The thought experiment proposed by Langevin in 1911, known under the popular names, 'Clock Paradox' or 'Twin Paradox', is the most surprising result of the theory of Relativity: A twin who travels to a star at nearly the velocity of light comes back to Earth and finds his twin brother much older. In over a century, several thousands of published articles debated both in favor of and against this result. Unique to the physics of Relativity, this baffling phenomenon is analyzed as a main goal of this book.Among an incredible number of solutions, is there one of simplicity and clarity which may be accepted unanimously by all of the physics community? The answer is yes and this solution, which has its origin in Einstein himself, is developed in the framework of the Special Theory of Relativity. In detailing this solution, it is shown that the essential ingredient to understand the theory is the acceleration of the twins. All the models which do not include acceleration are incompatible with the original idea of Langevin. If one considers this phenomenon, several questions come to mind. Why did physicists debate excessively on the paradox and struggle to reach an agreement? Why was there resistance to integrate acceleration into their studies? Why is the solution developed in this book known only by a minority of scientists?Written for physicists, historians and philosophers of science, this book seeks to answer these questions based on (1) the psychological difficulty to accept the theoretical results, and (2) the fact that scientific knowledge is not uniformly distributed among scientists.

This is a story of two twins, Timmy and Tommy, and their nine and a half months of life before birth.

Beneath their perfect family façade, twin sisters struggle alone with impossible circumstances and their own demons until they finally learn to fight for each other in this poignant tour de force from #1 New York Times bestselling author Ellen Hopkins. Sixteen-year-old Kaeleigh and Raeanne are identical down to the dimple. As daughters of a district court judge father and a politician mother, they are an all-American family…on the surface. Underneath run very deep and damaging secrets. What really happened in the car accident that Daddy caused? And why is Mom never home, always running far away to pursue some new dream? The girls themselves have become hopelessly divided over the years. Sick of losing Daddy’s game of favorites, Raeanne turns to painkillers, alcohol, and sex to dull her pain her anger. Kaeleigh tries to be her father’s perfect little flower, but being the misplaced focus of his sexual attention has her seeking control anywhere she can—even if it means cutting herself and unhealthy binge and purge eating. Secrets like the ones the twins are harboring are not meant to be kept—from each other or anyone else. Before long, it's obvious that neither sister can handle their problems alone, and one must step up to save the other, but the question is…who?

"A unique window into human behavior and development." —Steven Pinker The riveting story of two sets of identical twins separated at birth and improbably reunited as adults, a dream case for exploring nature and nurture. Accidental Brothers tells the unique story of two sets of identical Colombian twin brothers who discovered at age 25 that they were mistakenly raised as fraternal twins—when they were not even biological brothers. Due to an oversight that presumably occurred in the hospital nursery, one twin in each pair was switched with a twin in the other pair. The result was two sets of unrelated “fraternal” twins—Jorge and Carlos, who were raised in the lively city of Bogotá; and William and Wilber, who were raised in the remote rural village of La Paz, 150 miles away. Their parents and siblings were aware of the enormous physical and behavioral differences between the members of each set, but never doubted that the two belonged in their biological families. Everyone’s life unraveled when one of the twins—William—was mistaken by a young woman for his real identical twin, Jorge. Her “discovery” led to the truth—that the alleged twins were not twins at all, but rather unrelated individuals who ended up with the wrong families. Blending great science and human interest, Accidental Brothers by Nancy L. Segal and Yesika S. Montoya will inform and entertain anyone interested in how twin studies illuminate the origins of human behavior, as well as mother-infant identification and the chance events that can have profound consequences on our lives.

In Victorian London, thirteen-year-old Lucy's comfortable world with her loving parents begins slowly to unravel the day that a bedraggled woman who looks exactly like her mother appears at their door.

When her health begins failing, the mysterious author Vida Winter decides to let Margaret Lea, a biographer, write the truth about her life, but Margaret needs to verify the facts since Vida has a history of telling outlandish tales.

Kate DiCamillo meets Lemony Snicket in this darkly comic novel about two sisters who learn they are each others' most important friend! Imagine two twin sisters, Arabella and Henrietta--nearly identical yet with nothing in common. They're the best of friends . . . until one day they aren't. Plain and quiet Henrietta has a secret plan to settle the score, and she does something outrageous and she can't take it back. When the deed is discovered, Henrietta is sent to live with her eccentric great-aunt! Suddenly life with pretty, popular Arabella doesn't seem so awful. And, though she's been grievously wronged, Arabella longs for her sister, too. So she hatches a plan of her own and embarks on an unexpected journey to reunite with her other half.