What Is Spacetime?

This section provides a quick introduction of speed, which is a mathematical model used to describe our universe in frame of references that combines space and time together.

What Is Spacetime? Spacetime is a mathematical model used to describe our universe in frame of references that combines space and time together. A coordinate system with 4 dimensions can be associated with a spacetime frame,

Everything in our universe is made up by a set of events. Each event can be mapped to a point in a specific coordinate system associated with a specific spacetime frame of reference.

For example, we can define a spacetime frame of reference and coordinate system in spacetime as describe below:

With this frame of reference and coordinate system defined for spacetime, we can describe some events with coordinate numbers now:

Since 4-dimensional coodinate systems are very difficult to draw on paper, we can only try to illustrate spacetime by removing the z-axis as shown in the picture below:

Spacetime with a Frame of Reference and Coordinates (fsu.edu)
Spacetime with a Frame of Reference and Coordinates

Last update: 2014.

Table of Contents

 About This Book

 Introduction of Space

 Introducion of Frame of Reference

 Introducion of Time

 Introduction of Speed

 Newton's Laws of Motion

 Introduction of Special Relativity

 Time Dilation in Special Relativity

 Length Contraction in Special Relativity

 The Relativity of Simultaneity

Introduction of Spacetime

What Is Spacetime?

 What Is World Line?

 What Is Light Cone?

 Moving Frames and Galilean Transformation

 Galilean Diagram of Moving Frames

 Minkowski Spacetime and Diagrams

 References

 PDF Printing Version