Live Science article

Quantum Particles Take the Road Most Traveled

By Kelly Dickerson, Staff Writer | August 06, 2014 10:59am ET

For the first time ever, physicists have mapped the path that particles are most likely to take when moving from one quantum state to another.

In physics, a concept called the "path of least action" describes the trajectory that an object is most likely to follow, similar to the familiar concept of the "path of least resistance." For example, a tossed football follows a parabolic arc through the air instead of spinning off in crazy loops or zigzags. That's because a parabola path requires fewer "actions" than a looped or zigzag path.

However, physicists didn't know whether quantum particles, like electrons, neutrinos or photons, follow the same rule. Many of the classic rules of physics don't seem to apply to these tiny particles. Instead, they are governed by the weird rules of quantum mechanics that even Einstein called "spooky."

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