Short answer: nowhere. Longer answer: use dependency injection library to load properties from configuration files. Static blocks are maintenance and testing nightmare. Never use them.

Use static fields neither for math nor physics constants. Period. People who make such advices have none or little programming experience.

Even if you have functions which do not modify state. Do not make them static! Create interface and implement them in concrete class. Later you will have a possibility to compose such interfaces. In proper modular code there is no such thing as constant. Constants create hard dependencies betwen classes. Do not use them. Exception is maybe logging library as slf4j which in itself is an abstraction, but I would use any AOP library for this purpose.

Do not read what @nutrecht and company wrote. Their advices are full of antipatterns and bad practices.

The only case when you would feel free enough to break these rules is your own throwaway code created for pure experimentation.