Double Slit Experiment


One of the experiments that led to the acceptance of wave-particle duality is the double slit experiment. Wave-particle duality is the confusing explanation that particles, including light, can be expressed not only in terms of being a particle but also a wave. Conveniently, a quantum object can sometimes exhibit particle behavior and sometimes wave behavior.

The double slit experiment first showed this property for light. In the experiment, light is shone through a slit in the first object such that it can proceed through to a second object. It can be done with a simple flashlight, a piece of paper with one hole/slit cut into it, and a wall behind it. The light captured on the wall will match the slit pattern in the paper. However, if a second slit is cut in the paper, it shows a diffraction pattern, because of wave interference from the light passing through both slits.

The double slit experiment first showed that light had both properties of a wave and a particle. However, as explained in Photons, it has been explained that light does travel in packets, or photons, and is not a continuous wave, although it carries transverse and longitudinal traveling wave components described earlier in the Photon section. It is quantized.

The double slit experiment was also conducted on particles, like the electron, and similar results were obtained. The electron, thought to be a particle, also produced the same diffraction pattern. The electron and other elementary particles are currently also considered to have wave and particle characteristics – wave-particle duality. When one slit is open the electron behaves like a particle. When the second slit is open, the electron produces a diffraction pattern resembling a wave pattern. If a measuring device is placed on the second slit to determine if the electron passes through the slit, it reverts back to the same result as if one slit was open – no diffraction pattern is found.


Double Slit Experiment Results




An illustration to provide this explanation is shown below. Particles consist of wave centers that can be measured to have a definitive position in space and time. These same particles, such as the electron, also generate standing waves of energy and beyond the particle’s radius, traveling waves. This was modeled in the Longitudinal Energy Equation. It’s better to think of the electron as a particle, but one that reflects a wave and is affected by wave amplitudes of all particles, including itself, if it interacts with its own wave that has traveled through a second slit. The path of the electron being affected by its own traveling waves is illustrated in the figure. Note the electron does not go through both slits. It is a particle and can only go through one slit.

Double Slit Experiment

Double Slit Experiment

If a measuring device is placed on one of the slits, it has the potential to affect the traveling wave generated by the electron. Cancelling or disrupting this wave causes the change in the motion of the electron. If its traveling waves through the second slit are cancelled with destructive wave interference, then the electron would have a motion similar to the single slit experiment.

Light is a wave, but travels in a discrete packet known as the photon. It is not a particle defined in this theory as containing wave centers.

The electron is a particle as it contains wave centers that reflect in-waves to out-waves, thereby creating standing waves of energy. Beyond the particle’s definition (radius), its out-waves are longitudinal traveling waves.