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36 votes
Accepted

Light waves can't have a wavelength

You're right in saying that you can't always attribute a unique wavelength to an electromagnetic field. However, it's a simple consequence of Fourier analysis that you can write any field as a ...
Sahand Tabatabaei's user avatar
4 votes

Light waves can't have a wavelength

Something does not need to be sinusoidal in order to have a wavelength. It just needs to be periodic or repeat after a certain distance. More generally, if $\lambda$ is the smallest non-negative real ...
Jbag1212's user avatar
  • 2,569
2 votes

Light waves can't have a wavelength

Sahand gave a really great answer but I'd like to offer a different perspective. Edit: It was pointed out in the comments that energy conservation isn't enough to give periodic solutions. Which is ...
ShawnS's user avatar
  • 51
2 votes

Minimum frequency for a dipole antenna to work

As already remarked in the comments, the optimal frequency is based on the "1/2 wavelength" rule. But to what extent do things get worse at lower frequencies? To make this more ...
Jos Bergervoet's user avatar
2 votes

Minimum frequency for a dipole antenna to work

No, but to maximize the radiated power at any frequency the dipole (horizontal, center-fed) must be 1/2 wavelength long. This means 5 meters at 30 megahertz, 50 meters at 3 megahertz, 500 meters at ...
niels nielsen's user avatar
1 vote

Could the increasing anisotropy of the universe lead to an additional blueshift?

It seems to me that what you are pointing out is related to what is known as the (integrated) Sachs-Wolfe effect, which has been considered in the missions that have measured the CMB anisotropies (...
ouroboros's user avatar
1 vote

Does the energy of a photon in comoving space change?

The energy of the photon decreases as the reciprocal of the scale factor. Typically, this can be interpreted as the wavelength being "stretched" by the expansion, but alternatively you can ...
ProfRob's user avatar
  • 132k

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