Sorry I'm slightly late with this. I got caught up in writing this evening, so I took advantage of my new DVR and recorded the show to watch an hour or so later. Having a DVR is pretty cool. Bubble Trouble: An interesting one, but rather simple to cover. The myth is that you can't swim in bubbly water because the lower density makes you sink. All three phases of the test were basically variations on the same principle -- you got the bubbles, but they pushed the swimmer up rather than making him sink. And it's interesting how that works. It goes to show the dangers of not considering all the aspects of a process. If you just think about the interaction of the bubbly water and the swimmer, the logic seems simple -- aeration of the water means the water's density is lower, and all else being equal, a lower-density medium creates less buoyancy. But the key factor being overlooked there is the interaction of the bubbly water with the water around it. Since the aerated water has lower density than the water around it, its own buoyancy increases, causing it to rise and create a convection current. So rather than sinking, the swimmer is pushed up. So it was that overly narrow focus on the interaction between swimmer and aerated water that overlooks the consequences of how the aerated water interacts with its larger context. I'm not sure if there's a way around that, a way to get all the water in the tank or pool equally less dense so that there's no convection. Maybe some kind of laminar airflow, the entire bottom surface of the pool emitting gazillions of teeny bubbles so there's no room for any denser water to sink. Probably all but unattainable in practice. But I have to say, Jamie's canvas-bag bubble generator was a great idea. As they said on The Middleman, his plan was sheer elegance in its simplicity (and he's not even a supervillain -- that we know of). I'm surprised that the big upright tank they erected for the whirlpool myth has apparently just been sitting there at Alameda for years. I wonder, did they keep it because they figured they might need to reuse it sometime, or was it just too much trouble to take it down? Dynamite Arrow: Okay, this was kind of a silly myth -- that you could shoot an arrow with a stick of dynamite on it into a tree and cause it to split vertically in two. Maybe it sounds a bit plausible at first, but as they showed, it really doesn't hold together. Heck, as soon as I saw that first arrow sticking into the log, I realized, "Hey, that explosive is too far away from the tree to blow it apart -- it'd have to be actually inside." I realized that even before anything actually exploded. Still, I expected it to take a bigger chunk out of the tree trunk, and I expected that last set of six sticks to simply shatter it. Instead, the trunk was barely harmed. Which is really impressive. But then, come to think of it, it's logical that a tree could cope with something like that. It's a force hitting the trunk face-on from the side -- not unlike the force exerted by a gust of wind. (Yes, it's pressure instead of wind motion, but in terms of the direction and spread of the force, it's analogous.) And trees are evolved to cope with wind, or they wouldn't survive long. What alarmed me about those bomb-range scenes was that shot of that herd of cows going by in the background. They were startlingly close to the explosives. I thought bomb ranges were supposed to be far away from anything living. In the final test, I liked the way they went against the usual "bigger boom" approach and tried for as precise, minimal, and surgical a use of explosives as they could manage. It's intriguing how precisely explosives can be directed and calibrated to perform specific tasks, and that reality stands in stark contrast to the myth that you can just throw dynamite at something and get a specific result. Even so, the mythical split was not in evidence. (In the aftershow on the website, they explained that they used the bare minimum amount of ANFO explosive that would even detonate at all. Which leads to the question if there's an even gentler explosive that could've been tried.) Assuming the person who suggested the myth wasn't just making it up, or outright lied to by the father who told the story, I wonder if maybe it was just misunderstood -- maybe the story was that the tree was split in two horizontally, like the test trees. Or maybe it was something that only happened once -- the dynamite arrow happened to penetrate an already-existing crack in a dead tree. Or maybe it was some other one-in-a-million freak occurrence. More likely that it was about as legitimate as the viral videos they test.