# Basic Double Slit Question

• PatrickPowers
In summary, in double slit systems, the intensity of the "particle" source does not affect the interference pattern. This means that even if only one particle is present, it will still interfere with itself. However, when multiple particles are in the system, their repulsion can blur the pattern. The phase of the electron in the quantum wavepacket is what determines interference, not the electron itself. Feynman's lectures on wave-particle duality provide a deeper understanding of this concept.

#### PatrickPowers

So I read that in double slit systems the intensity of the "particle" source does not matter. If it is known that only one particle is in the system at a time, the interference pattern will be the same as observed when there are multiple particles in the system. From this we can conclude that the particle is interfering with itself.

What puzzles me is this. Let;s say we have multiple electrons in the system. Shouldn't they repel one another and hence blur the interference pattern? Even if they didn't repel one another, wouldn't the phase of one electron be random with respect to the phase of any other, and this would eliminate the interference pattern except for the case of the electron interfering with itself.

So I have something wrong here. What is it?

electrons in a beam do repel each other and that does blur the image. A lot of effort goes into focussing and guiding the beam. Notice that CRT TVs are capable of quite good electron placement over meter-lengths.

the "phase" is in the quantum wavepacket not the "electron" - this is where we need to be careful about what we are talking about.

Feynman did a series of lectures on wave-particle duality and explains the relationship quite well.
... see the whole lecture series. It's worth it.

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## What is the basic double slit experiment?

The basic double slit experiment is a fundamental experiment in physics that demonstrates the wave-particle duality of light. It involves shining a coherent light source, such as a laser, through two parallel slits and observing the resulting interference pattern on a screen.

## Why is the double slit experiment important?

The double slit experiment is important because it provides evidence for the wave-particle duality of light, which is a fundamental concept in quantum mechanics. It also serves as a basis for many other experiments and theories in physics.

## What does the double slit experiment demonstrate?

The double slit experiment demonstrates that light behaves as both a particle and a wave. When observed through the slits, light behaves like a wave and creates an interference pattern. However, when observed at the screen, it behaves like a particle and forms distinct points of impact.

## What are the applications of the double slit experiment?

The double slit experiment has applications in various fields such as optics, quantum mechanics, and even biology. It is used to understand the behavior of light and other particles, and has led to advancements in technologies such as holography and diffraction gratings.

## Are there any variations of the double slit experiment?

Yes, there are variations of the double slit experiment that involve different types of particles, such as electrons or even larger molecules. These variations continue to provide evidence for the wave-particle duality of matter and have implications in fields such as nanotechnology and quantum computing.