I have read about two black holes that will collide in a few hundred years. How will this affect Earth!
You have obviously read an article about the two black holes which are believed to exist in the central region of the galaxy NGC 6240 which is 140 million light years from us (for example this one from the NY Times). It has long been suspected that the nucleus of this galaxy might hold two black holes, and recent Chandra observations claim to have proven this to be the case. The black holes are in orbit around each other and as such will collide, however not for approximately a 100 million years (definitely not in a few hundred years). Black hole mergers may be happening all the time in external galaxies with no noticeable effects on Earth, therefore it is unlikely that this event will affect Earth at all.
This page was last updated on June 27, 2015.