Energy

Energy is required to move or heat an object. The laws of physics state that matter cannot be created or destroyed and only converted between mass and energy (e=mc2). Living organisms require energy to live, move, function and stay alive.

These are non-renewable or natural resources that cannot be readily replaced by natural means at a pace quick enough to keep up with consumption.

Renewable energy is collected from renewable resources, which are naturally replenished on a human timescale.

See also:


 * Propulsion methods for spacecraft.
 * Faster-than-light engines for spaceships.