Slashdot Mirror
Quantum Trickery - Einstein's Strangest Theory
breckinshire writes "The New York Times is running an interesting story on Einstein's strangest theory. The theory was brought to light this past fall when 'scientists announced that they had put a half dozen beryllium atoms into a "cat state." [...] These atoms were each spinning clockwise and counterclockwise at the same time.' It is an interesting writeup for even the uninitiated and also concentrates on Einsteins role as a 'founder and critic of quantum theory.'"
As Richard Feynman pointed out, "why" is a question of philosophy, not science. The question why has no end. Why do electrons repel each other? That no one knows, they just do. I might go so far as to say it can't be known. Most people stop asking why when they get an answer they're familiar with. Science deals with questions of how. How do electrons repel each other? Well, current theory says that photons travel from one electron to another and push them apart.
AccountKiller
Anytime quantum mechanics is brought up among a non-science crowd (sorry, desipte the geekyness of slashdot, the moderation and general comments I see indicate it's a non-science crowd) you wind up getting half-truth mystical garbage like this and this. The more hard to understand it is, the more people will come up with their own, wrong interpretations.
AccountKiller
Not quite. That would be what's called a hidden variables system: the unit still does have a real location, which is tracked by the program, even if it's inaccessible to an observer within the system. However, that doesn't appear to be the way our universe works; the Bell inequalities show that hidden variables are incompatible with locality.
Real Daleks don't climb stairs - they level the building.
"I've been curious what is the justification for support of: particles are in multiple simultaneous states until measured causing the distributed probabilities to collapse into a definite known state"
The famous double-slit experiment demonstrates the problem very well. Imagine shooting electrons through a wall with two slits. The slits are close enough that each electron, given the vagueness of its exact position, could go through either slit. After going through the slits, the electrons register themselves on a detection screen of some kind.
Well, if you have a sensor at each slit watching to see where the electrons go, they each go through either one slit or the other quite nicely, and they register their impacts on the screen in a nice bell distribution.
However, if you don't check which slit the electrons go through, there is equal possibility of going through both. Therefore, bizarrely enough, they actually *do* go through both slits at once. The detector then records a more complicated ripple pattern of impacts, as each electron's ghostly half interferes with the other half in a wave pattern.
So when we say there are two opposite states existing at once in the quantum world, it is actually true, and the effect is often bizarre. But the state of a particle behaves itself when you decide to "look" at it.
"Alternately, if schroedinger's cat is in an alive/dead superposition in the box, then if the cat experiences a sane and straightforward set of experiences yet the outside-of-box observer claims it to be in an alive/dead combo state, then outside the box observer and inside the box observer's consciousness lines must potentially deviate."
Schödinger introduced the cat just to point out this weirdness. What does the cat see? Is he both alive and dead at once? Does the universe split into two timelines? Adherents of the "Copenhagen Interpretation" would, I think, argue over whether or not the cat qualifies as an observer, and can collapse the quantum randomness on his own.
Another, more intriguing interpretation, is that at last, when you look at the cat and see whether he died or not, your observation propagates a randomness-collapsing wave *backwards in time* that forces the past action of the cat living/dying to resolve itself. There are variations of the double-slit experiment (like measuring the slits after the electron's already through) that reinforce this idea.
Note that I'm not a physicist, and not necessarily good at explaining things.
He who lights his taper at mine, receives light without darkening me.
There are, broadly speaking, two types of scientist - theorists and experimentalists.
Theorists focus on the "why" (to some extent, but really more of a "how") - "Why don't we see starlight in every portion of the sky?" leads to a question of "What are the possible scenarios in which we would see the sky as we see it?" leads to theories - "We see the night sky the way it is because [...]"
Experimentalists then enter the picture. "Well, if [...] was the reason for the sky looking as it does, then we should find X and Y traits also." Then they do their experiments and record the observations. Sometimes, those observations match up with the theoretical predictions. Sometimes, those observations are almost, but not quite right, and sometimes they're incredibly far off, and everyone needs to go back and look for sources of difference.
Now, you dismiss experimentalists as being just "applied mathematicians" (or, at least, that is certainly what your tone implies - they're somehow less relevant, valuable, whatever than "pure" mathematicians) - however, one cannot be terribly effective without the other.
Some scientists are exceptional at both theory and experiment - Issac Newton would be an excellent example of that fusion. Some are pure theorists - Einstein is a poster child for those folks. And some are pure experimentalists - Hubble would be my pick as an archetypical experimentalist.
Since I can't tell them apart, I treat all ACs as the same person.
Quite easy. A. Einstein took the Quantum Theory and tried to get very, very strange predictions from it. Basicly he did what Science is about: To test the theory, he used it to predict the outcome of certain experiments.
Most of the predictions appeared completely absurd to him, and he wrote papers about those (like the Bose-Einstein-Condensate or the synchronous state as mentioned in the article). Because of the counterintuitive results he was getting from applying Quantum Theory he doubted its validity.
But most of the described experiments weren't feasible at the time they were thought out. Some of them are right now, and the Bose-Einstein-Condensate is a reality, and this article in the NYT describes another one of the strange predictions being proved.
So with doubting the predictions of Quantum Theory and describing experiments to falsify them A. Einstein in fact lead the way to the advancement of the same theory he had his problems with. That's a fine example of how Science is supposed to work: Always try to find contradictions to the theories and describe experiments which might falsify the theory. Advancement of Science doesn't care if you believe the theories to be correct. Every new hypothesis has its bugs and rough edges which can only be corrected if someone actually finds experiments where the bugs show up.
Sorry man, but you're just wrong. If this was actually just an incompleteness of information, then the classic double slit experiment wouldn't work. When the experiment is done emitting just one photon at a time, if the particle always has a specific location and speed in time then the experiment would break and you wouldn't get the interference pattern, you'd just get two bands of light on the target. However, since the position of the photon actually is indeterminist until measurement, it interferes with itself, thus creating the interference pattern, even though only one photon at a time is being emitted.
It has withstood rigorous experimentation. Just because you do not understand Quantum Mechanics (very few people, if that, would claim to understand Quantum Mechanics) doesn't make it false.
A hammer and 20 minutes later it'll be fixed.
I'd say by about 50.
Real Daleks don't climb stairs - they level the building.
where are all the gadflies who normally come out of the woodwork with dire warnings about passing off rank theory as fact?
All over the place. They just aren't connected to religion (or at least not major religions), so they don't get the microphone of a major religious organization.
Hang out on one of Usenet's science groups, or look through the archive, and you'll find all sorts of kooks with all sorts of theories "proving" QM, or General Relativity (link to examples), or Gravitation, or the accepted theories of Cosmology, wrong.
The thought has crossed my mind that more people would be more upset about physics if they realized how thorougly it contradicts their ideas about how the universe works, and really, that statement isn't just limited to the religious, either. But most people live in varying states of blissful ignorance, and ultimately, that's probably just fine.