The Double-Slit Interference Experiment.
Its eeriness rivaled that of a horror movie, yet it was a serious scientific experiment.
Its purpose was to determine the fundamental nature of light.
At the time, one school of scientists believed that light consisted of particles—photons.
Another school believed that light was a wave, like the vibrations produced by beating a drum.
Thomas Young conducted a simple experiment.
He cut two parallel slits into a piece of cardboard.
Then he shone light through them.
If light consisted of particles, it would form a beam of particles. Like machine-gun bullets, countless photons would shoot out, pass straight through the slits, and cast two vertical streaks of light on the other side.
Whatever shape the slits had, that same shape should appear in the light spots. It was perfectly logical.
But that was not the result.
On the other side of the cardboard, stripes like a zebra crossing appeared—and there were far more than two.
An uproar followed.
Thomas Young reached a conclusion.
Light was a wave. When light waves passed through the slits, they formed crests and troughs, like advancing ocean waves.
Behind the two slits, the crests overlapped and became brighter, while the troughs dimmed into shadows. Their mutual interference created zebra-striped patches of light.
It was equivalent to dissecting light with the simplest possible method.
But the photon faction refused to concede.
Over the following years, the experiment underwent several "upgraded versions."
Pandora's Box had been opened.
And strange things began to happen!
A hundred years later, single-photon firing devices appeared.
Someone conducted another experiment, this time firing only one photon to see how it interfered!
The result was shocking.
A single photon actually formed an interference pattern?!
The photon faction gnashed their teeth, yet they could not explain it!
Another hundred years