In short, you design experiments where classically you wouldn’t have electrons in a region. Then you measure a voltage where you shouldn’t (unless tunneling were possible).
In shorter: all matter is energy at a slow vibration. Insulation is just an impediment. This is why neutrinos flow through you right now. If you can vibrate at 2.4 ghz, you could walk through some walls.
In short, you design experiments where classically you wouldn’t have electrons in a region. Then you measure a voltage where you shouldn’t (unless tunneling were possible).
In shorter: all matter is energy at a slow vibration. Insulation is just an impediment. This is why neutrinos flow through you right now. If you can vibrate at 2.4 ghz, you could walk through some walls.