By examining Planck's equation E=hν, one finds an analogy with accounting billing forelectricity. Frequency and power have a physical dimension T-¹, so one obtains an energyvalue accounted for over a time interval by multiplying them by this time interval. Byinvestigating this analogy, one finds a surprising mistake in Planck's law for the frequency of black body radiation: confusion between two contexts, one for radiation power and one for a timeless energy density. One goes from one to the other by an accounting-typetransformation: A multiplication by 4π/c or c/4π. Correcting this mistake makes a Planckconstant h timeless, invalidating the photon definition and de Broglie’s wave-particle duality. Despite this mistake, one obtains the same value for the black body radiation; it goesunnoticed. Consequently, the Planck relation becomes P=hν, with the energy of a cycle equal to h, whatever the frequency. One can consider this cycle as a new photon, which behaves like aparticle by its radiation pressure. Its energy-mass equivalence h=mɣc² gives a mass of4.134883524·10-¹u2075 eV, in the range referenced by the Particle Data Group. This correction ofPlanck's relation calls quantum physics into question.