Einstein book and Einstein thoughts

Getting presents is not always easy especially if you you believe the presenter has put some thought into picking the present but failed due to lack of knowledge in the area of the present: Sometime in high school, for my birthday, a close friend gave me a cardboard circle of fifth so I could look up how many sharps there are in A major or G minor. That seemed like a good idea since I like to play music a lot. Except those kinds of things the cardboard display showed you are supposed to know and reproduce from memory (if not spinal cord) if you want to get into jazz improvisation. Thus, I could only produce some "uhm, thank you, how nice....".

Same thing happens with popular science physics books. I have not read any in many years since the density of information new to me is usually extremely low. Maybe I browse a bit in a book shop to see which topics are covered and read a page or two to see how a controversial topic is covered. I think this is the same for any worker in the field. Therefore, in the discussions of the controversial physics books of recent years, the authors' response to criticism of string theorists was often "you have not read the book" and indeed, this was true most of the time. But still, people haveing browsed through the book as above usually knew what was going on even without reading the book cover to cover.

That is the background to my reaction when my parents gave me a book for christmas which they had bought on their US trip in autumn: "My Einstein", a collection of essays edited by John Brockman. I assumed this would be just another Einstein book and one that was even a bit late for the Einstein year 2005. So the book sat on my shelf for a couple of months. But a few weeks ago I stated reading and was surprised: This was the most interesting book with a physics theme I have read in years! I can strongly recommend it!

The idea of the book is to ask 24 experts in fields related to Einstein's work or life to say what "Einstein" means to them. And the positive thing is that this is not 24 introductions to special relativity but 24 aspects of the physicist, the man, the pop star, the philosopher, the politician in 2006, more than fifty years after his death.

The authors include John Archibald Wheeler (the only one which actually interacted with Einstein), Lenny Susskind, Anton Zeilinger, Lee Smolin, George Smoot, Frank Tipler, George Dyson (the son of Freeman Dyson who was baby sit by Einstein's secretary), Maria Spirolulu, Lawrence Krauss and Paul Steinhardt. All of them find interesting and very diverse aspects of the Einstein topic and reading the book a number of physics questions came to my mind.

One essay was pointing out that what was peculiar about Einstein's way of thinking was that it was based on thought experiments and thus much more driven by elegance than by observation in the lab. This was illustrated by the fact that the reasoning that lead to special relativity was based on an analysis of Maxwell's equations (which are of course symmetric under Lorentz transformations, a fact which was known to Lorentz) rather than on an analysis of the Michelson Morley experiment.

One should note however that this argument is not logically tight: Of course it much more aesthetic to deduce from the fact that the speed of light comes out of Maxwell's equations that it should be universal and that if should be the same in all directions. However this does not follow directly as one can see by considering the acoustic analogue: From an analysis of kinetic gas theory one can deduce sound waves and the speed of sound can be expressed in terms of the molar weight of the gas etc. One finds a wave equation and that equation is invariant under boosts where the speed of light is replaced by the speed of sound. Under those acoustic Lorentz transformations, the speed of sound is the same in all frames. However, this is not a symmetry of the rest of nature and thus there is a preferred frame, the frame in which the air is at rest.

It could have been, that the world is invariant under Galilei transformations and Maxwell's equations hold only in a preferred frame (the rest frame of the ether say). This possibility cannot be ruled out by pure thought (like a Gedankenexperiment), one has to see which possiblity nature has chosen. And this is done in a Michelson Morley experiment for example.

But still: Buy that book and you will enjoy it!