Inevitably, year-end lists invite plenty of debate and criticism, and Scientific American's is no exception. Certainly, we could have included the discovery of new worlds beyond our solar system, including Kepler 22 b, an exoplanet in the "Goldilocks" zone of habitability, as well as the first known Earth-size exoplanets. Or noted the accumulating evidence suggesting that hydraulic fracturing, or fracking, to retrieve natural gas is likely to contaminate water supplies. (Final New York State regulations, expected in mid-2012, could determine the future of fracking in the U.S.)
Other candidates included the report of a new target against HIV, in which a doorway to infection (the so-called CCR5 receptor on immune cells) is blocked; the demonstration (using diamonds) that quantum entanglement can occur in everyday objects; and the MESSENGER spacecraft's photos of the planet Mercury, the first ever taken from orbit.
Some of our top choices could very well have an immediate effect on our lives. The impact of others may not be felt for years. Some discoveries may vanish altogether. We'll just have to see how things turn out in the years ahead. But no matter what, 2011 held big surprises in science and technology.