Do Parallel Universes exist ?

These findings suggested that there are other laws at work in the universe, operating on a deeper level than the one we know.

"The Chronicles of Narnia" (1950-56), a C.S. Lewis book series, features several children who move between our world and the world of Narnia, where there are talking animals. Some of these books were released as feature films earlier in the 2000s.

An episode of "Star Trek" featured a "mirror universe" in which the characters were more ruthless and warlike. The concept was repeated in nearly every subsequent "Star Trek" series. In 2009, the "Star Trek" universe got a reboot in a movie that put the characters from the 1960s original series in an alternate universe. The movie starred Chris Pine and Zachary Quinto and set off a series of other "Star Trek" films.

In fairly short order, physicists studying the quantum level noticed some peculiar things about this tiny world. For one, the particles that exist on this level have a way of taking different forms arbitrarily.

In "The Dark Tower," a Stephen King series that began in 1982, travellers go through portals to different levels of the titular tower (in other words, parallel Earths). Part of the series was adapted into a feature film in 2017.

For example, scientists have observed photons -- tiny packets of light -- acting as particles and waves.

The "Back to the Future" movie series (which began in 1985) follows the adventures of the McFly family, including visits to 1885, 1955 and 2015.

Even a single photon exhibits this shape-shifting [source: Brown University.

"Run Lola Run" (1998) is a film starring Franka Potente. The film shows multiple alternatives as a woman tries to get 100,000 Deutsche marks in only 20 minutes to save her boyfriend's life.

Imagine if you looked and acted like a solid human being when a friend glanced at you, but when he looked back again, you'd taken a gaseous form.

"Timeline" (1999) by Michael Crichton follows historians who go back in time to the Middle Ages. (While the book is mostly a time travel book, the multiverse is used in it as well.) A film based on the book was released in 2003.

This has come to be known as the Heisenberg Uncertainty Principle. The physicist Werner Heisenberg suggested that just by observing quantum matter, we affect the behavior of that matter.

"The Long Earth" book series, by Terry Pratchett and Stephen Baxter, discusses parallel universes that may be nearly the same as Earth.

Thus, we can never be fully certain of the nature of a quantum object or its attributes, like velocity and location.

This idea is supported by the Copenhagen interpretation of quantum mechanics. Posed by the Danish physicist Niels Bohr, this interpretation says that all quantum particles don't exist in one state or the other, but in all of its possible states at once.

The sum total of possible states of a quantum object is called its wave function. The state of an object existing in all of its possible states at once is called its superposition.

According to Bohr, when we observe a quantum object, we affect its behavior. Observation breaks an object's superposition and essentially forces the object to choose one state from its wave function.

This theory accounts for why physicists have taken opposite measurements from the same quantum object: The object "chose" different states during different measurements.

Bohr's interpretation was widely accepted, and still is by much of the quantum community. But lately, Everett's Many-Worlds theory has been getting some serious attention. Read the next page to find out how the Many-Worlds interpretation works.