&quot;Any of the big companies -- Google, Facebook, and Amazon come to mind -- do tons of things that even 10 years ago would have been considered cutting-edge computer science research.&quot;<p>Absolutely true, but is it possible to work in those places without a PhD?<p>One path I can imagine would be to devote 2-3 years to independent study, attend appropriate conferences and get to know the researchers on a professional and personal level. Build some respect on your own dime before trying to move to professional work.<p>No idea if that would work, though - whether there are avenues for an amateur-but-devoted scientist to contribute to research, or whether that research would break down any barriers.