StarTalk Radio: Cosmic Queries – Total Darkness

Host: Neil deGrasse Tyson
Co-Host: Chuck Nice
Date: April 21, 2026
Theme: Science, pop culture, and comedy collide as listeners' questions on darkness, thermodynamics, photons, telescopes, and the big mysteries of the universe are explored in a classic "Cosmic Queries Grab Bag."

Episode Overview

In this lively Cosmic Queries episode, Neil deGrasse Tyson and comic co-host Chuck Nice tackle a grab bag of listener questions spanning topics from the impossibility of reaching absolute zero and the omnipresence of photons, to the hunt for dark matter and Neil's first telescope. With humor, clarity, and the characteristic StarTalk blend of science and pop culture, the hosts explore the frontiers of knowledge, the overlap of classical and quantum physics, and the tools that enable us to “keep looking up.”

Key Discussion Points & Insights

1. Absolute Zero, Quantum Paradoxes, and Thermodynamics

(Timestamps: 03:23 - 09:21)

• Listener Dalton asks if one could extract infinite energy by getting closer and closer to absolute zero, and if that would violate the laws of thermodynamics.
• Neil explains:
  • There is no “cold” as a substance; cold is simply the absence of heat. (“There's no such thing as cold, right? You can't, like, put cold in something.” – Neil, 04:30)
  • Removing heat reduces temperature, but quantum effects prevent reaching absolute zero.
  • At very low temperatures, quantum fluctuations – “zero-point energy” – persist; you can’t extract energy past this point because there’s no lower state to drop to.
  • “Taking heat out means that particles are moving slower and slower… there's a regime where the quantum fluctuations prevent it from ever stopping its motion.” (Neil, 07:16)
• Popular misconception: Turning the search for “zero-point energy” into sci-fi rocket fuel “doesn’t seem likely… based on what we know.” (Neil, 09:09)
• Notable quote:
  • “Everything that happens in the universe is an electron looking for a place for us. Looking to hang its hat. Yeah. And so, honey, I'm home. A hard day in the circuit.” (Neil, referencing previous guest Betul, 08:38-08:52)

2. Are Photons Everywhere? Seeing in Total Darkness

(Timestamps: 10:04 - 14:45)

• Listener Rachel: Photons must be everywhere if we can see—even in a dark room. Are Big Bang photons (cosmic microwave background) still here?
• Neil answers:
  • Your eyes can only detect visible light, but all objects with any temperature emit photons across the electromagnetic spectrum.
  • “Anything that is at any temperature at all is radiating photons.” (Neil, 12:04)
  • Humans primarily emit infrared photons; cold objects shift to emitting microwaves/radio waves.
  • Cosmic Microwave Background: Photons from the Big Bang, now cooled to microwave energies, fill the universe.
  • Experiencing total darkness: Only truly achievable deep in a cave, after a few turns—no ambient photons from above ground. “Not many people have been in complete total darkness in their life. True.” (Neil, 13:35)
• Memorable moment: Muhammad Ali quote about turning off the lights and being in bed before the room gets dark. (Neil/Chuck, 10:10-10:25)
• Humor: Chuck joking about who actually goes cave spelunking: “That's some white people stuff.” (Chuck, 14:12)

3. Newton’s Law of Cooling

(Timestamps: 16:57 - 20:06)

• Listener Max: “As a side quest, Newton came up with a law of cooling. What are your thoughts?”
• Neil confesses:
  • Surprised Newton originated it, but explains the law: The greater the temperature difference between two materials, the faster the temperature shifts until equilibrium.
  • “The bigger the temperature difference, the faster the rate of change of temperature will be.” (Neil, 19:08)
  • Everyday relevance: Glass of ice water eventually matches room temperature—a “cooling curve.”

4. Unlimited Energy—What Would You Do?

(Timestamps: 20:35 - 23:40)

• Listener “God”/Ben Gruns: If gifted limitless energy, what would you do?
• Neil’s practical answers:
  • Tapping the sun (or beaming solar energy from space, as planned by China).
  • Replicating Iceland’s system: Heat water with geothermal energy, melt city snow—no plows or salt needed.
• Chuck: End energy-related wars—“Most of these wars that we fight are over some form of energy.”
• Neil: With unlimited energy, we could produce food and water abundantly, addressing global needs.

5. Do Galaxies Orbit a Superstructure? The Shape of the Universe

(Timestamps: 24:37 - 27:59)

• Listener Scott: Is the universe pancake-shaped, do galaxies orbit a central structure?
• Neil:
  • Misconception: The universe isn’t a “pancake”—galaxy motions are mostly random, except within clusters.
  • Large-scale galaxy clusters may not even have completed an orbit yet (“not virialized”).
  • “Virialization is the sharing of [orbital/thermal] energy among systems.” (Neil, 27:15)

6. Gravity: Curvature, Force, or Gravitons?

(Timestamps: 28:09 - 30:41)

• Listener Seamus: Is gravity just a side-effect of curved space? Does it need a carrier particle?
• Neil’s nuanced answer:
  • Quantum expectation: Each force has a carrier particle (as with photons for EM force).
  • Hypothetical graviton is proposed, but gravity, as Einstein describes it, may not be a force needing a particle—it could be simply the curvature of spacetime.
  • “Maybe it sits outside the quantum paradigms that would require that there be a graviton.” (Neil, 30:20)
• Memorable story: Neil’s relativity class with the legendary John Archibald Wheeler, where he met his wife. (29:41 - 29:57)

7. Building the Ultimate Telescope with Infinite Budget

(Timestamps: 32:36 - 34:46)

• Listener John Meyer: What would you build with an unlimited telescope budget?
• Neil’s dream:
  • An array of telescopes of all types and bandwidths on the far side of the moon: no atmosphere, no Earth radio noise.
  • Go beyond electromagnetic spectrum: Next-gen telescopes for gravitational waves and neutrinos.
  • “I want...the next generation of telescope that can see gravitational waves and neutrinos. That is not electromagnetic.” (Neil, 34:37-34:44)

8. Is Time Permanent?

(Timestamps: 35:00 - 37:44)

• Listener Tuomas: “Is time permanent?”
• Neil:
  • Quotes Wheeler: “Matter tells space how to curve. Space tells matter how to move. And that motion is defined to make time look simple.” (Neil, 35:48-36:09)
  • Deep musings: Without change or motion, the concept of time dissolves. “Where there is no time reckoning, then nothing moves.”
  • Discusses how eternity in afterlife is conceived as “outside of time”—but for physical objects, it's unclear what that would mean.

9. How Much Does the Universe Weigh?

(Timestamps: 38:03 - 42:19)

• Listener Gavin: “How much does the universe weigh?”
• Neil:
  • Crunches the math—starting from the sun’s mass, stars per galaxy, and galaxies in the observable universe—ends up with a ridiculously big number (“ton”).
  • Don’t forget dark matter: Multiply by six for all the unseen mass.
  • Humor: The “vulgar metric system” of cosmic weight: ass-load < shit-load < ton. (40:03 - 40:18)

10. Dark Matter and Gamma Ray Glow

(Timestamps: 42:34 - 44:11)

• Listener Mile: New findings of gamma ray glow from center of Milky Way, possibly from dark matter (WIMPs). How are these particles different from ordinary matter?
• Neil:
  • “No.” (On whether we can truly explain how WIMPs are different from regular matter, 43:14.)
  • Directs to expert Katie Freese's work.
  • Sceptical: If dark matter annihilation produced gamma rays, we’d expect to see this everywhere, not just at the Milky Way center.

11. Neil’s First Telescope & Stargazing Origins

(Timestamps: 45:28 - 57:01)

• Listener Larry: What was Neil’s first telescope, and does he still have one?
• Neil recounts:
  • First “night sky” was Hayden Planetarium’s dome due to light pollution in the Bronx.
  • First used binoculars, then received a 2.4-inch refractor for his 12th birthday; saw Saturn's rings, Jupiter’s bands, nebulae.
  • Later bought a 6-inch reflector, took it to Africa for a solar eclipse (age 14, claimed he was 15).
  • That 6-inch telescope is now in a Kentucky science museum.
  • Currently owns two digital telescopes, sometimes prefers “old school” observing.
  • Adorably recounts how as a child he’d carve out a path in snowy yards for observing.
  • Memorable story: Police once called by neighbors seeing a “kid with a bazooka” on the roof—it was Neil with his telescope. (55:15-55:40)
  • Children’s book about this incident was “banned in Pennsylvania for showing a police officer in a bad light” (56:23).

Notable Quotes & Memorable Moments

• On reaching absolute zero:
  “You reach a point where quantum phenomena dominates, and you can no longer use classical reasoning.” — Neil (06:59)

• On photons everywhere:
  “Anything that is at any temperature at all is radiating photons.” — Neil (12:04)

• On the mass of the universe:
  “Who cares at that point? The number is too big.” — Chuck (39:39)
  “That is the biggest unit of measure there is: ton.” — Neil (39:50)

• On gravity and quantum theory:
  “Maybe it sits outside the quantum paradigms that would require that there be a graviton.” — Neil (30:20)

• On the beginnings of cosmic curiosity:
  “The binoculars were the gateway drug.” — Neil (48:20)

• On childhood stargazing in the Bronx:
  “There's no night sky to New Yorkers. We had no relationship.” — Neil (46:13)

Timestamps for Important Segments

| Time | Segment/Question | |-----------|-------------------------------------------------------------| | 03:23 | Absolute zero, quantum limits, and thermodynamics | | 10:04 | Photons everywhere, seeing in darkness, CMBR | | 16:57 | Newton’s law of cooling explained | | 20:35 | Unlimited energy—what would you do? | | 24:37 | Galaxy motions, cluster shapes, and virialization | | 28:09 | Gravity—force or side-effect of curved spacetime? | | 32:36 | The ultimate telescope with infinite budget | | 35:00 | Is time permanent? | | 38:03 | Calculating the mass of the universe | | 42:34 | Dark matter, gamma rays, and WIMPs | | 45:28 | Neil’s first telescope and stargazing origins |

Tone & Style

The episode is fast-paced, interactive, and peppered with humor, pop culture references, and friendly banter (“That's some white people stuff.” – Chuck, about cave exploration; “Like so many...I mean, no disrespect, but I hate you.” – Chuck, mocking detractors, 41:01). Neil delivers deep scientific concepts with clear analogies, while Chuck brings levity and relatability.

Final Takeaway

A classic StarTalk “cosmic queries” episode: big ideas broken down for everyone, playful yet profound, and anchored by the core StarTalk message—keep looking up, question everything, and laugh while you do it.