Quantum physics is notable for its brazen defiance of common sense. (Think of Schrödinger's Cat, famously both dead and alive.) An especially rigorous form of quantum contradiction occurs in experiments with entangled particles. Our common assumption is that objects have properties whether or not anyone is observing them, and the measurement of one can't affect the other. Quantum entanglement rejects this assumption, offering impeccable reasoning and irrefutable evidence of the opposite. Is quantum entanglement mystical, or just mystifying?

Macroeconomics takes a broad perspective on the economy of a country or region; it studies economic changes in the aggregate, collecting data on production, unemployment, inflation, consumption, investment, trade, and other aspects of national and international economic life. Policymakers depend on macroeconomists' knowledge when making decisions about such issues as taxes and the public budget, monetary and exchange rate policies, and trade policies-all of which, in turn, affect decisions made by individuals and businesses. 

In Waves, Fredric Raichlen traces the evolution of waves, from their generation in the deep ocean to their effects on the coast. He explains, in a way that is readily understandable to nonscientists, both the science of waves themselves and the technology that can be used to protect us against their more extreme forms, including hurricanes and tsunamis.

Billions of people around the globe use various applications of spatial computing daily - by using a ride-sharing app, GPS, social media check-ins, even Pokemon Go. Scientists and researchers use spatial computing to track diseases, map the bottom of the oceans, chart the behavior of endangered species, and create election maps in real time. Drones and driverless cars use a variety of spatial computing technologies. Spatial computing works by understanding the physical world, knowing and communicating our relation to places in that world, and navigating through those places.

Humans are hard-wired for collaboration, and new technologies of communication act as a super-amplifier of our natural collaborative mindset. This volume in the MIT Press Essential Knowledge series examines the emergence of a new kind of social collaboration enabled by networked technologies. This new collaborative society might be characterized as a series of services and startups that enable peer-to-peer exchanges and interactions though technology.