# Schrodinger's Cat **URL:** \ **Category:** Factual Questions\ **Created:** [January 3, 2012, 4:03pm UTC](https://boards.straightdope.com/t/schrodingers-cat/608260 "2012-01-03T16:03:55Z")\ **Posts on this page:** 20\ **Page:** 5
**Author:** ![Apathetic\_Coma](https://avatars.discourse-cdn.com/v4/letter/a/ed8c4c/32.png) [@Apathetic\_Coma](https://boards.straightdope.com/u/Apathetic_Coma)\ **Post date:** [January 5, 2012, 9:03pm UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/81 "2012-01-05T21:03:50Z")
> [@Reno\_Nevada](#): > > The best answer that I have ever read to this question was of course Cecil’s: [The story of Schroedinger’s cat (an epic poem) - The Straight Dope](http://www.straightdope.com/columns/read/113/the-story-of-schroedingers-cat-an-epic-poem) Dude, I was just browsing…but that link made me sign up. Don’t worry, I’m good. :o ---
**Author:** ![Candyman74](https://avatars.discourse-cdn.com/v4/letter/c/ad7895/32.png) [@Candyman74](https://boards.straightdope.com/u/Candyman74)\ **Post date:** [January 6, 2012, 1:51am UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/82 "2012-01-06T01:51:07Z")
Is if just me, or are the usernames whc.03grady and tomh.4040 reminiscent in style of each other? One being “I’ve figured out what’s wrong with quantum theory” and the other being “I’ve figured out that Einstein was wrong about relativity”? ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [January 6, 2012, 7:49am UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/83 "2012-01-06T07:49:26Z")
> [@Candyman74](#): > > Is if just me, or are the usernames whc.03grady and tomh.4040 reminiscent in style of each other? I don’t think so. To me, it seems that **whc.03grady** has shown himself both more knowledgeable and corrigible on his topic, plus we haven’t yet seen any inane thought experiments intended to expose errors in the thinking of some of the smartest people in the world for nearly the past 100 years that can ultimately be reduced to trivial misunderstandings based on biased readings of pop-sci arguments… ---
**Author:** ![canterburyales](https://avatars.discourse-cdn.com/v4/letter/c/ad7895/32.png) [@canterburyales](https://boards.straightdope.com/u/canterburyales)\ **Post date:** [January 6, 2012, 12:58pm UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/84 "2012-01-06T12:58:25Z")
Many posters have recommended researching the topic to get a better understanding of the strangeness of quantum phenomenon that is being illustrated by the story of Schrodinger’s Cat. That is the best approach. I think the heart of the matter is the difficulty in accepting the quantum view that the world seems to be inherently probabilistic. As a non-physicist I have gotten a lot out of the various Feynman lectures available online. This series is a good place to start: > **[Richard Feynman Video - The Douglas Robb Memorial Lectures - Part 1](http://vega.org.uk/video/programme/45)** > > A set of four priceless archival recordings from the University of Auckland (New Zealand) of the outstanding Nobel prize-winning physicist Richard Feynman - arguably the greatest science lecturer ever. Although the recording is of modest technical... He talks about the idea of understanding at 20:15. ---
**Author:** ![Cartoonacy](https://avatars.discourse-cdn.com/v4/letter/c/848f3c/32.png) [@Cartoonacy](https://boards.straightdope.com/u/Cartoonacy)\ **Post date:** [January 6, 2012, 6:23pm UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/85 "2012-01-06T18:23:58Z")
> [@Frylock](#): > > It’s very surprising (or was anyway) but it’s not contrary to logic in any sense I can think of. No? What about [QUOTE=Wikipedia: Double-slit experiment] For example, when a laboratory apparatus was developed that could reliably fire one electron at a time through the double slit, the emergence of an interference pattern suggested that each electron was interfering with itself, and therefore in some sense the electron had to be going through both slits at once — an idea that contradicts our everyday experience of discrete objects. [/QUOTE] ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 7, 2012, 12:52am UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/86 "2012-01-07T00:52:47Z")
Fundamentally, Schrödinger’s point about the cat was that the Copenhagen interpretation of quantum mechanics led to results which seem intuitively absurd. About that, he’s right. But there are many different possible interpretations of quantum mechanics, all of them exactly equivalent in the sense that they predict the same sets of observations, and not all of them lead to that particular absurdity. The tricky part, though, is that all of them lead to their _own_ particular absurdities: Bell’s Inequality proves that any model which does not lead to one of a variety of things we consider intuitively absurd, cannot be consistent with the results of the measurements we’ve actually performed. So somehow or another, there’s _something_ about physics that we consider intuitively absurd (which should, of course, be taken as a flaw in our intuitions, not as a flaw in physics), but we can’t actually say just _what_ the absurdity is. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [January 7, 2012, 1:07am UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/87 "2012-01-07T01:07:23Z")
**Chronos**! Where the heck you been, man? 😛 ---
**Author:** ![clairobscur](https://avatars.discourse-cdn.com/v4/letter/c/839c29/32.png) [@clairobscur](https://boards.straightdope.com/u/clairobscur)\ **Post date:** [January 7, 2012, 2:17am UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/88 "2012-01-07T02:17:13Z")
> [@kombatminipig](#): > > I think you’re giving mathematicians a poor rap and giving common sense way too much credit.. No, I understand the meaning of the joke. But in the context of this thread (the OP only willing to accept unicolor sheep), it seemed to me that the emphasis should be on the mathematician (rightly) ignoring common sense. The physicist/engineer knew that the mathematician was right. The OP still struggles with the concept. 🙂 I think I’m going to search for some similar jokes. It’s been a while since I heard any. Out to find the one about the physicist and the engineer fighting a kitchen fire 😉 ETA : Immediately found some [here](http://www.farmdale.com/emp-jokes.shtml). The one I was searching for and couldn’t remember being the first one. Not really helpful for the OP, but still… ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 7, 2012, 2:34am UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/89 "2012-01-07T02:34:02Z")
Visiting my mom (who has lousy internet access) for vacation. But I’m back in the land of broadband now. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [January 7, 2012, 7:47am UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/90 "2012-01-07T07:47:59Z")
> [@clairobscur](#): > > No, I understand the meaning of the joke. But in the context of this thread (the OP only willing to accept unicolor sheep), it seemed to me that the emphasis should be on the mathematician (rightly) ignoring common sense. The physicist/engineer knew that the mathematician was right. The OP still struggles with the concept. 🙂 > > I think I’m going to search for some similar jokes. It’s been a while since I heard any. Out to find the one about the physicist and the engineer fighting a kitchen fire 😉 > > ETA : Immediately found some [here](http://www.farmdale.com/emp-jokes.shtml). The one I was searching for and couldn’t remember being the first one. Not really helpful for the OP, but still… It came to me, but I can’t remember the first two fields are. (Maybe they’re all physicists …) Three umpires answering a furious coach: Umpire 1: I calls 'em what they are. Umpire 2: I calls 'em as I see 'em. Umpire 3: They ain’t _nothin’_ till I calls 'em. ---
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [January 7, 2012, 9:01am UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/91 "2012-01-07T09:01:23Z")
Why is it so hard to believe that science has proved the existence of zombie cats? ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [January 7, 2012, 10:28am UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/92 "2012-01-07T10:28:52Z")
> [@Chronos](#): > > Fundamentally, Schrödinger’s point about the cat was that the Copenhagen interpretation of quantum mechanics led to results which seem intuitively absurd. About that, he’s right. > > \ > > Bell’s Inequality proves that any model which does not lead to one of a variety of things we consider intuitively absurd, cannot be consistent with the results of the measurements we’ve actually performed. **So somehow or another, there’s _something_ about physics that we consider intuitively absurd (which should, of course, be taken as a flaw in our intuitions, not as a flaw in physics), but we can’t actually say just _what_ the absurdity is.** This is the **Quantum Meta-Heisenberg Uncertainty Theorem** 😃 ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [January 7, 2012, 5:53pm UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/93 "2012-01-07T17:53:02Z")
> [@Leo\_Bloom](#): > > It came to me, but I can’t remember the first two fields are. (Maybe they’re all physicists …) [Absolute Zero Gravity: Science Jokes, Quotes and Anecdotes, by Betsy Devine and Joel E. Cohen](http://www.amazon.com/Absolute-Zero-Gravity-Science-Anecdotes/dp/0671740601) is full of them. If you ever stumble across a cheap copy, grab it. The best science joke book ever. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [January 8, 2012, 9:33pm UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/94 "2012-01-08T21:33:42Z")
> [@canterburyales](#): > > Many posters have recommended researching the topic to get a better understanding of the strangeness of quantum phenomenon that is being illustrated by the story of Schrodinger’s Cat. That is the best approach. > I think the heart of the matter is the difficulty in accepting the quantum view that the world seems to be inherently probabilistic. As a non-physicist I have gotten a lot out of the various Feynman lectures available online. > > This series is a good place to start: > > [The Vega Science Trust - Richard Feynman Video - The Douglas Robb Memorial Lectures - Part 1](http://vega.org.uk/video/programme/45) > > He talks about the idea of understanding at 20:15. Astounding, great great cite. I can’t wait to watch the next three lectures. Thanks. ---
**Author:** ![canterburyales](https://avatars.discourse-cdn.com/v4/letter/c/ad7895/32.png) [@canterburyales](https://boards.straightdope.com/u/canterburyales)\ **Post date:** [January 12, 2012, 3:34am UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/95 "2012-01-12T03:34:01Z")
> [@Leo\_Bloom](#): > > Astounding, great great cite. > > I can’t wait to watch the next three lectures. > > Thanks. When you are done with those check this out: > **[Microsoft Research – Emerging Technology, Computer, and Software Research](https://www.microsoft.com/en-us/research/?from=https%3A%2F%2Fresearch.microsoft.com%2Fapps%2Ftools%2Ftuva%2Findex.html&type=exact)** > > Explore research at Microsoft, a site featuring the impact of research along with publications, products, downloads, and research careers. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [April 18, 2017, 10:13pm UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/96 "2017-04-18T22:13:25Z")
> [@septimus](#): > > But it’s not that bad. A simple solution has been staring physicists in the face for decades, has been mentioned by luminaries like Wheeler and Feynmann, and avoids the Bell’s Paradox completely! > > In the Bell’s paradox, twin photons are created on Monday, then read Tuesday and Wednesday on distant asteroids. Note that the Tuesday is not preferentially “earlier” than the Wednesday reading, since each is outside the other’s cause-effect cone. Yet in the Paradox, the reading on one asteroid seems somehow telepathized to the other asteroid, faster than light, or even Wednesday’s filter setting can be seen to affect Tuesday’s reading. > > The paradox disappears if you consider that the paired photon is a single photon, [or rather a triplet of photon events — the entanglement on Monday, and the detections on Tuesday and Wednesday] … Cause-effect behaves trivially: Wednesday’s filter setting is imparted to the photon, and the polarization is “later” detected by the Tuesday receiver. > > Is there a flaw in this argument? Wheeler-Feynmann argue, IIRC, that reverse-causality photons of the type described imply _“advanced” radiation waves_ whereas only _“retarded” radiation waves_ are observed. On the other hand, wouldn’t advanced waves be quite hard to detect? (I am _not_ quite espousing the traditional Transactional model: it has an unnecessarily complex notion of causation, though I won’t try to synopsize mine in this post.) > > Just as rising entropy is a consequence of the happenstance that we inhabit a world of low entropy, couldn’t the prevalence of retarded waves be an artifact of the same thermodynamic state? Probably not, or geniuses like Feynmann would have seized on the elegance of this solution. Still, it would be nice to understand where the model fails. Yes, I realize I provide more questions than answers. But I think _my intuition_ — **that admitting retrocausality is the way Occam would be most delighted to cut with his razor** — is sound. Don’t lump me with Cramer, please. I read Huw Price. (1. Yes, I know his PhD is not in physics. 2: I had the same intuition before I read Price.) > [@Half\_Man\_Half\_Wit](#): > > **septimus** , perhaps the discussion of your idea would be something for a separate thread? Personally, I don’t see where you differ from Cramer’s transactional interpretation, and as with that interpretation, I’m not sure I really see the need. As **leahcim** notes, interpretational problems of EPR experiments mainly focus on how to save causality in the presence of apparently faster than light ‘spooky actions’ (which I consider neither spooky nor ‘actions’ in most senses of the word). To just throw out the notion of causality does seem like cheating somehow. And of course, the problems you get are those you get with any retrocausal proposal, such as paradoxical influences on the past, causal loops (i.e. A caused B retrocaused A), and of course, there’s also the problem of how our experience of a unidirectional arrow of time comes about; the usual argument of ‘entropy was lower in the past’ doesn’t work, since for every point in time, if causal influences propagate in both time directions symmetrically, one should expect that entropy is higher both towards the past and towards the future, as the dynamics that generate entropy increase work in both directions equally well. I neglected to answer **Mr. Wit** five years ago, so will do so now. 🙂 I do not “throw out the notion of causality” nor are there “faster than light actions.” Yes, the Wednesday and Tuesday events are outside each others’ causality cones, but information can tunnel(!) using the “advanced action” path from detector to entangler at the speed of the electron or photon. I’ll agree there are probably severe constraints on what _kind of information_ can be exchanged, but information _is manifestly exchanged_ in the case of EPR and GHZ paradoxes. Yes, we give up the fixity of time’s arrow. But where is that written in stone? In the the 2nd Law of T **ΔS≥0** which Mr. Wit mentions in concluding (“causal influences propagat[ing] in both time directions”): I certainly admit the possibility of boundary conditions, just as other models do, e.g. Big Bang Hypothesis, or for that matter 19th century physicists like Boltzmann. It is, apparently, the extremely low entropy at -13 Gigayear — however this boundary constraint arose — which leads to the causality arrow so clearly experienced by human brains. (This much is stipulated, I think, even by some who do not also propose retrocausality.) ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [April 22, 2017, 9:17am UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/97 "2017-04-22T09:17:27Z")
> [@septimus](#): > > Yes, I realize I provide more questions than answers. But I think _my intuition_ — **that admitting retrocausality is the way Occam would be most delighted to cut with his razor** — is sound. While I agree that retrocausality furnishes a possible explanation for Bell inequality violation, I don’t really agree that it’s a more parsimonious solution. For instance, you incur new explanatory burdens: why, if there is retrocausality, can we not actively influence the past? What additional mechanisms prevent chronology violation, or the sending of information into the past, or even to spacelike separated events? In contrast, in ordinary quantum mechanics, you merely need to give up the assumption that all measurements should obey a joint probability distribution. > [@](#): > > I do not “throw out the notion of causality” nor are there “faster than light actions.” Well, if there is retrocausality, then either there is the possibility of causes influencing their effects, or there must be a mechanism to prevent this; furthermore, you can produce FTL effects by simply sending a signal to the future, and then sending one to a different point in the past. Indeed, nonlocality and superluminal signalling are really two sides of the same coin, and retrocausation leads at least to effective nonlocality. > [@](#): > > I’ll agree there are probably severe constraints on what _kind of information_ can be exchanged, but information _is manifestly exchanged_ in the case of EPR and GHZ paradoxes. No. In fact, the No Communication-theorem entails that no information can be transmitted using entanglement alone (any more than information can be transmitted using a setup where each of us has an envelope with a colored card in it, such that yours is red if mine is green, and vice versa; opening your envelope, you’ll immediately know the color of my card, but no information has been transmitted). In order to send information, you always have to rely on classical communication > [@](#): > > I certainly admit the possibility of boundary conditions, just as other models do, e.g. Big Bang Hypothesis, or for that matter 19th century physicists like Boltzmann. Actually, I don’t think there’s really a well-posed initial value problem anymore in the presence of retrocausality; seems to me that at minimum, you’d have to also fix some far future conditions; which again entails extra explanatory burdens. ---
**Author:** ![Kedikat](https://avatars.discourse-cdn.com/v4/letter/k/ed655f/32.png) [@Kedikat](https://boards.straightdope.com/u/Kedikat)\ **Post date:** [April 22, 2017, 6:07pm UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/98 "2017-04-22T18:07:06Z")
I feel that a lot of quantum mechanics is still a manufactured framework to enable people to work in that difficult realm. It has not yet fully reflected the reality of what is going on. I liken it to navigating with two dimensional maps before you know the world is a sphere. You can make it work. But you need to invent rules in order to do it. A little creative math to straighten or curve things to plot the best path that works in the reality that you do not yet know. Many places where there be monsters. That doesn’t mean it does not work. We use flat maps all the time and get where we want to go. Quantum mechanics is a developing map. It helps explore that world. The explorers may at some point see it for what it is. Possibly far outside the boundaries of their map. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [April 22, 2017, 6:45pm UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/99 "2017-04-22T18:45:36Z")
To clarify for other users due to the use of various terms in this thread. EPR experiment nor any other quantum experiment has demonstrated that faster-than-light signaling is possible. The lack of transfer of usable “faster-than-light signaling” or what is commonly also called information has not been demonstrated. Because of this lack of useable information the speed of causality is not violated at this date. While a lack of a unifying theory may make these paradoxes fairly confusing as there is a significant amount of unsettled science the restriction on the speed of causality is related to communication faster than the speed of light and not other aspects of our universe. In fact in the future even the expansion of the universe is expected to exceed the speed of light. This does not imply that the particles themselves are superluminal, but that the distances between them will be. As of this date the no-communication theorem is still firmly in place. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [April 22, 2017, 7:22pm UTC](https://boards.straightdope.com/t/schrodingers-cat/608260/100 "2017-04-22T19:22:24Z")
Alice and Bob each take one of an entangled pair. Alice reads the Z spin on one of the entangled pair but Bob doesn’t have a way to detect that she did. Alice can’t control what the value is that will be read, she reads a "random value. Alice my read an up or a down. Bob will read a complement of Alice’s “random” value, to Bob it appears random as well. Bob would need a way to know that Alice has actually performed a measurement or if he is the first one to measure a member of the pair. Bob’s statistics for his particle alone look the same either way. If Alice and Bob are not local to each other they cannot tell if something is random or due to entanglement. It is easy to confuse tests that do have locality and non FTL communication with thought experiments that describe how entanglement interactions are FTL but to reference Kedikats post remember that most of the math is in done in Hilbert space or other Euclidean spaces and thus will not apply to space like intervals. While our theories are incomplete, any violation of the speed of **causality** is purely theoretical and there is no experimental proof for “faster-than-light signaling” but only for “faster-than-light interactions”. I do want to address this from the OP: > [@whc.03grady](#): > > Why does the physicist get to invent a property (the superposition) that is, _in principle_, unobservable While others have cited tests for this theory I also wanted to point out that it was recently observed on a physical object. > **[Quantum effect spotted in a visible object – Physics World](https://physicsworld.com/a/quantum-effect-spotted-in-a-visible-object/)** > > An important step towards testing Schrödinger's cat paradox [Previous page](https://boards.straightdope.com/t/schrodingers-cat/608260.md?page=4) [Next page](https://boards.straightdope.com/t/schrodingers-cat/608260.md?page=6)