Under what conditions is a photon a particle?

In summary, the conversation discusses the Wheeler experiment in Australia and the behavior of a photon passing through two slits. The question arises of how the photon is measured if the screen is removed after it has passed through. The response explains that the measuring device is destroyed, and the concept of wave-particle duality is dismissed as a "crock." Instead, it is suggested to view the photon's behavior in terms of momentum rather than position. The conversation also touches on the difficulty of getting light to behave as a particle due to its unique properties.
  • #1
jimmylegss
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I read about the wheeler experiment been done in Australia. But one thing I don't understand. If the particle (but let's use a photon) goes through the two slits (or one) and the screen is removed after it already went through, how is it measured?

Does it stop after the measurement? My understanding is that when the photon hits the final screen and has no more to go it shows as a wave pattern. But when it interacts when it has still some way to go, it is a particle? So is it sort of hit by other light beams to see what slit it went through along the way to the screen?

Let's take visible red light for example, under what conditions can it interact and behave like a particle? And why is it so difficult to get light to behave as a particle?

Thanks!
 
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  • #2
jimmylegss said:
I read about the wheeler experiment been done in Australia. But one thing I don't understand. If the particle (but let's use a photon) goes through the two slits (or one) and the screen is removed after it already went through, how is it measured?!

So your question is if the measuring device, the screen, is removed, how is it measured? Easy - it inst. So?

jimmylegss said:
Does it stop after the measurement?

Its usually destroyed by measurement.

jimmylegss said:
My understanding is that when the photon hits the final screen and has no more to go it shows as a wave pattern. But when it interacts when it has still some way to go, it is a particle? So is it sort of hit by other light beams to see what slit it went through along the way to the screen?

Forget this wave particle stuff - its a crock. Here is the correct explanation:
http://arxiv.org/ftp/quant-ph/papers/0703/0703126.pdf

jimmylegss said:
Let's take visible red light for example, under what conditions can it interact and behave like a particle? And why is it so difficult to get light to behave as a particle?

It never is a particle in a usual sense because for photons position is not an observable. As the link above explains the screen at the back measures momentum.

Thanks
Bill
 
Last edited:

1. What is a photon?

A photon is a fundamental particle that is the smallest unit of light. It is the basic unit of electromagnetic radiation and is responsible for carrying energy in the form of light.

2. How can a photon be both a particle and a wave?

According to quantum mechanics, particles can exhibit wave-like properties and vice versa. Photons exhibit both particle-like behavior, such as having a definite energy and momentum, and wave-like behavior, such as interference and diffraction.

3. Under what conditions does a photon behave as a particle?

A photon behaves as a particle when it interacts with matter. This means that it has a definite position and momentum and can be absorbed or emitted by matter.

4. Under what conditions does a photon behave as a wave?

A photon behaves as a wave when it is traveling through space. This means that it exhibits properties such as diffraction and interference, and does not have a definite position or momentum.

5. How do we know that photons are particles?

The particle nature of photons has been confirmed through various experiments, such as the photoelectric effect and Compton scattering. These experiments have shown that photons have discrete packets of energy and can act as individual particles in interactions with matter.

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