If you throw a ball gravity pulls it down. The harder you throw it the farther it will go but it is still constantly being pulled down by gravity. If you look at a photon even it will get pulled down by gravity but the photon will go a lot farther before it would hit the ground. Now if you were to view this photon on a very short interval wouldn't the photon be going in a straight line and then kind of step down towards the ground due to planck length. Just think of the floor and ceiling functions in math. I don't understand how the planck length could even make sense with this because the photon can't be moving slightly down on anything smaller then the planck length. As usual, I probably just don't know everything about the subject and have a lack of understanding. Thanks in advanced.