# 1: The Special Theory of Relativity - Kinematics

- Page ID
- 9712

- 1.1: Time Dilation
- Time itself passes slower for an object is in motion.

- 1.2: Length Contraction
- If the time interval between two events depends on the relative motion of the observer, Einstein realized that the spatial separation between the events must also be observer-dependent.

- 1.3: Lorentz Transformation
- The Lorentz Transformation allows you to transform the spacetime coordinates of an event in one inertial reference system to any other inertial reference system.

- 1.4: Velocity Addition
- Since the Lorentz transformation allows you to relate the position and time of an event in one coordinate system to the position and time in any other coordinate system, it also allows you to relate quantities that depend on position and time, like velocity and acceleration. Therefore, using Lorentz we can derive equations that allow use to transform velocities measured by one observer to velocities measured by other observers.

- 1.8: Length Contraction and the Magnetic Force (Project)
- certain objects that are neutral in one frame of reference are actually electrically charged in other frames of reference due to length contraction. Moving charges (and hence electric currents) see these “charged-because-of-length-contraction” objects and feel electric forces of either attraction or repulsion. However, in our frame the objects are neutral so we “invent” a new force, magnetism, to make sense of the behavior of these moving charges.