41–50 of 61 posts
Feynman knows: http://www.youtube.com/watch?v=N1pIYI5JQLE
"He was just a curious kid in a grown up's body."
You've only got to watch Feynman's face as he's telling the story, or any story for that matter. His excitement and enthusiasm for the curiosities of life is infectious.
Feynman knows: http://www.youtube.com/watch?v=N1pIYI5JQLE
Earlier quoted context omitted.
If the meant "50% of the mass of some trees is from water" that then he should have said so. Some trees are more than 50% water by mass is a true statement, but it means something else. The author saying something related to the truth, but I think he has a poor understanding of what is going on. Reading that I felt like a teacher who wants to give some created for a student using the correct words while realizing the…
> As to precision it's more accurate to say 3 +/- 0.5 times 101 +/- 0.5 = 256.25 to 355.25 or 305.75 +/- 49.5 than to just say 300. Ah, problem is you've changed the question now. Which is a reasonable thing to do when face with 3 + 101.5 = ?, but not the point the author was making (or, actually, it is the exact point the author is making) :)
His explanation in terms of addition is incomplete. Since "3" only has one significant digit (3.03.0 is a more precise number with 2 significant digits) the answer itself can have no more than one significant figure. 3 +/- .5 + 101.5 +/- .05 = 104.5 +/- 0.55 which has 2 significant digits. Now in his example 3 + 4.7 the three does limit the question to 1 significant digit, but your example has more than that even though your also adding 3 to a number (104.5 +/- 0.55)
PS: This is all assuming the accuracy based on the number of digits given you could easily have 3 +/- .0001 and 101.5 +/- 70.
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...
Are you aware that cellulose is just interlinked glucose molecules? A tree is basically a giant hunk of hydrated sugar byproducts with some minor mineral and other components.
Some observations: Polysaccharides are not sugars. Mono- and di-saccharides made of carbohydrates are. Glucose has other uses than becoming cellulose or starch or glycogen. The life cycle of a plant is not linear or simplistic. CO2 is not only used as a substrate in anabolism.
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...
And what does a tree do with this energy? It's not a light bulb. It uses the energy to split the oxygen off of the CO2, splits the oxygen of off water, and makes hydrocarbons from the C in CO2 and the H in water. The oxygen is released as waste (a small amount is used). So all the energy used in a tree is devoted to making its mass.
However he's talking mass and reneges on his statement that trees are made from the air by stating that many trees are over 50% water. Well IMO when talking about mass the majority-share counts as the subjects mass origins.
The plant breaks down CO2 into C + O2 via photosynthesis. The C makes up the plant. This is the simplified version he starts with, which was an ample metaphor. However then he states that the tree can be predominantly water. Meaning the plant is made up of say 60% water and 40% carbon.
However the plant is made up of predominantly of water trapped within cellulose membranes. If we talk dry weight, we're still talking 6 carbon atoms (72), 10 hydrogen atoms (10) and 5 oxygen atoms (80). This means roughly 66% of the trees mass comes directly from water from the ground sequestered in its cellulose.
This means roughly only 20% of the tree actually comes directly from carbon sequestered from the air.
So really, where does the plant get its mass? The ground.
If you're asking where the plant gets its dry weight, still the ground by ~6%.
By tackling a logical fallacy with scientific thinking he opened the window to be completely corrected by it himself. Trees grow because they take the carbon out of the air. However you talk about mass and we're talking about molecular weights.
Now if he'd have been as smart of Feynman he would have dismissed the water quite logically again. The rain falls from the sky. Save for a few very large trees that actually reach into the water table, trees well inland rely solely on the rain for their supply of water. That means the 50% of its mass that is water still technically comes from the air from moisture being condensed in cold air and forming water droplets.
Feynman knows: http://www.youtube.com/watch?v=N1pIYI5JQLE
Bob: That's easy, Eli Whitney
Adam: What's a cotton gin?
Bob: Shrug
Did anyone else think this was going to be about the Higgs boson?