alt Hacker NewsI think this is a gross cultural misconception. Most scientists do their best work in their 30s and 40s. See [0].
My take on this is that it takes about a decade before experience, knowledge and wisdom can be used to see a bigger picture to make a breakthrough.
[0] https://priceonomics.com/at-what-age-does-genius-strike/
A useful link but note:
a) the curve indicates 30s not 40s
b) there is no breakdown into theoretical vs experimental research, or scientific field; theory I would expect to be over-represented at the younger end especially as the science discipline becomes "harder".
Overall I would say it lends credence to the idea physics is a young person's game at the very highest levels.