## The Einsteinium Revolution – The Historical Roots of his Breakthroughs, by Hanoch Gutfreund and Jürgen Renn – a review

NB. I was sent this book as a review copy.

I started this book fearing that it would be just another tale of Einstein’s brilliance, the singular and incredible leaps in imagination that he took as a lowly patent clerk and of the enormous impact of his work. However, the book offered much more, proving far more intriguing. There are countless books out there (many of them very good) that detail his life and his works, but that see him very much as an isolated person, overturning the centuries old ideas of science and philosophy with paradigm shift after paradigm shift. This book paints a different picture in an incredibly compelling manner.

The book is really about the nature of science as Einstein found it, of the ideas and results that were already putting pressures on classical physics, and this is paralleled with the Copernican revolution, where the epicyclic models were grinding to a halt under their own complexity, and it took for someone to reimagine the results in a different light to see a much simpler and more elegant truth.…

## On the invariant measure in special relativity

I’m writing this for my string theory class. We are basing our lectures on Zwiebach – A First Course in String Theory, and starting off with special relativity. Not everybody in the class has a physics background (pure and applied mathematics students), and so there are likely to be questions which come up which show where I have to fill in some knowledge. We had a question about the invariant measure in special relativity (SR) and why there was a different sign in front of the time term compared with the space terms. I’ll do my best to explain here. Note that I am not explaining it in the precise chronological order of discoveries.

We start the picture off with relativity before SR – that is, Galilean Relativity. This simply states that the laws of motion are the same in all inertial (non-accelerating frames). That may sound straightaway like SR, but there’s a crucial ingredient missing which we will see in a bit.…

## Relativity, The Special and General Theory, 100th anniversary edition – by Albert Einstein

NB. I was sent this book as a review copy.

In 1917, two years after publishing his work on The General Theory of Relativity, Einstein published a popular science account of both The Special, and General Theories of relativity. It is with some embarrassment that I have to admit that I’d never read this before, despite taking a number of undergraduate and postgraduate courses in relativity. Einstein understood the importance that his results had on our understanding of the universe, but also that the profundity of them could not truly be grasped by the general public, despite the headlines which covered many newspapers around the world on his results, without a popular exposition. 1917 was the publication of the first edition of this explication, but he continued to update them up until 1954. This allowed him to extend the theoretical discussion with the experimental verifications and discoveries which occurred over the next decades, including that of the expanding cosmology, spearheaded by Hubble’s observations.…