Light is all around us yet it has always been a mystery. As Einstein commented just before he died:
“All these fifty years of conscious brooding have brought me no nearer to the answer to the question ‘What are light quanta?’Nowadays every Tom, Dick and Harry thinks he knows it, but he is mistaken.” (Walker, 2000) p89
Nothing has changed today, as physics remains quite unable to say what light actually is.
QR3.1.1 The Mystery of Light
QR3.1.2 Particle or Wave?
QR3.1.3 Young’s Experiment
QR3.1.4 The Copenhagen Compromise
QR3.1.5 How Come The Quantum?