Paintings and Conversations

“The classic example of the superposition of possibilities and the observer effect is the famous double-split experiment.  In this experiment, a stream of subatomic particles is directed through the screen containing two very closely spaced slits.   It allows particles to pass only one by one through the slits.  Each particle makes its way to a second screen, where it hits and makes a single tiny spot.  yet after many particles have made their way through, a pattern of dots appears on the second screen that can only be explained if each particle passed through BOTH slits simultaneously.  In other words, the two possibilities – one slit or the other – seem to superimpose to produce a new result.

Amazingly, if you close one of the slits, more particles reach certain places on the screen than if you left both slits open.  With both open, each particle aparently has two choices of which slit to pass through, so each should have twice an opportunity of reaching any point on the screen.   In other words, any point on the screen should be twice as likely to record a hit, so there should be fewer open spaces between spots when both slits are open.  But the opposite is true.

What is an explanation for this bizarre behavior?  It seems that the two opportunities somehow affect one another: they interfere or bump into each other . How can it be?  No particle ever encounters the slits in the presence of another particle.    Can quantum physics explain it ?  Yes.  Suppose that instead of a single particle passing through , what passes is a wave. A wave does not behave like particle.  It would reach both slits at the same time and than brake into two waves, one passing through each slit.

This behavior is called wave-particle duality. The notion that the same entity can be both a particle and a wave opens up to us a new view of the world.  ”

Fred Alan Wolf