...or you can read my accidental explanation of it to a friend about 8 years ago:
Date: Thu, 9 May 2002 12:58:52 -0700 (PDT)
From: "Jennifer G."
Subject: Re: If you want to know write me w/ your ideas!!!!!!!!!!!
To: "Daniel Y."
For once I'm stumped - what is it? (can you smell my baited breath? As a cat lover I do have extra lives but I've used up many of them doing the Schrödinger experiment [ask only if you really want to know], so don't get me so curious that I lose some in non-scientific pursuits...)
To: "Jennifer G."
Date: Sun, 12 May 2002 22:29:42 -0500
Subject: Re: If you want to know write me w/ your ideas!!!!!!!!!!!
From: "Daniel Y."
My my my I have Jennifer stumped this could be BIG NEWS!!!! So what is
this experiment that you were referring 2???? What it is the entire
sentence is completely able to spell it the same forwards and backwards so if you start and take it backward and it spell the exact same both ways. Something like Hebrew I don't remember a friend explained it and I forgot it.
Date: Tue, 21 May 2002 21:07:56 -0700 (PDT)
From: "Jennifer G."
Subject: Re: If you want to know write me w/ your ideas!!!!!!!!!!!
To: "Daniel Y."
Sorry I took so long to respond. Here is a further explanation of the
Schrödinger's Cat experiment (if this is boring, remember that I warned you not to ask) :
There is a really weird phenomena in quantum physics that proposes the non-existence of causality. Causality is the idea that events are caused by previous events in a predictable fashion. Causality lies at the root of logical reasoning - we know one thing beCAUSE we know some other thing. [6/7/10 - I think I was saying this because statistics are different than black and white causality. Actually, I now think it a bit presumptuous to say that quantum physics threatens causality.]
I don't remember who the physicists were (I'm thinking this is the Young double-slit experiment), but some physicists set-up an experiment that brought causality into question. Imagine a sheet of bullet-proof glass w/2 holes drilled in it. Stand this thing in the middle of a room and shoot a bunch of bullets at it and you make two regions of bullet marks on the wall behind the bullet-proof glass, each region corresponding to one of the holes you drilled. Now set this thing in a bin of water, the water level even with the holes. If you make a wave on one side you will notice that when the wave hits the holes a two new waves are begun on the other side of the glass, one corresponding to each hole. After a certain distance these waves will meet and interact with each other. Some of the peaks of one wave will add to the peaks of the other wave, creating a larger wave, and some will cancel with the troughs of the other wave, creating a flat zone. Some of the troughs will also add to the troughs of the second wave, creating a trough twice as low. This is call a wave interference pattern.
Electrons, most sub-atomic particles in fact, are know to have a property called wave-particle duality. This means that an electron behaves as both matter and energy simultaneously - though in reality it may be neither. So, we redesign the above experiment as a sheet of some material with two slits in it. The slits are very small, ideally they will be slightly larger than the diameter of one electron. Electrons are shot at this thing, and some electron-sensitive device on the other side will record the pattern produced. The funny thing is this: if we observe to see which hole the electrons are passing though, we'll get a pattern as if we were shooting bullets. If we don't make any such observations, we'll get a wave-interference pattern. Even if we shoot the electrons one at a time we will still get a wave pattern when we don't observe which slit the electron goes through (How does one electron interact with itself to produce a wave pattern?). After repeating this experiment many times in many forms, most physicists have concluded that sub-atomic particle behavior is governed by statistical rather than absolute laws, and the wave-interference pattern is often considered to be a statistical wave. The peaks represent areas where there is a high probability of finding the electron, the troughs represent an area where there is a low probability of finding the electron. But where is the electron really?
This is the question that Schrödinger wanted to answer. He decided that thinking about this whole business at the particle level was rather confusing, because after all, nobody really knows just what particles are, and everyday experience does not lend us intuitive expectations for their behavior. So, he devised a thought experiment that brought the puzzling question into more familiar terms. We imagine a box that is completely sealed, and is not transparent or anything like that. There is no way for us to know what is going on inside the box once we close it. The box contains a cat, and a glass globe containing a lethal amount of cyanide gas. There is a hammer poised to break this globe. The hammer is connected to a device that is sensitive to radiation. If a certain amount of radiation is detected within a certain time limit, the hammer will fall and the cat will die. Otherwise the cat lives.
Radiation is actually particles being ejected from an atom. The rate of radioactive decay for any given sample is fixed, but it is a statistical rate. Whether or not the radiation is actually emitted is a matter of probability. Therefore, when the cat is locked up in this box and the sensor is exposed to a radioactive sample, the question becomes is the cat dead or alive? The most plausible answer given (I believe it is called the Copenhagen interpretation) is that until we look, the cat is simultaneously dead and alive. Really it is the same question as "If a tree falls in the forest, and no one is there to here it, does it make a sound?", only Schrödinger wanted to use a cat, and he connected it with a known physical dichotomy.
This idea could have very far reaching consequences because the entire universe is made up of particles. If they all behave in this statistical manner (and if one of any given type does, then all particles of that type should be the same throughout the universe), then it is very possible that there are zillions of worlds in "existence," and "reality" is created by an observer, who in effect forces the statistical universe to exist in a single, absolute state.
At the philosophical level, this can be interpreted many ways. Some people would say that this means that truth and all values are relative, that people are master of their own fate and of values themselves. However, there are other questions entirely about what happens when more than one observer is at work. Perhaps only one observer can "force" a statistical universe to choose its course, and then things are set from there on. This argument is sometimes used to "prove" the existence of one, omniscient, creator God. I like to believe that this physical dichotomy holds part of the answer to the dichotomy of predestination (which follows from God's existence), and free will (which follows from our being created in His image, and especially of individual responsibility for sin). Then again, perhaps the physical world is too different from the spiritual for such analogies to be really meaningful. Anyway, that is Schrödinger's Cat, where it came from, and what it might mean.
Hope I didn't kill your eyes.
~Jennifer
PS - I'll have to go back and look at the sentence. That is really amazing that someone constructed a coherent sentence that long which is also symmetrical. Cool!
To: "Jennifer G."
Date: Sat, 25 May 2002 00:14:58 -0500
Subject: Re: If you want to know write me w/ your ideas!!!!!!!!!!!
From: "Daniel Y."
You're right that is magor [sic] boring and very into math of which I'm not.
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Original MySpace comments:
What would I do without the internet??? Anyway, here's fascinating discussion of the Heisenberg Uncertainty "Principle" This is the best discussion I have yet seen of the Heisenberg Principle. Being part of the Stanford Encyclopedia of Philosophy, perhaps it is not surprising that I get the feeling that Heisenberg was infected with logical positivism/Wittgensteinism. Mind you, I'm still not entirely sure what either of those stand for, but I believe they were roundly (or squarely, whichever you prefer) defeated by Godel. Perhaps I prefer the Bohr explanations?
6 months ago
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Well, before I move on to the next blog, I just figured I post this. It's something I made, thinking I ought to turn it into a T-shirt or bumper sticker. It's a purposefully obscure reference to introversion:
6 months ago
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Ha! I found it:
"We are able to see a bird in flight because of the reflection of photons of light from the bird to our eyes. We certainly would not expect those photons striking the bird to alter it's path in any way. However, to detect an object as small as an electron requires photon of very short wavelength (high energy) such that the speed and position of the electron will be changed the moment the photon strikes it. This is not unlike trying to detect the position of a bird in flight by firing baseballs at it; obviously the bird's position and speed will be disturbed when it is struck by a baseball.
Heisenber's uncertainty principle theoretically holds for all objects, but like matter waves, it becomes important only for very tiny particles like electrons. In effect, the result of this principle was to produce a model of the atom in which the electron had a certain probability of being found at a given region in space; it was futile to attempt to describe electron behavior precisely."
-Ch. 8 of Chemistry: Precison and Design (A Beka Book Publishers, version unknown)
On the flipside of that same page, in a section of it's own, was a very nice pieces written by Feynman, which reminds me of one of my favorite quotes:
Sir Arthur Eddington summed up this situation brilliantly in his book The Nature of the Physical World, published in 1929. "No familiar conceptions can be woven around the electron," he said, and our best description of the atom boils down to "something unknown is doing we don't know what." He notes that this "does not sound a particularly illuminating theory. I have read something like it elsewhere-
The slithy toves
Did gyre and gimbal in the wabe"
From In Search of Schröedinger's Cat, by John Gribbin
So, my HS Chemistry text really did mention the Heisenberg uncertainty principle. And I rather misremembered the passage. But hey, cut me some slack, that was 12 years ago. I'm lucky I remembered it at all! Furthermore, I don't think I remember anything like that from my college textbooks ...though, there was this one rather beguiling proof for the law of refraction in my optics textbook, which showed quite clearly that a straight line is not always the quickest path between two points. It gave me some rather interesting thoughts on the nature of time, too, though I can't remember just what that was all about at the moment... oh, well. Next blog! ;-)
6 months ago
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On the subject of measurement, I really ought to briefly address the Heisenberg principle. Most people talk about talk about it as a sort of weird limit that doesn't allow you to simultaneously measure velocity and location at the same time, and the math basically looks at it like that. However, I remember a brief explanation in my high school chemistry text that explained it something like this:
Bats see by bouncing sound waves off of physical objects, and "seeing" the feedback. We see by the results of photons bouncing off of objects all around us. Imagine if you tried to look at a bird by bouncing baseballs off of it - would you be able to measure it's speed and position this way? It's speed and position would change as soon as you started "looking" at it. A photon is much larger than an electron, so we can't tell the the speed and the position of the electron by bouncing photons off of it.
Now, maybe the book was wrong, or maybe I'm just misremembering (I should go back and find this, I think I still have the book), but there are some problems with this explanation. First of all, if you tried to "measure" a bird's speed or velocity by bouncing baseballs off of it, you probably wouldn't be able to measure either. The Heisenberg Principle DOES allow us to measure one or the other. Second of all, it's hard to say that a photon is "bigger" than an electron, since it is more-or-less a massless particle. It may be correct to say that it is more energetic, but I'm not sure if even that is always true. Anyway, I still think that the analogy gets you to think about what's going on, more than some formulaic rule which simply states "it can't be done." Granted, no one is really sure how to look at particles without disturbing them, but perhaps there is a way. At least, this is how I always tended to think about it. Though, in college it was never presented as if there was any possibility of circumventing the problem through a variation in methods, and I generally didn't feel like speaking up in class to probe issue further.
After graduation, however, someone did show me this article. So, apparently, I hadn't been the only one to consider the possibility that "unknowable" things might be discoverable if only you could come up with a proper method of observation. Another cool thing is that they were doing the double-slit experiment with photons! I had only ever heard of it being done with electrons, previously. Furthermore, I would've thought that photons, being massless particles, would be more inclined towards behaving as waves rather than particles. So, generally, it's surprising to see that electrons can behave like waves. But, in this case, it re-surprising to discover the wave-duality nature of things seeing that photons can act like particles!
5 months ago
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