Quantum Fluctuations Were Experimentally Proven Way Back In 1947
“The issue is that the atom itself is always present, and it exerts an electromagnetic force: the Coulomb force, for electrostatic attraction. The quantum fluctuations in the field cause electron fluctuations in its position, and that causes the average Coulomb force to be slightly different from what it would be without these quantum fluctuations. Because the geometry of the 2S and 2P orbitals are slightly different from one another, those quantum fluctuations — which show up as virtual photons from the charged particles in the atom — affect the orbitals differently, resulting in the Lamb shift.
There are differences between the shift of a bound electron and a free electron, but even free electrons interact with the quantum vacuum. No matter where you go, you cannot escape the quantum nature of the Universe. Today, the hydrogen atom is one of the most stringent testing grounds for the rules of quantum physics, giving us a measurement of the fine structure constant — α — to better than 1-part-in-1,000,000. The quantum nature of the Universe extends not only to particles, but to fields as well. It isn’t just theory; our experiments have demonstrated it for more than 70 years.”
Have you ever thought about virtual particles, and then dismissed them as “not even real?” It would make sense if you did: we can’t interact with them, scatter real particles off of them, or get them to show up in our experimental detectors. But their effects are very real, and we detected those effects way back in 1947: before we even had working, accurate quantum field theories.
Here’s how we learned about them, and you might come away with a new appreciation for a brilliant experiment that never gets its due: the experiment behind the Lamb shift.