Physics is the most basic discipline in the field of Natural Sciences, which also includes other disciplines, such as chemistry and biology. The word Physics comes from a Greek word “Fusis” which means “nature”. An ancient Greek philosopher Aristotle introduced this word in the year 350 B.C. In the Sanskrit language, the meaning of physics is “Bhautiki” that refers to the study of the physical world.
A precise definition of this discipline is as:
Physics is a fundamental branch of science that deals with the study of ‘nature’ and ‘natural phenomenon’. In other words, physics is a branch of science that studies the basic laws of nature and their manifestation in different natural phenomena. It is the backbone of study of life as well as the strength of all other branches of natural science. The fundamental goal of physics is to look for and understand the basic laws of nature on which all the physical phenomena depend.
Table of Contents
Physics studies about how things work, and why things occur the way they do. For example, physics explains about
- Why does a teaspoon gets hot when it is in the cup of tea?
- What is the universe made of and how does work?
- Why sky is blue?
- Why are rainbows having colors?
- What atoms and nuclei are made of?
Physics explains the answers to all these and many more questions related to life, the universe, and everything in the world using basic laws and fundamental principles. One who studies physics is called a physicist.
The creator of the universe has given us things in two forms: matter and energy. Matter refers to anything that occupies space and has mass. It is the material that builds up the physical world around us. It can occur in various states, such as solid, liquid, gas, and plasma, depending on the arrangement and motion of its constituent particles.
Everything which is not material in nature like light, heat, sound, waves, etc. are called energy. Thus, we can say that Physics is the branch of natural science that studied about ‘matter’ and ‘energy’ and their interconversion.
Role of Physics in Different Sectors
Physics plays a vital role in all the sectors for sustainable growth of the globe. There are the following sectors from which we may link to the physics. They are as:
- Health
- Energy
- Technology
- Environment
- Communication
- Bioscience
- Space science
- Education
- Transport
- Meteorology
- Entertainment and many more
Let’s understand a few of them one by one with the help of example.
Health:
Physics plays a significant role in understanding and improving various aspects of health and medicine. It has revolutionized medical diagnosis, treatment, and research, making better healthcare. The cure of many diseases is possible by new innovative methods like the use of X-rays, laser, spectrometers, ultrasound, computed tomography (CT), etc. Physics plays an important duty in radiation oncology, where high-energy radiation is used to treat cancer.
Energy:
It is said that energy is the lifeline of the society. Physics is the major contributor to this sector. It discovered all forms of energy, whether conventional or non-conventional energy. Solar energy, wind energy, and geothermal energy will replace conventional forms in the new millennium. Development of solar cells, wind mills, etc. are the main contributors in this field.
Communication:
Physics plays a vital role in the field of communication network. Development of mobile phones, computer, fax, audio and video transmission and reception, internet services, etc. have made communication both useful and fast.
Bioscience:
Physics has added a new dimension to the study of bioscience. The use of spectrometer, ultrasound, X-rays, EMR, ESR, and MRI have transformed the face of bioscience.
Space science:
The study of physics only made it possible for the launching of rockets, satellites, and all different kinds of space crafts.
Principal Thrusts in Physics
There are two principal thrusts in physics. They are as:
- Unification
- Reduction
We use both of these principles in Physics. So, let’s understand it one by one with example.
(1) Unification: The word ‘unify’ means reduce to unity. The process of uniting is called unification. In physics, it is possible to explain different physical phenomena (which are not similar in nature) in terms of a few concepts and laws. For example, the law of gravitational force given by Newton states the force of attraction between two material bodies.
The same law can be used to describe the free fall of an apple to the ground, the motion of the moon around the earth, the motion of planets around the sun, or the motion of an electron around the nucleus of an atom.
Similarly, the basic laws of electromagnetism (Maxwell’s equations) explain most of the electric and magnetic phenomena. The ultimate attempt of physics is to unify all the fundamental forces of nature into unity. Here, we are attempting to say that all the available forces in nature are children of a single mother force and this theory is known as unified field theory.
(2) Reductionism: The analyzing more complex things in terms of its simple constituents is called reductionism and is the heart of physics. Let’s understand it with the help of an example. Microscopic quantities such as pressure, volume, temperature, etc. explain the state of a gas. We know the gas equation PV = RT, where R is a universal gas constant. We can also express the pressure P of the gas in terms of motion of molecules of gas as P = ρν‾2/ 3. In this formula, ν‾2 is the mean square velocity of the molecule, which is microscopic quantity. This way of expressing a microscopic quantity (pressure of gas) in terms of a microscopic quantity (velocity of molecule) is called reductionism.
Classification of Physics
The extent of knowledge available on physics is so broad. That’s why, as a matter of convenience, it has been divided into two categories. They are:
- Classical (old) physics
- Modern physics
(a) Classical physics: The physics prior to 1890 is considered as classical physics. It includes the study of mechanics, gravitation, heat, sound, light, electricity, and magnetism. The law of motion and gravitation given by Newton had provided a solid foundation of mechanics to the impressive height.
The four laws of thermodynamics and kinetic theory of matter had provided a satisfactory explanation in understanding of energy conservation and the direction of heat flow. James Clerk Maxwell gave the theory of electromagnetic radiation and described all electrical, magnetic, and optical phenomena.
Classical physics cannot work with microscopic particles (e.g. atoms) or objects travelling at very high speed. Therefore, modern physics comes into the existence. However, classical physics correctly and precisely explained the behaviour of the physical world except for the microscopic particles and objects travelling near the speed of light.
(b) Modern Physics: The physics after 1890 is considered as modern physics. It deals with the study of quantum mechanics, relativity, atoms, nuclei, elementary particles like electron, proton, and condensed matter. After 1900, there had been tremendous advances in physics, which gave birth the several new concepts. Roentgen discovered X-rays in 1895.
A few weeks later, Henry discovered the radioactivity. In the year 1897, a professor of physics at the University of Cambridge in England, J.J. Thomson discovered the first subatomic particle called electron. In 1901, Max Planck gave the quantum theory. This theory states that energy is not radiated continuously, but in discrete packets of energy called quanta. Eventually, these quanta came to be known as photons.
In 1905, Albert Einstein proposed a special theory of relativity which gave a new concept to atomic and nuclear physics. In short, the discovery of new theory in the modern physics, after 1890, gave several new concepts to the entire physics.
Physics in Relation to Science
We know that physics is a basic science that tells about the nature of basic things, such as motion, force, energy, matter, light, sound, heat, and the inside of atoms. Apprehension of science starts with the understanding of physics. In this section, we will understand how physics is related to other science subjects.
(1) Physics and Mathematics: We have seen that physics depends of the experimental observations and quantitative measurements. Once we have measured, we need mathematics to express the quantity. The laws of physics are usually expressed as mathematical equations. Therefore, we require a considerable knowledge of mathematics. This shows that physics and mathematics are very closely related.
(2) Physics and Chemistry: The branch of science, chemistry tells how atoms combine to form molecules and how molecules combine to make up the many kinds of matter around us. In order to describe these concepts, we will have to apply the laws and theories of physics. Eventually, it reveals us how physics is related to chemistry.
(3) Physics and Biology: Biology is more complex because it involves matters that are alive. Biological studies are impossible without a microscope invented by the aid of physics. The discovery of radioactivity, X-rays, etc. in physics has cured the number of diseases by improving the method of diagnosis. Without inventions of some electronic equipments like amplifiers, cathode-ray oscillograph, etc. ECG (Electrocardiogram), EEG (Electro Encephalogram) and EMG (Electromyogram) would have been just impossible.
(4) Physics and Other Sciences: As physics is a fundamental of natural science, its laws and theories are applied to explain various concepts, processes in biophysics, meteorology, geophysics, oceanography, material science, etc.
Physics and Technology
Both physics and technology differ from each other. Physics provides the knowledge of material universe, whereas technology transfers the knowledge of physics into practical use. For example, physics has offered the knowledge of semiconductors, but technology used it to build up transistor, diodes, IC, LED, etc. Several technologies have been developed based on the knowledge of physics. A few of them are mentioned below:
Link between technology and physics:
| Technology | Scientific Principle(s) |
|---|---|
| 1. Aeroplane | Bernoulli’s principle in fluid dynamics |
| 2. Computers | Digital logic |
| 3. Electric generator, electric motor, transformer | Faraday’s law of electromagnetic induction |
| 4. Electron microscope | Wave nature of electrons |
| 5. Steam engine | Laws of thermodynamics |
| 6. Hydroelectric power | Conversion of gravitational potential energy into electric energy |
| 7. Lasers | Light amplification by stimulated emission of radiation |
| 8. Nuclear reactor | Controlled nuclear fission |
| 9. Optical fibres | Total internal reflection of light |
| 10. Particle accelerators | Motion of charged particles in electromagnetic fields |
| 11. Photocell | Photoelectric effect |
| 12. Radio and television | Generation, propagation, and detection of electromagnetic |
| 13. Rocket propulsion | Newton’s law of motion |
| 14. Sonar | Reflection of ultrasonic waves |
| 15. Non-reflecting coatings | Thin film optical interference |
The above list of table shows that how the knowledge of physics is important in developing new technologies.
Physics and Society
The discoveries of laws and theories of physics have made the technologies advanced. The advancement of technology completely changed the human lives. For example, we travel faster than ever before in aeroplanes, use electricity to operate numerous electrical appliances, solve complex problems at amazing speed using computers, and many more. Thus, physics set the future of human society.
In this tutorial, we have discussed the definition of physics, its roles in different sectors, classification, and relation with other sciences. Hope that you will have understood the basic points and enjoyed this tutorial.
Thanks for reading!!!
