The double-slit experiment is a famous demonstration of the wave nature of light, first performed by Thomas Young in 1801. Here's how it works: A coherent light source, such as a laser, is directed at a barrier with two closely spaced slits. Behind the barrier, there's a screen to capture the light passing through the slits. If the light is directed at the screen without the slits, you would see a bright spot where the light hits. If the light passes through only one slit, you'd see a single band of light on the screen directly in line with the slit. When the light passes through both slits, something interesting happens. Instead of two bright spots, you see a pattern of alternating bright and dark bands called interference fringes. This pattern is created because light waves from the two slits interfere with each other.

Since then, it has been suggested that conducting the same experiment with electrons yields similar results, indicating that electrons behave like electromagnetic waves of light. However, this proposal presents a couple of issues. Notably, there appears to be no clear description of how this experiment is conducted. What is often overlooked is the necessity of performing the experiment in a vacuum, and there is no evidence or record of the double-slit experiment ever being carried out under such conditions. The only experiment of this nature performed in a vacuum was the Stern Gerlach experiment which itself was not a double slit experiment.

The standard way this experiment is conducted typically involves two slits. However, an interesting question arises: what happens if the two slits are removed, leaving only the thin central obstruction? The outcome can be observed by performing a simple experiment using a laser pointer, a thin filament, and a white wall, as demonstrated below.