Richard Feynman was a brilliant, creative teacher. In this volume he tackles some of the trickier subjects in physics. He starts slowly, even simplistically with a discussion of symmetry and builds one upon the other taking the reader through some relativistic topics and finally concluding with a fantastic description of space-time geometry. In a few short lessons, he showed me what had taken months at university to understand. I wish there were more teachers like him today.

Feynman is someone who I have kept bumping into during several months here and there. This lead to a point where I had to finally have a look and see if I understand him (I did, although I was more on sturdy ground in the beginning than in the end of this book, but I guess it's hard to be on a sturdy ground in a space rocket).

To some, it might sound strange that I read this for fun - physics has nothing to do with my work - but while reading, I actually laughed out loud. There was also a revolution in my head at one point when understanding something new. Some of the experiments still keep me baffled. Well worth reading!

Learn Relativity from the maestro Richard Feynman himself

In the introduction to this book, Roger Penrose, another great theoretical physicist of our times, states that "Relativity is not airy-fairy philosophy, nor is space-time mere mathematical formalism. It is a foundational ingredient of the very universe in which we live." On that note, it is encouraging for many readers that this book offers a great opportunity to take that extra step to learn the mathematical constructions for the effects of Lorentz transformations, Einstein's equations, relativistic dynamics; equivalence of mass and energy, Lorentz contraction and transformation of time. It requires undergraduate level physics, but comes with easy to follow instructions from the great maestro himself. Frequent references to his three volume book, Lectures in physics is valuable for readers who are familiar with his work.

Position and time measured in one frame of reference (one observer) is different from another frame of reference (another observer). Therefore Lorentz transformation must be examined to understand physical reality. When we look at an object, we find that it has an apparent width and depth, but they are not fundamental properties of the object, because if we look at it from a different frame of reference it would look different. In Lorentz transformations we see is a mixture of space and time. An event (physical reality) is defined by both space and time because the position of an object is characterized by the time. The description of the object also depends upon the frame of reference (observer). If the observer is travelling at the speed of light, his perception of the object would be different from someone in a stationary state. The difference between spacetime, and space and the interval provides interesting sense of reality. For example, anything happening to Sun "now" will affect earth only after 8 minutes (that is how long light takes to reach us.) Thus an event "right now" can not be defined, it is a mystery, because we are not affected by it right now, but can be affected later after eight minutes. The "now" is an idea or a concept of our mind, it is not physically definable at the moment, and we have to wait to observe it separated by distance in (light) time. The example of page 64 establishes that simultaneity is not a unique thing in the universe, because it means different things to different observers.

Relativistic dynamics; objects moving at high speeds (during forward motion) comparable to the speed of light shortens its physical length, and also time slows down (time-dilation) for the stationary observer, but the time remains the same for the moving astronaut. Thus for an observer moving under uniform velocity will not know he is in motion. The uniform velocity can not be detected without looking from outside, but the uniform rotation about a fixed axis can be detected without looking from outside. As noted earlier, the moving objects become heavier proportional to the speed given by the famous Einstein's equation, and at close to the speed of light the mass becomes enormous, and hence sufficient energy is not available to move anything beyond the speed o light.

There are many websites that explains the transition from Newtonian mechanics to the theory of relativity to explain physical reality. Some of them are referenced below, but is great to read Richard Feynamn, because he did not like scientific ideas without a good physical foundation, and his approach is strikingly original. His efforts are strenuous in teaching and making the reader understand the basic concepts. I especially recommend chapters 3 and 4 for a quick appreciation of the subject: Highly recommended to all readers interested in physics of reality.

Essential reading for relativity enthusiasts (of the weekend variety, I might add- the more academic ones might be better served by lectures given by the wild-haired maestro himself). Requires, and assumes, knowledge of Std XII Maths and Physics- you'll be pretty lost if you don't know what the hell differentials and integrals are. Though written in Feynman's casual, conversational style, the book never fails to make your head spin, and it's fun to put the book down on your chest in the middle of a chapter and think about how your reality ain't so real after all, dude...
I swear, science is drugs!