Straight from the first paragraph of the Hypotheses section, emphasis mine. >Also called Chimney effect or Stack effect, observes that warm air (from the hot s

Straight from the first paragraph of the Hypotheses section, emphasis mine. >Also called Chimney effect or Stack effect, observes that warm air (from the hot shower) rises out over the shower curtain as cooler air (near the floor) pushes in under the curtain to replace the rising air. By pushing the curtain in towards the shower, the (short range) vortex and Coandă effects become more significant. However, the shower-curtain effect persists when cold water is used, implying that this cannot be the only mechanism at work. Scientists investigate and prove things that are "common sense" things all the time because the "common sense" answer turns out to be wrong.