How do we know of parallel universes?

[JonnyBoy12]

Sorry if this question has been asked before, but is there any evidence to suggest that parallel universes exist? If so what evidence have we to go on, and how many of them are there? Would it be possible to reach one of them?

[joggerjayne]

It would be just like going to Eastbourne.

[Hymie]

They definitely exist � I recall seeing at least one on Star-Trek.

Another little know fact is that virtually all higher life forms (outside our solar system) use English as their first language.

[BertiWooster]

They have to speak english - can you imagine Star Trek with subtitles ?

[Clanad]

Simple answer is no. The idea was first proposed clear back in 1954 by physicist, Hugh Everett. here in the U.S. His proposal had no scientific support then and has only metaphysical support now.
According to quantum mechanics, nothing at the subatomic scale can really be said to exist until it is observed. It's this act of observation of quantum level objects (not yet seen but mathmatically proposed) that refuse to follow known laws of physics and, somehow, establishes a particular state of reality for the particles shown to exist by theory. Previous to this act of "observation", the particles occupy uncertain states and only come to a "real" state when observed. Scientists don�t yet have a perfect explanation for how it works.

The Large Hadron Collider (LHC) as well as Fermilab�s Tevatron here in the U.S. are attempting to provide answers. We'll wait and see, no?

[jake-the-peg]

There are two seperate notions of paralell Universes. The first that Clanad mentions is retated to ideas in Quantum Mechanics. These ideas (there are other alternatives) are called "interpretations". These are self consistant explanations but can never come up with any actual proof.

CERN will certainly not prove it!

The second rather depends on your idea of what proof entails.

There are certain parameters of our Universe such as the strength of the electric charge or of Gravity that are finely tuned if they were much different there would be no matter, no stars no us.

One suggestion for why this is, is that there are other Universes where these values are different. Of course it could just be that what appears to us to be a huge coincidence is really inevitable. We don't know how these values were set so we can't tell.

Congratulations though you are asking good questions "how do we know xxxxxxx" is one of the best questions anyone can ask.

[R1Geezer]

Most of the parallel universe/multiverse stuff is purely theorised by following the Maths, similarly quantum theory etc as the 2 guys above explain. All we have in physics are theories that get ever stronger by repetition of experiment and the general tendancy to try and debunk them. Hence the theory of gravity is pretty well solid, i Know an apple will fall from a tree, The theory of of parallel universes is allowed by the Maths and no so far proved or disproved that's all we can say really.

[New Judge]

Of course a parallel universe exists!

Its principle inhabitants are some 650-odd souls who spend most of their working hours (which are not very many) roaming around a vast palace adjacent to the River Thames in London. More lowly in the pecking order in this second universe are myriads of Quangocrats, and local councillors spread elsewhere throughout the land.

For them the normal rules which apply to us lesser mortals are of no concern as they go about their business of imposing agendas which few people want and even less voted for.

For this they are rewarded handsomely, unencumbered by many of the tax and revenue regulations which trouble �ordinary� people.

[jake-the-peg]

Really I thought the parallel Universe was entirely populated by a buch of predominantly white middle classed men wandering around in wigs and stockings pronouncing judgement on people who's lives and background they have thave little appreciation of before retiring to drink themselves soppy on sherry and port.

[beso]

I doubt they are parallel. More likely to be skew.

[Tom Braider]

The idea that there are parallel universes is usually taken to arise from quantum theory, in which contexts it is referred to as the many worlds interpetation. The thinking behind this gets heavy - see here http://en.wikipedia.org/wiki/Many-worlds_inter pretation - but in David Deutsche's book "The Fabric of Reality" there's a very clear argument that the behaviour of light and shade implies the existence of parallel universes. That book will blow your mind! There are an infinite number of PUs (if there are any). We travel amongst them all the time - but not, unfortunately, at will.

[Tom Braider]

By the way, Hugh Everett's son is the leader of US rock band The Eels. They're pretty good, too!