Faster Than Light Signaling Made Easy

When I was getting my undergraduate degree at Ohio State University, physics and math classes took up a lot of my time. But when preposterous claims were brought to our attention, me and my friends always seemed to find time to check them out. Two such claims stand out in my memory. The first was a curious explanation for why trees can grow taller than 30 ft. If trees raise water by pulling a vacuum by evaporating water from their leaves, then atmospheric pressure (15 lbs/square inch) is insufficient to push a column of water higher than thirty feet. Yet outside my door there are redwoods effortlessly growing to five times that height. The explanation offered to "explain trees" was that thin water columns could support "negative" pressure and hence surpass the "natural limit to growth". This could be checked by trying to lift a mercury column to a greater height than 760 mm by placing water on top of the mercury and evaporating it thru a sintered-glass funnel. We had all these thing in the physics lab, so a few of us built an "artificial tree" and were surprised to see that after a few days of evaporization, the mercury column was indeed much higher than the "natural limit" suggested by  naive arguments based on air pressure.