Could a black hole really eat a planet?

If it passed close enough, yes — though a black hole with Earth's mass would be about the size of a marble, and a planet falling toward one would mostly be heated, shredded and flung away rather than swallowed whole.

What is a primordial black hole?

A black hole that may have formed in the first second after the Big Bang out of unusually dense regions, rather than from a collapsing star. None has been found; they remain a candidate for part of the dark matter.

What is the Big Crunch?

One possible end of the universe: with enough matter, gravity would stop the expansion and pull everything back together. Measurements of dark energy make it unlikely for our universe, which is expected to expand forever.

Why do small black holes evaporate?

Stephen Hawking showed in 1974 that black holes should emit radiation because of quantum effects near the horizon. The smaller the hole, the hotter it glows and the faster it shrinks; a black hole with the mass of a star would take vastly longer than the age of the universe.

How much is in the observable universe?

It is about 93 billion light years across and holds roughly 10⁵³ kilograms of ordinary matter, in hundreds of billions of galaxies. That ordinary matter is the game's winning mass; dark matter would add about five times as much again.

Do I need an account, or to download anything?

No. It runs in the browser, keeps your records and your catalogue on this device only, and its sound is synthesised as you play — there are no audio files.

Big Crunch — a black hole game where you eat the universe

A game about gravity winning

BigCrunch

You are a black hole with the mass of a mountain. Swallow anything smaller than you, grow through forty orders of magnitude, and eat the universe before its last star goes out.

Mouse to steer · click or Space for jets · P to pause · M for sound

A game about gravity, honest about where it cheats

Big Crunch starts you as a primordial black hole of 5×10¹¹ kilograms — a mountain's mass inside a radius smaller than a proton — and ends, if you are good, when you have swallowed about 1.5×10⁵³ kilograms: every atom of ordinary matter in the observable universe. In between you climb nine tiers, from rubble to the cosmic web, and what you meet on each follows the real mass of whatever you have grown into.

The game keeps a catalogue of 54 real objects, from the asteroid NASA deliberately knocked off course to the heaviest black holes known, each with its measured mass and one line on why it is worth knowing. Some of the game is physics and some of it is game. This page says which is which.

What is real

The starting mass. 5×10¹¹ kg is about the mass at which a black hole's Hawking lifetime equals the age of the universe. If primordial black holes formed in the Big Bang, the ones this size would be finishing their evaporation now.
The catalogue. Every object's mass is the published value, or the conventionally quoted middle where estimates range — anything with a dark-matter halo has a range. The tiers are real boundaries too: bodies pull themselves into spheres around 10²⁰ kg, and hydrogen fusion needs about 0.08 Suns.
Small black holes evaporate. Hawking radiation makes a black hole lose mass, and the rate climbs steeply as the hole gets smaller. The game keeps that shape — only the smallest holes feel it — but speeds it up enormously, so the start of every run has a clock on it.
Stars unspool as they fall in. A star that strays too close is stretched by the difference in gravity across it and drawn out into a stream. Astronomers have seen about a hundred of these tidal disruption events, each a flare from the centre of a galaxy.
Jets. Feeding black holes launch twin jets of plasma at nearly the speed of light, in opposite directions — which is why the game's jets always come in pairs and cancel each other's recoil.
The merger chirp. When two black holes merge, the gravitational waves rise in pitch and strength until the moment they become one: the chirp LIGO heard in 2015. Catching a rival plays it.
Dark matter, seen by what it bends. The invisible clumps you can find in the later tiers are drawn only as a distortion of the starlight behind them. That is how dark matter is actually mapped — by gravitational lensing, as in the Bullet Cluster.
The cosmic clock. A run covers the universe from the first galaxies to the end of the age of stars, about 10¹⁴ years from now, when the last red dwarfs burn out. It runs on a log scale, because nothing about cosmic history is evenly spaced.

What the game bends

Your size is your reach, not your horizon. Everything is drawn with a size in proportion to the cube root of its mass, so a planet and a galaxy can share a screen. A real event horizon grows in proportion to mass and is absurdly small: Earth's would be about the size of a marble.
Real black holes are messy eaters. Matter falling in heats up and shines, and much of it is blown away rather than swallowed. The game credits you with every kilogram you touch.
Most of your rivals are made up. No known black hole is heavier than about 10¹¹ Suns. From the galaxy tier up, the ones chasing you are as fictional as you are.
The real Big Crunch is not a black hole. It is the whole of space falling back in on itself, which happens in the Tuner when the density dial Ω is set well above one. This is the version where it is your fault.
Nothing here moves at the right speed. A universe lasts nine minutes, a comet crosses the screen in a second and a galaxy turns while you watch. Time is compressed by different amounts at every scale, so the game stays playable at all of them.

Play any universe

Every universe the Tuner makes can be played. The nine dials become the game's physics: stronger gravity lengthens every black hole's reach, a denser universe has more to eat, lumpiness packs it into tighter clumps, dark energy drags distant matter away late in the run, more dark matter hides more of the food, and hotter nuclear physics makes stars explode more often. Open any universe in the Tuner and add ?u= with its code to this page's address.

There is also a universe of the day — one or two dials moved well away from ours, the same for everyone — so runs can be compared. In the Tuner most of these universes die long before there would be anything to eat; the game clamps every setting to something playable, and the result screen says how the Tuner thinks that universe really ends.

Big Crunch is a game, not a model. Its masses and its catalogue are real; its speeds, reach and rivals are tuned for play. Nothing in it is evidence for any answer to why the universe is the way it is.

Questions

Could a black hole really eat a planet?: If it passed close enough, yes — though a black hole with Earth's mass would be about the size of a marble, and a planet falling toward one would mostly be heated, shredded and flung away rather than swallowed whole.
What is a primordial black hole?: A black hole that may have formed in the first second after the Big Bang out of unusually dense regions, rather than from a collapsing star. None has been found; they remain a candidate for part of the dark matter.
What is the Big Crunch?: One possible end of the universe: with enough matter, gravity would stop the expansion and pull everything back together. Measurements of dark energy make it unlikely for our universe, which is expected to expand forever.
Why do small black holes evaporate?: Stephen Hawking showed in 1974 that black holes should emit radiation because of quantum effects near the horizon. The smaller the hole, the hotter it glows and the faster it shrinks; a black hole with the mass of a star would take vastly longer than the age of the universe.
How much is in the observable universe?: It is about 93 billion light years across and holds roughly 10⁵³ kilograms of ordinary matter, in hundreds of billions of galaxies. That ordinary matter is the game's winning mass; dark matter would add about five times as much again.
Do I need an account, or to download anything?: No. It runs in the browser, keeps your records and your catalogue on this device only, and its sound is synthesised as you play — there are no audio files.