- 8
- 0
..........
Last edited:
Basically, an interpretation of quantum mechanics formulated by Bohr and Heisenburg that ended up solving some problems in physics (wave-particle behavior experienced by Michaelson's experiments) by inducing a couple principles, such as the Uncertainty Principle, the instantaneous collapse of the wave function, and the indeterministicism of measurement outcomes, and so on. Very basicly.slyboy said:I'd be interested to know if anyone who voted for the Copenhagen Interpretation can give a coherent explanation of what it actually is.
Of course, I know what it is, but I am extremely surprised to see that the majority of people are voting for it. Copenhagen, at least as it was formulated by Bohr, is a really rather radical view of the world that is not necessitated by the formalism of quantum mechanics per se. Nor is it accepted by the vast majority of physicists, at least not if you quiz them about its principles in any great detail.Basically, an interpretation of quantum mechanics formulated by Bohr and Heisenburg that ended up solving some problems in physics (wave-particle behavior experienced by Michaelson's experiments) by inducing a couple principles, such as the Uncertainty Principle, the instantaneous collapse of the wave function, and the indeterministicism of measurement outcomes, and so on. Very basicly.
Quantum mechanics has the measurement problem to worry about. There is no well-defined way to just "rely on the equations" in textbook quantum mechanics. You have to define an external classical observer, and say exactly what he is "measuring" for all times. It disturbs people that a supposedly fundamental theory seems to require the existence of a poorly defined entity that is external to it.masudr said:Why don't people worry about an "interpretation" of classical mechanics? People tie themselves up by talking about such an interpretation or another. Instead rely on the equations, they will only fail if QM as a theory is generally a false model.
It doesn't matter what disturbs people. It disturbed people that the earth wasn't at the centre of the universe. So what?Stingray said:It disturbs people that a supposedly fundamental theory seems to require the existence of a poorly defined entity that is external to it.
Wavefunctions exist as superpositions until observed. Why is that hard to swallow? Two interacting systems exist as tensor products of the individual system until observed. Why is that so hard to swallow?Stringray said:If it is fundamental, quantum mechanics should be applicable to all systems, and the various interpretations attempt to clarify these sorts of logical issues (at least the worthwhile ones do). Classical physics obviously does not have the same sort of vagueness about it, so interpretations aren't as necessary.
Richard Feynman said:masudr said:As a mathematical physicist, I don't think interpretations matter. Schrodinger's equation will always exist as a fundamental concept of QM. So we can use it! And that's all that matters, in my opinion.
It's hard to swallow because it's not necessarily obvious when an observation takes place, or which quantity is being observed. In the end, you are of course trying to predict the values of certain observables, so your final experiment must be unambiguous. What happens at intermediate times though? You presumably start with a superposition and then what? Is it assumed that there can be no intermediate observations, and that one simply lets the wavefunctions of all the various systems -- microscopic and macroscopic -- interact through Schrodinger's equation (in principle)? I don't think this is mathematically equivalent to allowing multiple observations, but it should be.masudr said:Wavefunctions exist as superpositions until observed. Why is that hard to swallow? Two interacting systems exist as tensor products of the individual system until observed. Why is that so hard to swallow?
Good point, although I don't think vague is the right word to describe that. It is still straightforward to apply the formalism. Or am I missing something?Classical mechanics does have the same sort of vagueness. For example, we immediately assume that the position of particles are represented by real numbers, and all motion can be described in terms of infinitesimals. These are not reasonable assumptions. In my opinion it is just as vague.
This is all good and well, but we will never understand nature. If classical mechanics was true, we still would never understand nature. There are an infinite possible kinds of universe that could exist (whether or not we would exist in them is another matter).ashfaque said:I would very much like to understand nature. That's why Interpretations matter to me.
In classical mechanics the interpretation belong to common sense.Though we might be not aware of that we do attach a proposed ontology to the mathematical formalism.In QM common sense interpretations do not exist thus we have,if we want to go till the end and complete the program,to attach a proposed ontology to the standard mathematical formalism of QM.Unfortunately there exist more ontologies compatible with observed facts,the most coherent with GR being,currently,the Copenhagen interpretation,in spite of its logical positivist nature (this does not amount to say that it has more empirical support than the other acceptable interpretations of QM).masudr said:As a mathematical physicist, I don't think interpretations matter. Schrodinger's equation will always exist as a fundamental concept of QM. So we can use it! And that's all that matters, in my opinion.
Why don't people worry about an "interpretation" of classical mechanics? People tie themselves up by talking about such an interpretation or another. Instead rely on the equations, they will only fail if QM as a theory is generally a false model.
There is nothing common-sensical about classical mechanics. The only reason it seems like it makes sense is because we have perceived a reality since birth that complies with the ideas set forth by classical mechanics.metacristi said:In classical mechanics the interpretation belong to common sense.
Yes what about him? give a link or explainashfaque said:ashfaque:
What about Shahriar Afshar's experiment and the Refuttal(?) of the Copenhagen Interpretation?
Stingray said:Stingray
masudr said:Originally Posted by masudr
Why don't people worry about an "interpretation" of classical mechanics? People tie themselves up by talking about such an interpretation or another. Instead rely on the equations, they will only fail if QM as a theory is generally a false model.
Quantum mechanics has the measurement problem to worry about. There is no well-defined way to just "rely on the equations" in textbook quantum mechanics. You have to define an external classical observer, and say exactly what he is "measuring" for all times. It disturbs people that a supposedly fundamental theory seems to require the existence of a poorly defined entity that is external to it.
I agree that this is not usually a problem in practical applications, but the fact remains that we can imagine situations where the concept of a measurement device in the textbook sense does not exist (e.g. quantum cosmology). If it is fundamental, quantum mechanics should be applicable to all systems, and the various interpretations attempt to clarify these sorts of logical issues (at least the worthwhile ones do). Classical physics obviously does not have the same sort of vagueness about it, so interpretations aren't as necessary.
Here is a Newtonian Mach. interpretation for youmasudr said:masudr:
There is nothing common-sensical about classical mechanics. The only reason it seems like it makes sense is because we have perceived a reality since birth that complies with the ideas set forth by classical mechanics.metacristi said:Originally Posted by metacristi:
In classical mechanics the interpretation belong to common sense.
...
Finally, this has brought up an interesting issue. Does classical mechanics allow only one interpretation? I'll have to think about that one before I answer, so I thought I'd throw it open to the forum.