Airports may start using 'smart glass' to make you spend more

There are many depictions of a future in which we’ve mastered the art of manipulating the opacity of glass. Even in real life, sunglasses can adapt to the intensity of sunlight. So why, one might ask, can’t we have that in our homes, or at work?

The wait may soon be over. The tinted world of tomorrow is coming, and airports—mini-cities of steel, concrete and lots and lots of glass—are interested. In a test last fall, Dallas-Fort Worth International Airport outfitted one of its gates with a new type of “smart glass” that can adjust for sunlight exposure. The obvious point