[math-fun] NYTimes: quantum theory w/o observers
Quite a discussion going on here: "to quote the physicist J.S. Bell: "It would seem that the theory is exclusively concerned about Âresults of measurement, and has nothing to say about anything else. What exactly qualifies some physical systems to play the role of ÂmeasurerÂ? Was the wavefunction of the world waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer, for some better qualified system  *** with a Ph.D.? **** If the theory is to apply to anything but highly idealized laboratory operations, are we not obliged to admit that more or less Âmeasurement-like processes are going on more or less all the time, more or less everywhere. (ÂAgainst ÂMeasurement Â)" http://opinionator.blogs.nytimes.com/2013/07/25/return-of-the-stingy-oddsmak...
On 26 Jul 2013 at 6:17, Henry Baker wrote:
Quite a discussion going on here:
By "here" I guess you mean in the NYTimes.. Thanks for the pointer.. I've always wondered this same thing. I don't understand QM, really, but I've wondered things like if the "first observer" collapses the wave, can you tell if you're a 'second observer" or not and you only *think* you collapsed the wave...
"to quote the physicist J.S. Bell:
... Was the wavefunction of the world waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer, for some better qualified system ... *** with a Ph.D.?
And if you're not earth-centric, perhaps the wave function for the whole universed was collapsed by a being a zillion light-years away a billion years ago... Thanks for the ptr!! /bernie\ -- Bernie Cosell Fantasy Farm Fibers mailto:bernie@fantasyfarm.com Pearisburg, VA --> Too many people, too few sheep <--
In this context doesn't "observer" really mean "anything that would allow observation if someone looked" rather than someone actually looking....though without actually looking how you'd tell if there was still an effect I have no idea. On 26 Jul 2013, at 15:23, Bernie Cosell wrote:
On 26 Jul 2013 at 6:17, Henry Baker wrote:
Quite a discussion going on here:
By "here" I guess you mean in the NYTimes.. Thanks for the pointer.. I've always wondered this same thing. I don't understand QM, really, but I've wondered things like if the "first observer" collapses the wave, can you tell if you're a 'second observer" or not and you only *think* you collapsed the wave...
"to quote the physicist J.S. Bell:
... Was the wavefunction of the world waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer, for some better qualified system ... *** with a Ph.D.?
And if you're not earth-centric, perhaps the wave function for the whole universed was collapsed by a being a zillion light-years away a billion years ago...
Thanks for the ptr!! /bernie\
-- Bernie Cosell Fantasy Farm Fibers mailto:bernie@fantasyfarm.com Pearisburg, VA --> Too many people, too few sheep <--
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The meaning and purpose of life is to give life purpose and meaning. The instigation of violence indicates a lack of spirituality.
Callender, who wrote the NYT piece, already alluded to the "real" resolution of the "who counts as an observer" pseudo-paradox: What happens when you observe a system is that you are now *part of* the system. To someone outside, who has not yet observed, you yourself are in a state of quantum superposition based on what observation you made. --Michael On Fri, Jul 26, 2013 at 10:37 AM, David Makin <makinmagic@tiscali.co.uk>wrote:
In this context doesn't "observer" really mean "anything that would allow observation if someone looked" rather than someone actually looking....though without actually looking how you'd tell if there was still an effect I have no idea.
On 26 Jul 2013, at 15:23, Bernie Cosell wrote:
On 26 Jul 2013 at 6:17, Henry Baker wrote:
Quite a discussion going on here:
By "here" I guess you mean in the NYTimes.. Thanks for the pointer.. I've always wondered this same thing. I don't understand QM, really, but I've wondered things like if the "first observer" collapses the wave, can you tell if you're a 'second observer" or not and you only *think* you collapsed the wave...
"to quote the physicist J.S. Bell:
... Was the wavefunction of the world waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer, for some better qualified system ... *** with a Ph.D.?
And if you're not earth-centric, perhaps the wave function for the whole universed was collapsed by a being a zillion light-years away a billion years ago...
Thanks for the ptr!! /bernie\
-- Bernie Cosell Fantasy Farm Fibers mailto:bernie@fantasyfarm.com Pearisburg, VA --> Too many people, too few sheep <--
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The meaning and purpose of life is to give life purpose and meaning. The instigation of violence indicates a lack of spirituality.
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-- Forewarned is worth an octopus in the bush.
"Measurement" is simply entangling the quantum state under observation with a macroscopic pointer state like a brain. When the pointer state is small enough that it can be kept coherent, one can disentangle the two systems after measurement and have the pointer state "unobserve" the other quantum state. See the quantum eraser experiment---which you can do using a laser pointer, see http://www.sciam.com/slideshow.cfm?id=a-do-it-yourself-quantum-eraser ---and the delayed choice quantum eraser experiment. http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser On Fri, Jul 26, 2013 at 9:07 AM, Michael Kleber <michael.kleber@gmail.com> wrote:
Callender, who wrote the NYT piece, already alluded to the "real" resolution of the "who counts as an observer" pseudo-paradox: What happens when you observe a system is that you are now *part of* the system. To someone outside, who has not yet observed, you yourself are in a state of quantum superposition based on what observation you made.
--Michael
On Fri, Jul 26, 2013 at 10:37 AM, David Makin <makinmagic@tiscali.co.uk>wrote:
In this context doesn't "observer" really mean "anything that would allow observation if someone looked" rather than someone actually looking....though without actually looking how you'd tell if there was still an effect I have no idea.
On 26 Jul 2013, at 15:23, Bernie Cosell wrote:
On 26 Jul 2013 at 6:17, Henry Baker wrote:
Quite a discussion going on here:
By "here" I guess you mean in the NYTimes.. Thanks for the pointer.. I've always wondered this same thing. I don't understand QM, really, but I've wondered things like if the "first observer" collapses the wave, can you tell if you're a 'second observer" or not and you only *think* you collapsed the wave...
"to quote the physicist J.S. Bell:
... Was the wavefunction of the world waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer, for some better qualified system ... *** with a Ph.D.?
And if you're not earth-centric, perhaps the wave function for the whole universed was collapsed by a being a zillion light-years away a billion years ago...
Thanks for the ptr!! /bernie\
-- Bernie Cosell Fantasy Farm Fibers mailto:bernie@fantasyfarm.com Pearisburg, VA --> Too many people, too few sheep <--
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The meaning and purpose of life is to give life purpose and meaning. The instigation of violence indicates a lack of spirituality.
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-- Forewarned is worth an octopus in the bush. _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
-- Mike Stay - metaweta@gmail.com http://www.cs.auckland.ac.nz/~mike http://reperiendi.wordpress.com
I seem to have a mental block against learning even basic QM. But I like Callender's mention that, taking the long view, the observer is not a privileged entity, but just another part of the universe that -- like every part of the universe -- interacts with every part of the universe. --Dan On 2013-07-26, at 10:08 AM, Mike Stay wrote:
"Measurement" is simply entangling the quantum state under observation with a macroscopic pointer state like a brain. When the pointer state is small enough that it can be kept coherent, one can disentangle the two systems after measurement and have the pointer state "unobserve" the other quantum state.
See the quantum eraser experiment---which you can do using a laser pointer, see http://www.sciam.com/slideshow.cfm?id=a-do-it-yourself-quantum-eraser ---and the delayed choice quantum eraser experiment. http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser
On Fri, Jul 26, 2013 at 9:07 AM, Michael Kleber <michael.kleber@gmail.com> wrote:
Callender, who wrote the NYT piece, already alluded to the "real" resolution of the "who counts as an observer" pseudo-paradox: What happens when you observe a system is that you are now *part of* the system. To someone outside, who has not yet observed, you yourself are in a state of quantum superposition based on what observation you made.
--Michael
On Fri, Jul 26, 2013 at 10:37 AM, David Makin <makinmagic@tiscali.co.uk>wrote:
In this context doesn't "observer" really mean "anything that would allow observation if someone looked" rather than someone actually looking....though without actually looking how you'd tell if there was still an effect I have no idea.
. . .
In the discussion following the first Callender article, there was much criticism voiced concerning people lifting "uncertainty" from physics and trying to misapply it out of context. In view of which, it was both amusing and provocative to encounter later the same day in http://terrytao.wordpress.com/2013/07/26/computing-convolutions-of-measures << It is a challenge to make this intuition perfectly rigorous, as one has to somehow deal with the obstruction presented by the Heisenberg uncertainty principle, but it can be made rigorous in various asymptotic regimes, for instance using the machinery of wave front sets (which describes the high frequency limit of the phase space distribution). >> On 7/26/13, Dan Asimov <dasimov@earthlink.net> wrote:
I seem to have a mental block against learning even basic QM.
But I like Callender's mention that, taking the long view, the observer is not a privileged entity, but just another part of the universe that -- like every part of the universe -- interacts with every part of the universe.
--Dan
On 2013-07-26, at 10:08 AM, Mike Stay wrote:
"Measurement" is simply entangling the quantum state under observation with a macroscopic pointer state like a brain. When the pointer state is small enough that it can be kept coherent, one can disentangle the two systems after measurement and have the pointer state "unobserve" the other quantum state.
See the quantum eraser experiment---which you can do using a laser pointer, see http://www.sciam.com/slideshow.cfm?id=a-do-it-yourself-quantum-eraser ---and the delayed choice quantum eraser experiment. http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser
On Fri, Jul 26, 2013 at 9:07 AM, Michael Kleber <michael.kleber@gmail.com> wrote:
Callender, who wrote the NYT piece, already alluded to the "real" resolution of the "who counts as an observer" pseudo-paradox: What happens when you observe a system is that you are now *part of* the system. To someone outside, who has not yet observed, you yourself are in a state of quantum superposition based on what observation you made.
--Michael
On Fri, Jul 26, 2013 at 10:37 AM, David Makin <makinmagic@tiscali.co.uk>wrote:
In this context doesn't "observer" really mean "anything that would allow observation if someone looked" rather than someone actually looking....though without actually looking how you'd tell if there was still an effect I have no idea.
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My point was more relating to the fact that the originally quoted piece seemed to be complaining that some form of "intelligence" was required in order to "observe" when in fact this is not the case. On 26 Jul 2013, at 16:07, Michael Kleber wrote:
Callender, who wrote the NYT piece, already alluded to the "real" resolution of the "who counts as an observer" pseudo-paradox: What happens when you observe a system is that you are now *part of* the system. To someone outside, who has not yet observed, you yourself are in a state of quantum superposition based on what observation you made.
--Michael
On Fri, Jul 26, 2013 at 10:37 AM, David Makin <makinmagic@tiscali.co.uk>wrote:
In this context doesn't "observer" really mean "anything that would allow observation if someone looked" rather than someone actually looking....though without actually looking how you'd tell if there was still an effect I have no idea.
On 26 Jul 2013, at 15:23, Bernie Cosell wrote:
On 26 Jul 2013 at 6:17, Henry Baker wrote:
Quite a discussion going on here:
By "here" I guess you mean in the NYTimes.. Thanks for the pointer.. I've always wondered this same thing. I don't understand QM, really, but I've wondered things like if the "first observer" collapses the wave, can you tell if you're a 'second observer" or not and you only *think* you collapsed the wave...
"to quote the physicist J.S. Bell:
... Was the wavefunction of the world waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer, for some better qualified system ... *** with a Ph.D.?
And if you're not earth-centric, perhaps the wave function for the whole universed was collapsed by a being a zillion light-years away a billion years ago...
Thanks for the ptr!! /bernie\
-- Bernie Cosell Fantasy Farm Fibers mailto:bernie@fantasyfarm.com Pearisburg, VA --> Too many people, too few sheep <--
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The meaning and purpose of life is to give life purpose and meaning. The instigation of violence indicates a lack of spirituality.
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-- Forewarned is worth an octopus in the bush. _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
The meaning and purpose of life is to give life purpose and meaning. The instigation of violence indicates a lack of spirituality.
On 7/26/2013 7:23 AM, Bernie Cosell wrote:
On 26 Jul 2013 at 6:17, Henry Baker wrote:
Quite a discussion going on here: By "here" I guess you mean in the NYTimes.. Thanks for the pointer.. I've always wondered this same thing. I don't understand QM, really, but I've wondered things like if the "first observer" collapses the wave, can you tell if you're a 'second observer" or not and you only *think* you collapsed the wave...
You won't learn anything useful from the NYT discussion (Callendar's essay is good, but it's short and assumes a lot of background). The best current ideas are decoherence and Everett's many worlds. Read Schlosshauer's review papers: http://arxiv.org/pdf/0804.1609v1.pdf or for more depth http://arxiv.org/pdf/quant-ph/0312059.pdf Brent Meeker
"to quote the physicist J.S. Bell:
... Was the wavefunction of the world waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer, for some better qualified system ... *** with a Ph.D.? And if you're not earth-centric, perhaps the wave function for the whole universed was collapsed by a being a zillion light-years away a billion years ago...
Thanks for the ptr!! /bernie\
There's a good paper by Schlosshauer and Camilleri that discusses the historical debate over the Heisenberg cut and how the question has mostly been answered by the idea of decoherence. http://arxiv.org/pdf/0804.1609v1.pdf I say 'mostly' because pushing the Heisenberg cut all the way to include conscious observers, as in Everett's interpretation of QM, is still a little controversial because we lack a good theory of consciousness. Brent Meeker On 7/26/2013 6:17 AM, Henry Baker wrote:
Quite a discussion going on here:
"to quote the physicist J.S. Bell:
"It would seem that the theory is exclusively concerned about “results of measurement,” and has nothing to say about anything else. What exactly qualifies some physical systems to play the role of “measurer”? Was the wavefunction of the world waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer, for some better qualified system … *** with a Ph.D.? **** If the theory is to apply to anything but highly idealized laboratory operations, are we not obliged to admit that more or less “measurement-like” processes are going on more or less all the time, more or less everywhere. (“Against ‘Measurement’ “)"
http://opinionator.blogs.nytimes.com/2013/07/25/return-of-the-stingy-oddsmak...
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On 26/07/2013 18:16, meekerdb wrote:
I say 'mostly' because pushing the Heisenberg cut all the way to include conscious observers, as in Everett's interpretation of QM, is still a little controversial because we lack a good theory of consciousness.
Isn't that rather like saying "assuming that gravitation applies the same way to conscious observers as to everything else is still a little controversial because we lack a good theory of consciousness"? I mean, there isn't actually any good reason to think that conscious observers are treated specially by the universe; it's just a sad historical accident that early speculation about how QM works happened to treat conscious observers (or at least their "measurements") specially. (No doubt the above is "a little controversial" -- but that's not really the same as saying it's likely to be wrong.) -- g
I agree completely... the whole "measurement paradox" comes from historical confusion (to be fair, confusion which was shared by some of its founders). Einstein taught us that we don't get to ask the question "what's happening on Alpha Centauri right now?" It's an intuitive question to want to ask given our everyday experience, but it turns out to be the result of fuzzy thinking: the word "now" just doesn't make sense in this context. Similarly quantum mechanics teaches us that questions like "what would I have observed if I had done a different measurement", or "what is the state really", or (David Deutsch's favorite) "where did the number get factored?" are just not well-defined. The struggle is figuring out which words and concepts taken from our everyday experience still make sense in the quantum world --- which questions we really get to ask. It's true that that's less clear for quantum mechanics than it is for relativity, and it's upsetting to imagine that words like "state" (and "would"!) might be among those that we have to let go of. But I strongly suspect that most of the "paradoxes" that trouble QM will turn out to be in this category. At least that's what I think when I'm in hard-core analytic philosophy mode ;-) Cris On Jul 27, 2013, at 7:34 PM, Gareth McCaughan <gareth.mccaughan@pobox.com> wrote:
I mean, there isn't actually any good reason to think that conscious observers are treated specially by the universe; it's just a sad historical accident that early speculation about how QM works happened to treat conscious observers (or at least their "measurements") specially.
participants (10)
-
Bernie Cosell -
Cris Moore -
Dan Asimov -
David Makin -
Fred Lunnon -
Gareth McCaughan -
Henry Baker -
meekerdb -
Michael Kleber -
Mike Stay