The discussion centers on the pressure conditions in a closed tank and the implications of atmospheric pressure at two points within the system. Participants question the author's assertion that P1 and P2 equal atmospheric pressure, arguing that the tank is closed and not open to the atmosphere. It is clarified that both points are not sealed and are open to the atmosphere through their filling apertures, allowing for atmospheric pressure to be present. The conversation highlights the importance of understanding how the siphon hose interacts with the tank openings, which are not airtight. Ultimately, the lack of a seal means that the pressures can be considered atmospheric under the given conditions.
