Why micro black holes might be safe, but I am not relaxed and comfortable yet

LiveScience.com - Despite Rumors, Black Hole Factory Will Not Destroy Earth

Greg Landsberg, a physicist who actually did bother corresponding with James Blodgett (who runs the "Risk Evaluation Forum" that got me interested in possible danger from micro black holes) gives this recent explanation as to why he thinks any MBH created at CERN will not be any danger to the Earth:

"Still, let's assume that even if Hawking is a genius, he's wrong, and that such black holes are more stable," Landsberg said. Nearly all of the black holes will be traveling fast enough from the accelerator to escape Earth's gravity. "Even if you produced 10 million black holes a year, only 10 would basically get trapped, orbiting around its center," Landsberg said.

However, such trapped black holes are so tiny, they could pass through a block of iron the distance from the Earth to the Moon and not hit anything. They would each take about 100 hours to gobble up one proton.

At that rate, even if one did not take into account the fact that each black hole would slow down every time it gobbled up a proton, and thus suck down matter at an even slower rate, "about 100 protons would be destroyed every year by such a black hole, so it would take much more than the age of universe to destroy even one milligram of Earth material," Landsberg concluded. "It's quite hard to destroy the Earth."

These figures sound good, but I tend to worry that they may be made on a set of expected results (regarding, for example, the number that would have earth escaping velocity, the exact dimensions and behaviour of MBH, the conditions inside the Earth where the slow ones stay, and possible interactions with each other) which are far from worst possible estimates.

Given that its the fate of the earth at issue, it seems to me that some calculations should be done on worst case scenarios to be confident of the outcome.

I suppose it is possible that Landsberg has done that, but I am somewhat suspicious that he hasn't. After all, he really believes there is no reason to doubt Hawking Radiation will take care of the problem, so this further exercise is perhaps done on the basis that you don't really have to take it too seriously.

One thing I also don't understand is why it takes an estimated 100 hours for a MBH to absorb a proton.

Maybe it irritates physicists to have a lay person doubting their figures, but I feel it is worth pressing on with the issue none the less.

The fact that there is a lot of uncertainty about the expected precise behaviour of MBH can easily be seen by the number of papers that show up on an arxiv search for "black holes".