Whilst going through 'A brief history of time', I faced difficulty in understanding the two slit experiment. How can an individual electron cause fringes on screen? I was unable to understand it? Please explain it simply.

  • $\begingroup$ One electron produce a single spot on the screen. You get fringes only when many electrons past. However, there are no interactions between electrons. To explain why that happens is very difficult and there are many interpretations. One of them is the Many-World interpretation. $\endgroup$
    – freude
    Commented Apr 5, 2016 at 15:32
  • $\begingroup$ That why has been teasing me brother $\endgroup$ Commented Apr 5, 2016 at 15:35
  • 1
    $\begingroup$ The interference pattern that appears even with only one photon passing through the setup at any time was the exact cause of the acceptance of the wave theory of light. That electrons behave the same implies they can't be thought of as particles in the classical sense. This has been asked in some form or another many times. $\endgroup$
    – G_H
    Commented Apr 6, 2016 at 10:54
  • $\begingroup$ Questions and their answers of interest: physics.stackexchange.com/questions/238855/… physics.stackexchange.com/questions/35328/… $\endgroup$
    – G_H
    Commented Apr 6, 2016 at 11:01

1 Answer 1


As far as I understand the two slit experiment one explaination is superposition, 'cause when they just observed the screen the electrons acted like a wave, not just hitting one spot but hitting all spots with varying intensity (which is what created all the lines), but when they tried to track individual electrons they just hit one spot. The conclusion that they drew (one of them, as said in the comments the many-world is another slightly different interpretation of superposition) was that when unobserved, the electrons went down every possible path, just like a wave would.

Hope I could help


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