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The Copenhagen interpretation
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by
on 2007-07-20 12:23:15 (edited 2007-07-20 12:42:00)
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What are your thoughts on the Copenhagen interpretation of the quantum mechanics? Does it follow from Bohr and Heisenberg's argument that the task of physics is to find out what we can say about nature, not how nature is? Is there an underlying reality of both the position and momentum of a particle, wether measurable or not, such as Einstein insisted? Do we have to give up Determinism in acceptance of the Copenhagen interpretation? Why is or isn't the wave function the real nature of particles? Notice that I have posted this thread in the Physics topic, which means that philosophical arguments, to the extent that they have nothing to do with physics, should be avoided herein. I understand that this issue is largely philosophical in nature, so I expect people to use their judgement. For example, I would be displeased to hear, "I think nature is deterministic so the Copenhagen interpretation must be wrong", but very pleased to hear, "the study of physics relies on determinism insomuch as it can be used to describe natural phenomena". Notice the difference in objectivity and preconception. 
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Re: The Copenhagen interpretation
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| ah rats I did a paper on this, I think I still have the file save on my comp... sighs... Are you by chance majoring or taking course for physics? Or just a fan of science like me |
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Re: The Copenhagen interpretation
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by
on 2007-07-28 17:40:06 |
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I took a modern physics class my senior year in college, but it wasn't my major. Feynman got me hooked, really. I've read all the physics books I have come across.
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Re: The Copenhagen interpretation
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Sorry if this is off topic, can you recommend some physics you read and enjoyed? oh and sorry again I couldn't find the paper I had, it must of been when I had to system restore my comp... Sometimes I browse the web universities and read other students/professors research on quantum physics, if you would like to read more into it. |
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Re: The Copenhagen interpretation
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by SuicidopoliS
on 2007-07-30 06:12:37
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To begin with, i don't know very much about quantum mechanics. I've just studied the basics though, as well as the history behind Schrödingers formula. I've always felt the Copenhagen interpretation is a bit of a weird thing, but then again, i'm far from being the only one. When you study quantum mechanics, you're told that the Copenhagen interpretation is the only possible interpretation ( opposed for instance to the spread-out electron interpretation ), even though it may seem weird. And obviously, i'm unable to come up with something better, so yes, i do accept it, but nevertheless... it is just a weird thing. Especially the fact that it seems to make sense ( read: experiments tend to aknowledge it ) for the microscopic world, but it doesn't work for the macroscopic world. If i throw a ball in an open space here on earth, and i give you it's velocity and acceleration and stuff just before it hits the ground, you'll be perfectly capable of calculating where i was standing when i let go of the ball, so there isn't any notion of "or i know the ball's exact position, or i know it's exact velocity, but i can't know them both at the same instant". You'll know them both, at every instant of time during it's trajectory. The whole Copenhagen interpretation also led to this idea/question of: "does something ( say: the moon for instance ) really exist when i don't look at it?". Quite frankly, i do believe the moon will still be there when i don't look at it. I do believe, and even find comfort in that idea, that when i leave my room, and no one, no "observer", is indeed observing the stuff in my room, it'll still be there when i return. And up till now, that has always been the case... And in a way, how could the Copenhagen interpretation be proven wrong? I mean, if you measure a particule's position/velocity, you're bound to get an outcome, you're bound to find your particle somewhere ( it's one of the fundamentals of quantum physics! ), so if you assign a probability to every position in space ( which in a way is what the Copenhagen interpretation does ), you'll always get a correct answer, because every position is possible. And there's obviously this weird time paradox with Schrödinger's Cat... Say i put a cat in a box for 3 days, i then open the box, and find the cat to be dead. So, at the very instant i observe the cat, the wave function will collapse, and will make the cat dead ( considering my presumed outcome ), and thus, will also affect what happened in the past. If the cat "was dead for a day", or rather, if the wave function decides to kill the cat yesterday ( i know, it's an awkward formulation ), then at one single instant of time, you're affecting the past, which is quite frankly obscure to say the least. I do however fully agree that the task of physics is to describe Nature, and try to explain how it works, but in no way try to come up with a reason why it works exactly that way. In a way, i think that would be useless anyway. Suppose we humans would've evolved to have 3 eyes, instead of 2, and that that would be the only reality we know, we would've found it to be just as natural as we find it now to have 2 eyes. My point is: i believe in a certain arbitrairness ( how do you write that work anyway? ) in evolution ( be that of mankind, or the universe ) that simply can not be explained properly. Conclusion: we shouldn't give up the Copenhagen interpretation, because it worked in so many cases, but a more profound understanding of it seems mandatory to me. Right now, it really feels like the micro- and the macroworld are 2 completely separate things, with their own laws and behaviours, and the fact that they are in fact both different aspects of the same reality seems more like magic, then like anything else at the moment. .oO° Life's THE CURE, the rest are details! °Oo. |
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Re: The Copenhagen interpretation
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by
on 2007-07-30 12:52:29 (edited 2007-07-30 13:01:45)
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I like your analogy of throwing a ball on earth. There is no noticeable error in measuring the velocity of the ball due to the effect of measuring the position of the ball. Of course, this is in agreement with uncertainty, because plank's constant is so very small. Photons are bouncing off the ball from the sun and all over, but not effecting it's trajectory or position by any measurable amount, given modern measuring devices. But when we look at an atom, or subatomic particle, it becomes more noticeable! I agree with you that if you leave a room, the room is still there, waiting for you to return. But, when you're not looking, someone might have tampered with the stuff in the room. The only way to know for sure is to observe the whole time, but even then, you can't see every corner of the room at once! At some point, this starts to sound more like the ramblings of a paranoid person than scientific conjecture. XD Well, I'm not even sure I know what the Copenhagen Interpretation actually IS, but I know it is NOT a theory. It doesn't claim to be. It claims to be an interpretation of the THEORY of quantum mechanics (which is inarguably a successful theory!). The difference being, it assumes no predictable effects, but rather, explains those made by quantum mechanics. It is the philosophy cooked up by these guys in Copenhagen to resolve the dissonance between the equations of QM and human ideas of reality. It worked for them, but I'm not sure if it works well in our time. It almost, but doesn't quite, work for me. I think I have come across an explanation for the cat paradox!!! Whenever we imagine a scenario in our heads, there are IFs. Each IF is a fork in the possible outcome. These IFs do not represent multiple possible realities, they represent multiple possible MODELS for the ONE TRUE reality. Obviously, you can't ever escape this reality and land in another one, take sample data, then go back home. So, the thought experiment does not model reality, it produces many models of it. The cat being both alive and dead is a state, a model, that we cook up. It helps us predict the condition of the actual cat. It's handy to think this way, but we aren't so foolish as to actually BELIEVE our model to be correct. What does a cat look like which is half alive and half dead? Obviously, in opening the box, you have not effected the past. It seems what is truly effected is your MODEL of the past. It is the MODEL that can exist in mixed states, to great effect. A poker player would likely understand this: The opponent's hand contains not cards, but probabilities of cards. Once you see some cards turned out, the probabilities of the opponent's cards is narrowed down. I get afraid when I here people talk about quantum mechanics in a literal way. Our tricks and tools for describing nature should not substitute for reality. They are useful to us as scientists in a similar way as scripture is useful to the religious person. Tools for understanding and making choices, sure, but not laws to be believed in with blinding conviction. That's dangerous and unhelpful.
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