HaLeiVi, please cite your source. Science and Math are, in fact, necessary for learning Gemara. The sugya regarding the minimum shiur of a round sukka is a case in point.
As for studying Kabbala, Rav Ashlag differentiates between taamei mitzvot and practical Kabbala, which is only for those who have mastered Shas and poskim and reached a very high level of observance. However, in any case, that Zohar seems to say that one who is not ready will be prevented. When Rabbi Hiyya was a bachur he wanted to join Rabbi Shimon and Rabbi Eliezer but a wall of fire surrounded their house. There are also stories about people falling asleep as soon as the shiur started and waking up as soon as it was over. Interestingly, the Maharshal was very upset when he heard that the Arizal, who was his grand-nephew, had begun to learn Kabbala. He wrote him a very harsh letter in which he threatened to put him in cherem. The Arizal wrote back very respectfully explaining why he had done so.