String and EM Waves

Discuss the similarities and differences between the matter wave Ψ with (a) a wave on a string and (b) an electromagnetic (EM) wave.

Similarities
-Both waves in the string and EM are transverse. This means the oscillation plane is perpendicular to the direction of propagation.
-Both waves can be polarised. This means that it can exists a plane of preferential oscillation.
-Both waves are periodical in time and space. This means that there exists a time period and a space period after which the position indicated by both waves repeats itself.
-Both waves undergo the phenomena of reflection and refraction. This means that the speed of both waves changes in different propagation mediums.

Differences
– The string wave refers to the movement of physical particles. It is a position wave. It indicated the exact position in space of the particles contained in the string. The EM wave it is a probability wave. It indicates the probability of finding into a certain volume of space the particle named photon.
-For the string wave to exists it is necessary a medium of propagation (the string itself). For the EM wave to exists it is not necessary a medium of propagation (see the Michelson experiment).