A friend of mine's son started doing Multidisciplinary Science at University this year at the age of 14, which means he'll have his first degree by age 16 (he's currently getting High Distinctions in everything - that's a GPA of 7), so willprobably have a PhD in Physics by 19 or 20 at this rate.
So, yes, it's possible, but presents all sorts of headaches for the Universities with regards to duty of care of minors.
Here is another guy that went to college a little earlier than usual:
Education and career
Shaviv started taking courses at the
Israel Institute of Technology in Haifa at age 13.
[5] After a 3-year service in the IDF Unit 8200, he received in 1994 a Master of Science in physics and a doctorate during 1994–96. During 1996–99, he was a
Lee DuBridge Prize Fellow at
Caltech's TAPIR (Theoretical Astrophysics) group. During 1999–2001, he was in a postdoctorate position at the
Canadian Institute for Theoretical Astrophysics. In 2001–2006, he was a senior lecturer at Racah Institute of physics at the Hebrew University of Jerusalem. In 2006–2012, he was an associate professor, and full professor since 2012. Between 2008 and 2011, he was the head of the faculty union of the Hebrew University, and he served as the chairman of coordinating council of faculty unions between 2010 and 2014. In 2014, he became a member of the
Institute for Advanced Study in Princeton, and served as the chairman of
The Racah Institute of Physics between 2015 and 2019.
see
https://en.wikipedia.org/wiki/Nir_Shaviv
Shaviv just happens to agree with me re so called climate "science" that has predicted CO2 increase is causing "global warming" . The globe may be warming alright, but neither of us believe it's due in any significant way to CO2. We both believe CO2 is a very minor player, consequently we don't think any of the CO2 abatement measures will have any significant effect. (I'm in favor of them though for other reasons.) Shaviv and his colleagues have advanced an alternative hypothesis to explain global climate change and it is the only hypothesis that, so far, has proved consistent with
all the most reliable observations. I think he is most likely correct! If so he'll get the Nobel Prize in Physics, but probably postumously.