Posts
Twenty-eight so far. Each one is a single page with both versions inside.
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80 picograms: a speck that could destroy 5% of the observable universe
About the mass of one red blood cell, squeezed into a bubble in exactly the wrong way. The physics is real. How it would happen, and why you can still sleep tonight.
~24 min Simple · ~26 min FullRead -
Maybe the universe isn't expanding. Maybe you're shrinking.
Every measurement of cosmic expansion has a twin story in which space sits still and all matter slowly shrinks, and no experiment can tell the two apart. What that says about rulers.
~24 min Simple · ~36 min FullRead -
A 1 followed by 18 quadrillion zeros: how many states your brain can be in
Just printing that number, at 40 digits a second, would take nearly 15 million years. A careful count from 86 billion neurons to the limits of physics, and why a lifetime visits almost none of it.
~15 min Simple · ~25 min FullRead -
400 milliseconds: that might be the whole of your life
If the universe lasts forever, the commonest minds with your exact thoughts could be random flickers holding a single moment, every memory pre-loaded. What one would cost, and why physicists refuse to believe it.
~19 min Simple · ~44 min FullRead -
336 in every cubic centimetre: you're full of ghosts from the first second of time
About 24 million of these neutrinos are inside you right now. They're older than the oldest light, they pass through planets, and nobody has ever caught one. Here's how we know they're real anyway.
~17 min Simple · ~38 min FullRead -
16 tonnes: almost all of your weight is trapped energy
The Higgs field gives you about 1% of your mass. Or 10%. Or 30%, and all three answers are right. The rest is the energy of quarks and gluons, held in by a force that pulls with about 16 tonnes.
~19 min Simple · ~46 min FullRead -
89 billion light-years: fly straight out and you might come back from behind
That's the shortest possible loop around the universe, if space wraps around at all, and nothing we know rules it out. How astronomers hunt the sky for copies of ourselves, and why ours is probably out of view for good.
~17 min Simple · ~31 min FullRead -
1.7 seconds: the photo finish of a 130-million-year race between gravity and light
That gap settled a 200-year-old argument and wiped out a family of dark-energy theories in a single day. Meanwhile a second race was under way: the hunt for the pixels of space.
~19 min Simple · ~54 min FullRead -
31 pixels: how to draw a logo on the Moon, and the law that already bans it
To your eye, the full Moon is a 31-pixel screen. The cheapest readable logo would be about 1,000 km wide and barely darker than the Moon, and the best paint would be a mirror.
~17 min Simple · ~38 min FullRead -
1 centimetre: lift a clock that much and its time runs measurably faster
The best clocks can now tell which floor they're on, so they feel the ground rise and fall with the Moon twice a day. Plus relativity in your GPS, and the vote that ends leap seconds from 2027.
~15 min Simple · ~36 min FullRead -
16 micrograms: the heaviest Schrödinger's cat yet is a sliver of sapphire
In 2023 it vibrated two opposite ways at once, yet its two states were only 1/800 of a proton apart. Why distance, not mass, is the hard part, and where gravity comes in.
~17 min Simple · ~42 min FullRead -
1.7 volts: without relativity, your car wouldn't start
About 1.7 of the 2.1 volts in every car-battery cell exist because electrons inside lead move fast enough for Einstein's rules to matter. The same effect makes gold yellow and keeps mercury liquid.
~17 min Simple · ~36 min FullRead -
1963 (or 1021): nuclear tests left a date stamp in your cells
Bomb tests doubled the carbon-14 in northern air by 1963, so your cells carry the year they were made. A solar storm in 993 dated Viking tree-felling in Newfoundland to 1021. Now fossil fuels are turning the dial back.
~18 min Simple · ~42 min FullRead -
30 minutes on, 2½ hours off: a nuclear reactor nobody built, 2 billion years ago
In 1972 a French uranium plant found uranium missing a sliver of its fuel. The trail led to Gabon, where groundwater once switched the rock itself on and off, and its ashes still test whether the laws of nature change.
~18 min Simple · ~38 min FullRead -
1/8000 of a monopole: magnets with only one pole, by the billion billion, in a cold crystal
Chill the right crystal to about 1 degree above absolute zero and lone north and south poles wander through it. They aren't the monopole physicists are still hunting. They're stranger.
~18 min Simple · ~47 min FullRead -
20 metres per second: heat that travels like sound, and a hot stripe that went colder than the cold around it
Heat normally spreads like ink. In liquid helium it rolls through as a wave, and in April 2026 a stripe of heat on pure graphite briefly went colder than the stripes beside it, at room temperature.
~19 min Simple · ~43 min FullRead -
31.8 hours: ask the Paris pendulum, and that's how long a day lasts
Foucault's pendulum proves the Earth spins once a day, yet it takes 31.8 hours to turn a full circle. The slice it misses is the area of the Earth's cap north of Paris, read as an angle.
~18 min Simple · ~46 min FullRead -
−750 picokelvin: below zero kelvin, and hotter than the Sun
In 1993 a Finnish lab gave the tiny magnets in rhodium atoms a temperature with a minus sign. That isn't colder than nothing: it's hotter than anything with a plus sign. Plus engines above 100%.
~19 min Simple · ~45 min FullRead -
60 nanokelvin: the empty sky is 44 million times hotter than a black hole
Black holes glow, but one with the Sun's mass glows at about 62 billionths of a kelvin. So every black hole we know is still taking in more than it gives out, and none has evaporated a gram yet.
~27 min Simple · ~46 min FullRead -
29%: more than a quarter of a spinning black hole is energy you could mine
Spin a black hole as fast as theory allows and 29% of its mass is spin energy that could, in principle, come back out. How a rock, a wave or a magnetic field could mine it, and what a 2025 bench-top stand-in did and didn't show.
~27 min Simple · ~49 min FullRead -
85%: two players who can't talk beat every crib sheet ever written
Any plan agreed in advance wins this quiz at most 3 rounds in 4. Share entangled particles and the ceiling is 85%. Experiments have beaten 75% since 2015, and still no message passes between the players.
~27 min Simple · ~50 min FullRead -
10 nanometres: empty space squeezes two perfect mirrors with the weight of the sky
Bring two perfect mirrors that close in a cold, empty box and the Casimir force presses them together harder than the air presses on you. Real gold feels an eighth of that, and physicists still tell the cause two ways.
~27 min Simple · ~49 min FullRead -
5 errors in a million: a memory you can't look at that catches its own mistakes
A qubit can't be copied, or even looked at without changing it. Yet a 2026 preprint reports a quantum memory that failed only about 5 times per million rounds of checking. The trick: never ask what it holds.
~25 min Simple · ~46 min FullRead -
0.75 g: physicists dropped antimatter to check it doesn't fall up
In 2023 a CERN team opened a magnetic bottle of antihydrogen and counted which way it went: down, at 0.75 g, give or take a fifth. Why 'up' was always a long shot, and what a 1% measurement could still find.
~28 min Simple · ~48 min FullRead -
511 keV: thunderstorms make antimatter and fire it into space
When an electron meets its antimatter twin, both vanish in gamma rays of exactly 511 keV. Satellites, aircraft and mountain detectors have caught that signal coming from storms, because thunderclouds are natural particle accelerators.
~28 min Simple · ~50 min FullRead -
10¹¹ tesla: a litre of this magnetic field weighs 44,000 tonnes
Near a magnetar, the field's energy alone, through E = mc², is about four million times denser than lead. Atoms get squeezed into needles, and in 2004 one flare ionised Earth's sky.
~27 min Simple · ~46 min FullRead -
0.09 nanometres: blow an electron up to Earth size and it's round to within an atom
In 2023 a clock of trapped molecular ions looked for a lopsided electron and found none. Why a bump would break the symmetry of time, and what that says about particles heavier than the LHC can make.
~27 min Simple · ~46 min FullRead -
1 millimetre a year: a ball of iron about as hot as the Sun's surface is freezing under your feet
Five thousand kilometres down, a ball of iron crystals 1,220 km in radius grows as the liquid around it freezes on. Earthquakes are its stethoscope, and in most readings its spin ran ahead for decades and now lags.
~24 min Simple · ~49 min FullRead
Two ways to read
Same ideas, same figures. Pick one and every post opens that way.
✨ Simple
The story
No background needed. Short paragraphs, emoji as signposts and almost no formulas, plus every interactive figure. Made for anyone who's curious.
∫ Full
The whole argument
The same ideas with the equations, numbered sources, error bars, and the caveats that didn't fit in the story.
About
Nugbrain is a small blog about the strangest true things in physics: ideas that are real, checkable, and a little mind-melting.
Every number comes with its source or its arithmetic, and anything that's a guess is labelled as one. If something here is wrong, it's a bug, and it gets fixed.