Editing Cosmic microwave background (section)

=== Precision cosmology ===
Inspired by the COBE results, a series of ground and balloon-based experiments measured cosmic microwave background anisotropies on smaller angular scales over the{{Which|date=June 2024}} two decades. The sensitivity of the new experiments improved dramatically, with a reduction in internal noise by three orders of magnitude.<ref name="Komatsu2022Review">{{Cite journal |last=Komatsu |first=Eiichiro |date=2022-05-18 |title=New physics from the polarized light of the cosmic microwave background |url=https://www.nature.com/articles/s42254-022-00452-4 |journal=Nature Reviews Physics |language=en |volume=4 |issue=7 |pages=452–469 |doi=10.1038/s42254-022-00452-4 |issn=2522-5820|arxiv=2202.13919 |bibcode=2022NatRP...4..452K }}</ref> The primary goal of these experiments was to measure the scale of the first acoustic peak, which COBE did not have sufficient resolution to resolve. This peak corresponds to large scale density variations in the early universe that are created by gravitational instabilities, resulting in acoustical oscillations in the plasma.<ref>
{{cite book|last=Grupen|first=C. |date=2005|title=Astroparticle Physics|pages=240–241|publisher=[[Springer Science+Business Media|Springer]]|isbn=978-3-540-25312-9|display-authors=etal}}</ref> The first peak in the anisotropy was tentatively detected by the [[Mobile Anisotropy Telescope|MAT/TOCO]] experiment<ref>
{{cite journal|last=Miller|first=A. D.|date=1999|title=A Measurement of the Angular Power Spectrum of the Microwave Background Made from the High Chilean Andes|journal=[[Astrophysical Journal]]|volume=521|issue=2|pages=L79–L82|doi=10.1086/312197|bibcode=1999ApJ...521L..79T|arxiv = astro-ph/9905100 |s2cid=16534514|display-authors=etal}}</ref> and the result was confirmed by the [[BOOMERanG experiment|BOOMERanG]]<ref>
{{cite journal|last=Melchiorri|first=A.|date=2000|title=A Measurement of Ω from the North American Test Flight of Boomerang|journal=[[The Astrophysical Journal Letters]]|volume=536|issue=2|pages=L63–L66|doi=10.1086/312744|pmid=10859119|bibcode=2000ApJ...536L..63M|arxiv = astro-ph/9911445 |s2cid=27518923|display-authors=etal}}</ref> and [[Millimeter Anisotropy eXperiment IMaging Array|MAXIMA]] experiments.<ref>
{{cite journal|last=Hanany|first=S.|date=2000|title=MAXIMA-1: A Measurement of the Cosmic Microwave Background Anisotropy on Angular Scales of 10'–5°|journal=[[Astrophysical Journal]]|volume=545|issue=1|pages=L5–L9|doi=10.1086/317322|bibcode=2000ApJ...545L...5H|arxiv = astro-ph/0005123 |s2cid=119495132|display-authors=etal}}</ref> These measurements demonstrated that the [[Shape of the universe|geometry of the universe]] is approximately flat, rather than [[curved space|curved]].<ref>
{{cite journal|last=de Bernardis|first=P.|year=2000|title=A flat Universe from high-resolution maps of the cosmic microwave background radiation|journal=[[Nature (journal)|Nature]]|volume=404|pmid=10801117|issue=6781|pages=955–959|bibcode=2000Natur.404..955D|doi=10.1038/35010035|arxiv = astro-ph/0004404 |display-authors=etal|hdl=10044/1/60851|s2cid=4412370}}</ref> They ruled out [[cosmic string]]s as a major component of cosmic structure formation and suggested [[cosmic inflation]] was the right theory of structure formation.<ref>
{{cite journal|last=Pogosian|first=L.|author-link1=Levon Pogosian|year=2003|title=Observational constraints on cosmic string production during brane inflation|journal=[[Physical Review D]]|volume=68|issue=2|pages=023506|doi=10.1103/PhysRevD.68.023506|arxiv = hep-th/0304188 |bibcode = 2003PhRvD..68b3506P |display-authors=etal}}</ref>