INTRODUCTION TO PHYSICS
NATSCI4L
GABE
SEM 02 2024
Physics and Natural Science
Definition of "Physics" by Microsoft Encarta
“A major science dealing with the fundamental constituents of the universe, the forces they
exert on one another, and the results produced by these forces. Sometimes in modern
physics a more sophisticated approach is taken that incorporates elements of the three
areas listed above; it relates to the laws of symmetry and conservation, such as those
pertaining to energy, momentum, charge, and parity.”
What Are the Branches of Physics?
While there are more branches sprouting up as science and technology progresses, there are
generally 11 branches of physics. These are as follows.
1.
Classical Physics - This branch of physics is mainly concerned with the laws of motion
and gravitation as outlined in Sir Isaac Newton and James Clerk Maxwell’s kinetic
theory and thermodynamics, respectively. This branch of physics deals mostly with
matter and energy. Often, physics which date before 1900 are considered classical
physics, whereas physics which date after 1900 are considered modern physics.
In classical physics, energy and matter are considered separate entities. Acoustics,
optics, classical mechanics, and electromagnetics are traditionally branches within
classical physics. Moreover, any theory of physics that is considered null and void in
modern physics automatically falls under the realm of classical physics.
As Newton's Laws are one of the main features of classical physics, let's examine them.
What Are the Three Laws of Physics?
Newton's Laws of Motion (The Three Laws of Physics)
1. Law of Inertia: A body remains at rest or in uniform motion in a straight line unless
acted upon by a force.
2. Force = Mass x Acceleration: A body's rate of change of momentum is proportional to
the force causing it.
3. Action = Reaction: When a force acts on a body due to another body, then an equal
and opposite force acts simultaneously on that body.
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INTRODUCTION TO PHYSICS
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Modern Physics - Modern physics is a branch of physics that is mainly concerned with
the theory of relativity and quantum mechanics.
Albert Einstein and Max Plank were the pioneers of modern physics as the first
scientists to introduce the theory of relativity and quantum mechanics, respectively.
In modern physics, energy and matter are not considered as separate entities. Rather,
they are considered different forms of each other.
What Are the Two Pillars of Modern Physics?
The two pillars of modern physics are as follows.
1.
2.
Albert Einstein's theory of relativity
Max Plank's quantum theory.
What Is the Theory of Relativity?
Albert Einstein's theory of relativity is one of the most important discoveries of the
contemporary age, and states that the laws of physics are the same for all non-accelerating
observers. As a result of this discovery, Einstein was able to confirm that space and time are
interwoven in a single continuum known as space-time. As such, events that occur at the
same time for one observer could occur at different times for another.
Einstein's theory of relativity is summarized in the formula:
E = mc^2
In this equation, "E" represents energy, "m" represents mass, and "c" represents the speed of
light.
What Is Quantum Theory?
Discovered by Max Plank in 1900, quantum theory is the theoretical basis of modern physics
that explains the nature and behavior of matter and energy on the atomic and subatomic
level. The nature and behavior of matter and energy at that level is sometimes referred to as
quantum physics and quantum mechanics.
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INTRODUCTION TO PHYSICS
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SEM 02 2024
Plank discovered that energy exists in individual units in the same way that matter does, rather
than just as a constant electromagnetic wave. Thus, energy was quantifiable. The existence of
these units, called quanta, act as the basis of Plank's quantum theory.
3.
Nuclear Physics - Nuclear physics is a branch of physics that deals with the
constituents, structure, behavior and interactions of atomic nuclei. This branch
of physics should not be confused with atomic physics, which studies the atom
as a whole, including its electrons.
According to the Microsoft Encarta encyclopedia, nuclear physics is defined
as: “The branch of physics in which the structure, forces, and behavior of the
atomic nucleus are studied.”
In the modern age, nuclear physics has become very wide in its scope and has
been applied in many fields. It is used in power generation, nuclear weapons,
medicines, magnetic resonance, imaging, industrial and agricultural isotopes,
and more.
Who Discovered Nuclear Physics?
The history of nuclear physics as a distinct field from atomic physics begins with the discovery
of radioactivity by Henri Becquerel in 1896. The discovery of the electron one year later
indicated that the atom had an internal structure.
With this, studies began on the nuclei of atoms, thus nuclear physics was born.
Nuclear physicists examine only the nucleus, not the atom as a whole.
4.
Atomic Physics - Atomic physics is a branch of physics that deals with the
composition of the atom apart from the nucleus. It is mainly concerned with
the arrangement and behavior of electrons in the shells around the nucleus.
Thus, atomic physics mostly examines electrons, ions, and neutral atoms.
One of the earliest steps towards atomic physics was recognizing that all
matter is composed of atoms. The true beginning of atomic physics is marked
by the discovery of spectral lines and the attempt to explain them. This
resulted in an entirely new understanding of the structure of atoms and how
they behave.
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INTRODUCTION TO PHYSICS
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Geophysics - Geophysics is a branch of physics that deals with the study of
the Earth. It is mainly concerned with the shape, structure and composition of
the Earth, but geophysicists also study gravitational force, magnetic fields,
earthquakes, magma, and more.
Geophysics was only recognized as a separate discipline in the 19th century,
but its origins date back to ancient times. The first magnetic compasses were
made from.
All of these discoveries can be included in the field of geophysics, which is
defined as: "A natural science concerned with the physical processes and
physical properties of the Earth and its surrounding space environment, and
the use of quantitative methods for their analysis."
Computer simulation of the Earth's magnetic field in a period of normal
polarity between reversals.
6.
Biophysics - According to the Microsoft Encarta encyclopedia, biophysics is
defined as: “The interdisciplinary study of biological phenomena and
problems, using the principles and techniques of physics.”
Biophysics studies biological problems and the structure of molecules in living
organisms using techniques derived from physics. One of the most
groundbreaking achievements of biophysics is the discovery of the structure
of DNA (Deoxyribonucleic Acid) by James Watson and Francis Crick.
7.
Mechanical Physics - Mechanical physics is a branch of physics that deals
with the motion of material objects under the influence of forces.
Often called just mechanics, mechanical physics falls under two main
branches:
● Classical mechanics
● Quantum mechanics
Classical mechanics deals with the laws of motion of physical objects and the forces that
cause the motion, while quantum mechanics is the branch of physics which deals with the
behavior of smallest particles (i.e. electrons, neutrons, and protons).
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INTRODUCTION TO PHYSICS
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What Are the Main Branches of Mechanics?
Mechanics can be broken down into eight sub-branches. These are as follows:
1. Applied mechanics
2. Celestial mechanics
3.
4.
5.
6.
7.
8.
Continuum mechanics
Dynamics
Kinematics
Kinetics
Statics
Statistical mechanics
8.
Acoustics - The word "acoustics" is derived from a Greek word akouen,
meaning "to hear."
Hence, we can define acoustics as a branch of physics that studies how sound
is produced, transmitted, received and controlled. Acoustics also deals with
the effects of sounds in various mediums (i.e. gas, liquid, and solids).
9.
Optics - Optics is a branch of physics that studies electromagnetic radiation
(for example, light and infrared radiation), its interactions with matter, and
instruments used to gather information due to these interactions. Optics
includes the study of sight.
The Microsoft Encarta encyclopedia defines optics as: “A branch of physical
science dealing with the propagation and behavior of light. In a general
sense, light is that part of the electromagnetic spectrum that extends from X
rays to microwaves and includes the radiant energy that produces the
sensation of vision.”
Who Invented Optics?
Optics began with the creation of lenses by the ancient Egyptians and Mesopotamians. This
was followed up by theories of light and vision developed by ancient Greek philosophers and
the development of geometric optics in the Greco-Roman world.
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INTRODUCTION TO PHYSICS
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These earlier studies on optics are known as classical optics. Studies that came after the 20th
century, such as wave optics and quantum optics, are known as modern optics.
10. Thermodynamics - Thermodynamics is a branch of physics that deals with
heat and temperature and their relation to energy and work. The behavior of
these quantities is governed by the four laws of thermodynamics.
Who Discovered Thermodynamics?
The field of thermodynamics was developed from the work of Nicolas Léonard Sadi Carnot who
believed that engine efficiency was the key that could help France win the Napoleonic Wars.
The Scottish physicist Lord Kelvin was the first to come up with a concise definition of
thermodynamics. His definition stated :"Thermo-dynamics is the subject of the relation of
heat to forces acting between contiguous parts of bodies, and the relation of heat to
electrical agency."
What Are the Four Laws of Thermodynamics?
The four laws of thermodynamics are as follows.
1. If two systems are in thermal equilibrium with a third system, they are in
thermal equilibrium with each other. This law helps define the concept of
temperature.
2. When energy passes, as work, as heat, or with matter, into or out from a
system, the system's internal energy changes in accord with the law of
conservation of energy. Equivalently, perpetual motion machines of the first
kind (machines that produce work with no energy input) are impossible.
3. In a natural thermodynamic process, the sum of the entropies of the
interacting thermodynamic systems increases. Equivalently, perpetual motion
machines of the second kind (machines that spontaneously convert thermal
energy into mechanical work) are impossible.
4. The entropy of a system approaches a constant value as the temperature
approaches absolute zero. With the exception of non-crystalline solids
(glasses), the entropy of a system at absolute zero is typically close to zero,
and is equal to the natural logarithm of the product of the quantum ground
states.
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INTRODUCTION TO PHYSICS
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SEM 02 2024
11. Astrophysics - The word "astrophysics" is a combination of two Latin-derived
words: astro, which means "star," and phisis, which means "nature."
Thus, astrophysics can be defined as a branch of astronomy which is
concerned with the study of the universe (i.e., stars, galaxies, and planets)
using the laws of physics.
What Is the Difference Between an Astrophysicist and an Astronomer?
Technically speaking, astronomers only measure the positions and characteristics of celestial
bodies, whereas astrophysicists use the application of physics to understand astronomy.
However, the terms are now used interchangeably, since all astronomers use physics to
conduct their research.
Today's technology is so rooted in physics that our way of life depends upon it. The increased
computational power and higher standard of living derived from physics-based technology
allows us to pursue a deeper understanding of physics, again leading to improved
technology—and so on.
Your computer’s microchips were built from transistors using quantum physics. GPS
navigation? Sensitive to nanosecond calculations derived from Einstein's general theory of
relativity. PET scans use 3D body-imaging made possible by particle physics. Even the World
Wide Web serving you this article was a creation of physics—conceived by Tim Berners-Lee at
CERN to transfer large physics data files.
What Can I Do with a Physics Degree?
Professionals with physics degrees are truly versatile. They can hold engineering roles such as
laser, project, research or application engineers. They can also assume computer science
roles like systems analyst, software, systems or test engineer; or, they can inhabit other STEM
roles like an accelerator operator, a physical sciences technician or a science educator on the
middle or high school level.The SPS points out another exciting application: “Physics bachelor’s
work across all branches of the armed forces. Many work in aviation or nuclear power.”
Influence of physics on related disciplines
7 | Introduction to Physics
INTRODUCTION TO PHYSICS
NATSCI4L
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SEM 02 2024
Because physics elucidates the simplest fundamental questions in nature on which there can
be a consensus, it is hardly surprising that it has had a profound impact on other fields of
science, on philosophy, on the worldview of the developed world, and, of course, on
technology.
Indeed, whenever a branch of physics has reached such a degree of maturity that its basic
elements are comprehended in general principles, it has moved from basic to applied physics
and hence to technology.
Thus almost all current activity in classical physics consists of applied physics, and its contents
form the core of many branches of engineering. Discoveries in modern physics are converted
with increasing rapidity into technical innovations and analytical tools for associated
disciplines.
There are, for example, such nascent fields as nuclear and biomedical engineering, quantum
chemistry and quantum optics, and radio, X-ray, and gamma-ray astronomy, as well as such
analytic tools as radioisotopes, spectroscopy, and lasers, which all stem directly from basic
physics.
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