# Tag Info

A white hole isn't formed. This is the definition. If $t$ is cosmic time, then a white hole is black hole that existed at $t=-\infty$. Take a look at this Penrose diagram. (Ignore the parallel universe piece.) The corner where $r=0$ and $r=\infty$ meets is called the past timelike infinity. We see that the white hole existed at that time. For a universe ...