What Would We Experience If Earth Spontaneously Turned Into A Black Hole?

Let’s say the Earth turned into a black hole. What would happen to someone standing on the surface and for how long would it happen? From Ethan Siegel:

As spectacular as falling into a black hole would actually be, if Earth spontaneously became one, you’d never get to experience it for yourself. You’d get to live for about another 21 minutes in an incredibly odd state: free-falling, while the air around you free-fell at exactly the same rate. As time went on, you’d feel the atmosphere thicken and the air pressure increase as everything around the world accelerated towards the center, while objects that weren’t attached to the ground would appear approach you from all directions.

• black holes
• Ethan Siegel
• physics
• science