Starts With A Bang #125 - Large-scale structure

Starts With A Bang #125 - Large-scale structure

From Starts With A Bang podcast by Ethan Siegel

January 11, 2026 · 1h 33m

About this episode

The episode discusses emerging challenges to the standard cosmological model, particularly regarding dark energy and the expansion rate of the Universe, featuring expert Dr. Kate Storey-Fisher.

One of the most exciting developments in modern astrophysics isn't merely our standard "concordance cosmology" model, but rather the cracks that seem to be emerging in it. Sure, we've said for some 25 years now that our Universe is 13.8 billion years old, is made of mostly dark energy with a substantial amount of dark matter, and only 5% of all the normal stuff combined: stars, planets, black holes, plasmas, photons, and neutrinos. But more recently, a couple of cosmic conundrums have emerged, leading us to question whether this model is the best picture of reality that we can come up with. We don't merely have the Hubble tension to reckon with, or the fact that different methods yield different values for the expansion rate of the Universe today, but a puzzle over whether dark energy is truly a constant in our Universe, as most physicists have assumed since its discovery back in 1998. While "early relic" methods using CMB or baryon acoustic oscillation data favor a lower value of around 67 km/s/Mpc, "distance ladder" methods instead prefer a higher, incompatible value of around 73 km/s/Mpc. Now, on top of that, new large-scale structure data seems…

People in this episode

Host: Ethan Siegel

Guest: Dr. Kate Storey-Fisher

Topics covered

  • cosmology
  • dark energy
  • Hubble tension
  • large-scale structure
  • astrophysics
  • expansion rate of the Universe

Keywords

  • cosmology
  • dark energy
  • Hubble tension
  • expansion rate
  • large-scale structure
  • astrophysics
  • DESI

Mentioned in this episode

Organizations: DESI, CMB, baryon acoustic oscillation

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