Natural Units –
atoms, molecules, moles, and electrons The fundamental components of materials are called
the natural units.
In order to talk about the nature of the In this Chapter, we explore the material world. Unlike universe ... I shall take the simple minded
the elusive energy, a material has a mass and occupies a view that a theory is just a model of the
volume. Thus, we can easily recognize a piece of universe, or a restricted part of it, and a set of
rules that relate quantities in the model to material. Driven by energy, materials undergo constant
observation that we make. It exists in our changes, generating all kinds of phenomena. Natural minds. units participate in these changes, but they themselves Stephen W. Hawking remain the same. A Brief History of Time
Unlike physical and chemical phenomena that involve
large quantities of material, nuclear phenomena usually
deal with interactions among natural units. Thus, we shall review the investigations on natural units before we introduce any nuclear phenomena.
? What are natural units?
? How many kinds of natural units are there?
? How do natural units make up the material world around us?
? Have we found the true natural units of the material world?
The spirit of science, including nuclear science, is to dig for the ultimate truth. Looking for the ultimate fundamental natural units of the material world started with philosophical approaches followed by scientific investigations. The digging has gone on for almost 5 thousand years, and the dig continues. Quickly, we review the philosophical approaches and experiments leading to the discovery of chemical elements, atoms, molecules, moles, and electrons in the past. The search for natural units had a slow start, but the results grow exponentially. Following the discovery of radioactive decay, experiments have revealed not only the structure of atom but also smaller sub-atomic particles such as electrons, protons and neutrons. We accepted them as fundamental natural units of matter for a while, but further investigations revealed that protons and neutrons are composed of several particles. These will be discussed in future chapters. Whether we have found the ultimate natural units remains to be seen, and I hope you keep a continuous interest on this topic to see its future development.
Philosophical Approaches on the Fundamental Natural Unit of Materials
Ancient people did not have the energy concept, nor did they understand the material world. They did not have concepts to perceive deeper into the material world than what it appeared to their eyes. To them, wood logs burned and disappeared, leaving nothing but a little ash behind. Soil, rock, clay, and sand appeared to be indestructible by fire. Water came from the darkened sky and caused floods and mudslides that kill.
However, some wise men asked fundamental questions and suggested that there are some fundamental components for the material world. Their suggestions were accepted on faith rather than on reason or comprehension.
Philosophical approaches from Oriental and Hellenistic cultures on the fundamental components material are briefly described here. People in the orient believed in the dualism of Yin and Yang whereas Plato proposed the primal substances.
Natural Units of Dualism All materials ultimately originated from the
two forces Yin (? ? and Yang (--). DifferentWith a history of more than 5000 years, the proportions of Yin and Yang made eachChinese culture is wide spread, particularly in the material unique.orient.
? What is the ancient Chinese view of the
One of the Chinese classics called I-Ching
dominated the ancient Chinese view of the
material world. A translation of it is known as Book
of Change, which was written during the Chu
dynasty (1134-247 BC), in cryptic language, which
is used by most fortunetellers as their folly.
However, it also has its academic value as a classic.
A dominant symbol in the book, the Ultimate (Tai-
chi) and the trigrams, is shown here. The Ultimate The symbol for Tai-chi, and the tri-grams in
consists of Yin and Yang, from which everything is the Book of Change.
derived. Yang is the cosmic male principle and Yin is the cosmic female principle.
Yin and Yang were the suggested natural units of all materials. Yang is represented by a solid
line –– whereas Yin by a broken line - -. Combining equal portions of Yang and Yin results in
four things. Fu-Hsi showed the formation of eight things when they are divided in three parts each can be Yin or Yang, and he represented them by the tri-grams. When a whole has many parts of Yin and Yang many more things are generated. When a whole has many parts of Yin
and Yang more things are generated. Thus, natural units Yin and Yang are the fundamental
building blocks of materials.
The dualism of Yin-Yang represents a view of the world that does not distinguish energy from matter. This view still affects the ways many Chinese think, eat, exercise, and live. For discussion:
1. What are Yin and Yang?
How can combinations of them generate so many different things or material? 2. What phenomena cannot be explained by the Yin and Yang dualism?
Plato’s Natural Units
Plato and Aristotle left their postulates regarding the material world in writing. They had no
concept of energy, and their postulates did not differentiate matter from energy, like the dualism of Yin and Yang. Their intellectual exercises qualitatively described the changing world, and they dominated the reasoning process for a long time.
? What are the natural units proposed by Plato?
Plato (427-347 BC) postulated that combinations of four primal substances: air, water, fire, and
earth made up all materials. Plato hinted at the fifth unobservable substance, ether or quintessence,
but it was not widely known. Thus, he suggested four or five natural units. In his Timaeus, Plato associated the regular
polyhedra with the primal substances: cube
with earth, tetrahedron with fire, octahedron
with air, icosahedron with water, and
dodecahedron with ether. From a
EarthWatergeometrical viewpoint, there are five and
only five regular polyhedra. He thought
these mathematical forms are the ultimate FireAir
representation of the world. This postulate
connected geometrical results with the
physical world, a system uniting the
(Ether)(mathematical) minds and the material
world. Polyhedra have definite shapes. Size
and quantity concepts were not present The five regular (platonic) solids, four of whichduring his time. had been associated with the primal substance.
Plato's student Aristotle (384-322 BC) Earth Water examined the ideas of primal substances from the
viewpoint of causes and effects. He believed in Cold
having a limited number of primal materia, but Dry Wet added four qualities: hot, cold, wet, and dry. In
his mind, a combination of these qualities and Hot
primal substances caused all the phenomena of
Fire Air the world. The primal materia are connected to
the qualities in Aristotle's world, as shown in a
diagram here. Little further development was Four primal substances and four qualities in Aristotle's
material world. made regarding his qualities in terms of science.
Plato applied his knowledge in geometry to
interpret the physical world. Aristotle (Sarton, 1970) took it a step further to explain the changes. These early developments illustrated human desire to know the natural units of the material world.
Plato's doctrine influenced scientific reasoning for almost two thousand years. For example, Angelo Sala (1575-1640) considered fermentation as a regrouping of the primal substance. Daniel
Sennert (1572-1627) postulated four kinds of atoms (a concept not of finite size) corresponding
to the four primal substances. Few scholares challenged Plato's doctrine until it failed to explain the existence of various kinds of air.
During the period between the 5th and 3rd centuries BC, theories of nature in India and other parts of the world were based on conceptions of materials called fire, wind, water, earth, space,
and vitalism (animated atoms). The dualism of love and hate also played a part. However, water, fire, wind and earth were considered as natural units in many cultures, perhaps originated from Plato.
Skill developing problems:
1. What are the natural units postulated by Plato? How are the primal substances related to modern concept
of materials? Give a modern definition to primal substances? (Hint: Some scholars suggested the
primal substances were related to solid, liquid, gas, and plasma state of material. A fire is a
plasma as we shall see in the chapter on nuclear fusion.)
2. Describe Aristotle’s material world. How are Aristotle’s qualities related to the modern scientific concepts?
Chemical Elements and Atoms
After the time of Plato and Aristotle, human activities became more and more complicated. Enterprises of alchemists, medicine men, and technologists flourished. Due to their wealth, these people had the leisure to pursue scientific reasoning. Slowly, people acquired the concept of quantity and size through commerce, before they acquired the energy concept. Attitudes of philosophers began to change. Plato and Aristotle still had influence but they no longer dominated the academic circle. For example, Francis Bacon (1561-1626) introduced methods of fact collection and deduction. R. Descartes (1596-1650) introduced a principle of doubt, accepting nothing that cannot be clearly established to be true. Galileo (1564-1642) invented experimental methods, and other scholars soon use them.
thThe attitude change in the 16 century made a huge difference in the study of the material
world. Technologies such as air pump were available to study air. Various gases were identified, and natural units primal substances is replaced by chemical elements
Gas Identification and Boyle's Concept of Chemical Elements
thDuring the 16 century, sophisticated tools began to emerge. People studied jars of various gases. Results of these studies led scholars to reject Plato's primal substances as natural units.
New concepts began to emerge, and the same fundamental question was asked again. ? What are natural units of material?
How many kinds of units are there?
Van Helmont and Boyle used glass jars to studyA Belgian scientist J. B. van Helmont (1580-1644) gases from combustion and respiration, and theyconfirmed that gas generated from burning discovered that air was not a single substance.charcoal was the same as that generated from
burning alcohol, but different from air. Thus,
there is more than one kind of air (gas).
The rich Englishman Robert Boyle (1627-1691)
also experimented with gases and air. He noticed
the different properties of various gases (air)
produced in his experiments. The behavior of
various gases convinced him that fire, air, water, and earth were not natural units of material. He
published The Sceptical Chymist in 1661 to
demolish the doctrine of primal substances. He used the term element for his natural units and
he defined it as follows.
I mean by Elements, as those Chymists that speak plainest do by their Principles,
certain Primitive and Simple or perfectly unmingled bodies; which not being made of any
other bodies, or of one another, are the Ingredients of which all those call'd perfectly mixt
(i.e. compound) Bodies are immediately compounded and into which they are ultimately