Talk:Schrödinger's cat/Archive 1

message: A majority of galaxies have black holes in their centers, but some do not.  So, for any particular galaxy it can go either way.  It might have a black hole in its center; it might not.
And notice that six billion years ago is comfortably before the birth of our solar system.  We were just a nebulous collection of gas at that point.  
And the light from that galaxy has been traveling toward us for the past six billion years.  So, are you saying that it’s in some kind of flux, and is only firmed up by our observing it???  That it both has a black hole and does not have a black hole, both simultaneously, until we observe it and then we make one possibility or the other definite, which I suppose is then transmitted back to the galaxy (instantaneously?).  
To me, the Copenhagen interpretation is absolutely preposterous, and seems one of the least likely interpretations of quantum physics.
Go with a multiverse, a continuously branching set of universes.  As way out as this may be, it’s much more reasonable than the Copenhagen interpretation.  And it also gives an explanation for the two-slit experiment (interference from recently-branched universes).
Or, go with an irreducible degree of probability.  Electrons really are smeared.  Larger particles are also smeared, even macro-particles are, simply to a lesser extent.  God does play dice with the universe so to speak.  And as Niels once famously said to Albert, “Quit telling God what to do!”  Now, I imagine that you have at times read that there was a large element of luck in the evolution of life on Earth and in the particular course that life has taken, that if we rewound the clock and ever-so-slightly reshuffled the deck, we’d most probably get a very different result (the Cambrian explosion might have happened much later, or earlier, or not at all; and many, many other things might have gone in very different directions).  Now, the interesting part is that we might not have to ever-so-slightly reshuffle the deck.  If we merely rewound the clock and let it start from the exact same starting position, there might be enough probability built into particles and velocities that we still might get a very different result.  Once again, I consider this a far more reasonable possibility than the Copenhagen interpretation.  (I like Niels Bohr, but I just think he’s as mistaken as he can be on this one.  And I thank him for communicating clearly.  It’s not like him and Erwin Schrodinger are trying to smuggle concepts in.  They are trying to lay it on the table as clearly as they can.)   FriendlyRiverOtter 21:48, 5 May 2007 (UTC)
thread_title:  Observing a galaxy six billion light years away 

message: Its point is to say, Okay, you think you understand the Copenhagan interpretation . . .
And we can make it even harder.  Let’s have the cat-killing machine turn off after our hour.  Either the radioactive nucleus has decayed or it has not decayed, 50-50 chance, at the end of the first hour.  Now, a separate timer turns off the machine, the box stays closed another hour, with plenty of air, and water and even some nice cat food.  Now, it seems “obvious” to us that for that second hour, the cat is either dead the entire second hour or alive the entire second hour.  But no, it’s both states co-existing at once.  
The point of the example is to shake us up.
As Niels Bohr said, "Anyone who is not dizzy after his first acquaintance with the quantum of action has not understood a word"  .   FriendlyRiverOtter 22:38, 16 April 2007 (UTC)
thread_title:  Schrodinger’s Cat is the beginning of a conversation 

message: “In 1924 a young French graduate student, Louis V. de Broglie, presented his doctoral thesis, in which he argued that all matter, as well as light, demonstrated both particle-like and wave-like properties, and that the heavier a particle was, the more subtle were its wave-like properties.” from DARK COSMOS: IN SEARCH OF OUR UNIVERSE’S MISSING MASS AND ENERGY, Dan Hooper, HarperCollins, 2006, p. 49  
So, a tennis ball will have a very, very, very slight wave-like property, much too slight to measure.  But an electron will have enough of a wave-like property that we can measure it.  The electron will appear as slightly smeared, which in the real world it kind of is, as non-intuitive as that may be.  FriendlyRiverOtter 22:23, 11 April 2007 (UTC)
thread_title:  Everything is a wavicle (Louis de Broglie, 1924) 

message: The geiger counter did the measurement, hence it was the observer. There's no paradox.
--Deng,siyi 01:23, 18 November 2006 (UTC)
thread_title:  NO PARADOX HERE 

message: Superposition of states and mixed states refer to different things; the article seems to confuse them. An electron can be in a pure state; For example, in the position representation, the electron is regarded as being in superposition of classical states. A mixed state is the (limit of) a convex combination of pure states.CSTAR 23:57, 14 Nov 2004 (UTC)
thread_title:  Terminology 

message: It seems to me that more consideration of decoherence in this article needs to be made. The article briefly mentions quantum decoherence, but I believe decoherence is critical to a (modern) understanding of the paradox. The suggested interpretations are: copenhagen, many-worlds, and consistent histories. However, they are described using the same language that was used >40 years ago to describe the conceptual difficulties. In the last 20 years, decoherence has solved alot of these problems. There are still conceptual difficulties, but the way this article is written ignores what has been discovered more recently (see also measurement problem).
Specifically, decoherence shows that a quantum system in a superposition will tend to decohere if it becomes entangle with an environment. That is, by becoming entangled with a large number of external degrees of freedom (which can occur due to air molecules colliding with the system, or even by emitting/absorbing photons in the sense of thermal radiation), a system's constituents tend to fall out of phase with each other. Superpositions only persist because of the phase relationship between the states. As the phase relationship becomes scrambled by interaction with the environment, the superposition is destroyed and is replaced with what looks exactly like a mixed state. Only classical-like states remain stable despite decoherence (a process called Einselection). That is, quantum correlations are replaced with correlations that are indistinguishable from classical correlations. It turns out (based on calculations and even recent experiments) that decoherence occurs very quickly for macroscopic systems. A typical macroscopic system (like a cat) that is found in a superposition will decohere in a ridiculously short time. Only very small and isolated systems (like an electron, etc.) can maintain these superpositions for very long. In a recent experiment, a beam of buckyballs was fired through a grating. An interference pattern was formed at a distant detector, demonstrating the usual quantum interference phenomenon. As the buckyball beam was made hotter, the interference pattern disappeared, because the superposition was being destroyed via decoherence. Hot buckyballs emit lots of thermal photons, which get entangled with the environment, and disrupt the superposition.
What does this have to do with the Schrodinger cat thought experiment? Well I think modern physics has resolved many aspects of it satisfactorily... to the point that the copenhagen interpretation is not needed (at least not how it is written in the current version of the article). For instance, decoherence shows that the cat is certainly not in a superposition: it would decohere very quickly... whereas the nucleus almost certainly is (until it's superposition becomes entangle with the environment, like the detector or whatever). Decoherence establishes a rigorous explanation of when the 'wave function collapse' really occurs, and elegantly proves that the cat is never in a quantum superposition... it exists in a classical mixed state (i.e.: we don't know if it is alive or dead, but it exists in one of these states).
I could update the article myself, but this is a delicate topic (and I'm no expert really). If anyone would like to make some adjustments or comments, that'd be great. Otherwise I'll try to make some changes and see what people think. Comments? Kebes 18:33, 25 May 2005 (UTC)
thread_title:  Decoherence 

message: In a version of the experiment (mysteriously missing from the article), the paradox poses a paradox for the standard interpretation of relativity as well.. Consider:
A cat places a physicist (Dr. Socks) in box #1 and Dr. Socks colleague, (Prof. Furball) in box #2. Each box is equipt with a closed can of poisoned catnip, connected to an electric can opener, triggerable by the entry of a spin up particle. The boxes are closed. The cat operates a device which creates an electron/positron pair from energy. The energy-matter conversion device (an Anti-A-Bomb?) is aligned so that the newly created particles are directed toward the can opener sensors in each box. 
Immediately after detonation of the anti-A bomb, each physicist is in a mixed dead/live state. The cat is then offered the opportunity to open door #1, door #2 or to accept the refrigerator and vacation in Niagara Falls. After gaining approval from the Feline Association for the Prevention of Cruelty to Academics, he opens door #1 and Dr. Socks' wave function promptly collapses. 
But there is more: simultaneously (that is without any delay for information to be transmitted between the boxes at some speed not exceeding c) Professor Furball experiences a queasy feeling and finally knows that that he is ....
--Philopedia 23:57, 26 September 2005 (UTC)
thread_title:  Variation: Problem with Relativity as Well 

message: Though I think this greatly improved the article, I think "macroscopic wavefunction" is an oxymoron.
David R. Ingham 19:05, 26 October 2005 (UTC)
thread_title:  "That said" paragraph at the end of "Copenhagen interpretation" section. 

message: This topic was forked out of this one, it should not come back. See above. DV8 2XL 23:45, 22 November 2005 (UTC)
thread_title:  merge 

message: According to the Feynman Lectures Erwin Schrödinger was one of very few who accepted quantum mechanics.  So he was not seeing any weakness in the theory he had formulated.
The problem is that, rather than accept qm as the only reality, as he did, others were treating classical physics as though it were an exact description of some systems or objects.  This led to the, then workable, but absurd treatment of measurement as a special case.  David R. Ingham 21:01, 20 January 2006 (UTC)
thread_title:  What Schrödinger thought 

message: It is a serious failure of ordinary language that it has so much difficulty describing quantum mechanics.  Since the world is quantum mechanical, this means that what we talk about is, at least on an atomic scale, different from physical reality.
This is not a failure of philosophy and logic, because they are the foundation of the mathematics in which quantum mechanics is formulated.  (See Bertrand Russell for example.)  Of course, everything must be a failure of some philosophy, but even though quantum computer logic will differ from ordinary logic, it is describable in those terms.
makes a common mistake about the exact subject that Schrödinger was illustrating with his cat, but it makes a very important point about the difference between ordinary language and mathematical physics.  This is that homeostasis simplifies the world of life by its negative feedback.  This occurs on many levels, cellular, individual, social, etc.  This helps to explain why language developed in a very different way than would make it easy to talk about quantum physics.  David R. Ingham 04:02, 22 January 2006 (UTC)
thread_title:  "thought in term of mathematics" 

message: About a year ago I made a rushed effort to add a diagram to this article, with the intentions to revise it later:
Well I forgot, until today. I was browsing a forum, and some guy had the username "Schroedingers Cat." His avatar was actually cropped from the image I had made! I think the new one is a lot better:
Be sure to comment on my talk page if you think I should change it, because I still have all the source images.
--Comrade009 21:19, 5 February 2006 (UTC)
replies: text: The new picture is pretty awesome. If it were on a t-shirt or something I'd totally buy it. Kudos to you sir, and kudos again --Katt 10:30, 25 March 2007 (UTC)
thread_title:  New Image 

message: "One view is that Schrödinger intended this thought experiment to indicate that the dead-alive cat would actually exist.  Another is that rather he considered the quantum mechanical theory to be incomplete and not representative of reality in this case:  "Since a cat clearly must either be alive or dead (there is no state between alive and dead, e.g. half-dead) surely the same must be true of the nucleus. It must be either decayed or not decayed."  Whatever Schrödinger thought, the question of when measurement occurs remains an active area of research."
Previous version:
"One view is that Schrödinger intended this thought experiment to indicate that he believed that the dead-alive cat would actually exist. Another is that rather he considered the quantum mechanical theory to be incomplete and not representative of reality in this case: "Since a cat clearly must either be alive or dead (there is no state between alive and dead, e.g. half-dead) surely the same must be true of the nucleus. It must be either decayed or not decayed." Actually Schrödinger thought in term of mathematics rather than ordinary language, so whatever he thought cannot easily be described in ordinary language."
"One view is that Schrödinger intended this thought experiment to indicate that the dead-alive cat would actually exist."  I don't think anyone thinks he thought exactly that.
"Another is that rather he considered the quantum mechanical theory to be incomplete and not representative of reality in this case"  unlikely, considering that he had recently formulated it himself.
"Since a cat clearly must either be alive or dead (there is no state between alive and dead, e.g. half-dead) surely the same must be true of the nucleus."  What about Terri Schiabo?
:Schiavo's body was alive- vegetable state or no, machines or no.  She was alive, and then she was dead.  There is still no state between the two that anyone knows of.  And don't even mention zombies. 82.93.133.130 09:56, 22 November 2006 (UTC)
thread_title:  Controversial pagagraph 

message: I am quite sure I checked last night that I had reverted to the original lightly humorous link and not to the disgusting replacement.  I don't understand what happened.  Trying again to fix it.  David R. Ingham 22:03, 26 February 2006 (UTC)
thread_title:  Vandalism of gedanken toy 

message: I don't see how a thought experiment can have "Practical applications".  These seem to belong to the quantum mechanics page, or to some other page related to it, perhaps entanglement.  The thought experiment has contributed to many applications, but only through a better general understanding of physics.  David R. Ingham 23:36, 26 February 2006 (UTC)
thread_title:  Practical applications section 

message: Some of that seems to be reverting vandalism and some legitimate disagreement.  I thought I had fixed some of that.  Do the vandals have methods that we do not yet understand?  David R. Ingham 05:51, 27 February 2006 (UTC)
thread_title:  vandalism and 03:08, 27 February 2006 Mako098765 (rv obvious; remove uncited) 

message: This edit seems to have unintentionally reverted vandalism.  David R. Ingham 08:15, 27 February 2006 (UTC)
thread_title:  http://en.wikipedia.org/w/index.php?title=Schrödinger%27s_cat&diff=41436104&oldid=41435612 

message: Just a heads-up: In the midst of comments on slashdot someone suggested coming to this article and vandalizing it. —Wrathchild (talk) 18:26, 1 March 2006 (UTC)
replies: text: That anon's edit summary makes sense now. - mako 19:08, 2 March 2006 (UTC)
thread_title:  Slashdotted 

message: If the Judeo-Christian-Mulim god has total knowledge and computing power, "He" must know everything about the cat (as well as having decided when Schrödinger was to formulate the theory).  His computer is not limited by such considerations as the size of atoms or the speed of light, because "He" can alter the laws of physics (if not of logic) at will.  "He" knows the cat's entire wave function, and therefore all that there is about the cat.  (If there were hidden variables they also would not be hidden from "Him".)  So whether the cat is dead or alive, to the extent that that is an meaningful description of the cat, is contained in the wave function and known to "God".  David R. Ingham 06:47, 12 March 2006 (UTC)
replies: text:  You forgot you're using logic to make such statements, and as we said, even the rules of logic are flexible. The one religion you have to "know" is that "you don't know", you cannot assume any certainty in anything you know. It's a humble religion, where you're thankful for any little bit you know, or you think you know, feel like you know, feel like it's revealed to you, but it's in direct opposition with any other ultimate-truth-and-certainty faith-based religions. I only have faith in the limits of my capabilities, in the limits of my power. Everything else is debatable, even logical rules. Whether there are omnipotent beings without limits in their capability including modifying the Laws of Nature and the Laws of Logic, "I don't know." I really don't, and I have a hunch you don't either. Sillybilly 12:21, 18 November 2006 (UTC)
thread_title:  God's cat, or God's Schrödinger, if you prefer (LOL) 

message: Put a dead cat in the box & reverse time.
Penrose suggested that only two phenomena in physics display a direction of time... 2nd Law of Thermodynamics & Wavefunction collapse.
2nd Law of Thermodynamics requires a closed system...
Physics does not discuss Life? --Cave Draco 00:34, 23 June 2006 (UTC)
replies: text: The closed system thing is a red herring; it's easy to apply the 2nd Law to open systems by recasting it as a continuity equation.  Same with the 1st Law.  But Penrose is right, collapse and the 2nd Law are irreversible.  --Michael C. Price talk 00:49, 23 June 2006 (UTC)
thread_title:  Schrödinger's cat & Life 

message: Shouldn't this be in category :Category:Fictional cats? It's clearly a cat, and clearly fictional. JIP | Talk 15:43, 27 August 2006 (UTC)
replies: text: It's a thought experiment.  --Michael C. Price talk 05:25, 28 August 2006 (UTC)

text: Also because the cat is a macro-sized object expected to follow classical laws??  And its 2 states are to illustrate the quantum version of things, no?  While people know a cat is either dead or alive, the idea of two states existing at the same time is an intriguing idea, and helps lead the novice to the idea of multiple states -- for quantum-sized objects.  (I realise he was not trying to explain QP to the general public, but it can work that way) 82.93.133.130 10:08, 22 November 2006 (UTC)
thread_title:  Category 

message: Just glacing through it, and it would appear that people are using it to promote their non-notable webcomic/other thing.  Could be an idea to check if the links are actually anything useful, rather than blatant self-promotion.  However, I've been wrong before, so I'm reluctant to delete anything in haste (apart from a YTMND link, which was pretty obvious). --Angry Lawyer 11:59, 7 September 2006 (UTC)
replies: text: I'm reluctant to delete anything in haste (apart from a YTMND link, which was pretty obvious). --Angry Lawyer 11:59, 7 September 2006 (UTC)

text: Moved everything to the Schrödinger's cat in fiction article, where a lot of it was already duplicated, and added a  tag to where it was in this article. Virogtheconq 01:49, 27 September 2006 (UTC)
thread_title:  "Related Humour" needs a cleanup 

message: The Weinberg quote shouldn't really be under Copenhagen.  Penrose calls this view "many worlds" in his section 29.2 of The Road to Reality, but it does not much resemble the Many worlds below it or the Many-worlds interpretation Wikipedia article.  Nor does Penrose's description.  David R. Ingham 23:26, 7 September 2006 (UTC)
thread_title:  Organization 

message: OR
Why Highlander is based on the Life of Schrödinger's cat
Most of us would initially agree that from year to year, day to day, we remain the same person. i.e. though we don't contain exactly the same atoms at two separate points in our life we can agree that we are the same person because our consciousness remains. Thus, we don't consider ourselves dead merely because our bodies have removed some of our dead skin cells, stomach cells and brain cells. These were replaced by new ones constructed from new atoms ingested thrice daily more or less. So we're agreeing that it is the continued existence of our consciousness or "self" that defines us as alive. The shed dead cells no longer hold that consciousness and so have no bearing on whether we are alive or dead.
Ok. We take that as a priory. So then to the cat, it never dies. Because in some number of parallel universes there exists a living cat. So as far as the cat can remember: it never dies, the cats that existed in universes where it did die are dead and therefore not part of its continued consciousness. From the cat's frame of reference, it never experiences death (or it never remembers experiencing death). Its consciousness will always exist in a universe where the atom has not decayed and it is not dead. So eventually the cat dies from starvation. Or does it? In universes where a can of Whiskas does not apparate in front of the cat it dies, but to the cat this does not happen as the cat's consciousness only continues to exist in universes where this does happen. To the cat, it never dies from starvation. In fact, to the cat, it never 'dies' at all. in some universe its consciousness will always exist in some form (if the possiblities of Quantum flux are infinite).
Then let's extrapolate this to people; specifically, to me. I flew in a plane the other week. Let's say an aluminium atom in the fuselage of the plane might have decomposed at a certain time that would result in the plane losing cabin pressure and it crashing to the ground. According to Schrödinger, because an atom goes through every possibility in some parallel universe, I died last week. In some parallel universe this post never appears because i never land safely at my destination. In some other universe i died from a Brain aneurism just after finishing that last sentence. To extrapolate into insanity now, every moment, every opportunity for me to die, will in some universes be unsuccessful. And so from my point of view, i will never die. Instead of dying slowly of old age, in some universe i will live to see them invent a cure for ageing and i live forever. The universes where this doesn't happen are arbitrary to that existing consciousness. In some parallel universe my consciousness will always exist in some form. And how can one tell the difference between his universe and another where he died in that plane crash last week? I can't. So, in other alternate universes i will be able to look back and remember this moment decades or centuries from now. According to Schrödinger and his cat, the consciousness that wrote this, me, will never die. it will continue for an infinite amount of time in some form. I will live forever.
And so will you.
-- Qa Plar 01:50, 8 September 2006 (GMT)
See the Quantum suicide thought experiment --Angry Lawyer 07:07, 8 September 2006 (UTC)
replies: text: Naturally the MWI folks, such as moi, regard the MWI as simpler. --Michael C. Price talk 00:52, 16 October 2006 (UTC)
thread_title:  Living Forever 

message: Does anyone think this is a reasonable statement?
The problem with the seeming paradox is that the cats motion does interfere with the decay of the nucleus.  This would be determinist in interpretation, that every particle is in a spatial and temporal correspondence with every other particle -that had been set into motion- in the Universe of that box. The paradox is to include the notion of free-will in such a circumstance. Finally, the mere incomprehensibilty of the simultaneous coexistence of free-will and determinism (in the box) -in other words, the simultaneous states of complete free-will and complete determinism- is unnecessary to resolve, because ultimately, anything short of complete knowlege in a system of finite communication speed will always be receiving late information. So, once the cat comprehends the decay of the the nucleus, a short, finite-time afterward, it is dead; and, that the cat could have done something to change the outcome, but couldn't know what.  
It could've known it was impossible for it to know everything there was to know, in real time, to do something about his circumstance; and known, for all practical purposes, that the outcome was inevitable.  It could, however, hold its breath for a longer period of time and eek out a few more blips on the cosmological time-scale.
In other words, the mere time-idependence of the state vector is the substance of the contradiction, because time exists, and correspondence principles exist, such as histories and entanglement, Schrodinger's Cat Paradox isn't such a paradox afterall it just reflects the state of knowlege at any given moment while apparently random fluctuations in events exist.--Charlesrkiss 05:08, 9 October 2006 (UTC)
replies: text: It's only a thought experiment and Schrodinger does explicitly say that the cat must be sealed apart from the radioactive trigger.  --Michael C. Price talk 17:12, 15 October 2006 (UTC)

text: Then interpret "sealed" as meaning it is isolated by definition.  --Michael C. Price talk 00:50, 16 October 2006 (UTC)
thread_title:  Schrödinger's Cat Paradox Resolved 

message: I have replaced Schrodinger's text of the experment with a longer sourced translation.  It differs from the old version in a few details.  For instance it is clear that Schrodinger was envisaging a radioactive source of many atoms, not just one.  --Michael C. Price talk 17:12, 15 October 2006 (UTC)
thread_title:  Sourced translation 

message: Ok, i know this is probably a stupid question but i will ask it anyway...
if the observation is limited to that of a visual wavelength, would that mean that you would be able to hear the cat both alive and dead at the same time?
so hear the cat as it dies but also hear it alive?
- Andrew Hilmy
:: No. Observation is any measurement or interaction, including sound pressure waves hitting ya ear. You're asking if in the double slit experiment there'd be a "special" kind of measurement that picks up 35% of the electron wave traveling through one slit, 65% through the other, without collapsing the wavefunction. As it is today, we only get to know what's going on after we collapsed the wavefunction by the flashes on the screen behind the double slit, and deduce "what must have happened", using cause-effect relationships. If causality and determinism does not stand 100%, then our deductions backwards in time, this and this is what must have happened for us to get this answer, such deductions may not function well, which is another way explain what's going on. If the world is only 99% deterministic on a small scale, and less so the smaller you go, just like a single die roll, it's random(or random enough for this example, never mind that by knowing the motion of each of its atoms applying kinetic theory of gases and classical physics it would still be deterministic), but when you deal with large numbers, with an aggregate of many small scale things, the averages become deterministic, such as if you're rolling the fair dice 10 gazillion times, you will be fairly deterministically 1/6th of the time rolling a 2. Sillybilly 12:32, 18 November 2006 (UTC)
thread_title:  Quick question.... is this observation limited to sight? 

message: Schrodinger's cat has been mentioned in an episode of "Bugs", season 2 episode 7, titled Schrodinger's Bomb. (First Transmission Date May 25th 1996, BBC1). Can this be mentioned?
:Not sure what Bugs is, but you could probably fill a Bible (with all em ricepaper pages) with references to the cat.  Guess people just really like cats,  and funky German names. 82.93.133.130 10:12, 22 November 2006 (UTC)
thread_title:  Mention in Bugs 

message: Hello; it seems that nowadays, many articles are put in a series on a broader topic, with a summary box on the right. Isn't there a series about quantum physics? This article and many others could be part of it. 219.68.141.35 05:11, 2 December 2006 (UTC)
replies: text: Knowing where to stop might be a problem, since all of fundamental physics since 1925 is quantum physics, i.e. non-classical. --Michael C. Price talk 09:09, 7 December 2006 (UTC)
thread_title:  Quantum series of articles 

message: These images are just excessive. We don't need four images of cats inside boxes. We don't need haphazard collages of cats and radiation detectors that look like they were stitched together in Photoshop within 30 seconds. We don't need HTML code with a blinking "not". We need a clear, schematic diagram that doesn't look like it was stuck together from whatever turned up on Google Images for "cat," "geiger counter" and "cannister". The page at the moment look ridiculous. Maelin (Talk | Contribs) 03:23, 5 December 2006 (UTC)
replies: text: I agree, the images are totally useless, and make the page look like a circus. Which is why I deleted them, only to be reverted by Michael C. Price. I invite Michael to to inform us what these ridiculous cartoons contribute to this article, or I will delete them once more. --151.203.239.219 01:52, 8 December 2006 (UTC)
replies: text: I restored the images because the edit comment was incorrect when it said they didn't add anything.  The final diagram is the most physically instructive since it shows two cats simultaneously coexisting along with a flask that was labelled as radioactive poison, unlike the undeleted remaining image, which (apart from the text) is not clear.  The deletion was not discussed on the talk page, so I restored it likewise without discussion.  And BTW the comment on my talk page saying that I only said "I don't agree" is not correct.  My edit comment said "I don't agree that the extra pictures don't add anything", which I thought was as clear an explanation that was given for the deletion.  --Michael C. Price talk 08:08, 8 December 2006 (UTC)
replies: text: First, I'd like to point out that the deletion of the images was in fact discussed on the talk page. Maelin recommended deletion, and I only deleted images two days later. Anyone who objected could have replied to Maelin's suggestion. Second, I am able to accept your argument that the fourth of the pictures, with the superposition, is the most articulate. Nevertheless, in your revert, you suggest that having all four pictures adds something to the article, and not that I was merely injudicious in selecting which of the four pictures to keep. Do you still believe that? If so, what do all four pictures add over any one of them in particular? Or, would you be fine with keeping just the fourth picture? In my opinion, all four pictures look like shit, and we'd probably be best off without any of them until a serious one comes along. --151.203.239.219 08:40, 8 December 2006 (UTC)
replies: text: First, okay, I missed the earlier discussion and my apologies for that.  Second, I would recommend keeping the 2nd (superior graphic quality) and 4th pictures (superior conceptual clarity), along with the text from the 1st.  If that's okay I'll add some more text for which ever pictures we agree to keep.  Generally, I go along with addage that a picture paints a thousand words and that better pictures are needed -- but let's improve not delete wholesale.  --Michael C. Price talk 08:54, 8 December 2006 (UTC)
replies: text: I disagree entirely. The second picture looks rubbish and it has zero information content. It's not obvious at all what is going on, but it -is- obvious the picture was made with about 3 minutes on Google Images and about 30 seconds in Photoshop. People are going to visit the Schrödinger's cat article looking to understand Schrödinger's cat, not hoping for pictures of cats. And I disagree that the fourth is the best for conveying conceptual information, too. It looks like two cats in a box with some kind of nuclear powered poison squirting machine. The first image is the best for conveying information because it alone shows what the whole thing is about, namely, detecting the decay of a nucleus, and it still looks crap. The rest are entirely superfluous. Maelin (Talk | Contribs) 09:16, 8 December 2006 (UTC)
replies: text: The "zero information content" claim is absurd and makes your posititon difficult to take seriously.  Of course it's not obvious what's going on: that's why I suggest copying/adding text to it/them.  --Michael C. Price talk 09:25, 8 December 2006 (UTC)
replies: text: I think Maelin's point is that the second picture has zero information content over the first picture, and I agree with him on that. It's true that the second cat looks prettier or whatever, but that is not what this article is for. I think the first picture is the only one that has all the requirements: the measurement of a decaying nucleus (absent from fourth picture), poison (absent in the second picture), and a superposition of two cats, even if it is executed rather poorly (absent from the second picture). The fourth picture, even though it does portray the superposition the best, fails to make it clear that there is a measurement going on which is causing the superposition. The fourth picture also fails to live up to the sort of seriousness that I think can reasonably be expected of Wikipedia. The first picture is the best, and the only one I think we should keep, but with the understanding that it still sucks and that a new one is badly needed. --151.203.239.219 09:40, 8 December 2006 (UTC)

text: (edit conflict) The image does not convey any useful information. Schrödinger's cat is not a thought experiment that is concerned with the properties of cats and miscellaneous scientific equipment contained within boxes. It's a thought experiment that is concerned with the theory of quantum mechanics extrapolated to macrocosmic systems. The cat and poison are merely accessories. The picture does nothing to help explain the key idea of the article. Picturing a cat inside a box with some apparatus is neither the core thrust nor the conceptually difficult part of the Schrödinger's cat idea and it is not something that images in this article should be focusing on. Perhaps if no better images were available, this image would be acceptable. But the top image is far superior at conveying the main idea and it renders the Google Images cat with the portable multimeter and metal thermos entirely redundant. Maelin (Talk | Contribs) 09:48, 8 December 2006 (UTC)
replies: text: To address 151.203.239.219's clarification I don't think the relative merits are as clear as suggested.  Schrodinger's text talks about a radioactive sample being watched, not a single nucleus, so the radioactive flask in the 4th picture is a better representation of Schrodinger's original conception.  That it is a nucleus in the 1st picture is only evident because of the text.  And what does the tick and cross signify in the 1st image, that the cat doesn't die?  Since the 4th picture is the only one to illustrate the superposition principle applied to a cat -- which is the essential core concept of the experiment -- I don't think we can afford to lose this image.  The 2nd and 4th images are the only ones that clearly show the cat "penned up in a steel chamber" (and the idea of containment and isolation are also important, to address Maelin's point).  So I don't see any basis for claiming that images 1, 2 & 4 have zero information content over each other.  Perhaps we should start from where we all seem to agree: shall we lose the 3rd image? --Michael C. Price talk 10:04, 8 December 2006 (UTC)
replies: text: If any images are needed (and I do not feel any are), then use one image. More than that is pointless redundancy. As has been said, images are not needed to explain this pretty straight forward thought experiment, but if they were to be used, they should relate to the meaning of the experiment and not the example used to explain it. Schrödinger's statement had nothing whatsoever to do with cats, gas or death. I can understand the reason for a pop culture section or side article, but these drawings are not pop culture - they are just images someone threw together using pictures likely under someone else's copyright without permission on a photo manipulation program. That doesn't help anybody. - Kevingarcia 10:30, 10 December 2006 (UTC)
replies: text: Some people find images helpful, some don't.  That aside, I don't know where you're coming from with the statement "Schrödinger's statement had nothing whatsoever to do with cats, gas or death." --Michael C. Price talk 18:04, 10 December 2006 (UTC)
replies: text: Well, taking a quote directly from the current version of the page, he was talking about a different question all together: "when does the actual quantum state stop being a linear combination of states, each of which resemble different classical states, and instead begin to have a unique classical description?" The whole "cat" thing was an analogy that has little to do with a quantum mechanics problem other than the essential question of what state the subject is in. - Kevingarcia 18:15, 10 December 2006 (UTC)
replies: text: No doubt a valid point, but this article is about Schrödinger's cat. --Michael C. Price talk 19:11, 10 December 2006 (UTC)
replies: text: Imagine if the Sorites paradox article was full of pictures of sand heaps. Imagine if the Ship of Theseus article was full of images of ship building. Sure, an image is useful to help people understand what the thing is talking about, but the cat in the box is not the important bit. Schrödinger wasn't trying to make a point about cats; he was trying to make a point about quantum theory. The cat and the box are merely concrete examples to help people recognise to the main issue, just as the sand heap and the ship are in the articles linked above. People don't need to see several images of cats in boxes. That's not the conceptually difficult part of the thought experiment, and it's not the main point of it either. Maelin (Talk | Contribs) 22:52, 10 December 2006 (UTC)
replies: text: Would those articles be diminished if they were illustrated? --Michael C. Price talk 23:31, 10 December 2006 (UTC)
replies: text: If they had several poor-quality images depicting the same thing, a thing that isn't the important aspect of the topic, then yes, they would be diminished. It reduces the quality of the article. Maelin (Talk | Contribs) 01:17, 11 December 2006 (UTC)
replies: text: I agree with KevinGarcia and Maelin. These are bad and actually potentially confusing images that do not at all clarify the conceptually difficult aspects of this thought experiment. I think the article is better off without any of these pictures than with any of them (and especially all three of them). I think we discussed above the required features that an illustration for this page ought to have. None of these pictures have them all. I think they should all be deleted until someone who is interested produces a picture that actually clarifies this thought experiment. --151.203.239.219 07:40, 11 December 2006 (UTC)
replies: text: Exactly. Bad images detract from the validity of the theoritical argument. Any image is unneeded, but one might be acceptable... none from the current crop. - Kevingarcia 03:53, 12 December 2006 (UTC)

text: Let's leave the pictures in until we find a better set.  Improve, don't delete. As I have explained, the remainining pictures are illustrating different aspects of the experiment. --Michael C. Price talk 08:26, 11 December 2006 (UTC)

text: Yes, that one is much better. Maelin (Talk | Contribs) 10:22, 11 December 2006 (UTC)
replies: text: Good. I suggest replacing the 3rd image with this?  I'm not sure of the mechanism for uploading images -- if someone else could do it, and sort out the permissions side that would be great. --Michael C. Price talk 13:55, 11 December 2006 (UTC)
replies: text: I'd suggest replacing all of them with this. We only need, and should only have, one picture if one picture will convey all the information possible. This picture, when combined with a suitable caption, will show everything that is important about the experiment. Maelin (Talk | Contribs) 00:13, 12 December 2006 (UTC)
replies: text: I agree. We need only one picture that does a good job, and this is the best picture so far. I can only suggest adding a little black and white radioactive sign on the container that activates the lever, but I'm fine without it too. --151.203.14.187 00:25, 12 December 2006 (UTC)
replies: text: At the very least. But don't add anything to the image, the conciet of an image at all is more than enough. - Kevingarcia 03:53, 12 December 2006 (UTC)
replies: text: Since it's not obvious if the Creative Commons licence on the web page (see at bottom) extends to the image itself, I've sent the author a brief e-mail asking if we could use the image, but his automailer tells me he is away until December 19. Assuming it's okay, I will stick a black-and-white nuclear symbol on the image and upload it under the same licence (as required). We can then use it to replace the silly-looking pictures currently there. Maelin (Talk | Contribs) 08:19, 12 December 2006 (UTC)
replies: text: We seem to be okay with respect the to Creative Commons licence, but it can't do any harm to inform him what we plan.  BTW I like the idea of sticking a nuclear symbol to the detector.  --Michael C. Price talk 08:27, 12 December 2006 (UTC)

text: Unfortunately we can't use the good image found above, as it comes from a textbook. Maelin (Talk | Contribs) 05:44, 2 January 2007 (UTC)
replies: text: From a textbook?  It comes from an article by the late Bryce Seligman DeWitt, Quantum Mechanics and Reality, Physics Today,23(9) pp 30-40 (1970) --Michael C. Price talk 09:21, 2 January 2007 (UTC)
replies: text: None of which explains why the current images should remain. They should be removed and kept off. - Kevingarcia 06:42, 6 January 2007 (UTC)
replies: text: They are there because not everyone agrees with your view that all images should be destroyed. --Michael C. Price talk 09:52, 6 January 2007 (UTC)
replies: text: That is a complete straw man argument. Nobody wants all images destroyed, what we want are good, clear and encyclopedic images that add to the article. We don't want cartoony grinning cats and incoherent collages of whatever turned up on Google Imagesearch. Maelin (Talk | Contribs) 01:59, 29 January 2007 (UTC)
replies: text: While you're around, what about my point that the proposed image doesn't come from a textbook and therefore may be admissable?--Michael C. Price talk 02:11, 29 January 2007 (UTC)
replies: text: "Textbook" wasn't my point, my point was that it wasn't the work of the fellow who owned the page, and that we presumably need permission from whoever is the copyright holder. Of course, I'm no copyright lawyer. Maelin (Talk | Contribs) 02:59, 29 January 2007 (UTC)
replies: text: I'm no lawyer either, but it looks to me like the creative commons license does give us permission to copy, modify and use the image.  That the image originates from elsewhere should make it easier, shouldn't it? --Michael C. Price talk 09:27, 29 January 2007 (UTC)
replies: text: I shouldn't think so. Since the author of the article doesn't own the image, his CC licence wouldn't extend to it. Unless we can be sure he got that image legitimately and his article is legally a derivative work, we can't take the image back out of it, as far as I know. Maelin (Talk | Contribs) 11:06, 29 January 2007 (UTC)
thread_title:  Useless images 

message: Yes that would cut it as an explanation but isn't there a simpler explanation than appealing to macroscopic effects?
For those who have it, read Feynman Lectures Vol 3. 3-3: "Scattering From a Crystal". A collapse of the wavefunction occurs if 'in principle' you could measure something.
To cut a long story short: A neutron propagates though a crystal and simultaneously travels through every gap interfering with itself creating a diffraction pattern analagous to the Young Two-Slit, but also creating a diffuse background. This diffuse background corresponds to a collapsing of the wave function. The reason for this collapse lies in the spin of the neutron; the spin state of the neutron will sometimes decide the spin state of an atom in the crystal (conservation of momentum), the spin state of an atom is changed, so nature knows which atom scattered the neutron (it no longer went through every slit). i.e: the crystal itself performed the measurement. Nothing to do with macroscopic decoherence. It wasn't that a person made an observation, but that 'in principle' a person 'could' go back and check the crystal.
In the same way, why cannot the detector collapse the decay state and some lazy scientist come back and check it later? Is half the physics community simply not listening to the other or something? Hate to sound hippy, but doesn't crystals fix everything? -- Rpf 16:21, 6 December 2006 (UTC)
replies: text: You're right, the cat paradox is only a "paradox" to those physicists who have already convinced themselves that wavefunctions don't collapse until a physicist intervenes. --Michael C. Price talk 09:07, 7 December 2006 (UTC)
thread_title:  Who needs decoherence? Feynman's Neutron Scattering from a Crystal 

message: Does the cat not count as an observer? If not, would that mean that as soon as a cat is not being observed by a truly conscious being, it would not actually exist in one particular state? And, could this experiment not be conducted using something which does not live, like an apple, and some sort of 'speed-up-rotting-process-of-apples' poison? Then everytime the experiment is conducted the outcome should be random, as in one time the apple is completely rotten, and the other time it is not. AppleHaven 13:54, 22 January 2007 (UTC)
replies: text: That's not really the point. The whole point of the exercise is to demonstrate that we shouldn't arbitrarily separate microscopic scales from macroscopic ones. Nobody finds the idea of an atom existing in superposition of decayed and not decayed to be particularly troublesome, but we do find the idea of a cat existing in superposition of alive and dead to be somewhat hard to swallow. The thought experiment is supposed to show that we can't have our seemingly-acceptable "small scale" superpositions without necessarily accepting out repulsive "large scale" superpositions. Maelin (Talk | Contribs) 02:40, 23 January 2007 (UTC)
thread_title:  the cat as an observer, and apples 

message: I've heard that the Schrodinger's cat theory is said to be "If you put a cat in a box, there is a 50-50 percent chance of it being DOA (Dead or Alive)." However, the article states otherwise. Clarify? —The preceding unsigned comment was added by The velociraptor (talk • contribs) 23:49, 26 January 2007 (UTC)
replies: text: The purported coclusion is that there is a 100% chance of it being dead AND alive. As explained in the article.1Z 01:50, 27 January 2007 (UTC)
thread_title:  Is there a common misconception? 

message: Animal cruelty aside, any scientists actually done this? Yes, even though I know the state of the cat is in lingo in theory, did anyone try this? —The preceding unsigned comment was added by The velociraptor (talk • contribs) 01:42, 29 January 2007 (UTC)
replies: text: Highly doubtful. It's a thought experiment intended to demonstrate a necessary conclusion of a particular model. No rational scientist would attempt to actually do it, because there is nothing that could be learned. Maelin (Talk | Contribs) 01:55, 29 January 2007 (UTC)
thread_title:  Has anyone actually tried this experiment in real life? 

message: Does anyone know what the name of Schroedinger's Cat actually was?
I've read a lot of papers on the theory and done a lot of searching, but I've never been able to find the answer to this question. —The preceding unsigned comment was added by 71.229.241.19 (talk) 11:01, 16 February 2007 (UTC)
replies: text: I assume you mean the cat in the eponymous thought experiment. As far as I know it never had a name, since it was merely hypothetical. Otherwise, you could mean the cat that Erwin Schrodinger actually owned, which he presumably kept well-fed in his house. If he even owned a cat, I strongly doubt its name would appear in any scientific papers. Maybe a biography. Maelin (Talk | Contribs) 12:59, 16 February 2007 (UTC)
thread_title:  Name of Schroedinger's Cat 

message: "The experiment is a purely theoretical one, and the machine proposed is not known to have been constructed." Duh!
I think the point that is often missed with this though experiment is that the "catbox" would have to be essentially a black hole. In order to completely isolate the internal environment from the outside to prevent de-coherence, space time would have to be massively warped in a sphere around the cat preventing information from leaving or penetrating the perimeter of the "catbox". Such a tremendous spherical space/time warping would probably have to be generated internally and result in the internal environment advancing to infinite time just at the instant communication of with the "outside" universe ceases. Of course, such a device would have to generate and magnify gravity (particle/waves) from an internal energy source; however, no one has yet to convert electrons or photons to gravitons much less a device for generating artificial gravity and focusing it. But, who knows: if the universities import more visa workers working on important research topics such as "how many quantum strings can dance on the head of a pin", the wages of physicists might be driven so low that they will have to invent it or go to work at McDonalds! Does McDonald's make their burger flippers sign non-disclosure agreements? Maybe God does shoot craps, modern physics is God's practical joke on sentient creation and the universe is laughing at you behind your back!
—Preceding unsigned comment added by 71.36.187.39  (talk • contribs) 
:But that's the point of thought experiments, you posit what may be possible and ignore technical details of implementation. --Michael C. Price talk 13:49, 16 March 2007 (UTC)
replies: text: Further it might be worth pointing out in the article that it is not necessary to completely isolate the experiment from the environment: decoherence is not an all or nothing thing.  All that is required is that the energy exchanged with the environment be << kT. --Michael C. Price talk 14:03, 16 March 2007 (UTC)
thread_title:  Cat in the Black Hole 

message: I am going to edit down this section. There is far too much OR, under-sourced, confusing material.
To start with:
Though very recent developments show exactly the contrary, namely that measurements by a mesoscopic apparatus does NOT immediately alter the quantum state of the phenomenon, and the alteration happens only progressively, when the "fine-control" on the mesoscopic system is lost. See for instance http://www.qis-jst.on.arena.ne.jp/kochi/poster/abst/11.pdf. This proves the Copenhagen interpretation does not work at least up to the mesoscopic (thousands of atoms, or so) size.
The reference is only to an abstract. a proper reference would be needed to demonstrate the point. In any case, this is too specific and not notable enough for an overview article. (The copenhagen interpretation page might be more appropriate).
1Z 17:31, 23 March 2007 (UTC)
thread_title:  Copenhagen interpretation 

message: "However, it is hard to maintain the view that superpositions never occur in view of single-particle (e.g Young's slits) experiments and quantum computing. No framework but superposition can explain why these phenomena exist at all.[4]. If they admit that there is such a phenomenon as superposition, the proponents of the Ensemble interpretation are left without any response to the challenge of the paradox: how and whether collapse occurs. On the other hand, if superposition is denied, then quantum computing, etc, becomes incomprehensible.[5]."
I removed the above as it is incorrect. The Quantum Ensemble Interpretation is mathematically identical to the CI.
Dr. Leslie Ballentine (Quantum mechanics: A Modern development, text book) has assured me in emails that the EI is compatible with Quantum Computing, 
User:Kevin aylward
All interpretations are are mathematically compatible with each other. The EI does not explain what is happening in single-particle experiments (and is fairly explicit about the fact).
If you have citations. please insert them into the article. Wikipedia is based on reporting both sides of 
a controversy. You may not remove "incorrect" material without providing a verifiable source.
1Z 18:39, 17 April 2007 (UTC)
thread_title:  Ensemble Interpretation 

message: The one paper cited in the "Experimental results" section appears to be unpublished, which would mean it should not be cited by Wikipedia.  Am I missing something?  Has the paper actually been published?  --Allen 18:45, 12 May 2007 (UTC)
replies: text: Okay, but for now I'm removing the section, quoted below.  I'm not an expert, so I can't judge for sure, but much of this section seems fishy.  Some of it seems like it might be correct but lacks sourcing and is probably redundant with other parts of the article.  Other parts of this section seem like original thought, others still like POV, and a few I suspect are simply incorrect.  The one reference given, as I noted above, is to an unpublished paper and therefore cannot be used here.  --Allen 04:03, 17 May 2007 (UTC)
replies: text: There are mesoscopic experiments which give direct insights into SC: however, no editor has so far managed to cite one properly. 1Z 12:50, 17 May 2007 (UTC)
thread_title:  unpublished paper? 

message: That is what Dan Hooper says:
“The truth is that every experimental prediction that you could ever make using the Copenhagen interpretation is exactly identical to the prediction you would make using the many-worlds interpretation.  Because physics is fundamentally an experimental science, with competing theories judged on the merit of their agreement with experimental tests, there is no scientific way of deciding which interpretation is correct.  I would go as far as to say that it is not even scientific to suggest that one interpretation is more correct than any other.  All the same, it would be hard to find a subject that more physicists love to talk about, especially over a few pints of beer.”
from DARK COSMOS: IN SEARCH OF OUR UNIVERSE’S MISSING MASS AND ENERGY, Dan Hooper, HarperCollins, 2006, p. 58.  [The page number was previously given as ten pages later, the correct page number is 58.]
However, we still have the familiar situation with the electron, you can know either position or velocity, but not both.  Is that because the experiment is hitting the electron with additional photons in order to observe it, or are we simply observing the photons that would have hit it anyway?   FriendlyRiverOtter 06:13, 27 May 2007 (UTC)
replies: text: Please don't use this page for discussing Schrödinger's cat; talk pages are meant for discussing the article and improvements to the article, not discussing the subject of the article. Ask such questions at the reference desk instead. --Philosophus T 09:27, 27 May 2007 (UTC)
thread_title:  All interpretations, including Copenhagen, take one step beyond current science? 

message: Following is an abstract from a Harvard site that might get us started (we still need to put it in plain English!):
:"Bohmian mechanics and the Ghirardi-Rimini-Weber theory provide opposite resolutions of the quantum measurement problem: the former postulates additional variables (the particle positions) besides the wave function, whereas the latter implements spontaneous collapses of the wave function by a nonlinear and stochastic modification of Schrodinger's equation. Still, both theories, when understood appropriately, share the following structure: They are ultimately not about wave functions but about "matter" moving in space, represented by either particle trajectories, fields on space-time, or a discrete set of space-time points. The role of the wave function then is to govern the motion of the matter."     FriendlyRiverOtter 07:29, 18 June 2007 (UTC)
thread_title: Ghirardi-Rimini-Weber