Timedilation seems clear when you study special relativity and read about the Hafele-Keating experiment. Gravitational redshift seems logical when you assume that light should lose energy when it is leaving a gravitational field. But the two seem to be contradictory to eachother. Question 1 :Do higher frequencies of clocks/light belong to high gravitational potential or to lower ? Question 2 :Why actually does light lose energy whereas a mass does not when it is leaving a gravitational field ?