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In quantum mechanics, wave function collapse is said to occur when a wave function—initially in a superposition of several eigenstates—appears to reduce to a single eigenstate (by "observation"). It is the essence of measurement in quantum mechanics and connects the wave function with classical observables like position and momentum.
I came across this thread https://www.quora.com/What-does-it-mean-to-say-a-wave-function-collapses at the Quora forum. The first person on the list writes: When people say that "the wavefunction collapses", that means that they don't understand how quantum mechanics works. Frankly I find comments like that not only rude but ignorant and the person who says it being arrogant. Most textbooks speak of the collapse of the wave function.To be clear on what it means see: Wave function collapse at https://en.wikipedia.org/wiki/Wave_function_collapseQuoteIn quantum mechanics, wave function collapse is said to occur when a wave function—initially in a superposition of several eigenstates—appears to reduce to a single eigenstate (by "observation"). It is the essence of measurement in quantum mechanics and connects the wave function with classical observables like position and momentum.
....Typically, this involves interaction with other quons and brings about a situation similar to the older idea of a collapsing wave function. No conscious observer is necessary for this.
I have not had time to follow the link yet; but is this a question of semantics?
The reasoning seems to go something like this: Instead of arguing that the intervention of a conscious observer causes the wave function of a quon to collapse;...
What's a quon? Do you mean "Quon = quantum entity" as Nick Herbert defined it in his book "Quantum Reality"? If so then it's a very bad idea to use that term in a forum. He's the only person to use that term and only in that text. So there's no reason to expect others to understand it. It will only go on to create confusion.
Phrases like "wave function collapse" appear frequently in the vernacular. I often use phrases like this for expediency; but, they are technically incorrect. In quantum theory the so called wave function is not describing an actual wave. There is no wave. And nothing collapses.
In the Bohr interpretation the function only describes what characteristics are possible for a photon.
"Bohr never talked about the collapse of the wave packet. Nor did it make sense for him to do so because this would mean that one must understand the wave function as referring to something physically real." http://plato.stanford.edu/entries/qm-copenhagen/#MisCom
You need to read my post more carefully.
The quote is stating that the wave function is a mathematical tool and not a physical entity.
... this would mean that one must understand the wave function as referring to something physically real.
I f you disagree with the part about Bohr never using the term collapse..
There has been a recent hypothesis that has surfaced in which light exist as a superimposition of both the particle and wave states until tested for as one of those possibilities.
I believe that this is what you guys are reading. This is not orthodox theory and is far from achieving theory status. In its attempt to answer some new observations it has created more problems than solving them. Although I am always for new theories and it may develop into something.
You need to read my post more carefully. The quote is stating that the wave function is a mathematical tool and not a physical entity.I f you disagree with the part about Bohr never using the term collapse and it not being part of his original quantum theory; then you are in disagreement with the credentialed sources at Stanford University that were quoted.
You need to read more carefully.
A simple translation or paraphrasing would be: Bohr would never use the term collapse because it would mean he was talking about something physical which he did not believe was physical.
There are a lot of versions of quantum theory and when I see a simple question that I think I can answer I feel obligated to do so with the most accepted view, ..
Don't know if when you talk about Bohr ideas on collapse you also want to mean "Copenhagen interpretation and formulation of QM", however I have to inform you that the collapse is part of standard QM formulation fron 1932, with the work of Dirac and Von Neumann and his book "Mathematical Foundations of Quantum Mechanics":https://en.wikipedia.org/wiki/Mathematical_Foundations_of_Quantum_Mechanics.
they are technically incorrect. In quantum theory the so called wave function is not describing an actual wave. There is no wave. And nothing collapses.
I do not think that I insulted anybody.
Bohr never talked about the collapse of the wave packet. Nor did it make sense for him to do so because this would mean that one must understand the wave function as referring to something physically real.
"Wave particle duality" is another common but incorrect phrase.
The implications of this (which are described in Chapter 6 of Richard Feynman's The Character of Physical Law) are staggering.
This growing confusion was resolved in 1925 or 1926 with the advent of the correct equations for quantum mechanics. Now we know how the electrons and light behave. But what do we call it? If I say they behave like particles I give the wrong impression; also if I say they behave like waves. They behave in their own inimitable way, which technically could be called the quantum mechanical way. They have in a way that is nothing like you have ever seen before. Your experience is incomplete. The behavior of things on a very tiny scale is simply different. An atom does not behave like a weight hanging n a spring and oscillating. Nor does it behave like a miniature representation of the solar system with planets going around in orbits. Nor does it appear to be like a cloud or a fog of some sort surrounding the nucleus. It behaves like nothing you have ever seen before. There is one simplification at least. Electrons behave in this respect in exactly the same way as photons; they are both screwy, but in exactly the same way.
Wave–particle duality is the fact that every elementary particle or quantic entity exhibits the properties of not only particles, but also waves.
Louis de Broglie proposed that the wave-particle duality is not a monopoly of light but is a universal characteristic of nature which becomes evident when the magnitude of h cannot be neglected. He thus brought out a second fundamental fact, usually referred to as the wave nature of matter.
4.14 Collapse....But something different happens when an observation is made. An experiment to measure L will have an unpredictable outcome, but after the measurement is made, the system is left in an eigenstate of L. Which Eigenstate? The one corresponding to the outcome of the measurement. But this is unpredictable. So it follows that during an experiment the state of a system jumps unpredictably to an eigenstate of the observable that was measured. This phenomena is called the collapse of the wave function.
Bohr used something like the convergence of time distance intervals along vector lines to calculated the points for the greatest probability for photon occurrence. This is completely different than the historic calculations of crest to crest increase in amplitude for photon occurrence used in wave functions. His function is only referred to as a wave function out of the historical preference.
Oops: Finally got it. You were not objecting to the wave function as being a mathematical abstraction but to saying that using the term function collapse means that it is not. I guess I am the one who should read more carefully.
If you consider the wave function as only a tool for prediction then you are in agreement with prevailing theory.
Please accept my apology for miss-reading you if that is the case,
There are articles that have appeared recently with titles such as "Quantum Physics just got Easier to Understand" http://www.huffington.com/2014/12/24 . It is obvious from these titles that a new hypothesis is being presented.
Mordeth could certainly take lessons on humility from you, that's for sure.
I believe they are saying that light exist in two superimposed states as a wave and as a particle. I also believe they are saying that if you test, or measure, for a wave you get a wave and if you test for a particle you get a particle.
I believe they are saying that light exist in two superimposed states as a wave and as a particle.
I also believe they are saying that if you test, or measure, for a wave you get a wave and if you test for a particle you get a particle.
This is like saying the cat in the box will be dead if you test to see if its dead and alive if test to see if it is alive.
There are better answers to some of the recent experimental anomalies.
This idea has flooded the popular media and unfortunately I incorrectly jumped to the wrong conclusion that this thread was a back door attempt to introduce it.
dlorde: I am sorry I am late responding to your post; I was distracted.
The statement that a clear explanation will arrive in time is right on. The current technique of observing photons in transit with energy to low to disrupt the field ( this is contradictory to existing theory on several levels ) is opening up a window into light behavior. In a few years the concepts we are currently discussing may only be foot notes to history.
"Everyone thinks they know what light is and everyone is wrong", Einstein.