Why Trees Break Physics: Feynman Explains the 33-Foot Water Paradox & Redwood Secrets #Physics #RedwoodTrees #ScienceExplained #NatureFacts
Pull all the air out of a pipe standing in water, and the water climbs until it hits a wall it can't get past. That wall is about 33 feet. Even with a perfect vacuum, it stops there. But there's a redwood in northern California that's about 380 feet tall and gets water all the way to the top.
So either that tree is cheating physics, or your idea of how trees drink is wrong. Physics is fine; your answer in your head is broken. The real answer has water doing something you'd swear water can't do.
Here's the answer you're walking around with: the roots suck the water up. That's the whole theory, and you've never once checked it. So let's check it, starting with the word suck, because nothing in physics sucks. When you drink through a straw, all your mouth does is lower the air pressure inside. The air outside, pressing down on the surface of your drink, shoves it up to you. That air is pressing on you right now. The whole atmosphere, about 14.7 pounds on every square inch of you, and that push is the only thing doing the lifting.
And the push has a ceiling. Take every bit of air out of the pipe and you've used up everything the atmosphere has to give. The water rises until the weight of the column matches the push of the air, and at sea level that happens at roughly 10 meters, or 33 feet. Past that, there's no push left.
People found this out the hard way. In 1638, Galileo published Two New Sciences, and one of its characters describes a water pump that stopped working. The workman said no pump of that kind could raise water more than 18 cubits (around 10 meters). The explanation in Galileo's book was that the column of water snaps under its own weight like a rope that's too long. Hold onto that rope, by the way. It's coming back because that explanation was wrong.
In 1644, Evangelista Torricelli wrote that we live submerged at the bottom of an ocean of air. Air has weight, and that weight is what holds the water up. Run out of it, and the water stops.
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