StarTalk Radio Episode Summary: "Hubble Trouble with Hakeem Oluseyi"

Release Date: March 4, 2025

Hosts:

• Neil deGrasse Tyson – Astrophysicist and Director of the Hayden Planetarium.
• Paul Mercurio – Comedian and co-host.
• Guest: Hakeem Oluseyi – Astrophysicist, Cosmologist, and CEO of the Astronomical Society of the Pacific.

1. Introduction and Guest Welcome (02:08 - 04:22)

Neil deGrasse Tyson kicks off the episode by welcoming his co-host, Paul Mercurio, and introducing the esteemed guest, Dr. Hakeem Oluseyi. The discussion begins with light-hearted banter about Hakeem's comedic endeavors and his recent one-man show, "Permission to Speak," directed by Frank Oz.

Notable Quotes:

• Paul Mercurio (02:12): "He knows his stuff, man. He's in charge of a lot of acronyms."
• Neil deGrasse Tyson (04:16): "So you got a podcast. Does It Fly? By Roddenberry Entertainment."

2. Astronomical Society of the Pacific and Hakeem's Role (05:03 - 09:00)

Hakeem delves into his role as CEO of the Astronomical Society of the Pacific (ASP), highlighting its mission to promote public awareness and understanding of astronomy. He emphasizes the organization's inclusive approach, welcoming both professional and amateur astronomers, educators, and enthusiasts alike.

Notable Quotes:

• Hakeem Oluseyi (05:38): "When I went to the Bay Area in '91 for graduate school, I discovered the ASP. It was an egalitarian perspective from the start."
• Paul Mercurio (08:07): "Why the term Pacific?"

3. Hubble Tension: Measurement Discrepancies (17:13 - 22:07)

The conversation shifts to the "Hubble tension," a pressing issue in cosmology where measurements of the universe's expansion rate (Hubble constant) from the early universe (cosmic microwave background) and the local universe (supernovae) do not align. Hakeem discusses potential reasons for this discrepancy, contemplating whether it's a flaw in current models, measurement errors, or indicative of new physics.

Notable Quotes:

• James H. English (17:35): "The universe is expanding too fast for our theories and models to fit."
• Hakeem Oluseyi (19:24): "People have been throwing out the Big Bang or dark energy as explanations, but it's more likely there's something we haven't discovered yet."
• Neil deGrasse Tyson (20:55): "Measurements look good. I was involved in supernova cosmology…"

4. Detection of Atmospheric Particles on Exoplanets (27:04 - 30:06)

Responding to a listener's question, Hakeem explains the technique of using transit spectroscopy to detect various particles in the atmospheres of distant exoplanets. By analyzing the light that passes through a planet's atmosphere during a transit, scientists can identify specific elements and molecules based on absorption patterns.

Notable Quotes:

• Adam Omelon (28:35): "How exactly does the light alteration happen when it travels towards us?"
• Hakeem Oluseyi (28:55): "As a planet transits its star, the light interacts with its atmosphere, absorbing specific wavelengths that reveal its composition."
• Neil deGrasse Tyson (30:03): "James Webb Space Telescope has succeeded in doing that job. It's opened up the whole industry."

5. Dark Matter: Theories and Challenges (30:10 - 35:18)

Hakeem and Neil engage in a deep dive into the enigmatic nature of dark matter. They discuss various hypotheses, including MACHOs (Massive Compact Halo Objects) and WIMPs (Weakly Interacting Massive Particles), and the ongoing challenges in detecting dark matter directly. Hakeem reflects on his early research experiences and the iterative nature of scientific discovery.

Notable Quotes:

• Jordan Vesina (30:16): "Is it possible that dark matter defies our understanding of the laws of physics?"
• Hakeem Oluseyi (31:28): "We have models – hot dark matter, cold dark matter – and neither fully accounts for what we observe."
• Neil deGrasse Tyson (33:11): "MACHOs would be massive compact halo objects."

6. Gravitational Waves and Their Effects on Time (36:15 - 40:58)

A listener named David raises a question about gravitational waves and their potential to alter time. Hakeem explains the subtle nature of gravitational waves and their interaction with spacetime, emphasizing that while they can warp spacetime, the effects are incredibly minute and not noticeable to humans without sensitive instruments.

Notable Quotes:

• David (36:25): "Can gravitational waves also alter time? If a huge collision occurred near our solar system, how would we feel them?"
• Hakeem Oluseyi (37:05): "Gravitational waves curve space and stretch time, similar to what black holes do."
• Neil deGrasse Tyson (40:11): "The first gravitational wave measured jiggled the experiment by one-twentieth the diameter of a proton. You ain't feeling that."

7. Listener Questions: Conservation of Information in Black Holes, Dark Energy and the Big Squeeze, Dyson Spheres (41:02 - 48:44)

In the Lightning Round segment, listeners pose intriguing questions:

• Conservation of Information in Black Holes: Paul questions the philosophical underpinnings of information conservation in black holes. Hakeem discusses ongoing debates and theories, referencing the "no-hair theorem" and the challenges in reconciling quantum mechanics with general relativity.

• Dark Energy and the Big Squeeze: Ross from Madison inquires whether dark energy could be the mechanism behind a potential "Big Squeeze" (Big Crunch). The panel clarifies misconceptions about dark energy's role in the universe's expansion, emphasizing that current understanding suggests perpetual expansion rather than a climatic contraction.

• Dyson Spheres Detection Criteria: Christopher from St. Louis asks about the criteria used to differentiate Dyson spheres from natural stellar phenomena. Hakeem debunks the concept by highlighting the impracticality of constructing such megastructures with available materials and underscores that observations of red stars can often be explained by interstellar dust.

Notable Quotes:

• Paul Mercurio (41:02): "Physicists' preoccupation with conservation of information sounds more philosophical than scientific."
• Ross (44:00): "Could dark energy be the mechanism behind the big squeeze?"
• Christopher (45:03): "What criteria are we using to distinguish a Dyson sphere from something else?"

8. Conclusion and Final Remarks (48:44 - End)

As the episode wraps up, Hakeem and Paul share final thoughts, encouraging listeners to engage with the Astronomical Society of the Pacific and continue exploring the cosmos. Neil deGrasse Tyson closes with his signature farewell, urging everyone to "keep looking up."

Notable Quotes:

• Hakeem Oluseyi (48:37): "You could be a nerd, a geek, an enthusiast, or an educator. Join our community at Astrosociety.org."
• Neil deGrasse Tyson (51:17): "Till next time, I bid you keep looking up."

Insights and Takeaways:

• Hubble Tension Significance: The ongoing discrepancy in the Hubble constant measurements underscores potential gaps in our cosmological models or hints at new physics yet to be discovered.

• Technological Advancements: Instruments like the James Webb Space Telescope are revolutionizing our ability to study exoplanet atmospheres and search for phenomena like Dyson spheres, though natural explanations often prevail.

• Dark Matter Mysteries: Despite extensive research, dark matter remains elusive, prompting scientists to explore a myriad of theories, each with its own set of challenges.

• Public Engagement: The Astronomical Society of the Pacific plays a pivotal role in democratizing astronomy, fostering an inclusive environment for enthusiasts and professionals alike.

Final Thought: This episode of StarTalk Radio, featuring Dr. Hakeem Oluseyi, offers a profound exploration of some of the most pressing questions in modern astronomy and cosmology. Through expert insights and engaging dialogue, listeners gain a deeper understanding of the universe's complexities and the scientific endeavors striving to unravel them.