From StarTalk.
How did scientists discover evidence for dark energy? Neil deGrasse Tyson and comedian Paul Mecurio explore dark energy, Hubble tension, and the beginning and end of the universe with astrophysicist and Nobel laureate, Adam Riess.
Learn the story of how Adam helped discover dark energy, and how he wrote equations expecting to measure deceleration only to watch his computer spit out negative mass, signaling acceleration instead. From calibrating candles to worrying about bad weather on Hubble observing nights, he walks through the beautiful mistake that held up.
Learn how astronomers once wondered whether there was enough matter to slow the universe’s expansion, and how parallax, Gaia data, Cepheid variables, and the search for ever-brighter standard candles led them to Type Ia supernovae. He breaks down why these explosions are so uniform, how the Chandrasekhar limit works, and how dust tricks astronomers by dimming and reddening starlight.
The conversation widens to dark energy’s role in the universe’s ultimate fate: the Big Freeze, Big Rip, or Big Crunch. We discuss the ΛCDM model, where 97% of the universe remains unknown. We explore Hubble tension, why early- and late-universe measurements refuse to overlap, and whether shifting dark energy, new particles, magnetic fields in the primordial plasma, or revised pre-CMB physics could reconcile the mismatch. With JWST confirming Hubble’s results, new facilities on the horizon, and the community hunting for overlooked assumptions, sometimes the universe moves the goalposts, and our job is to follow the thread.
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Timestamps:
00:00 – Introduction: Adam Riess
05:10 – The Mysterious Term in Einstein’s Equations
11:08 – Finding Standard Candles
18:47 – Supernovas, Cepheids & Dust
23:32 – Discovering the Universe’s Accelerating Expansion
31:55 – The Emergence of Hubble Tension
37:59 – Is Dark Energy Shifting?
42:29 – Transforming Our Understanding & New Measurements
52:31 – Resolving Hubble Tension
55:42 – Error & Democratization of Science
59:32 – Chunky Space
01:00:52 – The Age Crisis
01:02.25 – A Cosmic Perspective
01:06:00 – Closing
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Science meets pop culture on StarTalk! Astrophysicist & Hayden Planetarium director Neil deGrasse Tyson, his comic co-hosts, guest celebrities & scientists discuss astronomy, physics, and everything else about life in the universe. Keep Looking Up!
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