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Ray McDavis
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Waves are energy moving. Light is moving packets of fixed amounts of energy. Why must we invoke particles to understand light? How is a wave (energy moving) antithetical to packets of energy?
Because when we detect low intensity light, we always detect discrete events. For example, in a double slit experiment, if you run it with the light intensity fairly high, an interference pattern will appear on the detector screen, but as you turn the light intensity down further and further, you don't see the complete pattern all at once but fainter and fainter. You see the pattern resolve into individual dots that hit different points on the screen at random times, and the interference pattern gets built up over time by the dot impacts.Ray McDavis said:Why must we invoke particles to understand light?
It was Einstein's explanation for the photoelectric effect that began the quantised theory of light:Ray McDavis said:Waves are energy moving. Light is moving packets of fixed amounts of energy. Why must we invoke particles to understand light? How is a wave (energy moving) antithetical to packets of energy?
Ray McDavis said:Waves are energy moving. Light is moving packets of fixed amounts of energy. Why must we invoke particles to understand light? How is a wave (energy moving) antithetical to packets of energy?
Ray McDavis said:Waves are energy moving. Light is moving packets of fixed amounts of energy. Why must we invoke particles to understand light? How is a wave (energy moving) antithetical to packets of energy?
MRMMRM said:According to this picture ... consists of a finite number of energy quanta that are spatially localized at points of space,
Photons are a fixed delta in space or time, "
PeroK said:
Unfortunately, what you say is not correct. Photons are not localized in space, although they are the quanta of the quantized Electromagnetic field. See, for example:
https://www.physicsforums.com/threads/why-no-position-operator-for-photon.906932/
These two statements are mutually inconsistent. Speed is defined as the magnitude of the velocity and velocity is defined as the change of position with time, so if we can’t assign a definite position to a photon we can’t define its speed either (although the momentum of a photon is OK because we have a definition other than the the classical ##p=mv##).MRMMRM said:Photons are moving at a constant speed, and you can't give them a single defined position
Planck's law is about thermal radiation in a cavity. In a cavity the photons, i.e., the normal modes, are not localized at all, because they are standing waves.MRMMRM said:Plancks law, sure does descibe black body radiation nicely. It doesn't ignore position, but ensures that it's defined.
Frequency and momentum are the same thing.
Photons are moving at a constant speed, and you can't give them a single defined position, other wise they would cease to exist. Just like if a moving mass stopped, its momentum would cease to exist. That doesn't mean the energy or mass are not localized in space. Thinking of them as a particle occuping a volume of space is ok, just know that, that energy is never stationary or accelerating while it exist as a photon.
Then if you wanted to know a photons "inertia" or "moment of inertia" if you think of them as spinning, well I would say that is Plancks constant.
The wave-particle duality of light refers to the fact that light exhibits both wave-like and particle-like behavior. This means that in some experiments, light behaves like a wave, while in others it behaves like a stream of particles called photons.
Light exhibits wave-like behavior through phenomena such as diffraction, interference, and polarization. These behaviors can be explained by the wave nature of light, as described by the electromagnetic wave theory.
Light waves have properties such as wavelength, frequency, and amplitude. They can also travel through a vacuum at the speed of light, and can be reflected, refracted, and diffracted.
Light behaves like a particle in that it can be emitted and absorbed in discrete packets of energy called photons. These photons have a specific energy and momentum, and can interact with matter in a particle-like manner.
The photoelectric effect, Compton scattering, and the double-slit experiment are all experiments that demonstrate the particle nature of light. These experiments show that light can behave like a stream of particles, rather than a continuous wave.