Here's why:

* Dense Plasma: The Sun's core is incredibly dense, filled with a superheated plasma of ions and electrons.

* Frequent Collisions: Photons constantly collide with these charged particles, scattering them in random directions.

* Long Journey: Due to these collisions, a photon can take thousands, even millions, of years to travel from the Sun's core to its surface.

* Not a Straight Line: The path is not a straight line; it's a chaotic series of zigzags and turns, resembling a random walk.

This process is a key factor in the Sun's energy production and transport. While the nuclear fusion reactions occur in the core, the photons carry this energy outward, eventually reaching the surface and radiating into space as sunlight.