You probably have heard about Hubble telescope, which searches for the black holes in the universe. There is one more Hubble which searches for the black holes too. It is the project of University of Washington and it searches for the internet black holes. It explores IP network prefixes in real time and whether they are reachable by the path which is about them advertised in BGP. If the path is advertised, but the destination network is not reachable by it, the packets end in a virtual “black hole”. Good news is there is no such black hole in our local “star system” in Czech republic. Check your self whether the situation still remains the same on the Hubble project page.