Tag Archive for: black holes
The Oppenheimer-Snyder Model of Gravitational Collapse: An Overview
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Part 1: OverviewPart 2: Mathematical DetailsPart 3: ImplicationsMost people who have spent any time at all studying GR are familiar with the…
Geodesic Congruences in FRW, Schwarzschild and Kerr Spacetimes
Introduction
The theory of geodesic congruences is extensively covered in many textbooks (see References); what follows in the introduction is a brief…
Gaia and the Race to Detect More Gravitational Waves
Gravitational waves (GW’s) are disturbances in spacetime produced by any massive object moving asymmetrically. However, only the most massive and most…
Black Holes Are Not Empty Voids
Black Hole Key PointsBlack Holes (BH’s) have a gravitational pull so strong that nothing, not even light, can escape it
BH’s can be divided…
What Are the Thermodynamics of Black Holes? A 5 Minute Introduction
Definition/Summary
The four laws of black hole thermodynamics are as follows...The Zeroth Law
Surface gravity [itex](\kappa)[/itex] is constant…
Exploring the Math in Killing Fields and Black Holes
Killing Vector Field
The Killing vector field is a vector field on a differentiable manifold that preserves the metric over spacetime (from this I assume,…
Black Holes and the Properties of In-Falling Radial Plungers
From 'Exploring Black Holes' by John Wheeler and Edwin Taylor; can apply to any object falling radially towards a static spherical mass (where the mass…
The Schwarzschild Geometry: Physically Reasonable?
In the last article, we looked at various counterintuitive features of the Schwarzschild spacetime geometry, as illustrated in the Kruskal-Szekeres…
The Schwarzschild Geometry: Spacetime Diagrams
When we left off in part 2, we were looking at the metric for the Schwarzschild geometry in Kruskal-Szekeres coordinates:$$
ds^2 = \frac{32…
The Schwarzschild Geometry: Coordinates
At the end of part 1, we looked at the form the metric of the Schwarzschild geometry takes in Gullstrand-Painleve coordinates:$$
ds^2…
The Schwarzschild Geometry: Key Properties
Not long after Einstein published his Field Equation, the first exact solution was found by Karl Schwarzschild. This solution is one of the…
Do Black Holes Really Exist?
Introduction
The purpose of this article is to discuss the title question from several different viewpoints, to show that it isn't as simple as it looks.…
Is the Universe a Black Hole?
In the early universe, the matter was gathered together at very high density, so why wasn't it a black hole?The first thing to understand is that the…
Learn Time Dilation and Redshift for a Static Black Hole
The following is an overview of the time dilation and gravitational redshift effects of a static (Schwarzschild) black hole. By general relativity, a strong…
Will All Matter Be Converted to Photons?
Will all matter be converted into black holes and then photons?
No. There is a misconception that a lot of laypeople seem to be picking up recently from…
An Equation for the Centrifugal Force Reversal Near A Black Hole
My goal in this article is to derive a simple equation for the proper acceleration of an observer traveling on a circular path around a Schwarzschild black…
What are the Fates of Massive Stars
Star Fate Key PointsStars are born in primordial nebulae, gaseous molecular clouds on the spiral arms of galaxies
Stars smaller than 1.4 suns…