Editing Antihydrogen (section)

==Characteristics==
The [[CPT theorem]] of particle physics predicts antihydrogen atoms have many of the characteristics regular hydrogen has; i.e. the same [[mass]], [[magnetic moment]], and atomic state transition frequencies (see ''[[atomic spectroscopy]]'').<ref>{{cite magazine|url=http://focus.aps.org/story/v26/st1 |title=The Coolest Antiprotons |magazine=Physical Review Focus |author=Grossman, Lisa |date=July 2, 2010|volume=26|issue= 1}}</ref> For example, excited antihydrogen atoms are expected to glow the same color as regular hydrogen. Antihydrogen atoms should be [[gravitational interaction of antimatter|attracted to other matter or antimatter gravitationally]] with a force of the same magnitude that ordinary hydrogen atoms experience.<ref name=natrev/> This would not be true if antimatter has negative [[gravitational mass]], which is considered highly unlikely, though not yet empirically disproven (see ''[[gravitational interaction of antimatter]]'').<ref>{{cite magazine|url=http://www.technologyreview.com/view/423901/antihydrogen-trapped-for-1000-seconds|date=May 2, 2011|title=Antihydrogen trapped for a thousand seconds|magazine=Technology Review|access-date=March 18, 2014|archive-date=April 14, 2015|archive-url=https://web.archive.org/web/20150414171504/http://www.technologyreview.com/view/423901/antihydrogen-trapped-for-1000-seconds/|url-status=dead}}</ref> Recent theoretical framework for negative mass and repulsive gravity (antigravity) between matter and antimatter has been developed, and the theory is compatible with CPT theorem.<ref>{{Cite web|last=Du|first=Hong|title=Application of New Relativistic Quantum Wave Equation on Hydrogen Atom and its Implications on Antimatter Gravitational Experiments|url=https://www.researchgate.net/publication/344381683|url-status=live|archive-url=https://web.archive.org/web/20210426065717/https://www.researchgate.net/publication/344381683_Application_of_New_Relativistic_Quantum_Wave_Equation_on_Hydrogen_Atom_and_its_Implications_on_Antimatter_Gravitational_Experiments |archive-date=2021-04-26 }}</ref>

When antihydrogen comes into contact with ordinary matter, its constituents quickly [[Annihilation|annihilate]]. The positron annihilates with an electron to produce [[gamma ray]]s. The antiproton, on the other hand, is made up of antiquarks that combine with quarks in either neutrons or protons, resulting in high-energy [[pion]]s, that quickly decay into [[muon]]s, [[neutrino]]s, [[positron]]s, and [[electron]]s. If antihydrogen atoms were suspended in a [[Free space|perfect vacuum]], they should survive indefinitely.

As an anti-element, it is expected to have exactly the same properties as hydrogen.<ref>{{cite news|url=https://www.bbc.co.uk/news/science-environment-17284822|title=Antihydrogen undergoes its first-ever measurement|first=Jason|last=Palmer|work=BBC News |date=14 March 2012}}</ref> For example, antihydrogen would be a gas under standard conditions and combine with antioxygen to form antiwater, {{physics particle|anti=yes|H}}<sub>2</sub>{{physics particle|anti=yes|O}}.