Spacetime Articles


tolman law beginner

Tolman Law in a Nutshell

The Tolman law describes how the temperature in a fixed gravitational field depends on the position (see for a pedagogic…
block universe time illusion

Does the Block Universe of Physics Mean Time is an Illusion?

I have written many Insights (and coauthored an entire book) explaining how the puzzles, problems, and paradoxes of modern physics can be attributed to…
symmetric spacetime

Slowly Lowering an Object in a Static, Spherically Symmetric Spacetime

In the first two articles in this series, we looked at the Einstein Field Equation and Maxwell's Equations in a static, spherically symmetric spacetime.…

Learn About the FLRW Metric and The Friedmann Equation

This article is part of our student writer series. The writer Arman777, is an undergraduate physics student at METUPrevious Chapter: A Journey Into…

The Schwarzschild Metric: GPS Satellites

 A Global Positioning System (GPS) device gives your precise location by receiving light pulses from satellites with synchronized clocks then…

Learn Spacetime in Mathematical Quantum Field Theory

The following is one chapter in a series on Mathematical Quantum Field Theory.The previous chapter is 1. Geometry.The next chapter is 3. Fields  2.…

Learn About Tetrad Fields and Spacetime

A spacetime is often described in terms of a tetrad field, that is, by giving a set of basis vectors at each point. Let the vectors of the tetrad be denoted…

Learn About Relativity on Rotated Graph Paper

This Insight is a follow-up to my earlier tutorial Insight (Spacetime Diagrams of Light Clocks). I gave it a different name because I am placing more…

Learn About Spacetime Diagrams of Light Clocks

We demonstrate a method for constructing spacetime diagrams for special relativity on graph paper that has been rotated by 45 degrees. Many quantitative…

Struggles With the Continuum: Point Particles and the Electromagnetic Field

 In these posts, we're seeing how our favorite theories of physics deal with the idea that space and time are a continuum, with points described…

Struggles With the Continuum: Is Spacetime Really a Continuum?

 Is spacetime really a continuum?  That is, can points of spacetime really be described---at least locally---by lists of four real numbers…