alt Hacker NewsIt's common, most of the people I know from the UK system did their PhD in 3-4 years.
In Europe you just study what it says as well. You happy to do a bachelor's in physics, your classes are all physics. You don't read shakespeare and learn french.
You can also do this in high school, so you can from age 16 be studying just physics and math.
I did none of my degrees in US, and my physics degree was 95% math and physics. Physics degree is quite sequential anyway. You can't do QM in your first year or QFT in your second year.
I've checked random people I know from oxford and none started after 3-year undergrad and those how did after 4 all did 4 year dphil (small sample size warning). 4+4 is reasonable.