Time travellers: David Tennant as Doctor Who
with Billie Piper as Rose
Posted on 09/22/2007 8:52:50 PM PDT by bruinbirdman
Science fiction looks closer to becoming science fact.
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.
Time travellers: David Tennant as Doctor Who
with Billie Piper as Rose
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 Papineu, 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."
So was Einstein wrong, and God really does roll the dice, or am I just interpreting this statement incorrectly ?
I have always assumed that the predictions of quantum mechanics based on probability, were really due to the disappearance and reappearance of particles from parallel universes. When we measured a particle 'cloud', the particle appears from a parallel universe. It just makes sense.
And the recent predictions from M-theory also make sense, removing the singularity of the big bang and confirming the existence of a combined theory of gravity and quantum mechanics that Einstein pursued in the final decades of his life.
BUMP
Occasionally your car keys spend a little time there, too
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I must admit, it would clear up a few mysteries for me!
And if a tree falls in the forest, it makes a sound AND it doesn’t
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Define sound. I have always considered sound to mean what we hear, in that case there is no sound unless some being is there to hear it. In the absence of a listener there would be vibrations but no sound. If the only listener is someone who is stone deaf there would still be no sound. Some seem to define sound to mean the vibrations themselves but that doesn’t seem right to me.
I can sit in silence and hear the opening notes of a Beethoven symphony just as I can sit in the dark and see the sun set over a mountain. Sounds and visions exist only in the mind, the stimulus which we interpret as sound and vision may be considered to have external reality but not the sounds and the visions themselves.
where Hillary Clinton is the dog catcher for Westchester County.
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I would prefer the one where she is a slave picking cotton on a Mississippi plantation. All kinds of possibilities open up from there, just let your mind be free!
Explains how God can be everywhere at the same time.
*Yes. It’s call the EVIL parallel universe.*
Exactly, and we get to wear goatees like Spock did in “Mirror, Mirror.”
Do my TV remotes go there too? If so, how come I don’t find the remotes from the other guy in the parallel universe?
What the article says (I think) is that it's a mathematical certainty that in some parallel universe you won the election.
I just looked. How did you do that? You came to my house and attached the key to the cord! The mind is a wonderful powerful thing. Don’t send a bill, I’ll just leave milk and cookies the next time. :>)
No. It's interesting and possibly internally coherent. Time travel is possible but hasn't been done anywhere ever even though it might be being done right now.
In that case, what happened to Richie Valens and the Big Bopper?
The topic has gone past my understanding.
I’m also wary of drifting into metaphysics. I’m OK with philosophy, but I don’t think that it overlaps with science except in mathematical interpretations... which the philosophers always conveniently ignore.
In Music Theory 101 we spent one of the first classes in the semester doing that. The agreement was more or less total. We would define sound as what happens at the instant and after when the sonic energy reaches a musician's ear.
Perhaps Steve Fossett has discovered how to get there.
You never have sensed an event in the present of the actual occurrence, yet your mind manufactures a scenario of 'present' based upon faithe in the constancy of spacetime phenomena rooted in the receiving of past events processed after the fact. Your very living is a time travel process, my brainy friend.
I don't do paradigms since I found out Jesus didn't approve of sacrifice. Time, though, I know from physics, and I also know from philosophy. Two different animals.
Everyone on this thread thinks it’s big news that there is a multiverse out there.
They obviously haven’t checked out their dryer vents. Dryer vents are actually wormholes that lead directly to a multiverse populated with socks (but only one of each color and type.)
They’re trying to sort socks. (See post 99.)
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