The Hunt for Dark Energy with Jason Rhodes

August 25, 2026

AI Summary

5 min read

When the two teams that discovered dark energy in the 1990s independently realized the universe’s expansion was accelerating rather than slowing down, both thought the result had to be wrong. That moment of productive confusion — and the fact that two independent groups were needed to trust it — captures the central tension NASA’s Nancy Grace Roman Space Telescope is designed to resolve. As Jason Rhodes, a senior research scientist at NASA’s Jet Propulsion Laboratory, explains on this episode of StarTalk, Roman will use three separate techniques to study dark energy simultaneously, precisely because any single method can mislead. And if the results don’t match? That’s not failure — it’s a clue.

What the Roman telescope is and why it’s going to L2

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What you'll learn

1 (02:00) **Jason Rhodes Introduction** - Senior Research Scientist at NASA's JPL returns to discuss the Nancy Grace Roman Space Telescope and its hunt for dark energy.
2 (02:57) **Who Was Nancy Grace Roman?** - NASA's first chief astronomer, champion of space telescopes, and "mother of the Hubble Space Telescope."
3 (04:01) **Why Space? Above the Atmosphere** - The biggest advantage is escaping Earth's atmosphere, which causes stars to "twinkle" and blurs images.
4 (06:14) **Satellite Pollution and the Need for L2** - A rapid increase in low-Earth-orbit satellites (like Starlink) is creating light pollution and streaks in astronomical images.
5 (08:13) **How Roman Tracks Invisible Dark Energy** - The telescope will use three distinct methods to measure dark energy indirectly, since it cannot be seen.
6 (09:48) **The 1990s Revolution: Discovering Acceleration** - In the 1990s, two independent teams using supernovae both found the universe's expansion was speeding up, not slowing down as gravity would dictate.
7 (11:03) **The Hubble Tension** - A "cosmology crisis" where measurements of the early universe don't match the universe we see today.

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Show Notes

How do you build a telescope to study something you can't see? Neil deGrasse Tyson and Paul Mecurio sit down with Jason Rhodes, senior research scientist at JPL, to explore the Nancy Grace Roman Space Telescope and its search for answers on dark energy and dark matter.

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Thanks to our Patrons Bullseye, Steve Klein, Mr. G, Rachel Cecil, James Langfels, Amanda Dalton, Mark Robinson, Heyyo, Joshua Clark, Ava, Oliver Thomas, Daniel Treherne, Adam, David Fulps, Hanspeter, Derelict Doug, Maryrose, Robert Latta 3Rd, Benjamin Dudley, Henry De Sosa, AKlight47, Ray, Sarah Storie, Priest Of Forgotten Gods, Yamil Lopez, Patrick Nisius, Jay, Carey-Donois, pupperoni jo, Antonio Codato, slash128, Deedra Hansen, Benjamin Briggs, E, Anita, Gustavo Almeida Neves, Elissa Yoder, Alex, John Nawrocki, preston frizz, Brian Kaiser, Chad Perkins, Junkyard Monk, Lance Steinberg, Dumisani Yishvahk Tembe, Bruno Vieira, Jes Hughson, John Brocklesby, I'm Dave, Darryl Gillespie, Isa, Myopic Philomath, Mo Al-Sheikhly, Stuart, Duane McCurdy, Regina Anavy, Bob Lux, and Vino Miranda for supporting us this week.

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