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NeuroQuantology

The Quantum Measurement Problem: How to Rescue a Cat from Schizophrenia?

Sultan Tarlacı

Published Dec 9, 2011• 1 citation

Abstract

The implementation of quantum theory was presented to our macroscopic world by the “cat” thought experiment (Gedanken experiment) suggested by Erwin Schrodinger in 1935. In the same way, Pavlov’s dog with its learning by conditioned reflexes was a similar symbol of Newtonian physics representing the deterministic view, and the cat as an animal became the symbol of quantum mechanics. Thought experiments are a common technique in physics. Before everything, it is important to see whether the experiment can be carried out at all, and it is unimportant how complex the relevant techniques to be used in the experiment. This is because there is only a design and a thought experiment. Imagination and materials are unlimited, and the only constraining factors are the laws of mathematics and physics. If you feel sorry for the cat, you might prefer the experiment suggested by Einstein, which uses a box containing a bomb, a photon, an electron, or playing cards. In this article, we reviewed possible solutions of the quantum measurement problem or quantum wavefunction collapse. NeuroQuantology | September 2012 | Volume 10 | Issue 3 | Page 519-531

DOI: 10.14704/nq.2012.10.3.442

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The most discussed thought experiment in quantum mechanics (QM) is the one of the dead+living cat, which sets out to explain what is known as the measurement problem. Since the first years of QM, and despite various arguments, the widespread beliefs of the past few years have tended towards including a conscious observer in the act of measurement. Various different opinions have been expressed on the measurement problem by various schools of thought and leading physicists, but none of them has been decisive. Especially, the introduction of an observer (human-brain-consciousness-mind-intelligence) carrying out measurements into the experiment or into the setup of the experiment has led to even more complex problems. Today also, new solutions are being put forward. This article deals with the thought experiment of Schrodinger’s cat and suggestions for alternative solutions by introducing a conscious observer. NeuroQuantology |June 2012 | Volume 10 | Issue 2 | Page 216-229

In 1935, Erwin Schrödinger suggested his famous gedanken experiment of the cat that is simultaneously "dead" and "alive" inside its box until the box is opened. But as Tesche explains in her Perspective, such a macroscopic manifestation of quantum mechanics has remained elusive until recently. The experiments by van der Wal et al. are an important step toward demonstrating that quantum mechanics can describe macroscopic phenomena. The approach may be exploited in quantum computing and quantum cryptography.

In 1935 Erwin Schrödinger proposed a thought experiment to show the absurd consequences of applying quantum mechanics to everyday objects. Schrödinger imagined placing a cat in a box, along with a vial of deadly poison that is connected to a radioactive atom. If the atom decays, it releases the poison and kills the cat. When the box is closed we do not know if the atom has decayed or not, which means that it can be in a "superposition" of two states (decayed and non-decayed) at the same time. Therefore, protested Schrödinger, the cat can be both dead and alive at the same time – which is clearly absurd. There was obviously, he thought, some boundary between the microscopic world of atoms and quantum mechanics, and the macroscopic world of cats and classical mechanics.

The physicist Erwin Schrödinger described, back in 1935, one aspect of this strange phenomenon. He placed his cat in a sealed box with a piece of radioactive material which might or might not send out a sub-atomic particle. If it did, the Geiger counter was designed to trigger a release of poisonous gas in the box, and thereby kill his cat. The counter was set up to be triggered just enough to give a 50-50 chance of a particle being detected, and therefore the cat an even chance of being poisoned or not. (In those days, this sort of experiment was acceptable, particularly as it was only a thought experiment.) Radioactive behaviour is unpredictable (except in a general, statistical probability kind of way). There is no rule for working out whether or not the Geiger counter will be triggered. If the sub-atomic event does not occur, the cat lives. Otherwise, it dies. Just as a photon (in that famous experiment from ‘real-life’ physics) will quite happily go through both of two parallel slits in a screen – until someone tries to measure or detect it, at which point what the physicists call ‘the collapse of the wave function’ takes place – the particle can both trigger the poison gas and not trigger the poison gas. That is, until someone looks, Schrödinger’s idea is that his cat, for a while, is both alive and dead!