Scientists recreate conditions at dawn of universe
Researchers working at the Large Hadron Collider in Geneva have produced a primordial state of matter not seen since the beginning of the universe.
Just weeks after the world's largest particle accelerator began smashing together heavy lead ions to create little Big Bangs, the experiment has produced a primordial state of matter akin to what existed at the dawn of the universe.
The Large Hadron Collider (LHC), a 17-mile-long (27 kilometer) underground ring run by the European Organization for Nuclear Research (CERN) near Geneva, began colliding lead ions together Nov. 8. These atomic nuclei contain 82 protons, and are much heavier than the lone protons the accelerator was previously colliding.
Now two experiments at the LHC – called ATLAS and CMS, respectively – have reported a phenomenon called "jet quenching" that scientists say could reveal secrets about the nature of matter and the evolution of the universe.
After two ions crash into each other, detectors measure jets of particles that emerge from the high-energy collision. Jets are formed as the basic constituents of nuclear matter, called quarks and gluons, fly away from the collision point.
In proton collisions, jets usually appear in pairs, emerging back to back. However, in the tumultuous conditions created by heavy ion collisions such as those made by lead nuclei, the jets interact with a hot dense medium created when temperatures are so high that the basic constituents of matter break apart.