Why Does E=mc2?: (And Why Should We Care?)

Francis Ford Coppola has said that happiness consists on learning new things every day. People like Brian Cox and Jeff Forshaw help us to become happier. Scientists like these who devote part of their precious time to divulge scientific ideas are the real missionaries of the XXIst century helping to extend the gospel of science, which, contrary to other gospels, it is non dogmatic and subjected to possible disproval by experiment , a feature of science introduced by Muslim scientists (!) according to the book (page 40). The book is not only, as it title suggests, an explanation of the famous Einstein formula but a very up-to-date and understandable review of XXth century physics, including cosmology, special and general relativity and the Standard Model with its awe inspiring master equation. The book uses, sometimes, very simple mathematics, which the authors suggest the math averse reader to skip, if necessary, but with important results. For instance, making use of the very famous, old and simple Pythagorean theorem Cox and Forshaw prove that the half life of muons accelerated to 99.94% of the speed of light is extended, due to relativistic effects, 29 times, a fact that is verified experimentally. There are also several examples of theoretical predictions confirmed experimentally which is one of the beauties of physics. Fred Hoyle's prediction of an energy level of the carbon nucleus which makes it crucially possible the synthesis of heavier elements in the stars, gravitational waves (whose existence has been indirectly confirmed studying a double pulsar) , the masses of the W and Z bosons (confirmed at CERN), the existence of the positron posited by Dirac or Chandrasehar's limit for the mass of white dwarves. The story unfolds from Faraday's experiments and Maxwell's equations which lead to the constancy of the speed of light which, in turn, lead to the Special Theory of Relativity, to Minkowski's space time, the conservation of the energy-momentum vector and the famous E=mc2 formula (which is an approximation, by the way). The final chapters are devoted to General Relativity (and its clear effects on the GPS system), the Standard Model (with a good introduction to gauge symmetry) and the Higgs boson, the last particle, among the fundamental particles of the model, to be found experimentally (in the Large Hadron Collider hopefully when they get it working) . There are also some curiosities such as that if the Earth was flat we would see a laser fired horizontally bending to its surface. To sum up: a very entertaining book that I hope will make you happier. It made me.

It's a great feeling to come back tired from work and pick up such a book. After all, like most people I rarely have time to ponder seriously about the universe and the meaning of time and space.I am a high school French teacher so my training in science is rather limited. But after a few hours spent thinking about time,space, distance, energy and matter with Cox and Forshaw,I felt enlightened and rejuvenated! It really read like a thriller, whenever I put the book down I could not stop thinking about it and at dinner I could not shut up about it. The more my friends asked me questions about what I read the more I felt like going back and re-reading until I could explain it in my own words. Now that I am done with it, it's haunting me, driving home or playing with my cat; it keeps me thinking...

As an avid reader of popular science, only a handful stand out as masterpieces. This is one such book. The authors will take you on a journey in a logical order that leads to many 'light bulb' inspirational moments along the way. The book has at its heart the principles of relativity and uses this to deftly explain the interwoven relationship between mass-energy and spacetime. I am eagerly awaiting the authors next collaboration.

E = mc2 The energy contained in anything is equal to its mass multiplied by the speed of light. As the title of this book suggests this book seeks to answer the twin questions of why nature should work this way and why we should care that nature works this way. Like all basic questions the ones posed in this book actually turn out to be quite instructive about why nature works the way it does. Though admittedly we still have much more learning to do about whys and wherefores of this process this book was great in making the connection that there is a correlation between the mass of a thing and the potential energy it contains. Burn a log and it weighs less. Start a uranium reaction and mass itself is extinguished in the process producing energy that travels at the speed of light. Why the energy produced from such a reaction should travel at the speed of light tells us much about what Oxford's John Barrow would term the impossibilities of science...inherent limits to nature and how it operates that give us useful guides to understanding it better. And understanding nature, as both Einstein and Spinoza would have us believe is understanding God, "the old one," himself...reason as good as any why we should care. This book is highly recommended.

I read Professors Cox & Forshaw's new book on Einstein's E = mc2 in one day: I couldn't put it down. I have tried for years to get a handle on the equation and how to think about spacetime, have read many books for the lay public (I am a psychiatry professor, so I am a layman when it comes to physics) -- and this new book is the only one that I could grasp and that really made sense. It's a great tribute to the authors and a great service to the public. Michael H Stone, MD