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."
"...Form is empty, emptiness is form.
Emptiness is not other than form.
Form is not other than emptiness. ..."Prajnaparamita (the perfection of wisdom)
The Heart Sutra of Buddha Shakyamuni
There are no parallel universes. There is only one universe.
“time travel” is impossible.
Interesting, if Scary. Scary because it makes perfect sense to me.
This begs the question: “Why is the run gone?” Just kidding, in this universe anyway...
I grok him too.
Try telling that to a Darwinist on a crevo thread.
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I think it would be the creationists who are more likely to DISAGREE with that post rather than the “Darwinist”, I presume that by Darwinist you mean someone who believes evolution is a more valid theory than creationism.
Mathematical formulation of quantum mechanics
Facts are what we see. Theories are our explanation for the facts. Even when the explanation is backed up by trillions of pieces of fact, and is basically irrefutable (such as the theory of evolution), it still remains a theory, because that’s what it is, a theory, an explanation.
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Try explaining that to a bunch of die-hard creationists, you will probably travel through a lot of time before you ever make one understand what you are saying.
Discussing it while ignoring these equations is pointless, wrong, and self-deluding.
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I can only assume you are correct, the equations are unknown to me, that is why I don’t discuss quantum theory. The definition of just what sound is appears to me to lie totally outside of quantum theory. As for the existence of parallel universes, I leave that speculation to others.
klatu verata nictu!
There’s no point in doing that, in my opinion. Just a clear statement of what I think and then an agree-to-disagree. The purpose of this website isn’t to get all didactic in the sciences. People think what they think on these subjects. That’s fine. What’s much more important, in my opinion, here on FR, is to stay connected on as many Conservative Principles as we all can. Look for as many points of agreement as we can.
We all have a big battle coming up in ‘08. An apocalyptic battle. I don’t care if the soldier at my side disagrees with me on some question of science.
We all have a big battle coming up in ‘08. An apocalyptic battle.
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Just when my frazzled nerves start to unwind you have to go and remind me of that. I can’t think about it all the time without going mad.
I know. If we lose, we’re going to look back on the final Lame Duck years of the Bush presidency as the Halcyon days.
Last night I was reading a CREVO thread. The contrast with this one is striking.
That’s because too many on both sides of the CREVO argument are more concerned about being “right” than in truth and honest, respectful debate.
I still get pings and read the articles. I stopped reading the comments.
Umm... Can somebody point me toward the parallel universe where Bill Clinton was shot by a jealous husband and Ted Kennedy didn’t make it out of the submerged car. I want to live in that one.
yitbos
Thanks Las Vegas Dave. I think I want to travel forward to the time when I get to do the dirty with Billie Piper.
And perhaps in another one Bill Clinton was never elected and Hillary is in prison. Which, come to think of it, would be my kind of universe ...
Its still not time travel because you are not going backward or forward in time, just hopping over to other streams.
Gort protect us.
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