If a black hole were to appear between the Earth and an observer, the Earth would appear gravitationally lensed in a fashion similar to this, dependent on the Earth’s position relative to the black hole and the observer. If a black hole were to form from the Earth itself, it would create an event horizon just 1.7 centimeters in diameter. (ANDREW HAMILTON / JILA / UNIVERSITY OF COLORADO)
Yes, we’d all die. But for 21 minutes, we’d have the ride of a lifetime.
One of the most remarkable facts about the Universe is this: in the absence of any other forces or interactions, if you start with any initial configuration of gravitationally bound masses at rest, they will inevitably collapse to form a black hole. A straightforward prediction of Einstein’s equations, it was Roger Penrose’s Nobel-winning work that not only demonstrated that black holes could realistically form in our Universe, but showed us how.
As it turns out, gravity doesn’t need to be the only force: just the dominant one. As the matter collapses, it crosses a critical threshold for the amount of mass within a certain volume, leading to the formation of an event horizon. Eventually, some time later, any object at rest — no matter how far away from the event horizon it initially was — will cross that horizon and encounter the central singularity.
If, somehow, the electromagnetic and quantum forces holding the Earth up against gravitational collapse were turned off, Earth would quickly become a black hole. Here’s what we would experience if that were to happen.[…]
This illustration of spaghettification shows how a human gets stretched and compressed into a spaghetti-like structure as they approach the event horizon of a black hole. Death by these tidal forces would be painful and traumatic, but at least it would also be quick. (NASA / PUBLIC DOMAIN / COSMOCURIO OF WIKIMEDIA COMMONS)