Editing Antimatter (section)

==Origin and asymmetry==
{{see also|Baryogenesis}}

{{multiple image
|align=right
|direction=horizontal
|image2=Antimatter Explosions.ogv
|width2=232
|caption2=There are some 500 terrestrial [[gamma ray]] flashes daily. The red dots show those spotted by the [[Fermi Gamma-ray Space Telescope]] in 2010. The blue areas indicate where potential lightning can occur for terrestrial [[gamma ray]] flashes. |image1=Antimatter Explosions 2.ogv
|width1=232
|caption1=A video showing how scientists used the Fermi Gamma ray Space Telescope's gamma ray detector to uncover bursts of antimatter from thunderstorms}}

Most things observable from the Earth seem to be made of matter rather than antimatter. If antimatter-dominated regions of space existed, the gamma rays produced in annihilation reactions along the boundary between matter and antimatter regions would be detectable.<ref>{{cite journal
 |last=Sather
 |first=E.
 |date=1999
 |title=The Mystery of the Matter Asymmetry
 |url=http://www.slac.stanford.edu/pubs/beamline/26/1/26-1-sather.pdf
 |journal=[[Beam Line (journal)|Beam Line]]
 |volume=26
 |issue=1
 |page=31
 |access-date=22 June 2008
 |archive-date=12 October 2008
 |archive-url=https://web.archive.org/web/20081012012543/http://www.slac.stanford.edu/pubs/beamline/26/1/26-1-sather.pdf
 |url-status=live
 }}</ref>

Antiparticles are created everywhere in the [[universe]] where high-energy particle collisions take place. High-energy [[cosmic ray]]s striking [[Earth's atmosphere]] (or any other matter in the [[Solar System]]) produce minute quantities of antiparticles in the resulting [[particle jet]]s, which are immediately annihilated by contact with nearby matter. They may similarly be produced in regions like the [[Galactic Center|center]] of the [[Milky Way]] and other galaxies, where very energetic celestial events occur (principally the interaction of [[relativistic jet]]s with the [[interstellar medium]]). The presence of the resulting antimatter is detectable by the two [[gamma ray]]s produced every time [[positron]]s annihilate with nearby matter. The [[frequency]] and [[wavelength]] of the gamma rays indicate that each carries 511&nbsp;[[electronvolt|keV]] of energy (that is, the [[rest mass]] of an [[electron]] multiplied by ''[[speed of light|c]]''<sup>2</sup>).

Observations by the [[European Space Agency]]'s [[INTEGRAL|INTEGRAL satellite]] may explain the origin of a giant antimatter cloud surrounding the Galactic Center. The observations show that the cloud is asymmetrical and matches the pattern of [[X-ray binaries]] (binary star systems containing black holes or neutron stars), mostly on one side of the Galactic Center. While the mechanism is not fully understood, it is likely to involve the production of electron–positron pairs, as ordinary matter gains kinetic energy while falling into a [[stellar remnant]].<ref>
{{cite web
 |date=9 January 2008
 |title=Integral discovers the galaxy's antimatter cloud is lopsided
 |url=http://www.esa.int/esaCP/SEMKTX2MDAF_index_0.html
 |publisher=[[European Space Agency]]
 |access-date=24 May 2008
 |archive-url=https://web.archive.org/web/20080618215031/http://www.esa.int/esaCP/SEMKTX2MDAF_index_0.html
 |archive-date=18 June 2008
 |url-status=live
}}</ref><ref>
 {{cite journal
 |last=Weidenspointner |first=G.
 |display-authors=etal
 |date=2008
 |title=An asymmetric distribution of positrons in the Galactic disk revealed by γ-rays
 |journal=[[Nature (journal)|Nature]]
 |volume=451 |issue=7175 |pages=159–162
 |bibcode=2008Natur.451..159W
 |doi=10.1038/nature06490
 |pmid=18185581
|s2cid=4333175
 }}</ref>

Antimatter may exist in relatively large amounts in far-away galaxies due to [[cosmic inflation]] in the primordial time of the universe. Antimatter galaxies, if they exist, are expected to have the same chemistry and [[spectroscopy|absorption and emission spectra]] as normal-matter galaxies, and their [[astronomical object]]s would be observationally identical, making them difficult to distinguish.<ref>{{cite book
 |last=Close |first=F. E.
 |date=2009
 |title=Antimatter
 |page=114
 |publisher=Oxford University Press
 |isbn=978-0-19-955016-6
}}</ref> [[NASA]] is trying to determine if such galaxies exist by looking for X-ray and gamma ray signatures of annihilation events in [[colliding galaxy|colliding]] [[supercluster]]s.<ref>
{{cite web
 |date=30 October 2008
 |title=Searching for Primordial Antimatter
 |url=http://www.nasa.gov/mission_pages/chandra/news/08-160.html
 |publisher=[[NASA]]
 |access-date=18 June 2010
 |archive-url=https://web.archive.org/web/20100316213149/http://www.nasa.gov/mission_pages/chandra/news/08-160.html
 |archive-date=16 March 2010
 |url-status=live
}}</ref>

In October 2017, scientists working on the [[BASE experiment]] at [[CERN]] reported a measurement of the antiproton [[magnetic moment]] to a precision of 1.5 parts per billion.<ref name="TT-20171025">
{{cite web
 |last=Adamson |first=A.
 |date=19 October 2017
 |title=Universe Should Not Actually Exist: Big Bang Produced Equal Amounts of Matter And Antimatter
 |url=http://www.techtimes.com/articles/214821/20171025/universe-should-not-actually-exist-big-bang-produced-equal-amounts-of-matter-and-antimatter.htm
 |work=TechTimes.com
 |access-date=26 October 2017
 |archive-url=https://web.archive.org/web/20171026031017/http://www.techtimes.com/articles/214821/20171025/universe-should-not-actually-exist-big-bang-produced-equal-amounts-of-matter-and-antimatter.htm
 |archive-date=26 October 2017
 |url-status=live
}}</ref><ref name="NAT-20171020">
{{cite journal
 |last=Smorra |first=C.
 |display-authors=etal
 |date=20 October 2017
 |title=A parts-per-billion measurement of the antiproton magnetic moment
 |journal=[[Nature (journal)|Nature]]
 |volume=550 |issue=7676 |pages=371–374
 |doi=10.1038/nature24048
 |pmid=29052625
 |bibcode=2017Natur.550..371S
|doi-access=free
 }}</ref> It is consistent with the most precise measurement of the proton magnetic moment (also made by BASE in 2014), which supports the hypothesis of [[CPT symmetry]]. This measurement represents the first time that a property of antimatter is known more precisely than the equivalent property in matter.

Antimatter quantum interferometry has been first demonstrated in 2018 in the Positron Laboratory (L-NESS) of Rafael Ferragut<!--Q53261781--> in [[Como]] ([[Italy]]), by a group led by Marco Giammarchi.<ref>{{cite journal | doi = 10.1126/sciadv.aav7610 | volume=5 | title=First demonstration of antimatter wave interferometry | year=2019 | journal=Science Advances | page=eaav7610 | last1 = Sala | first1 = S. | last2 = Ariga | first2 = A. | last3 = Ereditato | first3 = A. | last4 = Ferragut | first4 = R. | last5 = Giammarchi | first5 = M. | last6 = Leone | first6 = M. | last7 = Pistillo | first7 = C. | last8 = Scampoli | first8 = P. | issue=5 | pmid = 31058223 | pmc = 6499593 | bibcode = 2019SciA....5.7610S}}</ref>