Phlogiston theory, [24] (which will be discussed in later lectures in this book),
that has appeared at the beginning of the 18th century describes the combustion of
some stuff as a release of the hypothetic substance called phlogiston. For instance,
by combustion of a metal, metal loses phlogiston and transforms in the lime (the
historical term for oxide). To recover the original metal, the lime should be heated
with substances that are reach of phlogiston, like coal. Such a way, phlogiston is
returned back to the metal. Thus, phlogiston is a chimeric stuff that could be
exchanged between various substances. In words of modern chemistry, the release
of phlogiston is oxidation, and addition of phlogiston is a reduction. If we are
thinking in analogies, we could easily replace the word phlogiston with the word
electron, and get the concept of oxidation and reduction. The role of phlogiston for
chemists in 18th century could be compared with the role of electron after its
discovery two centuries later.
The triumph of physical science in the history was certainly the appearance of
quantum mechanics, thanks to Heisenberg 1925, and Schrödinger 1926. Since the
principles of quantum mechanics will be discussed in the lecture about chemical
bonds and reaction mechanisms, here I present only the basic principles. In the
frame of quantum mechanics, the system is outlined by one infinitesimally complex
and abstract mathematical function that represent a «superposition» of all the
possible configurations. Let us imagine a system in a closed room. Since we don’t
have the insight in the events in this space, it could be concluded that in this room is
a superposition of all possible scenarios. By opening the door of this room, we can
find the configuration of existing states. However, by this action, opening the door,
the superposition of all the possible configurations is destroyed, and only one state
is detected! In other words, opening of the door caused a «collapse of superpositions» and the emergence of only one configuration. In mathematical interpretation
of quantum mechanics, the function that describes the set of all the states has been
subjected by operator, i.e. opening of the door, and we got the concrete visible
state, but in the same time, we have cancelled the superposition. Thus, the wave
function for electrons describes all the possible states of electrons, but by decision
to use experiment for measuring their energy, say by action of the operator of
energy, the superposition is cancelled and we provide a spectrum of measurable
energies, so called eigenstates. Reception of the world by such method depends,
accordingly, on our selection of the experiment, i.e. about the use of the operator
that provide information of interest. Since all the other states of the system collapsed by action of operator, it is not possible to act by another operator on the same
system. It follows that experimental measuring of one property (for instance
energy) has the consequence that all other properties (for instance the position of
electron in the space) become uncertain and undeterminable. Such approach is in
the core of the quantum mechanics, and it is called the Heisenberg uncertainty
principle.
The question is, whether chemistry, independently on the developments of
physic, has formulated similar concept, at the least on the metaphysical level?
During the first fifth of the last century, chemists were preoccupied by interpretations of molecular structures, and by the principles of the changes of molecular
1 Chemistry and Philosophy of Science
15
that has appeared at the beginning of the 18th century describes the combustion of
some stuff as a release of the hypothetic substance called phlogiston. For instance,
by combustion of a metal, metal loses phlogiston and transforms in the lime (the
historical term for oxide). To recover the original metal, the lime should be heated
with substances that are reach of phlogiston, like coal. Such a way, phlogiston is
returned back to the metal. Thus, phlogiston is a chimeric stuff that could be
exchanged between various substances. In words of modern chemistry, the release
of phlogiston is oxidation, and addition of phlogiston is a reduction. If we are
thinking in analogies, we could easily replace the word phlogiston with the word
electron, and get the concept of oxidation and reduction. The role of phlogiston for
chemists in 18th century could be compared with the role of electron after its
discovery two centuries later.
The triumph of physical science in the history was certainly the appearance of
quantum mechanics, thanks to Heisenberg 1925, and Schrödinger 1926. Since the
principles of quantum mechanics will be discussed in the lecture about chemical
bonds and reaction mechanisms, here I present only the basic principles. In the
frame of quantum mechanics, the system is outlined by one infinitesimally complex
and abstract mathematical function that represent a «superposition» of all the
possible configurations. Let us imagine a system in a closed room. Since we don’t
have the insight in the events in this space, it could be concluded that in this room is
a superposition of all possible scenarios. By opening the door of this room, we can
find the configuration of existing states. However, by this action, opening the door,
the superposition of all the possible configurations is destroyed, and only one state
is detected! In other words, opening of the door caused a «collapse of superpositions» and the emergence of only one configuration. In mathematical interpretation
of quantum mechanics, the function that describes the set of all the states has been
subjected by operator, i.e. opening of the door, and we got the concrete visible
state, but in the same time, we have cancelled the superposition. Thus, the wave
function for electrons describes all the possible states of electrons, but by decision
to use experiment for measuring their energy, say by action of the operator of
energy, the superposition is cancelled and we provide a spectrum of measurable
energies, so called eigenstates. Reception of the world by such method depends,
accordingly, on our selection of the experiment, i.e. about the use of the operator
that provide information of interest. Since all the other states of the system collapsed by action of operator, it is not possible to act by another operator on the same
system. It follows that experimental measuring of one property (for instance
energy) has the consequence that all other properties (for instance the position of
electron in the space) become uncertain and undeterminable. Such approach is in
the core of the quantum mechanics, and it is called the Heisenberg uncertainty
principle.
The question is, whether chemistry, independently on the developments of
physic, has formulated similar concept, at the least on the metaphysical level?
During the first fifth of the last century, chemists were preoccupied by interpretations of molecular structures, and by the principles of the changes of molecular
1 Chemistry and Philosophy of Science
15