Events at Physics |
The expansion rate and its evolution must be empirically determined for our Universe to reveal its composition, scale, age, and fate. In 1998, high-redshift SNe Ia provided the first and only direct evidence for an accelerating Universe and the existence of dark energy. To identify the nature of dark energy we seek to improve on past and present measurements of the recent history of cosmic expansion. Today's keystones of expansion are distant type Ia supernovae and Cepheid variables in their hosts. I will report on new calibrations of the Hubble diagram of SNe Ia with new SN Ia and Cepheid data and an extension of its reach to <br>
z > 1 when cosmic expansion was still decelerating. These measurements are providing new clues about the nature of the mysterious dark energy.<br>
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