Quantum lost soul
Quantum lost soul is a bug wherein lost souls may move at seemingly impossible speeds.
The bug is caused by the primitive three-dimensional nature of the Doom engine and similar discrepancies involving moving objects are not uncommon. A charging lost soul moves at a constant speed on the X and Y plane regardless of the Z coordinate difference between the lost soul's starting and target positions. This means that a lost soul which is relatively close to its target from a top-down perspective but having a high height difference will appear to charge much faster than would be expected. In exceptional cases with great height differences, the speed of the lost soul may give the impression that it violates the laws of physics.
Despite its appearance, this additional momentum does not increase the lost soul's charging damage.
The quantum lost soul bug is currently known to effect all versions and source ports of Doom.