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Liam Garcia
Liam Garcia

Into Schrodinger's Box

In Schrödinger's original formulation, a cat, a flask of poison, and a radioactive source are placed in a sealed box. If an internal monitor (e.g. a Geiger counter) detects radioactivity (i.e. a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. The Copenhagen interpretation implies that, after a while, the cat is simultaneously alive and dead. Yet, when one looks in the box, one sees the cat either alive or dead, not both alive and dead. This poses the question of when exactly quantum superposition ends and reality resolves into one possibility or the other.

Into Schrodinger's Box

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The prevailing theory, called the Copenhagen interpretation, says that a quantum system remains in superposition until it interacts with, or is observed by the external world. When this happens, the superposition collapses into one or another of the possible definite states. The EPR experiment shows that a system with multiple particles separated by large distances can be in such a superposition. Schrödinger and Einstein exchanged letters about Einstein's EPR article, in the course of which Einstein pointed out that the state of an unstable keg of gunpowder will, after a while, contain a superposition of both exploded and unexploded states.[4]

It is typical of these cases that an indeterminacy originally restricted to the atomic domain becomes transformed into macroscopic indeterminacy, which can then be resolved by direct observation. That prevents us from so naïvely accepting as valid a "blurred model" for representing reality. In itself, it would not embody anything unclear or contradictory. There is a difference between a shaky or out-of-focus photograph and a snapshot of clouds and fog banks.

A commonly held interpretation of quantum mechanics is the Copenhagen interpretation.[10] In the Copenhagen interpretation, a system stops being a superposition of states and becomes either one or the other when an observation takes place. This thought experiment makes apparent the fact that the nature of measurement, or observation, is not well-defined in this interpretation. The experiment can be interpreted to mean that while the box is closed, the system simultaneously exists in a superposition of the states "decayed nucleus/dead cat" and "undecayed nucleus/living cat", and that only when the box is opened and an observation performed does the wave function collapse into one of the two states.

In 1957, Hugh Everett formulated the many-worlds interpretation of quantum mechanics, which does not single out observation as a special process. In the many-worlds interpretation, both alive and dead states of the cat persist after the box is opened, but are decoherent from each other. In other words, when the box is opened, the observer and the possibly-dead cat split into an observer looking at a box with a dead cat, and an observer looking at a box with a live cat. But since the dead and alive states are decoherent, there is no effective communication or interaction between them.

The relational interpretation makes no fundamental distinction between the human experimenter, the cat, or the apparatus, or between animate and inanimate systems; all are quantum systems governed by the same rules of wavefunction evolution, and all may be considered "observers". But the relational interpretation allows that different observers can give different accounts of the same series of events, depending on the information they have about the system.[25] The cat can be considered an observer of the apparatus; meanwhile, the experimenter can be considered another observer of the system in the box (the cat plus the apparatus). Before the box is opened, the cat, by nature of its being alive or dead, has information about the state of the apparatus (the atom has either decayed or not decayed); but the experimenter does not have information about the state of the box contents. In this way, the two observers simultaneously have different accounts of the situation: To the cat, the wavefunction of the apparatus has appeared to "collapse"; to the experimenter, the contents of the box appear to be in superposition. Not until the box is opened, and both observers have the same information about what happened, do both system states appear to "collapse" into the same definite result, a cat that is either alive or dead.

On the other hand, the anti-Zeno effect accelerates the changes. For example, if you peek a look into the cat box frequently you may either cause delays to the fateful choice or, conversely, accelerate it. Both the Zeno effect and the anti-Zeno effect are real and known to happen to real atoms. The quantum system being measured must be strongly coupled to the surrounding environment (in this case to the apparatus, the experiment room ... etc.) in order to obtain more accurate information. But while there is no information passed to the outside world, it is considered to be a quasi-measurement, but as soon as the information about the cat's well-being is passed on to the outside world (by peeking into the box) quasi-measurement turns into measurement. Quasi-measurements, like measurements, cause the Zeno effects.[27] Zeno effects teach us that even without peeking into the box, the death of the cat would have been delayed or accelerated anyway due to its environment.

According to objective collapse theories, superpositions are destroyed spontaneously (irrespective of external observation), when some objective physical threshold (of time, mass, temperature, irreversibility, etc.) is reached. Thus, the cat would be expected to have settled into a definite state long before the box is opened. This could loosely be phrased as "the cat observes itself", or "the environment observes the cat".

This constellation depicts the feline-equipped box at the center of a famous thought experiment devised by Austrian physicist Erwin Schrödinger in 1935. He imagined placing a cat into an opaque box along with a device that would release poison if a random subatomic event, like the decay of a radioactive atom, occurred. Because scientists cannot predict when the decay would happen, the only way to know the fate of the cat at any moment is by opening the box. As described by quantum mechanics, the cat is simultaneously alive and dead until it is observed. Schrödinger considered this "quite ridiculous" and, with the support of other scientists like Albert Einstein, used it to challenge the prevailing interpretation of quantum mechanics at the time.

So Fermi's LAT takes advantage of a phenomenon called "pair conversion." When an energetic gamma ray interacts with one of the tungsten plates inside the LAT, it converts into an electron and its antimatter counterpart, a positron. The LAT then tracks the electron to determine what part of the sky the original gamma ray came from.

The St. Lucie County Emergency Operations Center, where I was stationed during the storm, felt less like the public help center and more like the inside of a battleship. The command room (not open to the public) boasted four massive screens tuned into different channels, each with a different weather report, while officials decided how to best allocate their precious resources and fleeting time before Matthew brought its Category 4 winds to land.

None of that happened. Not even close. Instead, we watched the TV as if it were a glass door into Schrodinger's Box, with uncertainty about Matthew's path keeping us glued. We directed our energy not at each other, but rather at the monumental storm beating down our front door. Reporters traded information while various agency representatives bonded over nicotine and coffee.

That's easy enough to understand. But an awesome subtlety turns it into a new tenet of scientific faith. It makes precise measurement unthinkable. And that means we no longer have reason for thinking the world has any ultimate precision to measure.

Schrödinger said that if that's the case, let's seal a cat, a geiger counter, a fragment of radioactive material, and a bottle of poison gas into a box for one hour. There's a 50-50 chance that radioactive decay will trigger the geiger counter, activate a mechanism that breaks the bottle, and poison the cat. He asks if we'll find a live cat or a dead one when we open the box.

The system can be represented as a potential well with two minima, both of which contain several bound states, separated by a barrier. Friedman and co-workers start with a current of about 1 microamp flowing in, say, the clockwise direction. Next they illuminate the SQUID with microwaves which excite the system to a clockwise state with higher energy. The system can now tunnel from the clockwise state into the anti-clockwise state, and back.

The story behind the puzzle is based on Schrodingers's cat: In 1935, Vienna, an Austrian physicist Erwin Schrodinger conducted experiments in the area of quantum mechanics and demonstrated that it could be applied to everyday objects. In his experiment a cat and a portion of poison were put into a box. Quantum mechanics says that after a while, the cat will be both alive and dead. Unforumately, Schrodinger got busy and completely forgot about the cat.... We're sure the cat is still alive. Now it's time to rescue it!

Schrodinger is most widely known these days for a theoretical experiment he described about a cat in a box. The experiment went something like this: what if you placed a cat into a box with a hammer, a vial of poison, radioactive material, and a Geiger counter?

Anyone with a passing interest in quantum theory (no, seriously - bear with me) will probably be familiar with Schrodinger's Cat. For the uninitiated, the moggy in question is part of a famous thought experiment in which a cat is sealed into a box, and there's a random chance that it may be killed while in this box. However, according to Erwin Schrodinger, who thought up the experiment and presumably didn't like cats very much, in quantum mechanics, the cat is neither alive nor dead while it is in the box - instead, it exists in both states, and those states are only resolved when the box is opened and someone peers in. 041b061a72


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