# How an electromagnetic amplitude becomes QM probability?

1. Aug 25, 2014

### luisgui

At the core of the quantum concept by Planck was the black-body radiation, then: electromagnetic waves, whose amplitudes are electric and magnetic fields, but when one follow the developments and one comes to the Schrödinger waves, now their amplitudes are not of that kind but related to probability of finding a particle at a given point. How is that change possible?
So, does an electromagnetic wave (for example in the ultraviolet range) simultaneously have a probability-related wave?

Thank You.

2. Aug 25, 2014

### Delta²

No the wave function in the Schrodinger equation has nothing to do with EM-waves. The wave function does not represepent a field that exists in the physical reality (like the EM field or the gravitational field) , the wave function is just a mathematical object that give us information about the position or the momentum of a particle.

What i said is the Copenhagen interpretation of the wave function that is widely accepted by the scientific community.

3. Aug 25, 2014

### atyy

For particles, the usual Schreodinger wave function is a function of particle position, and allows one to calculate proibabilities for particle observables for like position or momenta.

Roughly, for the electromagnetic wave, the Schroedinger wave function becomes a function of field configuration, and allows one to calculate the probability for field observables. http://en.wikipedia.org/wiki/Schrödinger_functional

But it is very hard to use, and I think quantum field theory in the Schroedinger functional approach is not so well worked out. Usually people use a different language called second quantization, and describe the state space as a Fock space.

Last edited: Aug 25, 2014
4. Aug 25, 2014

### luisgui

Thank you, Delta and atyy.
This becomes somewhat more clear now to me.

5. Aug 25, 2014

### kith

It is not without issues but the electromagnetic field can be viewed as the wavefunction of a single photon. Search for "photon wavefunction" here or on the web.