When was uncertainty principle discovered

Most of the young men who created matrix mechanics were ready to move into teaching positions as professors, and the older generation of theoretical physicists was beginning to vacate positions at German universities. Heisenberg's family was exerting pressure on the young man to capture one of the vacancies at the same time that his best work, matrix mechanics, seemed to be overshadowed by wave mechanics.

The intense debates in Copenhagen proved inconclusive. They showed only that neither interpretation of atomic events could be considered satisfactory. Both sides began searching for a satisfactory physical interpretation of the quantum mechanics equations in line with their own preferences. The task then became a search for the physical meaning of these equations in actual situations showing the nature of physical objects in terms of waves or particles, or both.

As Bohr later explained it, events in tiny atoms are subject to quantum mechanics, yet people deal with larger objects in the laboratory, where the "classical" physics of Newton prevails. What was needed was an "interpretation" of the Dirac-Jordan quantum equations that would allow physicists to connect observations in the everyday world of the laboratory with events and processes in the quantum world of the atom.

Studying the papers of Dirac and Jordan, while in frequent correspondence with Wolfgang Pauli, Heisenberg discovered a problem in the way one could measure basic physical variables appearing in the equations. In fleshing out this radical worldview, Heisenberg discovered a problem in the way that the basic physical properties of a particle in a quantum system could be measured.

In one of his regular letters to a colleague, Wolfgang Pauli, he presented the inklings of an idea that has since became a fundamental part of the quantum description of the world. The uncertainty principle says that we cannot measure the position x and the momentum p of a particle with absolute precision.

The more accurately we know one of these values, the less accurately we know the other. Multiplying together the errors in the measurements of these values the errors are represented by the triangle symbol in front of each property, the Greek letter "delta" has to give a number greater than or equal to half of a constant called "h-bar".

Planck's constant is an important number in quantum theory, a way to measure the granularity of the world at its smallest scales and it has the value 6.

One way to think about the uncertainty principle is as an extension of how we see and measure things in the everyday world.

You can read these words because particles of light, photons, have bounced off the screen or paper and reached your eyes. Each photon on that path carries with it some information about the surface it has bounced from, at the speed of light. Seeing a subatomic particle, such as an electron, is not so simple. You might similarly bounce a photon off it and then hope to detect that photon with an instrument. But chances are that the photon will impart some momentum to the electron as it hits it and change the path of the particle you are trying to measure.

Or else, given that quantum particles often move so fast, the electron may no longer be in the place it was when the photon originally bounced off it. The layman without knowledge of higher mathematics, listening to Dr. Heisenberg and those who discussed his conclusions, would have decided that this particular section of the British Association is composed of quiet and polite but determined lunatics, who have created a wholly illusory mathematical world of their own.

To explain the quantum theory and its modification by Dr. Heisenberg and others is even more difficult than explaining relativity. It is much like trying to tell an Eskimo what the French language is like without talking French. In other words, the theory cannot be expressed pictorially and mere words mean nothing. One is dealing with something that can be expressed only mathematically. The consequences, however, are startling.

Electrons and atoms cease to have any reality as things that can be detected by the senses directly or indirectly. Why is the Heisenberg uncertainty principle not significant when describing macroscopic object behavior? See all questions in Heisenberg Uncertainty Principle. Impact of this question views around the world. You can reuse this answer Creative Commons License.