Parallel universes are real, say physicists

The quantum mascot: The paradox of Schrodinger’s Cat is at the heart of the multiverse theory.

Physics professor and TV presenter Brian Cox says he believes we live in just one of an infinite number of parallel universes. Is there any evidence for that and should it change how we think?

In parallel universes, the physics professor Brian Cox is a professional wrestler, a goat herder, a gambler, a mass murderer, and even a rockstar.

It may seem like science fiction, but the existence of multiple Brians and multiples of everyone, in a ‘multiverse’ is a serious concept in physics. This week, Brian Cox said that he supports the theory.

The ‘multiverse’ theory holds that as well as the universe we exist in now, there is an infinite number of others in which all the variations that could have happened in our lives are being played out.

For example, a boy called James thinks about eating a slice of cake. Maybe he stops after one slice and goes to play an average game of football. Or maybe he eats another slice and is too sick to play. Yet in the world where James did not eat any cake at all, he may score an incredible goal which makes him famous. Based on a such a minor decision, James’s life could unfold very differently.

According to the ‘multiverse’ idea, each James theoretically exists in a parallel universe. This thought experiment illustrates a central conundrum in quantum mechanics, which studies the unpredictable behaviour of energy and particles on the smallest scale.

Physicists cannot know where a particle is until they measure it. It might be found at location ‘A’, but some physicists say it is equally likely to be also at ‘B‘. They believe in the act of measuring it we actually determine where the particle is. Once it is seen at ‘A’, humans can only see it as ‘A’, just as once James eats the cake, we can no longer see the alternatives.

Another way of explaining this is with the 'Schrödinger’s cat’ thought experiment. A cat, a flask of poison, and a radioactive source are placed in a sealed box. If an internal monitor detects radioactivity (that is, a single atom decaying), the flask is shattered, releasing the poison. When we open the box, we will see the cat either alive or dead. But, quantum physicists say that, until we do, the cat is both alive and dead, as both possibilities simultaneously exist.

Curiosity killed the cat

Some say that since there is currently no way to prove the ‘multiverse’ theory correct, thinking about it is pointless. While parallel universes might theoretically exist, if we have no way to interact with them and they can have no influence on our lives, then they are of no significance.

Yet others say that though it seems impossible to prove now, that does not mean it will not be possible one day. Besides, it is a fascinating way of thinking about choice and what we might have done differently. It shows just how much cutting edge science can expand our horizons far beyond what we can detect with our senses.

You Decide

  1. Is the ‘multiverse’ theory interesting or a waste of time?
  2. Are today’s scientific theories too obscure for ordinary people to understand?


  1. Share with a partner five decisions you have made today or in the last week and what an alternative you could be doing elsewhere in the multiverse if you had made different choices.
  2. Using the links in ‘Become an Expert’, research the ‘multiverse’ theory and its variants. Make a short verbal or computer presentation on them.

Some People Say...

“Thinking about alternative universes is a waste of time.”

What do you think?

Q & A

How does this affect me?
It doesn’t, directly, but it might be fun to think about how many variations of you there might be in parallel universes. It is also exciting that an idea that seems so odd actually has a sound basis in science.
I still don’t understand how the theory works!
The story here is necessarily a simplification of some very advanced concepts, and physicists do not agree on exactly how the theory would work. Observations in quantum mechanics suggest that the behaviour of particles can never be fully predicted and that many processes we cannot observe are happening on a molecular level all the time. In proposing the existence of parallel universes, scientists are just expanding what happens on the molecular level to the level of everything.

Word Watch

Coincidentally, Cox already has had musical success as the keyboard player in the 1990s pop band D:Ream.
The idea that an atom can be at multiple points at once is called ‘quantum superposition’. The atom appears to move in a wave, but when we measure it, we only see the atom at one point, an idea called ‘wave collapse’.
Some physicists believe at this moment, the other coexisting particles disappear. Yet others say that the wave continues to exist, only we can no longer see it. Schrödinger’s famous cat illustrates the idea that, theoretically, the atom should continue to exist in two places.
Some physicists hope the discovery of ‘gravitational waves’ early this year that possibly go back to the Big Bang might provide evidence of how multiverses work. They hope there will be patterns that link physics on the cosmic scale with the minute scale of quantum mechanics.

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