Some of the most profound statements on the nature of science have come from Albert Einstein, one of the greatest scientists of all time. What do you think did Einstein mean when he said: “The most incomprehensible thing about the world is that it is comprehensible”?

Explanation:

When Albert Einstein said, “The most incomprehensible thing about the world is that it is comprehensible,” he was expressing a profound observation about the nature of the universe and the human capacity to understand it. This statement reflects Einstein’s marvel at the fact that the laws of physics, which govern the behaviour of the cosmos, can be grasped and described by human intellect through scientific inquiry. Here are a few interpretations of what Einstein might have meant by this statement:

• Order in the Universe: Einstein may have marvelled at the inherent order and regularity found in the natural world. Despite the immense complexity of the universe, there are discernible patterns and laws that can be expressed through mathematical equations and understood by human minds.
• Predictability and Rationality: The “comprehensibility” Einstein refers to could be the predictability and rationality of the physical world. The fact that natural phenomena can be predicted and explained with a high degree of accuracy is remarkable, considering the vastness and intricacy of the universe.
• Human Capacity for Understanding: Einstein might be emphasizing the remarkable capability of the human mind to comprehend and model the fundamental principles of the universe. The fact that our intellect, through scientific inquiry, can uncover the secrets of the cosmos is a testament to the power of human reason.
• Unity of Knowledge: Another interpretation is that Einstein was struck by the unity of knowledge—the idea that seemingly disparate phenomena in the universe are interconnected and governed by a small set of fundamental principles. This unity allows scientists to develop a coherent and comprehensive understanding of the world.
• Philosophical Reflection on Science: Einstein’s statement might also reflect a philosophical perspective on the nature of science. The idea that the universe is comprehensible raises questions about the relationship between the human mind and the external reality it seeks to understand.

Einstein’s statement encapsulates a sense of awe and wonder at the fact that the universe, with its vastness and complexity, can be understood and described by the human mind. It underscores the deep connection between the structure of the cosmos and the intellectual capacities of humanity. This sentiment aligns with Einstein’s belief in the elegance and beauty of the laws of physics, as well as his conviction that scientific theories should be as simple as possible but not simpler—a principle often attributed to him.

The whole of physical world is highly complex in nature. The biological world has its own complexities. Moreover, vastly different orders of magnitudes are involved in space, time and mass. Inspite of all this variation, almost all the physical phenomena can be expressed (comprehended) in terms of few basic laws. When viewed in this context, Einstein’s statement “The most incomprehensible thing about the world is that it is comprehensible” becomes very clear.

“Every great physical theory starts as a hearsay and ends as a dogma”. Give some examples from the history of science of the validity of this incisive remark.

Explanation:

The statement “Every great physical theory starts as a hearsay and ends as a dogma” reflects the idea that scientific theories often begin as innovative ideas or hypotheses that challenge existing beliefs but may eventually become widely accepted and entrenched as established dogma. Here are some examples from the history of science that illustrate the validity of this remark:

Copernican Revolution (Heliocentrism):

• Hearsay: Nicolaus Copernicus proposed the heliocentric model, suggesting that the Earth and other planets revolve around the Sun.
• Dogma: Initially, the heliocentric model faced strong opposition from the prevailing geocentric view. Over time, as evidence accumulated and observations supported the heliocentric model, it became widely accepted.

Quantum Mechanics:

• Hearsay: The development of quantum mechanics in the early 20th century challenged classical physics and introduced concepts like wave-particle duality and indeterminacy.
• Dogma: Initially, the probabilistic and counterintuitive nature of quantum mechanics faced resistance and skepticism. However, experimental successes and predictive power eventually led to its widespread acceptance.

Theory of Evolution:

• Hearsay: Charles Darwin proposed the theory of evolution by natural selection, suggesting that species evolve over time through mechanisms like natural selection.
• Dogma: The theory of evolution faced strong opposition from religious and scientific communities. However, with the accumulation of evidence from palaeontology, genetics, and other fields, evolution became a foundational concept in biology.

Theory of Relativity:

• Hearsay: Albert Einstein’s theories of special and general relativity challenged classical notions of space, time, and gravity.
• Dogma: Initially, these theories faced skepticism, but experimental validations, such as the bending of starlight during a solar eclipse, confirmed their predictions, leading to widespread acceptance.

Plate Tectonics:

• Hearsay: Alfred Wegener proposed the theory of continental drift, suggesting that continents were once part of a supercontinent (Pangaea) and have since drifted apart.
• Dogma: Initially met with skepticism, the evidence supporting plate tectonics, including geological and paleontological data, eventually led to its acceptance in the Earth sciences.

Big Bang Theory:

• Hearsay: The Big Bang theory proposed that the universe originated from an extremely hot and dense state and has been expanding ever since.
• Dogma: Initially met with resistance, observational evidence such as the cosmic microwave background radiation and the redshift of distant galaxies strongly supported the Big Bang theory, leading to its widespread acceptance.

Germ Theory of Disease:

• Hearsay: The germ theory proposed by Louis Pasteur and others suggested that microorganisms cause infectious diseases.
• Dogma: Initially faced skepticism, but experimental evidence and advancements in microbiology supported the idea that microorganisms play a crucial role in the spread of diseases.

These examples highlight the common pattern in the history of science where novel and initially controversial ideas, referred to as “hearsay,” eventually gain acceptance as a scientific consensus, becoming “dogma” in the sense that they represent established and widely accepted knowledge within the scientific community. The process often involves a combination of empirical evidence, experimental confirmation, and theoretical coherence that gradually persuades the scientific community to adopt new paradigms.

“Politics is the art of the possible”. Similarly, “Science is the art of the soluble”. Explain this beautiful aphorism on the nature and practice of science.

Explanation:

The aphorism “Science is the art of the soluble” reflects the essence of the scientific endeavour, emphasizing the focus on solving problems and finding answers to questions within the realm of what is feasible and accessible through scientific methods. This phrase captures several key aspects of the nature and practice of science:

• Problem-Solving Orientation: Science is fundamentally about addressing questions, solving problems, and unravelling mysteries about the natural world. Scientists engage in the pursuit of knowledge with a problem-solving mind set, seeking to understand phenomena and find solutions to questions posed by nature.
• Empirical and Practical Approach: The term “soluble” implies that science is concerned with questions that can be addressed empirically and practically. Scientific investigations are rooted in the collection of evidence, experimentation, and observation, leading to solutions that are grounded in real-world observations and measurements.
• Feasibility and Accessibility: The phrase underscores the idea that scientific inquiries are bounded by what is feasible and accessible. Scientists focus on questions that can be addressed using available resources, technology, and methodologies. This practical approach acknowledges the limitations and constraints inherent in scientific exploration.
• Pragmatism in Scientific Research: The term “art” in this context refers to the skillful and creative application of scientific methods. Scientists must exercise judgment and ingenuity to design experiments, formulate hypotheses, and interpret results. The art lies in choosing meaningful and approachable scientific questions.
• Incremental Progress: Science often progresses incrementally, with researchers tackling one soluble problem at a time. This cumulative approach to knowledge allows for the steady advancement of understanding, as each solved problem contributes to a broader understanding of the natural world.
• Applicability and Relevance: The focus on solubility implies a commitment to producing knowledge that is applicable and relevant. Scientific discoveries are not merely intellectual exercises but are often driven by the desire to address practical challenges, improve technologies, or enhance our understanding of the world for the betterment of society.
• Scientific Realism: The aphorism reflects a form of scientific realism, acknowledging that science is concerned with tangible, solvable problems rather than purely speculative or abstract inquiries. It aligns with the view that scientific theories and models should have empirical relevance and be testable.
• Adaptability and Evolution of Knowledge: The nature of scientific inquiry allows for the evolution of knowledge as new problems are identified and solved. The art of the soluble implies adaptability, with scientists adjusting their focus based on the changing landscape of questions and challenges.

“Science is the art of the soluble” encapsulates the pragmatic, problem-solving, and empirical nature of scientific inquiry. It speaks to the essence of science as a disciplined yet creative pursuit, where researchers navigate the boundaries of what is feasible, endeavouring to solve problems that contribute to our understanding of the natural world and its phenomena. This aphorism captures the dynamic and practical spirit of the scientific enterprise.

Politician use all possible ways to achieve their goals. They do not follow any principle, discipline, or norm. They tend to remain in power by any means, fair or foul. But science is a systematized study of observation. A patience is very key factor in the study of science. Sometimes it may take long period to arrive at conclusion. Tycho Brahe worked for twenty long years to make observations on planetary motions. Based on these observations Kepler formulated his laws of planetary motion. Similarly almost all the physical phenomena can be expressed (comprehended) in terms of few basic laws. In science various phenomena are related, they are soluble and can be explained with similar or the same laws. Hence we can conclude that “Politics is the art of the possible”. Similarly, “Science is the art of the soluble”.

Though India now has a large base in science and technology, which is fast expanding, it is still a long way from realising its potential of becoming a world leader in science. Name some important factors, which in your view have hindered the advancement of science in India.

Explanation:

While India has made significant strides in science and technology, there are several factors that have posed challenges and hindered the country’s progress toward realizing its full potential as a world leader in science. Some important factors include:

• Investment in Research and Development: India’s investment in research and development (R&D) as a percentage of GDP has historically been lower compared to leading scientific nations. Adequate funding is crucial for supporting scientific infrastructure, attracting top talent, and conducting cutting-edge research.
• Education System Challenges: The education system in India faces challenges in terms of quality and accessibility. There is a need for reforms in science education at various levels to foster critical thinking, creativity, and a research-oriented mind set.
• Brain Drain: India has experienced a significant brain drain, with a large number of talented scientists and researchers choosing to pursue opportunities abroad. Retaining and attracting skilled professionals to contribute to the country’s scientific advancements remains a challenge.
• Bureaucratic Hurdles: Bureaucratic processes and red tape can slow down decision-making and hinder the efficient utilization of resources in scientific research and development. Streamlining administrative procedures is essential for fostering a more conducive research environment.
• Interdisciplinary Collaboration: While there are notable achievements in specific scientific disciplines, fostering interdisciplinary collaboration has been a challenge. Greater integration between different scientific fields can lead to holistic solutions and innovations.
• Industry-Academia Collaboration: The collaboration between academia and industry in India has room for improvement. Strengthening partnerships between research institutions and industries can enhance the translation of scientific discoveries into practical applications, fostering innovation and economic growth.
• Infrastructure and Facilities: While there has been improvement, certain scientific domains in India still face challenges in terms of access to state-of-the-art infrastructure and research facilities. Continued investment in building and maintaining cutting-edge facilities is crucial for advancing scientific research.
• Science Communication and Outreach: There is a need for better science communication and outreach efforts to create public awareness and appreciation for scientific endeavours. A scientifically literate society is essential for fostering support and interest in research.
• Gender Disparities: Gender disparities persist in the field of science, with women being underrepresented in certain scientific disciplines. Addressing gender bias and creating a more inclusive environment is vital for unlocking the full potential of the scientific workforce.
• Global Collaboration: While India has been increasingly engaging in international collaborations, further strengthening global partnerships can facilitate knowledge exchange, access to international research networks, and participation in large-scale collaborative projects.
• Publication Metrics and Evaluation Criteria: The evaluation criteria for academic and research performance, including an overemphasis on publication metrics, can sometimes hinder innovative and exploratory research. A more balanced approach to evaluation is needed to encourage a broader spectrum of scientific contributions.

Addressing these challenges requires a concerted effort from the government, academic institutions, industry, and the scientific community. By strategically addressing these factors, India can create an environment that fosters scientific excellence, innovation, and sustainable growth in the field of science and technology.

No physicist has ever “seen” an electron. Yet, all physicists believe in the existence of electrons. An intelligent but superstitious man advances this analogy to argue that ‘ghosts’ exist even though no one has ‘seen’ one. How will you refute his argument?

Explanation:

The analogy between electrons and ghosts, while intriguing, is not a valid comparison when it comes to the scientific understanding of these phenomena. The belief in electrons is grounded in a well-established scientific framework supported by empirical evidence and experimental observations, whereas the belief in ghosts lacks similar scientific substantiation. Here are several points to refute the analogy:

• Observable Effects vs. Lack of Evidence: Physicists believe in the existence of electrons because their effects are observable and measurable. The behaviour of electrons can be studied through experiments, and their presence leaves distinct traces. In contrast, the existence of ghosts is typically asserted without empirical evidence or observable effects.
• Experimental Verification: The existence of electrons is supported by a wealth of experimental data from various branches of physics, including electromagnetism, quantum mechanics, and solid-state physics. Experiments involving electric currents, particle accelerators, and electronic devices provide direct and indirect evidence for the behaviour of electrons. In contrast, claims about ghosts lack empirical validation through controlled experiments.
• Consistency and Predictive Power: The concept of electrons is an integral part of scientific theories that demonstrate a high degree of consistency and predictive power. The theories that incorporate electrons, such as quantum mechanics and electromagnetism, have withstood rigorous testing and have successfully predicted a wide range of phenomena. Belief in electrons is grounded in the reliability and accuracy of these scientific theories. Ghosts, on the other hand, lack such a theoretical foundation and predictive power.
• Quantifiability and Precision: The properties and behaviour of electrons can be precisely quantified and described using mathematical models. The precision and accuracy with which the behaviour of electrons can be predicted and measured contribute to the credibility of the electron model. Ghosts, being entities often associated with the supernatural or paranormal, lack such quantifiable properties and consistent descriptions.
• Reproducibility: Experiments related to electrons are reproducible, meaning that different scientists, using similar methodologies, can independently verify the results. The reproducibility of experimental findings adds a layer of reliability to the scientific understanding of electrons. Claims about ghosts often lack the repeatability and consistency that characterize scientific investigations.
• Scientific Methodology: The acceptance of electrons within the scientific community is based on the rigorous application of the scientific method. This involves formulating hypotheses, conducting experiments, collecting data, and subjecting findings to peer review. The belief in electrons is a product of a systematic and evidence-based approach. Claims about ghosts often rely on anecdotal accounts and subjective experiences rather than systematic scientific investigation.

While the analogy attempts to draw a parallel between belief in electrons and belief in ghosts, the scientific basis for these beliefs differs significantly. The belief in electrons is grounded in empirical evidence, experimental verification, and the consistent application of scientific principles, whereas belief in ghosts often lacks these foundational elements. Drawing such distinctions is crucial in maintaining the integrity and reliability of scientific knowledge.

Heikegani is a crab species native to Japan that has shells that bear a pattern resembling the face of a samurai.
Provided below are possible explanations of this phenomena. Which according to you is a more logical and scientific explanation?
(a) A tragic sea accident several centuries ago drowned a young Samurai. As a tribute to his bravery, nature through its inscrutable ways immortalised his face by imprinting it on the crab shells in that area.
(b) After the sea tragedy, fishermen in that area, in a gesture of honour to their dead hero, let free any crab shell caught by them which accidentally had a shape resembling the face of a Samurai. Consequently, the particular shape of the crab shell survived longer and therefore in course of time the shape was genetically propagated. This is an example of evolution by artificial selection.
[Note: This interesting illustration taken from Carl Sagan’s ‘The Cosmos’ highlights the fact that often strange and inexplicable facts which on the first sight appear ‘supernatural’ actually turn out to have simple scientific explanations. Try to think out other examples of this kind],

Explanation:

Argument (b) is more logical and scientific. Because the conclusion is obtained by observing the phenomenon carefully. The conclusion can be verified by anyone.

The more logical and scientific explanation for the Heikegani crab shells bearing a pattern resembling the face of a samurai is option (b): “After the sea tragedy, fishermen in that area, in a gesture of honour to their dead hero, let free any crab shell caught by them which accidentally had a shape resembling the face of a Samurai. Consequently, the particular shape of the crab shell survived longer and therefore, in the course of time, the shape was genetically propagated. This is an example of evolution by artificial selection.”

This explanation aligns with the principles of evolution by artificial selection, where humans intentionally choose certain traits for breeding. In this case:

• Cultural Influence: The fishermen, out of respect for the fallen samurai, released crabs with shells resembling a samurai’s face. This cultural practice led to the selection of specific traits in crab shells.
• Genetic Propagation: Over time, the released crabs with samurai-like shell patterns had the opportunity to reproduce and pass on their genetic traits to the next generation. This process, over many generations, resulted in a higher prevalence of the distinctive shell pattern.
• Natural Selection: The continued release of crabs with this specific shell pattern, coupled with a cultural preference for not harvesting crabs with the samurai-like pattern, allowed these traits to persist over time. This is an example of how human influence (artificial selection) can lead to patterns resembling natural selection.

This explanation is in line with scientific principles and provides a plausible account of how the unique shell pattern in Heikegani crabs could have originated and been maintained over generations. It illustrates how seemingly mysterious or supernatural phenomena often have rational and scientific explanations grounded in observable processes and human interactions with the environment.

The industrial revolution in England and Western Europe more than two centuries ago was triggered by some key scientific and technological advances. What were these advances?

Explanation:

• The rise of modern science and the industrial revolution in Western Europe and England are closely connected to each other. The industrial revolution resulted in public support and interest in science.
• The steam engine played a very important role in the Industrial Revolution in England. The steam engine developed by James watt is an application of heat and the concept of thermodynamics. The steam engine is used to drive machinery, railways, and ships.
• The invention of the flying shuttle by John key and power loom by Cartwright revolutionized the textile industry.
• The setting of blast furnace helped in converting low-grade iron into steel. Steel has wide industrial and structural applications.
• Humphrey Davy discovered a safety lamp which was very useful in mining.
• The Concept of electricity was used to design dynamos and motors.
• The study of gravitation and Newton’s laws of motion helped in designing guns and canons.
• These developments in technology gave power in the hands of Western countries and they ruled over the rest of the world.
• These were a few examples of scientific breakthroughs that helped England and Europe to have an industrial revolution and have their prominent positions in the world.

It is often said that the world is witnessing now a second industrial revolution, which will transform the society as radically as did the first. List some key contemporary areas of science and technology, which are responsible for this revolution.

Explanation:

The scientific breakthroughs in 18^th Century helped England and Europe to have industrial revolution and have their prominent positions in the world. This industrial revolution can be considered as the first industrial revolution.

Some key areas of technology and science, which are mainly responsible for a new industrial revolution taking place now and likely to take place in the near future are:

• Design of super-fast computers.
• Artificial Inteligence
• Biotechnology.
• Development of super-conducting materials at room temperature.
• Advancements in the field of electronics, information technology and nanotechnology, and space sciences.
• Use of LASER technology in surgeries and metal forming..

Write in about 100 words a fiction piece based on your speculation on the science and technology of the twenty-second century.

Explanation:

• In 22^nd century people will be completely dependent on technology for doing everyday work.
• The Mobile phones will be powerful as high end computers.
• Apps will be available for almost all routine works.
• Economy and transaction will be cashless.
• Development of new technologies in genetic engineering and biotechnology which is capable of production of man, animals and plants with specific characters and development of high yielding variety of plants. Cloning of animals will be easy. By changing genes responsible for ageing, periodically ageing problem can be eliminated.
• Tele transportation of physical things will be possible.
• We will be in contact with aliens and have established human settlements outside the earth as well.  We will be having friendly space flights and good relations with other planets in other solar system inhabiting living beings.
• Transportation facilities with high speed will be available.
• By catching brain waves communication will be made without speaking.
• Almost all diseases are curable.

Attempt to formulate your ‘moral’ views on the practice of science. Imagine yourself stumbling upon a discovery, which has great academic interest but is certain to have nothing but dangerous •consequences for the human society. How, if at all, will you resolve your dilemma?

Explanation:

A scientist aims at truth and work for it. A scientific discovery reveals a truth of nature. Hence any discovery, good or bad for mankind, must be made public. Before disclosing it the scientist must ascertain the degree of good or bad consequences it will have on the society. But it should not stop him from disclosing it. If it is seen that discovery is bad for the society, then it is best to keep it limited only to the knowledge of the scientist and researches working on it. A discovery which appears dangerous today may become useful to the mankind some time later. In order to prevent misuse of scientific technology, we must build up a strong public opinion.

Enrico Fermi, the Italian-born Nobel Prize-winning physicist, developed and carried out an experiment of nuclear fission. Now this experiment is a boon for mankinfd because it gave a new source of energy which can be used for developmental purposes. At the same time it is curse, because same concept was used to develop atom bomb which destroyed two cities namely Hiroshima and Nagasaki in the Second World War. The invention is not bad, but its use decides whether it is a boon or a curse.

Science, like any knowledge, can be put to good or bad use, depending on the user. Given below are some of the applications of science. Formulate your views on whether the particular application is good, bad or something that cannot be so clearly categorised:

View With Explanations:

• Mass vaccination against smallpox to curb and finally eradicate this disease from the population. (This has already been successfully done in India.) : Good, because it helped in eradicating a dreaded disease from the Earth.
• Television for the eradication of illiteracy and for mass communication of news and ideas: Good, because it helps in literacy campaign and is an effective method of mass communication and entertainment.
• Prenatal sex determination: Bad, because it leads to the practice of abortion in the case of a female foetus.
• Computers for the increase in work efficiency: Good, because it increases work efficiency.
• Putting artificial satellites into orbits around the Earth: Good, because it helped in the worldwide communication process.
• Development of nuclear weapons: Bad, because these weapons are used and may be used for destructive purposes.
• Development of new and powerful techniques of chemical and biological warfare:  Bad, because these techniques may be used for destructive purposes.
• Purification of water for drinking: Good, because pure water supply will improve the health of people.
• Plastic surgery: It cannot be classified as either good or bad. It is useful to remove certain types of deformations in needy persons. But plastic surgery for cosmetic purposes is not good. It may be used by criminals to change their facial structures so that they can hide from law enforcement authorities.
• Cloning: Cloning is bad because it has the potential to destroy the normal family life of human society. It may be used by criminals, dictators to clone themselves.

India has had a long and unbroken tradition of great scholarship in mathematics, astronomy, linguistics, logic, and ethics. Yet, in parallel with this, several superstitious and obscurantist attitudes and practices flourished in our society and unfortunately continue even today among many educated people too. How will you use your knowledge of science to develop strategies to counter these attitudes?

Explanation:

In order to popularize scientific explanations of everyday phenomena, mass media like internet, newspapers, television, and radio should be used. Knowledge of science should be used to educate the masses so that they learn about the real causes of phenomenon on scientific basis allowing their superstitious beliefs be removed. 

Though the law gives women equal status in India, many people hold unscientific views on a woman’s innate nature, capacity and intelligence; and in practice give them a secondary status and role. Demolish this view using scientific arguments, and by quoting examples of great women in science and other spheres; and persuade yourself and others that, given equal opportunity, women are on par with men.

Explnation:

There is no difference in the capacity of women and men as far as work, intelligence, decision making is concerned. Thus gender does not make women inferior to men. The nature makes little difference in their anatomy and feeling of men and women. The nutrition content of prenatal and postnatal diet contributes a lot towards the development of human mind. If equal opportunities are afforded to both men and women, then the female mind will be as efficient as male mind.

The list of great women who have excelled in their respective fields is very large. The list includes Kalpana Chawla (Astronaut), Sarojini Naidu (Freedom fighter), Madame Curie (Scientist), Indira Gandhi (Politician), Margaret Thatcher (Politician), Benazir Butto (Politician) Mother Teresa (Social worker), Florence Nightingale (social worker) drawn from fields varying from science to sociology are very well-known to the world. Reflecting the contribution being made to each and every sphere of life in the country, it can be positively debated that women are no less essential to society than men.

“It is more important to have beauty in the equations of physics than to have them agree with experiments.” The great British physicist P.A.M. Dirac held this view. Criticize this statement. Look out for some equations and results in this book which strike you as beautiful.

Explanation:

Mathematics is a language of physics. The aim of physics to give qualitative and quantitative treatment i.e., any derived relation or equation must be verified through experimentation. Most of the equations of physics are simple, small and symmetrical and can be verified experimentally. Examples of such equations are E = mc² , E = hv, F = mg, P.E = mgh, etc. There are some equations of Quantum Mechanics and Theory of Relativity, which are highly cumbersome and difficult to understand, yet they agree with the experiments.

Though the statement quoted above may be disputed, most physicists do have a feeling that the great laws of physics are at once simple and beautiful. Some of the notable physicists, besides Dirac, who have articulated this feeling are Einstein, Bohr, Heisenberg, Chandrasekhar, and Feynman. You are urged to make special efforts to get access to the general books and writings by these and other great masters of physics. Their writings are truly inspiring.

Explanation:

General books on Physics make an interesting reading. Books like ‘Surely you are joking, Mr Feynman’ by Richard Feynman are interesting books which should be read by the students who have a keen interest in the department of physics. These not only generate the interest but also teaches you path breaking laws of physics were evolved from a very basic incident. Some other interesting books are: Physics for the Inquiring Mind by EM Rogers; Physics, Foundations and Frontiers by G. Gamow; Thirty Years That Shook Physics by G. Gamow; Physics Can Be Fun by Perelman.

Textbooks on science may give you the wrong impression that studying science is dry and all too serious and that scientists are absent-minded introverts who never laugh or grin. This image of science and scientista is patently false. Scientists, like any other group of humans, have their share of humorists, and many have led their lives with a great sense of fun and adventure, even as they seriously pursued their scientific work. Two great physicists of this genre are Gamow and Feynman. You will enjoy reading their books listed in the Bibliography.

Explanation:

We can cite the example of many scientists who were fun loving, adventurists, jovial. One can add the name of C.V. Raman who enjoyed music in addition to doing serious scientific works and so was Homi Jahagir Bhaba.

Related Topics:

• 1.1.1 What is physics?
• 1.1.2 Scientific Methods
• 1.1.4 Physics and Other Sciences

For More Topics in Physics Click Here

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The selection and testing of superior recombinants involve picking up the better ones from the entire crop plants. The collected germ-plasm is now evaluated to identify the plants showing the desirable combination of characters. Selfing the selected plant for several generations to obtain the homozygous inbred pure line. Such selected homozygous inbred pure line plants are used in the process of the next step called hybridization. There are two types of selections: Natural selection and Artificial selection. With respect to crop improvement, we use artificial selection.

Natural Selection:

It is a natural process and operates in nature without human interference. According to Darwin’s principle “Survival of the fittest”, nature itself selects the fittest organisms. Thus, natural selection favours those characters which are essential for the survival of a species.

Artificial Selection:

Artificial selection can be defined as to choose certain individual plants for the purpose of having a better crop from a mixed population where the individuals differ in characters.

Types of Artificial Selection:

Mass Selection:

This is the most common and old method of crop selection. This method of selection depends mainly on the selection of plants according to their phenotype and performance. In this selection, a large number of similarly appearing vigorous plants are selected for the desired trait and their seeds are mixed together. This mixture of seeds is a mass, and, therefore, it is known as mass selection. The seeds are used for cultivation of the next generation. It is useful in the cultivation of cross-pollinated plants such as maize, watermelon, radish, grapes, apples, onion, pear, etc. This method is used to improve the overall population by positive or negative mass selection. Mass selection is only applied to a limited degree

Advantages of Mass Selection:

• Varieties developed by this method have wide adaptability, wide genetic base and stable.
• It is rapid, simple and least expensive of all plant-breeding procedures. It doesn’t require any scientific knowledge.
• It retains considerable genetic variability.
• It is useful in meeting the need of the farmers
• It is the only method for improving local or wild varieties.

Disadvantages of Mass Selection:

• Variation exists in variety developed by mass selection. The phenotype of these varieties is not as uniform as pure line varieties.
• The selected character of crop exhibit segregation due to natural cross-pollination. Without progeny testing selected types will show segregation in the next generation, hence a test of homozygosity of plants progeny is always required.
• There is less improvement in the crop as compared to pure line selection. The yield depends on the environment.
• Limited use in the improvement of self-pollinated crops.
• Varieties are difficult to identify in the seed certification program than pure lines.
• It is only effective for characters with high heritability.
• Only those varieties which show genetic variation can be improved by this method, as it uses variability present in the population.
• It cannot bring any new change in the genotype.
• There is no control over pollination, which causes greater heterozygosity and as a result the desirable qualities gradually diminish. Also, the pollination may be both by superior and inferior pollens.

Pure Line or Single Plant Selection:

The pure line is the progeny of a single self- fertilized self-pollinated homozygous plant. It can be defined as the process of isolating a desirable homozygous individual from the mixed population and multiplying the same without contamination to release as a new variety. In pure line selection, large numbers of plants are selected from a self-pollinated crop and are harvested individually. The plants with the desired trait or traits are selected out of the variable population in the field. Seeds from selected plants and sown separately to produce progeny by self-pollination. This process is continued for many generations and plants with inferior characters are eliminated in each generation.

Wheat varieties like Kalyan – 27 and PV – 18 are developed by this method.

Advantages of Pure Line Selection Method:

• It is easier than hybridization and requires less skill.
• Due to extreme uniformly, it is easily identified in seed certification and is more supported by farmers and consumers.
• It achieves the maximum possible improvement over the original variety.
• The selected plant shows the desired character for several generations.

Disadvantages of Pure Line Selection Method:

• It is not useful in cross-pollinated crops because it is expensive, laborious.
• The breeder has to devote more time to pure line selection than mass selection. Thus it is time-consuming and laborious. It may take 10-12 years for the development of the new variety.
• There is an upper limit on the improvement in the new variety by the genetic variation present in the original population.
• The new variety doesn’t have wide adaptability and stability in production.

Clonal Selection:

A variety that is propagated vegetatively (asexual reproduction) from a single plant is called clone. Besides clonal selection, interspecific hybridization and mutation breeding are also used for the improvement of asexually propagated crops. These methods have been successfully used in sugarcane and potato.

Advantages of Clonal Selection:

• It is the only method to improve clonal crops.
• The desired clone can be obtained in less than 1 year.
• As there is no danger of deterioration due to segregation and recombination., varieties obtained are as stable as pure lines and easy to maintain.
• It helps in eliminating unproductive and undesirable types.
• This method is useful in conserving hybrid vigour for several generations.

Disadvantages of Clonal Selection:

• This method is applicable only to vegetatively propagated crops.
• In this method, no new genetic variability can be created.

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