Podcast Summary: The Rest Is Classified

Episode: Introducing: The Rest Is Science
Hosts: Michael Stevens & Professor Hannah Fry (guest hosts)
Release Date: December 11, 2025
Podcast Network: Goalhanger

Overview:

This special episode introduces "The Rest Is Science," a new show by Michael Stevens and Professor Hannah Fry. Picking up the mic from "The Rest Is Classified," they promise to dissect familiar phenomena and challenge everyday assumptions, with curiosity fueling explorations into the underlying science. The preview episode delves into the concept of gravity—how it’s defined, perceived, and understood from Newton to Einstein, unpacking the evolution of our understanding through analogies, calculations, and playful banter.

Key Discussion Points & Insights

1. Curiosity as the Engine of Science

• Michael and Hannah open by setting their show’s intent: to question even the basics we take for granted and expose the surprising science beneath everyday experiences.
  • "That's what moves science forward. Not the polishing of answers, but the sharpening of questions." – Michael [00:51]
• They invite listeners to join the journey every Tuesday and Thursday to confront and decipher scientific mysteries together.

2. How Would You Explain Gravity to an Alien?

• Prompt: Michael poses, "How would you describe gravity to an alien from another universe that had never experienced gravity?" [01:17]

• Hannah’s answer: It’s a universal attraction between objects with mass—objects simply come together if unimpeded.

  • "Anything with mass ... we sort of imagine gravity as though it's like the Earth is pulling us down. But ... we're also pulling the Earth up." – Hannah [01:47]

• Michael's illustration: Even two baseballs in deep space would eventually move toward one another solely due to gravity, albeit over days.

  • "I once calculated that two baseballs placed in intergalactic space a meter apart would ... collapse in towards each other until they touched ... because of their gravitational attraction." – Michael [02:06]

• Playful debunking of astrology:

  • Astrology’s celestial influence is dwarfed by the basic gravitational interaction with a nearby human.
    • "The gravitational influence of Pisces on you is less than the gravitational influence of the doctor who delivered you on you." – Michael [02:49]

3. Gravitational Attraction Works Both Ways

• Key idea: Every object exerts gravitational pull—not just the bigger ones.
  • Even a dropped pen technically pulls the Earth upward, though by an unimaginably tiny amount.
  • "If you dropped a pen from six feet up, it actually pulls the Earth up towards it. 9 trillionths the width of a proton." – Michael [03:20]

4. Newton vs. Einstein: Evolving Views on Gravity

Newtonian Gravity:

• Newton posited gravity as a force accelerating objects toward one another. The famous “force equals mass times acceleration” rule.
  • "Everything you're describing so far is essentially like a Newtonian view of gravity ... objects accelerating towards each other." – Hannah [05:01]
• Problems with Newton’s model:
  • Immediate gravitational effects don’t consider the speed-of-light limit
  • Mercury's orbit (“precession of the perihelion”) didn’t fully fit the equations.

Einstein’s General Relativity:

• Einstein reimagined gravity as curvature in the fabric of spacetime, not a force but a consequence of objects warping this fabric.
  • "Maybe gravity is just a change in the shape of space. Time is really gigantic, gigantic." – Michael [09:10]
  • "If you got a magical wand and you made the sun disappear immediately ... there would be this ripple that was sent out ... at the speed of light." – Hannah [07:56]
• The “crumpled curtain” analogy:
  • Mass bends space and time—just as a bowling ball stretches a rubber sheet—and objects move along this curvature.

Einstein’s model explained Mercury’s orbit precisely: - "He absolutely nailed it ... he was happy for days after he looked at those calculations." – Hannah [08:34]

5. Everyday Consequences of Curved Spacetime

• Gravity isn’t constant everywhere on Earth—it's affected by altitude.

  • "Boulder in Colorado ... 9.796 meters per second. Greenwich ... 9.812." – Hannah [11:08]
  • Meaning: In Boulder, you’re less attracted to the Earth's center than in Greenwich due to the inverse square law.

• Time runs differently:

  • Gravity’s warping of spacetime affects the passage of time.
  • "Time travels slower in Greenwich than it does in Boulder ... about 5.6 microseconds a year. So ... you are aging faster than me." – Hannah [11:26]

Notable Quotes & Memorable Moments

• "We are gravitationally attracted to each other right now. It cannot overcome the air ... but yet we are attracted." – Michael [02:12]

• "People are like, oh, so you're an Aquarius? And I'm like, no, I'm a schnit cookie. Because Dr. Schnitcookie was there, influencing me to catch you at a physical level." – Michael [03:04]

• "If you take something that has more matter, the amount that the Earth would move would change too." – Hannah [04:30]

• "If the sun suddenly vanished, we wouldn't know about it at all [immediately]." – Michael [06:48]

• "It's the crumpling of the curtain. That's a really nice way to do it." – Hannah [10:16]

Timestamps for Key Segments

• [00:51] – The philosophy of science and curiosity
• [01:17] – Gravity explained for an alien
• [02:06] – Gravity’s effect on everyday objects and cosmic ones
• [03:20] – A pen’s pull on the Earth: scale of gravitational forces
• [05:01] – Newton's laws and their limitations
• [07:56] – Einstein's insight and Mercury's mysterious orbit
• [09:10] – Curved spacetime and analogies ("crumpled curtain")
• [11:08] – Altitude, gravity variation, and time dilation

Tone & Language

The dialogue is accessible, playful, and filled with relatable analogies, making profound physics approachable and engaging for general listeners.

For Listeners Who Missed the Episode:

This energetic preview gives you a taste of what "The Rest Is Science" promises: deep explorations of everyday science, friendly banter, and a knack for unraveling the world's workings—starting with how and why gravity, from apple falls to Mercury’s orbit, shapes our universe (and even the way we age).