Cool Worlds Podcast #24 Colin Hill - Modern Cosmology, Hubble Tension, Exotic Physics
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Aug 8, 2025 Colin Hill, a Professor of Physics at Columbia University, is a prominent voice in modern cosmology. He discusses the intriguing Hubble tension and its implications for our understanding of the universe's expansion. The conversation dives into cosmic microwave background (CMB) radiation, revealing its role in uncovering the universe's early moments. Colin also shares insights on exotic particles like axions, gravitational lensing, and the future of cosmological research, highlighting fascinating connections between physics and music to illustrate complex concepts.
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CMB Is Remnant Heat From The Big Bang
- The CMB is the cooled remnant radiation from the hot Big Bang.
- Colin Hill explains it comes from an early ionized plasma that cooled as the universe expanded.
Pigeons Helped Reveal The CMB
- Arno Penzias and Robert Wilson detected a persistent hiss on their Bell Labs antenna.
- They killed pigeons in the telescope before learning the hiss was the cosmic microwave background.
Last Scattering Freed The CMB Photons
- At ~380,000 years hydrogen recombined and photons stopped scattering, letting light free-stream.
- Colin Hill calls that moment recombination or 'last scattering' and it's the earliest light we can see.