High on the wall above the consoles and computers of the CERN control room, a blank projector screen brightened for an instant. Two small spots of light flickered suddenly in the darkness, so briefly that you could miss them by blinking.

The dozens of people crammed into the room yesterday, however, had been waiting for this moment for their entire careers. They weren’t blinking, and the place erupted into cheers and applause. After two decades of planning and construction, the Large Hadron Collider (LHC), the biggest and most expensive experiment in the history of science, was up and running.

The twin dots that appeared at 9.28am, British time, were the visual representations of two streams containing billions of protons, one of which had just been bent around a 17-mile ring at close to the speed of light by the world’s most powerful magnets. Similar beams of protons – sub-atomic particles that were forged at the dawn of time — will soon allow science to look back farther into the past than ever before, at the conditions that existed a trillionth of a second after the big bang.

The points of light left by the first protons’ lap of honour provided no scientific insights. This was more of a test run than the marathon that lies ahead. But success was essential if the LHC is shortly to start crashing these proton streams into each other, to reveal new and perhaps surprising physics.

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In the central control room, and in those that house the LHC’s four vast detectors, engineers and technicians peered at low screens, some blinking with colour and others filled with rows of monochrome data. Behind them stood many of the thousands of men and women whose brilliance has allowed this remarkable feat of science and engineering to happen, looking up at the key images projected onto the walls.

They are members of a unique community of thousands of scientists, from 85 countries, some based permanently on the industrial estate that is the CERN campus, while others dip in and out. Many have been working, eating and socialising together for a decade or more. Since 1954 the sprawling campus, where the streets bear the names of great physicists and mathematicians, has been searching for the secrets of the Universe. It now has the most sensitive tool yet built for the job.

It is hardly surprising that many could not contain their joy and relief. “Wow” was the simple response of Lyn Evans, the Welsh engineer who heads the project team, as he watched his creation leap into life. He has been instrumental in designing and building the LHC for 14 years — the machine is his professional life.

“The main feeling is overwhelming relief,” he said. “It’s a machine of enormous complexity, and things can go wrong at any time. Fortunately, this morning we have had a very, very smooth start.”

Verena Kain, a senior engineer from Austria, is a more recent recruit, but she was no less thrilled. She likened the atmosphere to mission control at Nasa’s Moon and Mars landings. “I’ve not been to a Nasa control room, but I think it’s probably exactly like that,” she said. “I still can’t believe it. I had to see it a second time and I saw that it really worked. Everybody is floating right now. I’ve had too many coffees as well, as I hardly slept last night.”

The cheering began at 8.32, when the first particles were detected snaking around the first three kilometres (1.9 miles) of the 27km (17mile) LHC ring. By 8.55, it was halfway around the track, which will soon be used to smash protons and lead ions against each other at 99.9999991 per cent of the speed of light. At 9.28, only 56 minutes after the start-up, came the champagne moment — the double trace showing that the beam had completed the first of countless trillions of laps that will explain many of the enduring mysteries of the Universe.

Once the clockwise beam was circulating, the anticlockwise stream with which it will ultimately collide was inserted in the afternoon, completing its own tour of duty soon after 2pm. Over the next few days, they will be tuned and “captured” so they fire in neat pulses. Then it will be time for business – the collisions that will generate new physics.

By recreating the environment of the dawn of time, the LHC will detect phenomena that have never before been observed. It should find the Higgs boson, the so-called “God particle” that theory suggests gives matter its mass, but which has never been found. It should also determine whether all particles have a twin, as a theory known as “supersymmetry” suggests, and thus explain the mysterious “dark matter” that pervades the Universe, but which cannot be seen.

The LHC may even find new dimensions, beyond the three of space and one of time with which we are familiar. It promises to unlock great secrets of the cosmos.

“Particle physics is a modern name for the centuries-old effort to understand the laws of nature,” said Professor Tejinder Virdee, who heads the Compact Muon Solenoid detector team. “Humankind has an unquenchable thirst for knowledge and understanding the surroundings in which we live.

“The excitement is of having completed a machine that’s taken 20 years to plan and build. Now we’re looking forward to the really interesting part: even more excitement awaits us as we start doing the science. The LHC is going to look deeper into matter and go back further in time than we’ve been able to go before. It’s the most powerful microscope ever built and at the same time the most powerful telescope ever built.

“We have these theories, and now we’re getting into new territory to put them to the test. We don’t know what we’re going to find – that’s why we do the experiments.”

The first trial collisions, from which researchers will calibrate their detectors, could start as early as next week. The LHC will then start operating at about 70 per cent of maximum energy, before it is ramped up to full power next year. Discoveries about supersymmetry could come quickly, but the hunt for the Higgs boson will take longer, with few results expected before 2010.

For Dr Evans, 63, from Aberdare, yesterday’s achievement was “a great relief”, the culmination of 14 years of work on the collider, and the harbinger of a happy retirement. “Over the next year and a half I hope to bring the LHC up to its maximum potential, and then I’ll go off and play golf,” he said. He also won a bet with a colleague, who doubted that the first beam would be running in as little as an hour.

Also celebrating was someone at the other end of a scientific career: Kate McAlpine, 23, who has found unlikely online fame with the “Large Hadron Rap”. Her rhyme about the LHC has been downloaded almost two million times from YouTube, and has been praised for introducing a new audience to particle physics.

Ms McAlpine, from Lowell, Michi-gan, watched in the Atlas detector’s control room as the first beam of particles travelled through. “When the yellow and green line appeared snaking through Atlas, it was a pretty exciting place to be,” she told The Times. “I’m just amazed they pulled it all off in an hour.

“The most exciting thing for me would be finding extra dimensions, though antimatter is a close second. We see space, and it seems so obvious that there are three dimensions, but if we can find proof that others are there it would be mind-blowing.”

Thinking big

The 1,000 Genomes Project An international project to map the most common human genome variants. This detailed analysis of the make-up of human genetics will allow scientists to spot DNA variations between humans that allow susceptibility to disease

The Boulby Mine Experiment Running since 1987 more than a kilometre below the Yorkshire moors. Scientists are attempting to beat CERN in finding the elusive “dark matter” that theoretically makes up over 40 per cent of the Universe’s mass

LIGO American-led project that seeks to find the “gravitational waves” that were first theorised by Albert Einstein in 1916. The project is attempting to detect ripples in space-time by measuring the exact patterns of laser refractions between mirrors

Phoenix Mars Lander launched in August last year, arriving on Mars in May, below. The 18ft vehicle is designed to scour the surface of the planet looking for carbon-based chemicals, water and raw materials. The correct combination of these would offer hope of life on Mars

COROT is a telescope launched into the Earth’s orbit by a French-led scientific consortium. Its purpose is to seek out Earth-like planets beyond our solar system. Using a series of complex measuring functions, the telescope is able to assess the habitability of any planet it finds

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