Dark Universe Decoded with Katherine Freese

About This Episode

What are the main candidates for dark matter? Neil deGrasse Tyson and comic co-host Chuck Nice sit down with theoretical physicist Katherine Freese to tackle fan questions about dark matter, dark energy, and the dark universe at large.

The episode opens with Katherine’s work on the search for dark matter, exploring why scientists believe it’s a particle and how enormous liquid xenon detectors are our main tool for detection. Katherine tells us about her paleodetector concept, where scientists will dig up ancient olivine crystals that may have spent a billion years passively collecting dark matter tracks. Could we find evidence of dark matter in the rocks here on Earth?

We explore the DESI experiment and whether the acceleration of the universe’s expansion is slowing down. Does the cosmological constant change over time? We discuss JWST’s images of early galaxies and what they could mean. Could varying dark energy require exotic new physics? Katie walks through how extra spatial dimensions from string theory could explain a shifting cosmological constant. Could our universe be a three-dimensional brane with the tension from surrounding dimensions tugging on our expansion rate?

What are the main candidates for dark matter? Katie lays out the full roster of dark matter candidates: WIMPs, axions, and primordial black holes. Could dark energy be matter flowing in from a parent universe? How do scientists tell the difference between doppler redshift versus “tired light” scenarios where photons simply lose energy over distance. Why doesn’t dark matter clump into planets? Could there be dark galaxies formed from dark matter? Are we close to figuring out dark matter and dark energy?

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