Professor Richard Fitzpatrick: "Thus, the moving observer sees a wave possessing the same wavelength...but a different frequency...to that seen by the stationary observer." http://farside.ph.utexas.edu/teaching/315/Waveshtml/node41.html

Constant wavelength of light entails variable speed of light relative to the observer - this is fatal for Einstein's relativity and modern physics as a whole. In order to save modern physics, Fitzpatrick should change his text, e.g. in the following way:

Except for the Doppler-in-light scenario, the moving observer sees a wave possessing the same wavelength but a different frequency to that seen by the stationary observer. In the Doppler-in-light scenario, however, the moving observer sees the wavelength changed: from λ, as seen by the stationary observer, to λ'=λc/(c±v), where v is the speed of the observer relative to the light source.

Richard Fitzpatrick doesn't, but Kip Thorne does know why the moving observer should see the wavelength of light changed:

Kip Thorne: "If you move toward the [light] source, you see the wavelength shortened but you don't see the speed changed." https://youtu.be/mvdlN4H4T54?t=296

See more here: https://twitter.com/pentcho_valev

Pentcho Valev

Professor Martin White, UC Berkeley, has found an original way to brainwash his students. Since the motion of the observer SHOULD change the wavelength of the incoming light (otherwise Einstein's relativity and modern physics collapse), heretic doubts will be avoided if students are convinced that the motion of the observer changes the wavelength of any waves, e.g. sound waves:

Professor Martin White, UC Berkeley: "...the sound waves have a fixed wavelength (distance between two crests or two troughs) only if you're not moving relative to the source of the sound. If you are moving away from the source (or equivalently it is receding from you) then each crest will take a little longer to reach you, and so you'll perceive a longer wavelength. Similarly if you're approaching the source, then you'll be meeting each crest a little earlier, and so you'll perceive a shorter wavelength...The same principle applies for light as well as for sound. In detail the amount of shift depends a little differently on the speed, since we have to do the calculation in the context of special relativity. But in general it's just the same: if you're approaching a light source you see shorter wavelengths (a blue-shift), while if you're moving away you see longer wavelengths (a red-shift)." http://w.astro.berkeley.edu/~mwhite/darkmatter/dopplershift.html

Here is an illustration of how the motion of the observer breathtakingly changes the wavelength of sound waves:

https://bretagnemontagne.files.wordpress.com/2011/02/23.jpg

More here: https://twitter.com/pentcho_valev

Pentcho Valev

On Tuesday, March 28, 2023 at 3:32:12 AM UTC-5, Pentcho Valev wrote:
> Professor Martin White, UC Berkeley, has found an original way to brainwash his students. Since the motion of the observer SHOULD change the wavelength of the incoming light (otherwise Einstein's relativity and modern physics collapse), heretic doubts will be avoided if students are convinced that the motion of the observer changes the wavelength of any waves, e.g. sound waves:
>
> Professor Martin White, UC Berkeley: "...the sound waves have a fixed wavelength (distance between two crests or two troughs) only if you're not moving relative to the source of the sound. If you are moving away from the source (or equivalently it is receding from you) then each crest will take a little longer to reach you, and so you'll perceive a longer wavelength. Similarly if you're approaching the source, then you'll be meeting each crest a little earlier, and so you'll perceive a shorter wavelength...The same principle applies for light as well as for sound. In detail the amount of shift depends a little differently on the speed, since we have to do the calculation in the context of special relativity. But in general it's just the same: if you're approaching a light source you see shorter wavelengths (a blue-shift), while if you're moving away you see longer wavelengths (a red-shift)." http://w.astro.berkeley.edu/~mwhite/darkmatter/dopplershift.html
>
> Here is an illustration of how the motion of the observer breathtakingly changes the wavelength of sound waves:
>
> https://bretagnemontagne.files.wordpress.com/2011/02/23.jpg
>
> More here: https://twitter.com/pentcho_valev
>
> Pentcho Valev

https://drive.google.com/file/d/1VfhOL63jvB2Dmn4JCRmOx6S8Dh9nRbdC/view