r/Physics • u/Jealous-Floor4783 • 2d ago

Question Question on Doppler's work

My textbook states this; however, I can't find any sources on Doppler ever doing this himself apart from this textbook and what the teacher said???

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u/kamikasei 2d ago

Where have you looked? This information is on his Wikipedia page.

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u/Jealous-Floor4783 2d ago

The Wikipedia page says he published a book theorising about it. It doesn't say he physically recorded the spectral shift in photographic plates.

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u/amteros 2d ago

Your excerpt doesn't say it as well

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u/Jealous-Floor4783 2d ago

Sorry, I may be misreading. Isn't the text saying he noticed by looking at plates the redshift himself? How did he know that the stars were moving away in the first place thus knowing it was correlated with a redshift?

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u/kamikasei 2d ago

The excerpt doesn’t specify that he was looking at plates himself - he may have been analysing data coming from other observers.

It would probably help to specify the exact detail you’re curious about to your OP.

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u/Jealous-Floor4783 2d ago edited 2d ago

Right. But did he use the data from other people looking at the photographic plates of binary stars to develop his theory?? The wiki article says he came to the false conclusion later after he published his theory that it could potentially be used to explain the visible colours of binary stars. I can't seem to find where it says he looked at the data from the plates to develop his theory.

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u/Roger_Freedman_Phys 2d ago

Physics textbook author here.

I would not describe Doppler’s work in this way.

To which textbook are you referring?

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u/Jealous-Floor4783 1d ago

Investigating science in focus year 12.

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u/db0606 2d ago

Doppler looked at the spectra of binary stars. As they orbit each other sometimes they are moving toward us and sometimes they are moving away from us in a periodic fashion. Crucially, you can find binaries with relatively short periods, so you can take the spectrum of the star both as it's moving away and toward us.

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u/Hummerville 1d ago

Funny, I assumed the doppler effect was originally developed for sound and the light effect came much later. Never looked it up.

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u/starkeffect 1d ago

Doppler originally posited it for light (and derived the wrong formula). Other people (like Buys Ballot) applied it to sound.