In this case, we use the present perfect.
The present tense describes facts which are generally true: the earth revolves around the sun, Peter sometimes reads romantic novels, Christmas comes but once a year.
The present perfect links a past time with a present state of affairs: something (I don't know what) happened in the past, and as a result you are now fascinated by the theory.
Similarly: "I have made a cake" (in the past, I made a cake; now you can have a piece); "Tim Burton has made many movies" (the movies are all in the past, but Tim Burton is still alive and still working in Hollywood, so his career continues into the present).
If you want to describe an action which began in the past and continues into the present, you usually use the present perfect progressive: "Since then I have been doing experiments to test the theory" (my first experiment was in the past, my last experiment was a short time ago, and I may do more experiments in the future).
Student or Learner