Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas 118 | Adam Riess on the Expansion of the Universe and a Crisis in Cosmology
Oct 12, 2020
Adam Riess, a Nobel Prize-winning astrophysicist, discusses the universe's accelerating expansion and the intriguing 'Hubble tension'—a discrepancy in the measured expansion rate. He shares insights into the debate between indirect cosmic microwave background measurements and direct observational data. The conversation delves into challenges with current cosmological models, the role of dark energy, and how supernovae act as cosmic distance markers. Riess also emphasizes the importance of collaboration in addressing fundamental questions in cosmology.
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Evidence for Expansion
- The expansion of the universe is supported by the redshift of light from distant objects.
- Time dilation of distant events further confirms this expansion, unlike tired light theories.
Challenges of Distance Measurement
- Measuring distances in space is challenging because the intrinsic properties of celestial objects are unknown.
- Unlike familiar objects like cars, we can't determine the size and luminosity of galaxies or stars directly.
Negative Mass
- Adam Riess's computer program initially suggested a negative mass for the universe, which is physically impossible.
- This led him to Sean Carroll's 1992 review article about the cosmological constant and the possibility of accelerating expansion.