Fine-structure variable?
Article Abstract:
It is possible that there is evidence for a varying alpha in the fine-structure constant alpha = 2pi-e squared/hc, which characterizes the strength of the electromagnetic attraction between photons and electrons. This variation is at a level of around one part in 10 to the fifth power, over about half the lifetime of the Universe. This evidence has been obtained from research looking at possible time variation in alpha using cosmological observations of the absorption spectra of distant (high-redshift) quasars. There are number of potential sources of systematic error in this approach.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1999
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A high deuterium abundance in the early universe
Article Abstract:
The ratio of deuterium to hydrogen (D/H) within high redshift quasar absorption line clouds determines the density of baryons in the Universe. It is measured from absorption lines in the spectra of more distant quasars lying along the same line of sight. The recommended range in estimating D/H in such clouds is 4x10(-5)(lesser than)D/H(lesser than)2.4x10(-4). This range is consistent with (7)Li and (4)He measurements.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1997
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The inconstant constant?
Article Abstract:
An attempt is made to use the technique of measuring radiation from distant quasars. It is determined that the value of the fine-structure constant, which reflects the quantization of electron energies within the atom, has changed over the history of the Universe.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 2004
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