I thought Newton's third law of motion (action-reaction) theory is only applicable in science world, but it has also real-world application. I'd rather call it (punishment-revenge) theory.
For example, a geek student learned computer science in 1980's, so all programming was done in C language. Eventually he grew up to be a more adult person. Then in 1990's Java came to the world of programming, which has made programming much much easier. This grown-up-geek-student turned up to be a professor in a very renowned university in United States. She or he was so intimidated with the emergence of Java language, saying that in her or his days "We struggled a lot for programming in C. Kids in these days should be given some lessons". So she or he decided to add a compulsory course for C programming, although in real recent world it is not the biggest language. Now her or his students are sharing the same pain she or he received during those 'ancient' days.
p/s : 'She' comes earlier than 'He' because 'She' is my current lecturer.
p/s : Yes, I'm whining on my C programming language. Haih...