One hundred writers - including Neal Asher, Elizabeth Bear, Gregory Benford, Tobias Buckell, Brenda Cooper, Kathryn Cramer, David Langford, Tanith Lee, Ken Liu, Nick Mamatas, Norman Spinrad, Ian Stewart, Rachel Swirsky, Adrian Tchaikovsky and Ian Watson - offer their take on what the future will look like in Nature Futures 2, an anthology of sci-fi short stories from the award-winning Futures column in the science journal Nature.