[Pierre-Marie Baty]

"how would you get extremely nice physics across a network"

Prediction. Client-side prediction.
The server only tells the clients about the impact parameters. Entities involved, origin, velocity, date, and server's random seed state. If the physics are 100% well-made (i.e, completely FPS-independent), all the clients should end up in the exact same state, no matter their machine or net connection.