You are reading the word "now" right now. But what does that mean? "Now" has bedeviled philosophers, priests, and modern-day physicists from Augustine to Einstein and beyond. In Now, eminent physicist Richard A. Muller takes up the challenge. He begins with remarkably clear explanations of relativity, entropy, entanglement, the Big Bang, and more, setting the stage for his own revolutionary theory of time, one that makes testable predictions. Muller's monumental work will spark major debate about the most fundamental assumptions of our universe, and may crack one of physics' longest-standing enigmas.

The extraordinary life of Bernard Lovell began before the First World War and his story encompasses many of the great events of last hundred years: the Second World War, the invention of radio astronomy, the space race, the Moon landings, the exploration of the Solar System, the Cold War, the Cuban missile crisis and the defence of Britain against nuclear attack. It can now be revealed that he was also a spy. "He ranks as one of the great visionary leaders of science," Martin Rees, the Astronomer Royal, said of him. The great radio telescope which Lovell built became and remains one of the most important scientific instruments in the World. The Jodrell Bank Observatory and the Lovell Telescope have held their place at the frontier of research for fifty five years. This book seeks to explore succinctly and accessibly Lovell's life and achievements in the scientific and political context of the time. His legacy remains great, as can be seen from the extensive media coverage and personal tributes that his death in 2012 attracted all over the world. With the seventieth anniversaries of many wartime events in which he played a crucial role, as well as the recent declassification of information relating to his activities as an agent in the Cold War, this biography is sure to have a broad and timely interest.

This is the ideal resource for beginners and experienced stargazers in the United States and Canada, and has been updated to include new and practical information covering events occurring in North America's night sky throughout 2021. This practical guide is both an easy introduction to astronomy and a useful reference for seasoned stargazers. Now includes a section on comets and a map of the moon. Designed specifically for North America. Written and illustrated by astronomical experts, Storm Dunlop and Wil Tirion, and approved by the astronomers of the Royal Observatory Greenwich. Content includes: * Advice on where to start looking. * Easy-to-use star maps for each month with descriptions of what to see. * Positions of the moon and visible planets. * Details of objects and events in 2021. * Now in three editions: Britain and Ireland; North America; Southern Hemisphere.

This book discusses analogies between relativistic cosmology and various physical systems or phenomena, mostly in the earth sciences, that are described formally by the same equations. Of the two independent equations describing the universe as a whole, one (the Friedmann equation) has the form of an energy conservation equation for one-dimensional motion. The second equation is fairly easy to satisfy (although not automatic): as a result, cosmology lends itself to analogies with several systems. Given that a variety of universes are mathematically possible, several analogies exist. Analogies discussed in this book include equilibrium beach profiles, glacial valleys, the shapes of glaciers, heating/cooling models, freezing bodies of water, capillary fluids, Omori's law for earthquake aftershocks, lava flows, and a few mathematical analogies (Fibonacci's sequence, logistic equation, geodesics of various spaces, and classic variational problems). A century of research in cosmology can solve problems on the other side of an analogy, which in turn can suggest ideas in gravity. Finding a cosmic analogy solves the inverse variational problem of finding a Lagrangian and a Hamiltonian for that system, when nobody thought one exists. Often, the symmetries of the cosmological equations translate in new symmetries of the analogous system. The book surprises the reader with analogies between natural systems and exotic systems such as possible universes.