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| quote: | Originally posted by St_Andrew
The only thing i say is that we COULD predict ones choices if we knew all the variables. Now, that is obviously not possible (with todays knowledge and probably not with tomorrow's either). But in theory we can do it... And theoretically we CAN predict also all the random factors, even though that is practically IMPOSSIBLE. But in theory it should be fine. even though also that is wrong for some reason, it doesn't contradict my theory, free choice doesn't exsist and we are only slaves to our environment (and in that you could possibly also count in randomness) and our brain. |
And the only thing I say is that you are factually wrong and don't understand the counter-argument. It is NOT possible, not even theoretically, because you can't know the contents of an infinite set! Also, you can't predict random variables, no matter what you say. It is not a practical limitation - it is a theoretical impossibility!
| quote: | Originally posted by NeoPhono
I'm going to be anal here (computer engineer in me coming out), and yes this is a little off-topic.
The Heisenberg uncertainty principle only relates to actions on a quantum level, not a macroscopic one. It states that the more precisely a position is known, the less precisely the momentum is known. Actually though, this has been under quite a lot of debate recently, as this postulate was constructed before much of what we know of quantum mechanics was known. Today it is believed that you can know both position and momentum of subatomic particles to such a high percentage of probability that you can in fact know both position and momentum for "practical" purposes.
My main point is that it only applies to non-macroscopic applications. It would suck if you saw a car coming towards you and could tell where it was, but not how fast it was coming at you. I personally think that the unertainty principle will one day be disproven, or at least pushed back to a realm where our oberservation abilities do not allow clear perception. Is our universe deterministic? I don't know, but I find it very hard to concede that it is purely indeterminite. Star Trek transporters...here we come!!!
Just on a side note, may people state the uncertainty principle as having to do with oberservation. In example, someone will say "the act of observation changes the state of a function, and makes measuring it accurately impossible." That is actually untrue, as even without observation, it has been shown to be impossible to know both position and momentum.
If you're interested in this kind of "stuff," I recommend read about the EPR paradox, the Bell inequality or the hidden variable theory...all very intersting, almost philosphical science questions along these lines. |
I'll have to read about those bottom things to really understand, but here is my attempt to clarify:
Yes, it's true that we can know both position and velocity in a macroscopic sense, like a car coming down the road. However, this doesn't defy quantum principles - the issue with a car is that there is uncertainty in your reference point. You have an almost precise measurement of speed, but how accurate is your measurement of position? You can't calculate the position of a "car", because it's a composite object. Which point on the car? Are you talking about the position of the windshield, the stereo, the driver's seat? I guess, if you're trying to avoid being hit by that car, you'd be taking the front bumper? But which point on that front bumper? If that car was accelerated close to the speed of light, then the front and back of the car would actually be moving at different speeds on a macro level.
The further you try to narrow down your reference point, the more uncertain you are about exactly how fast it is going. Quantum principles still apply on a macro level, they just aren't noticeable.
I would like to see the source on the belief that we can know both the position and speed of a particle to equally high percentages. I believe that it has in fact been proven that we cannot. You have to understand that the HUP doesn't refer to "uncertainty" as such - it refers to randomness. The probability of position and velocity are distributed over certain intervals. Make one interval smaller, and the other gets larger. It is not a matter of "knowing" where they are, it is the concept that these particles are actually wave functions that take on random behaviour.
The most often cited proof of this is the "pinhole" experiment, where light is refracted through a very small slit. It's been shown repeatedly in labs to college students that when you project single photons through that slit, and have a screen behind the slit to collect the photons, they will actually form diffraction patterns - that is, the light will not be focused on any particular spot, but rather there will be a distribution (diffraction pattern) on the screen which is stronger at some points and weaker at others. The smaller you make this slit/pinhole, the larger the diffraction pattern. Specifically, the more you restrict the position of the original photon, the less you know about where it's going to go (velocity).
Conclusion: The HUP is a pretty well-studied and well-proven principle that isn't likely to be disproven any time soon.
But, I'll take a look at those things you mentioned and see if that changes anything... for now, I say that there are too many things wrong with the determinism concept:
1. There is an infinite set of variables and we can never figure out an infinite state.
2. There is a finite amount of uncertainty in those variables that we can never get around.
3. Even if we could get around 1 and 2, there is still visible random behaviour, i.e. as shown in the pinhole experiment. Even if you could find an exact state at one instant in time, the state at the next instant in time is random.
Hope this all makes sense. 
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