Black holes can destroy everything – but
can they be destroyed? What happens if we push physics to the absolute
limits, maybe even break it and the universe in the process? Let’s create a tiny black hole, about the
mass of our moon, in the Kurzgesagt Labs and try to rip it apart. Nuke It Big booms break things. So to set the mood, let’s explode the world's
entire nuclear arsenal around our black hole! Boom Black holes swallow whatever crosses their
event horizon, matter and energy. And since E = mc2, all the energy that enters
a black hole increases its mass. The mass of a black hole is proportional to
its size, so as we nuke our tiny black hole, it just gets bigger and more massive! Antimatter Matter and antimatter annihilate each other. What will happen if we throw a moon's mass
of antimatter at it? Unfortunately, when an object enters a black
hole, the black hole will completely delete its past identity – whether it’s made
of matter or of antimatter. Black holes only care about gravity, which
only depends on the total mass-energy of an object. And the mass of a particle is the same as
its corresponding antiparticle, so throwing an anti-moon has the same effect as throwing
a moon. The black hole just gets more massive! This “deleting ability” of black holes
is pretty interesting: It means that, despite their size and power, black holes are, in
a way, similar to elementary particles. An elementary particle, like an electron,
is an extremely simple object, fully specified by just three numbers: its mass, spin and
charge. And amazingly, the same is true for black
holes. They have a mass, they can rotate and carry
an electric charge. Once a black hole forms, it doesn't matter
if it came from a collapsed star, an anti-star or a banana: it will always be fully described
by those three numbers, nothing else. But if a black hole is basically a weird particle
– could we destroy it with an anti black hole? Anti Black Hole How exciting! A particle has the same mass as its corresponding
antiparticle but opposite charge. Since a black hole has mass and electric charge,
its corresponding anti black hole should have the same mass and opposite electric charge. What if we make them collide? Sadly, the charge will just add up and cancel
out. So after the collision, we’ll just get a
new black hole twice as massive with no charge. OK. We need to think bigger and stretch physics
harder. Destroy the Event Horizon It is true that a black hole can carry spin
and charge. But even for these crazy objects, there are
limits. If the spin or the charge of a black hole
becomes too large, something really weird will happen: the event horizon will dissolve. In a simplified way, we think of black holes
as hiding a singularity inside – an infinitely compressed mass with such strong gravity that
absolutely nothing can escape from its surroundings, not even light. This is why a black hole looks like a “black
sphere of nothingness”. The event horizon is the outer edge of this
ultimate prison. Cross it, and you’ll never be able to come
back. But when a black hole rotates, it works a
bit like a spinning washing machine. It is as if the rotation wants to repel nearby
objects and push them out of the black hole – which doesn’t happen because its gravity
is so strong. BUT – If the rotation gets too fast, this
effect will win and the event horizon will disappear – nearby objects won’t be imprisoned
forever anymore! The same thing happens with the electric charge. Make it too large, and our ironclad jail will
break open. If we managed to destroy the event horizon,
the singularity would still be there. And objects would still naturally fall towards
it. If you hit it, you would still die horribly
and quickly. But the vicinity of the singularity won’t
be an inescapable prison anymore! You could get as close as you want and come
back. This should count as destroying the black
hole! Can we do it? Overfeeding All we have to do is to overcharge or over-spin
the black hole. We could do this by throwing objects with
a small mass and a lot of charge or angular momentum, so that the charge or spin increases
faster than the mass. We have to overfeed the black hole until it
reaches the point where it breaks open. However, whether you can actually do this
is the subject of passionate argument among physicists. Think of a charged black hole. Equal charges repel each other, and the more
of the same charges you squish together, the more they push back. So let’s say that we have a negatively charged
black hole and we want to overfeed it with electrons, for example, whose charge is far
larger than its mass. The electrons will feel an electrostatic repulsion. And the more electrons we throw, the larger
the negative charge of the black hole will be and the stronger the repulsion. But once we reach the upper limit, the electrostatic
repulsion will be so strong that it won't allow any more electrons to come in. At this point, the black hole will refuse
to be overfed. With the spin it works similarly. Once the black hole reaches its upper limit,
it won’t gobble more spin. But some scientists have discovered what looks
like a loophole. If an instant before the black hole reaches
the limit, we throw the right amount matter in just the right way, it looks like we could
actually overfeed it. Most scientists are skeptical, but let's give
it a try anyway! Breaking Physics There is a catch though. The event horizon of a black hole hides the
singularity. So destroying the horizon would leave us with
a “naked singularity”, one that is not hidden by an event horizon. And this poses a problem: it could mean the
end of physics as we know it. There is a big dirty secret about black holes. Contrary to widespread belief, the singularity
of a black hole is not really “at its center”. No. It is in the future of whatever crosses the
horizon. Black holes warp the universe so drastically
that, at the event horizon, space and time switch their roles. Once you cross it, falling towards the center
means going towards the future. That’s why you cannot escape: Stopping your
fall and turning back would be just as impossible as stopping time and traveling to the past. So the singularity is actually in your future,
not “in front of you”. And just like you can’t see your own future,
you won’t see the singularity until you hit it. But you also can’t hit something that is
in your future, only sort of… experience it, like you will experience your next birthday
when it happens. So you will feel the singularity once it happens
to you. Singularities that are in the future are not
a problem because we can’t see them or interact with them. But a naked singularity would be in front
of us, for all of us to see. What would we see? Well, the whole point is that it’s impossible
to know. A singularity is a region of infinite gravity,
and gravity is the bending of spacetime. At a singularity, the bending is so radical
that the fabric of spacetime is literally broken. Space and time don’t exist anymore. This means that you cannot predict anything,
since predicting means making a forecast about where and when something will happen. But “where” and “when” have lost their
meaning! So we have an unpredictable thing with infinite
gravity, and therefore infinite energy. This means that anything could come out of
it for no reason – from a pile of bananas, to lost socks or a solar system. Predictability, causality and physics as we
know it would break down. We think that singularities should exist in
nature because we can prove that, under very general conditions, gravitational collapse
leads to the formation of singularities. However, scientists think that nature forbids
the formation of naked singularities. Something enforces the creation of an event
horizon around them, to prevent their insanity from infecting the rest of the universe. Without event horizons, physics may not make
sense at all. So although black holes have been portrayed
as the ultimate monsters of the universe, they may actually be the heroes that keep
us safe from the madness of singularities. So if we do destroy the horizon, we might
destroy the fundamental rules of the universe. You know what? Let’s not do that. The Safe Option As far as we know, there’s just one safe
method to destroy a black hole: Wait. All black holes emit tiny particles – a
phenomenon called Hawking radiation. This process causes them to slowly lose mass
until they eventually “evaporate”, leaving behind no horizon and no naked singularity. The time it takes for a black hole to completely
evaporate depends on its mass. For our mini black hole the size of a speck
of dust, it will be about 10^44 years: 10 billion trillion trillion times the present age of
the universe. So, is it possible to destroy a black hole? Yes! We just have to wait. But you don’t have to wait that long. There are plenty of fascinating things to
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