Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas

170 | Priya Natarajan on Galaxies, Black Holes, and Cosmic Anomalies

Oct 25, 2021
Priya Natarajan, a Yale cosmologist and author of Mapping the Heavens, delves into the mysteries of the universe. She discusses gravitational lensing and its role in unlocking secrets about dark matter. Natarajan explores how black holes influence galaxy dynamics and star formation, highlighting their unexpected significance. She also addresses the evolving theories of cold dark matter and the recent cosmic anomalies challenging our understanding, emphasizing the collaborative spirit that drives modern cosmology forward.
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INSIGHT

Light Bending and Modified Gravity

  • Modified gravity theories, while interesting, struggle to explain observed light bending, a key prediction of general relativity.
  • Light bending provides rich information about the distribution of matter in the universe.
INSIGHT

Gravitational Lensing and Dark Matter

  • Gravitational lensing, the bending of light by gravity, helps map the distribution of matter in the universe, including dark matter.
  • By comparing the shapes of galaxies behind and outside of gravitational lenses, cosmologists infer the amount of intervening dark matter.
ANECDOTE

Multiple Images from Lensing

  • In regions with high dark matter concentrations, like galaxy clusters, light can be bent so dramatically that it creates multiple images of a single source.
  • These multiple images have identical spectra, confirming they originate from the same object.
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