Alexander Friedmann

July 2026

Who he was

Alexander Friedmann (1888–1925) was a Russian physicist and mathematician. In 1922, he derived the equations describing how the universe expands or contracts over time directly from Einstein’s general relativity — before Hubble’s 1929 observations confirmed the universe actually is expanding, and before Einstein himself accepted the possibility (he initially added a “cosmological constant” specifically to avoid it).

What he’s known for on this site

The Friedmann Equation ($H^2=(8\pi G/3)\rho_{eff}+\Lambda c^2/3$) is the real, foundational equation of modern cosmology, relating the universe’s expansion rate to its energy density. Paper 9 uses this exact equation as the framework for PBT’s own cosmological claims.

Catalog status: Proven Systems

The Friedmann equation’s expansion/thermal-history framework is proven to high precision (Hubble expansion, the CMB, Big Bang nucleosynthesis) — see Standard Cosmology for the split between what’s proven and what (dark matter, dark energy’s literal nature) remains genuinely open.

Mentioned on this site

• Friedmann Equation
• Standard Cosmology
• Paper 9 and Paper 12

Where this touches PBT

PBT’s own cosmology plugs its aether-medium energy density directly into Friedmann’s real, unmodified equation — the equation itself isn’t PBT’s claim; what’s unproven is specifically PBT’s own value for $\rho_{eff}$.