Posted on 04/19/2007 5:36:46 PM PDT by LibWhacker
Quantum mechanics just got even stranger.
There's only one way to describe the experiment performed by physicist Anton Zeilinger and his colleagues: it's unreal, dude.
Measuring the quantum properties of pairs of light particles (photons) pumped out by a laser has convinced Zeilinger that "we have to give up the idea of realism to a far greater extent than most physicists believe today."
By realism, he means the idea that objects have specific features and properties —that a ball is red, that a book contains the works of Shakespeare, or that an electron has a particular spin.
For everyday objects, such realism isn't a problem. But for objects governed by the laws of quantum mechanics, like photons and electrons, it may make no sense to think of them as having well defined characteristics. Instead, what we see may depend on how we look.
This notion has been around ever since the advent of quantum mechanics in the early twentieth century. The theory seemed to show that, in the quantum world, objects are defined only fuzzily, so that all we can do is work out the probability that they have particular characteristics — such as being located in a specific place or having a specific energy.
Allied to this assault on reality was the apparent prediction of what Albert Einstein, one of the chief architects of quantum theory, called 'spooky action at a distance'. Quantum theory suggests that disturbing one particle can instantaneously determine the properties of a particle with which it is 'entangled', no matter how far away it is. This would violate the usual rule of locality: that local behaviour is governed by local events.
Einstein could not believe that the world was really so indeterminate. He supposed that a deeper level of reality had yet to be uncovered — so-called 'hidden variables' that specified an object's properties precisely and in strictly local terms.
Failed test
In the 1960s the Irish physicist John Bell showed how to put locality and realism to the test. He deduced that if both ideas applied to the quantum world, then two particular quantities calculated from measurements made on a pair of entangled photons would be equal to one another. If so, there would be nothing 'spooky' about entanglement after all.
Experiments were done to test his prediction in the ensuing two decades, and results showed that Bell's equality was violated. Thus, either realism or locality, or possibly both of these ideas, do not apply in the quantum world.
But which is it? That's what Zeilinger, based at the University of Vienna in Austria, and his colleagues tried to find out.
They came up with a similar test to Bell's, to see whether quantum mechanics obeys realism but not locality. Again the experiment involves comparing two quantities calculated from measurements on entangled photons, to see if they are equal. But whereas in Bell's test these quantities are derived from the so-called 'linear' polarization of the photons — crudely, whether their electromagnetic fields oscillate in one direction or the other — Zeilinger's experiment looks at a different sort of polarization, called elliptical polarization.
Like Bell's, Zeilinger's equality proved false. This doesn't rule out all possible non-local realistic models, but it does exclude an important subset of them. Specifically, it shows that if you have a group of photons that all have independent polarizations, then you can't ascribe specific polarizations to each. It's rather like saying that you know there are particular numbers of blue, white and silver cars in a car park — but it is meaningless even to imagine saying which ones are which.
Truly weird
If the quantum world is not realistic in this sense, then how does it behave? Zeilinger says that some of the alternative non-realist possibilities are truly weird. For example, it may make no sense to imagine what would happen if we had made a different measurement from the one we chose to make. "We do this all the time in daily life," says Zeilinger — for example, imagining what would have happened if you had tried to cross the road when a truck was coming. If the world around us behaved in the same way as a quantum system, then it would be meaningless even to imagine that alternative situation, because there would be no way of defining what you mean by the road, the truck, or even you.
Another possibility is that in a non-realistic quantum world present actions can affect the past, as though choosing to read a letter or not could determine what it says.
Zeilinger hopes that his work will stimulate others to test such possibilities. "Our paper is not the end of the road," he says. "But we have a little more evidence that the world is really strange."
Interesting.
While Bell is generally applauded for the inequality, it might be that in the long run, the more important part was the proof that there can be no “hidden variable” theory that is compatable with QM. The epistemological implications are impressive and scary at the same time.
If a Pterosaur appeared on your porch, scooped up one of your youngsters and flew away, it looks like that, by itself, would not violate any physical laws.
I knew the world was strange before I read this.
LOL!
It’s a lotta BS. Just because their statistics don’t come out, they conclude that the universe is bazaar beyond belief. They never consider that they might simply be missing a key part of the puzzle which skews all of the results.
Oh please....
It all depends on what the meaning of is is.
And we wouldn’t know what color it was. However the kids shouldn’t have been on the porch.
anyone; any ideas on how this theory might explain ghosts?
However the kids shouldn’t have been on the porch
LOL! That’ll teach them! They weren’t even done with their homework yet!
But on the positive side, they’ll learn a whole lot about Pterosaur biology and habitat!
What about the recent episode on Discovery Science about Supermassive Black Holes? That, was one wow! of an eye-opener. Like, now they can prove a super massive black hole created our universe.
No one can tell fo sho now
Someone is going to have to come up with something new, because this seems to be getting to weird.
Fascinating.
I think I'll go crystalize in a 5 dimension form.
I wondered why my dog morphed into a Klingon before accelerating into that worm hole in the 7th dimension. I guess this doesn’t explain it because nobody is typing this in a quantum mechanical sense.
The problem arises when pseudo-intellectual idiots get hold of something as beautiful and mysterious as quantum mechanics and try to pack humanism on to the back of the sleigh. Because the location of a subatomic particle can not be determined, right and wrong cannot be determined. Because a particle can be in two places at the same time, a person can be sane and insane at the same time. Because the state of a particle depends on the state of the observer, the meaning of "good" and "evil" depend on the cultural background of the person observing and describing these characteristics.
I think that liberalism (or perhaps I should say "humanism") is intensely jealous of the success of science, especially the science of the atomic age, the science of post-WWII western society. I believe that at least some strains of liberalism arose from intellectual poseurs who attempted to transpose the successful concepts of the hard sciences, physics in particular, onto moral philosophy and ethics. Much foolishness was the result and, to the extent that this foolishness has made it out of the effite precincts of academe and into the public square, in the form of laws and institutions, a cataract of pain, suffering, and injustice has been loosed on the world.
Actually, by the where/when you reach the seventh dimension, there are no holes into which you can enter, just branes.
Thanks, that’s hugh! It totally stuned my beeber!
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