Welcome to the Cosmology page and some basic information


Introduction: Cosmology

Cosmologists study the universe a whole: its birth, growth, shape, size and eventual fate. The vast scale of the universe became clear in the 1920s when Edwin Hubble proved that "spiral nebulae" are actually other galaxies like ours, millions to billions of light years away.

Hubble found that most galaxies are red shifted: the spectrum of their light is moved to longer, redder wavelengths. This can be explained as a Doppler shift if the galaxies are moving away from us. Fainter, more distant galaxies have higher red shift, implying that they are receding faster, in a relationship set by the Hubble constant.

The discovery that the whole universe is expanding led to the big bang theory. This states that if everything is flying apart now, it was once presumably packed much closer together, in a hot dense state. A rival idea, the steady state theory, holds that new matter is constantly being created to fill the gaps generated by expansion.



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Galileo in Orbit