What does "we owe our careers to having been the scientists"? Does it mean "We have our careers because we have become the scientists (who had the careers)"? It is not understandable to me. The problem seems to lie in two places: (1) Does "having been" mean "having become"? (2)Does "who had them" mean "who had the careers"?
I suspect it’s hard for many physicists to imagine that we are not near the end of our search for the ultimate laws of nature. We have been raised in a culture in which it’s all about having the right answer, and we owe our careers to having been the scientists who had them. But I’ve always had in my head an image of how much more people in the future will know, and how silly our claims to knowledge will look to them. This has probably made me a less effective advocate of my own ideas.