Originally Posted by wphamilton

Nope. I know how to disregard the more trivial possibilities, and the more likely possibilities that make a more trivial difference.

A black hole may whiz by at exactly the wrong time for example, yanking the cyclist into the ground. I don't "know" that this won't happen. But I DO know that it isn't important. Similarly, a vehicle might strike the cyclist in just such a way that he's somersaulting, head driven to the ground at significantly greater speed. I don't "know" that it won't happen. But I know that it's a more trivial possibility.