Cosmology Articles

Tag Archive for: cosmology

infinite universe

Open, Flat, or Closed Universe: What Curvature Tells Us

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Direct answer: Cosmologists classify the universe as open, flat, or closed based on spatial curvature. Current cosmic microwave background (CMB) measurements…
dark energy supernova

Dark Energy Part 3: Fitting the SCP Union 2.1 Supernova Data

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In Part 1 of this 3-part series, I explained kinematics in Einstien-deSitter (EdS) cosmology and in Part 2, I explained kinematics in ##\Lambda##CDM cosmology…
dark energy cosmology lcdm

Dark Energy Part 2: LCDM Cosmology

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This is Part 2 of a 3-part series explaining evidence for so-called “dark energy” leading to a current positive cosmological acceleration. The evidence…
Dark Energy Cosmology Part 1

Dark Energy Part 1: Einstein-deSitter Cosmology

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In this 3-part series, I want to motivate the (re)introduction of the cosmological constant ##\Lambda## into Einstein's equations of general relativity…
Evidence for Big Bang

Big Bang Evidence: CMB, Redshift & Element Abundances

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Big Bang: Key PointsHubble's law (redshift of galaxies) and the Doppler effect provide direct evidence that the universe is expanding away from our…
Cosmic Web Connections

Cosmic Web Connectivity: How It Shapes Galaxy Evolution

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Introduction The universe was not perfectly uniform at the beginning; some regions had higher density than others. Over time these higher-density regions…
Gaia search for black holes

Gaia Astrometry: Detecting Gravitational Waves Guide

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Overview Gravitational waves (GWs) are disturbances in spacetime produced by massive objects moving asymmetrically. Only the most massive and most relativistic…
uranus spin

Why Uranus Spins on Its Side: Tilt, Theories, Models

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Uranus' Peculiar Tilt Uranus spins on its side. It has an obliquity (tilt) of 98° — its rotation axis lies closer to the ecliptic plane than any other…
black holes are not empty

VHE Gamma Rays from Sgr A*: Black Holes and CTA Observations

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Researchers simulating the accretion flow around Sagittarius A*, the supermassive black hole at the Milky Way's center, have found that magnetic reconnection…
What is Mass Inflation

Mass Inflation in Black Holes: Poisson-Israel Theory Explained

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Mass inflation is the phenomenon in which the internal mass parameter of a rotating or charged black hole grows without bound near the Cauchy horizon,…
Star Equations

Equations of State for Photon Gas and Relativistic Electron Gas

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This Insight develops equations of state that are useful in calculations about cosmology and about the insides of stars. The first calculation is for a…
isotropy definition

A Formal Definition of Large-Scale Isotropy

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This Insight is part of my attempt to develop a formal definition of 'large-scale isotropy', a concept that is fundamental to most cosmology, but that…
universestart

Did the Big Bang Have a Center? The Physics Explained

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The Big Bang did not happen at a single point in space, so it has no center. Standard cosmological models based on general relativity treat the Big Bang…
steadystate

What Is the Steady-state Model and Why It’s No Longer Viable

Introduction to the Steady State Model Back in 2011, I wrote a FAQ entry for Physics Forums on the steady state model and why it is no longer viable.…
CosmologicalHorizons

Inflationary Misconceptions and the Basics of Cosmological Horizons

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Introduction It is a common saying that during inflation "space expanded faster than the speed of light."  This statement is meant to articulate the…
neutrino

Learn About Neutrino Masses and Speed

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It was hard to miss the 2011 OPERA neutrino speed measurement that indicated superluminal neutrino speeds (and turned out to be a measurement error), but…