Schrodinger’s cat

Gribbin, John. In Search of Schrodinger s Cat Quantum Physics and Reality. New York Bantam Books, 1984. 

Schrodinger, E. (1 983) The present situation in quantum mechanics A translation of Schrodinger s "Cat Paradox" paper,in Wheeler, J. A. and Zurek, W. H.(eds.), Quantum theory and measurement, Princeton University Press, Princeton,New Jersey,pp.152-167. 

The remarkable conclusion is that the microscopic quantum state, specified by the wave function ip, can be described on a macroscopic level by the probability distribution Pj. A single pure state corresponds to a macroscopic ensemble. The interference terms that are typical for quantum mechanics no longer appear. Incidentally, this resolves the paradox of Schrodinger s cat and, in general, the quantum mechanical measurement problem. )... 

Volumes have been written about the red herring known as Schrodinger s cat. Without science writers looking for sensation, it is difficult to see how such nonsense could ever become a topic for serious scientific discussion. Any linear differential equation has an infinity of solutions and a linear combination of any two of these is another solution. To describe situations of physical interest such an equation is correctly prepared by the specification of appropriate boundary conditions, which eliminate the bulk of all possible solutions as irrelevant. Schrodinger s equation is a linear differential equation of the Sturm-Liouville type. It has solutions, known as eigenfunctions, the sum total of which constitutes a state function or wave function, which carries... 

The application of quantum mechanics to physical problems is now routine with most physicists. It is used daily to guide the design of experiments and to explain their results. Every prediction made by means of quantum mechanics has been accurate. It has been an enormously successful physical theory, yet one that no physicist will claim to understand. From the beginning it was apparent that quantum mechanics required a new and novel way of thinking about the natural world and about reality. That brings us back to Schrodinger s cat. 

The cat paradox was presented in a paper, The Present Situation in Quantum Mechanics, which Schrodinger wrote in 1935. Since then, Schrodinger s imaginary cat has been a provocative source of debate. Of course, the paradoxical nature of Schrodinger s cat is, at least in part, couched in the act of applying concepts designed to account for the behavior of a subatomic object like an electron to a macroscopic object like a cat. This situa-... 

Phenomena in the submicroscopic quantum world inevitably create apparent paradoxes from the viewpoint of classical macroscopic experience. We will focus in this chapter on two of the most counterintuitive aspects of quantum theory superposition (SchrOdinger s Cat) and entanglement (EPR and Bell s theorem). 

Interactions between adjacent particles of condensed phases can lead to quantum correlations, quantum interference, entanglement and decoherence, delocalization and "Schrodinger s cat" states. Such effects are theoretically expected to be extremely short-lived, due to environmental disturbances. Therefore, it has been widely believed that they cannot be experimentally detected. However, based on previous theoretical work (cf. [Chatzidimitriou-Dreismann 1995 Chatzidimitriou-Dreismann 1997 (b)]), we proposed to detect QE in condensed systems by means of sufficiently "fast" scattering techniques. Particularly suitable for this purpose is the NCS method. Our NCS investigations (on liquid H2O - D2O mixtures [Chatzidimitriou-Dreismann 1997 (a)]) started 1995 and have provided, for the first time, direct experimental evidence of attosecond QE between a proton and its adjacent particles. 

Li, X. and Darzynkiewicz, Z. (1999) The Schrodinger s cat quandary in cell biology integration of live cell functional assays with measurements of fixed cells in analysis of apoptosis. Exp. Cell Res. 249, 404-412. 

In the usual EPR model, the only variables considered are the six components of the two spins all the rest has been thrown away. There are no masses, charges, positions, velocities, interactions, nor even particles - only two disembodied spins. To use the imagery of Schrodinger s cat , this is a Lewis Carrol s Cheshire cat the spin without the particle is like the grin without the cat. 

During my student days (pre-university, university, PhD), we learned quantum mechanics from the books authored by L. D. Landau and E. M. Lifshitz, A. S. Davydov, D. Bohm, Feynman s course of Lectures on Physics, and from P. A. M. Dirac s Principles . We were exeited with the theories of hidden variables, EPR paradox, decoherence, entanglement, and concerned for a life of immortal Schrodinger s cat - they were in the air at that time Did I understand it Yes - because, due to a conventional wisdom, I used it more than 24 hours a day and every day. I however doubt - doubt together with Feynman who once remarked that Nobody understands it - that I ve actually understood it. I touched and used it throughout the molecular world, which is nowadays inhabited by 21 million molecules, and which I studied as a quantum chemist - in fact, by education, I am a theoretical physicist. 

One of the most famous thought experiments put forward in the early days of the quantum theory was formulated by Schrodinger and is now known as Schrodinger s cat This experiment called into question whether a system could have multiple acceptable wave functions prior to observation of the system. In other words, if we don t actually observe a system, can we know anything about the state it is in ... 

Schrodinger posed this paradox to point out weaknesses in some interpretations of quantum results, but the paradox has led instead to a continuing and lively debate about the fate and meaning of Schrodinger s cat. In 2012, the Nobel Prize in physics was awarded to Serge Haroche of France and David Wineland of the United States... 

As discussed in the A Closer Look box on Measurement and the Uncertainty Principle, the essence of the uncertainty principle is that we can t make a measurement without disturbing the system that we are measuring, (a) Why can t we measure the position of a subatomic particle without disturbing it (b) How is this concept related to the paradox discussed in the Closer Look box on Thought Experiments and Schrodinger s Cat ... 

Basic Forces 49 The Mass Spectrometer What Are Coins Made Of 54 Energy, Enthalpy, and P-V Work 178 Measurement and the Uncertainty Principle 225 Thought Experiments and Schrodinger s Cat 226 Probability Density and Radial Probability Functions 232 Effective Nuclear Charge 261... 

The above mentioned paper by Einstein, Podolsky, and Rosen represented a severe critique of quantum mechanics in the form that has been presented by its fathers. After its publication, Erwin Schrodinger published a series of works showing some other problematic issues in quantum mechanics. In particular, he described a Gedanken experiment, later known as the Schrodinger s cat paradox. According to Schrodinger, this paradox shows some absurd consequences of quantum mechanics. 

There is no absolute knowledge in science and the scientific method assumes that there is a material world of objects and phenomena existing out there that is independent of the observers, the scientists. However, some physicists might question the assertion that the material world is independent of the observers. Thus, Schrodinger s cat is both alive and dead until the observation is made, i.e. the box is opened, the wave function is collapsed, and one of the eventualities - alive or dead - is manifested. 

John Gribbin in his book In Search of Schrodinger s Cat says not only do we not know what an atom is really we cannot ever know what an atom is really. We can only know what an atom is like. By probing it certain ways, we find that under those circumstances, it is like a billiard ball. Probe it another way and we find it is like a solar system. Ask a third set of questions, and the answer we get is it is like a positively charged nucleus surrounded by a fuzzy cloud of electrons (Gribbin, 1984). 

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