Abstract

In 1805, Einstein noted that a spherical wave at a speed of light has the equation x² + y² + z² = c²t². But the proper derivation yields 3c²t² on the right-hand side of the equation. This error has been perpetuated until the present day. A well known College physics textbook, for example, derives the Lorentz Transformations of length and time starting from the above equation. All the various derivations of the mass variation with speed in STR are based on these Lorentz Transformations. A few comments are made on the thermodynamics of mass increase with speed.