At a purpose-built underground centre by CERN near Geneva, Switzerland, the scientists are carrying out limited tests on a multi-million euro machine called the Large Hadron Collider.
The ultimate aim is to recreate conditions that existed immediately after the Big Bang.
The team hopes to pinpoint dark matter, the name given to unseen particles thought to exist all around us and throughout space.
The experiment, which began at 8 am this morning Irish time, involves smashing protons - one of the building blocks of matter - into each other at velocities only a fraction less than the speed of light.
In the flashes from the collisions, scientists expect to reproduce conditions that existed during the first billionth of a second after the Big Bang at the birth of the universe.
Large Hadron ColliderDetails on the on-going experiments will be posted very soon.
