Heisenberg observes two crucial qualities: scale and potential. Relativity deals with cosmic scale and effectively infinite velocity. Newtonian physics agrees with it to the extent that it is remote from either. Likewise quantum mechanics deals with probabilities whose vanishingly small scale nonetheless chimes with Newtonian physics where probabilities begin to aggregate int definites. All that remained was to square the circle of the very large and the very small.
Hios second challenge is to reverse Aristotle by claiming potential, in the form of energy, as the founding quality of the universe: a tendency to become prior to and by no means destined for being as previously understood. We have lived so long on the balcony overlooking this abyss, framed by quantum and cosmic scales, that they have become second nature. And yet it is still hard to go beyond Newtonian/Cartesian duality, especially of subject and object.
Light is the privileged vehicle in which this cultural accomodation can be made.