Paul Sutter

What Would Happen if the Sun Stopped? Part 4: Black Hole Sun

June 18, 2026

Switch off fusion and, for ten thousand years, nothing happens. Then the Sun begins a slow, strange death: shrinking, briefly brightening, and coasting on gravitational heat for tens of millions of years. And the neutrinos give the whole thing away in just eight minutes.

What Would Happen if the Sun Stopped? Part 3: The Photon Traffic Jam

June 17, 2026

A photon born in the Sun's core takes around 100,000 years to fight its way to the surface, bouncing through a random walk so inefficient that the light on your face is older than human civilization. Why the Sun's surface is a hundred-millennia-delayed broadcast.

What Would Happen if the Sun Stopped? Part 2: Kelvin and Helmholtz at the Ready

June 16, 2026

How can the Sun keep shining with its furnace switched off? Two nineteenth-century aristocrats, Helmholtz and Lord Kelvin, worked out the answer mostly by accident. It comes down to stored heat, gravitational shrinking, and the strange self-regulating thermostat of hydrostatic equilibrium.

What Would Happen if the Sun Stopped? Part 1: The Infernal Reservoir

June 15, 2026

If the Sun's fusion shut off right now, you would not notice for a very long time. The first stop is understanding the Sun itself: a vast pile of gravitating matter where fusion is so absurdly inefficient that, pound for pound, a compost heap beats it.

Why Can't the Universe Be Cyclic? Part 4: When a Good Idea Meets Bad Data

June 09, 2026

The ekpyrotic universe is a beautiful idea that runs headlong into the data. From hand-waved singularities and assumed dark energy to the killer blow from Planck and WMAP measurements of the cosmic microwave background, here is why nature has so far voted against it.

Why Can't the Universe Be Cyclic? Part 3: The Ekpyrotic Universe and Its Bouncing Branes

June 08, 2026

The ekpyrotic theory tries to beat inflation with bouncing higher-dimensional branes, no singularity, and a universe that has always existed. A tour of the prettiest version of the idea and how it claims to handle flatness, dark energy, and the entropy that doomed earlier cyclic models.

Why Can't the Universe Be Cyclic? Part 2: The Awkward Triumph of Inflation

June 07, 2026

Inflation is awkward, possibly not even a proper theory, and it has reigned over cosmology for forty years anyway. Here is what it claims, the flatness, horizon, and monopole problems it solves, the structure-formation prediction it nailed, and the deep problems it still cannot escape.

Why Can't the Universe Be Cyclic? Part 1: The Lure of the Eternal Universe

June 06, 2026

A look at why a cyclic, eternally repeating universe is such an appealing idea, and why the first serious attempt to build one, Richard Tolman's 1930s model of endless big bangs and big crunches, collapsed under the weight of entropy. The Big Bang keeps demanding a beginning.

Is Dust the Best Thing in the Universe? Part 4: We Owe Dust Our Lives

May 22, 2026

No dust, no way to cool a collapsing gas cloud. No way to cool it, no stars. No dust, no first rung on the ladder from grain to pebble to planet. The substance I spent two articles complaining about turns out to be the substance that makes me possible.

Is Dust the Best Thing in the Universe? Part 3: Tiny Chemistry Labs

May 22, 2026

Two hydrogen atoms can't form an H2 molecule on their own in empty space. They need a surface. The universe has only one surface available, and it's something I have just spent two articles complaining about.

Is Dust the Best Thing in the Universe? Part 2: The Astronomer's Headache

May 21, 2026

Dust scatters light, absorbs light, re-emits light, and ruins everything. It's why our maps of the Milky Way were wrong before 1930, and it's why one of the biggest cosmological announcements of the 2010s quietly evaporated.

Is Dust the Best Thing in the Universe? Part 1: The Apology Begins

May 20, 2026

Years of grievance against dust. It ruins lungs, suits, rovers, and Mars missions. The first installment of an apology, sort of, to the most annoying substance in the cosmos.

What If the Universe Had No Beginning? Part 4: The Reckoning

May 19, 2026

No quantum gravity. The wrong peak in the wave function. Boltzmann Babies. Roger Penrose pointing out that the arrow of time was smuggled in through the back door. The no-boundary proposal is beautiful. It is also possibly wrong in many specific ways.

What If the Universe Had No Beginning? Part 3: A Universe From Nothing

May 18, 2026

Run Hawking's machinery and out pops something startling: the most likely universe looks an awful lot like ours, complete with inflation, a low-entropy beginning, and an arrow of time. All of cosmology, falling out for free. Almost.

What If the Universe Had No Beginning? Part 2: No Boundary, No Problem

May 17, 2026

Hawking faced a question with no answer hiding behind it. The best boundary condition for the universe, he decided, was that there was no boundary at all. To make that statement into physics, he had to do something deeply strange to time.

What If the Universe Had No Beginning? Part 1: A Wave Function for the Universe

May 16, 2026

The equations of general relativity give up at the singularity. Decades before Stephen Hawking dared to guess what came before, John Wheeler and Bryce DeWitt built the strange mathematical machinery that would make the question askable in the first place.

What Happens When Light Goes Boom? Part 4: What Brad Bradington Is Good For

April 19, 2026

Cherenkov radiation isn't just a beautiful phenomenon. It turns up in nuclear reactors, in the upper atmosphere, in gamma ray telescopes on three continents, in a cubic kilometer of Antarctic ice, and in hospital imaging suites. Here's what a light boom is actually good for.

What Happens When Light Goes Boom? Part 3: Brad Bradington Sprints

April 18, 2026

We have the crowd. We have the star. Now it's time to put them together. Here's exactly what happens — and why — when a charged particle outruns the local speed of light in a material. Also: why it's always blue.

What Happens When Light Goes Boom? Part 2: The Crowd, the Molasses, and the Speed of Light (Sort Of)

April 17, 2026

Before Brad Bradington can sprint down the red carpet, we need to understand the crowd. Specifically, we need to understand why a crowd of atoms and molecules slows down light — and why that creates a loophole that changes everything.

What Happens When Light Goes Boom? Part 1: The Scientist Who Stared at a Glow

April 16, 2026

In 1934, a Soviet physicist named Pavel Cherenkov shone gamma rays into a bottle of water and noticed a faint blue glow. So had others before him. They all shrugged and moved on. Cherenkov didn't. What he found — by refusing to dismiss something he didn't understand — turned into one of the most useful phenomena in modern physics.

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