> In turn, most rain comes from water evaporated from surface water
This is true over the whole Earth, but if you look only on land (which is what matters in this case) roughly 80% of rainfall comes from plant transpiration, not evaporation from open bodies of water.
I... had never put together that this is probably part of why plants took a (long!) while to colonize land. Between that and there not being a soil-ecology yet, yeah, that paints the picture pretty completely.
"The knowledge that the atoms that comprise life on earth - the atoms that make up the human body, are traceable to the crucibles that cooked light elements into heavy elements in their core under extreme temperatures and pressures. These stars- the high mass ones among them- went unstable in their later years- they collapsed and then exploded- scattering their enriched guts across the galaxy- guts made of carbon, nitrogen, oxygen, and all the fundamental ingredients of life itself. These ingredients become part of gas clouds that condense, collapse, form the next generation of solar systems- stars with orbiting planets. And those planets now have the ingredients for life itself. So that when I look up at the night sky, and I know that yes we are part of this universe, we are in this universe, but perhaps more important than both of those facts is that the universe is in us. When I reflect on that fact, I look up- many people feel small, cause their small and the universe is big. But I feel big because my atoms came from those stars."
And this can be taken a little further. That we humans are the only part of the universe, as far as we can tell at least, to be aware of all this. We are the part of the universe that allows it to look back at itself. If the universe is a body, we are the eyes of that body. Generally speaking of course. But I find this very empowering as a human being.
Possibly not the same particles, though. Baryonic matter condenses and undergoes nuclear transformations in the stars. But if our feelings and memories are electrical phenomenon then they were not formed in stars.
I think electrical activity in the brain is misunderstood. These electrical signals are not electrons moving along a wire, they are waves of depolarisation between the inside and inside of the cell membrane travelling along the axon or dendrites. The depolarisation is due to the activity of a bunch of ion pumps and channels that let ions pass between the inside and outside of the cell. Some of these ion channels are themselves voltage-gated, thereby further increasing the depolarisation in response to depolarisation, and propagating the signal that way.
So it's still mostly atoms moving in and out of cells. Still stardust.
Obviously, the patterns weren’t formed in stars. My point is, if you are admiring the body being a pattern formed of particles coming from the stars, realize that the admiration is itself also just such a pattern (as is that realization).
The elemental atoms ultimately came from the inside of the stars.
Hydrogen was created shortly after the Big Bang when the universe had expanded far enough to cool down that protons and electrons could come together to form hydrogens.
Hydrogens come together later to form the stars. Nuclear fusion inside the stars starts due to the pressure from gravity. Nuclear fusion of hydrogens turns them into heliums.
When the hydrogens at the core of the star are used up, the star collapses and then explodes, throwing the upper crust off.
At the core nuclear fusion of heliums starts, forming lithiums. Nuclear fusion of lithium then forms beryllium. The cycles of nuclear fusion of each element type continue to create the heavier and heavier elements. Carbons are created among the way. So is oxygen.
During each cycle the star explodes and throws off the elements from the upper crust.
After iron is created, nuclear fusion stops. Iron is super stable to resist nuclear fusion. Gravity continues to collapse the star until super nova happens.
Super nova is when all the other heavier elements created. Gold, silver, lead, platinum, uranium and others are created during this explosion.
The elements come together to form the planets and eventually become part of us. So we were created long ago inside a star.
It's the electromagnetic force of their 26 electrons that pushes two iron atoms apart such that the gravitational force of the star cannot overcome.
Nuclear fusion happens when two atoms come close enough that their strong nuclear force binds them together. Strong nuclear force only has effect in very short distance at the nuclear. Smaller atoms with their smaller size allow gravity of the star to push them together for fusion to happen. Bigger atoms with their more numerous electrons make it more difficult.
Bigger stars with stronger gravity can force fusions all the way to iron. Although iron resists fusion, a worse fate awaits it. With no more fusion, the star collapses further and becomes much hotter. The iron nuclei are broken down into alpha particles. The electrons and protons combine to form neutrons, releasing a flood of neutrinos, which cause supernova. Supernova has enough strength to cause fusions of all the heavier elements.
Actually I missed one crucial detail. Not just the electrons of the atoms are repelling each other, the positively charged protons of the atoms are repelling each atom as well, even more so. As the protons are tightly packed in the nucleus, it's even more difficult to force the nucleus of two atoms together.
Most interesting parts of this article for me: most of the organisms weight in carbon and other atoms comes from and get recycled into the air, and, most atoms in our body replace every few weeks, we are just "patterns surviving through time".
This seems to be a very big difference with non-organic things, including computers, which even though they are coming pretty close to thinking with LLMs now, keep the same atoms in the same configuration all the time.
"To throw around some numbers: about 220 petagrams (gigatonnes) of carbon dioxide will be released into the atmosphere this year; around 3% from burning fossil fuels; 44% from the ocean surface; and 53% from the land"
Does the 3% from burning fossil fuels seem too low? I thought that this would make up the majority of carbon dioxide released into the atmosphere every year
You’re confusing net and gross carbon release. In a balanced system, on average 100% of released carbon will be reabsorbed, by rocks, oceans, and (to a fairly small extent) plants, making the net rate of change of atmospheric carbon practically zero. Then humans began to meddle with things, starting to introduce extra carbon to the atmosphere from outside the primary carbon cycles. Carbon fixing rate has also increased to compensate (leading to further problems like acidification of the oceans) but has not been able to keep up, especially because the excess anthropogenic release rate has been growing exponentially. Thus the net release rate has been slightly above zero for the past 200+ years, and it’s starting to show.
This was a fascinating read. One other interesting fact about the carbon in our bodies is that the sort of diet that a person eats over their lifetime can influence the ratio of the different isotopes of carbon in their body due to different plants preferentially using carbon 12 or carbon 13 during photosynthesis. You really are what you eat.
What a fantastically written article! I was familiar with all of this (or almost all; I was not aware that fossil fuel burningakes up a measly 3% of yearly atmospheric carbon emissions) but there's a difference between knowing the information and seeing it explained so prosaically.
> In any case: to me, the picture this paints is one in which we are not so much solid, isolated objects; and more like patterns surviving through time.
Something I have struggled to find nearly as much material on is where our _molecules_ come from. I know of lots of ways in which they're formed, but things like, are there any molecules in stars? How much? How much are they distributed in the universe? How complex and large do molecules get in the universe?
I'm especially interested in the proto-life molecules. How close do we get to e.g. proteins without having life?
> about half your nitrogen atoms were being stripped from the air in some great metallic reactor like the one pictured
I’d never appreciated before how much nitrogen was taken from the air to support agriculture. I wonder if this has a direct impact on climate change. Does reducing nitrogen in the air necessarily increase the proportion of the other gases including carbon dioxide?
for effectively everyone who has ever lived, and even most living adults, your body contains at least one atom that has been part of them, such as air they breathed or water they drank.
So if plants are roughly half carbon half water, and the carbon comes from the air while the water comes from the ground, it makes sense that plants spread roughly symmetrically both below the ground and above the ground. Well, a bit more above the ground because they also need photons.
There is a tendency to draw the silhouette of a tree with roots the same size as the canopy but this image is wrong. The root system of most plants run much shallower than people assume because there is no oxygen in deep soil to sustain the roots. A 300 feet giant Sequoia would only reach 12 to 15 feet into the ground.
(You have the perfect username to be talking about trees)
I was shocked by the shallowness of a sequoia root system (though have never thought of any roots being as deep as their tree is tall!). It feels like the centre of mass would be too high for stability.
The trick is the width of the root system, especially plate roots, which can be over 40X the width of the trunk, and can interlock with neighbouring trees forming a stablising matrix.
There are almost fully underground trees which allows them to survive fire (they just lose the photosynthesising top) and also survive where grasslands have driven out forest cover. I know these trees exist in Africa, but don’t know if they live elsewhere.
I would think of these as “bushes” but really there’s no difference between a shrub and a tree except in the eye of the beholder.
Yes, sequoia are lucky to be able to rely on each other for support. There are many species of trees are technically capable of growing to hundreds of feet tall but they are invariably lost to strong wind and lightning strikes long before that point.
Sequoia is a special case though. They can afford to be so shallow because the live in families, and all the roots in the forest intertwine and they help each other stay upright. Other forests are not that intertwined.
I only knew about that rule (mirror the branches) when it comes to oaks in particular. Other trees have evolved differently: palms will dig for water deep down for example.
A tree is a slow-motion explosion, one which can only occur at the boundary (interface) between air and earth.
A human is a slow-motion explosion, one which can only occur at the boundary (interface) between fluid and uterine wall.
We're not so different, because physics doesn't change. Both systems need resources from both sides in order to grow, so an interface is really the only option.
I was hoping there is some interesting concept behind your comment. It’s not quite obvious in which sense exactly you would be seeing a human as an explosion.
The word choice of "explosion" is only mildly interesting IMO, and only because it emphasizes that trees and people can be (often more accurately) thought of as events instead of as things.
For me, the more interesting / relevant part (and the reason I brought it up in the first place) is the "interface" aspect.
I, likewise, hope there's "some interesting concept" behind your comments too. I can only presume you'll offer a highly stimulating intellectual payoff for answering your highly tedious questions. :-D
https://www.nature.com/articles/nature11983