• FooBarrington@lemmy.world
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    6 months ago

    When space expands, everything inside is stretched, including light. When light is stretched, its wavelength decreases (= redshift). So you just measure how much lower the light frequency is than you’d expect :)

    • Beartotem
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      6 months ago

      the wavelength increase. The frequency decrease. Red as a wavelength of 700nm while blue is about 500nm.