# Uncertainty principle and double slit

• Harshall
In summary, the conversation discusses the possibility of using Heisenberg's uncertainty principle to explain the double slit experiment. While it may provide a heuristic explanation for diffraction, it is not able to fully explain the interference patterns observed. Instead, a combination of the uncertainty principle and superposition principle may provide a more elegant explanation for the phenomena.
Harshall
sir, what if we use Heisenberg's uncertainty principle to explain double slit experiment?
i was reading about uncertainty principle for last few days n i was reading about double slit experiment and i realize that we can explain why we get electrons everywhere on the screen (getting interference i think can be explained using wave function or something similar to it which will be a mathematical model) rather then getting 2 bands... as we are using narrow slits we can find position of electron wid accuracy which results in uncertainty in momentum..as width of the of the slit is narrow bt nt height which implies uncertainty in momentum in the direction the width increases.

That works as a heuristic explanation for diffraction (the beam spreads out after the slit, and the narrower the slit the greater the spread) but not for interference (dark and light bands appear in the region of overlap when there are two slits).

However, diffraction and interference can be calculated directly from the wave function without appealing to the uncertainty principle, so that may be a better starting point for the explanation of both phenomena.

An interesting question. In a similar way to how confinement in a well leads to quantisation, does confinement in space in slots perpendicular to the beam lead to the quantisation of the momentum in the perpendicular direction?

Harshall said:
sir, what if we use Heisenberg's uncertainty principle to explain double slit experiment?

By itself it can't explain it.

I personally don't like the usual wave-particle explanation because as you progress in QM you find its basically a myth:
http://arxiv.org/pdf/quant-ph/0609163.pdf

A much better explanation (still not perfect though - even it has issues) combines the uncertainty principle and superposition principle in a very elegant way:
http://arxiv.org/ftp/quant-ph/papers/0703/0703126.pdf

Thanks
Bill

cobalt124 and Mentz114

## 1. What is the uncertainty principle?

The uncertainty principle, also known as Heisenberg's uncertainty principle, is a fundamental concept in quantum mechanics. It states that the more precisely we know the position of a particle, the less precisely we can know its momentum, and vice versa. This means that there is a limit to how accurately we can measure certain properties of particles at the same time.

## 2. How does the uncertainty principle relate to the double slit experiment?

In the double slit experiment, a single particle is fired towards two parallel slits. The resulting pattern on the screen behind the slits shows interference, indicating that the particle behaves like a wave. This experiment demonstrates the wave-particle duality of particles. The uncertainty principle comes into play because the act of measuring which slit the particle goes through disrupts the interference pattern, as it requires knowledge of both the position and momentum of the particle.

## 3. Can the uncertainty principle be violated?

No, the uncertainty principle is a fundamental principle of quantum mechanics and has been experimentally verified numerous times. It is a fundamental limitation of our ability to measure certain properties of particles simultaneously.

## 4. How does the uncertainty principle impact our understanding of the physical world?

The uncertainty principle challenges our classical understanding of the physical world, where we expect to be able to measure and predict the behavior of particles with absolute precision. It also highlights the limitations of our current scientific theories and the need for a more comprehensive understanding of the quantum world.

## 5. Are there any practical applications of the uncertainty principle?

Yes, the uncertainty principle has practical applications in various fields, such as quantum computing and cryptography. It also plays a crucial role in technologies such as MRI machines and electron microscopes, where the uncertainty principle is used to produce detailed images of tiny particles.

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