The spectrum of radiation visible to humans maxes out around 740nm, allowing the IR ... lights are not visible to humans, they don’t obstruct normal behavior, making it an ideal way to hide ...

We’ll take a look at the underlying concept behind such devices below ... with varying wavelengths of light, and through some very advanced physics, hide objects from view.

There are more supermassive black holes than previously thought, say scientists (Alamy/PA) Many more supermassive black holes could be hiding in ... re-emits this light as infrared radiation ...