Modern physics was founded upon exploration of light. Albert Einstein’s 1905 breakthrough in physics – relativity theory – came in considering the nature of light. Light excites matter enough to liberate electrons, a phenomenon known as the photoelectric effect.
Einstein’s attempt to suss the photoelectric effect ended in explaining some fundamentals of existence: what was reliably constant (only the limit of light’s quickness) and what was not (everything, including space and time). Einstein’s assumption that light speed was the limit of existence owed to Scottish physicist James Clerk Maxwell, who found in 1861 that “force fields” (electromagnetic waves) danced at the speed of light.
Following Dutch physicist Christiaan Huygens’ 1678 proposal, English physician Thomas Young demonstrated in 1803 that light behaves as waves, like ripples in water. Young’s experiment disabused Isaac Newton’s 1672 insistence that light was “corpuscular”.
In 1900, trying to figure out how to get the most light out of light bulbs, German physicist Max Planck mathematically took energy to its physical limit, and found that energy invariably exists in quantized form.
Einstein, by way of Planck, fell into Newton’s camp. While light may appear as coherent, entangled waves, it simultaneously acts as if it is composed of entangled quanta: photons.
Quantization is Nature’s great trick. Existence incessantly emerges from an immaterial unity by creating particles of energy waves, neatly laid out in patterns which we perceive as actuality, and easily confuse as reality. Confusing actuality with reality is known as naïve realism.