Entries by stevebd1

Killing Vector Field & Surface Gravity in Kerr BH Explained

Killing Vector Field The Killing vector field is a vector field on a differentiable manifold that preserves the spacetime metric. In other words, it generates an isometry of the metric. Although the Killing vector that corresponds to time translation is timelike (c^2 dt^2 > dr^2) at spatial infinity, it need not be timelike everywhere outside…

Radial Infall into a Static Mass: Equations & Guide

From Exploring Black Holes by John Wheeler and Edwin Taylor. The relations below apply to any object falling radially toward a static, spherically symmetric mass (assuming the mass of the infalling object is much smaller than the central mass). Types of radial infall Drip — dropped from rest at ro Rain — dropped from rest…

Time Dilation & Redshift of Schwarzschild Black Holes

Time dilation near a Schwarzschild black hole The following is an overview of the time-dilation and gravitational-redshift effects of a static (Schwarzschild) black hole. By general relativity, a strong gravitational field can slow down time. The closer you get to the event horizon of a black hole (if you could survive the tidal gravity gradients…