2.3  Program operation

For simulation, the objects whose motion you want to model shall be defined.

2.3.1  Objects

Gravity is a program to model the gravitational motion of Bodies. The bodies may belong to Groups handled as a single unit. The bodies all together form the System.

Let’s have e.g. four bodies: Sun, Venus, Earth and Moon and let’s have e.g. two groups: Sun system and Earth system, and the name of the system: Solar system. All bodies belong to the Sun system, but the Earth and the Moon are belongs to the Earth system too:

Only one system may exist simultaneously, as there is one universe¹ and each body acts on each other body². The number of groups is 16, but there may be groups, to which none of the bodies belongs to. The number of bodies is not limited, it is depending only the computer resources. Any one body belongs to many groups.

1 This is also suggested from its name. There are theories, by which multiple universes may exist (multiverse), but no connection exists between such universes, neither does gravity drive.

2 In Newton’s mechanics.