The following is based on part ten of Jacob Bronowski’s BBC series on the history of science and invention, “The Ascent of Man” (1973). This one is about the atom:
Dmitri Mendeleev played a game his friends called Patience: he wrote the chemical elements down on cards, one element on each card along with its atomic weight, and laid out the cards in different ways.
He found that if he laid the cards in order of atomic weight and yet put elements with like properties in the same rows, he could create a table – what we now call the periodic table of elements. He found that he could tell which elements had yet to be discovered and what their properties would be.
But what makes such a table possible? Why do properties repeat so that you can make rows in the first place? How can the different properties of an element, like density and colour, come from just a single property, atomic weight? The answer is: they cannot. Atoms must have more than just weight. Atoms must be made of parts.
In 1897 J.J. Thomson found the first part: the electron. In 1911 Ernest Rutherford said the atom is like a little solar system: the electrons go round the nucleus just like the planets go round the sun.
But Niels Bohr in 1913 saw that it could not be that simple: the planets are slowly running down and some day will fall into the sun. Not so with atoms. Bohr found the answer in Max Planck’s idea of quantum energy: just like matter comes in atoms, so energy comes in quanta. Therefore the electron can only be at certain energy levels or orbits. .
But what about the nucleus that the electrons were circling? That proved to be made of parts too: protons and neutrons, as James Chadwick found out in 1932.
All this, along with Einstein’s physics, made it possible in 1939 for Hans Bethe to work out how the sun shines. It does it by making two hydrogen atoms into one helium atom and, in the process, changing the left over matter into heat and light. The sun is a young star, but older and larger stars, it was soon understood, turn helium into the other elements: carbon, oxygen, iron, gold and all the rest.
The stars evolve hydrogen into the elements while the earth evolves the elements into life. That is how nature works: one small step at a time.
That seems to go against entropy – the idea that the universe is running down, becoming more disordered over time. But entropy is a statistical observation. That means by and large it holds true, but it does not always hold true.
Ludwig Boltzmann gave us our idea of entropy. He also championed the idea that matter is made of atoms. We take it for granted – partly because of him – but in 1906 there were still plenty of doubters. In despair, just before his side was about to win, he killed himself.
See also:
- Jacob Bronowski: The Ladder of Creation – part nine
- Jacob Bronowski: The Majestic Clockwork – Newton and Einstein
- Jacob Bronowski: The Hidden Structure – chemistry and atomic theory
Abagond 
There is a place that astronomy, geology, natural history and biology converge. You start looking around your room at the walls, the carpet, the computer, the glass your drinking from, everything and say, “wow, all the elements that make up this stuff in my room came from a cloud of gas many billions of years ago when an ancient supernova exploded in this part of the galaxy. What was left over is what we see when we look at anything, even our own bodies. We are literally made of left over star matter than somehow that over billions of years became self-aware. It’s mind-blowing when you start thinking about it, and how we got to so much complexity from just two primordial elements in the universe, helium and hydrogen.
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this reminded me with a BBC documentary I’ve lately seen, it missed all my knowledge up. check it up, it is really interesting.
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Michio Kaku, the Japanese guy in the video is quite interesting to listen to. I’ve heard him interviewed on the radio a number of times. He usually is pretty good at making complex scientific principles simple to understand for laymen. However, I don’t think anybody that has ever explained what the hell string theory is in any way that makes sense to the common person. I don’t get it.
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In despair, just before his side was about to win, he killed himself.
What?!? I had no idea about this. How sad.
The sun is a young star, but older and larger stars, it was soon understood, turn helium into the other elements: carbon, oxygen, iron, gold and all the rest.
I just want to add that, according to theories, not all stars can create all elements. You need a supernova to create particularly heavy elements. You can’t create heavy metals without supernova. The heaviest element ordinary star can make is iron. Anything heavier than that requires supernova.
I do believe another physical process for creating heavy metals has been discovered in the past few years, but we still don’t know much about it. In any case, supernova explosion is still the only known source of creating all isotopes of heavy metals, and the principle source of all heavy metals in universe.
Which basically means that any heavy element found on Earth was once part of supernova. Including elements in our own bodies.
@tulio
However, I don’t think anybody that has ever explained what the hell string theory is in any way that makes sense to the common person. I don’t get it.
String theory is un-explainable. :p Just kidding. I think I understand the principle behind it, but it’s really difficult to imagine strings theory universe, because, well- we can’t think in more than 3 dimensions.
Plus, unlike some complicated astronomical objects which can actually be explained in two or three clear sentences (black holes, for example), I don’t really think it’s possible to explain strings theory without specific scientific vocabulary. I think.
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Mira said:
“Which basically means that any heavy element found on Earth was once part of supernova. Including elements in our own bodies.”
I think that is so cool and so wanted to point it out, but Bronowski did not so I did not. It was hard!
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Well, it does sound amazing. And it’s perfectly natural.
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@tulio &Mira
trust me, you will get more confused when you see the whole program, the string theory will be M (membrane) theory and the 3D will be 11D! then what mira said will be somehow true.
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