Some crazies are talking about building laser-born black holes from solar energy, then in turn using those to either power trans-solar travel, or to build more black holes. This is full of mad science with lines like:

A nuclear laser can convert on the order of 10^−3 of its rest mass to radiation, we would need a lasing mass of order one billion tons to produce the pulse. This should correspond to a mass of order 10 billion tonnes for the whole structure (the size of a small asteroid). Such a structure would be assembled in space near the sun by an army of robots and built out of space-based materials.

Reading the whole paper is probably going to make your eyes roll back in your head, but the important bits have been sussed out by I09 and Next Big Future.