Light does a Bender

Gravity bends spacetime (spacetime is 3 dimensions of space, one of time). In the diagram, the space is seen as two dimensions, and the earth bends it as if it were a rubber sheet.

If you have a black hole instead of the earth, the singularity inside the black hole actually punctures the sheet. A "singularity" is our name for classifying the unclassifiable. When matter is squeezed into nothingness, physics breaks down completely. The "black hole" is actually a name for the area inside of which nothing can escape. The terms "black hole" and "event horizon" mean the same thing, whereas "singularity" is the term for the thing in the middle of it all.

The straight lines in the diagram are called geodesics (light paths), and as is clear, they are bent.

So light, although composed of massless photons, is affected by gravity, because gravity is not really an attraction, but a geometric effect.

OPINION:

This is one reason why I believe gravity will never be united with the other three forces, which are gauge fields. Gravity is not a gauge field, but geometry.