Wave-particle dualism

Wave-Particle-Dualism
The wave-particle duality is a theory of quantum physics, according to which all matter exhibits the attributes of waves and particles.


 * Classical waves propagate in space. They weaken or strengthen by superposition and can act simultaneously at different locations with different strength.


 * A classical particle can be present at a specific location only at one time. It acts only there but always with all it’s charge, energy, impuls etc.

Both properties seem to contradict each other. Nevertheless, it was shown in several experiments that both properties are present. Therefore it is impossible to create a concrete image of the wave-particle duality, which is based on our classical perspectives. Depending on the type of measurement that is performed light can occur either as a wave or a particle, but never both at the same time.

The Double-Slit Experiment
Experiment setup The behavior of quantum objects is especially shown in the so-called double-slit experiment. Thomas Young was the first to demonstrate the wave nature of light with this experiment.

Experiment setup

Rays are sendt out from a source, either electromagnetic waves or particles of matter, and meet a panel with two very fine, closely spaced slits. This diaphragm is called the "double slit". Behind the panel is a screen. The rays are passing through the double slit, apply to the screen and are registered there.

Behavior of classical waves

If it is in the beam to classical waves a characteristic interference pattern is observed, very similar to the pattern resulting from the interference of water waves.

Behavior of particles

Particles do not interfere, they either get through the left or right gap and then appear within a clearly defined area on the screen.

Bahavior of light

The wave nature of light causes the light waves passing through the two slits to interfere, producing bright and dark bands on the screen—a result that would not be expected if light consisted of classical particles. The double slit experiment shows that matter has properties of matter only when a measurement takes place. If there is no information about the particle, there is a propability of its stay. As long as we have no information through which slit the particle flies, the particle shows no matter property. Matter properties are observed only when information about the particles are present so it only behaves as a particle during observation. This leads to the conclusion that the observer plays a crucial role in whether matter as such is existent or not.