The Big Bang was a huge explosion of energy. Some of it condensed into matter. That set the universe in motion. It led to the formation of atoms. It also led to the formation of galaxies, stars, and planets.
Physics is the study of matter and energy. Atomic physics leads directly into chemistry. Electrons are attracted to the nuclei of atoms. What happens because of that?
That sets the stage for the evolution of life on Earth. How did chemistry create biochemistry?
ACT I
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The universe began with an extremely dense concentration of energy. Then it exploded in the Big Bang, kind of like a gigantic supernova.
Physicists have hypothesized what existed before the Big Bang and how that led to the Big Bang. But none of that matters to our story of how physics affects us in everyday life here on Earth.
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The Big Bang is where Change = Motion began.
The energy started moving outward from that point of origin. As it did it began cooling off. Some of it turned into subatomic particles, called quarks. Quarks are basically droplets of solidified energy.
There are two forces in the universe. That means the universe has two properties that make Change = Motion happen. One is gravity. The other has a really weird name. Because over the years scientists discovered different manifestations of it and called it different things before they realized it was all the same thing.
That’s called electro-stong-weak force. Electro is an abbreviation of electromagnetism, which refers to two other ways people discovered the same things.
Electromagnetism is the force that attracts electrons to the nuclei of atoms. That’s the force that makes electricity and magnetism happen, and also the force that powers chemical reactions, including fire and the digestion of food.
Weak force is the force that binds protons and neutrons together into the nuclei of atoms. Strong force is the force that binds quarks together to form protons and neutrons. (Electrons don’t have strong force bonds because they’re individual quarks.)
ACT II
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Soon after the Big Bang gravity began drawing quarks together. The quarks attracted each other, kind of like magnets. When they connected they created protons and neutrons, and were held together by strong force bonds.
Gravity kept pulling protons, neutrons, and electrons together. Now protons and neutrons attracted each other. Many of them connected with each other, and were held together by weak force bonds.
Some protons formed pairs, and a few formed groups of three, while many others didn’t connect with other protons. Many of those groups of one, two, or three protons also connected with one, two, three, or four neutrons.
Some didn’t connect with any neutrons. That created the nuclei of hydrogen, helium, and lithium atoms, the first three elements in the Periodic Table of the Elements.
Those nuclei attracted electrons. When they connected they formed electromagnetic bonds. Now they were atoms.
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Gravity was still pulling things together. Now these atoms were forming clouds. We can call them gas clouds. Because hydrogen and helium are gases all the way down to extremely cold temperatures.
Outer space is cold enough to make helium condense into a liquid and to make hydrogen freeze solid. Lithium is a metal that doesn’t melt until 357 degrees Fahrenheit. So even though these weren’t actually clouds of gas, helium only has to warm up about 2 degrees Celsius above the temperature of outer space, and hydrogen about 18 degrees, to turn into gas, and then they’d be clouds of gas with a little bit of lithium dust in them.
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Now something new was happening.
Since everything was moving outward from the Big Bang, but gravity was drawing things toward each other, that made everything move outward and sideways at the same time. That made these clouds rotate.
The force of gravity increases with mass. The bigger the clouds got, the more atoms they attracted. Also, the bigger the clouds got the more gravity drew atoms together in the centers. The denser they became in their centers, the more gravity increased, and the more atoms they drew into their centers.
When enough atoms accumulated in the centers of the clouds the force of gravity became so strong that it started tearing the nuclei of atoms apart. That broke the weak force bonds, and released a lot of energy.
That started a new reaction. The energy that was released from the weak force bonds being broken turned into heat that pushed the atoms apart. Now two forms of Change = Motion created Balance = Stability.
Gravity pulled the atoms together and broke their nuclei at the same rate that the heat from the weak force pushed the atoms apart. That created a stable reaction. That’s what a star is.
Now you can see the point of calling these gas clouds. When the stars formed and started giving off heat, they could heat up the hydrogen and helium around them enough to turn them into gas.
The first stars didn’t have planets, because there was nothing in their clouds that could form planets. Long before frozen hydrogen could gather into a ball the size of a planet, the star would heat it up 18 degrees and turn it into a gas.
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With all that gravity inside the stars, many protons and neutrons were getting crushed together and forming bigger nuclei. That created the nuclei of all the elements up to iron, with 26 protons.
Eventually a star breaks so many weak force bonds there aren’t enough left to keep the reaction stable anymore. Then gravity overpowers the heat from the weak force and the star collapses. Gravity draws the particles in the star together until the star becomes so dense and its gravity becomes so strong that it starts breaking the strong force bonds in the protons and neutrons and breaking them up into quarks. That releases the strong force energy. Then one of three things happens.
The simple one is that the heat from the strong force balances against gravity and the star stabilizes again. That’s what a dwarf star is.
If the star collapses too quickly to stabilize into a dwarf star, it breaks so many strong bonds at once that it explodes. That’s what a supernova is.
Sometimes the outside of the star collapses first and explodes in a supernova. The explosion blows the center of the star inwards. Then gravity has overpowered everything else. Then you have the remains of a star crushed together with hardly any bonds left to break and hardly any energy left to give off. Then you have a star with a massive amount of gravity that doesn’t give off light. In fact, its force of gravity is so strong it sucks light in from outside. That’s what a black hole is.
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When the stars exploded in supernovas, some of that energy drove protons and neutrons together into bigger groups. That formed the nuclei of the rest of the atoms on the Periodic Table of the Elements.
The process repeated. Gravity drew the atoms together into new rotating clouds. But this time there were much bigger atoms in those clouds. These were clouds of gas and dust.
Gravity drew the atoms inward and new stars formed in the centers of the clouds. But this time the dust further out in the cloud drew together to form solid objects: Planets, moons, asteroids, and comets.
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Steven Hawking connected the stories of cosmology and particle physics in his book A Brief History of Time, in 1988. I’m sure other people have written other books about it since then that are easier to read.
ACT III
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The Periodic Table of the Elements carries the story of atoms into chemistry. It was first compiled in 1869 by a Russian chemist named Dmitri Mendeleev. It was a chart of all the elemental chemicals that chemists had discovered to that point.
Chemicals like hydrogen, helium, carbon, nitrogen, oxygen, iron, and copper could be combined into other chemicals but couldn’t be broken down into other chemicals. No matter what reactions chemists put those chemicals through, or what new chemicals they produced, they could always perform another chemical reaction on the new chemicals and get those original chemicals back.
The properties of the elements were discovered through a lot of experimentation. Those were a lot of clues that led to the discovery of atoms.
The properties of elements are first principles of chemistry. This is Constant = Constant. We don’t know why they exist, and we may never know, but we do know that no alternatives have been discovered. We keep using this information and keep getting reliable results, even if we don’t know why this information is reliable.
What is it about protons, neutrons, and electrons that makes carbon, an atom with 6 protons and electrons a solid at room temperature, but oxygen, an atom with 8 protons and electrons a gas?
Iron has 26 protons and electrons, and copper has 29, so why does that make iron so much harder than copper?
Those are the kinds of questions either nobody knows the answers to, or the answers are so complicated hardly anyone cares.
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Chemical reactions don’t affect the nuclei of atoms. They shift electrons around among atoms. The chemical bonds in a molecule are made by multiple atomic nuclei attracting the same electrons. Chemical reactions shift electrons around, so the attraction between electrons and multiple nuclei creates different connections among atoms.
Electrons shifting from atom to atom is also what creates electricity. That means that every chemical reaction has an electrical current.
Electricity is the same thing as magnetism. That means every chemical reaction also has a magnetic field.
Generators produce electricity with magnets. Batteries produce electricity with chemical reactions.
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This story of physics and chemistry tells us two important things.
First, life evolved on Earth from a chemical reaction that was started by geology.
Second, chemical reactions producing electrical currents eventually led to the evolution of brains.