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Equation 1 · Part 4 · The Photon Counters in Your Retina — Evolution at Einstein's Limit

=

E=hνE = h\nu
=

What this part means

The expressions on both sides represent the same quantity under the stated assumptions.

Its job in the formula

The equals sign connects the complete expression on the left with the complete expression on the right. Both sides must have compatible units.

The passage around this formula

Albert Einstein’s paper “On a Heuristic Point of View Concerning the Production and Transformation of Light” reached the editors of Annalen der Physik on 18 March 1905 and was published that June, one of four papers from what is now called his annus mirabilis [ 1 ] . Its actual claim is narrower than the “light is made of particles” shorthand it gets today. Einstein proposed, as a heuristic — his own word, chosen because he was not yet willing to overturn the wave theory that already explained diffraction and interference — that “the energy of a light wave emitted from a point source is not spread continuously over ever larger volumes, but consists of a finite number of energy quanta that…

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Learn the underlying idea

An equals sign says that the expression on its left and the expression on its right have the same value under the stated definitions and assumptions.

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Sources cited in the surrounding passage

These citations provide research context; check each source for the exact claim it supports.