Experts say it is the largest scientific experiment in human history and the Large Hadron Collider (LHC) is the biggest and most complex machine ever made.
The test by the European Organisation for Nuclear Research (CERN), conducted inside the tightly-sealed chamber buried under the Swiss-French border, could unlock many secrets of modern physics and answer questions about the universe and its origins.
The 10 billion Swiss franc ($9 billion) machine’s debut came as a blip on a screen in the control room, with a particle beam the size of a human hair appearing in the 27-km (17-mile) circular tunnel.
"We’ve got a beam on the LHC," project leader Lyn Evans told his colleagues, who burst into applause at the news.
The several hundred physicists and technicians huddled in the control room celebrated loudly again when a particle beam made a full counter-clockwise trajectory of the accelerator, successfully completing the machine’s first major task.
"It is going fantastically well," said Verena Kain, a senior engineer in charge of the control room.
Scientists will later on Wednesday send another beam around the chamber clockwise to ensure the path is clear.
Scientists around the world are eagerly anticipating data on those minuscule crashes. One possibility is that they will cause the creation of matter — proving correct the theory that there exists a "Higgs Boson" that gives matter its mass.
The elusive Higgs Boson is a theoretical particle, also known as a "God particle", and is named after Scottish physicist Peter Higgs, who first postulated in 1964 that it must exist.
Doomsday writers have also fanned fears that the experiment could create anti-matter, or black holes, spurring unprecedented public interest in particle physics ahead of the machine’s start-up. CERN has insisted that such concerns are unfounded.