Measuring the Hubble constant

The Hubble constant: Measuring the age and size of the Universe

A century ago astronomers thought that the Universe was static. Then, in 1929, Edwin Hubble demonstrated that it is actually expanding. For the remainder of the 20th century astronomers tried to measure the expansion rate, arriving at figures that differed by a factor of two. The Hubble Space Telescope (HST) was designed and built to resolve that very controversy. As a result, at the turn of the 21st century the Hubble constant was known to an accuracy of 10%. Now cosmologists and physicists are striving to reduce the remaining uncertainty to just 1%. This talk will say why this is so important and report recent progress, including results at infrared wavelengths from the Spitzer Space Telescope.


About Barry Madore

Barry Madore is a Senior Research Astronomer at the Observatories of the Carnegie Institution of Washington, based in Pasadena, California. He is also the Lead Scientist on the NASA Extragalactic Database (NED) which he co-founded 25 years ago. Dr Madore was a founding member of the Hubble Space Telescope Key Project Team that in 2001 determined the expansion rate of the Universe to 10%, ending a century-long controversy. He is also a co-investigator on the Galaxy Evolution Explorer (GALEX) satellite. His current scientific interests concern observational aspects of star formation, the extragalactic distance scale, peculiar galaxies and variable stars. Most recently he has been exploring the limits to knowledge in cosmology.

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