A. When the Large Hadron Collider starts running this summer near Geneva, Switzerland, some physicists have predicted that some of its high-energy proton collisions could produce microscopic black holes.

Concerned about the ramifications of such black holes, two men filed a lawsuit in March in Hawaii contending safety concerns have not been adequately addressed at the facility.

But even if miniature black holes were created — a scenario UW-Madison physicist Wesley Smith calls unlikely — they would be too weak to cause any trouble and would vanish almost immediately.

"When you try to swat a mosquito by clapping your hands together, you create more energy at that moment than we do in one collision," said Smith, who is involved in the experiments.

Since a black hole's gravitational pull is related to its energy, these hypothetical tiny objects would have too little energy to drag anything in.

In addition, he said, similar particle collisions are happening all the time in nature, as high-energy cosmic rays bombard Earth and its atmosphere. "If there were black holes being made that are dangerous to the Earth, we wouldn't be here."

Despite rigorous scientific and safety reviews, there is no evidence to suggest any cause for concern, Smith said. "It's a case of people who understand a few things about physics, but not what's really going on," he said. "None of the people who understand the physics of what's going on have any concerns whatsoever and find all this rather amusing."

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