The proton–proton chain reaction is one of two nuclear fusion reactions, along with the CNO cycle, by which stars convert hydrogen to helium and which dominates in stars the size of the Sun or smaller.
In general, proton–proton fusion can occur only if the kinetic energy (i.e. temperature) of the protons is high enough to overcome their mutual electrostatic or Coulomb repulsion.
In the Sun, deuterium-producing events are rare as diprotons, the much more common result of nuclear reactions within the star, immediately decay back into two protons. A complete conversion of the hydrogen in the solar core is calculated to take more than (ten billion) years. 1010
The theory that proton–proton reactions are the basic principle by which the Sun and other stars burn was advocated by Arthur Stanley Eddington in the 1920s. At the time, the temperature of the Sun was considered too low to overcome the Coulomb barrier. After the development of quantum mechanics, it was discovered that tunneling of the wavefunctions of the protons through the repulsive barrier allows for fusion at a lower temperature than the classical prediction.
Wer sht dann, dat ich dich noch vermess un
Ich hing nur noch vr der Kess?Nchtelang, dat ess wirklich nit wohr.
N, em hnz, ich saach et dir, hhr mir joot zo:
Aff un zo sinn andre Fraue do, aff un zo.
Jo, ich kumme schon kloor.
Joot, ich drink jetz'e paar Droppe mieh,
Doch, wat soll't et deit ech nit mieh wieh.
Hann die janze Buud renoviert, woot och Zigg un ich saach et dir:
Htt sich rentiert, he ess nix mieh, wat zo dunn htt met dir, nur om
Flur dat verstemmte Klavier.
Ahnunfrsich denk ich kaum noch ahn dich,
Jarkei Problem ich hann alles om Schirm.
Ahnunfrsich denk ich kauf noch ahn dich,
Ahnunfrsich.
Joot, ich hann lnger nit opjerhmp
Un dat Leejut knnt och weg, stemmp.
Vver nit, dat mer he nix mieh fingk,
Fing och nit, dat die Sphlmaschin
Noh Mllmmer stink
Un d Lou Reed noh Beerdijung klingk.
Wat wei ich, wovun d'm Augebleck singk!?
Nobby sht, et jv ene Typ,
Wo mer dich neuerdings off met sieht.
Denk jetz nit, dat mir dat ir'ndjet mht.
Jedenfalls, wenn d lppsch weed, roof ahn, saach
Mer Bescheid. Ich kumm jhn ens koot me'm Hammer vorbei un bring ihm