How Small Is A Mini Black Hole?

Black holes have a gravitational force that can consume all that comes within reach of the event horizon. When you think of that, even a mini black hole sounds absolutely terrifying.

But what exactly is the size of these mini-monsters, and could even a micro black hole pose a threat?

The mini black hole can be anywhere in size between three stellar masses and smaller than an atom — if they exist. Find out more with this guide. 

How Small Is A Mini Black Hole?

When we think of black holes, we picture something large and powerful. Standard black hole mass is between 3 and 10 solar masses, while a supermassive black hole might have a mass equal to a billion solar masses.

They also have an intense gravity, so strong that nothing can escape, including light. This is the reason they appear black and have no detectable features.

Mini black holes are very different and must be less than three solar masses. But that’s the upper limit.

The minimum size for a micro black hole is theorized by Stephen Hawking to be 0.00000001 kg, or roughly the Planck mass, which is a universal constant.

So, a micro black hole could, theoretically, exist between 0.00000001 kg, and the total mass of three stars. Which is quite a range of sizes.

The size would also determine the lifespan and the gravitational force, causing some big behavioral differences between these and their larger counterparts. 

However, this is assuming that even at small distances, the theory of general relativity holds true. And if it doesn’t, then the minimum size of a micro black hole would be something else entirely. 

What Is A Mini Black Hole?

A mini black hole is similar to a standard black hole, only smaller. However, as black holes are heavily dependent on an extreme amount of mass and gravity,

a smaller version could have some new properties. And they could change our understanding of quantum mechanics.

Black holes are formed when massive stars reach the end of their life cycle and collapse in on themselves.

The mass of the star becomes incredibly compact, causing a gravitational pull so strong that nothing can escape. This point of no return is known as an event horizon.

There’s also no upper limit on the size of a black hole. When black holes merge and absorb mass from nearby stars,

this is known as a supermassive black hole. And these can keep on going until they become ultra-massive black holes.

At the other end of the scale is the micro or mini black hole. This is also sometimes known as the quantum mechanical black hole. 

Mini black holes would share some similar properties with the standard black hole while also being markedly different.

For a start, the creation of the smallest mini black hole would rely on the idea that gravity becomes significantly stronger over miniscule distances.

This would change the Schwarzschild radius, which describes the limit at which gravity would cause a density to collapse.

A mini black hole would also be intensely hot, causing them to evaporate quickly and pop out of existence before a nanosecond has passed.

A standard black hole, on the other hand, decays slowly. Although, they are all theorized to eventually evaporate.

Even more unusually, it’s been theorized that a micro-black hole might not actually be that black.

Could A Mini Black Hole Destroy The Earth?

Matter that passes beyond the event horizon of a black hole does not come back. Even light can’t make its way back from a black hole, and stars can find themselves sucked in. Pretty terrifying, right?

Mini black holes aren’t quite so scary, but they still have the potential to do some serious damage.

Black holes are mass compacted into a dense area. A black hole with the mass of the Earth would be less than an inch and probably the size of a coin.

A black hole with the mass of Mount Everest would be smaller than a nanometer.

For these black holes to cause any damage, they’d need to get very close to Earth. Too far away, and the gravitational pull just isn’t that strong. This is the same reason we don’t fall into the Sun. 

So, even the largest of the mini black holes aren’t too worrying.

But what about mini black holes created on Earth? Such as those supposedly being made by the Large Hadron Collider?

To start with, the Large Hadron Collider was not built to create black holes. The energy needed to create a black hole is intense and not something that could be achieved in our particle accelerators.

If the LHC were to create a black hole, it would be because gravity behaves differently on a very small scale. And any micro-black hole created could be tiny as in, smaller than an atom.

A mini black hole would have a corresponding mini-event horizon. For a lab-grown black hole, that would be even smaller than an atom.

This would allow the mini black hole to pass through Earth and never get close enough for an atom to come under threat from the gravitational effects of the event horizon.

Any atoms that were drawn in by the strength of gravity could just end up in the orbit of the black hole.

Plus, a mini black hole would have evaporated out of existence almost as soon as it was created.

Do Mini Black Holes Exist?

Mini black holes are hypothetical, and we’ve yet to actually discover any.

Black holes themselves are very difficult to spot. They often have to be found using indirect methods and observing interactions in nearby galaxies, as they have no detectable qualities of their own.

On a mini scale, this becomes even more difficult. There’s also still debate about whether mini-black holes would be able to form and, if they could, remain stable.

Primordial Black Holes

The primordial black hole is a type of black hole theorized to have formed shortly after the Big Bang. They’re thought to have been created in the high density of the early universe.

They wouldn’t have required the gravitational collapse of a star to form, unlike conventional models, which means they could have a lower mass. If micro black holes do exist, this is the most widely accepted theory for their creation.

These have yet to be observed, but scientists are currently searching for evidence. The best way to find a primordial black hole would be observing one as it evaporated, releasing an explosion of radiation and a burst of particles.

Any created in the early years of the universe may have already collapsed or be collapsing now, depending on the size and the evaporation rate.

If primordial black holes do exist, they could help explain dark matter.

Final Thoughts

Hypothetically, a mini black hole could be anywhere between a mass of 10 to the power of negative 8 kilograms and just below three stellar masses.

This lower limit is theorized based on the Schwarzschild radius, while the upper limit determines at which point it becomes a standard black hole.

But as mass and density are so important to the existence of any black holes, including creating the gravitational pull that defines the event horizon, the existence of these mini-monsters is still up for debate.

If they are around, they were likely created in the very early universe (and definitely not in the Large Hadron Collider).