One thing glossed over: Joe mentions that the muons are undergoing time dilation by some factor, which allows a fraction of them to live long enough to reach earth, but in their own frame their clocks run normally. How can that work? The missing piece is that the muons see their travel as length contracted by the same factor. They don’t decay because they didn’t travel very far, (or for very long) as seen in their frame.

The link to make a cloud chamber