The Problem With the Cosmological Constant

The cosmological constant has the special property that it is small, but if it were bigger, we wouldn't be here to talk about it. So therefore, if you have a multiverse with different values of thecosmological constant, you can account for its smallness by saying that we only see those regions in which the value is small. This was argued by Linde and Weinberg and others all the way back in the 80s. The best idea we have right now is the anthropic principle - there are small numbers in physics.