Galilean Transformation: Transformations made under the assumption that time and space measurements are independent of the observer.
Inertial frame of reference is one which is moving at constant speed where Newton's Laws of motion apply.
Simultaneity: If two events happen together, they are said to be happening simultaneously.
Light Clock: A beam of light reflected between two parallel mirrors that is used to measure time is called a light clock.
Proper Time is the time as measured in the frame of reference where the event it occurring. This happens to be the shortest possible time that can be recorded for an event to occur.
Proper Length:Proper length of an object is the length of an object as measured by an observer in the same frame of reference as the object. This is the longest possible distance of the object that can be measured.
Gravitational Mass: The gravitational mass of an object is the ratio of the gravitational force applied to an object and the strength of the gravitational field.
Inertial Mass: The force applied to an object divided by the acceleration it produces.
