The first ten seconds
The page loads looking completely normal, then the logo drops out of the header like someone cut a wire. Everything else follows within a second or two. The search box lands on its edge and tips over. Result blocks pile up along the bottom and slide off each other until they find somewhere to sit.
You can keep typing in the search field after it has landed sideways. That is the detail that makes people call other people over.
Throwing things
Grab any block, swing it, let go mid-arc. It keeps whatever speed you gave it. Blocks collide with each other here rather than passing through, so a hard throw into the pile scatters the lot.
Turn on bouncy google and nothing settles. The whole stack keeps twitching, corners knocking against corners. It is the closest this gets to being annoying, and it is also the setting most people leave switched on.
Where it came from
A developer wired a physics engine to a copy of the search page around 2009, mostly to show that a browser could do it. Everyone knows where the pieces of that layout belong, so seeing them in a heap reads instantly, and the demo travelled further than the technique it was demonstrating.
Every variation since is the same code with the force pointed somewhere else. Aim it at a moving point and you get the google gravity black hole. Reverse it and the page rises, which is floating google. Add buoyancy and you are looking at google underwater, the one people call google gravity water.
Things people ask
Did I break something?
No. Refresh and it is a normal page again. Nothing is saved anywhere.
What is a google gravity roll?
Spin first, collapse second. Run do a barrel roll, wait for it to land, then let gravity take it.
Does it work on a phone?
Yes, and dragging with a finger throws harder than a mouse does, which is worth knowing before you fling the logo into a corner.