“You are not simply an electrician, you are illuminating the world!” claims one of the six characters in “The Light Years,” a pleasant, but less than fulfilling concoction now playing at Playwrights Horizons. Produced by a company called the Debate Society – which recreates slices of Americana – it focuses on two Chicago world fairs, exactly forty years apart. It is also about invention, creativity, failure and loss.

Obviously, the four decades between 1893 and 1933 were huge ones, especially when one thinks of how technology evolved. Who knew that in the first of Chicago’s fairs, a charismatic man was dreaming up something called the Spectatorium, a brightly beaming theatre to seat some 12,000 visitors? Alas, it never came to be.

This intermission-free six-actor piece time travels – though two characters span both the mega events – and the sets, costumes and props accordingly change before our eyes. There are deaths, explosions emitting from dreamy contraptions, actors roaming among the audience, and dialogue that certainly tickles the audience, if not my particular funny bone.

The actors are all very good, particularly the sprightly and witty Aya Cash, who plays two women of the dual periods, and Rocco Sisto, who plays the actual figure with the great name of Steele MacKaye. The visionary behind the Spectatorium folly, MacKaye is little remembered at all today. He wrote, he directed, he dreamed big, and by the way, he invented folding theatre seats and the free playbill.

“The Light Years” was co-written by Hannah Bos and Paul Thureen, who admit they have always been fascinated with World Fairs: those odd entities that build big, show millions of visitors what the future may hold, and then generally tear it all down. This production gives us a taste of that, though it is far less gripping than the hugely popular book “Devil in The White City.” But it is certainly recommended for a family’s night out. There is a bright and curious child, flashing bulbs of all sizes and shapes, constellations sparkling from above, and even some history that goes down easily.