Einstein’s discovery that a photon has a finite quantum of energy proportional to its discrete frequency, and the representation of that photon as a wave packet, gives me a problem. E = h ν The photon packet waveform surely must have a beginning and an end? It is probably continuous, etc.? The transform of such a packet waveform, whatever its precise shape, must contain many frequencies in order to “localize” the photon between its beginning and end. So what is the frequency in Einstein’s quantum expression? Any thoughts are appreciated.