In February of 2011 we started posting free nonfiction we at Baen thought might be of interest to our readers. The first article was "The Size of it All" by Les Johnson, a Baen author and space scientist. As new nonfiction is made available, it will be posted on the main page, then added to this book (to save the Baen Barflies the trouble of doing it themselves). This is our compilation of nonfiction for 2015. As is usual with such copyrighted material from Baen, the contents may be copied and shared but NOT sold. All commercial rights are reserved to Baen Books.