Erwin Schrödinger between equations, cats and philosophy (and a life-size installation in Zurich)

It was 1935 when Austrian physicist Erwin Schrödinger came up with the infamous thought experiment which he would be remembered for, while discussing with Albert Einstein the problems of the Copenhagen interpretation of quantum mechanics.

Born on 12th August 1887, he was a man who would go on to revolutionize not only the field of physics, but also biology.
From a very young age, he had shown immense talent for mathematics and physics, but he also had interests in poetry and philosophy.
During his time at the University of Zurich, he published a lot of papers on thermodynamics, but he was not happy with Niels Bohr’s old quantum theory. As his background with eigenvalue problems would suggest, he believed that atomic spectra should be determined by some kind of eigenvalue problem.
Thus he came up with an equation which could be used to find the energy states of an atom and that describes the Hamiltonian operator, which when operated on an abstract mathematical function called the wave function, produced energy as a result.
This equation brought him the 1933 Nobel Prize in physics, along with Paul Dirac but, among other meritocracy, new concepts like hybridization were also discovered and chemistry, physics and science would never be the same again.
His theory, known as wave mechanics, also gave a complete description of the spectral lines of the hydrogen atom.
At the time, It was widely accepted that matter exhibits both particle and wave properties. However, Schrödinger soon began to suspect this view, he started to believe that waves alone can describe everything and, in short, that particles were useless, proposing that a particle is just a wave group with small dimensions in all directions.
The widely accepted view held that quantum states exist in a superposition, and everything is thus reduced to probability by quantum mechanics.
Schrödinger, however, was dissatisfied with this view, and to demonstrate how absurd the idea is, he put forward a thought experiment.

The experiment, known as Schrödinger’s Cat, consists of three items sealed inside a box: a cat, a radioactive source, and a flask of poison.
The latter is connected to a hammer, which in turn is connected with a Geiger counter, a device which can detect radioactive decay.
Should the internal Geiger counter detect radioactivity, the contraption would break the flask open, releasing the poison and, according to the interpretation, the cat would be simultaneously alive and dead.
It would remain in this state until the box is opened.
Well, but how can a cat be dead and alive at the same time?
This is Schrödinger’s famous cat paradox.
While Schrödinger believed that this thought experiment would disprove the idea of superposition and probability once and for all, it actually gave rise to many new interpretations of quantum mechanics.

Today, in the garden of the Zu Vier Wachten (At the Four Guards) house on Huttenstrasse where he lived 1921 – 1926, a life-size figure of a cat can be found.
Interestingly, depending on the light conditions of the day, it may appear alive or dead, just like the popular experiment.
The installation is not just a playful representation of a scientific thought experiment – it also raises important questions about the nature of reality and the role of the observer, highlighting the idea that our perception of reality is shaped by our own observations and experiences.

In any case, as American author and historian of science whose work has chronicled the cultural impact of modern technology James Gleick said: “In Schrödinger’s day, neither mathematics nor physics provided any genuine support for the idea. There were no tools for analyzing irregularity as a building block of life. Now those tools exist.”
And Erwin Schrödinger was exceptional in so many ways, a great physicist and a great philosopher, responsible for much of the research that goes on in physics today, and who still lives among us with his discoveries, knowledge and also in the fate of his unfortunate cat!