In natural occurrences, a quantum singularity -- also known as a black hole -- is a star which has collapsed in on itself, with a powerful event horizon energy field around it. In 2371 the U.S.S. Voyager tried in vain to rescue a ship apparently trapped in one until it too was caught, finally exiting through the singularity's original rip in subspace by cutting its way out with a shuttlecraft's dekyon beam. In the first three hours of contact nine crewman reported symptoms of dizziness, muscle spasms, headaches; six hours later, 27 more had been affected. When detected, the opened rip had shrunk to a 50-by-10-meter hole. Romulans use a quantum singularity rather than a matter-antimatter reaction as the power source behind their warp drive; when cloaked it doesn't affect gravimetric field signatures as usual but does emit a low-level tetryons in the lower subspace bands as well as temporal displacement waves which can affect delta-series radio-isotopes. Chief O'Brien experienced a period of sensitivity from a dose of radiation poisoning, causing a temporal shift which assisted in the detection of a cloaked Warbird bent on destroying Deep Space Nine and the wormhole as an ultimate Dominion defense.