Schrödinger’s Cat


This theoretical experiment which is about to be discussed is still a hot topic among many physicists worldwide and I would like you (the reader) to pay close attention to each and every word in this article in order to figure out what I hope to convey.

Schrödinger’s Cat, as the name suggests was a mind experiment performed by Erwin Schrödinger, an Austrian quantum physicist in 1935. Here’s how it’s done: We place a living cat in a sealed box along with a radioactive sample, a Geiger counter and a bottle of hydrocyanic acid (poison). The detector is turned on for just long enough that there is a fifty-fifty chance that the radioactive material will decay. If the substance does decay, the Geiger counter detects the particle and a relay mechanism will trip a hammer, which will, in turn, break the bottle of cyanide, killing the cat. If the substance does not decay, the cat lives.

Before we move on to the outcome, let’s have a look at what we call the ‘wave function’. So what is this wave function? The wave function of a particle is the probability of finding the particle at that specific position at that time and is also used in Schrödinger’s equation.

According to quantum physics, “It is physically impossible to know both the position and the momentum of a particle at the same time. The more precisely one is known, the less precise the measurement of the other is.” This is known as the Heisenberg Uncertainty principle. Each possible route that the electron could take, called a ghost, could be described by a wave function. That is, an electron could be anywhere within the space of an atom at a given time.

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Now let’s move onto the outcome. The observer cannot know whether or not an atom of the substance has decayed, whether the poison has been released and thus, whether the cat is dead. According to quantum law, the cat is both dead AND alive until the box is opened. But when the box is opened, at the time of detection, the wave function collapses and the cat is either dead OR alive. This situation is called the observer’s paradox.

The experiment was designed to illustrate the flaws of the ‘Copenhagen Interpretation’ of quantum theory. The Copenhagen Interpretation was proposed by Neils Bohr who worked in Copenhagen and it suggests that “The observation itself affects an outcome, so that the outcome alone does not exist unless we observe it”. In simple terms, before we look into the box, the cat is in a ‘superposition’, it is both dead AND alive, and our act of looking forces nature’s decision. That is, the two possibilities collapse into one reality, either the cat dies or lives. This collapsing into one reality is one of the biggest unanswered questions in quantum physics!

While there are many different interpretations that solve the problem of Schrödinger’s Cat, none of them are satisfactory enough to disprove the Copenhagen Interpretation which brings forth the theory of the half-dead cat!

Schrödinger himself is rumored to have said, later in life, that he wished he had never met that cat.