Vedic Astrology requires Date of Birth, time and Place to buils one's horoscope....these three r truth.....It depends on Signs which r also present...It dependes on Planet transition on signs , that also happens...And it is a million years of deep observations based on which Theoris of Astrology is made...For example if Saturns and Mars comes face to face then there will be blood shed....this is true and observed...I will say that it is hypothesis Men has yet to discover many things...