Tell them that it was a mistake for Google not to put a red light indicating that a photo or video is being taken, and that you hope there will be one in future iterations (even though evil folk may find a way to somehow disable the light).

WSJ: Google Glass: An Etiquette Guide

It's palm-sized with a single blue LED light indicating a connection, but honestly you don't ever need to look at it: it doesn't need line-of-sight to your handset because it uses a wireless protocol called WiFi Display, which means you can happily leave it dangling out of the way behind your TV.

ENGADGET: AllShare Cast wireless streaming dongle for Samsung Galaxy S III -- hands-on (video)

Her pupils were dilated and did not react to light, indicating that her brain was no longer working.

NEWYORKER: The Checklist

We recently reduced our market growth estimates for notebook shipments, in light of evidence indicating tablets cannibalizing notebook sales.

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But they were shocked to see a vast swathe of ultraviolet light from young stars, indicating that the galaxy is actually big enough to accommodate five of our Milky Way galaxies within it.

BBC: Galaxy crash sparks biggest spiral

More modern versions of the tool add in a laser beam projector, which allows builders to level out the device and "draw" a long line of light across a wall, indicating an exactly level surface.

FORBES: No. 18 The Level

After what felt like an eternity waiting, the little red light on the camera flickered, indicating that the image was ready to view.

BBC: Meet July��s BBC Travel Photo Nomad