Applications of

Quantum Physics

Quantum Physics

Implications of

Quantum Physics

Quantum Physics

34. Scattering Experiments.

Summary

A typical scattering experiment is to ‘bounce’ an electron off a proton. It might seem that particles are needed to explain scattering experiments, where only one detector out of many hit by the scattered wave function is activated. But the results can be explained using only the properties of the wave function.

Scattering experiments such as those done at the Large Hadron Collider are the main means of gaining information about ‘particles’ on the sub-atomic level. One ‘particle’ (particle-like wave function) is shot at another and the way it bounces off tells something about the two particles and their interactions. The interesting point here is that it

*appears*particles are necessary to understand the results. But we can use reasoning which is virtually identical to that in the Localization section to show that particles are not required for the explanation.

To illustrate, suppose we have a target proton surrounded by a sphere coated with film grains on the inside. An electron (electron-like wave function) is shot at the proton and the wave function of the electron spreads out in all directions, hitting every grain. But a microscopic examination will show that on a single run, one and only one grain is exposed. As in the case of light, it is

*as if*a particulate electron embedded in the wave function followed a particular trajectory and hit and exposed only one grain.

But it is not necessary to assume the existence of particles. The result can be explained purely quantum mechanically, as is done in Quantum Mechanical Details of Scattering.