This book provides the reader with a detailed and captivating account of the story where, for the first time, physicists ventured into proposing a new force of nature beyond the four known ones - the electromagnetic, weak and strong forces, and gravitation - based entirely on the reanalysis of existing experimental data. Back in 1986, Ephraim Fischbach, Sam Aronson, Carrick Talmadge and their collaborators proposed a modification of Newton’s Law of universal gravitation. Underlying this proposal were three tantalizing pieces of evidence: 1) an energy dependence of the CP (particle-antiparticle and reflection symmetry) parameters, 2) differences between the measurements of G, the universal gravitational constant, in laboratories and in mineshafts, and 3) a reanalysis of the Eötvos experiment, which had previously been used to show that the gravitational mass of an object and its inertia mass were equal to approximately one part in a billion. The reanalysis revealed that, contrary to Galileo’s position, the force of gravity was in fact very slightly different for different substances. The resulting Fifth Force hypothesis included this composition dependence and also added a small distance dependence to the inverse-square gravitational force. Over the next four years numerous experiments were performed to test the hypothesis. By 1990 there was overwhelming evidence that the Fifth Force, as initially proposed, did not exist. This book discusses how the Fifth Force hypothesis came to be proposed and how it went on to become a showcase of discovery, pursuit and justification in modern physics, prior to its demise. In this new and significantly expanded edition, the material from the first edition is complemented by two essays, one containing Fischbach’s personal reminiscences of the proposal, and a second on the ongoing history and impact of the Fifth Force hypothesis from 1990 to the present.

Sometimes the only path forward is through the past. Two things you need to know: The earth is dying and time travel is real. We have exhausted, no, abused, the fossil fuels of this planet and now we're facing a self-inflicted extinction level event. Our only hope, my team of Time Inflectors must travel back in time in order to save all of our futures. Earth is on the verge of extinction. We have limited crude oil and our primary fuel sources are negligible. The carbon clouds signal the end of our species. We have but a few options: leave the planet… or fix it. We are the TFA, a special Canada-based agency that stumbled across a revolutionary discovery. The fifth Elemental force. Time. We built a freaking time machine based on the new physical sciences, believing we can go back to the “inflection points” of this extinction level event and fix things. The irony here is that the fuel we need to operate the invention, is the very fuel that led us to this juncture. Even with the precautions in place we only have enough for a limited number of time jumps, 5 to be exact. To make things even more difficult, time travel has a few additional “restrictions” as the discovery of time as a fundamental force provides a Quantum and Physical science sandbox. This means that the tachyons that interact with matter do so similarly to protons and neutrons; they cannot engage in something that would create a paradox. In layman's terms, they prohibit certain interactions between those from the future and those in the present. I’m Doctor Malik Fikai, one of the three Inflectors tasked with going back and fixing this mess before it happens, otherwise our future is history.

Relativity theory assumes locality, without accounting for the observer's past history. This work introduces nonlocality, or history dependence, into relativity theory. Inertia and gravitation are deeply tied, suggesting gravity may be nonlocal. The gravitational memory of past events must then be taken into account

In No Easy Answers, Allan Franklin offers an accurate picture of science to both a general reader and to scholars in the humanities and social sciences who may not have any background in physics. Through the examination of nontechnical case studies, he illustrates the various roles that experiment plays in science. He uses examples of unquestioned success, such as the discoveries of the electron and of three types of neutrino, as well as studies that were dead ends, wrong turns, or just plain mistakes, such as the "fifth force," a proposed modification of Newton's law of gravity. Franklin argues that science is a reasonable enterprise that provides us with knowledge of the natural world based on valid experimental evidence and reasoned and critical discussion, and he makes clear that it behooves all of us to understand how it works.

Fascinating blend of history and anecdote, combining official accounts with the reminiscences of the veterans themselves.

Beyond Einstein: Perspectives on Geometry, Gravitation, and Cosmology explores the rich interplay between mathematical and physical ideas by studying the interactions of major actors and the roles of important research communities over the course of the last century.