8
edits
Changes
Jump to navigation
Jump to search
mLine 1:
Line 1: − == Schrödinger's cat ==+ − − Schrödinger's cat is a famous illustration of the principle in quantum theory of superposition, proposed by [[Erwin Schrödinger]] in 1935. Schrödinger's cat serves to demonstrate the apparent conflict between what quantum theory tells us is true about the nature and behavior of matter on the microscopic level and what we observe to be true about the nature and behavior of matter on the macroscopic level. − Here's Schrödinger's (theoretical) experiment: We place a living [[cat]] into a [[steel]] chamber, along with a device containing a vial of hydrocyanic [[acid]]. There is, in the chamber, a very small amount of a radioactive substance. If even a single atom of the substance decays during the test period, a relay mechanism will trip a [[hammer]], which will, in turn, break the vial and kill the cat. The observer cannot know whether or not an [[atom]] of the substance has decayed, and consequently, cannot know whether the vial has been broken, the hydrocyanic acid released, and the cat killed. Since we cannot know, the cat is both dead and alive according to quantum law, in a superposition of states. It is only when we break open the box and learn the condition of the cat that the superposition is lost, and the cat becomes one or the other (dead or alive). This situation is sometimes called quantum indeterminacy or the observer's paradox: the observation or measurement itself affects an outcome, so that the outcome as such does not exist unless the measurement is made. (That is, there is no single outcome unless it is observed.)+ − − We know that superposition actually occurs at the subatomic level, because there are observable effects of interference, in which a single particle is demonstrated to be in multiple locations simultaneously. What that fact implies about the nature of reality on the observable level (cats, for example, as opposed to electrons) is one of the stickiest areas of quantum physics. Schrödinger himself is rumored to have said, later in life, that he wished he had never met that cat. − Here is a famous letter asking about the phenomenon to [[Cecil Adams]], writer for the [[Straight Dope]]. − Dear Cecil:+ − Cecil, you're my final hope − Of finding out the true Straight Dope − For I have been reading of Schroedinger's cat − But none of my cats are at all like that. − This unusual animal (so it is said) − Is simultaneously live and dead! − What I don't understand is just why he − Can't be one or other, unquestionably. − My future now hangs in between eigenstates. − In one I'm enlightened, the other I ain't. − If you understand, Cecil, then show me the way − And rescue my psyche from quantum decay. − But if this queer thing has perplexed even you, − Then I will and won't see you in Schroedinger's zoo. − --Randy F., Chicago − Dear Randy:+ − Schroedinger, Erwin! Professor of physics! − Wrote daring equations! Confounded his critics! − (Not bad, eh? Don't worry. This part of the verse − Starts off pretty good, but it gets a lot worse.) − Win saw that the theory that Newton'd invented − By Einstein's discov'ries had been badly dented. − What now? wailed his colleagues. Said Erwin, "Don't panic, − No grease monkey I, but a quantum mechanic. − Consider electrons. Now, these teeny articles − Are sometimes like waves, and then sometimes like particles. − If that's not confusing, the nuclear dance − Of electrons and suchlike is governed by chance! − No sweat, though--my theory permits us to judge − Where some of 'em is and the rest of 'em was." − Not everyone bought this. It threatened to wreck − The comforting linkage of cause and effect. − E'en Einstein had doubts, and so Schroedinger tried − To tell him what quantum mechanics implied. − Said Win to Al, "Brother, suppose we've a cat, − And inside a tube we have put that cat at-- − Along with a solitaire deck and some Fritos, − A bottle of Night Train, a couple mosquitoes − (Or something else rhyming) and, oh, if you got 'em, − One vial prussic acid, one decaying ottom − Or atom--whatever--but when it emits, − A trigger device blasts the vial into bits − Which snuffs our poor kitty. The odds of this crime − Are 50 to 50 per hour each time. − The cylinder's sealed. The hour's passed away. Is − Our pussy still purring--or pushing up daisies? − Now, you'd say the cat either lives or it don't − But quantum mechanics is stubborn and won't. − Statistically speaking, the cat (goes the joke), − Is half a cat breathing and half a cat croaked. − To some this may seem a ridiculous split, − But quantum mechanics must answer, "Tough @#&! − We may not know much, but one thing's fo' sho': − There's things in the cosmos that we cannot know. − Shine light on electrons--you'll cause them to swerve. − The act of observing disturbs the observed-- − Which ruins your test. But then if there's no testing − To see if a particle's moving or resting − Why try to conjecture? Pure useless endeavor! − We know probability--certainty, never.' − The effect of this notion? I very much fear − 'Twill make doubtful all things that were formerly clear. − Till soon the cat doctors will say in reports, − "We've just flipped a coin and we've learned he's a corpse."' − So saith Herr Erwin. Quoth Albert, "You're nuts. − God doesn't play dice with the universe, putz. − I'll prove it!" he said, and the Lord knows he tried-- − In vain--until fin'ly he more or less died. − Win spoke at the funeral: "Listen, dear friends, − Sweet Al was my buddy. I must make amends. − Though he doubted my theory, I'll say of this saint: − Ten-to-one he's in heaven--but five bucks says he ain't." − --CECIL ADAMS − + − Here's Schrödinger's (theoretical) experiment: We place a living cat into a steel chamber, along with a device containing a vial of hydrocyanic acid. There is, in the chamber, a very small amount of a radioactive substance. If even a single atom of the substance decays during the test period, a relay mechanism will trip a hammer, which will, in turn, break the vial and kill the cat. The observer cannot know whether or not an atom of the substance has decayed, and consequently, cannot know whether the vial has been broken, the hydrocyanic acid released, and the cat killed. Since we cannot know, the cat is both dead and alive according to quantum law, in a superposition of states. It is only when we break open the box and learn the condition of the cat that the superposition is lost, and the cat becomes one or the other (dead or alive). This situation is sometimes called quantum indeterminacy or the observer's paradox: the observation or measurement itself affects an outcome, so that the outcome as such does not exist unless the measurement is made. (That is, unless it is observed.) + − We know that superposition actually occurs at the subatomic level, because there are observable effects of interference, in which a single particle is demonstrated to be in multiple locations simultaneously. What that fact implies about the nature of reality on the observable level is one of the stickiest areas of quantum physics.+ + + + + + + + + + + + + + + + + + + + + + + + + + + + +
rm cw stuff
When scientists and historians mention "Schrödinger's Cat" they are usually referring to the seemingly paradoxical thought experiment devised by Erwin Schrödinger that attempts to illustrate that early interpretations of quantum mechanics were overrated and dumb. It has only lately been discovered that so-called "Schrödinger's Cat" was actually many cats, which Schrödinger sacrificed in the name of scientific discovery until he found the results he wanted. Controversy over Schrödinger's methods and findings has raged throughout the scientific community over the past 45 years and has recently spilled over into the realm of social activism.
== Origins ==
Schrödinger proposed his "cat" experiment after debates with Albert Einstein over the Copenhagen interpretation, which Schrödinger defended, stating that if a scenario existed where a cat could be so isolated from external interference (decoherence), the state of the cat can only be known as a superposition (combination) of possible rest states (eigenstates), because finding out (measuring the state) cannot be done without the observer interfering with the experiment — the measurement system (the observer) is entangled with the experiment.
Einstein, believing that Schrödinger was speaking only figuratively, demanded that he "prove it," prompting Schrödinger to retreat to a remote island in the Caribbean to perform his now-famous set of experiments that at that time were kept well under wraps.
Schrödinger's cat is a famous illustration of the principle in quantum theory of superposition, proposed by Erwin Schrödinger in 1935. Schrödinger's cat serves to demonstrate the apparent conflict between what quantum theory tells us is true about the nature and behavior of matter on the microscopic level and what we observe to be true about the nature and behavior of matter on the macroscopic level.
== The Experiment ==
Notebooks found at Schrödinger's Caribbean estate reveal his original layout for the series of experiments:
"A cat is penned up in a steel chamber, along with the following device (which must be secured against direct interference by the cat): in a Geiger counter there is a tiny bit of radioactive substance, so small, that perhaps in the course of the hour one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges and through a relay releases a hammer which shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. The psi-function of the entire system would express this by having in it the living and dead cat mixed or smeared out in equal parts."
Schrödinger experimented with approximately 10 different cats, most of which were picked up locally as strays. However, the final three cats used were in fact Schrödinger's own pets. Mittens, an 8-year-old silver American shorthair, survived two runs of the experiment, emerging entirely alive from the steel chamber in two consecutive experiments. Sport, a playful and robust Havana Brown, survived the first run but in the second was killed by the radioactive material. Unfortunately, Sport's state at death was entirely cohesive, contributing nothing toward Schrödinger's hypothesis. Finally, Schrödinger found success with his long-time favorite pet Mr. Whiskers, an elderly striped tabby whose frailty may have contributed in a small part to the eventual success of the experiment. Mr. Whiskers was placed in the steel chamber and left in the system for over an hour. Upon his return, Schrödinger found Mr. Whiskers part-dead and part-alive, with the matter of each half, as expected, "mixed or smeared out in equal parts."
Schrödinger is said to have jumped from his bathtub and cried "Eureka!" when this happened, but so far no sources have been able to corroborate this. Skeptics say that Schrödinger would have to have been sitting in the bathtub at the time of the discovery for this to have happened, meaning the experimental system was set up in his bathroom. Inspection of the estate shows that the only bathroom large enough to accomodate both Schrödinger's tub and the steel-chambered mechanism was the upstairs master bathroom, which diary entries suggest that the superstitious Schrödinger never used, believing there were "ghosts" in that room. The so-called "Eureka!" incident has remained a point of bitter contention among physicists and historical biographers alike.
== Conclusions ==
Schrödinger did not immediately tell Einstein that he had found the solution. Finding it necessary to conceal the evidence of the physical experiments that went on in his lab, Schrödinger was compelled to create an entirely false set of experimental data, mathematical and theoretical in nature, that would describe his results without revealing that they had been carried out on actual living cats. Einstein was impressed with Schrödinger's findings, sending him a congratulatory letter which said the following:
"You are the only contemporary physicist, besides Laue, who sees that one cannot get around the assumption of reality—if only one is honest. Most of them simply do not see what sort of risky game they are playing with reality—reality as something independent of what is experimentally established. Their interpretation is, however, refuted most elegantly by your system of radioactive atom + amplifier + charge of gun powder + cat in a box, in which the psi-function of the system contains both the cat alive and blown to bits. Nobody really doubts that the presence or absence of the cat is something independent of the act of observation."
Apparently after receiving this letter, Schrödinger wrote in his diary, "It never occurred to me to use, instead of a live cat, an unstable keg of gun powder. In retrospect, this approach may have been more humane. I do feel, though, that my achievements in the realm of scientific progress far outway questions of my potential immorality."
In the scientific world, Schrödinger's foolproof results merited much respect; the "Schrödinger's Cat" theory became one of the most famous and compelling defenses of the Copenhagen school of quantum mechanics.
== Controversy ==
It came as a shock to the world of science when, following Schrödinger's death in 1961, an exploration of his estate and the finding of hidden data and diary entries revealed the grisly nature of his experiments. Determined not to let the unflattering truth impugn the integrity of the Copenhagen school, many of its leading proponents, most notably German physicist Werner Heisenberg, fought to repress much of the information that came out on Schrödinger. Widespread awareness of the "Schrödinger's Cats" scandal did not catch on until the late 1980s, when the animal rights group PETA used obscure derogatory references to Schrödinger's career in an early ad campaign.
There is still some dispute over exactly how many cats were used in Schrödinger's experiments. While the generally accepted tally is 10, estimates range anywhere from 5 to 500 animals killed. Animal Rights activists have demanded that an official investigation be launched into Schrödinger's little-known scientific processes. In 2005, the Austrian estate of Erwin Schrödinger refused a request for $10 million in compensation to be distributed among various animal-friendly charities. A movement has been made recently to rename the "Schrödinger's Cat" theory "Schrödinger's Cats," a politically correct label which would more aptly honor the dead. So far, "Schrödinger's Cat" has remained the accepted term.