Recent Observations
Recent observations of quasar absorption systems have once
again generated interest in the idea that the fine structure constant may
vary in time. These observations were done by spectroscopic analysis of the
light from distant quasars through gas clouds. When a cloud of gas is between
a light source (a quasar) and a prism, dark lines are superimposed upon the
normal rainbow spectrum. These dark lines are called absorption lines and
they are related to the energy levels of the atoms in the gas. Spectrocopy
allows us to observe the splitting of certain energy levels in those atoms
which allow us to determine the fine structure constant. If the fine structure
constant did change over time, the absorption spectra from these quasars would
have changed as well. In 2001, John Webb of the University of New South Wales
reported that by his analysis, the fine structure constant 12 billion years
ago was different than it's value today. However, in 2004, a team of astromomers
led by Patrick Petitjean and Raghunathan Srianand have produced a study that
shows for the last 10,000 million years the relative variation in the fine
structure constant is less than 0.6 part per million. The best result from
quasar absorption lines studies to date.
Taken from Here
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