Universe Articles

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Evidence for Big Bang

Universe FAQ ‘Is there Evidence for the Big Bang?’

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Evidence for the big bang can be provided from observational astronomy using Hubble’s law (redshift of galaxies) also known as the ‘Doppler effect’…
Cosmic Web Connections

The Evolution of the Universe, Cosmic Web and Connections

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The universe was not perfectly uniform when it started, some areas had higher density than others. During the evolution of the universe, these areas of…
bb_infinity2

Intro to Big Bang and Infinity Concepts

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This article is part of our student writer series. The writer Arman777, is an undergraduate physics student at METUIn the cosmology section of the…
journeycosmos3

A Journey Into the Cosmos - FLRW Metric and The Friedmann Equation

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

Coordinate Dependent Statements in an Expanding Universe

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In this Insight we will discuss the general Robertson--Walker (RW) universe, in which a set of co-moving observers with proper time ##t## observe the universe…
cosmosintro

A Journey Into the Cosmos - The Friedmann Equation

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 This article is part of our student writer series. The writer Arman777, is an undergraduate physics student at METUThis is an introduction…
inflation5

A Poor Man's CMB Primer: Quantum Seeds

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 The CMB establishes a record of ancient acoustic oscillations in the baryon-photon plasma. We've been studying how these primordial sound…
universestart

Where Did the Big Bang Happen?

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According to standard cosmological models, which are based on general relativity and are found to agree well with observations, time and space did not…
universeexpand

A Brief on the Expansion of the Universe

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The "ordinary Big Bang and expansion" (no inflation, no dark energy) Einstein's General Relativity allows a solution (FLRW metric) where an empty Universe…
lightcone7_3

LightCone7 Tutorial Part III - How Things are Computed

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In Part I and Part II of this mini-series, we have briefly discussed the basic user interface and the use of charts to depict the LCDM cosmological model.…
lightcone72

LightCone7Combo Tutorial Part II - Charts

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Part I dealt with the basic user interface of LightCone7. This part of the tutorial is about potentially useful cosmological insights to be gained from…
earlyuniverse

Was the Early Universe in a Disordered State?

No. The second law of thermodynamics says that entropy can only increase, so if the early universe had been in a state of maximum entropy, then the cosmos…
observableuniverse

Radius of the Observable Universe in Light-years Is Greater than Its Age

The radius of the observable universe is about 46 billion light years, which is considerably greater than its age of about 14 billion years. The radius…
steadystate

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

[Back in 2011, I wrote a FAQ entry for physicsforums on the steady state model and why it is no longer viable. I've learned more about the theory since…
blackholesuniverse

Is the Universe a Black Hole?

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In the early universe, matter was gathered together at very high density, so why wasn't it a black hole?The first thing to understand is that the Big…
universespinning

Can We Tell Whether the Universe Is Rotating?

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If you believe wholeheartedly in Mach's principle, then there is no way to test empirically for rotation of the universe as a whole, since there is nothing…
birthcmb

A Poor Man's CMB Primer: The Birth of a Cosmic Background Radiation

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 The early universe was hot. So hot, in fact, that nuclei boiled. The great thermal energy of the universe overwhelmed the confining efforts…
cmb

A Poor Man's CMB Primer: Orientation of the Universe

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 This is a picture of the cosmic microwave background:Fig 1. The cosmic microwave background as seen by the European Space Agency's…
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…