there's hardly anything more bizarre in
space than black holes they're invisible
and always hungry space phenomena
some of them come in unimaginably large
sizes in fact black holes can eat up so
much matter that they keep growing
nearly infinitely
so how are black holes different from
what we imagine what's the largest one
that we've ever discovered and how much
bigger can they grow
to understand how black holes work you
need to understand gravity
to throw a ball to some height you need
to apply a certain amount of force the
same with rockets
only they weigh a lot more than a ball
does a rocket speed has to be greater
than the gravitational attraction of the
earth and this speed to gravity ratio is
known as the escape velocity the minimum
speed needed for a rocket to escape our
planet's gravity is at least 11.2
kilometers per second or about 6.9 miles
per second
but what is the escape velocity of a
black hole
it's either the same as the speed of
light or even greater and since nothing
can move faster than the speed of light
you can't escape a black hole once
you're past its event horizon the
boundary of no return surrounding a
black hole
but if black holes don't let any visible
light out how can we see them
although black holes may seem like empty
regions of space they're anything but
that the fact that we can't see a black
hole itself but rather its influence on
the surrounding matter doesn't mean
there's nothing inside one this is due
to its strong gravitational field
anything inside a black hole is tightly
packed and cannot get away as a black
hole's gravity attracts gas and matter
it creates a swirling area around it
called an accretion disk and because
these different particles around a black
hole move extremely fast they start to
heat up and emit x-rays and gamma rays
so using scientific telescopes and
satellites we can actually detect those
rays and assume there's a black hole out
there
another way to spot a black hole is to
notice the weird motion of interstellar
material and stars that might point to a
strong gravitational field beside them
in fact any object can become a black
hole but you need two major ingredients
to make that happen mass and high
density
to make a black hole out of our sun
you'd have to compress it to a radius of
just three kilometers and to make a
black hole out of the earth you'd need
to squish its mass into a sphere the
size of a small p or less than nine
millimeters in radius
but do such tiny black holes even exist
in theory there could be one atom large
black holes and even smaller ones
they're usually referred to as quantum
black holes or primordial black holes
meaning the smallest of them could be
born just after the big bang but if
these tiny black holes existed they
would have been harmless evaporating
instantly after their creation as they'd
be much hotter than our sun
some scientists speculate that
primordial black holes could be one of
the components of dark matter
but let's leave hypothetical primordial
black holes behind and get down to the
type of black holes we've been able to
observe
we know that stellar black holes exist
for sure and they're usually formed when
a massive star explodes with such power
that it shines brighter than an entire
galaxy of stars the phenomenon is called
a supernova
now similar to how we measure distance
in space which is the distance from
earth to the sun scientists use solar
mass as a unit to measure the most
massive objects in space including black
holes and the massive and ordinary
stellar black hole is about 3 to 10
solar masses
cygnus x1 is just an example of a
stellar black hole and the first one
we've discovered cygnus x1 is located in
our galaxy roughly 7000 light years away
from earth but what's interesting about
it is that it spins nearly at its
maximum rate which is 800 times per
second
even though cygnus x1 has 21 solar
masses it's still quite a small
representative of black holes
next come intermediate mass black holes
and their name speaks for themselves
for a long time intermediate mass black
holes were a missing gap for
understanding black hole evolution but
soon everything might change
this type of black hole is already
larger by a lot as it can have a mass
that's hundreds to thousands of times
bigger than that of our sun in 2006
astronomers stumbled across powerful
x-rays and as you already know it's one
way to detect black holes hiding from
our view
these x-rays were tracked to a dense
star cluster in another galaxy and based
on the luminosity of the received signal
a black hole is estimated to be about 50
000 solar masses
while scientists still don't know if
it's an intermediate mass black hole for
sure lots of signs are there fifty
thousand solar masses may look like a
big number but that's almost nothing on
a scale of supermassive black holes
one of those as with most galaxies sits
right in the middle of the milky way
sagittarius a star has a mind boggling
4.6 million times more mass than the sun
but it's only 17 times larger in fact
it's not that big it could actually sit
within mercury's orbit sagittarius a
star is still located about 26 000 light
years away from us so there's no threat
to our planet or our solar system
in the meantime there are supermassive
black holes in some distant galaxies
that act weird
spotted and captured by nasa's hubble
telescope this abnormally bright quasar
named 3c186
is in a galaxy that sits 8 billion light
years away from earth now we already
know that the central parts of most
galaxies contain a supermassive black
hole but what astronomers found out
about this black hole is it's not quite
in the middle in fact it's located
approximately 35 000 light years away
from the center of its galaxy and that's
further than our sun is from the center
of the milky way
so what could possibly move a black hole
that weighs more than one billion suns
scientists believe that about one to two
billion years ago there was a collision
of two galaxies as they collided the
central black holes of the two galaxies
started to circle each other and
eventually merged into one creating
powerful gravitational waves
as a result a newly formed black hole
was harshly kicked out in the direction
opposite from the strongest
gravitational waves
the power of such a kick was so immense
it could be compared to 100 million
supernovae exploding all at once
3c186 still keeps moving away at the
speed of 7.5 million kilometers per hour
at this speed it could travel from our
planet to the moon in roughly three
minutes
the new black hole that was born should
be much larger than one billion suns but
so far we have no idea how massive it
could be
to grow that big black holes need to
feed on tons of stars but don't
misinterpret that they're not space
vacuum cleaners if our sun was suddenly
replaced with a black hole having the
exact same mass there would be no change
in the earth's orbit and we wouldn't be
swallowed up by it since its radius
would be just three kilometers so we'd
have to be much closer to it than we
currently are
supermassive black holes are already
hard to comprehend but they're miniature
compared to ultra massive black holes
one of the largest and most massive
black holes ever discovered in this
category would make sagittarius a star
look like a small asteroid placed next
to our sun
within the huge galaxy home 15a home to
roughly 2 trillion solar masses lies a
black hole 40 billion times more massive
than our sun
to compare it's more than half of the
stars in our galaxy put together home
15a sits 700 million light years away
from us and a black hole in the heart of
this galaxy equals the size of our
entire solar system
until recently scientists believed that
the upper limit for the massive
illuminous black hole was about 50
billion solar masses little did they
know a new discovery would change this
you may not know this but the brightest
objects in the universe aren't stars or
galaxies quasars are not so long ago a
quasar with the brightness of 140
trillion suns named ton 618 was
discovered
it's so bright that it outshines the
entire galaxy it's located in and the
ultra massive black hole powering it is
a real monster at 66 billion solar
masses
which makes it even more massive than
all the stars combined in the milky way
ton 618 has a diameter of
389.8 billion kilometers the quasar is
located in a distant constellation
canees venatici some 10.4 billion light
years from us because ton 618 is so far
away its light takes more than 10
billion years to reach us so we only see
how big it was when the universe was
just a few billion years old and by this
time it could have grown a lot bigger
one idea is that for such a monstrous
black hole to grow there should have
been a different black hole that served
as a seed to feed a bigger one by
merging with it but computer simulations
show this isn't what happened with ton
618 a more probable scenario would be
multiple black holes merging together
into one over time still we don't know
if that describes the story of how ton
618 formed but it remains the most
massive black hole we've discovered up
to this date
so far we keep finding new black holes
that appear to be larger and larger each
time and scientists have even started
suggesting there could be a new class of
black holes named stupendously large
black holes
these black holes could have a mass
above 100 billion solar masses and even
a lot more than that
all of this begs the question if black
holes constantly grow does this mean
they're eternal
well on a scale of human life the
lifespan of our planet our sun and even
our solar system yes
black holes slowly evaporate and lose a
tiny bit of mass through a process
called hawking radiation
but the thing is it's a very slow
process it'll take about the age of our
universe for a black hole with a mass of
100 million tons to only lose 50 percent
of its mass and the bigger they are the
more this process slows down
once all the stars fade out or explode
black holes will still be there for a
very long time
by the way if you'd like to see a video
about this and how the universe will
little by little freeze and die let us
know in the comments
the observable universe is roughly 46
billion light years in radius so there's
a lot more out there to surprise us
one day we'll hopefully find something
that could shed light on the dark
mysterious patches scattered out there
in the skies
so far it's like trying to guess what's
behind a door while only knowing what
size the room could be and its
temperature we hope you enjoyed this
video and thanks for watching
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