In Star Trek, a spatial implosion is a type of spatial anomaly where space-time is compressed, crushing any objects occupying it. A distortion ring that enveloped the USS Voyager in 2371 also seemed to act as a spatial implosion, that eventually would crush the ship. It later emerged that this was not the case, as the ring was in fact a lifeform that released Voyager unharmed. (VOY: "Twisted").

In real physics, the term implosion is a process in which objects are destroyed by collapsing on themselves. The opposite of explosion, implosion concentrates matter and energy. Implosion is a key part of the gravitational collapse of large stars, which can lead to the creation of supernovae, neutron stars and black holes.

Gravitational collapse in astronomy is the inward fall of a massive body under the influence of the force of gravity. It occurs when all other forces fail to supply a sufficiently high pressure to counterbalance gravity and keep the massive body in hydrostatic equilibrium.

Gravitational collapse is at the heart of structure formation in the universe. An initial smooth distribution of matter will eventually collapse and cause the hierarchy of structures, such as clusters of galaxies, stellar groups, stars and planets. For example, a star is born through the gradual gravitational collapse of a cloud of interstellar matter. The compression caused by the collapse raises the temperature until nuclear fuel ignites in the center of the star and the collapse comes to a halt. The thermal pressure gradient (leading to expansion) compensates the gravity (leading to compression) and a star is in dynamical equilibrium between these two forces.

Gravitational collapse of a star occurs at the end of its life time, also called the death of the star. When all stellar energy sources are exhausted, the star will undergo a gravitational collapse. In this sense a star is in a "temporary" equilibrium state between a gravitational collapse at stellar birth and a further gravitational collapse at stellar death. The end states are called compact stars.

Even more massive stars, above the Tolman-Oppenheimer-Volkoff limit cannot find a new dynamical equilibrium with any known force opposing gravity. Hence, the collapse continues with nothing to stop it. Once it collapses to within its Schwarzschild Radius, not even light can escape from the star, and hence it becomes a black hole. At some point later the collapsing object must reach the planck density (as there is nothing that can stop it), where the known laws of gravity cease to be valid. There are competing theories as to what occurs at this point, but it can no longer really be considered gravitational collapse at that stage.