Zachary has many grievances against me. (Actually, many people have grievances against me; they just don't reduce them to blog comments.) For example, this week, in his own blog, he hurls my way the familiar accusation that, like Obama himself, I'm a wishy-washy liberal, ready to compromise away my values until nothing is left worth fighting for.
Hogwash, of course. But he does have a right to complain about an exchange of comments recently, on this blog, in which I scorned his concept of instantaneous teleportation, archly reminding him of a basic tenet of relativity theory -- no information can be transmitted faster than the speed of light. I scorned him, knowing as I did so that I wasn't being totally candid.
The "problem" is quantum mechanics. A number of thought experiments can be devised -- none of which, unfortunately, I can remember well enough to describe for your amusement -- that involve the interacting quantum states of elementary particles. These "experiments" illustrate the logical and necessary consequences of certain well-accepted concepts of quantum theory. They lead to bizarre results, results that make no sense whatsoever in terms of every day life. Specifically, they show that two elementary particles -- totally insulated from each other and at any distance of separation -- appear to "know" and react to each other's quantum state. In some of these illustrations, when we change the state of one particle, the other particle seems to change instantaneously in response.
Information has apparently been communicated instantaneously between the two particles, regardless of their distance from each other.
Einstein, whose theory of relativity I threw in Zachary's face, appreciated that quantum theory would lead to this conclusion. He didn't like it. He criticized the theory of quantum mechanics, and its implication that reality (at the subatomic level) bears less resemblance to Newtonian physics than to statistics, by writing in 1942:
It seems hard to sneak a look at God's cards. But that He plays dice and uses 'telepathic' methods... is something that I cannot believe for a single moment.
Physicists now say we have to choose between believing that the change in one particle "causes" the change in another particle, on the one hand, or -- on the other hand -- rejecting such causation but also rejecting the objective reality of the universe, at least at the subatomic level where quantum effects can be seen. If we choose the latter option, we are forced to accept the conclusion that "reality" constantly changes depending on what we are observing.
My reading today of a report of an experiment in "teleportation" leads me to write the above apology. The report describes an actual physical experiment involving two ytterbium ions that were totally separated and contained in isolated vacuum chambers. Although the mechanics of the experiment, as described in the report, sound somewhat confusing -- at least to me -- essentially the experimenters aimed a laser burst at one ion, giving it a known quantum state. They were then able to read the quantum state of the other ion, determining that it had also changed its state in a complementary manner, apparently in response. Thus "information" had somehow been transmitted instantaneously from one ion to the other, despite the fact that they were totally isolated from each other.
The article concludes with a "Beam me up, Scotty" section, discussing whether these quantum effects could someday make human teleportation feasible. I leave that subject to the perusal of Zachary's mad scientists in his Benign Colorado Dictatorship.
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Author's note (1-24-09):
Euclid's geometry is a theoretical geometry about a theoretical space that does not in fact exist. And Newton's physics is a theoretical physics about a theoretical world that does not in fact exist. So we have had to change all that with relativity and quantum mechanics.
--John Dobson
The thought experiment that I could not "remember well enough to describe" is the "double slit experiment," said to be described in the last chapter of Richard Feynman's Six Easy Pieces, although I haven't read that book. I believe I encountered discussion of the experiment in Feynman's Lectures on Physics, which is an outstanding collection of lectures prepared originally for Caltech's first-year physics students and later published.
4 comments:
There are a few things about quantum physicists that makes me wish they would just shut the hell up. Quantum entanglement is one of them.
So two atoms changed their quantum state at the same time? This proves nothing. Such things are always in flux, and there's no reason to believe that the two events were related in any way. If it rains in Tokyo and London at the same time, we don't say one is responding to the other.
Other quantum physics topics that piss me off: Schrödinger's cat (What people tend to forget about this particular thought experiment that is now used to explain the effect of the observer on reality is that the man it is named after talked about it as a way of showing how absurd the notion is.); string theory (Subatomic particles act like vibrating strings? That's the best you could come up with? Really?); extra dimensions (There's no way we could ever possibly conceive what they'd be like. Ever. Besides, anything beyond 3 dimensions really has no practical effect on us.).
Be patient. Be curious. Be open-minded, realizing that we see one tiny area of the universe with senses that detect only what they learned to detect from our needs as savages.
Be humble.
Don't scoff at Nobel prize winners when you're a freshman. :-)
The result of the physical experiment I read about (the ytterbium ions) may be explained away, although reputable scientists don't usually present results without cautioning about possible alternative explanations. But quantum theory itself -- an understanding of which makes possible much of modern technology -- results in the weirdnesses and contradictions that Einstein disliked, and logically predicts results like found in the ytterbium ion experiment.
"No practical effect" is merely an engineer's concern.
But thanks for the worthwhile comment. My post wasn't clearly written enough that many readers would even follow what I was saying.
I'm not saying all quantum physics is pointless or flawed; most of it makes sense. But there are just a few areas within quantum physics, like this one and the others I mentioned, that I find quite absurd.
Quantum mechanics describes nature as absurd and it fully agrees from the point of common sense. And it fully agrees with experiment. So I hope you can accept nature as She is - absurd.
- Richard Feynman (Caltech professor, winner of 1965 Nobel prize for work in quantum electrodynamics, and author of some of the most entertaining lectures in physics ever prepared)
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