We don't even know if the number is finite or infinite. It's certainly a large number because literally every time a tiny quantum mechanical system that is in a superposition becomes entangled with the rest of the world, the world branches into multiple possibilities. These quantum entanglements are quite common events. In a typical human body, a radioactive decay happens about 5,000 times per second. And there's a lot of bodies out there.
The film Everything Everywhere All at Once has enjoyed critical acclaim and awards success. Ahead of the Oscars, where it’s tipped to sweep the board, Ian Sample speaks to theoretical physicist and philosopher Sean Carroll about why we seem to be drawn to the idea of multiple worlds, and what the science says about how the multiverse might actually work. Help support our independent journalism at
theguardian.com/sciencepod