How does Replaceability applies to overcrowded academic areas that have an oversupply of PhDs slaving away in postdocs never to find a permanent job? This glut of PhDs must mean the actual impact of me joining a field like Particle Physics would be very low. Is that correct?
How is that different to one of the recommended career paths by 80000 Hours, Biomedical Research, which is also competitive, but is marked as high impact?
For context, I must mention that Biomedical Research seem to tackle more 'solvable' problems while Theoretical Physics has been mostly stagnated since the standard model (little progress has been made in several decades). For example, a few scientists predicted the Higgs boson within a short time of each other, Higgs was merely the first to do so. It should also be added that Biomedical Research positions exist in Big Pharma, while Theoretical Physics is limited to academia.
I have read many articles about replaceability. In special, the 80000 Hours 3-part series "How many lives does a doctor save?" about the impact of new doctors, as well as the Rational Altruist blog on Replaceability (https://rationalaltruist.com/2013/01/22/replaceability/). But I still have this question.
I believe the answer may be in the post "What does economics tell us about replaceability?" (https://80000hours.org/2014/07/what-does-economics-tell-us-about-replaceability/) but I am no economist and most of it flew over my head. I guess I need someone to dumb it down a little for me.