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Where does a tree get its mass?

thelastpsychiatrist.com

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Re: Where does a tree get its mass?

#21

Post by ErrantX »

radu_floricica wrote: post #13
ErrantX wrote: post #7

Excellent. After the first line I deliberately closed my eyes and tried to re-reason it (and got it right, thankfully). It was quite refreshing to have a blog post make you actually stop and really think for a second. The point was good as well. ;)

It's the whole blog, not just the post :) Really worth bookmarking.

Damn straight. I just finished reading one of his latest entries; acidic, critical and brilliant IMO.

http://thelastpsychiatrist.com/2010/06/are_certain_behaviors...

EDIT: money quote: The science error of our generation is this: If A is strongly associated with B, and B is strongly associated with C, then A is strongly associated to C.

Re: Where does a tree get its mass?

#22

Post by djacobs »

ErrantX wrote: post #19
djacobs wrote: post #18

As far as I know, most of the CO2 in plants goes to respiration for energy production. Not saying it doesn't go to mass, as well, but it's the energy side of things that people learn in elementary school. We're not stupid, and this man needs to think about his accusations before he blogs about them...

In defence I don't read his points as being "you're stupid" but more about the fact that we don't think about what we are talking about. The Ask question... wrong! thing strikes me as simply a device to make this point.

I don't think his premise is true. He says we were all taught photosynthesis in elementary and high schools and now all we know is a phrase that has no meaning for us. In fact, no one teaches the whole story of anything in biology before college, and not everyone takes college bio. Those of us that did knew the answer. It's a question of how far into biology you've studied...

Re: Where does a tree get its mass?

#23

Post by jules »

ckuehne wrote: post #17
chaosmachine wrote: post #12

Feynman knows: http://www.youtube.com/watch?v=N1pIYI5JQLE

Can't upvote you enough for this. By the way, Feynman also knows the difference "between knowing the name of something and knowing something": http://www.youtube.com/watch?v=05WS0WN7zMQ

This. He really articulates clearly the difference between two ways of thinking. Thinking by really understanding then translating the thoughts into words and thinking by manipulating words.

Re: Where does a tree get its mass?

#25

Post by djacobs »

JabavuAdams wrote: post #16
superkarn wrote: post #10

The analogy at the end (section IV) made the whole article easier to "get". ...an answer cannot be more precise than its data. Or its question.

Except the example he gave was also wrong. 3 + 4.2 is 7.2, using exact arithmetic, which should be the default assumption. If you're measuring values under uncertainty, then his explanation makes some sense. But that's a property of measurement and uncertainty, not of numbers or arithmetic.

Hear, hear. A voice of reason. This blog entry is the perfect example of where knowing a little information is dangerous.

Re: Where does a tree get its mass?

#27

Post by kragen »

Retric wrote: post #4

This forget's about all the H as a tree get's most of it's hydrogen from water. EX:"Glucose" (C6H12O6) is from 6 * H20 + 6 * C02 => C6H12O6 + 6 * O2. So a reasonable ansewer would be mostly air and water with some minirals from the soil.

Glucose, which is pretty similar to cellulose in composition, does indeed contain two hydrogens and an oxygen for each carbon. But the carbon has a mass of 12 AMU, the oxygen of 16, and the two hydrogens total 2 together. So 6⅔% of the cellulose is hydrogen by weight, and the other 93⅓% is carbon monoxide.

(I have no idea whether the oxygen atoms from the water end up in the glucose or in the excreted O₂.)

Re: Where does a tree get its mass?

#28

Post by samatman »

JabavuAdams wrote: post #16
superkarn wrote: post #10

The analogy at the end (section IV) made the whole article easier to "get". ...an answer cannot be more precise than its data. Or its question.

Except the example he gave was also wrong. 3 + 4.2 is 7.2, using exact arithmetic, which should be the default assumption. If you're measuring values under uncertainty, then his explanation makes some sense. But that's a property of measurement and uncertainty, not of numbers or arithmetic.

Default assumption for whom?

For a scientist, or someone working with real world data, this should never be the default assumption.

Besides, in the paragraph with the arithmetic he explicitly talks about significant figures. In context, the answer is unambiguously 7 .

Re: Where does a tree get its mass?

#29

Post by scrod »

ckuehne wrote: post #17
chaosmachine wrote: post #12

Feynman knows: http://www.youtube.com/watch?v=N1pIYI5JQLE

Can't upvote you enough for this. By the way, Feynman also knows the difference "between knowing the name of something and knowing something": http://www.youtube.com/watch?v=05WS0WN7zMQ

While we're talking about Feynman, I think most people here could relate to his perspective on uninterrupted time, and the avoidance of administrative work: http://www.youtube.com/watch?v=Y08g3OXAA14&NR=1

Re: Where does a tree get its mass?

#30

Post by Tichy »

stupid mode

Opens up more questions than it answers. It seems when trees die, they become earth or even oil. How come they don't completely dissolve into air again? And if they don't completely dissolve into air, how come all the CO2 is not bound in the earth yet (trees pluck it out of the air, then die and bind it to the ground)? There would have to be bacteria or something that converts soil into air (CO2), but then, why don't they dissolve everything?

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