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.

 

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