Longtime viewers of this channel know that
we talk about black holes a lot.
We just can’t seem to get enough of them.
We give them so much attention but today we’re
going to talk about their bizarro twins, white
holes.
Basically, a white hole is the hypothetical
opposite of a black hole.
Now I’d bet that you know what a black hole
is, but hey, they still have to explain seat
belts every time you fly on an airplane, so
buckle up because after the refresher we’re
going on a wild ride.
Black holes are regions of space where so
much mass is packed together so densely it
forms what’s called a singularity, and nothing
can move fast enough to escape its gravitational
pull.
Not even the fastest thing in the universe,
light, can escape its clutches.
But you knew that right?
Everybody knows what a black hole is… except
that nobody knows what a black hole is, not
exactly anyway.
Because of that pesky fact that light can’t
escape, we can’t see what’s going on inside
a black hole.
So we have to rely on theories and equations
to deduce what’s happening at the center
of the event horizon, and that has been a
major sticking point in physics.
There are two competing explanations to describe
black holes.
One of them is Einstein’s theory of general
relativity, where the mass of a black hole
bends spacetime so much that it becomes one
single point of infinite density.
On the other hand, according to quantum mechanics
there can’t be an infinitely small point.
It can be very very small, but not infinitely
so.
And this irreconcilable difference is one
of the greatest debates in physics, since
general relativity is our best description
of gravity, while quantum mechanics has been
called the most successful theory ever.
But some physicists believe white holes could 
square these two predictions and reveal what’s
happening inside a black hole.
The equations of general relativity allow
for the possibility of white holes, all you
have to do is set the mass of the singularity
to zero and everything gets turned on its
ear.
Instead of a cosmic vacuum that sucks up everything
that strays too close, you get a… whatever
the opposite of a vacuum is?
I’m not good with metaphors, but the point
is all it can do is spew stuff out.
But then the question is, how do you get a
singularity, a point of infinite density remember,
with no mass?
And how does a massless singularity spit anything
out?
Because of that head scratcher white holes
have long been written off as a mathematical
quirk but not something that can happen in
reality.
However, quantum mechanics allows for some
“adjustments” to the solutions of the
equations of general relativity, and with
those adjustments, the interior of a black
hole could transform into a white hole.
One physicist describes it as though the curved
spacetime of the black hole itself is bouncing
out again, and this rebound opens up some
tantalizing possibilities.
Since a black hole might transform into a
white hole, that means things falling into
it may come out again.
This would solve another issue quantum physics
has with black holes because in quantum physics
information cannot be destroyed.
Granted, whatever came out of a white hole
would be a very mangled version of its former
self, but nonetheless, information about what
it was would not be deleted from the universe.
It sounds like a wormhole, but instead of
traveling through space, the object would
travel through time.
General relativity tells us that time moves
more slowly near massive objects, so to an
object falling into the black hole it would
seem like very little time is passing, but
to an outside observer, it would take ages
to pop out again on the rebound.
Just how far into the future it travels depends
on the size of the black hole, with big holes
taking quadrillions of times the age of the
universe to transition.
But small black holes that formed just after
the chaos of the Big Bang may have already
converted.
They would be invisible because they’d be
smaller than the wavelength of light, but
have the mass of about a millionth of a gram.
White hole proponents say this could make
them an attractive candidate for dark matter.
Yeah, the upsides of white holes just keep
getting better and better.
I told you it would be a wild ride but here is where it comes to an end.
I have to remind you that white holes are
still purely hypothetical.
The math checks out and the reasons to hunt
for them are numerous, but at this stage they
remain a very unexplored corner of physics.
Then again, there was a time when the same
could be said about black holes.
We’re just going to need a few physicists
dedicated enough to the idea of white holes
to keep searching for them.
That or a few brave volunteers to jump into
a black hole. huh?
Who’s going with me, huh?
Anyone?...Anyone?
White holes may form faster when the black
holes are less massive, but black holes themselves
can merge and get bigger.
There’s a debate whether the very biggest
supermassive black holes can come together
and for more on that check out my
video here.
Alright, so I mean it. Who's jumping in with me huh?!
Who's going in the nearest black hole?!
Let us know down in the comments below. Be sure to subscribe to Seeker,
and I will see you next time.
