formed, and
many knew quasars were born. Each burst of quasar
activity in a given galaxy probably only lasts 10
million years or so. However, that's enough to heat
gas throughout the galaxy. Hot gas doesn't
collapse into stars, and so the extreme starburst
activity was shut down. A few billion years
after the Big Bang, when the universe was around
a quarter of its current age, both starbursts and
quasars started to dwindle. Galaxies had formed, but were
no longer wracked by supernovae. Life finally had a chance. We are now well out
of the quasar epoch. Active galactic nuclei still do
fire up in the modern universe, although usually they
are at full quasar power. The much weaker, Seyfert
galaxies are more common. But good old 3C273 is
a full blown quasar. In fact, it's one of
the most luminous known. Although it's far
away, its light comes to us from a time long
after the peak of the quasar epoch. It's a late relic from
a more violent time. But it's not the last. Perhaps in a few
billion years, when the Andromeda galaxy
and the Milky Way inevitably collide and their
supermassive black holes merge, the violence will deliver
one last wave of fuel to the combined galactic
core, and a new quasar will shine forth, illuminating
this little patch of spacetime. Thanks to the Great Courses Plus
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lus.com/spacetime. Hey, guys, I want
to give a big thank you to all our
Patreon supporters, and to all our about to
be Patreon supporters. Links to follow. And a very, very big thank
you to Tambe Barsbay, who's supporting us
at the quasar level. Tambe, your own personal
spacetime quasar is in the mail. Expect it in two to
four billion years. [MUSIC PLAYING]
Hey Space-Time. I saw this question in another reddit thread, and I think you ( or the community here ) would be up for a good answer to it: If an object that is both more massive than a black hole and larger than the swartshield radius for it to collapse into a black hole were to itself enter a less massive existing black hole, what would happen? How would the matter connecting the massive object react to the smaller mass hole? What if the object were made from a material-matter composition that is the strongest lattice of matter that could be formed ( graphine-super matter )?
I'm guessing the same thing would happen to the mass no matter it's composition; matter would still be connected but be warped by the infinite warping of space that the smaller black hole is creating in it's area. Though I would be interested to find out if black holes are strong enough to rip any material at the atomic level away from its already formed bonds, no matter how strong those bonds are.
I hope this makes it into Space Time. I love your stuff!
Edit: to clarify my question a bit after realizing something. If the size of the solid object falling in is larger than the event horizon of a black hole*. I realized you can answer this by saying the singularity, as far as we understand is the size of the Planck length, so every object falling in it is technically bigger.