It's the bulk mail method. Send physics at two million people a year, not everyone is going to "get" it. But we don't know which of those two million are going to grow up and revolutionize the semiconductor industry, which of those are going to jury-rig some clever device at home that keeps their energy bill down, and which of them are going to forget it all.

Just like you never know which email address will respond to a Viagra advertisement.