I really enjoyed reading this book, because Ohanian covers some ground that I have not seen anywhere else, and he calls it the way he sees it. As a genuine trained relativist, he knows what he is talking about when he argues the physics.

However, I believe that he is a bit unfair to Einstein in calling him out for so many "mistakes":

- I do not agree that Einstein's argument for time synchronization was a "mistake": It was a REQUIREMENT following from the fact that no velocity of the Earth relative to the ether could be found. It is true that, if the Michelson-Morley result had given a positive result, Einstein's synchronization mechanism would have failed as being self-inconsistent, so in that sense it was an over-statement by Einstein to call his mechanism a "free act of will." But the argument itself is valid as an expression of what followed from the null result of M&M.

- The later argument by Swann that explained the Lorentz contraction in terms of dynamical effects was also valuable, but different. The preceding work by Lorentz and Poincare are also more in this school of thought: What do you expect to happen starting from Maxwell's equations and so forth? But these two approaches are both valuable and complementary.

- I do not agree that Einstein's argument for E = mc^2 is a "mistake". It is not valid as a mathematical proof, but it is an excellent heuristic argument. Given that it comes out of the blue, it is very suggestive, and convinces one that "there's gold in them thar hills." For a pioneer that is stumbling across this for the first time, it is like a miracle. The fact that more systematic and complete arguments are needed do not change that. Sometimes, to quote Feynman (on the discovery of the rules for calculating QED), "More truth can be known than can be proven."

The fact that Einstein chose to stick with his early arguments (of limited validity) is not really a mistake in my view: Why shouldn't a pioneer be proud to show his original tools of discovery? The professionals following after (like Planck) can and should do that. What is missing is that modern textbooks usually don't provide a full derivation either; but that is hardly Einstein's fault.

- Ohanian calls Einstein's arguments about meter-stick measurements on a rotating disk mistaken because they challenge the flatness of geometry in the non-rotating lab. However, as I read it, Einstein is just pointing out that the APPARENT geometry as measured by the physical meter sticks on a rotating disk are bound to look non-Euclidean. I do not believe there is anything wrong about what Einstein actually said here.

- Also in several other cases, Ohanian choses to call "mistakes" what we can see now are incomplete/heuristic arguments, or arguments where we would now chose to emphasize other aspects. It seems to me that Ohanian does this to give himself a unifying theme on which to base his book.

- Finally, I recently saw an article that pointed out that MOST scientific papers have mistakes. Nearly all papers (it claimed) turn out eventually to be wrong. In other words, progress in science entails a lot of back-and-forth, and the field as a whole progresses even as individual scientists change their minds one way or another. If this is true, then finding mistakes in Einstein's papers is no big deal; indeed, maybe the real point is that, since the topics addressed by the papers were significant, what can now be seen as errors are now seen to be significant as well.

Some readers (maybe most readers) will find Ohanian's writing style occasionally jarring: he sometimes uses informal language in a way that calls attention to itself and distracts from the story. Other reviews have pointed this out as well.

OK, so what was good about the book?

- The detailed explanation of the arguments was very revealing, even though I don't agree that they were all as "mistaken" as Ohanian condemns. He still provides an explanation of the context: What was the essential question being addressed, how does the argument work, where would we fault it today? This is very interesting, and provides the bread & butter of the book.

- Ohanian details some specific problems, and evaluations by current professional relativists, concerning the equivalence principle. He points out several ways in which it is quantitatively wrong. I guess the point is that it was a heuristic argument that helped Einstein in the right way at the right time, but doesn't have much bearing once you have the actual equations of general relativity. I now understand better some of the zen-like cryptic remarks made by a professor on this topic: Student: "I'm having some trouble actually understanding how the equivalence principle applies in this case ...". Professor: "Your lack of understanding is actually an indication of understanding the equivalence principle."

- Ohanian discusses the many attempts required to actually arrive at the correct equations for GR. Apparently, there is no cogent way to arrive at these equations from the general considerations from which Einstein was starting, although Ohanian describes a path starting from the spin-2 version of quantum field theory that eventually gets you there. So, unlike the case with special relativity, the creation of general relativity really was a leap in the dark.

- Contrary to most reviewers, I was fascinated by the "dirt" Ohanian was dishing on Einstein's financial and romantic affairs. I was totally unaware that he got around so much. In retrospect, this reminds me a bit of Richard Feynman.

- It was also interesting to hear that he was a bit full of himself, nearly fatally, when a young man. This really hurt his career, initially.

- It was very interesting to read that Einstein depended so much on assistants to do his calculations carefully and thoroughly. It seems odd; but it does clarify the point that there is a big difference between mathematics and theoretical physics. Most of the mathematicians I knew simply cannot really "get" physics; so now we know of a theoretical physics of genius who was just not very good at math. Obviously his revolutionary ideas and concepts were not really mathematical in origin or nature, even though some of them required high-powered mathematics to implement. Fascinating!

- Finally, it was very interesting to read Ohanian's deconstruction of the process by which Einstein became the most famous scientist of the 20th century. I had never questioned it; although I have always evaluated Niels Bohr as the most important scientist of the 20th century, for leading and supporting the development of quantum theory through his work with an international "college" of geniuses.

In short: I do recommend this book highly, even though I disagree with the somewhat cantankerous approach taken towards Einstein's "mistakes". It truly does prove James Joyce's point, quoted in the book: "A man of genius makes no mistakes; his errors are volitional and are the portals of discovery." I believe this applies more to Einstein than to Joyce!

Neal J. King