NarratorNow listen to part of a lecture in a physical science class.Male ProfessorSo, in the early twentieth century, there was this big debate going on in the scientific community. Did very small stuff like electrons behave like particles? Or did electro

Narrator

Now listen to part of a lecture in a physical science class.

Male Professor

So, in the early twentieth century, there was this big debate going on in the scientific community. Did very small stuff like electrons behave like particles? Or did electrons, these negatively charged things that whirled around the nucleus of the atom…did these electrons actually behave like SOMETHING ELSE? For a long time, it was assumed that because electrons were DISCRETE… I mean, because electrons seemed to be individual objects with specific energy levels…for a long time, it was assumed that electrons were simply small particles.

But then the double slit experiment happened. In the double slit experiment, electrons are shot at a screen containing two long, vertical holes. The positions of the electrons after they go through the screen are captured on film. Experimenters expected that the results of the experiment would be simple. Because they thought that electrons were like small particles… uhh, they guessed that the electrons that went through the two slits would create a pattern of two narrow bands, or lines, on the film.

However, this is not at all what the experimenters saw. Instead, they were shocked that the electrons formed an INTERFERENCE PATTERN, one by one, on the film. In other words, the electrons randomly scattered all over the film in a wave-like pattern instead of collecting in two narrow bands and creating the pattern that PARTICLES would make.

So, the double slit experiment was significant because it forced scientists to RETHINK the nature of electrons. They realized that electrons, like light, have characteristics of both particles and waves. Like particles, they collected one by one on the film. But like waves, they formed a complex INTERFERENCE PATTERN on the film instead of forming two neat lines. The results of the experiment…they’re discussed, debated, and reproduced to this day.