the largest things in the universe are
black holes in contrast to things like
planets or Stars they have no physical
size limit and can literally grow
endlessly although in reality specific
things need to happen to create
different kinds of black holes from
really tiny ones to the largest single
things in the universe so how do black
holes grow and how large is the largest
of them all
[Music]
this video will not discuss how black
holes work or how they form since we've
looked at that in detail in our black
hole and neutron star series you can
check them out afterwards for now we're
interested in finding the largest thing
in the universe let's start really
really small primordial black holes the
smallest kind of black holes may or may
not exist if they do they're probably
the oldest objects in the universe older
even than atoms they would have formed
just after the big bang when the
universe was so dense with violent
energy that any tiny pocket that was
just slightly more dense than its
neighbors could produce a black hole the
smallest primordial black hole that
could still be around would be a
trillion kg or so the mass of a big
mountain and yet they would be no bigger
than a proton a primordial black hole
with the mass of Earth would barely be
larger than a coin this makes them very
hard to find so we haven't actually
observed any yet if they exist they may
even be the mysterious dark matter that
holds galaxies together let's move on to
the kinds of black holes that we know
for sure are out there Stellar black
holes to make a black hole we need to
compress enough matter so that it
collapses into itself after that the
more mass we throw at it the larger it
becomes in today's Universe only the the
most violent Cosmic events can create
the necessary conditions such as the
merger of neutron stars or when the core
of a very massive star collapses in a
supernova to have a unit to work with
here we'll use the mass of our sun about
2 million trillion trillion
kilg the smallest known black hole has
2.7 times the mass of the sun which
works out as a sphere around 16 km in
diameter large enough to cover Paris
another lightweight black hole is the
companion to the v723 mon Red Giant star
this star is 24 times larger than our
sun 30 million km in diameter and yet
it's thrown around by a tiny black hole
just 17.2 km wide this tiny thing
bullying the star is so much smaller
that we can barely even show them in
comparison one of the largest known
Stellar black holes is m33 X7 it
currently spends its time eating a 70
solar mass blue J giant bit by bit as
all that stolen matter circles towards
the black hole like water going down a
drain friction Heats it up to
temperatures high enough to shine
500,000 times brighter than our sun and
yet X7 is only 1565 solar masses and 92
km wide just big enough to cast a shadow
on
Corsica to grow much larger black holes
have to either devour a lot of stars or
better merge with one another the
instruments that make it possible to
detect these mergers are very new so
we're currently discovering a lot of
exciting things like two massive black
holes that we detected in a Galaxy 17
billion light years away as they spun
around each other violently they
released more energy in the form of
gravitational waves than the combined
light from all the stars in the Milky
Way in 4,400 years the New Black Hole
they formed is 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 15 solar masses and
then there's nothing for a long time
until we suddenly hit black holes that
are millions of times more massive which
is a bit confusing because we had this
idea that black holes are consistently
growing and growing but for the most
massive black holes this process is not
fast enough to explain their existence
today the universe is is simply not old
enough for these super massive black
holes to have formed by eating stars and
merging with each other something else
must have happened to explain how we got
the largest black holes in the universe
we might need the largest stars that
ever existed quazi stars to get a sense
of scale we can compare them to the
largest stars that exist today our sun
is like a grain of sand next to them we
don't know if quasi Stars actually
existed but they're an interesting
concept when it comes to supercharging
Black Hole development the idea is that
the matter in the early Universe was so
dense that quasi Stars could grow to
thousands of times the mass of our sun
the cause of these Stars might have been
crushed by their own weight so much to
actually collapse into black holes while
the star was still forming in contrast
to Stars today that would destroy
themselves in the process inside quasi
Stars a deadly balance could emerge
gravity pressed the super massive star
together feeding the black hole and
heating the material falling in to such
a degree that the radiation pressure
kept the star stable and so these
quickly growing black holes might have
been able to consume the quazi star for
millions of years and grow far bigger
than any modern Stellar black hole black
holes several thousand times the mass of
the Sun and wider than the entire Earth
these black holes might have become the
seeds for super massive black
holes so now we arrive at the kings of
our universe the largest single bodies
in existence the centers of most
galaxies contain a super massive black
hole and they are monstrous in the Milky
Way we have Sagittarius AAR a super
massive black hole with about 4 million
solar masses that is calm and collected
and just does its thing we know it sits
there because we can see a number of
stars being thrown around by a seemingly
empty spot and despite its incredible
Mass its radius is still only 17 times
our sun smaller than most giant stars
but millions of times more
massive because super massive black
holes are so massive and located at the
center of galaxies many people imagine
them as being a bit like the sun in the
solar system an anchor that glues
everything else together and forces it
into an orbit but this is a
misconception while the sun makes up
99.86% of all the mass in the solar
system super massive black holes usually
only have
0.001% of the mass of their Galaxy the
billions of stars in galaxies are not
gravitationally bound to them instead
it's the gravitational effect of dark
matter which holds them together many
super massive black holes aren't gentle
Giants especially when they're feeding
on the clouds of mass in their Galaxy
the one at the center of the BL ler
Galaxy is devouring so much material
that it produces Jets of plasma
accelerated to nearly the speed of light
if Earth were orbiting this huge body it
would seem 115 times larger than our sun
in the sky and we be burnt to a crisp in
seconds by its glowing hot accretion
disc at this point black holes become so
large that stars seem ridiculously tiny
compared to them the Galaxy signus a has
a super massive black hole with 2.5
billion solar masses and 14.7 billion km
wide which would mean that if it took
the place of our Sun it would swallow
all the planets and stretch halfway to
the edge of our solar system it's
devouring so much mass and material that
it turns its disc into a kind of
magnetic funnel spewing gas out making
tremendous radio lobes towering over the
Galaxy half a million light years in
diameter that's 2 and 1/2 Milky Ways
wide another pretty large super massive
black hole sits in the Galaxy messia 87
it has 6.5 billion solar masses and was
the first black hole we got an actual
photo of or rather of the glowing gas
around the edge of a menacing Shadow
this sphere of darkness is so large that
it covers our entire solar system and
yet there is a scale even above these
kinds of objects ultramassive black
holes now we reach the most massive
black holes perhaps the largest single
bodies that will ever exist these black
holes have eaten so much that they've
grown to tens of billions of solar
masses their Gravity the engine for a
quazar an accretion disc shining
brighter than thousands of galaxies Full
of Stars so massive that they deserve a
title of their own Ultra massive black
holes the ultra massive black hole at
the center of Galaxy OJ 287 is 18
billion solar masses it's so big that it
has a super massive black hole nearly 40
times larger than Sagittarius AAR
orbiting it this thing defies
imagination and is really hard to
compare to anything it can comfortably
fit three solar systems side by side
inside of it let's end this insane
competition and get to the King of Kings
ton 618 a black hole that we can observe
consuming Galaxy worth of matter is
shining with the brightness of 100
trillion Stars visible from 18 billion I
light years away it has an incredible 66
billion solar masses a black hole so
large that it would take light a week to
reach the singularity after crossing the
Event Horizon about 11 solar systems
could sit inside of it side by side it
may very well be the largest single body
in the universe but in reality it's
probably even larger since ton 618 is so
far away we only see what it looked like
10 billion years ago in any case black
holes are scary and mysterious and
gigantic they'll be here after
everything else dies and growing larger
and
larger okay now let's do the trip again
from the smallest possible black hole
all the way up to the largest
[Music]
let's try something new today we can
call this behind the lies a short behind
the scenes bit about the necessary
inaccuracies in this video because it's
not really actually possible to rank
black holes like trading cards how so
well while we've cataloged millions of
stars we really only have good data on a
couple of dozen black holes that's
because black hole gazing wasn't really
a thing until 50 years ago and
technically still isn't because we can't
see black holes we can only derive their
properties from studying their
gravitational effects on the matter
around them like the orbit of stars that
come close to them this effect depends
on the mass of the black hole which we
can approximate at the most basic level
with Kepler's laws but this comes with
huge uncertainties and error bars then
we have to convert mass to size next
which brings new uncertainties for
example we calculated the radius from
the mass using the Schwartz Shield
equation which for the sake of
Simplicity assumes black holes are
perfectly round and don't spin a kind of
black hole that doesn't really exist the
real ity is that physics on these scales
is a bit fuzzy so some of the black
holes we talked about here may be way
smaller or way bigger we just don't know
for sure we shimmed around this problem
by comparing different sources with
different kinds of values and using
different mass calculations to arrive at
a standardized list that allowed us to
be as accurate as humanly possible you
can look at all of this in our source
dock as a result this script was written
with the tears of experts we drove crazy
with our obsession for the best values
they could live with in this process
tons of stuff got cut and didn't make it
into the final video but luckily we've
found a way to not waste all of it we've
created a lot of black hole merch
spanning the whole range from somewhat
Bonkers to more serious this way we get
to explore a topic from different angles
and you get to continue having fun with
black holes after this video ends
[Applause]
wait
[Music]