Spiral Nemesis

The Spiral Nemesis (スパイラル・ネメシス, Supairaru Nemeshisu?) is a hypothetical event which the Anti-Spiral race are fighting to prevent. It would theoretically occur when Spiral Energy evolves beyond a certain point. As the Anti-Spiral themselves explain it, the crux of the matter is Spiral Energy's ability to defy the laws of physics, already shown throughout the series (IE: creating matter from nothing, from Giga Drill Breaks to the transformation of the higher levels of Gunmen). If enough Spiral Energy was generated, all life forms in the universe would begin spontaneously evolving into full-sized galaxies. The sudden imbalance of mass in the universe would lead to these mega-galaxies devouring each other, forming a black hole which would consume the universe. The Anti-Spiral's actions throughout the series are intended to limit the amount of Spiral Energy in the universe, thereby reducing the risk of Spiral Nemesis occuring.

Of course, in The Lights in the Sky are Stars, it is shown that the Spiral Nemesis is more than theory. When Super Tengen Toppa Gurren Lagann and Super Granzeboma's Giga Drill Breaks collide, the entire Anti-Spiral universe begins to collapse into itself. Of course, this was on an order of magnitude far greater than even the Anti-Spiral thought the Spiral races were capable of. The Spiral Nemesis, while possible, requires a great deal more mass and Spiral Power than the Anti-Spiral had initially surmised.

Debate (WARNING: OUT-OF-UNIVERSE SPECULATION BELOW)
The nature and likelihood of the Spiral Nemesis is one of the biggest lingering questions in Tengen Toppa Gurren Lagann. Team Dai-Gurren appears to believe the Anti-Spiral's theory, resolving to either prevent or somehow defeat the event if it ever becomes a problem, but whether or not the Spiral Nemesis is a real danger to the universe is never really answered.

Among the fandom, several theories about the Spiral Nemesis have been proposed. The most common positions are as follows: Each of these theories - as well as others - have their believers and detractors, but the true nature of the Spiral Nemesis is (and likely always will be) a mystery.
 * The Spiral Nemesis is a real threat, but if Spiral Energy is not overused, it can be prevented.
 * The Spiral Nemesis is an inevitable consequence of evolution; when the universe's life forms grow too advanced, their combined Spiral Energy will destroy everything. Limiting Spiral Energy delays it, but there is no way to actively prevent the Spiral Nemesis from occuring.
 * The Spiral Nemesis is part of a universal life cycle; after everything has been devoured by the supermassive black hole, a new Big Bang will occur, beginning creation anew.
 * The Spiral Nemesis is only an Anti-Spiral theory, but the Anti-Spirals took no chances and acted as though it would occur.
 * The Spiral Nemesis is merely the Anti-Spiral's own justification for the extermination of Spiral Energy.
 * The Spiral Nemesis is an Anti-Spiral theory, but also happens to be a real phenomenon.
 * The Spiral Nemesis is a living entity that feeds on Spiral Energy, growing more powerful as it does so.