Parallel Universe Proof Boosts Time Travel Hopes

[Squaggles]

From www.telegraph.co.uk :

Science fiction looks closer to becoming science fact, reports Roger Highfield

Parallel universes really do exist, according to a mathematical discovery by Oxford scientists that sweeps away one of the key objections to the mind boggling and controversial idea.

The work has wider implications since the idea of parallel universes sidesteps one of the key problems with time travel. Every since it was given serious lab cred in 1949 by the great logician Kurt Godel, many eminent physicists have argued against time travel because it undermines ideas of cause and effect to create paradoxes: a time traveller could go back to kill his grandfather so that he is never born in the first place.

But the existence of parallel worlds offers a way around these troublesome paradoxes, according to David Deutsch of Oxford University, a highly respected proponent of quantum theory, the deeply mathematical, successful and baffling theory of the atomic world.

He argues that time travel shifts between different branches of reality, basing his claim on parallel universes, the so-called "many-worlds" formulation of quantum theory.

The new work bolsters his claim that quantum theory does not forbid time travel. "It does sidestep it. You go into another universe," he said yesterday, though he admits that there is still a way to go to find schemes to manipulate space and time in a way that makes time hops possible.

"Many sci fi authors suggested time travel paradoxes would be solved by parallel universes but in my work, that conclusion is deduced from quantum theory itself", Dr Deutsch said, referring to his work on many worlds.

The mathematical idea of parallel worlds was first glimpsed by the great quantum pioneer, Erwin Schrodinger, but actually published in 1957 by Hugh Everett III, when wrestling with the problem of what actually happens when an observation is made of something of interest - such as an electron or an atom - with the intention of measuring its position or its speed.

In the traditional brand of quantum mechanics, a mathematical object called a wave function, which contains all possible outcomes of a measurement experiment, "collapses" to give a single real outcome.

Everett came up with a more audacious interpretation: the universe is constantly and infinitely splitting, so that no collapse takes place. Every possible outcome of an experimental measurement occurs, each one in a parallel universe.

If one accepts Everett's interpretation, our universe is embedded in an infinitely larger and more complex structure called the multiverse, which as a good approximation can be regarded as an ever-multiplying mass of parallel universes.

Every time there is an event at the quantum level - a radioactive atom decaying, for example, or a particle of light impinging on your retina - the universe is supposed to "split" into different universes.

A motorist who has a near miss, for instance, might feel relieved at his lucky escape. But in a parallel universe, another version of the same driver will have been killed. Yet another universe will see the motorist recover after treatment in hospital. The number of alternative scenarios is endless.

In this way, the "many worlds" interpretation of quantum mechanics allows a time traveller to alter the past without producing problems such as the notorious grandfather paradox.

But the "many worlds" idea has been attacked, with one theoretician joking that it is "cheap on assumptions but expensive on universes" and others that it is "repugnant to common sense."

Now new research confirms Prof Deutsch's ideas and suggests that Dr Everett, who was a Phd student at Princeton University when he came up with the theory, was on the right track.

Commenting in New Scientist magazine, Prof Andy Albrecht, a physicist at the University of California, Davis, said of the link between probability and many worlds: "This work will go down as one of the most important developments in the history of science."

Quantum mechanics describes the strange things that happen in the subatomic world - such as the way photons and electrons behave both as particles and waves. By one interpretation, nothing at the subatomic scale can really be said to exist until it is observed.

Until then, particles occupy nebulous "superposition" states, in which they can have simultaneous "up" and "down" spins, or appear to be in different places at the same time.

According to quantum mechanics, unobserved particles are described by "wave functions" representing a set of multiple "probable" states. When an observer makes a measurement, the particle then settles down into one of these multiple options.

But the many worlds idea offers an alternative view. Dr Deutsch showed mathematically that the bush-like branching structure created by the universe splitting into parallel versions of itself can explain the probabilistic nature of quantum outcomes. This work was attacked but it has now had rigorous confirmation by David Wallace and Simon Saunders, also at Oxford.

Dr Saunders, who presented the work with Wallace at the Many Worlds at 50 conference at the Perimeter Institute for Theoretical Physics in Waterloo, Canada, told New Scientist: "We've cleared up the obscurities and come up with a pretty clear verdict that Everett works. It's a dramatic turnaround and it means that people now have to discuss Everett seriously."

Dr Deutsch added that the work addresses a three-century-old problem with the idea of probability itself, described by one philosopher, Prof David Papineau, as a scandal. "We didn't really know what probability means," said Dr Deutsch.

There's a convention that it's rational to treat it for most purposes as if we knew it was going to happen even though we actually know it need not. But this does not capture the reality, not least the 0.1 per cent chance something will not happen.

"So," said Dr Deutsch, "the problems of probability, which were until recently considered the principal objection to the otherwise extremely elegant theory of Everett (which removes every element of mysticism and double-talk that have crept into quantum theory over the decades) have now turned into its principal selling point."

[Father McPot]

Strange, I was reading about that not long ago in one of RAW's books.

Quite like this idea.

[HvyFuel]

Is the conspiracies section full?

[Father McPot]

What you mean, Hvy?

edit to say: Don't like that title at all. There isn't any "proof" at all, it's still just a theory, from what this acticle shows anyway.

Edited September 26, 2007 by Father McPot

[HvyFuel]

Parallel universes!? Little green men. Leprechauns. Fairies.

[Squaggles]

Is this the wrong section to post it in ?

I thought it was quite interesting myself . If you know the story of John Titor the self-proclaimed time traveller then I believe this is how he explained time travel and the fact that he couldn't exactly predict the future .

Is the conspiracies section full?

[Hipgnosis]

Parallel universes!? Little green men. Leprechauns. Fairies.

God.

Google video.. BBC Horizon: Parallel Universes

[Twenty Three]

Parallel universes!? Little green men. Leprechauns. Fairies.

Did you actually read the original post in this topic Hvy ?

Great link Hipgnosis

[Guest Rex Mundi]

The new work bolsters his claim that quantum theory does not forbid time travel. "It does sidestep it. You go into another universe," he said yesterday, though he admits that there is still a way to go to find schemes to manipulate space and time in a way that makes time hops possible.

"Many sci fi authors suggested time travel paradoxes would be solved by parallel universes but in my work, that conclusion is deduced from quantum theory itself", Dr Deutsch said, referring to his work on many worlds.

This is not really time travel is it?

Time travel is to travel backwards in your own time-dimension, and what is described here is interdimensional travel, and what time period you pop up in this other dimension is nothing to do with your own time, if it ain't your universe, it ain't your time.

[tsk]

Is this the wrong section to post it in ?

I thought it was quite interesting myself . If you know the story of John Titor the self-proclaimed time traveller then I believe this is how he explained time travel and the fact that he couldn't exactly predict the future .

yeh, titor did say the "many world" theorys was the correct one. he also said there was no olympics in china gonna happen, or words to that effect. trouble in burma eh... ?

hugh everret, the dude who came up with The Theory of the Universal Wave Function (many worlds) left physics a few years after defending his thesis as so few others in the same field took him seriously. so he went and worked fopr the government as an advisor, became a succseful billionaire and donated spunk to making the lead singer of the Eels.

Parallel universes!? Little green men. Leprechauns. Fairies.

no offence mate, but do one

This is not really time travel is it?

no, its a newspaper article

[HvyFuel]

Theory, conjecture, bibble babble. Show it working in practice and I'll accept it.

"repugnant to common sense."

Sounds about right.

And I'll post anywhere I feel like tsk.

[tsk]

Theory, conjecture, bibble babble. Show it working in practice and I'll accept it.

And I'll post anywhere I feel like tsk.

never said you couldnt dude, just using the only manchester slang i know without swears snot like i would tell anyone where they could or couldnt post. not my bag

the differance, i think, between Little green men, Leprechauns and Fairies - and something like The Theory of the Universal Wave Function, is the latter is an interpretation of quantum mechanics originally proposed by an individual who later developed the use of Lagrange multipliers in operations research as a defense analyst for considerable financial gain. he wasnt poorly equiped in the brain cell department is my point.

little green men, leprechauns and fairies were not, as far as i know, the subject of a princeton phd, nor are they part of the collective "multiverse hypothesis" pondered by physics and philosophy. so its a pretty poor comparisson, imo.

im prepared to live with the idea that there are other universes out there and all versions of this reply have been posted

big love to this and all the other universes ...

[Father McPot]

Gravity?

[Arnold Layne]

I read a load of essays by scientists a few years back. Some of whom were talking about multi-decker universes etc; so I think its something one has to take with a little gravitas Hvy. The collection was published - "The Universe Next Door", I think under the Editorial hand of Marcus Chown.

This is not really time travel is it?

Time travel is to travel backwards in your own time-dimension, and what is described here is interdimensional travel, and what time period you pop up in this other dimension is nothing to do with your own time, if it ain't your universe, it ain't your time.

You know, I just came to this thread to say just that. Ya bugger, you beat me to it!

Popping up in another dimension could be well scary if you ask me - this one is odd enough

[HvyFuel]

Gravity?

Jump off a highrise building and tell me you can't see gravity.

I theorise that if I travel faster than light I'll be able to see the fairies at the bottom of my garden, but as we can't travel faster than light it remains a theory. Whether Steven Hawkins or the spotty teen serving your McDonalds says it, it's still a theory.

Edited September 29, 2007 by HvyFuel