- 4/15/2025
Black holes are not the violent monsters people think they are, and new discoveries reveal that they might have been essential to creating stars, giving light, and building the universe itself.
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LearningTranscript
00:00Black holes, long considered the bullies of the cosmos.
00:07But are they really so bad?
00:11Black holes aren't violent, they are elegant.
00:15They're incredibly powerful objects, but they're beautifully simple.
00:20Simple, but unpredictable.
00:23Black holes rip planets to shreds, but they also give birth to stars.
00:29Black holes are like the ultimate recycling trash bin combination.
00:36They build galaxies and may have lit up the dark infant universe.
00:44It's one of the biggest changes that happened.
00:48Someone switch the lights on and transforms our universe.
00:53They come in all sizes, from microscopic to ultramassive.
00:58Controlling the fate of everything around them.
01:02The story of the universe and how it's arranged is the story of black holes.
01:07Black holes are the master architects of the universe.
01:11And without them, we would not exist.
01:14Black holes. We're riveted by their destructive power.
01:18Black holes. We're riveted by their destructive power.
01:27Black holes are dangerous. Black holes are hazards. Black holes are not friendly for humans.
01:33There's just no good ends to anything that falls into a black hole.
01:40Perhaps one of the most frightening objects in the universe.
01:47But what exactly are these scary objects?
01:49Black holes are created when you get enough matter in a small region of space.
01:53This happens when a massive star dies and collapses in on itself.
02:00A supernova.
02:01A supernova.
02:03A black hole is the ultimate consequence of gravity.
02:05It's an object that has so much mass crushed into such a small space that its escape velocity becomes greater than the speed of light.
02:10It's an object that has so much mass Yeah.
02:11This happens when a massive star dies and collapses in on itself.
02:15A supernova.
02:21A black hole is the ultimate consequence of gravity.
02:27It's an object that has so much mass crushed into such a small space that its escape velocity becomes greater than the speed of light.
02:38They are a one-way street.
02:42You go in, nothing escapes not even light.
02:47But do black holes really deserve their bad rap?
02:53In some ways, I think we set up black holes to be more villains than they actually are.
02:58Black holes suffer a bit of a PR problem.
03:01I think they're a lot more menacing in science fiction and popular media than they really are.
03:07There are trillions of galaxies in the known universe.
03:18And most of them have a supermassive black hole at their center.
03:27These monsters are millions of times the mass of our sun.
03:32Their immense gravity can send stars flying.
03:36They're instrumental in choreographing the dance of stars in their vicinity.
03:43Supermassive black holes shoot out torrents of lethal radiation and violent cosmic winds.
03:50And gobble up anything that comes close.
03:55Now scientists are beginning to realize these cosmic giants may also have a creative side.
04:05Most people think of black holes as being like giant vacuum cleaners in space and basically everything falls into them.
04:10But that's not actually the case.
04:13They're better thought of as the engines of cosmic change.
04:18Although black holes are the end states of stars, they can actually influence the formation of stars as well in a bunch of different ways.
04:28A galaxy's job is to make stars.
04:33But uncontrolled star growth isn't healthy.
04:37Too many stars can drain a galaxy's gas supply.
04:41Black holes are very important.
04:44It appears that galaxy evolution is tied to black hole evolution.
04:50We don't know exactly how yet, but the marriage appears certain.
04:57One idea is that supermassive black holes act as cosmic control mechanisms.
05:05Black holes can act like a thermostat in your house.
05:09If your house gets too hot, the thermostat will kick on the air conditioner.
05:13And if it gets too cold, it'll kick on the heater.
05:16Black holes do the same things for galaxies.
05:20Supermassive black holes regulate star formation by pulling gas in and shooting it back out into the galaxy.
05:30When these black holes are consuming matter, they're drawing matter into themselves,
05:34but they're also spewing stuff out.
05:37Basically, black holes eat like little babies, very sloppily.
05:42So a lot of what they eat comes flying back out again.
05:46They eat stars, they eat planets, but most often they eat giant clouds of gas.
05:52The black hole drags gas and dust into an accretion disk around it.
05:57This disk spins faster and faster.
06:01Magnetic energy builds up.
06:03With the accretion just swirling around the black hole, there are also magnetic fields that are going on.
06:10The material is moving so rapidly that the magnetic field sort of winds up, coils up, and forms a vortex like a tornado.
06:17Astronomers call them jets.
06:22These jets propagate outward like freight trains plowing through the galaxy over hundreds and thousands of light years.
06:33These are like death rays.
06:37The jets disrupt the star-forming gas clouds, limiting excess star formation in the main body of the galaxy.
06:44But in the very outer reaches of the galaxy, they can spark star birth.
06:51Things are more gentle out there. You're not as close to the energetic heart.
06:55So stars, planets, and life can form out there partially because of the material that the black hole has moved out there.
07:02So black holes can have outsized influence on the regions that they inhabit.
07:09Right around them, they can prevent the formation of stars.
07:14Whereas on very, very large scales, they can actually instigate the formation of stars.
07:212018, black holes hit the front page.
07:36Scientists discovered black holes gobbling up gas so fast that they seem to be outgrowing their host galaxies.
07:44It naturally makes the question come up, how big can a black hole get?
07:50Now, we have the answer.
07:52They can reach size XXXL, becoming ultramassive black holes.
08:15Ultramassive black holes are so cool because it's just mind-boggling that black holes so large can exist.
08:22Ultramassive black holes are very rare and typically have masses of more than 10 billion times the mass of the sun.
08:30Ten billion solar masses. That's a ten followed by nine zeros.
08:37Ultramassive black holes are real beasts.
08:40The black hole at the center of our galaxy is four million solar masses.
08:44Imagine black holes that are 2,500 times bigger. That's what we're talking about here.
08:50An ultramassive black hole this big would be as wide as the solar system and weigh as much as all the stars in the Milky Way.
09:05There are inside galaxies that aren't a whole lot bigger. That really surprised the hell out of everybody.
09:16And in 2018, scientists discover a 20 billion solar mass ultramassive black hole growing faster than any other black hole.
09:30This ravenous behemoth devours the mass of our sun every two days.
09:39These big black holes are really good at gobbling up other things.
09:43They literally eat anything. They're monsters of the universe.
09:48This kind of voracious eating can have devastating consequences.
09:53It blasts so much energy and turbulence into the galaxy that stars no longer form.
10:02And the bigger the black hole, the faster the galaxy dies.
10:07The primary thing these ultramassive black holes do to galaxies is they shut down all star formation.
10:12And so in that sense, they kind of kill galaxies.
10:15And so these things could even wipe out their host galaxies.
10:20Ultramassive black holes are a problem for scientists too.
10:25They might be the fastest eaters.
10:29But that doesn't explain how they got so large.
10:34With these ultramassive black holes, these black holes that are tens of billions of times more massive than our sun,
10:41you can't just grow them from the slow accretion of gas over time.
10:45There's just not enough gas and there's just not enough time.
10:50It gives us a new mystery to solve.
10:52How do you make black holes that are just that big?
10:54There's not a clear answer so far as to how these ultramassive black holes were formed.
11:00People wonder if there is some other mechanism by which you could make black holes.
11:05A mechanism so violent, it also throws supermassive black holes clean out of galaxies.
11:12We now know that ultramassive black holes, billions of times the mass of the sun, exist.
11:31But we have no idea how they got so big.
11:35We've detected lightweight stellar mass black holes colliding.
11:40They merged into a new larger black hole and generated huge amounts of energy.
11:52But what about supermassive black holes?
11:55When galaxies merge, their central supermassive black holes will fall to the center of the newly formed galaxy.
12:02Could these supermassive black holes, caught up in galactic mergers, combine to form an ultramassive black hole?
12:21In 2017, the Hubble Space Telescope spotted something strange in a distant galaxy called 3C 186.
12:32It detected an incredibly bright spot, thousands of light-years from the galaxy's center.
12:39Scientists suspect it's a quasar.
12:43A quasar is an incredibly bright, active galactic nucleus that's powered by a supermassive black hole.
12:51We regularly spot black hole-powered quasars, but always at the centers of galaxies.
13:01Until now.
13:02When we actually got this data from Hubble, we were absolutely stunned to discover that the quasar that we've long known to exist in the center of this galaxy wasn't actually at the center.
13:14This black hole is offset from the center of the galaxy by about 35,000 light-years. That's really weird.
13:21It is an incredibly rare and bizarre event to find a quasar, a supermassive black hole, that is not at the center of the galaxy.
13:30When scientists looked closer, they discovered that the quasar is hurtling through space, away from the center of the galaxy.
13:39Now mind you, this is a black hole with the mass of about a billion times the sun, and it's screaming away at four million miles an hour.
13:48This black hole, which was probably originally in the galaxy's center, has somehow been shot out at high velocity by some incredibly violent event.
13:58It's hard to imagine what kind of event would pump that much energy into such a huge object to shoot it away from the center of a galaxy.
14:08Who kicked it out, how, and why?
14:12Scientists have an idea.
14:153C186 may be the remnant of a galaxy merger.
14:18The merged galaxies, supermassive black holes, circle each other, sending out blasts of energy in the form of gravitational waves.
14:33Gravitational waves are all around us. They're ripples in the fabric of space-time.
14:40Every time mass moves, gravitational waves are produced.
14:44So if I wave my hand, I am making gravitational waves.
14:49A hand produces imperceptible waves.
14:54When objects as huge as supermassive black holes collide,
14:59the energy released as gravitational waves is phenomenal.
15:06Scientists think these black holes might have been different sizes.
15:10It's possible that if one of the black holes is really massive and the other one isn't quite as massive,
15:17that when they spiral around and merge, they send out gravitational waves in an asymmetric way.
15:22This asymmetry has a catastrophic effect.
15:33As the two black holes collide and merge, they shoot out a huge blast of gravitational waves, but only in one direction.
15:43This blast of energy kicks the newly combined black hole out of the galactic center.
15:53Think of a shotgun recoil, but supersized.
15:57There's so much energy in that emission that it acts like a rocket and it actually pushes the merged black hole away.
16:02It would have been one of the most energetic events ever witnessed.
16:10They're so energetic, they are literally shaking the fabric of space.
16:15We didn't witness the actual collision, but 3C-186 could be evidence that supermassive black holes can collide and merge, building even larger black holes.
16:33This would be a mechanism by which you would create ultimately an ultramassive black hole.
16:41As for the ejected black hole, the gravitational recoil sent it on a one-way ride to oblivion.
16:50So gravitational waves kicked this supermassive black hole and sent it flying through space.
16:57In 20 million years, it's expected to exit its galaxy.
17:00The ejected supermassive black hole may eventually hit another galaxy and merge with its supermassive black hole.
17:16These largest of black holes seem to throw their weight around, bullying galaxies and other black holes.
17:23Now, researchers have discovered a vampire black hole that's draining the lifeblood of its neighbor.
17:33超巳 in orbit
17:40While supermassive black holes seem to regulate star formation.
17:52to destroy their galaxies while supermassive black holes seem to regulate star formation
18:00but are all supermassive black holes forces for good
18:10hundreds of galaxies surround the milky way large and small but most of the largest galaxies are red
18:22this is not a good omen in space red means danger
18:30if you have active ongoing star birth then you have massive stars and massive
18:34stars tend to be blue but they don't live very long and they blow up
18:42once you stop star formation after some amount of time the galaxy turns red
18:46the only stars left alive are small long-lived red stars called red dwarves
18:56a red galaxy with only red dwarves is a dying galaxy
19:02the sloan digital sky survey found an entire population
19:06of these luminous red galaxies that were no longer forming stars that were dead
19:16one galaxy around 340 million light years away stood out
19:24it was named after a japanese anime character akira
19:29it's very red all the stars in it are red and that means they're old
19:33so we know that akira has not had any active star formation in a long time
19:40the akira galaxy doesn't form stars because it doesn't have the cool calm gas needed to build them
19:48something is heating the gas making it turbulent
19:54one of the ways in which a black hole can drive the evolution of the galaxy in which it resides
19:58is by simply powering a wind these are winds that are literally driven by light
20:08when a black hole feeds it drags gas into an accretion disc
20:14the disc heats up and gives off light radiation
20:20the radiation pressure from the accretion disc around this black hole
20:24couples to the ambient gas and dust and pushes it outwards at very high velocity
20:31these wings that are driven out by the black hole essentially warm up the gas
20:37in the galaxy preventing further star formation
20:43however whatever's fueling the black hole in akira is a mystery
20:47here's a weird thing there is an outflow a wind coming out of this galaxy and that means there's gas
20:55feeding that black hole in the center and it's blowing it out where's this gas coming from
21:02ah it's stealing it it has a small companion galaxy which is nicknamed tetsuo and that has gas in it
21:10akira's super massive black hole pulls gas from tetsuo and drags it into the center of the galaxy
21:23the black hole is taking the gas from this companion galaxy and that's what's falling
21:28around the black hole and creating this wind so akira is actually sort of a dead galaxy but
21:33it's being rejuvenated by its companion tetsuo
21:40like a cosmic vampire akira's supermassive black hole feeds off tetsuo
21:49the black hole drags gas and dust into its accretion disk which spins faster and faster
21:57and these particles are rubbing against each other well that generates friction
22:01friction may not seem like that big of a deal i mean you can rub your hands together on a cold day
22:06to get warm but imagine rubbing your hands together at very nearly the speed of light
22:11how much friction is that going to generate it's going to make a lot of heat
22:16over a million degrees fahrenheit
22:20so hot the accretion disk lights up
22:23it's temperature goes up and he starts emitting light it becomes incredibly bright
22:33even though there's a black hole in the core its surroundings are intensely bright
22:41this heats up the surrounding gas generating a hot wind which extends thousands of light years from the
22:48black hole and those winds carry with them a lot of energy and that energy if it couples to the gas in
22:56the galaxy can blow that gas out they inject energy into nearby gas clouds and heat them up and prevent them
23:03from forming stars stars don't form the galaxy dies
23:09these dying galaxies are called red geysers
23:19scientists think around 10 percent of the red galaxies we see around us died this way
23:28heated up by this galactic warming
23:34we think that the source of some of this galactic warming
23:37is in the growth of supermassive black holes themselves because when you grow a supermassive
23:41black hole you must liberate an enormous amount of energy you can't grow a black hole for free
23:48and that energy gets dumped back into the ambient surroundings
23:52and keeps this halo of gas hot it prevents it from cooling and forming stars
24:00sagittarius a star the supermassive black hole at the heart of our galaxy
24:06the milky way could turn into a red geyser
24:10if you were suddenly to dump an enormous amount of gas onto sagittarius a star
24:15you could have what is effectively a red geyser effect a very powerful wind driven by all of this energy
24:21star formation would stop and our milky way would become another dying red galaxy
24:38now new research suggests that sagittarius a star has already affected the inner region of our galaxy
24:47not by killing stars but by transforming planets from gas giants into super earths
25:05a supermassive black hole at the center of our galaxy lies a supermassive black hole sagittarius a star
25:19we think it's calm dormant safe relative to other supermassive black holes in the universe ours is
25:27relatively quiet it's been active in the past and it could flare up in the future it could be active
25:36tomorrow for all we know all you need to do to light it up is start dumping some gas on it
25:41and there is almost certainly a giant cloud of gas that we don't currently know of on its way to the
25:46center of our galaxy and it will find itself one day in the vicinity of our supermassive black hole
25:51and it will start to light up like a christmas tree in february of 2018 scientists at harvard
26:00simulated sagittarius a star during a feeding frenzy to understand the impacts of an active supermassive
26:08black hole on its local environment
26:14they found that as sagittarius a star gobbled up gas and dust
26:18it belched out bright flares of high energy radiation
26:24which radically affected the region around the black hole
26:29the environment near the center of a galaxy that has an actively feeding black hole
26:34is the worst place in the universe you've got this tremendous object which is heating up this gas to
26:41millions of degrees this is no place that you want to be
26:45the model revealed what would happen to any planets in the line of fire
26:54think about being in the way of one of these black hole burps
26:57all of a sudden there's a tremendous wind radiation that comes through your solar system
27:02that could actually strip away the outer layers of gas of a planet like neptune
27:06the high energy radiation from the supermassive black holes would hit the gas planets and heat up their
27:15atmospheres maybe this would actually strip away the outer layers leaving the solid material in the
27:21middle you could actually turn a gas giant planet into a terrestrial solid planet all because you're
27:26close to a black hole this radiation strips away the gas leaving the core now a new rocky planet
27:38but a giant one a super earth normally you think of rocky planets being about the size of the earth
27:45but this would be a way of making so-called super earths
27:48super earths are one of the most common type of planets discovered in our galaxy
27:55it's possible that any super earths close to sagittarius a star were created by these blasts of energy
28:07away from our galactic center a much smaller stellar mass black hole is also radically transforming its
28:16environment
28:20january 2017 researchers discover something strange in a cloud of gas called w44
28:30w44 is a supernova remnant it's the debris the expanding cloud from a star that blew up
28:37the explosive shockwave from a supernova
28:39it pushes gas and dust out from the dead star forming a huge nebula
28:49we see a lot of these i mean they're catastrophic amazing incredible events but as far as they go this
28:54one appears to be pretty standard except for one weird thing in the heart of it there's something very
29:01mysterious going on there seems to be something shooting out of the very center of this explosion
29:09a thin protrusion trillions of miles long streams out from the cloud
29:20it's moving at over 60 miles a second against the flow of the galaxy
29:26it's very strange that it's moving backwards against the rotation of the milky way
29:30when you see a giant giant very massive cloud of gas that is moving counter to the rotation of the
29:37milky way it needed to be like a bullet from a gun fired it against a headwind in the opposite
29:42direction so what is that gun you know what fired that bullet of gas
29:46the tip of the bullet cloud is expanding at 75 miles a second that's 270 000 miles an hour over 150 times
29:58faster than a bullet what's in the cosmos has the power to accelerate gas to such high speed
30:07could that actually be a black hole moving very very quickly
30:10researchers think a stellar mass black hole hidden in the bullet cloud is powering the movement of
30:18the gas gravity from this black hole is incredibly strong and so it will latch onto this gas cloud as
30:24it passes through it and it can completely disrupt the motions of this cloud this is a very interesting
30:30stream of gas that's somehow connected to a black hole and we don't know whether it's there because
30:35the black hole is moving through the gas and it's creating a wake or whether somehow uh this black
30:40hole is spitting out a stream of material in some way the black hole could be dragging gas into an
30:48accretion disk around it the gas heats up and expands giving the initial supernova explosion w44 an extra kick
30:57driving this bullet like cloud out in front of it or the black hole could be racing away from the nebula
31:07dragging the gas behind it like a wake
31:17ultra massive super massive and stellar mass black holes all play a role in shaping the cosmos
31:24the cosmos but there may be another type of black hole even more dangerous than the rest
31:32a microscopic black hole
31:54we have so far detected triple xl ultra massive black holes large super massive black holes medium
32:03sized intermediate black holes and small stellar mass black holes now scientists have another to add to
32:13the roster microscopic black holes we know there are super massive black holes at the centers of galaxies
32:21we know there are star sized black holes from the depths of stars that's what we know for sure
32:26it's possible there are much smaller black holes microscopically small black holes
32:32microscopic black holes are virtually invisible to the naked eye but magnified they look like regular
32:40stellar mass black holes
32:41the definition of a black hole is an object that has so much mass crushed into such a small space
32:50that its escape velocity becomes greater than the speed of light so it could be something the size of
32:54a star the size of a galaxy it could also be the mass of a planet if you could crush the earth down far
33:02enough it could become a black hole the density of a black hole is something that the human brain really
33:08doesn't wrap itself around very easily when you think about something the size of the earth
33:13how small would the earth have to be to be a black hole and the answer is something on the order of a
33:17marble so think about taking the entire earth and compressing it down to the size of just a marble
33:25so where did these strange little black holes come from
33:30these very small black holes can only be formed in the exotic conditions
33:35of the incredibly early universe our universe might get flooded with these small black holes that
33:42simply persist to the present day it's the only time in the history of the universe where you
33:49could take a small amount of matter and crush it down so tightly that it could become a black hole
33:54those conditions don't exist anymore so if these things exist they would be primordial they would be as
34:00old as the universe itself these primordial black holes may be ancient but they still pack a punch
34:16black holes size doesn't matter for a black hole what matters is mass mass determines its gravitational
34:25attraction its gravitational effects on its environments and when it comes to black holes the
34:32smaller black holes are actually more dangerous because their mass is concentrated into such a small volume
34:40you can have differences strong differences in gravity between different distances from that black hole
34:48if paul or an interstellar robotic probe visited a supermassive black hole or even an ultra massive black hole they wouldn't be immediately ripped to shreds
35:03one of the most fun questions about black holes is how close could you get to a black hole before the gravity would rip you apart
35:09and that actually depends on the volume of the black hole if the black hole is very large you could get very very close
35:16the more massive they are the slightly softer they are and how they tear things apart
35:22so a supermassive black hole actually you can cross within the event horizon and not really notice it
35:28you're never going to get back out but you won't necessarily be stretched to your death while you cross inside
35:37so a probe could visit a supermassive black hole and not be destroyed
35:41until it crossed the event horizon and traveled deep inside
35:51then it would be torn to pieces
35:56but microscopic black holes are currently just a theory microscopic black holes have been the focus
36:05for some researchers for many years but currently there's no evidence to support their existence
36:11microscopic primordial black holes may or may not have been around since the big bang
36:22now scientists have discovered supermassive black holes from the very early universe
36:29they're shedding light on one of the most mysterious eras the cosmic dark ages
36:41black holes don't just shape the universe now they've been shaping it from almost the dawn of time
36:59scientists think black holes may have triggered one of the universe's greatest transformations turning
37:05from dark and foggy to transparent and light
37:17at the beginning of time the universe was a tiny ball of super hot energy the big bang
37:26shortly after a big bang our universe was shining bright because it was full of hot glowing gas
37:34then it cooled off and entered the so-called dark ages until eventually something lit it up again
37:42one of the biggest changes that happened in our universe someone switched lights on and transformed the universe
37:50during the dark ages the universe was blanketed in a thick fog then something lit it up in a process
37:58called re-ionization we still don't really know for sure whether re-ionization was mainly caused by
38:07young stars or whether it was mainly black holes that ate stuff and spewed out a bunch of radiation
38:14then in december of 2017 researchers in chile scan a region of space so far away
38:26it takes light 13 billion years to reach us they spot an object from just 690 million years after the big bang
38:37when the universe was only five percent of its current age it's called quasar j1342 plus 0928
38:52the thing that's so amazing about this farthest quasar is we may actually have seen the boundary of these
38:57dark ages this particular supermassive black hole slash quasar tells us something about the formation of
39:06the early universe it's thought that quasars helped drag the universe out of the dark ages they gobbled
39:13up so much hydrogen gas and belched out jets of energy and cleared up the fog those jets could have
39:23actually put so much energy into the universe that it made it clear again we may actually be seeing the
39:29moment where something punches through this boundary of the dark ages
39:38pockets of re-ionization opened up throughout the early universe
39:43they came in different sizes depending on what created them
39:50while our universe was being re-ionized it was kind of like all these holes that kept growing
39:55if the re-ionization was made by a large number of little stars you would have many many small holes
40:02much like a sponge
40:05whereas if you uh had a small number of monster black holes doing it you'd have a lot of big holes
40:13like dennis swiss cheese
40:14at present we can't measure the ionized pockets to determine if it was stars or black holes that lit up
40:26the early universe perhaps it was both black holes and stars working together
40:34the more we investigate black holes the more we learn about their role as architects of the universe
40:56i think scientists of my generation are very lucky to be able to be at the beginning of this revolution
41:04we used to portray black holes as monsters now we know that without them the universe would be a
41:11very different place they made life possible without black holes we probably wouldn't exist
41:18we're discovering just how black holes shaped the universe but the more we learn the more questions
41:26they pose i've spent my career studying black holes and i want to spend the rest of my career studying
41:33black holes and i guarantee you that at the end of my career on the day i retire i will probably have
41:41more questions about black holes than i do today this is an incredibly exciting time for black hole science
41:50who knows what we're going to discover
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