Tag Archive for: spacetime
![Kerr Spacetime](https://www.physicsforums.com/insights/wp-content/uploads/2021/10/spacetime-kerr.png)
Geodesic Congruences in FRW, Schwarzschild and Kerr Spacetimes
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Introduction
The theory of geodesic congruences is extensively covered in many textbooks (see References); what follows in the introduction is a brief…
![tolman law beginner](https://www.physicsforums.com/insights/wp-content/uploads/2021/04/tolman-law-beginner.png)
Tolman Law in a Nutshell
The Tolman law describes how the temperature in a fixed gravitational field depends on the position (see https://arxiv.org/abs/1803.04106 for a pedagogic…
![block universe time illusion](https://www.physicsforums.com/insights/wp-content/uploads/2020/09/block-universe-time-illusion.png)
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](https://www.physicsforums.com/insights/wp-content/uploads/2020/04/symmetric-spacetime.png)
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.…
![journeycosmos3](https://www.physicsforums.com/insights/wp-content/uploads/2018/01/journeycosmos3.png)
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…
![gps1](https://www.physicsforums.com/insights/wp-content/uploads/2017/12/gps1.png)
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…
![qft_spacetime](https://www.physicsforums.com/insights/wp-content/uploads/2017/10/qft_spacetime.png)
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.…
![spacetimetetrad](https://www.physicsforums.com/insights/wp-content/uploads/2016/08/spacetimetetrad.png)
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…
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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…
![](https://www.physicsforums.com/insights/wp-content/uploads/2016/06/featuredImage-Tutorial-TimeDilation.png)
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…
![spacetime4](https://www.physicsforums.com/insights/wp-content/uploads/2015/09/spacetime4.png)
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…
![spacetime](https://www.physicsforums.com/insights/wp-content/uploads/2015/09/spacetime.png)
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…