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bernhard.rothenstein
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Many textbooks derive the formulas which account for the Doppler shift and for aberration of light from the invariance of the phase of an electromagnetic wave. Do you know an explanation for the invariance?
bernhard.rothenstein said:Many textbooks derive the formulas which account for the Doppler shift and for aberration of light from the invariance of the phase of an electromagnetic wave. Do you know an explanation for the invariance?
Thanks for your help. Your solution is of help. I put the following question (not statement)lightarrow said:I would explain it in this way, don't know how much correct it is: if I send n pulses of light or anything else (balls, objects, ecc.), I have to count exactly n pulses of it in every reference frame (I don't know how to call it; "invariance of the number of objects"?); in the same way I will have to count n maximums (for example) of an EM wave in every ref frame; this means that the phase of the EM wave must be invariant. I don't know how to formalize it better.
It's a good question. I have ever thought phase is a very important and deep concept in relativity and QM and so, maybe, it's one of the concepts that could link relativity to QM.
I would say no. For examplebernhard.rothenstein said:Thanks for your help. Your solution is of help. I put the following question (not statement)
Are the dimensionless combinations of physical quantities which appear at the exponent of e or in the argument of a trigonometric function relativistic invariants?
jtbell said:A wave's propagation vector [itex]\vec k[/itex] (whose magnitude [itex]k[/itex] is the wavenumber [itex]2 \pi / \lambda[/itex]) and frequency together form a four-vector:
[tex]k = (\omega / c, k_x, k_y, k_z)[/tex]
Position and time of course also form a four-vector:
[tex]r = (ct, x, y, z)[/tex]
Therefore their four-vector "dot product" is a Lorentz invariant:
[tex]k \cdot r = \omega t - k_x x - k_y y - k_z z = \omega t - \vec k \cdot \vec r[/tex]
lightarrow said:I would say no. For example
[tex]e^{i\omega t}[/tex] is not invariant, while
[tex]e^{i(\vec k \cdot \vec r - \omega t)}[/tex] is invariant.
The first paragraph on page 2 of arXiv:0801.3149v1 reads:bernhard.rothenstein said:Many textbooks derive the formulas which account for the Doppler shift and for aberration of light from the invariance of the phase of an electromagnetic wave. Do you know an explanation for the invariance?
A relatistic invariant must be a four-scalar.bernhard.rothenstein said:I rephrase my question
Are the combinations of physical quantities that appear in formulas that account for a real effect as arguments of e or of trigonometric functions relativistic invariants?
Example
radiactive decay exp(-t/T)
Plancks distribution law exp(-hf/kT)
and the phase of the e.m. wave in discussion.
Does your counter example account for something that hapens in nature?
Regards
Phase invariance refers to the property of electromagnetic waves where their amplitude and frequency remain constant, but their phase (the position of the wave in its cycle) can change without affecting their overall properties.
Phase invariance is important because it allows us to manipulate the phase of electromagnetic waves without altering their fundamental properties. This is useful in applications such as signal processing and telecommunications.
Phase invariance is closely related to the concept of superposition, which states that when two or more waves overlap, the resulting wave is the sum of the individual waves. Since phase invariance allows for the manipulation of wave phases, it also affects how these waves combine and interfere with each other.
Yes, phase invariance can be observed in everyday life through various phenomena such as interference patterns in water waves or sound waves. It is also utilized in technologies such as radio and television broadcasting.
While phase invariance is a fundamental property of electromagnetic waves, it is not absolute. It can be affected by external factors such as interactions with matter and gravitational fields, which can alter the phase of the wave. Additionally, in certain situations, phase invariance may not hold for certain types of electromagnetic waves, such as those with non-linear properties.