[AntonioLao]

The search of time invariance started since Emmy Noether (1882-1935) formulated her symmetry and conservation theorem. Parity invariance was broken in the 1950s and CP invariance was broken there after. Charge invariance was broken since it was determined that an atom is composed of a massive positive electrically charged nucleus surrounded by almost massless negatively charged electrons. One on one, the proton and electron has identical absolute magnitude of electric charge. Advanced physics like the Standard Model was able to describe these broken symmetries C, P, and CP by electroweak field with massive weak charges of intermediate vector bosons. However, the electroweak concept failed to describe the strong color forces of massive quarks and massless gluons. Nevertheless, the color invariance can be broken by the discovery of the massive Higgs scalar boson and together with the discovery of graviton would be more than enough to seal the acceptance for both QCD and quantum gravity into mainstream physics.

The conceptual existence of positive and negative time axes could possibly give a more satisfactory explanation for all these broken symmetries stating that time itself is not invariant at the fundamental level. This broken time symmetry asserts that the vector sum of positive and negative time axes can never be identically zero. The sum is always positive definite implying the existence of a metric for time axis comparable to Planck length.