For centuries, most scientists have shared the belief that light behaves as both a wave and a particle. This idea, then, became the central component to quantum theory, sprouting the field of science known as quantum mechanics.
The double-slit experiment supported the idea, showing bright and dark bands that indicated wave-like interference. But now, a new study suggests that this experiment might not lock us into seeing light as a wave.
According to the experts, we can interpret those interference bands using quantum particles alone.
The research was led by Gerhard Rempe, the director of the Max Planck Institute for Quantum Optics. He teamed up with collaborators at Federal University of São Carlos and ETH Zurich for the study.
Modern physics and our view of light
In 1801, Thomas Young introduced an experiment by shining light through two narrow openings to produce intersecting fringes on a screen. His findings led many to conclude that light must be a wave.
A century later, quantum mechanics began to take shape, revealing that quantum particles like electrons could mimic wave-like light interference too.
Albert Einstein’s work on the photoelectric effect showed that light travels in discrete packets called photons. Niels Bohr then elaborated on wave-particle duality, ushering in one of the cornerstones of modern physics.
Dark and visible photons
The new approach from the research team explores the concept of bright and dark modes.
In their view, interference patterns can emerge from combining “detectable” and “undetectable” photon states. These bright states interact with an observer, while dark states remain hidden.
Such hidden photons might linger at places where we would normally think the light cancels out. Observers who try to track the path of these photons alter the state, flipping what was dark into bright or vice versa.
From this perspective, the light pathways can be viewed as quantum superpositions, rather than purely classical wave interference.
Hellbound and Down 