Experiment — not part of the product

Walk in the dark and be told

Following up a wounded animal at night means hours on bad ground in thick cover. Every thermal device sold puts a screen in front of your eye, so you lose your night vision and walk half-blind. We are testing the opposite: you never see a picture. A small thermal camera on your head, the phone in your pocket, and plain-looking display glasses. You walk in complete darkness. When something warm comes into view, a few dots light up in the corner of your eye, where it is. Turn until they are centred, and walk. A bigger animal lights more dots; close enough, it names the animal.

What it cannot do

• A narrow view. The camera sees about a quarter of what your eyes do. You sweep your head; you do not just glance around.
• No name at a distance. At 150 m it is a dot. It names the species only when the animal is close enough to be sure.
• Not cheaper. Camera and glasses together cost about what a head-mounted thermal does. The difference is that you keep both eyes and your night vision.

What we hope it can

• Tell you where something warm is, within a second of it coming into view, without ever showing you a picture.
• Show nothing at all when there is nothing there.

What we do not know yet

Whether the glasses can go dim enough for a pitch-dark wood, and whether a cue is really better than a picture after two hours on a hillside.