I’ve worked with a lot of research assistants over the years, and at some point we inevitably have The Talk: should they get a PhD? I was recently having The Talk with one particularly distraught student, who was worried her ideas aren’t good enough. “Maybe I’m not cut out for it,” she told me, “or maybe all of the easy ideas have already been done.”

Like her, I’ve worried that I was born too late and all the low-hanging fruit was picked before I got here. Fifty years ago, you could get a million citations just for showing that people like their own team the best, that kids will do something that they watch other people do, or that people think other people agree with them. Everything obvious has been done, and now it’s up to poor schmucks like me to figure out the hard stuff.