Why do fluorescent tubes explode if broken (is it the compression of the gas)?
Fluorescent tubes operate at very low pressure; roughly 1/1000th of an atmosphere. They do not explode when broken; they implode. The atmospheric pressure surrounding the tube crushes it as soon as it begins to crack. The tube shape of a typical fluorescent tube is chosen because it can withstand the enormous compressive forces of the atmosphere better than most other shapes.