I understand how a wave create the interference pattern, but what is the mechanism for a single electron after it pass the slit and scatter and land at different location on the screen to produce the same interference pattern.

Does the electron pass through one slit or it split into two before the slit and pass through both the slit?


  • $\begingroup$ Neither. There are multiple versions of the electron, see "The Fabric of Reality" by David Deutsch, chapter 2. $\endgroup$ – alanf Nov 7 '19 at 9:21
  • $\begingroup$ The electron goes through one slit but its being accelerated by different sources throughout the trajectory. Accelerated electrons emit millions of photons in random directions, which reflect back and interact with the traveling electron constantly until it impacts the screen. It would be identical to a wave function but have a real origin. $\endgroup$ – Bill Alsept Nov 10 '19 at 3:02

Nobody can say what 'really' happens. However, quantum theory says that the wave function associated with the electron passes through both slits and interferes with itself, producing areas of higher and lower probability for the electron to be detected. Whether the electron itself is wavelike, and passes through both slits before collapsing to a point at the detector, or whether the electron is guided through one or other slit by the wave function is still a matter of debate about which interpretation of quantum theory applies.

  • $\begingroup$ If the electron is itself a wavelike, then why would it land at one spot at one time, shouldn't it produce the wavelike interference pattern as a whole? Also if the electron passes through say one of the two slit, why would it scatter away from the straight path? $\endgroup$ – Rajesh Marndi Nov 7 '19 at 9:34
  • $\begingroup$ Hi Rajesh. Again, nobody knows. In some circumstances the electron seems to behave like a wave; in others it behaves as a point like particle. If you Google 'wave-particle duality' you will find countless articles about it. There are various 'interpretations' of quantum theory that try to explain the phenomenon is different ways. If you want to become famous, you might try to find a rock solid explanation that can be tested by experiment. $\endgroup$ – Marco Ocram Nov 7 '19 at 10:25
  • $\begingroup$ The electron is wave-like, but interactions always occur at a point. $\endgroup$ – garyp Nov 7 '19 at 18:05
  • $\begingroup$ @rajesh Simple conservation of energy guarantees a single electron “producing the entire interference pattern” can’t happen; you need multiple electrons to see that. Why? Think about what the spot on your detection plate is: the electron excites one of the atoms in the detector, which releases a photon, and you see that as a mark on your plate. Since energy levels within atoms are quantized, something like “1/100th of an electron’s energy” isn’t going to be able to excite the atoms in the detector. You need a full quanta of the electron field to interact, and thus see your detection. $\endgroup$ – JPattarini Nov 10 '19 at 1:28
  • $\begingroup$ The mystery in the double slit experiment isn’t “why don’t single photons/electrons produce the whole pattern” since to excite that many atoms in your detection plate obviously takes more than a single electron (no one seems surprised that one electron doesn’t ionize 200,000 atoms in other scenarios!). $\endgroup$ – JPattarini Nov 10 '19 at 1:31

The electron doesn't really interfere with it self but it act as if it does so by avoiding regions with destructive interference and hitting the screen where it should when it would constructively interfere with its hypothetical self coming from the other slit, thus, there is a higher probability of it hitting the screen on a bright region consistent with a constructive interference of an interference patern than it hiting it on a dark region of that pattern and this means that every single electron that passes through the slits will hit the screen and it will not disappear (in the case of a complete destructive interference ) instead it avoids angeles of destructive interference .....


All matter has both wave and particle properties, for small particles it is possible to observe the wave properties. For massive particles it is impossible to observe the wave properties, the theoretical wavelength is too short. The reason particles have wave properties is because all matter interacts with each other thru the EM field, i.e when a particle is colliding with another the electrons are the first to "see" or "sense" each other (there is something called virtual photons). Because the interaction is in the EM it has to have a wavelength/wavefunction associated with it. The term interference is historical, the slit experiment for photons showed a pattern similar to what water waves do. Even single photons "interfere" but it is better to think of an allowed path explanation (Feynman) where the brights spots occur. The electron will choose one slit at random, with this new path it will look to interact with the screen at a point that works with its wave function, this causes the INTENSITY pattern (note: I did not want to use the word "interference"!):


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