black holes only seem to come in two radically different sizes they're either around five to a
hundred times the mass of our sun what are called stellar mass black holes or they're millions to
billions of times more massive than our sun aptly named supermassive black holes so what is going on
here where are all the in-between sized black holes and why does the scale range stop there
could black holes be really tiny or even as new research suggests stupendously large you may
remember when the large hadron collider was first coming online some alarmists claimed it would
create a black hole that would destroy the earth while microscopic black holes seem far-fetched
there are some theoretical ways they could exist but you'd need extra dimensions to do it
gravity as we know it isn't strong enough to compress subatomic particles small enough
to make them collapse into a black hole because that size is smaller than the smallest meaningful
measurement of distance the plank length if discovered microscopic black holes would change
our understanding of how gravity works at the quantum scale and even imply the existence of
extra dimensions that amplify gravity's force so microscopic black holes could be made in particle
accelerators but they would also exist for only the briefest of moments decaying in an octillionth
of a nanosecond not exactly enough time to devour the entire planet so if they do exist they're
nothing to lose sleep over stellar mass black holes though are very much real and we have a
pretty solid understanding of how they form when large stars run out of fuel they collapse and go
supernova if the core they leave behind is more than about three solar masses the star's remnants
collapse in on themselves and a black hole is born these black holes can grow by devouring nearby
material or merging with neutron stars or other black holes you might imagine if a stellar mass
black hole was allowed to just keep accumulating matter eventually it would balloon to the size
of the supermassive black holes that we think are at the center of almost all large galaxies
but there's an upper limit to how fast matter can fall into a black hole so growing that large would
take billions of years since we've observed black holes with billions of solar masses that formed
within hundreds of millions of years of the big bang something else must be at work the mechanism
for how supermassive black holes come to be is one of the great mysteries of astronomy there are a
few competing ideas each with their own strengths and weaknesses for example maybe they formed from
large seed black holes that are already very massive when they form and then they continue
to grow as they suck in matter these large seeds would be the remnants of stars as big as 250
000 solar masses stars that large should be rare making large seeds less likely another idea is
they're the product of several intermediate-sized black holes these intermediate-sized black holes
could form in dense star clusters as stars collide after formation they sink toward the
center of a galaxy where they merge as i said before though there seems to be a gap in the
sizes of black holes there is very little evidence that intermediate-sized black holes exist beyond
supermassive black holes there could be even more jumbo cosmic pits one recent suggestion is
there could be black holes larger than a trillion solar masses more than 10 times larger than even
the very biggest black hole we've discovered the researchers who proposed their existence
dubbed them stupendously large black holes even our explanations for supermassive black holes
wouldn't account for these giants their existence would require us to rethink how black holes form
or maybe there just is an upper limit to how big black holes can get black holes could
run the gamut from the microscopic to the mind meltingly massive but so far the only thing we
know for sure is they exist in two size ranges and we're not even certain how the larger size
is possible there's no doubt scientists are going to keep probing for black holes at all scales
because black holes have not only captured light but our imaginations too you might think that
stupendously large black holes are the result of when supermassive black holes combine but
something called the final parsec problem makes their merger impossible check out my video on that
here all right wild hypothesis time where do you think all the intermediate-sized black holes are
let us know your thoughts in the comments be sure to subscribe and i'll see you next time on seeker