StarTalk Radio – "Things You Thought You Knew: Oatmeal Sun"

Host: Neil deGrasse Tyson
Co-Host: Chuck Nice
Date: August 26, 2025

Episode Overview

In this lively "Things You Thought You Knew" episode, Neil deGrasse Tyson and comedian Chuck Nice embark on a scientific journey that links seemingly unrelated household phenomena—making toast, boiling oatmeal, and launching rockets—to reveal the universal principles of thermodynamics and physics that underpin them all. As always, science collides with pop culture and humor for an illuminating and entertaining exploration.

Key Discussion Points & Insights

1. The Physics of Toasting Bread

• Why Doesn’t Bread Brown at First?

  • Moisture Content Holds Back Browning: Bread doesn’t brown until its surface moisture evaporates. The bread “just sits there” mostly unchanged until late in the toasting process ([04:30]–[04:42]).

  • Neil Tyson: “If you observe the bread, most of the time, 90% of the time...it's in the toaster, [it] doesn't change color at all." ([04:30])

• Temperature Limit due to Water

  • Bread can't get hotter than 212°F/100°C (boiling point of water) while water is present, inhibiting browning reactions.

  • Neil Tyson: "Because it can't change color as long as it's moist. Because the highest temperature you can heat the bread is 212 degrees. And that's not hot enough to toast the bread." ([04:44])

• Analogy to Burning Green Logs

  • Just like wet logs won’t ignite until they’re dry, bread only browns once it’s lost enough water ([05:10]).

• The Sudden Browning

  • Once moisture is gone, browning (Maillard and caramelization reactions) happens quickly in about the last minute ([06:11]–[06:47]).

  • Chuck Nice: “If it were a graph, it would bump along the bottom, and then all of a sudden, it shoots straight up. Almost.” ([07:30])

Notable Moment:

• Chuck recalls real-life toaster experience:
  • “I said, what's taking this toast so damn long? ... And I went back, and the toast was brown.” ([07:36]–[08:09])

2. Boiling Water in Paper Cups & Why Oatmeal Boils Over

• Why Can You Boil Water in a Paper Cup?

  • A paper cup in a flame won’t burn if it’s filled with water, because the cup's temperature is limited by water’s boiling point until all water is gone ([08:15]–[08:25]).

  • Neil Tyson: “The hottest temperature the paper can get? The temperature of the water.” ([08:30])

• Thermodynamics of Boiling Over:

  • Pure water rarely boils over, but oatmeal is infamous for it.

  • In oatmeal, water vapor/steam can't escape easily, forcing the oatmeal to expand and spill out as steam tries to find a path–a process likened to the Sun becoming a red giant ([22:20]–[25:32]):

    • Neil Tyson: "Oatmeal boils over for the same reason the Sun gets big: the energy can't get out, and it has to thin things up above it so that the energy can find its way out." ([25:21])

Timestamped Segment:

• Sun vs Oatmeal Analogy: ([23:29]–[25:32])
  • When the core of the Sun burns out its hydrogen, extra energy gets trapped until it “busts out” by expanding, just like oatmeal boiling over.

3. Heat Transfer in Cooking

• Conduction: Heat is transferred molecule by molecule (e.g., a hot pan handle) ([18:03]).
• Convection: In water, blobs of hot water rise, transferring heat more efficiently ([19:07]–[19:38]).
• Why Raisins Jump in Boiling Water: They follow convection currents ([19:51]–[20:06]).
• Boiling vs. Browning: Discussing how only when heat surpasses the evaporative barrier—when water is gone or surface dry—does browning occur.

Notable Moment:

• Boiling and "farting" analogy:
  • Chuck Nice: “Boiling water is really just... water farting, basically.” ([21:24])

4. Air Fryers & Wind Heat Factor

• Air Fryers as Air Toasters:
  • Fast-moving hot air in air fryers rapidly removes moisture, speeding up browning ([10:44]–[11:26]).
  • Neil Tyson: “They're really air toasters...if it didn't have any oil, it's just a fast toaster.” ([11:07]–[11:30])

5. Experiment Suggestions

• Pre-toasting Bread:
  • Compare toasting time between fresh and stale (dried) bread: dry bread toasts much faster ([11:51]–[12:21]).
• Rescuing Burnt Toast:
  • Scrape off the surface and the underlying bread remains edible ([13:03]).

6. Rocket Science: How Rockets Differ from Airplanes

• Rockets vs. Planes: Oxidizer

  • Rockets carry their own oxidizer, planes use atmospheric oxygen ([28:00]).

• Solid Rocket Boosters:

  • Burn outward from the center; unrecoverable once ignited ([28:56]–[29:36]).

• Space Shuttle Main Engine:

  • Uses liquid hydrogen and oxygen, produces water as a byproduct ([30:09]–[30:38]).
  • Brief discussion on possible use of hydrogen fuel for clean energy and its engineering challenges ([30:48]–[31:01]).

Notable Moment:

• Water as Rocket Byproduct:
  • Neil Tyson: “So you chill [hydrogen and oxygen] so that it liquefies. ...And what is the waste product? ...Water. There it is.” ([30:13]–[30:38])

7. Why Rockets Fly Sideways: Achieving Orbit

• Orbit is Not "Up," It's "Sideways":

  • Half the rocket's energy goes into accelerating sideways (downrange) to stay in orbit, not just escaping Earth's gravity ([31:38]–[32:03]).

  • Neil Tyson: “For everything that goes in orbit, half the energy of that rocket is not there to get it up into space, half...is to take it downrange.” ([31:38])

• Orbit Explained:

  • Once moving fast enough sideways, the rocket “falls” around the Earth, matching Earth's curvature ([32:03]–[33:07]).

• Difference Between Suborbital and Orbital Flight:

  • Bezos and Branson went suborbital—up and then down, no orbit. Elon Musk reached orbit ([33:48]–[34:24]).

8. Bonus Deep Cut: The Brachistochrone Problem

• Fastest Path Under Gravity:
  • The quickest descent path isn’t a straight line but a curve (like a roller coaster). This same logic shapes the initial trajectory of launching a rocket for optimal efficiency ([35:04]–[36:19]).
• Fun Physics History:

  • Bernoulli brothers formulated and solved this in the 18th-century.

  • Neil Tyson: “If you flip it up, that is the trajectory to launch a rocket. ...That is a physics mic drop right there.” ([36:19]–[36:29])

Notable Quotes & Moments

• On Toasting Bread:
  • “The heat is like, 'Get out of there, water molecules! Get out, get out!'” – Neil Tyson ([05:48])
• On Cooking Oatmeal and the Sun:
  • “Oatmeal boils over for the same reason the Sun gets big: the energy can't get out.” – Neil Tyson ([25:21])
• Rocket Trajectory Mic Drop:
  • “If you flip it up, that is the trajectory to launch a rocket. ...That is a physics mic drop right there.” – Chuck Nice ([36:19])
• Humor Highlight:
  • “Boiling water is really just... water farting, basically.” – Chuck Nice ([21:24])
• On Real-life Toaster Science:
  • “I lived this experience.” – Chuck Nice ([08:13])

Timestamps for Key Segments

• [02:25] – Beginning the toast science explainer
• [05:10] – Moisture analogy with green logs
• [06:47] – Nonlinear toasting graph analogy
• [08:25] – Boiling water in a paper cup
• [10:44] – Air fryer/air toaster discussion
• [11:51] – Bread moisture and toast experiments
• [13:03] – Salvaging burnt toast
• [17:20] – Boiling water and convection currents
• [22:20] – Why oatmeal boils over and the red giant sun analogy
• [25:21] – The energy escape principle for oatmeal and the sun
• [28:00] – Rockets vs. airplanes and rocket oxidizers
• [30:38] – Water as rocket exhaust and hydrogen fuel cell mention
• [31:38] – The true nature of orbit and sideways launches
• [33:48] – The Bezos/Branson suborbital distinction
• [35:04] – Brachistochrone problem and rocket trajectories
• [36:19] – Physics "mic drop" moment

Tone & Style

True to StarTalk's signature style, the episode blends clear scientific explanations with pop-culture references and humor. Neil deGrasse Tyson delivers sound science with metaphors and food analogies, while Chuck Nice injects wit, playfulness, and relatable real-life observations. The mood remains accessible, curious, and frequently laugh-out-loud funny.

Summary Takeaway

From your toaster to the sun to the launchpad, temperature, energy, and the laws of physics govern not just breakfast but the universe itself. Whether boiling oatmeal or launching rockets, understanding what’s really happening “under the hood” reveals just how connected everyday phenomena are to cosmic principles.

Final Word:
Neil deGrasse Tyson: “As always, keep looking up.” ([37:20])