Heavy Ion Collisions to Go Back in Time In the Big-Bang theory,our universe is in expansion since Hydrogen atom Protogalaxy 15 billions of years. Helium atom Only ultra- relativistic heavy ion collisions THE BIG BANG THEORY could allow to recreate a small TIME ONE PRESENT BEGINS SECOND DAY volume of nuclear Time 10-435c 10-325eC 10-6 sec. 3 min. 300.000y5 billion yrs. 15 billion yrs. matter such as the 1027c 1013c 108C 10.000c -200℃ 270°c one having existed The cosmos Post-inflation. goes through 3Cooig 486ag combine with yrage As galaxies cluster asuoerlasl 边a'cothing cosmos permits atoms,charged protons and heltum gas Ingether uader in the first micro "inflation." not soup or quarks to electrons and neutrons to form coalesce to【orm gravity,the first expanding from eleetrons. clump into protons prevent atoms.mostly the giant clouds stars die and spow seconds of our hes1 ze of a月 quarks and protons and ight from hydrogen and that will become heavy clements gtom to that o neutrons shining:the helium.Light galaxlos:smaller into space:these particies universe is a can finally clumps of gas will eventually universe,the Quark superhot fog shine collapse to form form into new the first stars stars and plangts Gluon Plasma (QGP),making then possible the study and the evolution of this phase of matter. 2023/6/28 Talk for EM group伍健 32023/6/28 Talk for EM group 伍健 3 Heavy Ion Collisions to Go Back in Time In the Big-Bang theory, our universe is in expansion since 15 billions of years. Only ultra￾relativistic heavy ion collisions could allow to recreate a small volume of nuclear matter such as the one having existed in the first micro seconds of our universe, the Quark Gluon Plasma (QGP) , making then possible the study and the evolution of this phase of matter