In Yore Deah the Rema brings that learning Physics and metaphysics is a part of learning Torah,. Even though the is a famous note from the Gra on this  Rema in Yore Deah, I was one day in the Yeshiva of the Gra in the old city of Jerusalem and saw an extended commentary on the notes of the Gra. On that note it was brought that it was inserted and not at all from the Gra. [Before the notes went to the printer someone inserted this comment that supposedly shows that the Gra disagreed with the Rema on that point.]