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

4.02  ·  Rating details ·  7,158 ratings  ·  421 reviews
The most accessible, entertaining, and enlightening explanation of the best-known physics equation in the world, as rendered by two of today’s leading scientists.

Professor Brian Cox and Professor Jeff Forshaw go on a journey to the frontier of 21st century science to consider the real meaning behind the iconic sequence of symbols that make up Einstein’s most famous equatio
Hardcover, 249 pages
Published July 1st 2009 by Da Capo Press (first published 2009)
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Denise Nader I wouldn't say "easily", but nonetheless, the effort was satisfying. Although no background in STEM is necessary, I would say that having read other…moreI wouldn't say "easily", but nonetheless, the effort was satisfying. Although no background in STEM is necessary, I would say that having read other scientific divulgation books is. At least, having read about relativity, cosmology, astronomy and similar subjects, because this book is very specific and assumes you are familiar with certain theories.(less)

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4.02  · 
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 ·  7,158 ratings  ·  421 reviews

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Courtney Johnston
I loved this book, and it wasn't just that cheeky Brian Cox going on all the time about being covered in tweed and chalkdust (somebody please hand me a fan).

'Why does E=mc2' is my fifth book from the Royal Society science book shortlist. If Marcus Chown is magical cellulite cream, this is physics bootcamp - no corners cut, no let's-take-it-easy-today-shall-we. Cox and Forshaw don't just want to explain this equation - they want you to understand it, to understand its power (predictive and descri
Aug 02, 2017 rated it really liked it
Shelves: physics
Cox and Forshaw pack Einstein’s theories of relativity and much more into 250 pages. They state upfront that their book is intended to be challenging. And it is, despite simplistic analogies and explanations tucked in between some pretty dense material. Their underlying premise is “From the simplest of ideas”. Einstein noticed that Maxwell had shown that the speed of light was a constant and from this he constructed the Special Theory of Relativity. Then Einstein thought about the fact that all ...more
I was expecting, from the first few paragraphs of the book, that I was going to breeze right through this. It didn't really happen that way. I had to take college physics, which included the basics of relativity and quantum theories, so I probably have a bit more knowledge than the average non-physicist. All the same, there were areas of this book that just did not seem to click at all, even after reading paragraphs over and over again. Usually the parts that didn't click were the "easy" example ...more
Jun 22, 2012 rated it did not like it
Absolutely senseless. If he ever gets close to talking about the matter at hand, another long passage about a motorcyclist will pop up to "explain things"

Look. The reason you use so many horrible analogies is because you are a horrible explainer! Convey it the first time, don't waddle about.
Feb 24, 2010 rated it really liked it
On a good day, high school physics class used to leave me feeling kind of (for lack of a better word) high. This book brought back that old, familiar feeling, but in an even better way. In the end, I walked away with a much clearer understanding of Einstein's theories of special and general relativity than I ever achieved slogging through high school physics. (I think our teacher must have been unable to articulate and synthesize the underlying questions that the equations sought to answer.) The ...more
Apr 27, 2016 rated it liked it  ·  review of another edition
Shelves: science
Have you watched Wonders Of The Universe with Brian Cox? You should. And afterwards, when you’ll read this book, his voice and passion will accompany you all along.

For me it wasn’t a breakthrough experience, but if one’s not familiar with the theory of relativity and physics concepts of space and time, it will be a more than pleasant reading, for it is written in a very accessible language, with day to day examples and a bit of humor on occasion.

And you can even accompany your reading with
David Drent
Feb 25, 2018 rated it it was amazing  ·  review of another edition
I would love to say that I understood every word and every example of this book, but unfortunately there were many times I felt like the concepts were far too complicated for me. I'm not an unintelligent person but my math and physics knowledge is rather old and rusty.
I'll give it another 2 or 3 read through before making any firm judgements on the books.

I feel I have learned something from this book...I just don't know what it is I've learned..
Jan 13, 2010 rated it liked it
Shelves: science
I’ve got rather mixed feelings about this one. I think writing a simple account of very difficult material is hard to achieve and so every such effort should be praised wherever it is found – but there is a fine line between simple and patronising and I’m not sure this one respects that line all of the time.

It is clear these guys know their stuff, but I found it hard to concentrate on parts of this book as they would go into a longish chat about how hard the maths is and so how they have made t
Bob Nichols
Feb 29, 2012 rated it it was ok
For those trying to nudge themselves into Einstein's world a little more, this book's title has great appeal. At some very general level, the equivalence of energy and mass can be understood, but the role of light ("c") and light squared remains a challenge.

The authors do a good job of describing how mass converts to energy (heat/photons/light carry away mass; when wood burns, energy is released and mass is reduced). In the reverse, energy adds to mass. When energy (heat) is added to mass, mass
Dec 26, 2011 rated it it was amazing
Superb review of latest in particle physics and spacetime. Cox explains things as clearly as possible, but I believe I will need to reread this before I could begin to explain any of it to anyone else. Check out Cox's (who's a prof at Manchester U and a scientist at CERN, working on the Large Hadron Collider) wonderful videos on YouTube.
Dec 07, 2014 rated it really liked it
Shelves: science-physics

Who was this Adventure in Space-Time Written For?

The challenge of writing any popular science book is that the audience has different levels of knowledge. The author needs to choose the appropriate level of knowledge to aim the writing at. It follows that the reader’s appreciation of the book depends on what they know. To understand my perspective, you should know my background:

A long time ago I completed first year university science before switching into computers. I have since read a number o
May 10, 2019 rated it it was amazing
Shelves: science
Omg I had no idea how shallow my understanding of relativity was!! Eye opening & exciting read. A bit difficult to follow at times and I still have a few technical questions that I'll need to look-up myself, but I still learned a lot!
While the progress we've made is astounding, I can't help but feel a bit of despair at the thought of how this progress was achieved sometimes (see the Minkowski spacetime "why not try Pythagora's theorem with a minus sign???") and all the "forced" assumptions
Carlos Martinez
Jun 17, 2019 rated it really liked it
An entertaining and not-entirely-impossible guide to Einstein's physics. I enjoyed reading it, but it'll take me at least one more go to master the main concepts.
(I never say this, but thank goodness I read this book in Hungarian. It was difficult enough without having to try and decipher what are the Hungarian equivalents of all the terms.)

I have been meaning to read this book every since it came out in Hungarian, but now it seemed like just the light summer read I needed… which, of course, it isn’t, but I’m fairly certain that I’d find some parts of it very complicated even in winter, so what the hell. My main motivation to read this book was Brian Cox
Jan 08, 2014 rated it it was ok
Well, thank the gods that's over! I bought this as further reading on an iTunes U course I'm doing, thinking that it would offer further insight. The first half of the book is so patronising that I could barely bring myself to claw through it (but unfortunately I have a Magnus Magnusson approach to reading). This merely added to the annoying impression that the authors are explaining all the n a s t y, d i f f i c u l t s c i e n c e y - w i e n c e y v e r y s l o w l y t o y o u. B e c a u s e ...more
Jun 29, 2012 rated it it was ok
Why is E=mc^2? It was an enormous ask, and Cox and Forshaw were never going to deliver.
It is easy reading, but unless you understand maths you won't get it at all.
When I read on page 77 "although we did not prove (the maths)" I began to feel cheated, and then they tried to explain in several thousand words space-time vectors, which could have been done in two lines of maths, then I thought to myself it would have been much easier if they had used the maths throughout, and dispensed with all thos
JJ Coetzer
Mar 28, 2013 rated it really liked it
this is a great read, very interesting, but it is not a book I would suggest to anyone who does not have a understanding of astrophysics, the book does start of easy to understand, but it does get complicated
Oct 29, 2017 rated it really liked it  ·  review of another edition
"In following the book up to this point, you may well be juggling a lot of mental balls as you read this sentence". Cox and Forshaw say this at some point halfway through the book, but it might as well be applied to my feelings when finishing it. I don't really know how to criticize, comment or even rate it (for the most of the reading I was pretty sure I would leave no rating at all). I started in August, read a couple of chapters and loved it; never had I understood relativity and physics so w ...more
Aug 07, 2019 rated it really liked it
So, first of all, this is a lovely little introduction to relativity, both special and general, produced with just the right amount of math to make all the concepts clear without too many confounding and always unhelpful analogies (though at times it did feel a bit patronizing – they spend quite a while explaining, for example, the concept of a variable that, if you don’t already have in your toolbox, pretty likely means you will not be able to follow any of the math anyway).

Now, how this was su
Bruno Espadana
Aug 15, 2019 rated it really liked it
Einstein’s theory of special relativity for dummies. Which, in this case, is probably most of us.
It will be hard for someone to come up with a simpler way to explain Einstein’s work - if you’re well versed on maths or physics, you will probably find this annoying or maybe too dumbed down. But this isn’t for you - it’s for all people that are curious about Einstein and our universe, can follow a logical discussion, but are not technical enough to follow a more detailed explanation. Not that this
Rachel Welton
Nov 18, 2017 rated it really liked it
There are some books that are enhanced by metamorphosis into audiobook, and others that need to remain firmly in the realm of the written word. Jeff Forshaw manfully reads out the equations but I couldn't manage to conjure them up in my mind's eye.
The numerous analogies were enlightening, and I certainly feel I have learned things that I didn't know before, however often there was a big, unexplained leap from analogy to completion, possibly at the speed of light, or failing that at the square r
Nov 08, 2017 rated it really liked it  ·  review of another edition
Shelves: non-fiction
Fantastic book if you're interested in physics or just want to know the actual science behind the worlds most famous equation. They authors do a fantastic job explaining everything, building on what's come before, so that buy the time to get the the complicated theoretical stuff you're not completely lost.
Naveen Gwalia
Jul 13, 2019 rated it it was ok
Shelves: audio-book
I listened to the audio book,dont you do that.even if the author says otherwise,this book is to be read because it involves lots of math.there was no surprise elements in this book which is the main spur for me to put one more star.maybe since i have already read some bestseller books of this genre i didnt find one.i wont recommend you to read this book if you have limited time.
Huw Evans
Aug 22, 2011 rated it it was amazing
Shelves: science
Brain (sic) Cox is one of the current pin-up boys of science; ex pop musician, he is now a physicist working at the LHC in Switzerland when he isn't gadding about the world for his latest TV series or recording The Infinite Monkey Cage for BBC Radio 4 (listen if you get the chance - it is brilliant). There are many explanatory books about the theories of Relativity, most of which are so up there own backsides that they are unreadable unless you have a degree in theoretical physics. Cox and Forsh ...more
Feb 20, 2012 rated it it was amazing
Recommends it for: did wong
I've been a fan of Brian Cox for years. His infectious enthusiasm, his ability to boil down complex concepts for an average dude without a physics degree, and his clear passion for what he does, make him compelling viewing.
So after seeing him and Jeff Forshaw lecture on the subject of this book, I decided to get a bit more in depth and check out the book.
It’s excellent. The guys are able to help me to understand and visualise relativity. This is easier said than done with such a counter-intuitiv
May 28, 2011 rated it it was ok
Shelves: science
From the man that bought us the 1997 New Labour election theme tune, comes a book about the origins and meaning of Einstien's E-Mc2.

The main problem with the book is there is far too much going on about 'deeper understanding' and time spent telling us how things are being explained to us poor intellectually subnormal non physicists in v e r y s i m p l e t e r m s so we can keep up.

If you can get over the condescending tone, and the jumbled narrative (too many tangents), the information is easy
Apr 03, 2012 rated it it was amazing
Shelves: favorites
I loved this book - it actually takes you through the processes of deriving e=mc2 and provides the necessary context on people and theory to understand the meaning behind what this equation means. Good detail. Good big picture. Also sheds some light on the experiments the lovely people at CERN are doing. I had to re-read several sections (some many times) to really get it but it was well worth it. The math gets pretty deep towards the middle (you can skip it, but it's there if you're inclined to ...more
Nov 20, 2009 rated it liked it
I felt like this book went back and forth between being written in real simple terms to being hard to follow mathematics written in narrative form. It went back and forth between being exciting to being boring in its presentation of equations, and that's coming from a math major who enjoyed every math class I had in school. Some of the concepts in the book, which are considered by some to be basic and foundational to modern physics, are truly fascinating to ponder. I love stretching my brain thi ...more
Oct 09, 2011 rated it liked it
This was really well written for the lay person, covering the early history of physics and how we came to these equations and what we use them for...but I had to renew the book at the library for another month because one isn't enough to fully absorb all the information this book covers. I'm sure it's a breeze for an MIT student, but since it was written for my level of science (meaning zero) I need more time to wrap my brain around these concepts that are completely new to me (because my high s ...more
John Rauch
Dec 01, 2013 rated it really liked it
The information in this book was incredible. The delivery sometimes made it more difficult than necessary. I don't believe that every book should have to be "beginner" level, but if you're going to claim that anyone can read it, maybe spend a little extra time working out some good analogies to explain simple concepts or give explanations that don't always require advanced math to grasp. I think I understood the majority of the book, but there were some sections I had to read multiple times to u ...more
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Science and Inquiry: September 2013 - Why Does E=MC2? 4 92 Sep 23, 2013 05:12AM  

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Brian Edward Cox, OBE (born 3 March 1968) is a British particle physicist, a Royal Society University Research Fellow, PPARC Advanced Fellow and Professor at the University of Manchester. He is a member of the High Energy Physics group at the University of Manchester, and works on the ATLAS experiment at the Large Hadron Collider (LHC) at CERN, near Geneva, Switzerland. He is working on the R& ...more
“In science, there are no universal truths, just views of the world that have yet to be shown to be false.” 19 likes
“Our experience teaches us that there are indeed laws of nature, regularities in the way things behave, and that these laws are best expressed using the language of mathematics. This raises the interesting possibility that mathematical consistency might be used to guide us, along with experimental observation, to the laws that describe physical reality, and this has proved to be the case time and again throughout the history of science. We will see this happen during the course of this book, and it is truly one of the wonderful mysteries of our universe that it should be so.” 7 likes
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