Ever wonder how night vision goggles work? Most work by detecting and amplifying infrared light. We can't see infrared light but it's there. Trees and buildings give off low levels of infrared light. Humans and animals emit more.
Night vision goggles collect these photons or energy packs of light that are invisible to us and convert their light energy into electrons. Then the goggles multiply the amount of electrons and finally present the enhanced amount of electrons to a phosphor screen which produces a bright picture of the otherwise dim scene with images that we would have never seen on our own.
That's basically how it works anyway. The science of night vision goggles allowing us to see things our eyes can't. Things hidden in plain sight.