The infinite redshift surface refers to the infinite redshift of light on this surface, that is, the wavelength of light emitted from a boundary to any place is infinite, and this boundary is the infinite redshift surface
The infinite redshift surface generally appears in black hole Time and space, however, Minkowski spacetime There are also stable reference systems with infinite redshift surfaces. The infinite redshift surface is a two-dimensional hypersurface in the stable space-time, which satisfies that the wavelength of the outgoing optical geodesic from the surface to any point is infinite, That is, the redshift factor is infinite.
The infinite redshift surface can be expressed by the metric 00 component of the steady-state reference system in the steady-state space-time: hypersurface It is the infinite redshift surface for the following reasons: Consider the two steady state viewers G and G 'in the steady state space-time. The light emitted by G at point P is received by G' at point p '. Let the four speed of the viewer be , the four wave vector of light is , then according to the 3+1 decomposition of four wave vectors of light, the frequencies of light measured by G and G 'are and Due to the steady state, the four speed and time class of the viewer Field parallel, with , both sides use the four speed reduction index to merge Calculated in steady-state coordinate system, with Consider that the 0 th component of four speeds in the steady-state coordinate system is , substitute the above formula to get , so the two frequencies can be written as , due to The inner product of the field and four wave vectors is constant on the quasi optical geodesic, which is substituted into the We can get , infinite redshift request occurs Therefore, it is required to , certificate completed In 1960, Pound and Rebeka completed the first gravitational red shift experiment using Mossbauer effect, which verified the correctness of general relativity [1] 。
It is often said in popular science articles that the time required to fall into a black hole is infinite in the outside world. In essence, it is the red shift of the light emitted by the object when it falls radially, and the light emitted by the object is close to the infinite red shift surface (for Schwarzschild black hole The infinite redshift plane coincides with Event horizon ）The wavelength reaching the outside tends to infinity. Of course, this takes into account the gravitational redshift of the static viewer of Schwarzschild spacetime and the Doppler redshift 。 
