Scientists involved in a historic "Big Bang" experiment hope that it will turn up many surprises about the universe and its origins -- but reject suggestions it will bring the end of the world.
And Robert Aymar, the French physicist who heads the CERN research centre, predicted that discoveries to emerge from his organisation's 6.4 billion euro ($9.2 billion) project would spark major advances for human society.
"If some of what we expect to find does not turn up, and things we did not foresee do, that will be even more stimulating because it means that we understand less than we thought about nature," said British physicist Brian Cox.
"What I would like to see is the unexpected," said Gerardus t'Hooft of the University of Michigan. Perhaps, he suggested, the Large Hardron Collider (LHC) machine at the heart of the experiment "will show us things we didn't know existed."
Once it starts up on Wednesday, scientists plan to smash particle beams together at close to the speed of light inside CERN's tightly-sealed Large Hadron Collider to create multiple mini-versions of the primeval Big Bang.
Cosmologists say that that explosion of an object the size of a small coin occurred about 13.7 billion years ago and led to formation of stars, planets -- and eventually to life on earth.
A key aim of the CERN experiment is to find the "Higgs boson," named after Scottish physicist Peter Higgs who in 1964 pointed to such a particle as the force that gave mass to matter and made the universe possible.
But other mysteries of physics and cosmology -- supersymmetry, dark matter and dark energy among them -- are at the focus of experiments in the 27-km (17-mile) circular tunnel deep underneath the Swiss-French border.
FEARS OF DISASTER
CERN, the European Centre for Nuclear Research, says its key researchers -- and many ordinary staff -- have been inundated by e-mails voicing fears about the experiment.
There have been claims that it will create "black holes" of intensive gravity sucking in CERN, Europe and perhaps the whole planet, or that it will open the way for beings from another universe to invade through a "worm hole" in space-time.
But a safety review by scientists at CERN and in the United States and Russia, issued at the weekend, rejected the prospect of such outcomes.
"The LHC will enable us to study in detail what nature is doing all around us," Aymar, who has led CERN for five years, said in response to that review. "The LHC is safe, and any suggestion that it might present a risk is pure fiction."
Cox, from the School of Physics and Astronomy at Britain's Manchester University, was even more trenchant. "I am immensely irritated by the conspiracy theorists who spread this nonsense around," he said.
When the experiment begins soon after 9 am (0700 GMT) on September 10, disaster scenarists will have little to work on.
In the first tests, a particle beam will be shot all the way around the LHC channel in just one direction. If all goes well, collisions might be tried within the coming weeks, but at low intensity. Any bangs at this stage, said one CERN researcher, "will be little ones."