Doom... but on the bright side, we might not notice for a while!
Have you ever wondered what would happen if a black hole suddenly appeared next to Earth? In short, the planet would be doomed, but let’s dig a little deeper and explain exactly what would take place.
First of all, there are three properties of a black hole that, in principle, can be measured: mass, spin (angular momentum) and overall electric charge. These are the only three things an outside observer could ever know about a black hole since all other information is relatively lost — meaning no matter how complex an object is that gets pulled into the black hole, all that will be left of it is its mass, charge and spin.
However, some physicists have proposed solutions to this Black Hole Information Paradox by proposing that some of this “lost” information can be retrieved through holographic imprints and quantum teleportation.
Now, of these parameters, mass is the most important, because the mass of the black hole — and the gravitational force it generates — is what causes the downfall of nearby objects.
If you get a too close to a black hole, you will begin to stretch out like spaghetti — an effect known as spaghettification — thanks to a gravitational gradient across your body. Imagine you are headed feet first towards a black hole; since your feet are physically closer, they will feel a stronger gravitational pull than your head.
It gets worse. Your arms, since they are not located at the centre of your body, will be pulled in a slightly different direction than your head, meaning the outer parts of your body will be brought inwards. This results in not just an elongation of the body, but also a compressing in the middle… ick!
So, what does this mean for Earth?
The same gravitational effect that produced spaghettification on your body would start to take effect on the planet. The part of Earth closest to the black hole would feel a stronger force than the opposite side, but slowly the planet would be pulled apart and stretched.
On the bright side, depending on the size of the black hole and its event horizon — where the speed required to escape the black hole is equal to the speed of light — everything would appear normal for some time before the doom and gloom began. However, I wouldn’t lose too much sleep over this... it probably won’t ever happen.
Interestingly, if a black hole ever did enter our solar system, some other really bad things would happen. For example, orbits would be thrown off course and planets would inevitably collide into each other! You can watch this short video for a few more details.
Read next: What Would Happen if the Sun Disappeared?