Are there any energy change of photon in different frame?

In summary, photons can experience red or blueshift in different frames due to the Doppler effect, which is also used in astronomical calculations. The energy and momentum of photons transform between different frames through the Lorentz transformation, similar to how time and position transform. In the case of a photon, the energy is dependent on the relative velocity of the frames.
  • #1
ndung200790
519
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Please teach me about this:
Are there any change in energy and momentum of photon in different frame?Are there any analogies with Doppler effect?
Thank you very much in advance.
 
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  • #2
Yes! Indeed photons can be red or blueshifted, this doppler effect is how we do many calculations in astronomy (e.g. finding the speed of objects moving towards or away from us).
 
  • #3
Except for Doppler effect,are there any changing in energy-momentum of photon in different frame.Example:Consider Compton process in lab frame and center of mass frame.Because the frequence of photon in Doppler effect depends on the moving towards each other or far away of receiver and sourse
 
  • #4
Energy and momentum transform between different inertial reference frames exactly the same way as time and position, via the Lorentz transformation.

The time-position four-vector: (ct, x, y, z)

One way to write the energy-momentum four-vector: [itex](E, p_x c, p_y c, p_z c)[/itex]

If we need to deal only with x-components, the Lorentz transformation for time and position looks like this:

[tex]ct^\prime = \gamma (ct - \beta x)[/tex]

[tex]x^\prime = \gamma (x - \beta ct)[/tex]

For energy and momentum:

[tex]E^\prime = \gamma (E - \beta p_x c)[/tex]

[tex]p^\prime_x c = \gamma (p_x c - \beta E)[/tex]

where as usual [itex]\beta = v / c[/itex] and

[tex]\gamma = \frac{1}{\sqrt{1 - v^2 / c^2}} = \frac{1}{\sqrt{1 - \beta^2}}[/tex]

and v is the relative velocity of the two frames.

For a photon, E = pc, so the Lorentz transformation for the one-dimensional case becomes

[tex]E^\prime = \gamma (E - \beta E)[/tex]

[tex]E^\prime = \gamma (1 - \beta) E[/tex]

[tex]E^\prime = \sqrt {\frac {1 - \beta}{1 + \beta}} E[/tex]
 
Last edited:

1. What is the definition of energy change of photon?

The energy change of a photon refers to the difference in energy levels between the initial and final state of a photon. It is a measure of the amount of energy gained or lost by a photon during a physical process.

2. How does energy change of photon vary in different frames of reference?

According to Einstein's theory of relativity, the energy of a photon is relative to the observer's frame of reference. This means that the energy change of a photon can appear different depending on the observer's perspective.

3. Can the energy change of photon be negative?

Yes, the energy change of a photon can be negative. This occurs when a photon loses energy during a physical process, such as when it is absorbed by an atom or molecule.

4. What factors affect the energy change of photon?

The energy change of a photon is affected by several factors, including the wavelength and frequency of the photon, the speed and direction of the observer's frame of reference, and the presence of gravitational fields.

5. How is the energy change of photon related to the electromagnetic spectrum?

The energy of a photon is directly proportional to its frequency and inversely proportional to its wavelength. This relationship can be seen in the electromagnetic spectrum, where higher frequency waves (such as gamma rays) have more energy than lower frequency waves (such as radio waves).

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