Tired light

<p>Tired light is a class of hypothetical <a href="/facts/Redshift/Qfl4VjDF">redshift</a> mechanisms that was proposed as an alternative explanation for the <a href="/facts/Hubble%27s_law/FJYfELCP">redshift-distance relationship</a>. These models have been proposed as alternatives to the models that involve the <a href="/facts/Expansion_of_the_universe/f6Uvt79B">expansion of the universe</a>. The concept was first proposed in 1929 by <a href="/facts/Fritz_Zwicky/E4S5dcmD">Fritz Zwicky</a>, who suggested that if photons lost energy over time through collisions with other particles in a regular way, the more distant objects would appear redder than more nearby ones.
</p><p>Zwicky acknowledged that any sort of <a href="/facts/Scattering/nMou7lEH">scattering</a> of light would blur the images of distant objects more than what is seen. Additionally, the <a href="/facts/Tolman_surface_brightness_test/CbmN3l3c">surface brightness of galaxies evolving with time</a>, <a href="/facts/Time_dilation/fYj7FYbK">time dilation</a> of cosmological sources, and a thermal spectrum of the <a href="/facts/Cosmic_microwave_background/ThB2HkLS">cosmic microwave background</a> have been observed—these effects should not be present if the cosmological redshift was due to any tired light scattering mechanism. Despite periodic re-examination of the concept, tired light has not been supported by observational tests and remains a <a href="/facts/Fringe_physics/qL02Mo3w">fringe topic</a> in astrophysics.
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Tired light open-in-new

Tired light