Nib asked, and Nib — askNib's tutor — drew the answer live at a whiteboard. This is the spoken transcript; enable JavaScript to watch it drawn.
What is a black hole, and what would happen if you fell in? (for a curious adult who has not studied physics). Cover, in this order: What is a black hole?; How can gravity be strong enough to trap light?; How does a black hole form?; What is the event horizon?; What happens if you fall into a black hole?; If nothing escapes, how do we see black holes?; Do black holes really suck everything in?; Can a black hole die? — page 5: Falling into a black hole
Far from the black hole, a falling person feels no wind and no pull. Falling freely feels just like floating.
Now you cross the event horizon. No wall, no flash. You pass through unaware that you have crossed the point of no return.
Inside, every path points inward. To climb back out you'd need to beat light. Nothing can. Struggle all you like; the center is coming.
Here's the danger: gravity is stronger closer in. Your feet get pulled harder than your head. That difference stretches you out, like pulling taffy.
Gravity is stronger closer in, so your feet are pulled harder than your head. That difference stretches your body out, like pulling taffy.
Your body is stretched thin, like taffy. The black hole's pull is the same; only the difference between your head and feet stretches you.
Size matters. A small black hole shreds you before the horizon. A giant, millions of Suns, lets you cross gently, and tears you apart deeper in.
So falling in is quiet at the threshold and brutal at the end: you cross a line you cannot feel, then cannot return, then are stretched apart.