Why waves of light don't hit each other?

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    Light Waves
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Discussion Overview

The discussion centers on the interaction of light waves, particularly focusing on whether they can "hit" each other, how they overlap, and the implications of their wave and particle properties. Participants explore concepts related to interference, the nature of photons, and comparisons with other types of waves, such as water waves and sound waves.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that light waves interfere rather than collide, leading to constructive and destructive interference patterns.
  • Others argue that waves simply overlap, with the total electromagnetic field being the sum of the individual waves.
  • A participant mentions that photon-photon scattering is theoretically possible at high intensities, though it has not been observed.
  • There is a discussion about the nature of photons, with some participants questioning how photons can pass through each other if they have particle-like properties.
  • Concerns are raised about how light waves can alternate without a medium, contrasting them with water waves that are influenced by gravity.
  • Participants discuss the photoelectric effect, emphasizing that light interacts in discrete energy packets called photons.

Areas of Agreement / Disagreement

Participants express differing views on the nature of light waves and photons, with no consensus reached on how to reconcile their wave and particle characteristics. The discussion remains unresolved regarding the implications of these properties on interactions between light waves.

Contextual Notes

Some participants highlight the complexity of explaining the behavior of light waves and photons, noting that certain aspects, such as the mathematical underpinnings of electrodynamics, are not easily addressed without further detail.

aiop
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How do waves interact, What happens when two waves with the same frequency and wave length hit each other. Would the resultant change if it was let's say an X-ray hitting an Gama-ray. That is if waves can even hit each other.
 
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No, they interfere, if that's what you want to call hitting. Do light waves scatter each other? I don't really know.
 
The waves simply overlap, with the total electromagnetic field being the sum of all the waves. If the waves have the same frequency, this can lead to regions of constructive and destructive interference, like in the double slit experiment.

Note that the same behavior is observed for other kinds of waves, like sound waves or waves at the surface of water.

For a very high intensity of light, photon-photon scattering is possible, but it has not yet been observed.
 
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DrClaude said:
The waves simply overlap, with the total electromagnetic field being the sum of all the waves. If the waves have the same frequency, this can lead to regions of constructive and destructive interference, like in the double slit experiment.

Note that the same behavior is observed for other kinds of waves, like sound waves or waves at the surface of water.

For a very high intensity of light, photon-photon scattering is possible, but it has not yet been observed.
But how can the waves simply over lap as well on water.
So if when describing light in waves they over lap, what about when describing light as a photon with particle light properties do they go straight through each other.
 
What is your envision of a photon?
 
aiop said:
But how can the waves simply over lap as well on water.
Why not?
Light is not made out of billard balls.
Photons do not even have a well-defined position.
 
256bits said:
What is your envision of a photon?
like a wave of water that also can have particle like properties. not sure how to tie that part into the image though, How could light with particle like properties just go through each other... i don't understand how that could be possible.
 
mfb said:
Why not?
Light is not made out of billard balls.
Photons do not even have a well-defined position.
But how can two different waves for example move through each other they don't have mass but are made out of energy and energy of two different levels if let's say a Gama-ray and a X-ray hit each other would they not have some reaction. When for example hot air moves through cold air they do react by transferring energy and that is just a matter of a difference in energy. so what makes light so special?
 
aiop said:
like a wave of water that also can have particle like properties. not sure how to tie that part into the image though, How could light with particle like properties just go through each other... i don't understand how that could be possible.

Light isn't a particle like a dust grain is a particle. It is not composed of solid pieces. It is simply alternating electric and magnetic fields. The "particle" property of light is that it interacts in discrete chunks of energy. There's literally no physical particles to imagine here, as you might imagine a water wave.
 
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Drakkith said:
Light isn't a particle like a dust grain is a particle. It is not composed of solid pieces. It is simply alternating electric and magnetic fields. The "particle" property of light is that it interacts in discrete chunks of energy. There's literally no physical particles to imagine here, as you might imagine a water wave.
But when imagining water to be like a light wave i run into a problem. Water waves go up and down because of gravity's pull so why would a light wave go up and down if light does not have mass. I know its alternating electric and magnetic fields but why would they behave as a wave without something to pull the waves making them waves and to cause them to alternate. How do light waves alternate?
 
  • #11
aiop said:
Water waves go up and down because of gravity's pull so why would a light wave go up and down if light does not have mass. I know its alternating electric and magnetic fields but why would they behave as a wave without something to pull the waves making them waves and to cause them to alternate. How do light waves alternate?

They don't go up and down. The electric and magnetic fields alternate in polarity and magnitude as the wave travels. As for why, well that's a consequence of electrodynamics and is not something easily explained without getting into the math.
 
  • #12
Haven't you ever watched water waves cross each other? Where "peaks" cross "peaks" the heights add, where "troughs" cross "troughs" they subtract but once they have passed on each leaves the other untouched.
 
  • #13
Drakkith said:
Light isn't a particle like a dust grain is a particle. It is not composed of solid pieces. It is simply alternating electric and magnetic fields. The "particle" property of light is that it interacts in discrete chunks of energy. There's literally no physical particles to imagine here, as you might imagine a water wave.
___________
then, how could photoelectric phenomenon be explained?
 
  • #14
Passionate Eng said:
___________
then, how could photoelectric phenomenon be explained?
You don't seem to have really read the post you are responding to. I'll repeat the significant part, relative to your question "The "particle" property of light is that it interacts in discrete chunks of energy."
 
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  • #15
Passionate Eng said:
___________
then, how could photoelectric phenomenon be explained?

Let's say that an EM wave with a wavelength of 198.6 nm interacts with the metal and transfers 1 joule of energy to the metal over the course of one second. If we were to look very closely, we would find that this energy was transferred to the metal in 1018 individual "bundles" or "chunks". Each of these bundles contained 10-19 joules of energy, no more no less. All of the energy was contained within these bundles and any EM wave with a wavelength of 198.6 nm would have a quantity of energy that is a multiple of 10-19 joules. These bundles are called photons.
 
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