Matt O'Dowd

Things Matt Says on Podcasts

Is an astrophysicist and associate professor at Lehman College, City University of New York, with a research background in astronomy and astrophysics from the University of Melbourne and the Space Telescope Science Institute. He is also a staff scientist at the American Museum of Natural History. Since 2015 he has written and hosted PBS Space Time, a PBS Digital Studios series that has become the largest physics and space show on YouTube, with over 3 million subscribers. On the show he lays out competing cosmology theories, from cyclic and bouncing universes to black-hole-born ones, on what may have preceded the Big Bang.

Where to Find Them

Matt O'Dowd hosts PBS Space Time and writes StarTalk Radio . They have also been a guest on Radiolab .

Recently: “The Future of Space Telescopes” on PBS Space Time (October 2026); “Are the Fundamental Constants Changing?” on PBS Space Time (October 2026); “When Quasars Collide STJC” on PBS Space Time (October 2026); “The Nature of Nothing | Space Time” on PBS Space Time (October 2026); “The Missing Mass Mystery” on PBS Space Time (October 2026); “The Vacuum Catastrophe” on PBS Space Time (October 2026).

What They Said

“People love cyclic and regenerating universes. They appeal to our sense of narrative, which might be a reason to be wary of these hypotheses.” — Matt O'Dowd, PBS Space Time

O'Dowd had just run through the alternatives to a singularity at the start of time: cosmic inflation, the Big Bounce, colliding branes in the Steinhardt-Turok model, Penrose's conformal cyclic cosmology, Smolin's universes born inside black holes. Having laid out how satisfying the cyclic options are, he turns that satisfaction into a reason for suspicion.

PBS Space Time · 2026-08-23 Permalink → Listen →
PBS Space Time Around 08:30 into the episode
Speaker 1

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Matt O'Dowd

…could initiate a new Big Bang given infinite time. Or the same amount of time could lead to all particles randomly converging back to the same spot. Or maybe black holes birth new universes as in Lee Smallins' fecund universe hypothesis. There's a poetry to that last one. The geodesics approaching the black hole singularity become the geodesics emerging from the new Big Bang singularity. People love cyclic and regenerating universes. They appeal to our sense of narrative, which might be a reason to be wary of these hypotheses. Now, they also appeal to our intuition for causality.

Speaker 1

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Matt O'Dowd

Things happen because prior events cause them. Many of our ideas just push back the uncomfortable something from nothing moments. Physicists have a thing or two to say about that, from quantum fluctuations from nothing to Stephen Hawking's timeless interpretation of internal inflation that draws on…

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