In his original paper of 1905, "On the Electrodynamics of Moving Bodies", Einstein described a procedure for synchronizing distant clocks at rest in any inertial system K. Clocks thus synchronized may be said to be in standard signal synchrony in K. It has often been claimed that there are no logical or physical reasons for preferring standard signal synchronizations to any of a range of possible non-standard ones. In this paper, the range of consistent non-standard signal synchronizations, first for any (...) one inertial system, and second for any set of such systems, is investigated, and it is shown that the requirement of consistency leaves much less room for choice than is commonly supposed. Nevertheless consistent non-standard signal synchronizations appear to be possible. However, it is also shown that good physical reasons for preferring standard signal synchronizations exist, if the Special Theory of Relativity yields correct predictions. The thesis of the conventionality of distant simultaneity espoused particularly by Reichenbach and Grunbaum is thus either trivialized or refuted. (shrink)

After discussing in the first five sections the meaning and the difficulties of the principle of relativity we present a new sel of spacetime transformations between inertial systems (“inertial” transformations), based on three assumptions: (1) The two-way velocity of light is c in all inertial systems and in all directions; (2) Time dilation effects take place with the usual relativistic factor; (3) Clocks are synchronized in the way chosen by nature itself, e.g., in the Sagnac effect. We show that our (...) new transformation laws can explain the available experimental evidence in spite of the implied noninvariance of the one-way velocity of light. (shrink)

Our sharpest and most original social critic goes "undercover" as an unskilled worker to reveal the dark side of American prosperity. Millions of Americans work full time, year round, for poverty-level wages. In 1998, Barbara Ehrenreich decided to join them. She was inspired in part by the rhetoric surrounding welfare reform, which promised that a job -- any job -- can be the ticket to a better life. But how does anyone survive, let alone prosper, on $6 an hour? To (...) find out, Ehrenreich left her home, took the cheapest lodgings she could find, and accepted whatever jobs she was offered. Moving from Florida to Maine to Minnesota, she worked as a waitress, a hotel maid, a cleaning woman, a nursing-home aide, and a Wal-Mart sales clerk. She lived in trailer parks and crumbling residential motels. Very quickly, she discovered that no job is truly "unskilled," that even the lowliest occupations require exhausting mental and muscular effort. She also learned that one job is not enough; you need at least two if you int to live indoors. Nickel and Dimed reveals low-rent America in all its tenacity, anxiety, and surprising generosity -- a land of Big Boxes, fast food, and a thousand desperate stratagems for survival. Read it for the smoldering clarity of Ehrenreich's perspective and for a rare view of how "prosperity" looks from the bottom. You will never see anything -- from a motel bathroom to a restaurant meal -- in quite the same way again. (shrink)

This book gives an excellent introduction to the theory of special relativity. Professor Resnick presents a fundamental and unified development of the subject with unusually clear discussions of the aspects that usually trouble beginners. He includes, for example, a section on the common sense of relativity. His presentation is lively and interspersed with historical, philosophical and special topics (such as the twin paradox) that will arouse and hold the reader's interest. You'll find many unique features that help you grasp the (...) material, such as worked-out examples,summary tables,thought questions and a wealth of excellent problems. The emphasis throughout the book is physical. The experimental background, experimental confirmation of predictions, and the physical interpretation of principles are stressed. The book treats relativistic kinematics, relativistic dynamics, and relativity and electromagnetism and contains special appendices on the geometric representation of space-time and on general relativity. Its organization permits an instructor to vary the length and depth of his treatment and to use the book either with or following classical physics. These features make it an ideal companion for introductory courses. (shrink)

A rotating disk with angular acceleration is given a relativistic description as observed from the rotating rest frameR of the disk. It is shown how a non-Euclidean intrinsic spatial geometry develops inR, as the disk gets an angular velocity. The explanation of this as given by anR-observer is discussed. A recent description of the geometry inR presented by Grünbaum and Janis is criticized. The motion of light as described by use of coordinate clocks inR is discussed in connection with some (...) recent work by R. C. Jennison and coworkers. The significance of the difference between directed signals and circular waves when clocks inR are to be synchronized by means of light emitted from the axis inR is made clear. (shrink)