The Largest Black Hole in the Universe - Size Comparison

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Reddit Comments

The "behind the lies" bit at the end was really great!

šŸ‘ļøŽ︎ 35 šŸ‘¤ļøŽ︎ u/N8CCRG šŸ“…ļøŽ︎ Aug 03 2021 šŸ—«︎ replies

"This process is not fast enough to explain their existence today. The universe is simply not old enough to have formed for these supermassive black holes by eating stars and merging with each other."

So there are black holes so large that we have no idea at the moment what could have happened to cause them, aside from the possible existence of a theoretical star? Interesting.

šŸ‘ļøŽ︎ 221 šŸ‘¤ļøŽ︎ u/amostlyghostlyghost šŸ“…ļøŽ︎ Aug 03 2021 šŸ—«︎ replies

Ah yes, the weekly dose of existential dread.

šŸ‘ļøŽ︎ 282 šŸ‘¤ļøŽ︎ u/Frexxia šŸ“…ļøŽ︎ Aug 03 2021 šŸ—«︎ replies

I don't think I've experienced Eldritch terror until Ton 618 was depicted.

šŸ‘ļøŽ︎ 97 šŸ‘¤ļøŽ︎ u/RunJun šŸ“…ļøŽ︎ Aug 03 2021 šŸ—«︎ replies

Me : "Surely they can't get any bigger, right?"

Kurzgesagt : "Lol"

Me : "..."

šŸ‘ļøŽ︎ 70 šŸ‘¤ļøŽ︎ u/ashlynnrariity šŸ“…ļøŽ︎ Aug 03 2021 šŸ—«︎ replies

Kurzgezagt is so great.

šŸ‘ļøŽ︎ 35 šŸ‘¤ļøŽ︎ u/Demurist šŸ“…ļøŽ︎ Aug 03 2021 šŸ—«︎ replies

The song composed for the video is on Spotify, in case anyone else wondered

https://open.spotify.com/track/479piqfYJyfsuQ74HY9TMB?si=mxTM5jC6RbGkVxffXhuvdg&utm_source=copy-link&dl_branch=1

šŸ‘ļøŽ︎ 21 šŸ‘¤ļøŽ︎ u/Frexxia šŸ“…ļøŽ︎ Aug 03 2021 šŸ—«︎ replies

I sincerely hope they show these videos in classes. The visuals are so perfect for explaining more abstract concepts to people. Including myself!

šŸ‘ļøŽ︎ 23 šŸ‘¤ļøŽ︎ u/appleparkfive šŸ“…ļøŽ︎ Aug 03 2021 šŸ—«︎ replies

The fact that the radius grows linearly with mass instead of mass1/3 still deeply confuses me

Edit: Imagine a woodmouse with a length of 10 cm and a weight of 20 g. If woodmice behaved like black holes, feeding the mouse until it was the mass of a human (100 kg) would not make it the size of a human -- it would grow to be 500 metres long! And in the same proportions as when it was mouse-sized!

šŸ‘ļøŽ︎ 12 šŸ‘¤ļøŽ︎ u/QCD-uctdsb šŸ“…ļøŽ︎ Aug 03 2021 šŸ—«︎ replies
Captions
The largest things in theĀ  universe are black holes.Ā Ā  In contrast to things like planets orĀ  stars they have no physical size limit,Ā Ā  and can literally grow endlessly. Although inĀ  reality specific things need to happen to createĀ Ā  different kinds of black holes, from really tinyĀ  ones to the largest single things in the universe.Ā Ā  So how do black holes grow and howĀ  large is the largest of them all? This video will not discuss how black holes workĀ  or how they form since weā€™ve looked at that inĀ Ā  detail in our black hole and neutron star series,Ā  you can check them out afterwards. For now we areĀ Ā  interested in finding the largest thing in theĀ  universe. Let us start really, really small. Primordial Black holes The smallest kind of black holes may or may notĀ  exist. If they do, they are probably the oldestĀ Ā  objects in the universe, older even than atoms.Ā  They would have formed just after the big bang,Ā Ā  when the universe was so dense withĀ  violent energy, that any tiny pocketĀ Ā  that was just slightly more dense thanĀ  its neighbors could produce a black hole. The smallest Primordial Black Hole thatĀ  could still be around would be a trillionĀ Ā  kilograms or so, the mass of a big mountain.Ā  And yet they would be no bigger than a proton.Ā Ā  A Primordial Black hole with the mass ofĀ  earth would barely be larger than a coin.Ā Ā  This makes them very hard to find, so weĀ  havenā€™t actually observed any yet ā€“ ifĀ Ā  they exist they may even be the mysteriousĀ  dark matter that holds galaxies together. Letā€™s move on to the kinds of black holesĀ  that we know for sure ARE out there. Stellar Black Holes To make a black hole we need to compress enoughĀ  matter so that it collapses into itself. AfterĀ Ā  that, the more mass we throw at it, theĀ  larger it becomes. In today's universe,Ā Ā  only the most violent cosmic events can createĀ  the necessary conditions, such as the merger ofĀ Ā  neutron stars or when the core of a very massiveĀ  star collapses in a supernova. To have a unit toĀ Ā  work with here, weā€™ll use the mass of our sun,Ā  about 2 million trillion trillion kilograms. The smallest known black holeĀ  has 2.7 times the mass of the sunĀ Ā  which works out as a sphere around 16 kmĀ  in diameter, large enough to cover Paris. Another lightweight black hole is theĀ  companion to the V723 Mon red giant star.Ā Ā  This star is 24 times larger than our sun,Ā  30 million kilometer in diameter. And yet,Ā Ā  it is thrown around by a tiny black holeĀ  just 17.2 km wide. This tiny thing bullyingĀ Ā  the star is so much smaller that we canĀ  barely even show them in comparison. One of the largest known stellar black holes isĀ  M33 X-7. It currently spends its time eating a 70Ā Ā  solar mass blue giant, bit by bit. As all thatĀ  stolen matter circles towards the black hole,Ā Ā  like water going down a drain, friction heatsĀ  it up to temperatures high enough to shineĀ Ā  500,000 times brighter than our Sun! AndĀ  yet, X-7 is ā€˜onlyā€™ 15.65 solar massesĀ Ā  and 92 km wide, just big enoughĀ  to cast a shadow on Corsica. To grow much larger, black holes have to eitherĀ  devour a lot of stars or better, merge with oneĀ Ā  another. The instruments that make it possibleĀ  to detect these mergers are very new so we areĀ Ā  currently discovering a lot of exciting things.Ā  Like two massive black holes that we detected inĀ Ā  a galaxy 17 billion lightyears away. As they spunĀ  around each other violently, they released moreĀ Ā  energy in the form of gravitational waves than theĀ  combined light from all the stars in the milky wayĀ Ā  in 4400 years. The new black hole they formed isĀ  about the size of Germany and is 142 solar masses. And here we hit a curious gap in scale. There are lots of black holes up to 150 solarĀ  masses. And then there is nothing for a longĀ Ā  time. Until we suddenly hit black holes,Ā  that are millions of times more massive. Which is a bit confusing, because we had thisĀ  idea that black holes are consistently growingĀ Ā  and growing. But for the most massive black holesĀ  this process is not fast enough to explain theirĀ Ā  existence today. The universe is simply notĀ  old enough for these supermassive black holesĀ Ā  to have formed by eating stars and merging withĀ  each other. Something else must have happened. To explain how we got the largest blackĀ  holes in the universe, we might need theĀ Ā  largest stars that ever existed: Quasi Stars.Ā  To get a sense of scale, we can compare themĀ Ā  to the largest stars that exist today. OurĀ  Sun is like a grain of sand next to them. We donā€™t know if Quasi Stars actually existed butĀ  they are an interesting concept when it comes toĀ Ā  supercharging black hole development. The idea isĀ  that the matter in the early universe was so denseĀ Ā  that quasi stars could grow to thousands ofĀ  times the mass of our sun. The cores of theseĀ Ā  stars might have been crushed by their own weightĀ  so much to actually collapse into black holesĀ Ā  while the star was still forming. In contrast toĀ  stars today that would destroy themselves in theĀ Ā  process, inside quasi stars, a deadly balanceĀ  could emerge. Gravity pressed the supermassiveĀ Ā  star together, feeding the black hole and heatingĀ  the material falling in to such a degree that theĀ Ā  radiation pressure kept the star stable. And soĀ  these quickly growing black holes might have beenĀ Ā  able to consume the quasi star for millions ofĀ  years and grow far bigger than any modern stellarĀ Ā  black hole. Black holes several thousand times theĀ  mass of the Sun and wider than the entire earth. These black holes might have becomeĀ  the seeds for supermassive black holes. Supermassive black holes So now, we arrive at the kings of ourĀ  universe, the largest single bodies inĀ Ā  existence. The centers of most galaxies contain aĀ  super massive black hole, and they are monstrous. In the Milky Way we have Sagittarius AĀ  Star, a super massive black hole withĀ Ā  about 4 million solar masses that is calm andĀ  collected and just does its thing. We knowĀ Ā  it sits there because we can see a number of starsĀ  being thrown around by a seemingly empty spot.Ā Ā  And despite its incredibleĀ  mass, itā€™s radius is stillĀ Ā  only 17 times our sun. Smaller than most giantĀ  stars, but millions of times more massive. Because Supermassive black holes are soĀ  massive and located at the center of galaxies,Ā Ā  many people imagine them as being a bit likeĀ  the Sun in the solar system. An anchor thatĀ Ā  glues everything else together and forces it intoĀ  an orbit. But this is a misconception. While theĀ Ā  sun makes up 99.86% of all the mass in the solarĀ  system, SuperMassive Black Holes usually only haveĀ Ā  0.001% of the mass of their galaxy. The billionsĀ  of stars in galaxies are not gravitationallyĀ Ā  bound to them, instead it is the gravitationalĀ  effect of dark matter which holds them together. Many supermassive black holes arenā€™t gentleĀ  giants, especially when they are feeding onĀ Ā  the clouds of mass in their galaxy. The one at theĀ  center of the BL Lacertae galaxy is devouring soĀ Ā  much material that it produces jets of plasmaĀ  accelerated to nearly the speed of light.Ā Ā  If Earth were orbiting this huge body, it wouldĀ  seem 115 times larger than our Sun in the skyā€¦Ā Ā  and weā€™d be burnt to a crisp in secondsĀ  by its glowing hot accretion disk. At this point black holes become so large thatĀ  stars seem ridiculously tiny compared to them. The galaxy Cygnus A has a super massive black holeĀ  with 2.5 billion solar masses and 14.7 billion kmĀ Ā  wide, which would mean that if it took the placeĀ  of our Sun, it would swallow all the planets andĀ Ā  stretch halfway to the edge of our Solar System.Ā  It is devouring so much mass and material that itĀ Ā  churns its disk into a kind of magnetic funnel,Ā  spewing gas out making tremendous radio lobes,Ā Ā  towering over the galaxy, half a million lightĀ  years in diameter. That is 2.5 Milkyways wide. Another pretty large Super Massive BlackĀ  hole sits in the galaxy Messier 87. ItĀ Ā  has 6.5 billion solar masses and was theĀ  first black hole we got an actual photo of.Ā Ā  Or rather of the glowing gas aroundĀ  the edge of a menacing shadow.Ā Ā  This sphere of darkness is so largeĀ  that it covers our entire Solar System. And yet, there is a scale evenĀ  above these kinds of objects... Ultramassive black holes Now we reach the most massive black holes, perhapsĀ  the largest single bodies that will ever exist.Ā Ā  These black holes have eaten so much that they'veĀ  grown to tens of billions of solar masses, theirĀ Ā  gravity the engine for a ā€˜quasarā€™- an accretionĀ  disk shining brighter than thousands of galaxiesĀ Ā  full of stars. So massive that they deserve aĀ  title of their own - Ultramassive Black Holes. The Ultra Massive Black Hole at the center ofĀ  galaxy OJ 287 is 18 billion solar masses. ItĀ Ā  is so big that it has a Super Massive black hole,Ā  nearly forty times larger than sagittarius A star,Ā Ā  orbiting it! This thing defies imaginationĀ  and is really hard to compare to anything.Ā Ā  It can comfortably fit three SolarĀ  Systems side by side inside of it. Let us end this insane competitionĀ  and get to the king of kings. TON 618, a black hole that we can observeĀ  consuming galaxies worth of matter isĀ Ā  shining with the brightness of a hundred trillionĀ  stars, visible from 18 billion light years away.Ā Ā  It has an incredible 66 billion solar masses.Ā  A black hole so large that it would take lightĀ Ā  a week to reach the singularity afterĀ  crossing the event horizon. About 11Ā Ā  Solar Systems could sit inside of it sideĀ  by side. It may very well be the largestĀ Ā  single body in the universe. But inĀ  reality, it is probably even larger.Ā Ā  Since TON 618 is so far away, we only seeĀ  what it looked like 10 billion years ago. In any case, black holes are scary and mysteriousĀ Ā  and gigantic. They will be here after everythingĀ  else dies, and growing larger and larger. So now let us do the trip again. FromĀ  the smallest possible black hole,Ā Ā  all the way up to the largest. Letā€™s try something new today,Ā  we can call it: ā€œBehind the Liesā€Ā Ā  a short behind the scenes bit about theĀ  necessary inaccuracies in this videoĀ Ā  because it's really not actually possibleĀ  to rank black holes like trading cards. How so? Well, while we have cataloguedĀ  millions of stars, we really only haveĀ Ā  good data on a couple of dozen black holes.Ā  Thatā€™s because black hole gazing wasnā€™t reallyĀ Ā  a thing until 50 years ago ā€“ and technicallyĀ  still isnā€™t, because we canā€™t see black holes. We can only derive their properties from studyingĀ  their gravitational effects on the matter aroundĀ Ā  them, like the orbit of stars that come closeĀ  to them. This effect depends on the mass of theĀ Ā  black hole, which we can approximate atĀ  the most basic level with Keplerā€™s Laws.Ā Ā  But this comes with hugeĀ  uncertainties and error bars.Ā Ā  Then we have to convert mass to sizeĀ  next, which brings new uncertainties.Ā Ā  For example, we calculated the radius from theĀ  mass using the Schwarzschild equation which forĀ Ā  the sake of simplicity assumes black holes areĀ  perfectly round and donā€™t spin: a kind of blackĀ Ā  hole that doesnā€™t really exist. The reality isĀ  that physics on these scales is a bit fuzzy. So some of the black holes we talked aboutĀ  here may be way smaller or way bigger. WeĀ Ā  just donā€™t know for sure. We shimmied aroundĀ  this problem by comparing different sourcesĀ Ā  with different kinds of values and usingĀ  different mass calculations to arriveĀ Ā  at a standardized list that allowed usĀ  to be as accurate as humanly possible.Ā Ā  You can look at all of this in our source doc. AsĀ  a result this script was written with the tears ofĀ Ā  experts we drove crazy with our obsessionĀ  for the best values they could live with. In this process, tons of stuffĀ  got cut and didnā€™t make it intoĀ Ā  the final video ā€“ but luckily weĀ  found a way to not waste all of it: We created a lot of black hole merch, spanning theĀ  whole range from somewhat bonkers to more serious.Ā Ā  This way we get to explore a topicĀ  from different angles ā€“ and youĀ Ā  get to continue having fun withĀ  black holes after this video ends.
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Channel: Kurzgesagt ā€“ In a Nutshell
Views: 3,446,204
Rating: 4.9751182 out of 5
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Id: 0FH9cgRhQ-k
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Length: 13min 43sec (823 seconds)
Published: Tue Aug 03 2021
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