Tonight Matthew, we're going to talk about trees, fences (specifically iron ones) and walls. How come when a tree grows near a wall/fence/combination of the two, it can deform the structure? The answer must lie in the laws of physics; otherwise ghosts exist, and Mercury Retrograde is a thing to be scared of.
The last time I was sent out of class was in 1984. It was physics with Mr Taylor, and Mr Taylor's teaching method was thus:
"Read pages 67-72 of your text book, and write out what you think it all means. I'll be watching the girls play hockey out of the window."
Okay, he didn't actually say the last bit, but it's what happened every lesson. There were 25-30 budding scientists in that "lab" my friends, and who knows how many of them would've turned out the finished genius if the "lab" hadn't looked out onto the girl's hockey pitch (or Operation Yewtree had been about).
Anyway, one bit in the text book said that if you lean against a wall, then according to Newton's Third Law (which states that for every action there is an equal and opposite reaction), the wall is pushing you back with equal force. This, of course, is bollocks.
Yes, blah blah blah Newton, indeed blah blah blah Third Law, but the wall is just a structure. It's there, it was built, it's been left, it doesn't fight back.
I argued this with Mr Taylor, but the girls must have been playing a particularly vigorous game of hockey that afternoon, so he was in no mood to argue and sent me out. If he'd at any point said that the laws of physics are unarguable I might've shut up, but he just pointed at the bit in the book saying the wall was pushing me back as hard as I was pushing it. Which, of course, was bollocks.
On my walks around the streets of cinema's own London town, there are a few examples of trees that have, over their hundred or so years of growth, deformed walls and fences that once contained them. When I see this I think: "wow that's weird, a plant made of living and dead cells is able to knock a wall down." But I also think: "that seems about right, a plant made of living and dead cells is able to knock a wall down." I don't have a problem with it happening, but I'm not sure if Newton's Third Law can explain why it happens.
First, some other things that happen with trees and walls (which are more explainable):
Sometimes trees fall onto walls. I've seen the aftermath of this, and it's pretty one-sided. A mature London Plane tree is too heavy for just about any wall to resist. Where's the equal and opposite reaction here? I'm guessing the answer is that if the wall was of equal size/weight/strength to the tree, it would be able to push back said tree. The speed of the tree falling must also multiply its weight, I assume. But this still assumes the wall wants to push back the tree.
Back to a tree slowly growing towards a wall...
The tree is made up of living cells in its middle, dead cells on the outside, and can grow roughly an inch wider every year. When the tree reaches the wall, why doesn't nature 'tell' it the wall is too hard to grow through? Every year another inch of live cells have been produced inside the tree, but these cells are not tougher than a brick wall. Neither are the dead cells on the outside. It's possible to remove bark from the outside of trees with your hands, for instance. Yet together, this minute movement of living and dead cells is somehow able to completely destroy a wall over time.
My one attempt at an explanation: imagine a tube of toothpaste (it isn't hard to do). When the tube is full the toothpaste comes out with force, but with minimal effort from you. When the tube is half full, the toothpaste comes out less forcibly, or you have to put more effort in. However, if you curl up the bottom of the tube to half-way, you can recreate the original force of a full tube, because it's "full' where the toothpaste comes out. Imagine a tree is a tube of toothpaste (it isn't hard to do). The live cells are constantly growing, and adding "toothpaste" to the tube, but there's no cap to remove and let the toothpaste out. So the tube gets bigger, is always full, and is always at full strength. Strong enough to knock down a wall, anyway.
I asked Robin Ince of 'The Infinite Monkey Cage' if he or science dreamboat Brian Cox could help shed some light on this. Perhaps there is a sub-law of physics that explains this phenomenon. Perhaps no explanation is needed. Perhaps it's all down to ghosts.
He 'liked' my tweet, but no reply has come. I put this down to the following possible reasons:
It's a stupid question; if I'm sensible and adapt the laws of physics properly, it can easily be explained.
He asked big Bri C the question, and because Coxy couldn't come up with an answer, they've fallen out and BC has joined a religious cult.
He couldn't be arsed.
Listen and read Proff C prove ghosts don't exist here:
https://www.independent.co.uk/news/science/ghosts-brian-cox-large-hadron-collider-cern-real-truth-standard-model-physics-a7598026.html
Captains log, star date: supplementary...
We have an answer: THE WIND. The tree gets close enough to the fence for its movement in the wind to act on the fence. Tall buildings move in the wind, which is a bit scary but happens nonetheless, and so do trees once they're tall enough. So it's as if the tree has fallen onto the fence, but very slowly.
