Evolution of Physics and its

Impact on Society
Fayyazuddin
National Centre for Physics
Quaid-i-Azam University, Islamabad
• “The goal of physics is not only to observe
nature but to understand it. Mathematics is
often the most suitable way to formulate
natural laws, but theoretical systems of
concepts are more essential, and these often
must be adapted as science progress”.
(Heisenberg)
• Modern science is relatively new; its roots date back to the
17th Century. Galileo is regarded as its father. In contrast to
science, technology is very old. The pyramids in Egypt are
one example of ancient technology. Before Galileo, there
were two periods which we must mention in relation to the
development of science.
• Ancient Greeks made remarkable contributions to human
civilization: (philosophy, mathematics, science) introduced
deductive method.
• From axioms which they regarded as a priori, they deduced
results in self consistent manner. Eucledian geometry is one
example of a perfect system. For them, pure thought was
much superior than work with hands. However,
Archimedes’ law on floating bodies was based on
experiment. Greeks also made remarkable contributions to
Astronomy. Aristotle argued that orbit of a planet must be a
circle because circle is a perfect curve.
• When Europe was in dark ages, the Muslim Civilization
was aware of Greek knowledge.
• In the West, the access to Greek knowledge came
through Muslims. [Ibn Sina (Avicenna), Ibn Rushd
(Averros), Ibn al Haitham, Khawarizmi, Al Baruni, Omer
Khayam].
• But Muslim Civilization could not sustain development
of science for a simple reason that although they were
better experimentalists than Greeks they did not go
beyond observations. In general, they did not deduce
scientific principles from observations (a notable
exception is derivation of laws of reflection and
refraction in optics by Ibn al Haitham). They were more
interested in practical applications rather than building
a scientific edifice.
• To build a scientific edifice, it is essential to go
beyond the existing thought. The ruling class
was not prepared to tolerate any thought
which would initiate departure from
orthodoxy prevalent at that time. They have
no problem with practical use of technology
avoiding rational and intellectual aspects of
science and knowledge. As a consequence,
the Muslim contribution to human civilization
declined so rapidly that since 13th century
they had hardly made any contribution to
secular human knowledge.
• For two thousand years, no body challenged the authority of Aristotle. His
law of falling body that a stone weighing for example 100 gms would fall
10 times faster than a stone weighing 10 gm, was first challenged by
Galileo. He performed a simple experiment. He went up to the top of the
leaning Tower of Pisa, dropped two stones weighing 10 and 100 gms and
demonstrated that the two stones fell to the ground practically
simultaneously. From this experiment he deduced the law of falling
bodies. All bodies fall at the same rate in a vacuum and at the end of a
given time, have velocity proportional to time and distance proportional
to square of the time.
• Galileo did not perform the experiment in
vacuum but in air and he went beyond
observation when he enunciated the law of
falling body by adding the word vacuum. The
deduction of scientific law from observations and
experiments is basic to science. Since Galileo was
first to do that, he is rightly regarded as father of
modern science. Galileo also came into trouble
with the Church, when he concluded that Earth is
not at the Centre of Universe. Earth is one of the
planets which revolves around the sun. To save
his skin he renounced his theory and when he
came out of prison, he said “but it still moves.”
• At about the same time, Kepler from large amount of
astronomical data, formulated his famous three laws:
the planetary orbit forms an ellipse (again Aristotle was
wrong); equal areas are swept in equal times; the time
to go around varies as a3/2, where a is the semi major
axis of the ellipse. The year Galileo died, Newton was
born.
• He formulated his three laws of motion in a precise
form. As Weinberg put it, the profound cultural effect
of the work going back to Newton is that nature is
strictly governed by impersonal mathematical laws.
Newton’s Law of gravitation is the first dynamical law.
As every student of physics knows Kepler’s three laws
of planetary motion and Galileo’s law of falling body
are just consequence of Newton’s law of gravitation.
The terrestrial phenomenon of gravitation was unified
with celestial gravitation.
• Newtonian mechanics is a perfect system,
where-ever it is applicable it gives precise
results. But it has its limit of applicability; it
breaks down for bodies travelling with high
velocities comparable to velocity of light and
at microscopic level involving atoms and
elementary particles. The formulation of
Newtonian mechanics by Lagrange and
Hamilton was crucial for the development of
quantum mechanics. We will come to this
point later.
• The development of calculus, essential for describing the motion
was developed both by Newton and Leibniz. Leibniz’s method was
superior to that of Newton. The following observation of Bertrand
Russel is pertinent for the development of science and society:
“The English was misled by patriotism into adhering to his where
they were inferior to those of Leibniz, with the result that after his
death English mathematics was negligible for hundred years. The
harm that in Italy was done by bigotry, was done in England by
nationalism. It would be hard to say which of the two proved the
more pernicious.”
• In 19th century two great conceptual revolutions associated with
Darwin (theory of evolution by natural selection) and Maxwell
(unification of electricity and magnetism) took place.
• Electric environment is manmade. In nature, electricity is seen in
lightening. Certain stones called magnetite exhibit magnetic
properties. Nothing seems to be common between them.
• Basic laws governing electromagnetic phenomena
were formulated (Coulomb, Ampere, Faraday) in 19th
century. Faraday’s law of electromagnetic induction is a
discovery of great importance as it made possible to
generate electricity directly from mechanical energy.
• Electric energy has a great advantage that it can be
transported to homes and is used in numerous ways.
• We live in an environment created by electricity;
entered into the first phase of domestication of
technology.
• Maxwell expressed the basic laws of electromagnetism
in terms of four differential equations. These equations
encompass the whole of electromagnetic phenomena.
It shows the power of mathematics.
• A consequence of Maxwell’s equations is that
electric and magnetic fields propagate through
space as waves with speed of light.
• Hertz experimentally demonstrated the existence
of electromagnetic waves. His work gave stimulus
for practical applications of Maxwell’s equations.
• This is how electronic communication was born:
One of the far reaching impact of Maxwell’s
equations is to give birth to a powerful tool in the
form of electronic media for entertainment, to
shape the opinion of the people for political aims
or ideological indoctrination or for marketing of
products especially by multinationals.
• In order to appreciate how a discovery become useable, I would like
to quote from a play. The Swiss dramatist Friedrich Durrenmatt has
written a play called “Physicists.” The plot as I understand is as
follows:
• A physicist who is a genius made a discovery of great importance.
But has a fear that his discovery may be used for destructive
purpose.
• To escape from the madness of sane people; he pretends to be
insane and takes refuge in an asylum. Later on two more physicists
are admitted in the same asylum. In actual fact they are not insane
but pretend to be so; they are spies sent by two governments to
spy on the first physicist. One of the spies called himself Newton.
When the nurse attending him was about to find out that he is a
fake, he murders her.
• When police came to investigate, the following conversation takes
place between the police inspector Richard and Newton.
• Newton: When you work that switch by the door, what
happens, Richard?
• Inspector: The light goes on.
• Newton: You establish an electric contact. Do you
understand anything about electricity, Richard?
• Inspector: I am not a physicist.
• Newton: I do not understand much about it either. All I
do is to elaborate a theory about it on the basis of
natural observation. I write down this theory in the
mathematical idiom and obtain several formulae.
• Then the engineers come along. They don’t care about
anything except formulae. They simply exploit it. They
build machines – and a machine can only be used
when it becomes independent of the knowledge that
led to its invention.
• So any fool now-a-days can switch on the light or touch
off the atomic bomb. (He pats the inspector’s
shoulders). And that’s what you want to arrest me for,
Richard. It’s not fair.
• At the end of the 19th century and beginning of the
20th century some remarkable experimental
discoveries were made which have a profound effect in
the future development of science and technology.
• Roentgens discovered X-rays in 1895.
• Radioactivity was discovered by Becquerel in 1896.
Radioactivity was extensively studied by Marie and
Pierre Curie, Rutherford and Soddy.
• In 1897, J.J. Thomson discovered the electron – the
first elementary particle.
• The discovery of atomic nucleus was announced by
Rutherford in 1911.
• Neutron was discovered by Chadwick in 1932. Radioactivity
is the only nuclear phenomenon which is found on the
earth. Nuclear environment exists in star. With the
development of nuclear reactors and nuclear weapons an
environment is created by human being”, which is alien for
earth.
• By the turn of 20th century, the basic structure of physics, in
which theories are formulated in terms of differential
equations, predicting the future behavior in terms of states
at a given instant of time was well-established. For the
observable phenomena, the law of causality holds.
• Lord Kelvin pointed out in the basic structure there are
“two clouds at the horizon”, one is failure to detect the
existence of ether by the Michelson – Morley experiment
and the other is inability to use existing theory to explain
energy distribution of black body radiation.
• These two clouds led to two conceptual
revolutions
• Theory of Relativity and Quantum Mechanics
• The credit for the first revolution goes to Einstein.
It changed our concept of space and time.
• The second revolution, Quantum Theory
(Heisenberg, Schrodinger, Dirac) was more
profound.
• It changed our way of thinking not only in physics
but also in chemistry, biology and philosophy.
(Freeman Dyson)
• Determinism of classical mechanics is replaced by
uncertainty principle i.e. when events are examined
closely, uncertainty prevails; cause and effect become
disconnected; causal relations hold for probabilities;
waves are particles and particles are waves; matter
antimatter are created and destroyed (vacuum
polarization); chance guides what happens.
• By unifying special theory of relativity with quantum
mechanics, Dirac predicted the existence of antimatter.
• The unification of terrestrial and celestial gravity by
Newton; the unification of electricity and magnetism
by Maxwell; the unification of geometry with gravity by
Einstein, the unification of special theory of relativity
with quantum mechanics by Dirac were hallmark of
physics.
• In the same context the unification of
electromagnetism with radioactivity was achieved by
Glashow, Salam and Weinberg in the late 1960’s.
• Basics of electroweak unification are:
• Edifice of particle physics is built on following
principles:
• Chiral Fermions: Left handed – Right handed fermions
belong to different representations of gauge symmetry
group, to take into account that weak interactions
distinguish between left and right.
• Local Gauge Invariance: To find appropriate gauge
symmetry group
• Spontaneous breaking of gauge symmetry
• Renomalizability
• Abdus Salam has made significant contributions
in all these fields.
• Gauge Invariance:
• Electric charge is not only conserved, but it also
determines the strength of electromagnetic
interaction.
• The salient features of local gauge invariance are:
Irrespective of nature of particle, the strength of
electromagnetic interaction is determined by the
electric charge.
• Electromagnetic interaction is mediated by
photon, the quantum of electromagnetic field.
Photon is massless and has spin 1 with only
transverse polarization.
• Underlying gauge symmetry group U (1)
• Fundamental constituents of matter are leptons and quarks (spin
½).
• Understanding of fundamental constituents of matter and their
interactions lies in discovering a gauge symmetry group.
• Both electromagnetic current and weak currents are vector in
character, the weak current being V-A to take into account the
violation of discrete symmetries C and P.
• Underlying gauge group for electro-weak Unification (Standard
Model), proposed independently by Salam. Weinberg and Glashow,
is non-Abelian group SUL (2) x UY (1).
• The gauge vector bosons which mediate the electroweak
interactions are photon Aµ, charged vector bosons W±µ and a
neutral vector boson Zµ which mediates the neutral weak
interactions. This was a crucial prediction of the Standard Model of
particle physics.
• All these vector bosons are massless to start
with, as gauge symmetry does not allow the
mass term. Since weak interactions are short
range, to give masses to the weak vector
bosons the gauge symmetry is spontaneously
broken so that weak vector bosons W±µ and Zµ
acquire masses, leaving photon massless as
electromagnet gauge symmetry is exact.
• The masses of vector bosons W±µ and Zµ are
generated by spontaneous breaking of the
gauge symmetry by the Higgs mechanism
which leaves the photon massless.
• The year 1978 saw a remarkable set of experiments
confirming the existence of neutral weak interaction as
predicted by the electroweak theory. Salam, Weinberg and
Glashow were awarded Noble Prize in 1979 for their work.
• The crowning verification of electroweak theory was
achieved in 1980’s, when the vector bosons W± and Z with
masses 80-90 times proton mass were discovered at CERN.
• Discovery of spin zero particle viz Higgs boson (discovered
at LHC in 2012) necessary for spontaneous symmetry
breaking near 125 GeV is a land mark discovery-providing
the last missing link of electroweak theory.
• The masses of vector bosons W±µ and Zµ are generated by
spontaneous breaking of the gauge symmetry by the Higgs
mechanism which leaves the photon massless.
We conclude evolution of physics with the following
remarks:
• Human beings are endowed with two remarkable
qualities – conceptual thought (language including
mathematics) and capacity to invent and use tools.
Both concepts and tools have played an indispensible
role in evolution of physics.
• Unlike goal oriented project, basic research is an
unending project – going from one generation to
another generation.
• It is shared by whole mankind
• With tremendous advance in technology, new tools
became available to explore the universe at large and
at small scales.
• Often hidden mysteries of nature are
uncovered
• Deciphering of these mysteries lead to new
insight in understanding the behavior of
nature. This is the way science progresses.
• In the present century, exploration of the
universe at large scale has uncovered two
mysteries the dark energy and the dark
matter.
• To resolve these mysteries, new insight is
needed about the fundamental constituents
of matter and their interactions.
Impact on Society:
• C.P. Snow in his book “Two Cultures” divides the
industrial revolution in these phases.
• The first phase which began with the invention of
steam engine at the end of 18th century was mainly
created by handy men as C.P. Snow calls them.
• In the second phase of industrial revolution: chemistry
played a major role. Giant chemical companies were
established in Europe and USA.
• In the third phase of industrial revolution atomic
particles like electrons, neutrons, nuclei atoms, atomic
and nuclear radiations played a crucial role. This
revolution is based on physics of 20th century. The birth
of quantum theory in the 20th century had a
tremendous impact on future development.
• It is hard to imagine that without quantum
mechanics, transistors, computer chips and
lasers would have been invented.
• Physicist Freeman Dyson calls the fourth
phase of revolution tool driven revolution.
Scientists develop new tools and computer
software.
• The craftsmanship used in their tools may
initiate new technologies. Two examples: X-
rays and nuclear magnetic resonance ->
Computed Axial Tomography (CAT), Magnetic
Resonance Imaging (MRI).
• The scanning technology revolutionized diagnostic
techniques in medicine.
• It may also lead to some landmark discoveries in basic
sciences. A prime example is the use of X-rays
crystallography to study biological molecules.
• Such a study lead Crick and Watson to unfold the structure
of DNA – the genetic code-perhaps the greatest discovery
in biology after Darwin.
• The subsequent developments in DNA testing, genetic
engineering and bioinformatics had made an enormous
impact on human society.
• Another example is the World Wide Web (WWW)
developed at CERN for basic research, which has
revolutionized the information technology. These
developments resulted in culmination domestication of
technology in terms of internet, computer games and
mobile phones.
• On the other hand tremendous progress in
space technology has been used to put the
probe in outer space to study the structure of
universe.
• We conclude that science has not only made
an enormous impact on human intellect but
has also drastically changed human living.
• Prof. Salam has on many occasions made a
passionate appeal to develop the scientific base
to sustain the modern technologies. Knowledge is
not static; one of the most important purpose of
a university is to keep pace with development of
knowledge. This is best done if one is a part of
this process even if the participation is on a
modest scale. Take as an example, the training of
a physicist. a physicist is trained to observe, to
take data; and in taking data to minimize the
errors. He must be aware of the degree of
accuracy and limitation of his data.
• He is trained to present data in a graphical or
functional form to see any pattern in it,
analyze it and draw inference. Sometime his
data may contradict a known law, he must
reexamine it to see that he may have made
some errors in his measurements or whether
the deviation is significant or it is just due to
systematic and statistical errors. He also learns
to plan and handle experimental apparatus.
He is well versed in applicable mathematics.
• In theoretical physics, the most difficult part is
to express a vague idea in a concrete
mathematical form. Very few problems can be
solved exactly; one is trained to make
appropriate approximations and to discard
some of the parameters which may not affect
the results significantly. Modern day physicist
is well trained to use computer, to solve some
of the problems numerically, to modify the
known programmes or to write a new
programme.
• The basic training of collecting and analyzing
the facts and then to draw conclusions from
them using self consistent and tenable
assumptions is useful whether we adapt or
develop modern technologies based on
modern science. In short education is a
training of mind. But this training must be first
rate whether it is imparted by an “irrelevant”
high energy physicist or by some “relevant”
physicist. There is no substitute for the quality.
• Riazuddin was also conscious of strong academic and
intellectual base for research and development and for
positive change in the fabric of the society. In
Islamabad University (QAU) and NCP, (in the
establishment of which he played a pioneering role),
he tried to make them vibrant centers for teaching and
research with strong emphasis on understanding and
analytical thinking.
• To conclude: Modern technologies cannot be sustained
without an indigenous scientific base. Social and
human capitals are needed to exist as a free nation.
Social capital creates an environment in which science
and technology, art and literature, music and other
cultural activities can flourish. It enhances our vision
and makes us sublime. It keeps darkness in human soul
in a dormant state.
• Human capital is needed to manage and
develop scientific, technological and economic
enterprises. There is no way except through
education to generate this kind of capital.
• Without minimizing the importance of
primary education, higher education and
research in the universities must be
strengthened.
• Only in this way, we can come out of
intellectual and economic colonialism.
• I will end my talk with verses from Iqbal:

Thou didst create night but I made the lamp