MinutePhysics

The Genius of Thorium Breeder Reactors

MinutePhysics — Tue, 12 May 2026 17:04:01 +0000

This video looks at how thorium reactors generate more fissile material than they consume!

REFERENCES
- Thermal breeder reactors: https://doi.org/10.1146/annurev.ns.22.120172.001533
- Thorium reactor: https://www.ans.org/pubs/proceedings/article-59521/
- World Nuclear Association: https://world-nuclear.org/information-library/current-and-future-generation/thorium

Link to Patreon Supporters: http://www.minutephysics.com/supporters/

Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute!

Created by Henry Reich
Produced by Joshua Chawner

Newcomb's Paradox - Full Conversation with Derek & Henry | Nebula Plus

MinutePhysics — Wed, 15 Apr 2026 22:12:57 +0000

The full followup conversation between me and Derek (of Veritasium) about my video following up on the Veritasium video on Newcomb's Paradox https://nebula.tv/videos/minutephysics-the-problem-with-newcombs-paradox

The Problem With Newcomb's Paradox

MinutePhysics — Wed, 15 Apr 2026 20:24:57 +0000

A response to Veritasium's video on Newcomb's Paradox. See my full followup conversation with Derek here on Nebula: https://nebula.tv/videos/minutephysics-newcombs-paradox-full-conversation-derek-henry

See Derek's original video over on the Veritasium channel: https://www.youtube.com/watch?v=Ol18JoeXlVI

REFERENCES

Newcomb's Paradox: https://doi.org/10.1007/978-94-017-1466-2_7
Quantum solution: https://doi.org/10.48550/arXiv.quant-ph/0202074
Quantum causality: https://doi.org/10.1103/PhysRevX.7.031021
https://www.pokutta.com/blog/newcomb-four-lenses/
https://scottaaronson.blog/?p=30
Veritasium video references

Link to Patreon Supporters: http://www.minutephysics.com/supporters/

And Facebook: http://facebook.com/minutephysics

Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute!

Created by Henry Reich

Produced by Joshua Chawner

Do you understand ISO?

MinutePhysics — Wed, 11 Mar 2026 21:53:57 +0000

This video explains how ISO in digital cameras is very different from what most people imagine, and how you can use this knowledge to take less noisy photos and videos!

REFERENCES

Sensor Analysis Primer: https://www.photonstophotos.net/GeneralTopics/Sensors_&_Raw/Sensor_Analysis_Primer/Photographic_Dynamic_Range_Shadow_Improvement.htm
Image sensors explained: https://www.canon-europe.com/pro/infobank/image-sensors-explained/

Link to Patreon Supporters: http://www.minutephysics.com/supporters/

And Facebook: http://facebook.com/minutephysics

Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute!

Created by Henry Reich

Produced by Joshua Chawner

Chapters

0:00 Misunderstanding ISO

1:54 ISO Explained

3:20 Why Even Have ISO?

4:52 What Actually Creates Noise

7:12 ISO Step-by-Step Guide!

8:36 ISO Caveats

Does Quantum Mechanics solve the Fermi Paradox?

MinutePhysics — Wed, 11 Feb 2026 21:52:50 +0000

This video explains how the Fermi Paradox - the fact that aliens should mathematically be abundant in the universe and yet we haven't heard from any - actually makes sense when you take into account quantum communication.

REFERENCES

On Interstellar Quantum Communication and the Fermi Paradox: https://doi.org/10.48550/arXiv.2408.02445
Quantum coherence to interstellar distances: https://doi.org/10.48550/arXiv.2009.00356
Exponential Separation of Quantum and Classical One-Way Communication Complexity for a Boolean Function: https://doi.org/10.48550/arXiv.quant-ph/0607174
Classical Interaction Cannot Replace a Quantum Message: https://doi.org/10.48550/arXiv.quant-ph/0703215

The REAL Reason Asteroids Are No Longer Planets

MinutePhysics — Thu, 22 Jan 2026 18:14:54 +0000

This video is about the interesting and often-misunderstood story of the asteroids, and how they lost their planet-hood status; more recently than you may think!

REFERENCES

Link to Patreon Supporters: http://www.minutephysics.com/supporters/

And Facebook: http://facebook.com/minutephysics

Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute!

Created by Henry Reich

Produced by Joshua Chawner

Chapters

0:00 Intro

0:23 Asteroid Planet Discovery

1:07 Asteroid Planet Reaction

1:48 Why Asteroids are Not Planets

3:09 Demotion of the Asteroids

An Argument The Moon is a PLANET?

MinutePhysics — Mon, 22 Dec 2025 18:31:20 +0000

This video is about how the International Astronomical Union's definition for a planet is flawed, even if you take it at face value! The moon almost counts as a planet according to their definition, even though they don't want it to...

REFERENCES MinutePhysics video about the moon's orbit: https://nebula.tv/videos/minutephysics-the-moons-orbit-is-weird

IAU 2006 Resolutions: https://iauarchive.eso.org/news/pressreleases/detail/iau0603/

Paper arguing moon satisfies IAU criteria: https://doi.org/10.4236/ijaa.2017.74024 https://doi.org/10.3847/PSJ/ad4edd

BEST paper about planet definition history: https://doi.org/10.1016/j.icarus.2021.114768

https://doi.org/10.1017/S1539299600013289

IAU exoplanet working definition: https://doi.org/10.1017/S1539299600013289

How Can We Prove The Moon Orbits the Earth?

MinutePhysics — Wed, 03 Dec 2025 19:49:55 +0000

The MinutePhysics Tshirt bundle is available now! https://store.dftba.com/products/physics-t-shirt-bundle

How do we truly know if something is orbiting something else rather than being a binary companion? You may be familiar with the barycenter test, but you may not have heard of the better "Trojan test"!

The Physics of Fogbows (aka White Rainbows)

MinutePhysics — Fri, 24 Oct 2025 18:36:00 +0000

If you wander outside on a misty morning you may come across a white rainbow - called a fogbow! White rainbows need three things to form: mist, the sun, and you. To find a white rainbow, go out when the Sun is low in the sky, like in the morning or evening. You want the Sun to be behind you so that a ~40 degree angle from the droplet to you and the sun is achievable. You'll need to be in a very thin fog, thin enough that the sun shines through but thick enough to reflect the sun's light back. Look away from the sun (the same way you do with a regular rainbow).

REFERENCES:

Mie theory, Airy theory, and the natural rainbow - https://opg.optica.org/ao/abstract.cfm?uri=AO-37-9-1506

Physically-based simulation of rainbows - https://dl.acm.org/doi/abs/10.1145/2077341.2077344

Veritasium video about rainbows: https://www.youtube.com/watch?v=24GfgNtnjXc

Why Do Wind Turbines Have Three Blades?

MinutePhysics — Sat, 04 Oct 2025 14:00:15 +0000

Wind turbines are a successful and popular method to create clean energy. But why do almost all of them have 3 blades? Here are 3 reasons.

Bonus Content: Common Moon Mistakes | Nebula Plus

MinutePhysics — Fri, 03 Oct 2025 16:45:32 +0000

Some discussion about material that got cut from the "Common Moon Mistakes" video.

The Most Common Moon Mistakes

MinutePhysics — Fri, 03 Oct 2025 16:39:32 +0000

Common mistakes that people make when illustrating the moon.

Draining the Oceans is HARD

MinutePhysics — Fri, 05 Sep 2025 16:19:14 +0000

It's hard to drain the oceans because it's a nonlocal phenomenon. Luckily there's a clever algorithm that's similar to the "paint bucket" tool in photoshop or other image editing software that allows us to figure out where remnant ocean basins will be.

White Balance is Broken

MinutePhysics — Tue, 05 Aug 2025 06:23:14 +0000

White Balance in digital photo and video cameras (even professional cinema cameras costing nearly $100,000) isn't implemented correctly - the difference between 3000K and 3100K is WAY different than between 9000K and 9100K!

The Physics of Dissonance

MinutePhysics — Fri, 18 Jul 2025 18:05:41 +0000

The physics of why certain notes and chords sound in tune together and why others don't, and how that can lead to different types of music in different cultures around the world.

The Teleprompter Paradox

MinutePhysics — Fri, 28 Feb 2025 18:38:45 +0000

If you put a teleprompter close enough to read, the audience will see your eyes moving. So you put it farther away, and then you can't read it. What's the solution? Is there one?

The Chart They're ALL Missing

MinutePhysics — Fri, 22 Nov 2024 17:28:26 +0000

I couldn't believe all these major spreadsheet software apps, and other math apps, are missing this seemingly simple type of chart!!

I'm Giving Away 14 Years of Drawings

MinutePhysics — Fri, 01 Nov 2024 15:33:48 +0000

Go to https://patreon.com/minutephysics to support MinutePhysics on Patreon! I'm sending everyone who's a supporter by the end of November a print of a drawing as a thank you, and everyone above the "Special Relativity" level will be sent an original drawing!

The Moon's Orbit is WEIRD

MinutePhysics — Wed, 02 Oct 2024 16:14:45 +0000

We think of the moon as orbiting the earth, following a spiraling trajectory as the earth itself orbits the sun. But this is wrong. Not only is the moon's orbit NOT a spiral... there's an argument that the moon actually orbits the sun, not the earth! The moon's trajectory is more like a 12-sided polygon with curved corners than it is a spiral or even a wiggly line.

Does Pressure Keep the Deep Ocean From Freezing?

MinutePhysics — Mon, 26 Aug 2024 15:38:48 +0000

Pressure can melt ice - like, you only need 500 times atmospheric pressure to melt ice down to negative four degrees celsius. If you have 1000 times atmospheric pressure (like at the bottom of the Mariana trench), then you'll melt ice down to around negative nine celsius. But that's for fresh water. For salty sea water, things are different.

The Color Temperature Paradox

MinutePhysics — Tue, 23 Jul 2024 23:09:09 +0000

If you take a piece of white paper into different lighting conditions, it will be an objectively different color in each situation, but our brains are clever enough to make us feel like it's still white - it's still the same piece of paper, after all. To match our experience, cameras have to do this, too, "balancing" the colors of an image so that a white object looks white under a given light, rather than some other color. And the typical unit to measure the color of a light is the Kelvin. Which is weird, because Kelvin is a unit for measuring temperature, not color. What temperature and the color in a photograph have to do with each other comes down to history and physics.

I Ranked All the Eclipses in the Solar System

MinutePhysics — Fri, 05 Apr 2024 04:22:41 +0000

Solar eclipses don't just happen here on earth - moons of other planets also pass between those planets and the sun, resulting in various types of solar eclipses on Mars, Jupiter, Saturn, Uranus, Neptune, and even non-planets like Pluto, Eris and various asteroids. So, where are the best eclipses in the solar system? For that, we need a tier list.

Why Do Eclipses Travel From WEST to EAST?

MinutePhysics — Mon, 01 Apr 2024 15:44:14 +0000

The sun rises in the east, the moon rises in the east, and the stars rise in the east... but solar eclipses, oddly, come from the west. If total eclipses are caused by the sun and the moon, why don't they behave like the sun and the moon?

Why Aren't There Eclipses Every Month?

MinutePhysics — Thu, 21 Mar 2024 20:28:25 +0000

The moon orbits the earth once per month, which means the moon is on the sun side of the earth every month. So... "why aren't there eclipses every month?" is a question we will answer in this video!

The LAST Eclipse in History

MinutePhysics — Thu, 14 Dec 2023 18:55:11 +0000

We are in the Golden Age of Solar Eclipses, but only for the moment. In fact, I'd argue we're already past peak solar eclipse and it's all downhill from here.

Explaining Those Ghostly Eclipse Photos

MinutePhysics — Wed, 06 Dec 2023 06:37:48 +0000

A lot of people took pictures of the recent solar eclipse in North America and got photos where there's a ghostly image of the eclipse floating in the sky nowhere near where the sun is!

The short explanation is that the ghostly eclipse images are lens flares: the thing that happens when you point a camera towards a particularly bright light source and you get a glow or streaks or disks... or eclipses?

Are Magnetic Guitar Picks A Scam?

MinutePhysics — Wed, 14 Jun 2023 16:39:47 +0000

I was sent a magnetic guitar pick to review, so I reviewed it. Does it work? How? Why? What's the physics of electric guitar strings and pickups? Are magnets useful? Do they affect the strings? The pickups?

But Why Do Geosynchronous Orbits Even Exist?

MinutePhysics — Thu, 22 Dec 2022 03:55:23 +0000

This video is about the physics of geosynchronous and geostationary orbits, why they exist, when they don't, when they're useful for communication/satellite TV, etc.

REFERENCES

fraction of a sphere that's visible from a given distance
https://math.stackexchange.com/questions/1329130/what-fraction-of-a-sphere-can-an-external-observer-see

Orbital period
https://en.wikipedia.org/wiki/Orbital_period

Kepler's third law
https://en.wikipedia.org/wiki/Kepler%27s_laws_of_planetary_motion#Third_law

Kepler's 3rd law (which can be derived from Newton's law of gravitation and the centripetal force necessary for orbit as mr\omega^2=G\frac{mM}{r^2}, and using \omega=\frac{2\pi}{T}) is
T = 2pi Sqrt(r^3/(GM)) where M is the mass of the central object, G is the gravitational constant. Alternatively, we can solve for r, r = (T^2/(4pi^2) GM)^(1/3) ~ T^(2/3)/M^(1/3) = (T^2/M)^(1/3).

There is a limit (kind of like the Roche limit but for rotations). A rotating solid steel ball or other chunk of metal that has tensile strength (ie that isn't just a pile of stuff held together by gravity like most planets) would be able to spin faster.

Calculate how much of a planet's surface you can see from a given geosynchronous orbit/radius? (Obviously for lower ones you can see less, etc) - d/(2(R+d)) where d is distance to surface, ie, R is sphere radius, R+d is object radius from sphere center.

Let's plug that in with r being the geostationary orbit radius. That is, we have \frac{1}{2} \left(1- \left(\frac{4 \pi^2 R^3}{T^2 G M }\right)^{1/3}\right)

Average density of a sphere \rho is given by \rho =M/(\frac{4}{3}\pi R^3), ie \rho=\frac{3M}{4 \pi R^3} aka

\frac{M}{R^3}=\frac{4}{3}\pi \rho.

So we can convert the "fraction of planet surface seen" to

\frac{1}{2} \left(1- \left(\frac{3 \pi}{G \rho T^2}\right)^{1/3}\right)

So as either \rho or T\to \infty, the fraction goes to a maximum of \frac{1}{2}. And the point of "singularity" where the orbit coincides with the surface is where G\rho T^2=3\pi, aka \rho=\frac{3\pi}{GT^2}. For a rotation period of 3600s, that corresponds to a density \rho \approx 11000kg/m^3, which is roughly twice the density of the earth. For a rotation period of 5400s, we have \rho\approx 4800kg/m^3, which is basically the density of the earth.

Alternately, if we plug the density of the earth in to an orbit of period 5400s, we get as a fraction of the planet seen:

\frac{1}{2} \left(1- \left(\frac{3 \pi}{G \rho T^2}\right)^{1/3}\right) = 0.02

aka 2\% of the earth's surface.

Explaining the SECRET of Penrose Patterns

MinutePhysics — Wed, 30 Nov 2022 23:09:24 +0000

This video is about a better way to understand Penrose tilings (the famous tilings invented by Roger Penrose that never repeat themselves but still have some kind of order/pattern).

REFERENCES
Explore Penrose and Penrose-like patterns: https://aatishb.com/patterncollider

Video by Derek Muller/Veritasium about Penrose Patterns: https://www.youtube.com/watch?v=48sCx-wBs34

Music algorithmically generated, algorithm designed by Henry Reich

N.G. de Bruijn’s paper introducing the pentagrid/Penrose idea: https://www.math.brown.edu/reschwar/M272/pentagrid.pdf

De Bruijn, N.G., 1981. Algebraic theory of Penrose’s non-periodic tilings of the plane. Kon. Nederl. Akad. Wetensch. Proc. Ser. A, 43(84), pp.1-7.

Here are some excellent in-depth references on how to construct Penrose Tiles Using the Pentagrid Method:
Penrose Tilings Tied up in Ribbons by David Austin: http://www.ams.org/publicoutreach/feature-column/fcarc-ribbons
The Empire Problem in Penrose Tilings by Laura Effinger-Dean: http://www.cs.williams.edu/~bailey/06le.pdf
Pentagrids and Penrose Tilings by Stacy Mowry & Shriya Shukla: https://web.williams.edu/Mathematics/sjmiller/public_html/hudson/HRUMC-Mowry&Shukla_Pentagrids%20and%20Penrose.pdf
Penrose Tiling by Andrejs Treibergs: http://www.math.utah.edu/~treiberg/PenroseSlides.pdf
Algebraic Theory of Penrose's Non-Periodic Tilings of the Plane by N. G. de Bruijn: https://www.math.brown.edu/reschwar/M272/pentagrid.pdf
Particularly good and helpful, and (we think) an undergrad thesis which is impressive!: http://www.cs.williams.edu/~bailey/06le.pdf

An interesting popular science read on the discovery on quasicrystals and their connection to Penrose Tilings:
The Second Kind of Impossible by Paul Steinhardt: https://bookshop.org/books/the-second-kind-of-impossible-the-extraordinary-quest-for-a-new-form-of-matter-9781476729930/9781476729930

The Ice/Water Paradox

MinutePhysics — Thu, 13 Oct 2022 21:33:29 +0000

Freezing water expands. What if you don’t let it?

MinutePhysics

The Genius of Thorium Breeder Reactors

Newcomb's Paradox - Full Conversation with Derek & Henry | Nebula Plus

The Problem With Newcomb's Paradox

Do *you* understand ISO?

Does Quantum Mechanics solve the Fermi Paradox?

The REAL Reason Asteroids Are No Longer Planets

An Argument The Moon is a PLANET?

How Can We Prove The Moon Orbits the Earth?

The Physics of Fogbows (aka White Rainbows)

Why Do Wind Turbines Have Three Blades?

Bonus Content: Common Moon Mistakes | Nebula Plus

The Most Common Moon Mistakes

Draining the Oceans is HARD

White Balance is Broken

The Physics of Dissonance

The Teleprompter Paradox

The Chart They're ALL Missing

I'm Giving Away 14 Years of Drawings

The Moon's Orbit is WEIRD

Does Pressure Keep the Deep Ocean From Freezing?

The Color Temperature Paradox

I Ranked All the Eclipses in the Solar System

Why Do Eclipses Travel From WEST to EAST?

Why Aren't There Eclipses Every Month?

The LAST Eclipse in History

Explaining Those Ghostly Eclipse Photos

Are Magnetic Guitar Picks A Scam?

But Why Do Geosynchronous Orbits Even Exist?

Explaining the SECRET of Penrose Patterns

The Ice/Water Paradox

Do you understand ISO?