Can multiple scenes run at the same time?

I’m trying to get a deeper understanding of what a scene is and how to best make use of scenes.

Can multiple scenes be loaded and running at the same time?
This means all game objects in each of the scenes gets updated while the game is running.

Can the focus (camera object) be swapped between the active screens?
How do I code to switch focus between multiple running scenes.


One way to solve this is to locate everything in the main scene. Leave gaps between areas, essentially making them unreachable. Then switch camera with the remote areas.