# Every black hole may hold a hidden universe – space – 23 July 2010 – New Scientist

WE COULD be living inside a black hole. This head-spinning idea is one cosmologist’s conclusion based on a modification of Einstein’s equations of general relativity that changes our picture of what happens at the core of a black hole.

In an analysis of the motion of particles entering a black hole, published in March, Nikodem Poplawski of Indiana University in Bloomington showed that inside each black hole there could exist another universe (Physics Letters B, DOI: 10.1016/j.physletb.2010.03.029). “Maybe the huge black holes at the centre of the Milky Way and other galaxies are bridges to different universes,” Poplawski says. If that is correct – and it’s a big “if” – there is nothing to rule out our universe itself being inside a black hole.

In Einstein’s general relativity (GR), the insides of black holes are “singularities” – regions where the density of matter reaches infinity. Whether the singularity is an actual point of infinite density or just a mathematical inadequacy of GR is unclear, as the equations of GR break down inside black holes. Either way, the modified version of Einstein’s equations used by Poplawski does away with the singularity altogether.

via Every black hole may hold a hidden universe – space – 23 July 2010 – New Scientist.