2-1 "We are made of star stuff"

Because of the title, “We are made of star stuff,” this introduction focuses on matter. However, as Don Lincoln describes in the following video, matter really is energy, so I suppose that it does not matter. 

“We are made of star stuff” is a famous quote by Carl Sagan. You might not have heard of Carl Sagan, but he was the 20th century version of Neil Degrasse Tyson. He was extremely influential and popular in the 1970s to 1990s. He was a great scientist and science communicator. He was most well known for his popular TV series called Cosmos back in 1980. If you ask people my age who their hero is, many will say Carl Sagan. I have listened to two relatives my age speak reverently about Carl Sagan.

This chapter begins with a short review of the history of the theories of matter and energy, the discovery of the structure of the atom, and the development of the atomic bomb in World War II. In the latter half of the 20th century, scientists developed the standard model of particle physics, first based on theory, and then confirmed with experiments in supercolliders. Lastly, the chapter looks at how matter evolved in the Big Bang, the subsequent formation of larger elements in stars, and the formation of water and organic molecules in dark molecular clouds. 

History of theories of matter

People have always wondered about the origin and nature of matter (Section 2-2). For thousands of years, there was a great debate between atomists and non-atomists (Aristotelians). In the first millennium BC, Greek, Hindu, Jain, and Buddhist philosophers speculated that matter is composed of atoms. However, Aristotle rejected this concept, and his influence was so strong that atomism never gained a foothold in Europe. Most people thought that matter was composed of spirits and essences prior to the Scientific Revolution. Finally, at the beginning of the Scientific Revolution, scientists discovered elements, atoms, and molecules in experiments. These experiments led to the realization that we live in a mechanistic universe composed of atoms and molecules that are governed by physical laws and forces. 

In the 17th century, people still believed that atomism and atheism were bad and were linked. Pierre Gassendi lived at the time of Galileo and supported him and his viewpoint on the Copernican model of the solar system; however, unlike Galileo, he did not say things that offended the church hierarchy. Gassendi was the ultimate insider. He was a philosopher and scientist, and he wrote extensively on these and other topics. The Stanford Encyclopedia of Philosophy describes him as follows.

“Pierre Gassendi (b. 1592, d. 1655) was a French philosopher, scientific chronicler, observer, and experimentalist, scholar of ancient texts and debates, and active participant in contemporary deliberations of the first half of the seventeenth century.”[1]

Robert Boyle was a Protestant from England. When he was young, he went on a tour of Europe, and he visited Gassendi, among others. One might say that Boyle followed in the footsteps of Gassendi and promoted similar ideals. Although he was a Protestant, he never married. He wrote extensively on the topic of natural causes and how that viewpoint could be integrated into a conservative theological approach. Similar to Gassendi, he argued that God set up the world to operate by natural forces. He was a great scientist and made many discoveries.[2] If you are interested, the Stanford Encyclopedia discusses his contributions to philosophy.

By the end of the 19th century, scientists had conducted many experiments in chemistry and had identified many compounds, reactions, and elements. One of the most famous statements was by the great experimentalist John Dalton, “We might as well attempt to introduce a new planet into the solar system, or to annihilate one already in existence, as to create or destroy a particle of hydrogen.” He meant that it would be impossible to break apart an atom.

At the end of the 19th century and during the early 20th century, scientists discovered that atoms were divided into electrons and a nucleus and discovered many amazing facts about atoms (Section 2-3). They are governed by extremely complex, but elegant, wave equations, and quantum mechanics principles, which explain why certain chemicals react with other chemicals and the behavior of chemical reactions, as well as the interactions of atoms with such forces as electromagnetism. Scientists also learned about the energy in an atom and how to release it.

Unfortunately, people also figured out how to make nuclear weapons (Section 2-4) in the first half of the 20th century. One might say that nuclear weapons are not optimal for life. Skeptics argue that the universe is not fine-tuned for life by an intelligent being. If it were, then there would be no possibility of nuclear bombs. I don’t know whether it would be possible to not have the potential for nuclear weapons. As you will see in this chapter, atoms become more unstable as they become larger, and there is enormous energy in atoms, E = mc2. Possibly, intelligent beings, if you want to call them that, would always figure out a way to draw out the energy of the atom so that they could destroy themselves.

The Standard Model of Particle Physics

In the last half of the 20th century, scientists began to develop the Standard Model of Particle Physics. They already knew about electrons, but then they discovered that protons and neutrons each have three quarks, which are in the upper two rows. You might be interested to know that quarks move inside of protons and neutrons at 1/3 the speed of light, and electrons move inside the atom at 1% of the speed of light.  Gluons hold quarks inside of protons and neutrons like a rubber band. Protons have two up quarks and a down quark, and neutrons have two down quarks and an up quark. The force particles include gluons and photons. Gluons bind quarks together, and photons carry electromagnetic energy. The higgs boson in the upper right gives mass to other particles.

Supercolliders with particle detectors one have enabled scientists to experimentally verify the Standard Model. In supercolliders, scientists accelerate particles toward each other and crash them into each other inside of detectors. The most amazing supercollider achievement was the experimental verification of the Higgs boson. The current limitation is that supercolliders cannot simulate the hottest temperatures of the Big Bang.

Scientists have figured out how all the particles interact with each other in the current universe. For example, the W and Z bosons interact with all other particles, except the Z boson does not interact with the photon. The graviton, which is the force carrier for gravity, and which scientists have not yet discovered, interacts with all particles.

One of the most extreme examples of fine tuning in the universe is the relative magnitudes of the forces at the atomic scale. The electromagnetic force is 1/100th of the strong force, which holds nuclei together. With respect to the relative distances at which the forces interact, the electromagnetic and gravitational force extend across the universe, while the strong force and weak force are confined to the atomic nucleus. Section 2-5 describes several of these ratios and the reasons that these forces must be almost exactly as they are, including the formation of galaxies, chemical reactions. Otherwise, there would not be life in the universe.

Matter formation in the Big Bang

Section 2-6 describes the formation of matter in the Big Bang. The most significant changes in matter took place in the first microsecond. The first known matter was photons, which collided and formed gluons, quarks, electrons, and W and Z bosons within the first nanosecond, which was the quark gluon plasma.

Although the sequence of early matter formation after photons has been validated with supercollider studies, the origin of matter and dark matter is unknown. The problem is that matter and antimatter should have annihilated each other but there was an excess of matter left over, which is the current matter in the universe. The following quote is from a recent paper, which describes the problem.

“The understanding of the physical processes that lead to the origin of matter in the early Universe, creating both an excess of matter over anti-matter and a dark matter abundance that survived until the present, is one of the most fascinating challenges in modern science.” [3]

One of the most amazing examples of collaboration in the history of science is between cosmologists and particle physicists, who operate at the largest and smallest possible scales. Figure 2-19 shows the progression of temperature (T) and matter. The early universe is on the left and the current universe is on the right. The early universe was hot, thus the red color. Cosmologists can calculate the early temperature history of the universe and cosmologists can say which reactions would occur at each temperature and the phases of matter that would be stable at that temperature.

Quarks and gluons combined to form protons and neutrons during the hadron era, which took place between 1/100,000 and 1/100 seconds. In the next few minutes, about half of the hydrogen nuclei combined with neutrons and formed helium nuclei. If helium nuclei had not formed, all the neutrons would have decayed to protons. After 300,000 years, the universe cooled to the point that electrons could combine with nuclei and form atoms, as represented in this image.

Element and molecule formation in stars and dark molecular clouds.

Section 2-7 describes the fusion processes in stars (stellar nucleosynthesis) that formed the heavier elements of our solar system. The interior of stars is the perfect furnace to form the heavier elements of the universe. The extremely high density (1,000 times higher than particles on earth), temperature (14 million degrees Kelvin), and pressure (1 billion times higher than atmospheric pressure), overcomes electromagnetic repulsion and forces protons together to form heavier elements. The largest elements form in the largest stars and in supernova explosions. The sun is a third-generation star so 9 billion years of stellar nucleosynthesis produced the elements that were incorporated into the dark molecular cloud that became our solar system.

The largest element that can form in typical stellar nucleosynthesis is iron. Because iron cannot generate energy by fusion, the star implodes and forms a supernova. These exploding stars formed the heaviest elements and dust, from which our planet was constructed. Dust was also essential as the site of formation of water and organic molecules in the dark molecular cloud.  One of the essential heavier elements that formed in supernovae is uranium, as well as other radioactive elements, that melt the core of the earth and enable plate tectonics.

The solar system was born in a cluster of stars. Nearby supernovae and large stars added metals to the dark molecular cloud that formed the sun. Metals are classified as anything heavier than helium.

The sun might have been born in a section of a dark molecular cloud such as the famous picture of “the pillars of creation” in Figure 3-9 to 3-11. Large stars and supernovae have already exploded nearby, and the dust and elements from the large stars have enriched the molecular cloud. You can see stars forming in this molecular cloud, which are the red dots. These clouds are 5 light years long.

Once a dark molecular cloud forms, it protects the interior of the cloud from interior of the cloud from interstellar radiation. This enables water and organic molecules to form on the dust particles in the cloud. Prior to the formation of the sun and solar system, 50% of the solids in the cloud were water ice, 25% was dust, and 25% was organic ices. If water and organic ices had not formed in the molecular cloud, then the earth would be devoid of water and organic molecules. Otherwise, carbon, oxygen, and nitrogen would have been lost as gases to interstellar space. If one wanted to be technical about it, it would probably be more accurate to say that we are dark molecular cloud stuff rather than star stuff, since our bodies are 97% water and organic molecules.

This video https://youtu.be/NVbjOkLu2gc describes three types of fine tuning, and asks the question, Did God or natural causes finely tune the laws, constants, and initial conditions of the universe for life or was there a natural cause? 

1.     Fine tuning of the laws of nature, for example, E = mc^2 

2.     Fine tuning of the constants of nature, for example, cosmological constant 

3.     Fine tuning of the initial conditions of the universe, steady expansion 

In the following video, Don Lincoln (https://youtu.be/dC0FCUNnmDc) states that there are many examples of fine tuning in the matter of the universe. For example, protons are slightly lighter than neutrons. This causes neutrons to decay to protons in approximately 15 minutes. If the weight of protons were heavier than neutrons, then all of the protons would have decayed to neutrons in the first few minutes of the universe, and stars would not have formed. He states that one explanation for fine-tuning is design by God, but he does not consider God as a satisfying answer. He considers the multiverse hypothesis, which is that if we live in just one universe out of an infinite number of universes; thus, it is likely that in the infinite number of universes with different constants of nature, one of the universes would be likely to have the combination of the constants of nature that enable life. Dr. Lincoln states that it is a plausible philosophical concept that could be true.  

Carl Sagan believed in a scientifically based belief system, and he thought that he had disproven the validity of religion.

“Sagan expressed skepticism about conventional religion, which he wanted to replace with a scientifically based belief system.” [4]

This did not make theologians very happy, but if it is fair to use science to prove that a religion is false, then it is also fair to use science to prove that a religion is true. Why not test the creation account of Moses with scientific data. Here is the second verse in Moses’ creation account.

Genesis 2:1 The earth was formless and void, and darkness was over the surface of the deep, and the Spirit of God was moving over the surface of the waters.

In this verse, Moses stated that the earth was formless and void, which was primarily interpreted as a nebular cloud in the 19th century. Although dark molecular clouds were unknown at the time, they are almost the same as their conception of a nebular cloud. The earth existed as dust in the dark molecular cloud, which would certainly qualify as formless and void earth. There was a dark surface, which also conforms with a dark molecular cloud. There was also water in Moses’ cloud, and the solids in dark molecular clouds are 50% water ice. It was also deep, which is true about the vastness of dark molecular clouds. If the heavens and earth is the solar system, then a dark molecular cloud would be the step prior to the formation of light in the solar system, which was the sun. There is a quite remarkable agreement between a dark molecular cloud and Moses’ description of the formless and void earth in v. 2. With respect to the timing of the molecular cloud being 9 billion years after the beginning of the universe, the beginning in verse 1 can refer to a period of time so the idea that the molecular cloud formed after a 9-billion-year period of element and dust formation conforms with the meaning of v. 1.

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Carl Sagan standing with the Viking spacecraft. Credit: NASA  Public Domain

References

[1] Pierre Gassendi (Stanford Encyclopedia of Philosophy. https://plato.stanford.edu/entries/gassendi/

[2] Robert Boyle (Stanford Encyclopedia of Philosophy. https://plato.stanford.edu/entries/boyle/

[3] Di Bari, Pasquale. "On the origin of matter in the Universe." Progress in Particle and Nuclear Physics 122 (2022): 103913.

[4] Encyclopedia Britannica, Carl Sagan. https://www.britannica.com/biography/Carl-Sagan