Fig.1.0.1. A wide range of sizes of objects in our world, explored by various fields of physics and natural sciences using various tools.
| AstroNuclPhysics ® Nuclear Physics - Astrophysics - Cosmology - Philosophy | Physics and nuclear medicine |
1.
Nuclear and radiation physics
1.0. Physics -
fundamental natural science
1.1. Atoms and atomic
nuclei
1.2. Radioactivity
1.3. Nuclear reactions and nuclear energy
1.4. Radionuclides
1.5. Elementary particles a
accelerators
1.6. Ionizing radiation
1.0. Physics - fundamental natural science
In this introductory chapter we will try to outline some methodological aspects of the construction of physics and its integration into the context of other natural sciences and scientific knowledge in general. These methodological notes may be interesting, for example, for students and those interested in non-physical professions who want to get a comprehensive picture of the physical aspects of the study of nature. And maybe they can stimulate the joy of some readers to learn how our beautiful world and the whole universe works ...
Nature and its
exploration
We will not explicitly define the concept of nature,
about which everyone has a more or less clear intuitive idea. We
will adhere to the universalist concept that
nature is absolutely everything that is, it has
an objective existence. So it is basically the whole
Universe with galaxies, stars, planets including the
Earth, our terrestrial nature - mountains, rivers, sea, all flora
and fauna, all atoms and subatomic particles anywhere on Earth
and in space. Even we humans and cells in our body with complex
biochemical reactions, all our creations.
After all, even some "mental" processes and ideas, if
(at least in principle) it is possible to identify and locate
their "coding" in the neural network of the brain, can
be included in the general term "nature".
At the heart of all scientific research
lies the process of categorization. Reality,
which is too complex and diverse in its complexity *), is divided
into simpler groups according to certain criteria - categories,
that we examine separately. The results of the research of
individual categories can then be generalized and possibly synthesize
- to summarize them into a more general framework, encompassing a
wider group of phenomena - the whole. The analytical and
synthetic approach, in their dialectical unity, forms a general
method of scientific cognition of reality.
*) The world is full of "hiding
places". Science seeks to "hunt" fragments of
knowledge from these hideouts and put them into a mosaic of
complex and objective human knowledge.
Constant inquisitive questions "why?"
can lead us to the basic principles of nature ...
Knowledge: science + experience
The knowledge of every (educated) person is based on two
components :
¨ Science
, providing objective, universal and reproducible knowledge.
However, these communicated findings may not always be properly
understood and interpreted.
¨ An experience
that may be subjective and sometimes erroneous, but if it
reflects reality, can provide a sharper and more concrete insight
into reality.
The unity of these two components
creates a sound and clear human mind, enabling
us to orient ourselves correctly in the events of our world
through critical thinking. Physicists and other
naturalists, as well as clever people of various specializations,
believe only in the objective observations,
measurements and reasoning based on them, confirmed by
independent observers and researchers. Unreproducible, unverified
and controversial claims ("one lady
was talking", "a self-grown genius speculated") cannot become part of scientific knowledge..!..
The more
complex situation is with phenomena inaccessible to our sensory
knowledge - phenomena in the microworld or very distant universe,
where we must rely on research using instrumental methods
(test tubes, accelerators, detectors, telescopes, etc.) and learn
to analyze, reflect and apply the facts found. With the heroic
efforts of researchers, these complex methods have succeeded in
gaining far-reaching, previously unsuspected, knowledge about the
internal
structure of matter and the structure
and evolution of the universe that are
objective and "they work"...
"Ladder" of
knowledge
Gradual knowledge of nature, universe, life is sometimes similar
to a ladder, whose "rungs" are partial
discoveries, the results of experiments, astronomical
observations. However, unlike the ordinary ladder from which we
pluck fruit from the trees in the garden, we do not see the end
of this "ladder of knowledge": more and more steps are
continuously built as you climb the ladder of knowledge. The
question is whether sometime in the future we will encounter the
last, "final rung of the ladder of knowledge", or we
will discover the secrets of nature and the universe one after
the other constantly..?.. Experience to date shows, that
each new level of knowledge and solution of a certain problem
brings new and new questions, often even deeper and more
fundamental...
Informations
- Education - Wisdom
The present world is full of information. However, knowledge at
the level of information does not necessarily mean education and
wisdom. Knowledge itself can be empty. In order
for knowledge and information to gain real meaning and value - to
turn into education and then to wisdom, a comprehensive
multi- stage path of knowledge must be carried
out :
¨ Acquisition
of factual information and knowledge - study, communication with
others, personal experience, observation, scientific research.
¨ Internal
understanding of this information, searching for their
interrelationships and their context in other areas.
¨
Putting knowledge and skills into practice, their
confrontation with various changing circumstances.
¨ Ask
new questions about the essence of these
phenomena and events, try to find an explanation. To draw from
them conclusions useful for "one's own soul" - for
one's worldview, relationships with nature and
one's neighbors.
Each of these stages also presents certain risks
of errors and wandering in the way. E.g. at the last
point, it sometimes happens that on the basis of only a
superficial study, partial knowledge and insufficient
understanding, we hastily come up with a bizarre and erroneous
explanation. Some people with a lack of self-reflection persist
in these misconceptions stubbornly; they call them
"alternative science" (we often encounter the work of
various "ingenious authors" refuting the theory of
relativity or building far-reaching "unitary theories"
of matter and space based on psychotronics, various
"energies", subtle and gross-mass, and a similar
arsenal of misunderstood concepts...) - see also "Quackery
versus science", below
"New" and
"old" physics - continuity of scientific knowledge".
Interpersonal relationships are often based on
emphasizing the "self", which leaves little room for
understanding and listening to others, for appreciating their
strengths and experiences that could enrich the "our
self". The current trend dictates people to be
informed. However, the overabundance of information
often hinders its real understanding and use - it is actually an obstacle
to achieving real education and, above all, wisdom - "less
is sometimes more".
"Alternative"
science ?
Under the often used name "alternative science",
two fundamentally different approaches can be hidden :
¨ Different (alternative)
ways of explaining and interpreting reliably
identified phenomena and facts that are different from the usual
prevailing interpretation in a given scientific discipline. This
is a completely legitimate attempt for a
possible better explanation of the analyzed phenomena and
possibly prediction of new phenomena. If this concept does not
work, its authors are "without blinking" willing to
abandon it and join a more probable and proven theory.
¨ An alternative to science
- diametrically opposed views of lay people, often based on an
incomplete and insufficient understanding of the problem and an
attempt at a "completely different" as
if "original" explanation. These are
mostly mistakes, pseudo-sciences,
to which its proponents often cling stubbornly despite their disagreement
with experimental facts ("Quackery
versus science") .
Distrust of an official scientific opinion can sometimes
be quite honestly motivated. For our understanding of nature,
Newtonian classical physics would certainly be more
comprehensible than the theory of relativity and quantum physics.
Why is nature so complicated? Unfortunately, real nature is
governed by more complex laws theories of relativity
and quantum physics, with which we have no
experience in everyday life. Experimental findings show this
completely uncompromisingly! Physics never invents an
unnecessarily complex description and explanation of objective
reality, but only one that is essential for the correct
explanation of experimental facts. For an intuitive understanding
of relativistic and quantum laws, illustrative models
have been developed to help every educated and thoughtful person
at least provide a general understanding of the specific laws of
the microworld and megasworld, as well as their role in the
functioning of our nature, life and the Universe.
Nevertheless, some contemplators (or
rather "sages", "reasoners", "rocket
scientists") do not follow the proven Chinese proverb "Thinking
without study is dangerous! ", without proper
study and understanding, they do not hesitate to reject all the
knowledge gained through the hard work of generations of erudite
experts and seek at all costs to promote some own "ingenious
solution" (see the already mentioned
discussion"Quackery versus science"). In the physical
sciences, these deformations are less common, physicists
immediately recognize delusional concepts, and the general public
usually does not address them. Frequent
pseudo-scientific distortions are in the biological and
especially in the medical fields, where so-called alternative
medicine receives promotion and great financial support
from companies that profit from the sale of often ineffective
medicines (eg homeopathic). In the field of biology and medicine, there are
complex "tangled" and little reproducible phenomena and
processes, so possibly mistakes and frauds are difficult to prove
here.
Division of nature
You can divide nature into categories using various criteria. The
oldest division of nature, which we each
encountered at the earliest childhood during the first steps of
knowledge, is the division of nature into living
and inanimate nature. From a human point of
view, we approach living nature with greater sympathy for
belonging to the "living to the living" than to the
inanimate. From a physical point of view, however, the division
into living and inanimate nature is pointless
*): the same basic laws of nature apply to both inanimate and
inanimate nature.
*) We disregard here the fact that it is
sometimes difficult to decide whether to classify some simple
organic systems as living or non-living; this is a narrower
problem of molecular biology and organic biochemistry.
Also, another simple division of nature into terrestrial
and cosmic is obsolete and physically
unjustified: we now know that the natural processes
taking place here on Earth, even in the farthest reaches of the
universe, are governed by the same universal laws of
physics.
The really substantiated and objective division of
nature according to the prevailing and determining
physical laws is as follows (Fig.1.0.1 below) :
These three categories of nature do not have sharp boundaries and often intersect. Even distant regions such as the megasworld and microworld - such as thermonuclear reactions inside the Sun or distant stars ("The role of gravity in the formation and evolution of stars"), and even the processes of the formation of the universe itself ("Big Bang" - Standard Cosmological Model The Big Bang The Formation of the Structure of the Universe. ), are governed by the quantum laws of nuclear physics and the interactions of the elementary particles of the microworld.
How does physics and natural sciences study our
world ?
A huge variety of sizes, shapes and composition of objects in
nature, as well as the processes occurring in them, requires a
number of very different research methods and tools - often very
cleverly designed instruments. In middle row Fig.1.0.1 are
symbolically shows the typical objects in nature
- from particles, nuclei, atoms, molecules, through cells with
their organelles and DNA, organisms, planets, stars, galaxies, to
the whole universe. The line below it shows the tools
with which we examine the relevant objects. The upper part of
Fig.1.0.1 lists the fields of science that deal
with the study of relevant objects and the basic physical
categories that relate to them. Below is the figure is a
scale of object dimensions (from
the smallest so-called Planck-Wheeler length 10-33 cm [is derived and discussed in §B.4 "Quantum geometrodynamics" in the monograph "Gravity, black holes
and space-time physics"], through
particle and atom pictometers, cells
micrometers, millimeters and meters of organisms,
kilometers of forests, mountains, seas and other objects of
terrestrial nature, thousands and millions of kilometers of the planetary
system, billions of kilometers, light years to billions
of light years of distant space; to infinity
of open universe...).
Fig.1.0.1. A wide range of sizes of objects in our world,
explored by various fields of physics and natural sciences using
various tools.
Let's start with the usual macro
world in the middle part of Fig.1.0.1 and we will first
continue towards smaller scales. We carry the most important
observation tool with us: it is our eye - an
optical system that projects light through a lens on the retina,
where an image is transmitted to the neural network in the brain.
Using ocular vision, we observe and examine all common
macroscopic objects from a fraction of a millimeter (where we can help with a magnifying glass) to tens of kilometers (here we
help with binoculars).
For cognition of tiny objects and structures the size of
hundredths and thousandths of millimeters, such as cells and
organelles inside, we use a microscope - the
optical system of the lens and eyepiece, which can achieve a
magnification of up to about 3000 times. The invention of the
microscope played a huge role in biology and
medicine, which, from the originally "charlatan"
disciplines, with a number of errors and unfounded assumptions,
thus became exact natural sciences. The realization that
all living organisms are composed of cells with
a complex internal structure, was followed by an investigation of
the complex biochemical and molecular genetic processes that are
the essence of life. This research is still
ongoing.
For the study of even smaller structures
in the field of molecules and atoms, in the sphere of the microworld,
the most perfect optical microscope is already powerless: the
wavelength of visible light is many times larger than the
dimensions of atoms and molecules *). We cannot observe something
as subtle as atoms with something as coarse as light! No man can
ever see the structures of molecules and atoms with his eyes. To
study them, indirect laboratory methods of atomic and
nuclear physics must be used. The most important method
here is spectrometry (especially electromagnetic
radiation): we excite atoms or nuclei by a suitable supply of
energy; during subsequent deexcitation, radiation is emitted, the
energy distribution of which - the spectrum - is measured. From
the results of these measurements we deduce the internal
structure of the molecule, atom or nucleus. ........
*) An electron microscope
may be used in the "intermediate stage" of the micro -
dimensions, which is able to achieve a magnification of 100,000
times or higher. We can display small intracellular structures,
viruses, larger macromolecules.
Scattering experiments are another
important method of studying atoms, nuclei and particles.
Examined atoms or their nuclei we shoot with
suitable particles (electrons, protons, alpha particles,...) on
the appropriate energy and investigate at what angle to
"reflect", respectively scatter. At lower energies
there is usually elastic scattering, at high energies
inelastic or "deep" inelastic scattering.
Using Rutheford's scattering experiment with alpha
particles, it was possible to reveal the internal structure of
the atom - the atomic nucleus and the electron
shell (§1.2, part "Structure of atoms", Fig.1.1.4).
To know the structure of elementary particles
and the nature of the forces acting between them, it is necessary
to implement particle collisions at the highest
possible energies on accelerators (§1.5, section "Particle accelerators") - to achieve deeply
inelastic scattering or "breaking" of particles; in the
assortment of "research tools" in Fig.1.0.1 lies on the
left margin. In such collisions, the particles penetrate each
other "deep into their interiors" and the result of the
interaction can tell something about their structure. Due
to quantum processes in the fields of strong, weak and
electromagnetic interactions, new secondary particles are formed
during high-energy collisions, which are both
interesting in themselves and carry important information about
the properties of the fundamental forces of nature, including the
possibility of their unified understanding within the unitary
theory of the field. Particle collisions at high energies
are a kind of "probe" into the deepest interior of
matter - and at the same time into the processes of universe
formation (see §5.5 "Microphysics
and Cosmology. Inflation Universe." books "Gravity, Black Holes and the Physics
of Spacetime"). It can be said that large
accelerators are the most powerful "microscopes"
into the interior of matter and, with a bit of
exaggeration, also the largest "virtual telescopes"
in space, which make it possible to
"see" up to the very early stages of the evolution of
the universe, where no other astronomical telescopes can see
anymore. Of course, this is no a direct
observation of physical phenomena in the early universe, but
their faithful if possible experimental simulation:
Processes that we investigate at accelerators at high-energy
particles interactions, probably took place in the first
microseconds after the formation of the universe - just after the
"big bang". We can help us understand
the origin and evolution of the universe.
If we go the other way now - from the
macroworld towards large scales to space, to
observe planets, stars and their systems, nebulae, galaxies, we
use large astronomical telescopes (§1.1, part "Electromagnetic radiation - the basic source of
information about the universe" in
the book Gravity, black holes ...) . These
telescopes often have spectrometers installed in
their focus, analyzing the wavelength of incoming light. This astronomical
spectrometry is a powerful tool for understanding
chemical composition, temperature, speed of motion of
objects located at distances of thousands, millions or billions
of light years, where no one ever has a chance to physically
look! Astronomical telescopes (optical and
infrared) are sometimes sent outside the Earth's atmosphere, into
orbits around the Earth. In addition to optical
telescopes, radio telescopes are also used, whose antennas
capture electromagnetic radiation of longer wavelengths (units or
tens of centimeters). Important information about
the formation of the universe is provided by the measurement of relic
microwave radiation ( §5.4, passage
"Microwave relic radiation
- messenger of reports about the early universe" in the book "Gravity, black holes ...").
Important "windows" into space is gradually
becoming the detection of cosmic rays (§1.6 , part
"Cosmic rays"), neutrinos (§1.2,
part "Neutrinos - "ghosts" between particles"), recently and especially
in the future also gravitational waves (§2.7
"Gravitational waves" in the monograph "Gravity, black holes ...
").
Natural
sciences
In the distant past (antiquity and the
Middle Ages) there was only one science
called philosophy, which covered all areas of
human knowledge at the time - society, nature, medicine,
religion, history, etc. There was little real knowledge,
speculations and guesswors prevailed, conventional traditional
views and religious dogmas.
A brief overview of the development of knowledge about
nature, especially about universe, space, time,
electricity and gravity, from antiquity to the present, is given
in §1.1 "Historical development of knowledge about
nature, space, gravity"
book "Gravity, black holes and physics spacetime").
With the growing knowledge of nature, it
was no longer possible to encompass everything within the
framework of philosophy, from which the natural sciences
were therefore gradually separated and earmarked. The basic
division of natural sciences is based on the main areas of
natural phenomena and objects they deal with :
The mentioned methodological
procedure, in which biological processes are explained by
chemical reactions and chemical reactions in turn by physical
electrical interactions of atoms, is called reductionism
- we try to reduce and explain more complex phenomena by
means of simpler phenomena. In general, this approach is very
fruitful and successful in science. However, a permanent subject
of discussion between scientists and philosophers is the question
of whether this reductionist scheme of biology Ü chemistry
Ü physics can or cannot be (at least in
principle) applied to higher nervous activity - psychological and
mental processes in the human mind ..?..
In the past, around the end of the
19th century, the individual disciplines developed largely
independently and closedly, and the progress of knowledge was
relatively slow. The later impressive development of knowledge
was caused mainly by two factors :
¨ Technical
progress in observational and experimental techniques,
which provided an insight into the previously unrecognizable
scales of the microworld and the megaworld ;
¨ Interdisciplinarity - overlap of individual special
disciplines into other disciplines (neighboring
and distant), cooperation of various
disciplines in solving issues of knowledge of complex phenomena.
E.g. application of knowledge of nuclear physics to processes in
stars - nuclear astrophysics
(§4.1 "The role of gravity in the
formation and evolution of stars" books "Gravity, black holes and space-time
physics"), or chemistry and physics on
processes in cells - molecular biology and genetics,
biochemistry and biophysics (§5.2, part
"Cells - basic units of living
organisms"), led to fundamental qualitative progress of our
knowledge.
Methodological division
of physics
According to the method and style of work in the study of natural
laws, physics can be divided into three areas :
Field
division of physics
According to specific groups of studied natural phenomena,
physics is divided into a large number of disciplines and
specializations (there are more than a hundred), of which we list
only a few of the most basic (each has a number of subfields and
specializations, including interdisciplinary) :
In addition to specialized physics disciplines, dealing with specific groups of phenomena, the structure of physics also includes two important theoretical concepts of modern physics, which have a more general character and go "across disciplines" :
Gnoseological
note:
Can we understand
relativistic and quantum physics ?
We humans and previously life here on Earth have evolved over
millions of years in an environment of sunlit seas, lakes and
rivers, mountains, minerals, the atmosphere. Along with our
entire biological bodies, our brains are completely fixed
on a "moderate" macroscopic environment
with low speeds, short distances, weak gravity and small other
forces, low temperatures in the range of several hundred to
thousands of degrees. From this natural environment we have long
ago "learned" the laws of classical mechanics, later
thermals, hydrodynamics, solid state physics, electricity and
magnetism, chemistry, biology, etc. Only here "we are at
home" ..!..
We have no personal experience with speeds
of hundreds of thousands of kilometers per second, thousands of
times greater than those of any ordinary macroscopic object, or
with sub-tiny particles of the size of a millionth of a
millimeter, invisible even by the best microscopes. The laws of
relativistic and quantum physics are therefore not close
to us and we do not understand them; they have only
recently been discovered through complex
experiments, precise measurements, sophisticated
analyzes ...
In order for us "ordinary
mortals" (relativistic or quantum
"non-specialists" *) to understand at least some
of the quantum laws of the microworld and the relativistic laws
of the megaworld, we must necessarily use approximate
models based on classical mechanics. These are "ball
models" for atoms and interactions (collisions) of
particles (see note in §1.5, passage
"Are there any
elementary particles at all? Ball model."), or motions according to classical
mechanics and Newton's law of gravitation - only with
additional necessary quantum and relativistic corrections.
*) Truth be told, even these specialists,
if they dare to descend from the "throne of their
superiority" and honestly realize that they are also
just ordinary people, they admit that they also use
these models ...
Significant scientific discoveries - chance
or method ?
The continuity of scientific knowledge of nature, the origins of
which can be traced back to the 16th century, was from time to
time disrupted - in a positive sense - by
fundamental discoveries that significantly accelerated knowledge
of the studied phenomena, revealed new phenomena or changed the
methodology and direction of research. Let us briefly consider
the role played by chance in these discoveries
and what a systematic methodological approach.
From this point of view, we notice three cases :
¨ The discovery
of the magnetic effect of an electric current made by
H.Ch.Oersted in 1820.
Were it not for the compass magnet to be placed accidentally on
the desk, Oersted would continue to do a number of experiments
with electrical circuits, but he would not notice the connection
between electric current and magnetism.
¨ Discovery
of X-rays made by W.C.Röntgen in 1895.
It is briefly described in §3.2 "X-ray diagnostics". Without covering the discharge tube with black
paper and lighting up a randomly placed screen, Roentgen might
not have inserted various objects (including his hand) between
the tube and the screen. He would continue to do interesting
experiments with cathode ray tubes as well as dozens of other
experimenters at the time, but he probably wouldn't find new
penetrating radiation, nor its cardinal significance in medical
diagnosis (after all, this X-ray was
independently discovered by H.Jackson and AACampbell-Swinton at
the same time).
¨ The
discovery of radioactivity made in 1896 by H.Becquerel.
It is briefly described in §1.2 "Radioactivity". Were it not for the accidental deposition of
minerals intended for the study of (light) luminescence on a
light-tight photographic plate and the accidental development of
this (supposedly "clean", unexposed) plate, Becquerel
would continue to examine luminescence excited by sunlight and
invisible radioactive radiation emanating from certain
substances, he would have no idea...
Is it possible to judge from the history of these and
many other cases that significant discoveries are perhaps the
result of mere chance? Definitely not
! The well-known saying "coincidence wishes the
prepared" applies here. These researchers were experienced
experimenters and carried out their experiments systematically
with a well-thought-out methodological approach.
Coincidence only directed this methodological
approach so that it resulted in the final discovery of a new
natural phenomenon. An inexperienced experimenter might rule out
some observed phenomena (if he noticed them at all), which do not
fall within the scope of the current assumptions, he would
consider them as accidental errors. E.g., he would throw away a
photographic plate that is blackened as a bad, even though it
should not be ...
Moreover, even if the aforementioned
"coincidences" did not occur and Oersted, Röntgen ,
Becquerel and other well-known researchers from the textbooks
would not make their discoveries, someone else
would soon do so. There were a number of
experienced researchers diligently conducting top experiments at
the time, the unresolved problems were mostly "matured"
and it was only a matter of time before the experiments were
carried out, which would bring new "light" and
direction. At present, basic scientific (especially physical)
research has clearly reached the level of a systematic
methodological procedure, in which entire teams composed of
experts from various specializations participate, using mostly
very complex and expensive (often very large) experimental
equipment. But even the opposite statement that "chance
has no place here" can not be considered justified ...
"New" and "old" physics
- the continuity of scientific knowledge
With the advancement of scientific knowledge, it naturally
happens that earlier ideas and theories are no longer sufficient
to explain newly discovered phenomena and facts - they are
replaced by new theories. In the lay public and
popularization literature, we often come across the claim that
"a new theory has refuted or demolished the existing
theory", or even "a new physics has refuted
old physics". This opinion is completely wrong
! This was partly the case in the past in the transition from the
pre-scientific period, when some unverified and
erroneous views and speculations would be refuted
and replaced by theories of already real science, based on facts.
The current natural science - especially physics - however, it no
longer proceeds in this way.
In natural science (and in physics in particular) the continuity
of scientific knowledge applies. New discoveries and new
theories do not refute the experimentally
verified findings of the previous theory, but supplement,
refine and generalize these theories to newly
discovered phenomena which the previous conception is no
longer able to fully explain; it contains an earlier theory as a limit
case. It also allows for a deeper understanding of
phenomena in a broader perspective - what is "behind
it".
We can approach this with the example of the theory
of relativity and quantum physics. Einstein's special
theory of relativity does not refute the classical Newtonian
mechanics, which is its limit case for small velocities compared
to the speed of light. However, it specifies the laws of motion
so that they apply exactly even to high speeds. Similarly, the
general theory of relativity does not refute the classical
Newton's law of gravitation, which remains valid as a limit case
of weak gravitational fields. Einstein's equations of the
gravitational field are generalizations, valid even for extremely
strong gravity. What is fundamental and new to the theory of
relativity is a new look at the properties of space and time (see
"Gravity, black holes and the physics of spacetime") - but again it manifests itself only under
"extreme" conditions; in the ordinary macro world, the
classical conception of space and time in the spirit of Euclid
and Newton will suffice.
Similarly, the relationship between classical and
quantum physics is formulated as the so-called correspondence
principle : In the limit of large quantum numbers, the
difference between quantum and classical physics is blurred,
quantum physics becomes classical. Or for large quantum numbers,
quantum physics gives the same results as classical physics.
This relationship of continuity and correspondence will
undoubtedly apply to future theories. If it is possible to
successfully build unitary field theories, it will not disrupt
the functioning of the laws of the existing theories of
individual separate "partial" fields (electromagnetic,
gravitational, nuclear forces) in conditions where they are
experimentally verified. However, it predicts and explains new
phenomena at extremely high energies of interactions, perhaps
including phenomena in the formation of the universe, for which
the existing theory is not enough.
The direction of
scientific deduction
Scientific interpretation is based on deriving
one knowledge from another. However, it is not just a simple
deduction. For real knowledge and understanding of the context,
the formal logic of deduction is not enough, but from the
heuristic point of view, the direction of deduction
is also important - from more fundamental laws or theories to
more special ones. An example is Newton's law of gravitation,
derived by its author from Kepler's earlier laws describing the
orbit of planets in the solar system. However, from the point of
view of scientific knowledge and explanation of the essence, the
law of gravitation (along with Newton's three laws of mechanics)
is undoubtedly far more fundamental a law that
explains Kepler's laws (and much more...) - and not the other way
around! Or another example: The laws of special relativity (STR)
were derived by Lorentz and Einstein based on the electrodynamics
of moving charged bodies. Now, however, STR is a general concept
going "across" the fields of physics, which is no
longer logical to explain and derive from electrodynamics, but
rather to analyze the movements of charges in electric and
magnetic fields with the help of STR.
Simplicity and
logical economy
Another important principle in building physical (and in general
natural-scientific) theories is simplicity and logical
economy in terms of the number of concepts, reasons,
causes introduced; these entities should not
multiply more than necessary. This principle of the
so-called Occam's razor *) - the principle of the
simplest explanation of things - solves the problem of an
infinite number of diverse, in principle admissible alternative
theories, which lead to the same results in explaining a certain
natural phenomenon. Occam's razor "cuts off"
superfluous concepts, assumptions, and theories, leaving only the
plausible, logically necessary, and rational ones; if there is
more than one explanation for a phenomenon, it is reasonable to
prefer the least complicated one.
*) It is not a "tool", but a
principle of decision-making between different
theories that have similar practical results. It is named
after the English medieval philosopher William Occam (or
Ockham, 1287-1347), which dealt with the logical
structure of knowledge. The principle of logical economy
("it is useless to do something with more tools when it
can be done with less" ) used against an excessive
number of scholastic principles, properties, essences, forms, and
other imaginary starting points, as was the custom at the time.
In the theories of classical
and relativistic physics, this principle is strictly observed.
However, in some newer physical theories, the situation is more
complicated. In quantum field theory and unitary theories,
auxiliary so-called calibration-gauge fields are
introduced, to which new hypothetical particles correspond (see
"Unification of fundamental interactions.
Supergravity. Superstrings.").
The most difficult situation is then insuperstring theory,
where, in the opinion of some physicists, the principle of
Occam's razor is violated..?..
Refutable of
theories
We can never prove the theory with absolute and definitive
validity, but we can only test it
empirically. Although the theory has been experimentally
confirmed many times, we can never be sure that inconsistencies
will occur in further experiments or measurements - the theory
can be refuted *) by even a single experiment or observation, the
results of which contradict its predictions. A valuable theory is
therefore one that not only agrees with existing knowledge, but
which can be empirically refuted - falsified.
Until that happens, we consider the theory to be correct,
or more precisely adequate. The "irrefutable"
theory is scientifically empty, it has a metaphysical character.
This criterion of the value of the theory is sometimes referred
to as Popper's (according to the Austrian philosopher
K.Popper, who was left with the theory of knowledge in terms of critical
and skeptical realism), "Popper's razor".
Only those theories that admit the possibility of their
refutation or modification are scientifically credible. The
refutability of theories understood in this way enables further
progress of knowledge - the creation of new, more perfect
theories.
*) The word "refute" here does not mean
to completely negate and demolish, but rather to define areas
where it no longer applies - cf. with the continuity of
scientific knowledge discussed above. Physicists understand this constructively
- it is clear to them, that when such a situation arises, it is a
challenge to find a new, more perfect theory. However, for some
people who are not sufficiently erudite and prejudiced, Popper's
criterion of rebuttal may be a pretext for purposeful attacks on
well-established, adequate scientific theories; mostly for the
purpose of promoting theories of biased and erroneous...
Some other philosophical and gnoseological
aspects of revealing natural laws, creating their models
and formulating physical theories are discussed in §1.1, passage
"Natural laws, models and
physical theories"
monographs "Gravity, black holes and the physics of
spacetime".
Rationality - intuition - fantasy in science
The basis of scientific knowledge is undoubtedly a rational
analysis of phenomena in nature, observed either
directly or through experiments. Using this analysis, we conclude
on the common laws that govern natural processes and finally
formulate the relevant laws of nature. However,
in addition to a rational approach, two specific aspects of human
thinking are applied in certain stages of scientific research -
intuition and imagination.
Intuition it represents the ability to know directly without
consciously involving reason and rational reasoning. It is a kind
of "instant insight", a quick immediate understanding
and knowledge; intuition has the character of "sudden
enlightenment", the "sixth sense". From the point
of view of the neurology of the central nervous system, it turns
out that rationality and intuition are a manifestation of the
activity of two different but closely cooperating large
neural networks in the brain. The neural network in
which intuition takes place is developmentally older, its germs
are already manifested in the instincts of animals. The rational
network is developmentally younger, it is specifically human. The
cooperation of both networks can be compared in computer
terminology to a coprocessor, which quickly exchanges the
information written in the neural maps of
individual networks. In a senseis intuition a shortened
and accelerated subconscious running of many possibilities, which
results in choosing the "right" variant... Unlike
ordinary "guessing", in science it is a subconscious
operation of "trained" reason, which can "guess
qualifiedly the right solution". And fantasy
is the ability to imagine things and events differently
than we commonly see and know - modifying some of the maps
written in neural networks.
Intuition is of great
importance in the turning points of scientific knowledge. New
generalizing and unifying natural laws often cannot be
discovered in a logical way - they cannot be derived
rationally, perhaps mathematically, from existing laws, because
they are not contained in them (at least not directly). Here,
intuition helps, which provides a "feeling" for
understanding the implicit laws that are hidden behind certain
phenomena. And it reveals previously underappreciated
similarities, sometimes even between seemingly distant areas. The
rational elaboration of intuitive ideas then creates scientific theories.
An example is the great
intuition of A.Einstein, who, with the help of an imaginary
experiment, noticed the similarity of long-known mechanical
phenomena: the dynamics of motions of bodies in non-inertial
(accelerated) systems and the dynamics of motions of bodies in
the gravitational field. And by adding to this the laws of his
special theory of relativity, he deduced from it a new view of
gravity and curved spacetime - general theory of
relativity (discussed in detail in §2.2 "Universality
- a basic property and key to understanding the nature of gravity"
in the book "Gravity, Black Holes and the Physics of
Spacetime").
Fantasy gives us a number of diverse
possibilities "how it might work" - and it
turns out that some of these possibilities (sometimes even those
that originally appear as "crazy ideas") are actually realized
in nature..!.. - but others are not, it
is not good to overestimate unsubstantiated innovations at all
costs...
For in order to achieve
objective and true knowledge, intuition, as well as a rational
method, must be based on positively ascertained facts and verified
data. The usual mistake of "amateur thinkers"
is that they are based on insufficient, unreliable or distorted
data, moreover, insufficiently understood and not included in the
context of other knowledge. Intuitively, they derive peculiar
ideas from them, whose development (even rational and exact ones)
lead to completely wrong conclusions and
concepts, often without feedback and self-reflection ...
Mistakes and errors in scientific knowledge
In such a complex activity as scientific knowledge, errors
and mistakes also naturally occur. These errors can be
of several types, two of which are basic :
¨ Unsuccessful
experiments and observations, that fail to detect
or confirm the phenomenon being investigated, or to measure the
correct results. The well-known saying "A negative
result is also a result" in scientific knowledge is
profoundly true. A negative result may have two reasons: 1.
Either the initial assumption or hypothesis is wrong
and the investigated phenomenon does not exist
or does not take place under the given conditions, eventually
values of physical quantities are outside the measurable range. 2.
During the experiment or its evaluation, we made errors or
inaccuracies, it was not possible to eliminate the disturbing
influences that "drowned out" the observed subtle
phenomenon. A failed experiment or measure should not lead to
resignation, but to rethink the methodology and improvement of
experimental techniques - perhaps next time or in the future will
succeed ..?..
¨ False
positive experiments and observations, in which
the investigated phenomenon (seemingly) manages to prove or
measures seemingly demonstrable exact values of certain
quantities. However, these results can sometimes be the result of
experimental errors, interferences, misinterpretation. In order
to be able to consider a phenomenon as proven
and the values of the measured quantities to be accurate,
an independent verification in another
laboratory and another group of researchers is necessary,
preferably several independent verifications.
Unfortunately, there are sometimes (fortunately not very
often) deliberate manipulations, even
falsification, of measured results. The motives are different,
mostly prestigious or economic - obtaining funds (from grants and
subsidies) either for your own needs or to finance the activities
of the institute and the project. These disorders are more common
in the biological and medical sciences, where complex
"tangled" and poorly reproducible phenomena and
processes are investigated, so that eventually fraud is difficult
to prove here. In addition, there are often "in the
game" large funds, profits and particular interests
of private companies (eg pharmaceuticals)...
Unitarization
in physics
The basis of scientific thinking and knowledge is unification : in the great diversity of phenomena and
events, to seek general regularities
and a common
essence, to try to explain the diversity of phenomena on the
basis of as few basic laws as possible. Thoughtful people have
always longed for a concept or theory that would describe and
understand all the observed complexity and diversity of nature.
The ultimate (monistic) ideal is 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). And it is physics, which examines the most
basic laws of nature, that has the main unifying role among all the
natural sciences.
A characteristic feature of the
physical view of nature is the already mentioned reductionist
approach and the effort to uniformly understand
the widest possible class of phenomena - unitarization.
This effort runs like a "red thread" throughout the
history of physics - see §B.1 "The
Process of Unification in Physics" of the book "Gravity,
Black Holes and the Physics of
Spacetime".
The first stage
of unitarization actually took place in the very beginnings of
physics as a science: it was a unification of the
"terrestrial" and
"celestial " mechanics.
Thanks to Galileo, Copernicus, Kepler and Newton was becoming
clear that the laws
of nature observed here on earth is true elsewhere in the
universe. Newton's law of universal
gravitation
showed that the force of gravity causing the falling body is
identical with the force holding the planets orbiting orbits,
i.e. with cosmic gravity.
In the "classical"
period unitarizace physics can also include unification
of mechanics and thermodynamics in the kinetic theory of heat, according
to which the essence of thermal phenomena is
the kinetic energy of the disordered and
oscillating motion of molecules and atoms in matter.
An important stage of unitarization in physics was the unification of electrical and magnetic forces, which previously appeared to be
different forces of nature. 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 turned out
to be identical to the properties of light: 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.
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 electron
shells of atoms of individual elements; the same applies to the
physical properties of solids (elasticity, strength,
dislocation), liquids and gases. Thus, chemistry was in fact
"absorbed" by physics, at least in terms of
foundations.
The other two stages of unitarization are
related to the theory of relativity. In his special theory of
relativity, Einstein unified space
and time
into a single space-time continuum,
in general theory of relativity then showed that Newtonian gravity and
inertia are a common manifestation of the geometric properties
(curvature) of spacetime, which has a dynamic character - there was a unification of gravity and
spacetime.
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 (discussed in more detail in §1.5 "Elementary
particles and accelerators", passage "Standard
model - uniform understanding of elementary particles"). 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).
Unification
of fundamental interactions - unitary field theory
The result of the mentioned stages of unitarization was the
finding that all natural events are controlled by only four
types of interactions: gravitational, electromagnetic,
strong and weak interactions. Each interaction is expressed in
physics using the appropriate physical field *).
The unification of interactions thus consists in the creation of
the so-called unitary field theory. The pioneer
of unitary field theory was A.Einstein, who, after creating a general theory
of relativity, worked (though not very
successfully) until
the last days of his life on theories of
unification of the electromagnetic and gravitational fields.
*) Concept of physical field
shows that even though two bodies do not physically touch, they
"touch" or even intersect their
fields. And that causes them to interact with each other.
The idea of unitary field theory is extremely deep and beautiful: according to it, there should be a single, completely basic and all-encompassing physical field, the manifestation
of which would then
be all observed fields in nature - gravitational,
electromagnetic, fields of strong and weak interactions (and possibly even another field, for example in
subnuclear physics).
Then there is nothing in the world but this field, from which everything is composed - even material formations (eg
particles) are a kind of local "condensation" of this
field ...
Modern unitarization efforts take place on the
ground of quantum field theory and their goal is to unify the fundamental interactions between elementary particles -
the interaction of strong, weak, electromagnetic and
gravitational.
The first significant success on this path
was recorded in the unification of the electromagnetic
interaction and the weak interaction in the so-called electroweak interaction - this is the Weinberg-Salam-Glashow theory. Next unitarizace stage is referred to
as a unification GUT
- (Grand Unification Theory) - here we try to unite the
strong interaction, described by quark chromodynamics, with the
electroweak interaction. These stages of unitarization have
achieved considerable success, leading to the creation of a standard
model of elementary particles (§1.3,
section "Standard model -
unified understanding of elementary particles").
The completion of the unitarization of
interactions in quantum field theory would
consist in the inclusion
of the gravitational interaction, in its unification with the other
three types of interactions. This ambitious unitarization program
is called superunification or supergravity;
at present, work in the field of so-called superstring
theory is being intensified in this direction,
especially in its latest version, the so-called M-theory.
The concept of
unitarization and specific unitary field theory are described in
more detail in Chapter B "Unitary
Field Theory and Quantum Gravity" of the book "Gravity,
Black Holes and the Physics of Specetime",
especially in §B.6 "Unification of
Fundamental Interactions. Supergravity. Superstrings.". The question of where the specific values of the
basic natural constants came from is briefly discussed in §5.5,
passage "Origin of natural constants" of the mentioned monograph.
Our current physical
theories are undoubtedly of limited validity, they are
"preliminary" and temporary, sooner or later they will
be modified and improved. However, some of their aspects already
hide the seeds of the future more perfect theory, perhaps even
the final "theory of everything"..?..
Physics - beauty and adventure of
knowledge
The beautiful and admirable building of physics, which was only
briefly outlined here, with the progress of knowledge allows us
to better understand the structure and functioning of our
world - from microscales of elementary particles,
through the structure of atomic nuclei and atoms, functioning of
living cells, organisms, stars and planets, galaxies, to the
construction and evolution of the entire universe. He gradually
answers the basic question :
" How
does the world around us and within us works ? ".
The scientific knowledge of new,
often previously unsuspected phenomena and the beauty of the
architecture of their mutual relations expressed in the laws of
nature, gives the thoughtful person the infinite joy of
knowledge - "how our world works", what is the
essence things and events. This inner feeling is
spiritual in nature, not unlike the
"religious ecstasy" or samadhi in meditation.
This leads us to a deep respect for the grandeur
of the hidden order and the "reason" that is immanently
embodied in being. Through internally understood scientific
knowledge, we can achieve liberation from the
shackles of pettiness of pride and selfishness, spiritualization
of our understanding of the world, and the ennoble of
our interrelationships with each other and with living and
inanimate nature.
Physically, we humans are just a tiny
powder in the universe. Spiritually, however, we go
far beyond this insignificance of ourselves: the
vast universe - its structure, its functioning, its evolution -
we are able to know and understand him.
However, there is still a lot we
do not yet know and may we have no idea
about are... More adventures of knowledge await
us !
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