### Explore the Odyssey of Photons in Curved Spacetime!

**Odyssey_Edu is a free educational software for visualizing the photon trajectories, or light rays, around a Kerr black hole in real-time.**

Photon trajectories around a rotating black hole are not trivial and must be computed using the theory of general relativity. In the framework of general relativity, gravity is described through the geometry of spacetime. Mathematically, the spacetime around a non-rotating and rotating black hole is described by the **Schwarzschild metric** (discovered in 1916) and the **Kerr metric** (discovered in 1963), respectively. Therefore, sometimes we refer to them as a “Schwarzschild black hole” or a “Kerr black hole”.

The above image (created by Odyssey_Edu) demonstrates the effect of the frame-dragging, an effect caused by the rotation of spacetime around a Kerr black hole! Due to this effect, light rays must co-rotate in the same direction that black hole rotates when they approach closely enough to the black hole (within the outer white oblate surface).

Odyssey_Edu is developed using the GPU-based general relativistic radiative transfer code, Odyssey.

Chinese website of Odyssey_Edu is available here .