Quarks are believed to have formed very shortly after the Big Bang. The precise timeline is still a subject of ongoing research and study, but our current understanding suggests that quarks emerged within the first microseconds (10^(-6) seconds) after the Big Bang.
During the early stages of the universe, the temperature and energy density were extremely high. At these extreme conditions, the fundamental forces and particles were unified into a single, highly energetic state. As the universe expanded and cooled, it underwent a phase transition called the "quark epoch."
During the quark epoch, the energy of the universe dropped below a critical threshold, allowing quarks to exist freely instead of being confined within other particles. This phase transition led to the formation of a quark-gluon plasma (QGP), which is a state of matter where quarks and gluons are not confined within individual particles but are instead deconfined and behave collectively.
The quark epoch is believed to have occurred within the first microseconds after the Big Bang when the universe was incredibly hot, with temperatures around several trillion degrees Celsius. During this time, quarks and gluons roamed freely, interacting strongly with each other.
As the universe continued to expand and cool, the temperature dropped further, leading to the confinement of quarks within hadrons (particles like protons and neutrons) due to the strong force. This confinement marked the end of the quark epoch and the beginning of the hadron epoch.
Although we cannot directly observe the quark epoch, experiments conducted at high-energy particle accelerators, such as the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), aim to recreate and study the properties of the quark-gluon plasma. By studying the behavior of matter under such extreme conditions, scientists gain insights into the early universe and the formation of quarks.