> We assume that light speed is a constant, but we also know that speed is measured as distance/time. Correct. However, the crucial part that is missing from y

> We assume that light speed is a constant, but we also know that speed is measured as distance/time. Correct. However, the crucial part that is missing from your thought process is that: 1) light can only travel in a "straight" line, and 2) "straight" lines are defined by the spacetime metric. As a lower-dimensional analogy, think of what a "straight" line means on the surface of a sphere[1]. The shortest path between two points is, by definition, a "straight" line, but if the space itself that the path is embedded in is curved, then when viewed from a higher dimension (i.e. on the surface of the sphere it's straight for you, but if you were in space) it would appear curved. The analogy fails when you attempt to think about it in higher dimensions, since humans have a very difficult time perceiving anything greater than the standard 3+1 spatial & time dimensions. But the math still holds. Light will always travel in a straight line, it just so happens that gravity redefines what "straight" actually means[2]. 1. http://mathworld.wolfram.com/GreatCircle.html http://mathworld.wolfram.com/GreatCircle.html 2. Explanation simplified for clarity.