The reality of quantum fluctuations was proven back in 1947 | by Ethan Siegel | Starts With A Bang! | Aug, 2024

Often viewed as a purely theoretical, calculational tool only, direct observation of the Lamb Shift proved their very real existence.

If you spend enough time listening to theoretical physicists, it starts to sound like there are two separate worlds that they inhabit.

1. The real, experimental-and-observational world, full of quantities and properties we can measure to high precision with a sufficient setup.
2. The theoretical world that underlies it, full of esoteric calculational tools that model reality, but can only describe it in mathematical, rather than purely physical, terms.

One of the most glaring examples of this is the idea of virtual particles. In theory, there are both the real particles that exist and can be measured in our experiments, and also the virtual particles that exist throughout all of space, including empty space (devoid of matter) and occupied (matter-containing) space. The virtual ones do not appear in our detectors, don’t collide with real particles, and cannot be directly seen. As theorists, we often caution against taking the analogy of virtual particles too seriously, noting that they’re just an effective calculational tool, and that there are no actual…