From a CityLab.com online article:
The first of these urban amenities arose in the 1960s, but it was in the 1980s and ‘90s that the construction of science centers truly boomed. Inspired by historic World’s Fair exhibitions, industrial and natural history museums, and the sci-fi dreams of their early founders, science centers had a hands-on mission distinct from that of most museums—to engage rather than display. They offered levers you could pull, gyroscopes you could spin, lab experiments you could conduct.
The science center is an adolescent among museum types, one whose main growth spurt was in recent memory. Over the past 40 years, they went from a sparse to a ubiquitous presence, now found in almost every major city. Their emergence stretched the ontological essence of the museum: They present not objects, but concepts. Many science centers define themselves explicitly this way and possess slim to no permanent collections.