ERWIN SCHRODINGER

Erwin Schrödinger 1887-1961

Erwin Rudolf Josef Alexander Schrodinger was an Austrian physicist born in Vienna August 12, 1887.
He was awarded with Paul Dirac, the Nobel Prize for Physics in 1933 for the wave equation called the Schrödinger equation. It is a physicist at the origin of quantum physics.
Known also for the astonishing thought experiment, Schrodinger's Cat (see below), following a correspondence with Albert Einstein in 1935.
He received his doctorate in theoretical physics at the University of Vienna in 1910.
In 1914, Erwin Schrodinger participates in the First World War as an artillery officer.
In 1926, Schrodinger published an article in the Annals of Physics of the problem of quantization of the eigenvectors, which becomes the Schrödinger equation.
In 1933, Schrodinger left Germany and went to England, because of Nazism and antisemitism.
At Oxford University, he received his Nobel Prize.
In 1936, Schrodinger returns to Austria, at the University of Graz.

NB: In quantum mechanics, it is not possible to know exactly the value of a parameter without measuring. The mathematical theory describes a state not by a torque, speed and position precisely, but by a wave function that calculates the probability of finding the particle at a point.
Hence the probabilistic nature of quantum mechanics who predicted that the particles are also waves and only material points.

"I was born into an environment, I do not know where I came or whither I go or who I am. This is my situation like yours, to each of you.
The fact that each man has always been in this situation and there will always teaches me nothing.
All we can observe ourselves about the burning questions about our origin and destination, this is the environment. That is why we are eager to find about him all we can.
TThis is what science, knowledge, knowledge that is what is the real source of all spiritual effort of man.
We try to discover what we can about the spatial and temporal context in which we were born we were located.
And in this effort, we find joy, we find it extremely interesting (even if not the purpose for which we are here?)".
"The isolated knowledge obtained has a group of specialists in a narrow field has in itself no value whatsoever, it has value only in the synthesis which brings to the rest of the knowledge and only insofar as it really contributes in this synthesis, to answer the question: Who are we?"
Erwin Schrodinger (From his conferences).

Image: Who are we? Erwin Schrodinger

Schrödinger's cat

The observer changes what is observed!
Some events happen only because they are observed, if there was nobody to see them they would not exist.
This is the very meaning of the experience known as "Schrödinger cat".
In 1935 the physicist Erwin Schrodinger imagined a cat with an experience of the real world, enclosed in an opaque box and sealed. In this box a device kills the animal when it detects the decay of an atom of a radioactive body of the quantum world.
In the quantum world a radioactive atom for example, a uranium atom can exist in two superposed states: intact and disintegrated.
This superposition state ceases immediately when there is observation, we say that there is decoherence when a system A and B becomes an A or B.
If the probabilities indicate that disintegration has an even chance of having occurred after one minute, quantum mechanics states that, as the observation is not made, the atom is simultaneously in two states: intact and disintegrated. But the diabolical mechanism, devised by Erwin Schrodinger, the cat's condition is binding on the state of radioactive particles, so the cat is simultaneously in two states (the state of live and dead), until opening of the box.

As the observation triggers the choice between the two states, you simply can not tell if the cat is dead or not after one minute.
Our brain is not ready to accept this situation for a macroscopic object in the real world, while for a particle, the mind accepts to design what the wave function result.
Historically, the wave function was introduced by Louis de Broglie in his thesis in 1924.
His name is explained by the fact that it gives every particle, the interference properties of a wave, generalizing the wave-particle duality for light introduced by Max Planck.
This is not feasible a pure thought experiment because you can never measure, the cat is both dead and alive, the fact of trying to know its status necessarily cause the collapse of the wave function, inseparable of two distinct states.
These superposed states are conceivable when the systems are defined by wave functions.
But with regard to Schrödinger's cat, our mind refuses to admit that until the box is not open, and we did not observe the state of the cat, the cat is neither dead nor alive.

Image: Illustration © Mylène Simoès, Art Director.
Where does the choice of cat for this thought experiment? Perhaps this is a reference from Schrödinger, at Cheshire cat.