So how does a siphon really work?
A local physicist in Australia claims to have corrected a very old error in the Oxford Dictionary which apparently states a siphon works on atmospheric pressure. Not so, he says, gravity is what powers a siphon. This raised some disagreements, so maybe you smart Pruners can offer some thoughts?
My own thought is imagine running a siphon in a large chamber and steadily evacuating it (to remove the atmosphere). At some point the water will vapour lock in the siphon, will it not? Is there a "perfect fluid" that could be used instead? Intuitively, a siphon would not work in weightless environment as there is no difference between the upper and lower reservoir (QED?)
So my money says that it needs gravity to move the fluid and pressure is needed to keep it fluid. Any offers?