Quantum Behavior: Feynman's Physics Explained
Here is the heart of modern physics, and it is a true mystery. Send electrons through two slits and they arrive one by one, like particles — yet the pattern they build up is an interference pattern, as if each electron were a wave passing through both slits at once. Try to watch which slit an electron takes and the interference vanishes. The very act of observing changes the outcome. This is the central puzzle of quantum mechanics.
The big idea
A single particle can interfere with itself — until you look.
Think about it
Why is it so unsettling that simply observing which slit an electron goes through changes the result?
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