IB PHYSICS Option A: Relativity

Reference frame

A system that defines an object's position using coordinates and time events, providing a perspective for observation.

Inertial frames of reference

Frames that are non-accelerating and move at constant velocity relative to each other, with no absolute stationary frame in the Universe.

Galilean Relativity

The principle that objects in inertial frames move in straight lines with constant velocity unless acted upon by force, corresponding to Newton's first law.

Cartesian coordinate system

A system commonly used for reference frames, representing points in space in 3D and 2D.

Lorentz transformations

Equations that establish the connection between values in different reference frames, superseding Galilean transformations when dealing with speeds close to that of light.

Einstein’s Two Postulates of Relativity

First, the laws of physics are the same in all inertial frames; second, the speed of light in vacuum is constant in all inertial frames.

Simultaneity in Special Relativity

The concept that events being simultaneous depends on the observer's reference frame, contrasting with Galilean relativity where simultaneity was absolute.