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kostas230
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I'm studying quantum mechanics and I can't seem to understand what qualifies as an observer. Does the "observer" need to be a conscious one? Yes or no and why? Thanks in advance :)
kostas230 said:I'm studying quantum mechanics and I can't seem to understand what qualifies as an observer. Does the "observer" need to be a conscious one? Yes or no and why? Thanks in advance :)
kostas230 said:[...] why?
Here you defined observation as interaction/measurement, which can sometimes leave people with the wrong impression, that interaction alone is enough to collapse the probability wave, which it absolutely isn't. Only measurement collapses the probability wave, and then only for the property for which the state of the particle is thus known. Thus in the double slit experiment you could interact with, and measure the particle, until the cows come home, you could knock the heck out of it, but if none of those measurements gives you which path information, then the interference pattern isn't going anywhere. The probability wave ain't going to collapse for just any old measurement, it's got to be specific. The particle somehow seems to know what you're measuring, but not only that, it also seems to know what you may indirectly learn from that measurement. So while the observer may not need to be a conscious one there appears to be more going on here than merely, I measure it, it collapses.DennisN said:No. Observation in quantum mechanics means interaction/measurement with e.g. an instrument in general.
While it's true that we can easily build a photodetector to "see" the particle in question, in what way is this evidence that such a detector could collapse the probability wave? The last time that I checked, every biological photodetector is connected to a biological brain, and who's to say that it's not the latter that actually collapses the probability wave? Is there indisputable evidence that detection alone collapses the probability wave?DennisN said:Hmm. Let's try this: You have many small (biological) photodetectors in your eyes, which enables you to detect light. But we can build a lot of other kinds of photodetectors, which obviously are not conscious.
Fiziqs said:I don't really mean to imply that a conscious observer is absolutely necessry to collapse the probability wave, but I do have a couple of problems with your answer.
Fiziqs said:[...] So while the observer may not need to be a conscious one there appears to be more going on here than merely, I measure it, it collapses.
Fiziqs said:It does seem logical that there is no need for a conscious observer, but is there evidence?
Fiziqs said:After all, this is science, right?
meBigGuy said:Does that mean that the particle hitting a photo detector does not collapse until 20 years later when the data is checked by a human?
DennisN said:Good point.
I know that my previous post gave the impression that I believe that a conscious observer is necessary to collapse the probability wave, but that is actually not the case. My own personal opinion, (and that's all that it is) is that a conscious observer is not necessary to collapse the probability wave. Indeed my view is much in line with what bhobba proposed, that "An observation is anything capable of leaving a mark here in the common sense macro world." I believe that so long as the information about which state a particle is in exists anywhere, then the particle will absolutely be in that state. Simply put, if the information exists, then the state exists.meBigGuy said:Does that mean that the particle hitting a photo detector does not collapse until 20 years later when the data is checked by a human?
Fiziqs said:I know that my previous post gave the impression that I believe that a conscious observer is necessary to collapse the probability wave, but that is actually not the case. My own personal opinion, (and that's all that it is) is that a conscious observer is not necessary to collapse the probability. Indeed my view is [...]
Fiziqs said:The OP was looking for a yes or no answer. But there isn't a yes or no answer. To claim otherwise wouldn't be completely honest. And we all want to be completely honest, right?
Fiziqs said:The OP was looking for a yes or no answer. But there isn't a yes or no answer. To claim otherwise wouldn't be completely honest. And we all want to be completely honest, right?
It's good that we're somewhat in agreement as to the necessity of a conscious observer, but I don't believe that I'm as steadfastly against the idea as others may be. It would help if I had a clearer understanding of what exactly constitutes an observer.bhobba said:There is a definite no answer is the sense QM requires a conscious observer - it doesn't.
meBigGuy said:Does that mean that the particle hitting a photo detector does not collapse until 20 years later when the data is checked by a human?
Fiziqs said:It may well be that an environment is capable of causing the collapse only when that environment contains a conscious observer.
Fiziqs said:Until then it is perfectly reasonable to argue that a conscious observer is indeed necessary, at least indirectly.
Possible - well, with a considerable grain of salt. But is it probable? Well, that's certainly up for debate. Extraordinary claims require extraordinary evidence. I also personally like to apply the tools in Carl Sagan's so-called Baloney Detection Kit;Fiziqs said:Until you rule it out, even the outrageous is possible.
Baloney Detection Kit said:Among the tools:
- Wherever possible there must be independent confirmation of the "facts".
- Encourage substantive debate on the evidence by knowledgeable proponents of all points of view.
- Arguments from authority carry little weight -- "authorities" have made mistakes in the past. They will do so again in the future. Perhaps a better way to say it is that in science there are no authorities; at most, there are experts.
- Spin more than one hypothesis. If there's something to be explained, think of all the different ways in which it could be explained. Then think of tests by which you might systematically disprove each of the alternatives. What survives, the hypothesis that resists disproof in this Darwinian selection among "multiple working hypotheses," has a much better chance of being the right answer than if you had simply run with the first idea that caught your fancy.
- Try not to get overly attached to a hypothesis just because it's yours. It's only a way station in the pursuit of knowledge. Ask yourself why you like the idea. Compare it fairly with the alternatives. See if you can find reasons for rejecting it. If you don't, others will.
- Quantify. If whatever it is you're explaining has some measure, some numerical quantity attached to it, you'll be much better able to discriminate among competing hypotheses. What is vague and qualitative is open to many explanations. Of course there are the truths to be sought in the many qualitative issues we are obliged to confront, but finding them is more challenging.
- If there's a chain of argument, every link in the chain must work (including the premise) -- not just most of them.
- Occam's Razor. This convenient rule-of-thumb urges us when faced with two hypotheses that explain the data equally well to choose the simpler.
- Always ask whether the hypothesis can be, at least in principle, falsified. Propositions that are untestable, unfalsifiable are not worth much. Consider the grand idea that our Universe and everything in it is just an elementary particle -- an electron, say -- in a much bigger Cosmos. But if we can never acquire information from outside our Universe, is not the idea incapable of disproof? You must be able to check assertions out. Inveterate skeptics must be given the chance to follow your reasoning, to duplicate your experiments and see if they get the same result.
StevieTNZ said:Could be the case.
Fiziqs said:if we put a detector at the slits, such that it measures which slit the particle went through, but we don't attach this detector to any type of data storage device, then the interference pattern will remain.
Fiziqs said:Until you rule it out, even the outrageous is possible.
meBigGuy said:My personal view is that collapse is a relative view (relational) and that things are as defined as they need to be (relative to other things) to properly correlate. I haven't gotten to decoherence in the susskind lectures yet, so maybe that will change my mind.
meBigGuy said:That doesn't say anything about what could be significant lengths of time during which observers
StevieTNZ said:I personally subscribe to the consciousness 'causes collapse' view, and agree that decoherence is nowhere near to solving the measurement problem.
Yes, I think so too.bhobba said:Best I think to point to good literature on it an get people to make up their own mind.
I must politely disagree with this statement. Although the way that you have phrased it does make it technically correct, but it is not the situation that I was attempting to describe. Specifically, in the highlighted sentence you essentially described turning the environment into a storage device. A particle detector that clicks or flashes, obviously has the potential to leak information into the environment. Making the environment the storage device. But if our detector does not leak information into the environment, then it will of its own accord be unable to introduce decoherence.bhobba said:No - it goes away ie regardless of if it is connected to a storage device or not the interference pattern disappears. An observer, detector or whatever you want to call it, is anything capable of leaving a mark here in the macro world. If its a particle detector it will click or flash.
Fiziqs said:I realize that you disagree with this point of view, but it's not at all bizarre or any more speculative than any other interpretation.
Fiziqs said:It may well be that a system must always contain a conscience observer for decoherence to occur. Not that the conscious observer must be actively involved in the observation, but that it must at least be a part of the system.
DennisN said:I would not even start to go down that path without a proper definition of conscious observer. So, what is your definition of a "conscious observer"?
ktx49 said:I'd define consciousness as the attachment of subjective experience/"feelings" while processing information...however I still don't think its relevant for this discussion. just because we are limited to seeing the world through our consciousness doesn't mean its fundamental to physical processes.
meBigGuy said:All this consciouness stuff arises out of misconception that consciouness arises out of something more than chemical (biological) complexity.
bhobba said:Like I have mentioned a number of times in relation to this issue, Wigner, when he heard about some the early work on decoherence by Zurek, realized the reasons for consciousness causes collapse was no longer required and abandoned it.
Thanks
Bill
StevieTNZ said:Surely Wigner was aware decoherence doesn't solve the measurement problem, so abandoning his, what I call, excellent idea, wasn't required.
I refer you to physicist Stephen Barr's book "Modern Physics ad Ancient Faith" pages 240-241.
kostas230 said:I'm studying quantum mechanics and I can't seem to understand what qualifies as an observer. Does the "observer" need to be a conscious one? Yes or no and why? Thanks in advance :)