Science is the companion of our everyday life. It is
inextricably related to each and every activities of our daily life .Starting
from the toothpaste used in the morning to the day long using of internet,
mobile and watching of television all are the fruits of scientific discovery.
Science has made human life beautiful and prosperous. It has increased comfort
and happiness. However, this development of science was not possible in a day.
Science has reached this stage due to untiring efforts of innumerable scientist
from ancient time. In this chapter we will try to introduce the contribution of
those dedicated scientists by giving a description of a brief but continuous
history of development of physical science especially of physics from ancient
times.
Physics
The branch of science which deals with matter and energy is
called physics. The main objectives of physics are to establish the relation
between matter and energy and to express it quantitatively on the basis of
observation, experimentation and analysis.
Scope of physics
Physics is the key of all science. It is the fundamental
branch of science because the foundation of other subjects is based on the
principles of physics. For example, the principle of conservation of energy is
a basic principle of physics used to explain the wide range of science starting
from the structure of atom to weather forecasting. Starting from Engineering to
Medical Science, Astronomy to Oenology, Biology to Psychology the instruments
of Physics are used.
For the systematic study of physics, we can divide it into
the following branches:
(1) Mechanics
(2) Heat and thermodynamics
(3) Sound
(4) Optics
(5) Electricity and Magnetism
(6) Solid State Physics
(7) Atomic Physics
(8) Nuclear Physics
(9) Quantum Physics and
(10) Electronics
History and development of physics
Modern civilization is the product of science. Behind this
development of science there are untiring efforts, discoveries and innovation
of scientists. Science has no national or political boundaries. The growth,
development and benefit of science are enjoyed by all people of all nations.
From ancient time scientist have been contributing for the development of
science. In this lesson we will try to mention the contributions of physicists.
Thales (624-569 B.C) is famous for his predictions regarding solar eclipse. He
also knew about the magnetic properties of load-stone. Pythagoras (527-497 B.C)
is a memorable name in the history of science. Beside the invention of several
Geometric theorems, he made longer lasting contribution through his works on
vibrating string. He was given several Geometric theorems. Moreover, he made
long lasting contributions through his works on vibrating strings. The present
scales of musical instruments and music are partially the contributions of his
research on the vibration of strings.
Greek philosopher Democritus (460-370 B.C) gave the idea
that the matter consists of indivisible units. He called it atom. His concept
about atom was significant even though it is completely different from the
present concept. Greek scientist Archimedes (287-212 B.C) discovered the
principles of lever and the law of upward force acting on bodies immersed in
liquid and was able to determine the impurity in metals. He also knew the technique
of setting fire by concentrating sun rays with the help of spherical mirrors.
After Archimedes, scientific discoveries advanced rather
slowly for a few centuries. In fact scientific discoveries did not revive in
Europe before the thirteenth century. During this time West European
civilization particularly adopted the trends of the Byzantine and Muslim
civilization in the pursuit of knowledge. The Arabs were also particularly
advanced in Science, Mathematics, Astronomy, Chemistry and Medical Science.
During this time the contribution of Ibne-Al-Haithan (965-1039 A.D) and
Al-Hazen (965-1038 A.D) may be particularly mentioned for their theories of
light, a branch of physics. Ptolemy (127-151 A.D) and other earlier scientists
believed that the eyes itself sends light rays to see an object. Al-Hazen
contradicted this view and asserted that we see an object because light rays
from the object fall on our eyes. Experiments with magnifying glass brought him
near to the modern theory of convex lens. Al-Masudi (896-956 A.D) wrote an
encyclopedia on the History of Nature in which the name of Windmill was first
mentioned. At present many countries of the world produce electricity by using
this windmill.
Roger Bacon (1214-1294 A.D) was the pioneer of the
experimental scientific methods. According to him all scientific truths should
be verified through observations and experiments. At the end of the fifteenth
century, Leonardo de Vinci (1452-1519 A.D) made a model of aero plane by
observing the act of flying of birds. Although he was a painter, he had
considerable knowledge about mechanics. As a result, he was able to invent
efficiently some common instruments. During the Galileo-Newtonian age and even
before that time a few of very important scientists, although small in number
were born. They contributed a lot to the advancement of science too. Dr.
Gilbert (1540-1603 A.D) is unforgettable for his extensive research and theory
on magnetism. Snell (1591-1626 A.D) of Germany discovered the laws of
refraction of light. Huygen (1626-1695 A.D) reviewed the motion of pendulum,
developed the mechanical device of clocks and invented the wave theory of
light. Robert Hook (1635-1703 A.D) strove to find out the elastic properties of
bodies. Robert Boyle (1627-1691 A.D) conducted experiments to find out the
properties of gases at different pressures. Von Guerick (1602-1686 A.D)
invented air pump. Romer (1644-1710 A.D) measured the velocity of light by
studying the eclipse of a satellite of Jupiter, but none of his contemporary
scientist believed that velocity of light could be so high.
Kepler (1571-1630 A.D) presented three laws for a general
mathematical explanation of concept of solar-centered theory of Copernicus.
Kepler’s success was based on his assumption of an elliptical orbit opposed to
the conventional circular orbit. He verified the validity of his mathematical
laws about the orbits of the planets with the data collected through
observation by his teacher Tychobrahe (1546-1601 A.D).
The inception of modern scientific method was made by a
famous Italian scientist Galileo (1564-1642 A.D). He showed for the first time
that the observations, experimentation's and definitions of physical quantities
systematically and the determination of relations among them are the basic
foundation of scientific works. Galileo introduced the scientific trends of
developing mathematical theory and verifying its authenticity through
experiment. Later, Newton (1642-1727 A.D) gave it a complete shape. Galileo
defined displacement, motion, acceleration, time etc. and determined relations
among them. Consequently he discovered the laws of falling bodies and
established the foundation of statics. Newton by his versatile genius
discovered mechanics and the three famous laws of mechanics and law of
universal gravitation. He also made contribution for optics, heat and sound. He
invented calculus, a new branch of mathematics.
The discovery and inventions of the eighteenth and
nineteenth century paved the way for Europe to industrial revolution. The steam
engine of James Watt (1736-1819 A.D) played a vital role for industrial
revolution. Hans Christian Oersted (1777-1851 A.D) demonstrated the magnetic
effect of current. This discovery led Michael Faraday (1791-1867 A.D), Henry
(1797-1879 A.D) and Lenz (1804-1865 A.D) towards discovering the fact that
magnetic effect produces electric current. In fact, this was a discovery of the
process of converting mechanical energy into electrical energy.
In 1864 James Clark Maxwell (1831-1879 A.D) demonstrated
that light is one kind of electromagnetic wave. He established the
electromagnetic theory by combining electric and magnetic field. Similar kind
of radiation was also discovered and produced in 1888 by Heinrich Hertz (1857-1894
A.D). Using the same kind of waves in 1896, Marconi (1874-1937 A.D) discovered
the method of sending signal through ″Morse code″ to far off distance. Before him Sir Jagadish Chandra Basu
(1858-1937 A.D) was able to send energy from one place to another through
electromagnetic wave. In this way radio communication was developed. By the end
of nineteenth century Roentgen (1845-1923 A.D) discovered x-rays and Becquerel
(1852-1908 A.D) discovered the radio activity of uranium.
In the twentieth century surprising advancement took place
in the field of physics. Max Planck (1858-1947 A.D) discovered quantum theory
of radiation. Albert Einstein (1879-1955 A.D) invented theory of relativity.
These two theories not only explained the previous experimental result but also
made some predictions which were experimentally verified. Ernest Rutherford’s
(1871-1937 A.D) nuclear theory regarding atoms and Neill Bohr’s (1885-1962 A.D)
concept of electron layers in the hydrogen atoms were very important step of
atomic physics.
The next important discovery was made in 1938. At this time
Otto Hann (1879-1968 A.D) and Stresemann (1902-1980 A.D) found out that nucleus
was fissionable. Due to fission a nucleus of large mass number splits up into
two nuclei of approximately equal mass number and a part of its mass is
converted into energy as a result of which atom bomb and nuclear reactor are
invented. The amount of energy we are getting at present from the nucleus is
huge compared to the energy obtained from all the sources in the past. Day by
day nuclear energy is becoming the principal source of energy. In this century
quantum theory of the relativity etc. was developed in the field of theoretical
physics. Satyendranath Basu (1894-1974 A.D) professor of physics, University of
Dhaka made important contribution on theoretical physics. He demonstrated a
comparatively correct form of Planck’s quantum theory. His theory is known as
Bose-Einstein’s statistics. As recognition of his contribution one kind of
elementary particle is named after him and is called Boson. Three Nobel
laureate physicist Prof. Abdus Salam (1926-1996 A.D) of Pakistan, Sheldon
Glasso (1932-) and Stevan Wienberg (1933-) of United States made outstanding
contribution by discovering weak electric force in unifying the elementary
particles in unified field theory. Prior to that Nobel laureate physicist
Chandra Shekhar Ramon (1888-1970 A.D) discovered Ramon effect. Physics has made
significant contribution in the progress of medical science in twentieth
century. By using radio isotopes along with the discovery of numerous equipment's
physics has contributed to medical science. Another advancement of physics in twentieth
century is exploration in the space. The contribution of physics lies in
landing human footprint on the moon along with the staying of months after
months in space station and exploration on the Mars.
Artificial satellite has contributed to forecast weather and
made communication easy. Moreover electronics has already brought about
revolution in our daily life and changed our life style. Now a day’s radio,
television, digital camera, mobile phone, i-pad and computer are used almost in
every house. Various electronics instruments have developed human’s work
ability to a great extent.
In nineteenth century physics played a vital role for the advancement
of medical science. Outstanding contribution of physics in the field of medical
science lies in inventing different instrument along with radio isotope for the
prevention of diseases. Another advancement of physics in the twentieth century
is the exploration in the space.
Objectives of Physics
Physics unearths the
mystery of nature: Physics is the fundamental branch of science because its
principles are the basis of other branches of science. For example, the principle
of conservation of energy is a principle of physics used to explain the wide
range of science starting from the structure of atom to weather forecasting.
Although the main function of physics is to study matter and
energy, the main objective of physics is to realize the rules of nature as well
as unearthing the mystery of nature. In the beginning of twentieth century
physicist discovered that electrons revolves around the positively charged
nucleus of atom. Subsequent experiments proved that nucleus consists of protons
and neutrons. Now the physicists have discovered that proton and neutron are
formed of smaller particles.
The study of physics helps not only to understand and
explain the natural events but also its application plays a vital role in other
branches of science. At present physics is at the center probably because of
its application in other branches of science. The discovery of electron at the
end of ninetieth century made possible to invent electron microscope which has
brought about a revolution in material science and Cytology.
In physics there is development of theories and application
mathematics at the same time it has practical application and engineering
application too. Physics is very essential to give fundamental explanation and
form idea about Chemistry, Geology, Astronomy, Meteorology etc. In addition,
there is wide application of methodology and instruments of physics in Biology,
Oceanology, Psychology and Medical Science.
Physics describes the
laws of nature: The natural world that we live in follows some certain laws
e.g. Newton’s law of gravitation, law of conservation of energy etc. Since our
childhood we have been acquiring these laws through our personal experiences
which are very essential for our life. We cannot change the function and laws
of nature but can utilize them. For their proper utilization we need sufficient
knowledge about them. Moreover physics is the science that studies on this
earth for innovation.
Development of
technology results from the proper application of fundamental laws of physics: We
have to have knowledge about the fundamental laws of physics if want to know
how television works, rocket flies
in the space, artificial satellite revolves around the earth, mobile phone functions, submarine
remain submerged into water and how by using internet the whole world can be explored in a moment. The
discovered laws of physics pave the
way to invent these technologies.
Study of physics is a
perfect human training: We can achieve new idea by the study of physics.
Physics instructs on how to think, show
cause, how to put argument, how to utilize logic and mathematics. It stimulates
our imagination and develops the
power of thinking.
Physics teaches how
to carry out observation: We can develop our capability of observation. We
can also learn how to carry out systematic
observations by studying physics properly.
Space and time
In science particularly in physics the concept of space and
time is very important. We need the concept of space and time to describe any
event, because without it we cannot get clear idea about space and time of the
event. The concept of space is in vogue from ancient time to locate the
position of an object and space occupied by it. Similarly the concept of time
is necessary to understand sequence and duration of the event.
Euclid’s concept:
Euclid was fast to present the geometric concept of space.
Galileo’s concept:
Galileo in his book, Statics used space and time in the law of motion and
acceleration. Thus space and time have become very important quantities in
mathematical equations.
Newton’s concept:
The concept of space and time has become clearer and taken quantitative form
through Newtonian mechanics. Space is a three dimensional extension in
Newtonian or classical physics. Space has no beginning or end. It has limitless
extension. Space can be divided into infinite small parts i.e. space is
continuous. Space is homogeneous as regions of any space are identical. Space is
independent. Though all the events take place and spread within the space;
space is never influenced by any object or event. Like space, time is also
independent. So, passage of time cannot change space.
End
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