The multiverse is a set of theoretically infinite or limited possible universes, including everything that exists and may exist: all space, time, matter, energy and the physical laws and constants that describe them. The universes contained in the multiverse are called parallel universes.

In 1950s, when some physicists observed quantum, they found that each quantum state was different. Because all matter in space is made up of quanta.

So these scientists speculate that because each quantum has a different state, it is possible that there is not just one universe, but several similar universes. The concept of parallel universe benefits from the scientific discovery of modern quantum mechanics.

Extended data:

First, put forward the background.

The concept of parallel universe is not put forward because of the paradox of time travel, but comes from quantum mechanics, because quantum mechanics has an uncertainty, that is, quantum uncertainty. The concept of parallel universe benefits from the scientific discovery of modern quantum mechanics.

In 1950s, when some physicists observed quantum, they found that each quantum state was different. Since all matter in the universe is made up of quanta, these scientists speculate that the universe may be made up of many similar universes, not just one, because each quantum has a different state.

Second, formally put forward

Physicist Everett put forward his own idea about quantum measurement. He pointed out that in quantum mechanics, there are many parallel worlds, and in each world, the results of each quantum mechanical measurement are different, so different histories will appear in different parallel universes. The multi-world explanation holds that the observation of the measuring device will decompose the measuring device into two.

This decomposition will continue in this measurement chain. With this decomposition, there must be a complete copy of the universe. That is to say, as long as there is a quantum measurement, every branch of the universe and the components in this branch will lead to a possible measurement result.

Everyone in a special branch of the universe will think that his measurement results are unique to his universe. In other words, a measurement produced a new universe. These different new universes can never overlap unless they are exactly the same. The publication of this theory marks the formal proposal of the concept of parallel universe.

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