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Why Does E=mc2? (And Why Should We Care?) Hardcover – July 14, 2009

4.1 out of 5 stars 183 customer reviews

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Editorial Reviews

From Publishers Weekly

British theoretical physicists Cox and Forshaw offer lay readers a fascinating account of modern scientists' view of the world, and how it got that way. Without using complicated mathematics, Cox and Forshaw show how the search for "mathematical consistency" can guide scientists in finding the "laws that describe physical reality." The authors provide the historical context that set the stage for Einstein's discovery, providing an easy-to-grasp explanation of counterintuitive experimental evidence, demonstrating how the speed of light acts as a "cosmic speed limit," the exception that proves the rule of relativity. The authors also clearly explain the tide shift that Einstein caused, transforming scientists' understanding of the world-"common-sense notions regarding space and time are dashed and replaced by something entirely new, unexpected, and elegant." Though the basics are covered in detail, there's plenty here for science buffs to ponder.
Copyright © Reed Business Information, a division of Reed Elsevier Inc. All rights reserved.


#5 on the paperback non-fiction list for the London Daily Telegraph, 6/26/10

Stephen Fry
“I can think of no one, Stephen Hawking included, who more perfectly combines authority, knowledge, passion, clarity and powers of elucidation than Brian Cox. If you really want to know how Big Science works and why it matters to each of us in the smallest way then be entertained by this dazzlingly enthusiastic man. Can someone this charming really be a professor?”

New Scientist, 6/24/09
“To get at the origins of E=mc2, the poster-child for Einsteins’s special theory of relativity, [Cox and Forshaw] must delve into deep principles of science and wield a good deal of mathematics. They do it well…They have blazed a clear trail into forbidding territory, from the mathematical structure of space-time all the way to atom bombs, astrophysics and the origin of mass.”

The Huffington Post, 7/8/09
“An account of relativity physics accessible to a wide range of various publics. If you're not a physicist (or not yet a physicist) and you want to understand what Einstein and relativity theory are all about, you would do well to read this book. The writing is clear, sparkling in places, and totally without vanity. Relativity theory, Einstein's supreme gift to us, is at the heart of the way science currently looks at physical reality, and anyone with an adventurous mind should be intrigued by what two smart physicists say about it in plain language…[A] delightful little book.”

Sacramento Book Review, 7/13/09
“It’s always fun when brilliant minds take on complex questions, particularly when said brilliant minds are happy to share their conclusions with readers, in reader-friendly and fascinating books such as Why Does E=mc2?...There is a great deal of knowledge and quite competent explanation throughout the book, which should serve as a dream come true for anyone who ever loved science, or wanted to learn more about it without having to go back to school. Come to this read with an open mind and a desire to learn, and you will come away with a treasure trove of knowledge."

Boston Globe, 7/19/09
“A mild-mannered, digressive, mostly math-free walk-through of the world’s most famous equation…[It] remind[s] us that Einstein’s equation is not some esoteric idea best pondered by scientific supermen, but a profound insight that continues to change lives…Cox and Forshaw’s enthusiasm for their material is plain…You will find them accommodating escorts.”

Infodad.com, 7/30/09
“Despite their formidable accomplishments and obviously outstanding intellects [Cox and Forshaw] are willing—and able—to unravel some Einsteinian thinking for the benefit of mere mortals. Why Does E=mc2? is a joy to read in part because of its juxtaposition of breeziness with complexity…Reading it is an intellectually exhilarating experience.”

Publishers Weekly online, 8/3/09
“Cox and Forshaw offer lay readers a fascinating account of modern scientists' view of the world, and how it got that way…Though the basics are covered in detail, there's plenty here for science buffs to ponder.”

SeedMagazine.com, “Seed Picks”, August 2009
“To move beyond a cursory understanding of Einstein’s iconic equation, put yourself in the adept hands of physicists and science educators Brian Cox and Jeff Forshaw. Using clear language and a few clearly explained equations, they demystify physics’ most counterintuitive claims.”

Discovery.com, 7/31/09
“As Brian Cox and Jeff Forshaw prove in this wonderful 264 page exploration of physics, Einstein's equation describes an elegant and succinct view of our universe, a view that is captured excellently in the text…Something of a page turner…It's the enthusiasm for physics in Why Does E=mc2? that is key, reinvigorating relativity and presenting it in a modern and entertaining light…A great read…By the time you reach the last page, you realize just how beautifully complex, yet elegant, our universe really is.”

Bookslut.com, August 2009
“[Cox and Forshaw] bend over backwards to reassure math-challenged readers…This is not only a painstakingly accessible explanation of spacetime, mass, particles, gravity, and a whole bunch of things that are just plain not simple. It's also an explanation, for non-scientists, of what physicists do, and why they want to do it.”

Bookviews blog, August 2009
“The authors provide a definition that anyone can understand and then apply it to some exciting science taking place right now…Read this book and I guarantee that it will make you the smartest person in the room!”

Flavorwire.com, 8/17/09
“Makes some of science’s most famous tenets easily accessible—even for those who barely passed sophomore chemistry…Crisp, engaging prose.”

GearDiary.com, 8/11/09
“Read this book if you are interested in your universe and if you have ever stared at a starry sky and wondered how the twinkling stars you were looking at sent their twinkle billions of years ago at the speed of light…A concise, captivating, passionate, and well written explanation of Einstein’s Mass Energy Equivalence.”

Internet Review of Books, September
“Written for an intelligent lay person who has an interest in the sciences. If you have taken high-school algebra, you have enough mathematics to follow the discussions…‘The universe is much richer than our everyday experiences would have us believe,’ Cox and Forshaw write, and their book amply demonstrates their assertion.” 

American Scholor, Autum issue
“Cox and Forshaw skillfully combine biography with a narrative of discovery, employing some of Einstein’s own thought experiments…I expected Cox and Forshaw to lament the current gaps in physics…But they are optimists tempered by hard doses of reality."

Physics World, August issue
“Pairs the enthusiasm of newcomers with the knowledge of experts…Cox and Forshaw have aimed their tour of gravity, mass and quantum weirdness squarely at the math-shy general public. Readers in this category should benefit from plenty of helpful and mostly non-mathematical explanations…With CERN’s Large Hadron Collider due to restart this autumn, the authors’ timing is impeccable…A useful reminder of how profoundly strange physics can appear to the novice.”

SciTech Book News, September issue
“Accessible to general readers…[Cox and Forshaw] offer lay readers an explanation of Einstein's theory and how it underpins our understanding of the workings of the universe—answering questions such as what energy and mass are, what light is and why stars shine, why nuclear power is more efficient than coal or oil—providing readers with an opportunity to explore their own notions of space and time.”

CoolHunting.com, “Back to School Essentials”, 8/28“By exploring each part of Albert Einstein’s famous equation, two physicists ultimately explain the theory of relativity.” (Science News, 10/24/09)
“Takes a riveting look at how Einstein’s famous theory of relativity relates to our modern world. Clear and concise, the entertaining book sheds light on the world of physics for the layman, effectively allowing even the most science-challenged audience to understand the complexities of the subject.”

Magill Book Review, October 2009
“Using minimal mathematics, the authors present an intriguing, accessible description of Albert Einstein’s special theory of relativity, how space-time relationships work, and why it is important in the modern world…Teaches readers who are not familiar with physics some complicated topics in a rather simple, straightforward, entertaining manner…Rewards of increased knowledge and insights as to how the universe works will be reaped from this book for all those who have any interest in physics and its many applications to everyday life.”

Charleston Post and Courier SC, 10/11
“A fun romp with science...The often amusing lecture by British physicists Brian Cox and Jeff Forshaw is written in plain language and full of fun examples.”

Science News, 10/24/09
“By exploring each part of Albert Einstein’s famous equation, two physicists ultimately explain the theory of relativity.”

Discover magazine’s Bad Astronomy blog

“Brian Cox and Jeff Forshaw have summoned up the audacity to write a book on relativity for lay people. Although this has been attempted before, it has rarely been done so well…Cox and Forshaw know their stuff…[They make] the science sound fresh and fun…The book quickly and painlessly explains why E=mc2…This book is a wonderful introduction into the wild world of stretchy time, warped space and unbelievable energies…Give this book a shot.”

MSNBC.com’s Cosmic Log blog, 11/24/09
“The restart of the world’s biggest particle smasher, the Large Hadron Collider, should spark interest in recently published books that delve into the big picture surrounding subatomic physics, such as Why Does E=mc2?

Manchester Evening News, 3/6/10
“Delivering cutting edge 21st century physics in a digestible form and publicizing science is [Cox&rsq...


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Product Details

  • Hardcover: 264 pages
  • Publisher: Da Capo Press; Advance Reader's Copy edition (July 14, 2009)
  • Language: English
  • ISBN-10: 0306817586
  • ISBN-13: 978-0306817588
  • Product Dimensions: 8.7 x 6.3 x 1 inches
  • Shipping Weight: 15.5 ounces
  • Average Customer Review: 4.1 out of 5 stars  See all reviews (183 customer reviews)
  • Amazon Best Sellers Rank: #723,143 in Books (See Top 100 in Books)

Customer Reviews

Top Customer Reviews

By Yvonne A. Oliver on August 23, 2009
Format: Hardcover Verified Purchase
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...
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Cox and Forshaw have presented a streamlined, focused popular science book aimed at teaching relatively new physics readers the basics and history of the famous equation in the title. While experienced physics readers will not likely learn new information, the book offers an approachable description of relativity, how we know it works, and why it is important in the modern world and beyond.

While I personally didn't gain much new from this book (as a reasonably experienced non-professional physics reader), I believe newer readers could be in for a treat. I'd certainly recommend starting a discovery of relativity with this book if the concept seems difficult. The authors take time to explain various points, and offer solid presentations and reasonable analogies to aid in the explanation. Combined with a singularly-focused subject, the book is an excellent starting point for curious, intelligent readers wishing to know more details about E=mc2. Four stars.
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Format: Hardcover
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
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My husband is a math guy and has read books about relativity for fun. I'm not so keen on math myself, but have a master's degree in organic chemistry (I can do math, sure, I just don't do it for fun). I bought this book so that we would have something to read together - I keep buying him books as gifts, and they often collect dust.

It turned out to be a great idea. We have often forgone watching TV in order to read more about E = mc2. We read, stop, discuss, and try to wrap our brains around the ideas. I think I have come to understand more of the underlying ideas briefly presented in my physics classes, and in an environment of no stress and no time limit! I am not in a position to critique the physics itself, but I have found no errors or issues that suggest a problem.

However, as much as the author's try to make the subject accessible, I am fairly certain my non-math and science family members would have been lost after the first few chapters. Without some experience in thinking in equations, it's just hard to wrap your brain around the ideas.

I would highly recommend this book to anyone with at least a basic math or science background who is interested in understanding something fundamental that hardly ever gets explained outside of an upper level physics course, or someone without a math or science background who is interested in really stretching their brain.
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The authors do a good job of describing the role on invariants in physics, and for that I am grateful.

However the way the choose to simplify the math and science created more confusion for me than light.

Their decision to not state the underlying formulas directly but instead to explain them in words required the authors to spread the formulas out over page after page making them unnecessarily difficult to follow. You cannot go back and review an equation because you can't find in buried in the text.

Page 22 is a good example of unnecessary explanation. It requires the entire page to laboriously explain that x, y,and z are variables. (Do the authors really believe someone would buy a book with the title E=mc^2 if they did not understand the concept of a variable??)

Minor point are belabored while major shifts are completely unexplained. For example, on page 80, the authors explain invariants in terms of the radius of a circle, all points on the circumference are equal (invariant) distance from the center. They explain that when this model is applied to space-time, it violates Cause and Effect. The explanation is enlightening; so far, so good. To fix the problem with cause and effect, the authors take a next step that is bizarre and unexplained. They change the Pythagorean formula to create a hyperbola and never explain how this new model of S/T maintains the invariance that was so obvious in the last model (the circle). Several commentators have noted this particular problem with book.

Another example from page 131-3 is even more bizarre. After demonstrating that (gamma)MC (the scaling factor of S/T time) is conserved, they then state the (gamma)MC^2 is also conserved (Ok, I will take your word on that ...).
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