Planck energy
| Value | 1,956,081,637 J |
| Status | Measured: ± 22,000 J (0.000011 relative) |
| Source | CODATA 2022 (derived from ħ, c and G; uncertainty inherited from G) |
| Categories | Universal & Atomicphysicsquantum |
| joule | 1,956,081,600 J |
| kilojoule | 1,956,081.6 kJ |
| megajoule | 1,956.0816 MJ |
| calorie | 467,514,730 cal |
| kilocalorie | 467,514.73 kcal |
| watt-hour | 543,356.01 Wh |
| kilowatt-hour | 543.35601 kWh |
| British thermal unit | 1,854,007.7 BTU |
| foot-pound | 1,442,731,800 ft⋅lb |
| electron volt | 1.2208901e+28 eV |
| kiloelectron volt | 1.2208901e+25 keV |
| megaelectron volt | 1.2208901e+22 MeV |
Learning zone
Two ways of reading the same number make the Planck scale vivid. In particle terms it is 1.22 × 10¹⁹ GeV, a quadrillion times the LHC's 13.6 TeV, unreachable by any accelerator that fits in a solar system. In everyday terms it is 1.96 gigajoules — the kinetic energy of a 1.4-tonne car at about 190 km/h, or roughly half a tonne of TNT. The difference is that the Planck energy is concentrated on a single particle.
This is where the four forces are conjectured to unify and where a graviton exchange becomes as strong as a photon exchange. Nature does get close: the highest-energy cosmic ray ever recorded, the 1991 "Oh-My-God" particle, carried 3 × 10²⁰ eV — a single proton with the energy of a well-struck baseball, yet still eight orders of magnitude below E_P. Some quantum-gravity models predict tiny energy-dependent delays in gamma-ray bursts suppressed by E_P; none has been seen.