Customer Reviews

Sidelights on Relativity

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This is the first book of I have read in which Einstein wrote directly rather than the many reiterations of his works. Sidelights on Relativity is a two part book of lectures in which he gave in 1920 and 1921. The first titled "Ether and the Theory of Relativity." Einstein explores the concepts given by Newton, Maxwell and Lorentz of the ether arguing the universe is not mechanical in nature. The other argument is the purely physical aspect in which the mechanical perspective seems to propose what is seen is that exists, and/or can be measured and proven to exist. That "space without ether is unthinkable," that is, the effects of spce/time gives credence to ethers existence just as "the undulatory surface forming the boundary between water and air alters the course of time." This, then, creates the contradiction. The second lecture is titled "Geometry and Experience" in which Einstein argues Euclidean geometry by noting the difference of experiencing and proposing laws of earth-measurement. He demonstrates this through the plane and the globe asking the reader to imagine the globe and a plane. While the plane is infinite in all directions, similarly one can fill the plane up infinately. This is not an all together accurate picture of our universe. Rather if we imagine a sphere and fill that up, we realize only a finite amount can fill up the space.

At this point, I will say that my understanding stands at a finite point in which it would be only arrogant for me to claim I understood the entirety of the book. Nonetheless, I found this book completely readable, mostly due to the fact that there are no formulas to follow. My knowledge of relativity is limited and I have given you what I believe I understand. Its a short book with the writing clear and concise and logical; which surprised me hearing stories about Einsteins genius in which he is unable to explain in laymans terms. Highly reccomended!

This 56-page Dover edition offers two lectures by Albert Einstein, "Ether and the Theory of Relativity" and "Geometry and Experience". The lectures are described as "devoid of complicated equations and abstruse terminology". Nonetheless, while the reader does benefit from Einstein's clarity of thought, these lectures do require careful attention. The first lecture presumes familiarity with physics; the second is largely a discussion of non-Euclidian geometry and is easier reading.

Ether and the Theory of Relativity, an address delivered on May 5, 1920 at University of Leyden:

Einstein recounts how the concept of ether originated and subsequently evolved. After some discussion of work by Hertz, Maxwell, Lorentz, and Mach, he notes that it became possible to take a position that ether does not exist. However, using an analogy of water waves, he explains that although the special theory of relativity does forbid us to assume ether consists of particles observable through time, the hypothesis of ether in itself is not in conflict with the special theory of relativity. Only we must give up ascribing a motion to it.

While it may seem superfluous to postulate a homogeneous, isotropic, ether-medium, Einstein contends that to deny the ether is ultimately to assume that empty space has no physical qualities at all. He then argues that according to his General Theory of Relativity "empty space" in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitational potentials). There can be no space or part of space without gravitational potentials.

After noting that elementary particles may be considered condensations of electromagnetic fields, he concludes that our current view of the universe presents two realties which are completely separated from each other conceptually, although connected casually, namely gravitational ether and electromagnetic field, or as they might be called, space and matter.

Geometry and Experience - an expanded form of an address to the Prussian Academy of Sciences in Berlin on January 27, 1921:

Einstein begins by posing and answering why mathematics, a product of human thought, is so admirably appropriate to describing reality. In exploring limitations associated with applying Euclidian geometry to relations between rigid bodies, Einstein introduces other axiomatic systems, including Riemann's geometry. He argues that there are difficulties in applying geometry on the sub-molecular level, but it is less problematical to extend the ideas of geometry to cosmic orders of magnitude.

After some clarification of the meaning of a finite universe and an infinite universe, he devotes several pages to illustrating how to visualize a finite, three dimensional universe that is unbounded. Einstein concludes this lecture with an enthusiastic comment: "My only aim today has to show that the human faculty of visualization is by no means bound to capitulate to non-Euclidian geometry."

Clear and important essay on the relationship between geometry and physics and our prejudices about it. Similar essay on the history of the ether and how it evolved to fit data. An unmatched depth of understanding presented succinctly and clearly. Good read for both those with passing understanding of relativity and those with deeper understanding who want to see Einstein's clear thinking on paper.

Albert Einstein is considered one of the greatest scientists of all time, and a quintessential embodiment of human genius. Einstein's ideas about the nature of space and time have forever revolutionized our understanding of these two most fundamental concepts. His ideas have been embedded into two theories of relativity - the special relativity and the general relativity. Both of these theories tend to be extremely conceptually difficult to grasp, but the latter one has an additional complication of being very mathematically demanding as well.

In this very short book Einstein aims to explain some of the basic ideas behind his two theories of relativity without being bogged down by the mathematical complexity. The book is written in a very accessible and straightforward language, and it's an absolute paragon of what scientific writing for general audience ought to look like. Because the ideas that are discussed are so basic and fundamental, this book has aged remarkably well and nothing could be either added or subtracted from it based on our most current understanding of relativity. Even if one day we come up with a theory that is even more fundamental than the relativity, it is a safe guess that Einstein's essential conceptual insights will still survive in one form or another.

It is quite rare that the general audience can have a clear and informative access to the writings of a great scientist. To have a book that accomplishes just that written by a man of Einstein's genius is priceless.

Fascinating lay explanations of Einstein's relativity theories from the man himself, including contextual (and competing) information relevant to the breakthroughs. No prerequisite mathematics knowledge needed, though comfort with basic kinetic Euclidian/Newtonian celestial motion (such as basic geometry and gravity) as well as abstract critical thinking skills are highly recommended.

Overall: 4 of 5.

This little book, Sidelights on Relativity, presents two lectures given by Einstein. The first, concerns the relation between the ether concept and general relativity. Einstein concludes that the concept of empty space in general relativity is an existing entity, which may have properties (in analogy to the ether), but these properties are not mechanical or material in any sense, neither solid nor fluid.

The second lecture, Geometry and Experience, gives a perfect example of the kind of property that empty space (modern version of the ether) may have. This property is that of 'curvature' which is the central concept of general relativity theory. He relates this concept to the geometrical measurements which are actually made in practice, in the sense of geometry as a physical science. He also gives some hints which may help the reader to visualize higher dimensional spaces. In addition, this lecture includes Einstein's famous remark "As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality".

For Newton, the space between particles was absolutely empty, consisting of exactly nothing. In the 19th century some physicists considered the possibility that space could be filled with a medium (ether) with material properties (solid or liquid) which could support vibrations (oscillations of motion). Einstein rejected both of these views and introduced the idea of a space which could have non-material properties but not material properties. This key concept has had an influence in both relativity theories and quantum theories, but its full implication has not yet been assimilated by our scientific culture. Thus this book may be of more significance than the title suggests.

This book is reminiscent of the book Essays in Science (Philosophical Library, 1930's) which is a collection of writings by Einstein on various scientific subjects. That book is abstracted from a still earlier work Mein Weltbild which gives Einstein's views on many topics including social issues.

It's heavy reading. There are very complicated concepts. It is still interesting to try to get a grip on. If you've had limited experience with certain mathematical concepts, you may not get a lot out of this.

I read This book and I would like to buy it. However I do not use Credit cards, only Debit cards, Best Regards, Professor Gerardo Paredes F