Is the practice of trascendental meditation allowed by halacha?
I am no expert in meditation. If the meditation is about self introspection and positive thinking etc. this might not be a problem but if it involves spiritual practices, philosophies and connecting with different forces, (which I believe they do) keep yourself far away from it. In any case it's not recommended, we have our own Jewish way of doing these kind of things (Shulchan Aruch OC 98) I think Rabbi Arye Kaplan has a book on meditation, if so he is always an inspiration and highly recommended.