What Happens When Two Black Holes Collide?! | How the Universe Works | Science Channel

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0:00We're taking our seats for the most

0:02violent event in the universe, the

0:05collision of two super massive black

0:08holes. We've never witnessed this cosmic

0:11heavyweight championship, but we can

0:13build up a picture of this epic fight by

0:15studying other weight classes with

0:17lighter fighters.

0:232020, the Earthbound Gravitational Wave

0:27Detector, LIGO, picks up the distinctive

0:30signal of a stellar mass black hole

0:32merger.

0:34What we saw was a black hole of 85 times

0:38the mass of our sun and another black

0:40hole of 66 times the mass of our sun

0:43smashing together to create a combined

0:46black hole.

0:48As someone who studies black hole

0:50mergers, this was a really exciting

0:52event.

0:53>> We're talking about the largest, the

0:55heaviest, the most massive black holes

0:57we have seen collide to date.

1:01It may be the largest detection, but on

1:04a universal scale, it's still a small

1:06fry. Like lightweight boxers, the two

1:09black holes circle each other and emit

1:12low energy gravitational waves.

1:16This energy loss causes the black holes

1:18to spiral in together.

1:21Finally, they collide in a cosmos

1:23shattering event,

1:26forming a single black hole and

1:29releasing a huge blast of gravitational

1:32waves. But when astronomers examine the

1:36single merged black hole, something

1:38doesn't add up.

1:40>> If you take the combined mass of the two

1:42black holes, you get to 150 times the

1:46mass of our sun. But actually, the black

1:48hole that's left only has a mass of 142

1:53times the mass of our sun. So, the mass

1:56you have before the event does not equal

1:59the mass you have after the event. What

2:02happened to that missing eight solar

2:05masses? The way these black hole mergers

2:07work is very roughly 5% of the total

2:10mass of the system gets converted into

2:13energy.

2:15It all comes down to E= MC^2.

2:20>> This is that beautiful equation that

2:22Einstein told us. E= MC². E is the

2:25energy and M is the mass.

2:28>> Einstein taught us that mass and energy

2:30are related. In fact, much of what we

2:33call mass is actually energy. In this

2:36case, the violence of the collision

2:38transforms 18,000

2:41trillion trillion tons of matter into an

2:44explosion of gravitational waves.

2:48>> In just a fraction of a second, 8 suns

2:52worth of matter is converted into pure

2:56unadulterated energy. The amount of

2:58energy released was so great that if you

3:00add up all the energy of all the stars

3:03burning in the universe,

3:05it was bigger than that.

3:08>> This event was a collision between

3:10relative lightweights,

3:13two stellar mass black holes.

3:18To understand heavyweight bouts, we need

3:21to scale up to super massive black

3:24holes.

3:28In the universe of sports, super massive

3:31black holes are the heavyweight

3:32contenders.

3:33>> With these big black holes, size

3:36matters. The bigger the better.

3:38>> More mass means more energy, which means

3:41more destructive power.

3:43>> We don't need to look too far to find

3:45this devastating muscle. This is M87

3:50star, one of the largest super massive

3:53black holes in our cosmic zip code.

3:57M87 star is huge. It weighs about 6

4:01billion solar masses, about 6 billion

4:03suns, and it's the size of our solar

4:05system.

4:07>> A collision between two 6 billion solar

4:10mass super massive black holes would

4:12release around 5 * 10 to the power of 56

4:16jewels.

4:17So, what's that mean in real world

4:20terms?

4:21>> It's hard to use words to express how

4:23much energy this is. And the numbers are

4:25so huge they're almost meaningless. The

4:27only way I can really explain this is

4:33in physics we have these comparisons so

4:36we can get a mental picture. But for

4:38something like this there is no mental

4:40picture that is so freaking big.

4:46>> So where does this destructive mass and

4:48energy come from?

4:54It starts with the simplest ingredient,

4:58hydrogen.

5:01Hydrogen is the basic building block of

5:04the universe.

5:06Each atom is tiny, but it contains a lot

5:10of energy.

5:11>> Hydrogen atoms contain a huge amount of

5:14energy, just like all matter does. And

5:16if it's unlocked in a certain way, there

5:19can be huge explosions.

5:23I mean, you take the mass contained

5:25simply in my hand and you could blow up

5:27pretty much the entire Earth.

5:29>> Matter has energy because it formed from

5:33energy in the early moments of the

5:35universe.

5:36>> In many ways, atoms are reservoirs of

5:39stored energy from the Big Bang.

5:43>> 13.8 8 billion years ago, the universe

5:47ignites at a super hot ball of intense

5:51energy.

5:53Right after the Big Bang, there's a

5:54tremendous amount of energy. So much

5:56energy, in fact, that normal atoms can't

5:58exist.

6:01>> As that early energy starts to cool, it

6:04can start to form primitive matter.

6:09The universe takes that first matter and

6:12energy in the form of hydrogen atoms and

6:15starts the process of creating a super

6:18massive black hole. Step one, build

6:22giant stars.

6:24>> So, gravity brings together gas, dust,

6:27hydrogen, all of that stuff. And as the

6:30clouds become more dense, they attract

6:32even more material.

6:34>> As they spin, they get hotter and

6:36hotter. And as that temperature and

6:39pressure increase, finally it ignites

6:42nuclear fusion within the core and

6:44creates an actual star.

6:48These huge stars are like cosmic rock

6:51stars. They live fast and die young.

6:55When they die, they flame out in a huge

6:58explosion,

7:00a supernova.

7:02The entire star turns itself inside out

7:07and releases a shock wave going a good

7:10fraction of the speed of light and

7:12releases enough energy to just

7:14obliterate you.

7:17If the dying star is more than 15

7:20stellar masses, its core collapses into

7:23a black hole.

7:26>> It's kind of astounding what the

7:27universe is doing. It's taking

7:28incredibly simple things like hydrogen

7:30atoms and using gravity to ultimately

7:33bring all this stuff together and make

7:35things like black holes.

7:37>> I find it quite beautiful how our whole

7:40cosmic history is the story of little

7:43things coming together into bigger

7:45things.

7:46>> But these stellar mass black holes are

7:49tiny flyweights. To step up to the

7:51heavyweight division, they have to grow

7:54billions of times more massive. But how?

7:58>> How do black holes become super massive?

8:02This is the age-old question. We're not

8:05really sure.

8:07>> The current state-of-the-art

8:09understanding of how black holes become

8:11super massive is like uh we're confused.

8:14Really don't know.

8:16>> We still don't know exactly how they

8:18become so big.

8:21But we do know that the process involves

8:24ultraviolence, death, and destruction.

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What Happens When Two Black Holes Collide?! | How the Universe Works | Science Channel

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