Spiral Energy is the primary power source of all Spiral beings and primary theme of Tengen Toppa Gurren-Lagann.
Not only is it the basis of strength for the main characters and all of mankind, but it is presented as a philosophy and a model of physics.
Description and Meaning
In the series' concept, Spiral Energy is the power of evolution, generated by beings capable of doing so, like humans and other DNA-based animals, whose spiral double helix molecular structure allows them to get stronger through the generations. Spiral energy is what connects spiral beings to the universe. Beastmen, because they do not reproduce naturally, cannot evolve, thus are unable to produce Spiral Energy. The amount of Spiral Energy produced by an individual may vary and is based not only on its own limitations, but also its immediate will to survive and persevere.
Spiral Energy has both infinite potential and applications - it has been known to regenerate and grow new parts on machines to a galactic scale, and even create tunnels through spacetime. One of its most prevalent applications in the series is in weaponry: Spiral-enhanced ammunition provides phenomenal stopping power, making a simple shotgun capable of damaging a Mugann, while Spiral-based warheads and energy beams demonstrate destructive power far in excess of nuclear weapons. Another hypothetical application mentioned by Gimmy in the final episode is the power to resurrect the dead, the only possible proof being when Kamina reappeared to break Simon and Yoko free of their dream-mazes. However, Simon and Leeron rejected the idea, seeing it as a hindrance to the future.
Lordgenome, whose own name contains the word genome, referring to DNA and its spiraling double helix, notes that it is the natural order of the universe to coordinate itself into a spiral arrangement. The spiral symbolizes the double helix structure of DNA, representing biological evolution, and the spiral structure of a galaxy, representing universal evolution. Simon's spiral drill is used as a motif to symbolize the spiral theme throughout the series. At the same time, the drill motif symbolizes the strength to challenge or 'drill' through tough obstacles.
In the same way a logarithmic spiral grows in size with each successive curve, the scope of Gurren Lagann's story and the scale of its mecha grow in successive steps as the series progresses. By the end of the series, the largest mecha, the Tengen Toppa Gurren-Lagann, contains all the smaller iterations of Gurren-Lagann nested inside like a matryoshka doll, reflecting the way the curves of a spiral grow in size but maintain the same shape.
Every character is capable of utilizing their spiral energy in some way, however there are only a few known characters that have fully unleashed or awakened their spiral powers in the story line: Kamina, Simon, Kittan, Boota, Lord Genome, and the collective consciousness of the Anti-Spirals.
Spiral Energy is specifically stated to defy conservation of energy, which in addition to explaining the creation of mass that is practically constant during battles, also carries danger if Spiral Energy is overused.
Eons before the story begins, a certain race evolved enough to prosper across the stars through the use of their Spiral Energy. However, discovering that the limitless evolution and power could one day lead to the destruction of the entire universe, an event they termed the "Spiral Nemesis", they abandoned the use of Spiral Energy and sealed their bodies on their home planet, ceasing to evolve, and calling themselves the Anti-Spirals.
As the name implies, they also acted to repress other civilizations that used Spiral Energy, fearing that they could also become a threat to the universe if left unchecked. Since Spiral Energy comes from the will of its users, the Anti-Spirals tend to employ tactics specifically designed to induce fear, despair and hopelessness in their enemies. The Anti-Spirals also tend to spare their enemies if they surrender, but leave behind automated "defense" systems that will activate and attack a Spiral civilization if it grows too strong.
Since Spiral Energy comes from willpower, it can be assumed that the equivalent creation was their embodied consciousness, the Anti-Spiral, who is the one that actively leads their army.