If a coin comes down heads, which means that the possibility of it coming down tails has collapsed. Until that moment the two possibilities were equal. But on another world, it does come down tails. And when that happens, the two worlds split apart. There are many, many, worlds branching out at each moment you become aware of your environment and then make a choice. The idea that multiple versions of the universe could exist comes from the string theory, a mathematical description of the universe that posits that everything is made up of strings too small for us to detect. The vibrations of these strings create the different particles we observe, such as quarks or electrons.
A group of theoretical physicists and network scientists at Northeastern University have found a new way to address this issue by analyzing these possible universes as a network: string theory. String theory only works in a universe with at least 10 dimensions. Now, Network science has been used to study connections in the human brain, and understand how ideas spread through social media and now it is applied to theoretical physics.
According to one Bubble Universe theory, if we picture our own universe as a bubble, it is sitting in a network of bubble universes of space. What’s interesting about this theory is the other universes could have very different laws of physics than our own, since they are not linked. There are five theories on multiverse (a.k.a. parallel universes).
Famously, physicist Stephen Hawking quoted “We are not down to a single, unique universe, but our findings imply a significant reduction of the multiverse to a much smaller range of possible universes”. However, there are many different ways to build a network of potential universes. And the physicists still don’t know which universe within this network is ours, or where it might fall within such a vast network.