Originally posted by: Gaffer Tape
In the Zahn trilogy, Luke theorizes that a "dark Jedi" lived in that cave before Yoda arrived, and, upon arriving, Yoda killed him. But the existence of a strong presence of both the light and dark side of the force neutralized each other, thus making it a perfect hiding place from the Empire, and it also explains why Luke wasn't able to sense Yoda.
In the Zahn trilogy, Luke theorizes that a "dark Jedi" lived in that cave before Yoda arrived, and, upon arriving, Yoda killed him. But the existence of a strong presence of both the light and dark side of the force neutralized each other, thus making it a perfect hiding place from the Empire, and it also explains why Luke wasn't able to sense Yoda.
That's exactly the explanation. Though I'll admit I don't know how Kenobi stayed hidden...