When "Time" magazine chose Albert Einstein as the person of the century for the 20th century it was due to his incredible intellectual achievements. Among those, two stand as particularly remarkable, becoming forever uniquely associated with their inventor, in minds of general public and professional scientists alike. These are the special and general theories of relativity. Their reputation is fully deserved. The two theories of relativity forever changed the way that we look at the space, time and matter. They touch upon our deepest understanding of physical reality and their core principles have stood the test of time, a remarkable achievement after a century full of usurpations of some of our most cherished notions.

The special and general relativity also have a reputation of being incredibly complex and hard to understand. In the case of special relativity this has primarily to do with the non-intuitive way that the world of four dimensions appears to us. In the case of general relativity, however, the complexity is substantially increased by the use of very advanced mathematical structures that it requires. And yet, all of the mathematical and conceptual implications of relativity stem from a few very simple ideas: the relativity of all reference frames, the constancy of the speed of light, and the equivalence of acceleration and gravitational field. It is a remarkable achievement of Russell Stannard's book to explain so much with just a very basic application of those principles. This makes it possible for a general reader to appreciate these beautiful theories without having to get bogged down in heavy mathematics. All examples in the book are intuitive and accessible. The illustrations are clear and serve to reinforce the main points in the text. One of the particularly remarkable features of this thin book is that it gives a full treatment of the "Twins Paradox" taking into the account the principles of general relativity - something that is usually brushed over in many other treatments.

The only problem with the book that I have concerns a few math examples that are used. The math notation is not quite clear, and even as simple a math symbol as a square root is printed in a very inadequate way. Also, there are a few glaring math mistakes (3/5 is not .67), but overall these are minor points that don't distract too much from the main content of the book.

I would strongly recommend this book as a good starting point for learning about relativity.