Posted: Sep 14, 2011 7:19 pm
by eric8476
twistor59 wrote:By "conclusions of schrodinger", you presumably mean Schroedinger's cat experiment, not the conclusions of Schroedinger himself. If so, then I wouldn't say "disproving", but rather "highlighting a problem with":

The atom is in a quantum superposition (decayed+not decayed). There would then be a long causal chain of interactions leading to the eventual state of the cat. The atom in the gamma ray detector would be in a superpostion of detected+not detected. The electric current would be in a superposition of generated+not generated. The motor would be in a superposition of in motion + not in motion etc. All the time along the chain the items are getting bigger -- less microscopic and more macroscopic.

We know that we never see cats in a superposition of states. The question is therefore - "where along the causal chain do the rules of quantum mechanics break down and superposition gets lost" ?. This is the "Measurement Problem".

There have been many proposed answers to this over the years, and if you want an animated physics coffee table discussion, this is one topic guaranteed to bring it about.

the activity of the atom does not put the other functions of the experiment in superposition. the gamma ray detector detects what is given. when of if the atom goes into superposition the point in time the atom demonstrates a decayed point would be detected or else the atom does not go into superposition (i.e. it is not both decayed or not decayed because it would not have demonstrated the decayed status).

hackenslash wrote:Computers, or more specifically the semiconductors in computers, employ devices known as Esaki diodes, which operate on the basis of quantum tunnelling. Of course, I already addressed this in the previous post of mine you quoted.

do the elctrons permiate through the barrior? do the electrons change their shape to slip past the solid barrior? whoever reads this make sure you credit me when you present your nobel prize presentation. hehehe

hackenslash wrote:I see that Twistor has covered this in more depth than I would have done.

get into it, come on, use the thought experiment to exercise your mind. :grin:

hackenslash wrote:It isn't used to measure the wavefunction, but to describe the probability amplitude of one of a pair of conjugate variables.

hhhhmmmm, thanks.

hackenslash wrote:Care to highlight the distinction, or to point out how one can measure something without observation?

a observation is when you look at a leaf falling from a tree. a measurement is calculating the velocity of the fall.

hackenslash wrote:It isn't a matter of technology, and your continued reassertion that it is doesn't actually move us forward. Indeed, there's good reason to think that those conjugate variables don't actually possess any definite values until observed.

do you think the electrons passing through a double slit know that they are being watched? or is the measuring device interfering with the electron flow.

is it a new form of functioning life? is it a new form of functioning conciousness? does it explain conciousness we have, like wondered about in another thread? that would explain why we are looking for a "God-particle". hehehe

this could also disprove a notion of a God with proving conciousness function.

hackenslash wrote:What?

the result is what happens at the conclusion of the experiment. it could be observable, measurable, both or neither, but it is a result none the less.

hackenslash wrote:I'm aware of them, thanks. There are problems with those that don't include the collapse of the wavefunction. Not insurmountable by any means, but suggestive of problems. For example, the Many-Worlds interpretation is horribly unparsimonious. Not that parsimony is indicative of veracity, but as a heuristic in hypothesis selection, it's proved extremely useful, so not to be dismissed lightly. the de Broglie-Bohm intepretation runs into difficulties with the observation of superposition (indeed, and as Darkchilde pointed out above, it has been observed in macroscopic objects), because superposition removes the need for the 'pilot-wave'.

I tend to favour the path integral formulation, but not with any huge conviction. Since they are pretty much inseperable in terms of prediction of observations, there's no reason to choose between them at this point, but those without wavefunction collapse are the easiest to lay aside until some unique predictions arise from one of them. The Copenhagen interpretation has brought us a very long way, and those hypotheses haven't actually brought us any further (apart from the path integral).

In any event, none of this supports your assertion that measurement and observation are different things.

i think quantum mechanics needs more ways of looking at things that can be calculated and/or proven. some of the ideas now are confined to speculation too much. - "3. The dimension, quantity, or capacity determined by measuring". factors not needed for observing. - it's noticing something.

hackenslash wrote:They can certainly be observed, but they can only be observed with a given position or a given momentum, not both. The very best we can do is a kind of weak measurement that can give a vague average of both, to the tolerance of the wavelength of the photon used for observation, but accuracy is impossible, because the uncertainty principle cannot be violated with pairs of conjugate variables. The more accurately we know one, the less accurately we can know the other.

yes, the more we know about a position, the less we know the momentum and vise versa. but if a measuring device can view and record the electron cloud space and the electrons in motion without stopping the electron, the momentum can be noted and the position can be noted after viewing the pausing of a recording.

hackenslash wrote:And the evidence in support of this contention is...?

Since there is good reason to suppose that pairs of conjugate variables don't actually possess values until they are observed, I'd love to see how you're going to manage this.

if you asked an educated person in the renaissance timeperiod about eluminating a place at night that person would not have an idea about the light bulb. catch my drift?

Darkchilde wrote:There is a problem here. Once the wavefunction is observed, by anything, even by a photon or by an electron, or a device, then the wavefunction collapses to one of the associated probabilities. A device that observes that does not collapse the wavefunction, would be one that does not do any observation. The mere act of the device's observation is the one that will collapse the wavefunction.

if there is superposition, a device could be programmed to factor in the different eigenstates and filter it or factor in the eigenstates or factor in the in between of eigenstates altogether.

are you saying the use of the particle that a wavefunction is for collapses the wavefunction?

zaybu wrote:There's one problem with these explanations: the wave function is NEVER observed. Observables in QM are operators, such as position, momentum, energy, spin. The wavefunction is just a mathematical tool that allows calculation of expectation values of these observables. Any other interpretation of the wavefunction is just pure speculation, unsupported by any evidence.

if a particle can be noticed without disturbing the superposition, collasping the wavefunction is not pertinent.