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Appendix B
UNITARY FIELD THEORY
AND QUANTUM GRAVITY
B.1. The process
of unification in physics
B.2. Einstein's visions of
geometric unitary field theory
B.3. Wheeler's
geometrodynamics. Gravity and
topology.
B.4. Quantum
geometrodynamics
B.5. Gravitational
field quantization
B.6. Unification
of fundamental interactions. Supergravity.
Superstrings.
B.7. General
principles and perspectives of unitary field theory
B.1. The process of unification in physics
Naturalists and
especially physicists are deeply convinced of the intelligibility of the world, especially nature. He therefore
strives to find a uniform explanation of the basic building
blocks of matter and the interactions between them. The basis of
scientific thinking is unification : in the vast diversity of
phenomena and events, to seek general
laws and a common
essence, to try to explain the diversity of phenomena on the
basis of as few basic laws as possible. It is based on the idea
that "nature is rich in forms, but
poor in laws".
Thoughtful people have always
longed for a theory that would describe and understand all the
observed complexity and diversity of nature. The ultimate ideal
is (if possible) to explain all the laws of nature using a single
universal principle - to create a
definitive final theory or a unified "theory
of everything" (TOE
- Theory Of Everything); to reveal a
single law clarifying all the phenomena of the world.
Unitarization efforts are based on the belief in the material unity of the world, which
is now the basis of all science. That there is some hidden universal structure in the Universe or the law on the basis of which
the whole universe works. And it is physics that examines the
most basic laws of nature, that has a unifying
role among
all the natural sciences. In the course of development, with the
discovery of ever new phenomena and laws, physics seems more and
more complicated, demanding and complex. However, this is
only a partial external view. Within physics, in fact, there is also an integration process, the aim of which is to give a uniform description of physical phenomena.
Unitary
"theory of everything": the end of physical research ?
Sometimes we encounter the opinion (especially in the
scientific-popularization literature) that the successful
construction of a unitary theory of the field, the "theory
of everything", would mean the end of physics
inverstigation and even perhaps the whole of science
research - there would be nothing new to discover! This opinion
is wrong for at least two reasons :
1. Quantum relations
of uncertainty, if the new unitary theory did not
overcome them in any way (which does not seem probable),
fundamentally limit the possibilities of predicting phenomena.
2. We cannot solve the
relevant equations accurately, except in the simplest and
idealized cases. With the number of degrees of freedom (the
number of bodies and particles) this becomes completely
impossible, an attempt to make an accurate prediction necessarily
dissolves into chaotic behavior (it is discussed
in more detail in §3.1, section "Determinism
- chance - chaos?").
The unitary theory, understood as the final "theory
of everything", certainly does not explain
everything! It will only provide us with a basic unified
theoretical framework of how the physical interactions of fields
and particles work at the deepest level of essence. It probably
won't change anything about the proven knowledge about the
functioning of real nature and the universe. In practice, it will
not allow us to predict the future, nor to reconstruct the past.
In astrophysics and cosmology, it may help us understand
phenomena around hypothetical singularities inside black holes or
at the origin of the universe. However, for the astrophysical
behavior of the real universe, the informative value of the
"theory of everything" will probably be marginal...
So there is still a lot of intellectual work to
be done, how to derive and understand the behavior of
systems in complex and realistic situations from basic principles
and laws. This work, with its fundamentality, complexity and heuristic
significance equalizes by revealing the principles of
unitary field theory.
Basic
stages of unitarization
The basic stages of unification in physics are shown in Fig.B.1.
The first stage of unitarization actually
took place in the very beginnings of physics as a science: it was
a unification of "terrestrial"
and "celestial" mechanics.
Thanks to Galileo, Copernicus and Kepler, it became clear that the laws of nature observed
here on Earth also apply elsewhere in the universe (the first more concrete confirmation of this was
Galileo's observation of "mountains" on the surface of
the Moon). For real
"father of unification" can be considered to I.Newtona
that before about 300 year those formulated the law of universal gravitation and showed that the force of the
Earth's gravity causing bodies to fall is identical to the force
of keeping planets in orbit around the Sun, i.e. cosmic gravity.
The "classical" period
of unitarization of physics can also include the unification of mechanics and thermals in the kinetic theory of heat,
according to which the essence of thermal phenomena (formerly considered separate) is the kinetic energy of disordered and
oscillating motion of particles (molecules and atoms) in
matter.
A great example of unitarization
in physics is the unification of
electric and magnetic forces which previously seemed to be
quite different forces of nature. In the first third of the 19th
century, Faraday and Ampér discovered that magnetic forces
(known until then only from permanent magnets) are created by the
movement of electric charges. And changes in the magnetic field
cause an electric field. This knowledge was further developed and
generalized by J.C.Maxwell in his electromagnetic
field theory (§1.5). The consequence of the unity of electricity
and magnetism in Faraday-Maxwell electrodynamics is the existence
of electromagnetic waves, which are emitted during the
accelerated motion of electric charges.
The properties of these
electromagnetic waves proved to be identical to the properties of
light: there was also in addition optical and electromagnetic
phenomena were unified. Radio waves, heat radiation,
light, X-rays and gamma rays, together with the classical and
relativistic effects of electricity and magnetism, are therefore
just different manifestations of electromagnetic
interaction.
Fig.Bl Basic stages of unification of
natural laws.
Weak and strong interactions and
unification of individual types of interactions are not yet
included in this scheme; the continuation of the scheme of
unitarization in the field of unitary field theories is shown in
Fig.B.8 in §B.6 "Unification of fundamental
interactions. Supergravity. Superstrings.".
The development of atomistics and quantum
mechanics
in the first third of the 20th century showed that all the
diversity of chemical phenomena can be explained by
electromagnetic interactions and quantum laws in the electronic shells of atoms of individual elements; the same
applies to the physical properties of solids (crystal lattices - elasticity, strength, dislocation), liquids and gases. Thus,
chemistry was in fact "absorbed" by physics, at least
as far as the foundations are concerned - see §1.1 "Atoms and Atomic
Nuclei", section "Interaction of Atoms" of the book "Nuclear Physics and Physics of Ionizing
Radiation".
The other two stages of unitarization are
already related to relativity
theory. In
his special theory of relativity Einstein unified
space and time into a single space-time continuum, in his general theory of relativity
then he unified space-time and gravity - he showed that Newtonian
gravity and inertia are a together manifestation of geometric
properties (curvature) of space-time, which has a dynamic
character (Chapter 2 "General theory of relativity - physics
of gravity").
The last stage of
unitarization takes place in the area of "elementary"
particles. A huge amount of experimental
knowledge about the properties and interactions of elementary
particles, obtained in the 50s-80s, processed and unified in the
spirit of a number of quantum-theoretical concepts, resulted in
the so-called Standard Model of Elementary Particles
and their interactions (it is discussed in
more detail in §1.5 "Elementary particles and
accelerators", passage "Standard
model - unified understanding of elementary particles" of the book "Nuclear physics and physics
of ionizing radiation"). All
matter in nature in its deepest interior consists of only 2
"families" of basic (elementary) particles - 6 leptons
and 6 quarks, between which 4 fundamental forces
(interactions) act: strong, electromagnetic, weak and
gravitational. The first three of these interactions are
described by exchanges of intermediate bosons with spin 1: strong
interaction is mediated by gluons, electromagnetic
interaction by photons, weak interaction by heavy
intermediate bosons charged (W+,
-) and neutral (Zo). Quantum theory for
the gravitational interaction has not yet been completed, but can
be described by intermediate gravitons (spin 2). The modern unitary theories that try
to unify the various types of interactions between elementary
particles, will be mentioned at the end of this chapter (§B.6 "Unification of fundamental
interactions. Supergravity. Superstrings.").
But before that, let's talk about geometric
unitary theories, that are most closely related to the
subject of this book.
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A. Mach's principle | B.2. Einstein's visions of geometric unitary field theory |
Gravity, black holes and space-time physics : | ||
Gravity in physics | General theory of relativity | Geometry and topology |
Black holes | Relativistic cosmology | Unitary field theory |
Anthropic principle or cosmic God | ||
Nuclear physics and physics of ionizing radiation | ||
AstroNuclPhysics ® Nuclear Physics - Astrophysics - Cosmology - Philosophy |