Pocket Universe



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Pocket Universe is provided for free download and use. If you like it, or have suggestions for future development, please use the feedback form.

About Pocket Universe

Pocket Universe, made in 1996, simulates the gravitational and thermodynamic interactions between particles, which closely models the behaviour of galaxies. On a typical desktop computer, simulations of 1000+ particles are modeled in real-time.

A universe of 2650 particles. After one minute: the first collision.

Mathematical models used in this program are representative only, are probably not realistic, and can not be deemed accurate for any purpose.

Calculation Model

An optional 'thermodynamic' processing model approximates thermal pressure and friction. This causes particles to readily cluster. In this case, pressure and friction have caused these perticles to settle into a rotating sphere. You might also notice a small fraction of the system mass circling in a ring.


Where pressure and mass are balanced, and kinetic energy is sufficiently low, a structure approximating a tetrahedral lattice will form.

When approximating large diffuse gas structures, friction should be set low. Likewise, when approximating denser objects, friction should be set high.

  • Friction: Slows down any particles that are travelling against each other in proximity, and converts the energy to heat.
  • Pressure: Depending on temperature and proximity, pressure will prevent particles becoming close to each other.
  • Luminance: The 'Show Luminance' option (View Properties), will show the emitted heat energy of the particles. A system can lose energy through friction then radiation. If a system becomes too dark to see, you can switch this option off, to view everthing at the same brightness.

Gallery of Screenshots

1. 8000 particles after a sticky first collision, on the default configuration.
2. After the next pass, barred-spiral distortions start. Particles near the core are hotter because of thermal friction, and some darker (non-illuminating) matter can be seen in front of the cores.
3. Further on, before the next collision, cores are brightening and the peripheries are dimming, so we've lowered the contrast to see the cooler material.
4. Later, and we've dimmed the contrast again to reveal more detail. There is more dark matter now.
5. The centre and bottom-right images are the same view, having only different contrast levels.
6. Eventually, they settle into a globular fuzz, via a disk-like structure, and burn out.


DateSubjectNews Item
25 Nov 2004Release 2.0

Further 'New Universe' options:

  • 'Colliding Galaxy' option.
  • Optimised 'local grid precision' processing brings great efficiencies to large universes.
  • Bond connectors, appearing when particles are within a defined proximity.
  • Further options to define initial state of clusters

02 Sep 1999Release 1.99
Alpha Stable

  • Multiple 3D first-person perspective views on the same 'universe', with pan, rotate, dolly and zoom.
  • Universe model that supports large simulations (2 million particles tested).
  • Views that display particles with luminosity and sub-pixel precision. This gives a characteristically 'optical' view, with smoother animation, precise positioning of particles, and better impression of density and depth.
  • Options for 4, 8, or 10-byte floating-point maths.
  • 32-bit Win95/98/NT4.

31 May 1996Release 1.00
Multiple orthogonal views onto a gravitational universe. 16-bit.