But before that, Ernst Jentsch wrote about "the uncanny" in a 1906 essay, and Sigmund Freud followed up 13 years later.
CNN: Why zombies, robots, clowns freak us out
2.
"We have in the safe a lead lined container that contains some of the original radium that Madame Curie possessed, " says Jentsch.
NPR: Hidden Museum Treasures
3.
While discussions of cultural differences can spark debate, the Smithsonian's Eric Jentsch, a specialist in the NMAH's division of science, medicine and society, points to one object that's literally too hot to handle.