StarTalk Radio: Cosmic Queries – Multiverse Nesting Dolls

Host: Neil deGrasse Tyson
Co-host: Paul Mercurio
Release Date: December 9, 2025

Episode Overview

Main Theme:
This episode of StarTalk’s “Cosmic Queries” is a grab-bag focused overwhelmingly on the mind-bending physics and metaphysics of black holes, multiverse theory, and wormholes. Neil and comedian Paul Mercurio field listener questions about everything from whether we’re living inside a black hole, to what the fate of the universe might be, to the philosophical implications of Nietzsche’s eternal recurrence. The conversation combines cosmic science with humor, making esoteric topics accessible and entertaining.

Key Discussion Points and Insights

1. Are We Living Inside a Black Hole? (06:05 – 10:53)

• Question: Could our universe be inside a black hole, and if black holes can merge in our “parent universe,” would we notice?
• Neil: Black holes are "black" from the outside, but inside, you'd see light funneled from the outside. If our black hole merged with another, "you'd see the other black hole collide with you. The event horizons would merge, and all matter would join."
  • "[When black holes merge] you'll join each other, have a common envelope, and a common event horizon...all headed towards the singularity." (07:05)
• Nested universes: The “nesting dolls” idea is invoked—universes inside black holes inside universes, possibly endlessly.
• The conversation turns humorous about neglectful cosmic “parents” in this nested family tree.

2. What Lies Beyond Black Holes? (09:41 – 12:11)

• Question: What’s beyond a black hole?
• Neil: Down the center is a singularity, but for spinning black holes, the interior could form a new spacetime—a new universe.
  • Introduces the theory of “cosmic natural selection,” where universes that favor black hole creation produce more baby universes.
  • Analogy: "Cosmic tribbles... they're born pregnant." (11:26) – Universes prolific with black holes endlessly spawn new universes.

3. Observing and Confirming Black Hole Theories (15:53 – 21:32)

• Question: How is Hawking’s theory about black holes tested, given their distance?
• Neil: "We have yet to see any edges where quantum mechanics fails us. That's why we're on board with Hawking radiation." (19:29)
  • Explains Hawking radiation can only be inferred by trusting quantum mechanics, not direct observation.
  • Observationally, we infer black holes from the energetic chaos and gravitational effects (e.g., X-ray emissions from accretion disks, orbits of stars, gravitational waves).

4. Gravity Slingshots and Navigating Around Black Holes (21:36 – 27:43)

• Question: Could we use a black hole for a slingshot maneuver like in “The Martian”?

• Neil: Gravity slingshots are real (all missions to outer planets use them), but only work due to planetary motion. "It's not the gravity; it's the relative motion that gives you the energy boost." (23:19)

  • With black holes: Only useful if the black hole is moving in your desired direction—which is not likely!

• Bonus Anecdote: Neil’s story about drafting behind a truck to save gas, paralleling “drafting” in space navigation. (25:09)

  • “I got within about 20ft and it went to 99mpg… so I was completely enclosed…” (26:30)

5. Time Dilation, Spaghettification & Perceptions Near Event Horizons (28:30 – 33:23)

• Question: Does time stop at a black hole's event horizon?
• Neil: Early ideas (Walter Sullivan’s “Frozen Star”): to distant observers, objects falling in appear to freeze at the horizon. Modern understanding: you actually pass through the event horizon without incident ("you're absorbed") but can't escape.
  • "It's as you approach the singularity, deep in the center…where these effects become significant." (31:11)
• Paul mines dark comedy around work meetings and time dilation.

6. Science Education for Neurodiverse Learners (33:29 – 39:52)

• Question: How to learn physics with ADHD if reading is hard?
• Neil: Recommends his book Letters from an Astrophysicist (bite-sized Q&A), the Merlin books, and audiobooks he narrates himself (“with my Barry White voice”). (38:17)
• Broader Point:
  • "School systems value grades more than students value learning. This is why people cheat." (46:48)
• Adds: Khan Academy has helpful lessons, and discusses the distinction between “theory” and “law.”

7. Nietzsche’s Eternal Recurrence & Multiverse Philosophy (40:52 – 44:49)

• Question: Will everything that happens happen again?
• Neil: Discusses “infinite universes in the multiverse creates all possible configurations,” but “another version of you isn’t really you.”
  • "We have twins. Identical in every way. They're not having the same thoughts. They're different people, but they're identical." (44:46)
• Paul laments alternate selves being stuck on hold with customer service “forever.”

8. From Theory to Law & What Does ‘Proof’ Mean? (47:46 – 52:51)

• Question: Is atomic fission natural, and why are Einstein’s ideas still called “theory”?
• Neil: Science no longer upgrades theories to “laws” after learning that “laws” have limits (e.g., Newton’s laws break down at relativistic scales).
  • "It's not we're waiting for the theory to become a law. That's not how this works…Theories explain and organize evidence, but with limits." (48:33)
• “Proof” isn’t a concept in science—just overwhelming evidence.

9. Are Black Holes Fossilized Wormholes? (53:14 – 55:10)

• Question: Are black holes the fossil remains of collapsed wormholes?
• Neil: Wormholes are not stable in theory; they require “negative gravity” matter we don’t have. Black holes aren’t one-way wormholes; they swallow and don’t allow return.
  • "When I think of wormholes, I want to step through and land somewhere else and be able to step back...Black holes don't give you that option." (54:57)

10. Should Humanity Focus on Surviving the Sun’s Demise? (55:49 – 59:55)

• Question: Since the Sun will destroy us in 5 billion years, should our focus be survival?
• Neil: "We will surely go extinct for 22 other reasons before then," listing asteroids, viruses, and climate change. (57:16)
  • Jokes about “future Amazon Prime wormholes”—refrigerators with intergalactic wormhole doors for food delivery.

Notable Quotes & Memorable Moments

• Neil deGrasse Tyson:

  • "Gravity is symmetrical...if it’s just pure gravity, you don’t gain anything." (23:19)
  • "We’re not waiting for the theory to become a law. That’s not how science works anymore." (48:43)
  • "No such thing as 'just a theory'...Einstein had a theory, you have a hypothesis." (51:24)
  • "If you're not a good reader, maybe you're a good listener. Those two Merlin books? Yeah, I narrated them—with my Barry White voice." (38:17)
  • "In another universe, I don’t give a rat." (44:49) (on multiversal “other selves”)

• Paul Mercurio:

  • "Some people speculate there’s a black hole out there, but you see all the chaos around it—it’s like that coworker you never see but have to clean up after." (20:15)
  • "I really wish I'd spent a few cycles in the beginning learning to fold a fitted sheet...never learned it." (42:51)
  • "Is there any downside to a wormhole universe? Everyone who had a job driving..." (60:04)

Humorous Highlights

• Analogies abound: black hole mergers as dysfunctional family Thanksgiving dinners; cosmic objects likened to “pregnant cosmic piñatas” and “cosmic tribbles”; gravity slingshots compared to riding a bike behind a jet engine; time dilation at work meetings (“feel like they’re near a black hole”).
• Repeated comic jabs about Neil’s self-promotion of his own books (“More pictures, buddy. More pictures.”) and Barry White–style audiobook narration (38:14).
• Paul's bit about “learning physics at a keg party” and cheating for grades (34:10, 36:42).
• Extended riff on folding fitted sheets through all possible universes, and Neil coaching Paul on how it’s done (42:51).
• Imagining wormholes as doors in your fridge straight to the grocery store (58:27).

Timestamps for Major Segments

| Segment | Timestamp (MM:SS) | |---------------------------------------------------------------------|----------------------| | Opening, black hole allure | 02:10 | | Are we living in a black hole? | 06:05 | | What’s beyond black holes? | 09:41 | | Can we confirm black hole theories (Hawking’s ideas)? | 15:53 | | Using planetary & black hole slingshots | 21:36 | | Time slows near black holes; spaghettification | 28:30 | | Science education tips for neurodiverse learners | 33:29 | | Multiverse and Nietzsche’s eternal recurrence | 40:52 | | Theory vs. law; what is scientific proof? | 47:46 | | Are black holes collapsed wormholes? | 53:14 | | Should humans devote energy to beating the Sun’s demise? | 55:49 | | Wormholes and speculative future tech (delivery, roads vanish) | 58:27 | | Episode wrap-up and sign-off | 60:21 |

Final Thoughts

This episode balances expansive cosmic speculation with practical physics, all seasoned with Paul’s irreverent humor and Neil’s skill for clear, engaging explanations. Black holes serve as the dominant theme, but the show loops through slingshot physics, alternate universes, time perception, and the future of science learning—reminding listeners that the true “nesting doll” is the endless curiosity with which we explore the mysteries of the cosmos.

As Neil closes:
"Until next time—keep looking up." (61:17)