Special Relativity - Vocabulary Flashcards

Glossary-style vocabulary flashcards covering the key terms and definitions from the Week 2 notes on Special Relativity.

Special Relativity

Theory (1905) describing how observers in inertial frames (no acceleration) measure time, length, and mass differently for moving objects, with the speed of light remaining constant.

General Relativity

Einstein's theory (1915) addressing gravity and acceleration, predicting phenomena like black holes.

Inertial Reference Frame

A reference frame moving at a constant velocity (no acceleration) in which Newton’s laws hold.

Principle of Relativity

There is no experiment in a closed reference frame moving at constant speed that can determine its uniform motion.

Constancy of the Speed of Light

The speed of light in vacuum is the same for all observers, regardless of the motion of the light source or observer.

Speed of Light (c)

Approximately 300,000 kilometers per second in vacuum; universal speed limit.

E = mc^2

Mass–energy equivalence; energy and mass are interchangeable; moving objects gain relativistic mass.

Time Dilation

Moving clocks are observed to run slower than stationary clocks.

Length Contraction

Objects moving relative to an observer are measured to be shorter along the direction of motion.

Relativistic Mass Increase

The apparent increase in an object's mass as its speed approaches the speed of light.

Space-Time

The four-dimensional continuum that combines three spatial dimensions with time.

4D Space-Time

A model with 3 spatial dimensions plus 1 time dimension used to describe motion.

3 Dimensions of Space

The three spatial axes (length, width, height) along which objects can move.

1 Dimension of Time

The single temporal axis along which events occur.

Invariance of c (Relativity of Light Speed)

Light’s speed remains unchanged across all reference frames and observer motions.

Relativity of Motion (Galilean heritage)

The concept that motion is relative; early work by Galileo laid the groundwork for Einstein's theory.

Uniform (Non-accelerating) Motion

Motion with constant velocity; no net acceleration.

Reference Frame

A coordinate system used to measure positions, times, and motions of objects.

Relativity of Space

Space is affected by the invariant speed of light, leading to length contraction in the direction of motion.