T'ronna Equations was a set of scientific equations setting forth a series of unchanging physical constants that formed the basis of Vulcan astrophysical science. Its third equation was similar for all intends and purposes as Human Hubble Constant or Denobulan's Parnikee's Theorem.
After its creation in Vulcan history, it stood alongside other scientific theories such as S'ral's Theorem and the Shi'Kahr Principles. In 2153, T'Pol explained T'ronna Equations to Earth Starfleet Captain Jonathan Archer where Doctor Phlox commented that it was similar to Parnikee's Theorem. (ENT novel: Daedalus's Children)