Friday, August 29, 2025

Gravity


Gravity 

     Gravity is the one force of Nature that operates everywhere; it controls the effects of all the other forces wherever they act; it regulates countless natural clocks, from the orbits of planets to the lifetimes of stars. Gravity rules the most violent places in the Universe – quasars, pulsars, gamma-ray bursters, supernovae – and the most quiet – black holes, molecular clouds, the cosmic microwave background radiation.

        Today gravity binds stars and galaxies and clusters of galaxies together, but much earlier it pushed the Universe violently apart. Gravity explains the uniformity of the Universe on very large scales and its incredible variety on small scales. Gravity even laid the path toward the evolution of life itself. If we understand how gravity works, then we begin to understand the Universe.

        Rich as our understanding of the workings of gravity in the Universe has become, it is far from complete. The gaps are not just hidden regions, phenomena yet to be discovered, although when such discoveries occur they are sure to bring more amazement and delight. The most exciting gaps are those in our understanding of the laws of Nature.

How Gravity Evolves?

      Gravity, the oldest force known to mankind, is in many ways also the youngest. It is understood well enough to explain stars, black holes and the Big Bang, and yet in some ways it is not understood at all. Explaining gravity required the two greatest scientific minds of modern history, Isaac Newton and Albert Einstein; and now hundreds of the brightest theoretical physicists are working to invent it once again. Each time gravity has been re-invented, it has sparked a revolution. 

      Newton’s theory of gravity stimulated huge advances in mathematics and astronomy; indeed, it was the beginning of modern theoretical physics. Einstein’s theory of gravity, which he called general relativity, opened up completely unexpected phenomena to investigation: black holes, gravitational waves, the Big Bang. When, sometime in the future, gravity changes into quantum gravity, possibly becoming just one of many faces of a unified theory of all the physical forces, the ensuing revolution may be even more far-reaching.

         Each of these revolutions has built on the previous one, without undermining it. Newton’s gravity is just as important today for explaining the motions of the planets as in Newton’s time. It is used to predict the trajectories of spacecraft and to understand the structure of galaxies. Yet general relativity underpins all of this, because Newton’s gravity is only an approximation to the real thing. We need only Newton to help us understand how a star is born and evolves; but when the star’s evolution leads to gravitational collapse and a supernova, then we have to ask Einstein’s help to understand the neutron star or black hole that is left behind. When we have a theory of quantum gravity, it won’t stop us from using general relativity to explain how the Universe expanded after the Big Bang; but if we want to know where the Big Bang came from, and why (or whether) time itself started just then, we will need to ask the quantum theory.

        There is a deeper reason for this continuity from one revolution to the next. As an example, consider the fact that two of the fundamental ideas in Einstein’s general relativity, called the principle of relativity and the principle of equivalence, originated with Galileo. Einstein’s revolution brought a complete change in the mathematical form of the theory, added new ideas, and opened up new phenomena to investigation. But there was a profound continuity in physical ideas, and these were as important to Einstein as the mathematical form of the theory. The coming quantum revolution will surely likewise be grounded firmly in concepts that physicists today use to understand gravity to investigation. But there was a profound continuity in physical ideas, and these were as important to Einstein as the mathematical form of the theory. The coming quantum revolution will surely likewise be grounded firmly in concepts that physicists today use to understand gravity.


Monday, December 27, 2021

Wormhole Theory

Wormhole Theory


Einstein's theory of general relativity mathematically predicts the existence of wormholes.     

        A wormhole is a theoretical passage through space-time that could create shortcuts for long journeys across the universe. Wormholes are predicted by the theory of general relativity. But be wary: wormholes bring with them the dangers of sudden collapse, high radiation and dangerous contact with exotic matter.

Wormhole theory:

In 1935, physicists Albert Einstein and Nathan Rosen used the theory of general relativity to propose the existence of "bridges" through space-time. These paths, called Einstein-Rosen bridges or wormholes, connect two different points in space-time, theoretically creating a shortcut that could reduce travel time and distance.

Wormholes contain two mouths, with a throat connecting the two. The mouths would most likely be spheroidal. The throat might be a straight stretch, but it could also wind around, taking a longer path than a more conventional route might require.

Einstein's theory of general relativity mathematically predicts the existence of wormholes, but none have been discovered to date. A negative mass wormhole might be spotted by the way its gravity affects light that passes by.

Certain solutions of general relativity allow for the existence of wormholes where the mouth of each is a black hole. However, a naturally occurring black hole, formed by the collapse of a dying star, does not by itself create a wormhole.

Thursday, November 4, 2021

The Feynman Technique

 How to Understand Physics Better?

       The Feynman Technique is one of the best techniques to understand physics better. It was given by American Physicist, Richard Feynman. Richard Feynman is one of the greatest physicists of all the time. He won the 1965 Nobel Prize in Physics for his work on Quantum Electrodynamics (QED). But what made him truly famous was his teaching. Feynman is regarded as the greatest explainer of physics.
         The Feynman Technique can be traced back to Einstein's quote:
"If you can't explain something, you don't understand it well enough."
      If you reverse this quote, it becomes the Crux of the Feynman Technique.
    "To understand something better, explain it simply."
       The Feynman Technique has four Steps:
Step 1) Write the heading of the topic you want to understand on a piece of paper.
Step 2) Explain it by writing in the simplest way possible. Don't just write what the concept is but also try to explain using illustrations and examples.
Step 3) Teach the concept to someone. This is the most important step. Once you are done writing, try to explain it as if you are teaching to a class. One thing you have to make sure is that you don't use complicated language to explain something.
Step 4) Go back to your weak areas. If there was any part in which you struggled in step 3, this means you haven't understand it well. Go back to that weak part and think how you can explain it better. This is the simple trick to improve Step 3. Instead of explaining to a class, try to explain the concept to a kid because a kid who knows very less will often ask you "Why" on many points. The more number of ways you answer, the deeper you drive in the concept and the better you understand it.
   The Feynman Technique has two benefits:
  Firstly, you get to know what you understand the best.
    Secondly, you discover your weak areas. 
     So instead of working on the whole topic, you just have to work on a specific area.
    Feynman Technique is based on teaching and it has been well established that we remember:
10% of what we read
20% of what we hear
70% of what we discuss
95% of what we teach.

                                ........... Zahoor Sir Physics

Tuesday, July 28, 2020

Biography of Michael Faraday

Biography of Michael Faraday
The self-taught scientist who became the father of electricity.

   Although Faraday received little formal education, he was one of the most influential scientists in history becoming the inspiration for likes of Einstein and Tesla. He is best known for the discovery of electromagnetic induction, his invention of the electric motor, contributions to electrochemistry or due to the fact that he was responsible for introducing the concept of field in physics.
   In 1873, the standard unit of electrical capacitance was named farad in his honor. The Bank of England unveiled a £20 bill with his portrait in 1991 as he joined a distinguished group of Britons with their own notes, including William Shakespeare, Florence Nightingale and Isaac Newton. Many claim him the father of electricity and in fact, Maxwell himself had said, "Faraday is, and must always remain, the father of that enlarged science of electromagnetism."

Early Education
  Michael Faraday was born to Margaret and James Faraday on 22nd September, 1791. The family was not well off so they moved to London seeking more opportunities. The young Faraday, who was the third of four children, having only the most basic school education, had to educate himself, while working on the streets of London.
  At the age of 14, Faraday became an apprentice to a local bookbinder and bookseller, George Riebau, in Blandford Street, Marylebone. During his seven years of apprenticeship, Faraday made good use of the priceless access to books which his employment gave him and which his generous employer allowed.
  Faraday was deeply motivated by the book, "Conversations on chemistry" by Jane Marcet so much so that when 20 years old, he attended the lectures by the most renowned English chemist of the time, Sir Humphry Davy. Faraday later on sent Davy a 300-page book based on the notes that he had taken during these lectures. Davy's reply was immediate, kind, and favourable.

The First Invention
   In 1813, when Davy damaged his eyesight in an accident with nitrogen trichloride, he decided to take Faraday as temporary assistant. In the class-based English society, Faraday was not considered a gentleman, because of which, Davy's wife declined to treat Faraday as an equal making his life so miserable that he contemplated suicide.
   But Davy refused to let the talented young man go. He employed Faraday permanently as his scientific assistant much to his wife's displeasure. They went together on a tour of the continent meeting the scientific elite of Europe as well as exchanging ideas with them. Davy joked that his assistant Michael Faraday was his greatest discovery; little did he know that he'd be right!
  In 1820, Danish physicist Hans Ørsted discovered (although by accident) that electric current in a wire could deflect magnetic needle in the immediate vicinity. Davy wasn't bothered the least by it, but Faraday, on the contrary, declared it one of the greatest discoveries of mankind. One year later, Faraday invented the electric motor by using the same principle, which is today the basis of fans, pumps, compressors, elevators, and refrigerators.
   Faraday's rapid rise made Davy jealous and he became indifferent to him, treating him more as a challenger. Towards the end, Davy even accused Faraday of plagiarism causing Faraday to cease all research in electromagnetism until his mentor's death. In 1829, Davy was paralyzed by a stroke and passed away aged 50. Despite the bitter ending, Faraday described Davy fatherlike, kind and protective.

Electromagnetism
  Thus, Faraday began his great series of experiments, in which he discovered the law of electromagnetic induction. The breakthrough came when he wrapped two insulated coils of wire around an iron ring, and found that upon passing a current through one coil, a brief current was induced in the other coil.
    Faraday went on to invent a rudimentary generator in 1831 and as the story is usually told, the prime minister or some other senior politician was given a demonstration of induction by Faraday. When asked, “What good is it?” Faraday replied: “What good is a newborn baby?” Fifty years passed before electric power really took off as envisioned by Faraday.
 Faraday was little interested in mathematics and his own scientific career was characterized by simple ideas and simple experiments. But the discovery of induction was eventually formalized by Scottish physicist and mathematician James Clerk Maxwell into an equation now known as Maxwell–Faraday equation.
  Faraday wrote in a letter to Maxwell, "I was at first almost frightened when I saw such mathematical force made to bear upon the subject, and then wondered to see that the subject stood it so well." The equation by Maxwell became the foundation of power generation hence making Faraday the father of electricity.

Later Life
  After induction, Faraday formulated the laws of electrolysis in 1834 whose applications are far and wide such as production of industrial chemicals and electroplating. For his unprecedented work, Faraday was appointed the Professor of Chemistry at the Royal Institution without a degree. He was also offered a knighthood but he turned it down citing religion.
  In 1836, he invented the Faraday cage, an enclosure used to block the electromagnetic field. You can find a real-life version of Faraday cage right inside your kitchen: the metal shell in the microwave oven acts like a Faraday cage as it prevents the microwaves inside the oven from leaking out. Faraday cages are also used in MRI scans to prevent external frequencies from causing any distortion to the data coming from the patient.
   Beyond his scientific research into areas such as chemistry and physics, Faraday accepted numerous, and often time-consuming, service projects for the greater good of the country. For example, every Christmas, Faraday would give free science lectures to a general audience, including young people, in an informative and entertaining manner.
    He delighted in filling soap bubbles with various gasses in front of his audiences and marveled at the rich colors of polarized lights, but the lectures were also deeply philosophical. In this way, Faraday was really the world's first science communicator. He delivered a total of nineteen such lectures until he was 53 years old.
   Many years after his scientific career, Faraday dedicated a book to George Riebau, his first employer, writing: "...you kindly interested yourself in the progress I made in the knowledge of facts relating to the different theories in existence, readily permitting me to examine those books in your possession that were in any way related to the subjects occupying my attention."

Science and Religion
    Faraday was a devout Christian although there may have been some conflict between his religious beliefs and his activities as a scientist. Many of his colleagues and especially Henry Bence Jones had claimed through letters and writings that Faraday was a scientist first and religious second, but he was also both.
   Jones, who was Faraday's junior, published the book, "The Life and Letters of Faraday", in 1870. Faraday said of himself, "Without experiment, I am nothing. In early life I was a very lively, imaginative person, who could believe in the Arabian Nights as easily as in the Encyclopedia, but facts became more important to me, and saved me. I could trust a fact. One thing is fortunate, which is, that whatever our opinions, they do not alter nor derange the facts of nature."
       Faraday's laboratory journal entry on 19 March, 1849 says, "ALL THIS IS A DREAM. Still examine it by experiments. Nothing is too wonderful to be true, if it be consistent with the laws of nature; and in such things as these, experiment is the best test of such consistency." Faraday viewed his discoveries of nature's laws as part of the continual process of reading the book of nature.
    When asked about his speculations on life beyond death, Faraday replied, "Speculations? I have none. I am resting on certainties. I know whom I have believed and am persuaded that he is able to keep that which I have committed unto him against that day."

Wednesday, July 1, 2020

Edward Witten

 Greatest Living Physicist: Edward Witten

    Edward Witten is Charles Simonyi Professor in the School of Natural Sciences at the Institute for Advanced Study. His work has helped to bridge the gap between mathematics and physics, and he has made important contributions to both fields. He is the only physicist to have won the Fields Medal, one of the highest honors in mathematics. He has played a leading role in developing string theory, an ambitious attempt to extend our understanding of the fundamental forces of elementary particles.
     Witten was born in Baltimore, Maryland, in 1951. He received his Ph.D. in physics from Princeton University in 1976. He was a Postdoctoral Fellow and a Junior Fellow at the Harvard Society of Fellows before becoming a Professor at Princeton University in 1980. He joined the Faculty of the Institute for Advanced Study in 1987, becoming Charles Simonyi Professor in 1997.
      Witten has greatly contributed to the modern interest in superstrings as a candidate theory for the unification of all known physical interactions. In the 1980s, he played an influential role in showing how to derive semirealistic models of particle physics from string theory, and in the 1990s, his work on duality and the strong coupling behavior of string theory had a major impact.
      He is also known for numerous results concerning quantum field theory and the Standard Model of particle physics, sometimes using string theory methods. 
      In mathematics, Witten is known among other things for his novel approaches to Morse theory, the Jones polynomial, and the positive energy theorem of general relativity; for his contributions concerning intersection theory on moduli spaces; and for Seiberg-Witten invariants of four-manifolds and their relation to Donaldson invariants.
      His other honors include a MacArthur Fellowship (1982), the Dirac Prize and Medal of the International Centre for Theoretical Physics (1985), the Dannie Heineman Prize for Mathematical Physics (1998), the Nemmers Prize in Mathematics (2000), the National Medal of Science (2003), the Henri Poincaré Prize (2006), the Crafoord Prize in Mathematics (2008), the Lorentz Medal of the Royal Netherlands Academy of Arts and Sciences (2010), the Isaac Newton Medal of the Institute of Physics (2010), Fundamental Physics Prize (2012), and the Kyoto Prize in Basic Sciences (2014). He is a member of numerous academic societies, including the American Academy of Arts and Sciences, the American Philosophical Society, the National Academy of Sciences, and, as a foreign member, the Royal Society of London and the Académie des Sciences of the Institut de France.

Friday, June 26, 2020

Micheal Faraday

Biography of Micheal Faraday

Quick Info
Born
22 September 1791
Newington Butts, Surrey (now London) England

Died
25 August 1867
Hampton Court, Middlesex, England

Summary
Micheal Faraday was an English physicist whose discoveries in electricity had an enormous influence on the development of mathematics.

BIOGRAPHY
Micheal Faraday did not directly contribute to mathematics so should not really qualify to have his biography in this archive. However he was such a major figure and his science had such a large impact on the work of those developing mathematical theories that it is proper that he is included. We say more about this below.
      Faraday's father, James Faraday, was a blacksmith who came from Yorkshire in the north of England while his mother Margaret Hastwell, also from the north of England, was the daughter of a farmer. Early in 1791 James and Margaret moved to Newington Butts, which was then a village outside London, where James hoped that work was more plentiful. They already had two children, a boy Robert and a girl, before they moved to Newington Butts and Michael was born only a few months after their move.
       Work was not easy to find and the family moved again, remaining in or around London. By 1795, when Micheal was around five years, the family were living in Jacob's Wells Mews in London. They had rooms over a coachhouse and, by this time, a second daughter had been born. Times were hard particularly since Micheal's father had poor health and was not able to provide much for his family.
      The family were held closely together by a strong religious faith, being members of the Sandemanians, a form of the Protestant Church which had split from the Church of Scotland. The Sandemanians believed in the literal truth of the Bible and tried to recreate the sense of love and community which had characterised the early Christian Church. The religious influence was important for Faraday since the theories he developed later in his life were strongly influenced by a belief in a unity of the world.
    Micheal attended a day school where he learnt to read, write and count. When Faraday was thirteen years old he had to find work to help the family finances and he was employed running errands for George Riebau who had a bookselling business. In 1805, after a year as an errand-boy, Faraday was taken on by Riebau as an apprentice bookbinder. He spent seven years serving his apprenticeship with Riebau. Not only did he bind books but he also read them. Riebau wrote a letter in 1813 in which he described how Faraday spent his days as an apprentice.
     After the regular hours of business, he was chiefly employed in drawing and copying from the Artist's Repository, a work published in numbers which he took in weekly. ... Dr Watts's Improvements of the mind was then read and frequently took in his pocket, when he went an early walk in the morning, visiting some other works of art or searching for some mineral or vegetable curiosity. ... His mind ever engaged, besides attending to bookbinding which he executed in a proper manner.
      His mode of living temperate, seldom drinking any other than pure water, and when done his day's work, would set himself down in the workshop ... If I had any curious book from my customers to bind, with plates, he would copy such as he thought singular or clever ...
     Faraday himself wrote of this time in his life:-
Whilst an apprentice, I loved to read the scientific books which were under my hands ...
    From 1810 Faraday attended lectures at John Tatum's house. He attended lectures on many different topics but he was particularly interested in those on electricity, galvanism and mechanics. At Tatum's house he made two special friends, J Huxtable who was a medical student, and Benjamin Abbott who was a clerk. In 1812 Faraday attended lectures by Humphry Davy at the Royal Institution and made careful copies of the notes he had taken. In fact these lectures would become Faraday's passport to a scientific career.
      In 1812, intent on improving his literary skills, he carried out a correspondence with Abbott. He had already tried to leave bookbinding and the route he tried was certainly an ambitious one. He had written to Sir Joseph Banks, the President of the Royal Society , asking how he could become involved in scientific work. Perhaps not surprisingly he had received no reply. When his apprenticeship ended in October 1812, Faraday got a job as a bookbinder but still he attempted to get into science and again he took a somewhat ambitious route for a young man with little formal education. He wrote to Humphry Davy, who had been his hero since he attended his chemistry lectures, sending him copies of the notes he had taken at Davy's lectures. Davy, unlike Banks, replied to Faraday and arranged a meeting. He advised Faraday to keep working as a bookbinder, saying:-
    Science is a harsh mistress, and in a pecuniary point of view but poorly rewarding those who devote themselves to her service.
    Shortly after the interview Davy's assistant had to be sacked for fighting and Davy sent for Faraday and invited him to fill the empty post. In 1813 Faraday took up the position at the Royal Institution.
     In October 1813 Davy set out on a scientific tour of Europe and he took Faraday with him as his assistant and secretary. Faraday met Ampère and other scientists in Paris. They travelled on towards Italy where they spent time in Genoa, Florence, Rome and Naples. Heading north again they visited Milan where Faraday met Volta. The trip was an important one for Faraday.
        These eighteen months abroad had taken the place, in Faraday's life, of the years spent at university by other men. He gained a working knowledge of French and Italian; he had added considerably to his scientific attainments, and had met and talked with many of the leading foreign men of science; but, above all, the tour had been what was most valuable to him at that time, a broadening influence.
         On his return to London, Faraday was re-engaged at the Royal Institution as an assistant. His work there was mainly involved with chemical experiments in the laboratory. He also began lecturing on chemistry topics at the Philosophical Society. He published his first paper in 1816 on caustic lime from Tuscany.
      In 1821 Faraday married Sarah Barnard whom he had met when attending the Sandemanian church. Faraday was made Superintendent of the House and Laboratory at the Royal Institution and given additional rooms to make his marriage possible.
     The year 1821 marked another important time in Faraday's researches. He had worked almost entirely on chemistry topics yet one of his interests from his days as a bookbinder had been electricity. In 1820 several scientists in Paris including Arago and Ampère made significant advances in establishing a relation between electricity and magnetism. Davy became interested and this gave Faraday the opportunity to work on the topic. He published On some new electro-magnetical motions, and on the theory of magnetism in the Quarterly Journal of Science in October 1821. Pearce Williams writes:
     It records the first conversion of electrical into mechanical energy. It also contained the first notion of the line of force.
      It is Faraday's work on electricity which has prompted us to add him to this archive. However we must note that Faraday was in no sense a mathematician and almost all his biographers describe him as "mathematically illiterate". He never learnt any mathematics and his contributions to electricity were purely that of an experimentalist. Why then include him in an archive of mathematicians? Well, it was Faraday's work which led to deep mathematical theories of electricity and magnetism. In particular the remarkable mathematical theories on the topic developed by Maxwell would not have been possible without Faraday's discovery of various laws. This is a point which Maxwell himself stressed on a number of occasions.
     In the ten years from 1821 to 1831 Faraday again undertook research on chemistry. His two most important pieces of work on chemistry during that period was liquefying chlorine in 1823 and isolating benzene in 1825. Between these dates, in 1824, he was elected a fellow of the Royal Society . This was a difficult time for Faraday since Davy was at this time President of the Royal Society and could not see the man who he still thought of as his assistant as becoming a Fellow. Although Davy opposed his election, he was over-ruled by the other Fellows. Faraday never held the incident against Davy, always holding him in the highest regard.
    Faraday introduced a series of six Christmas lectures for children at the Royal Institution in 1826. In 1831 Faraday returned to his work on electricity and made what is arguably his most important discovery, namely that of electro-magnetic induction. This discovery was the opposite of that which he had made ten years earlier. He showed that a magnet could induce an electrical current in a wire. Thus he was able to convert mechanical energy into electrical energy and discover the first dynamo. Again he made lines of force central to his thinking. He published his first paper in what was to become a series on Experimental researches on electricity in 1831. He read the paper before the Royal Society on 24 November of that year.
       In 1832 Faraday began to receive honours for his major contributions to science. In that year he received an honorary degree from the University of Oxford. In February 1833 he became Fullerian Professor of Chemistry at the Royal Institution. Further honours such as the Royal Medal and the Copley Medal, both from the Royal Society, were to follow. In 1836 he was made a Member of the Senate of the University of London, which was a Crown appointment.
      During this period, beginning in 1833, Faraday made important discoveries in electrochemistry. He went on to work on electrostatics and by 1838 he:-
  ... was in a position to put all the pieces together into a coherent theory of electricity.
     The extremely high workload eventually told on Faraday's health and in 1839 he suffered a nervous breakdown. He did recover his health and by 1845 he began intense research activity again. The work which he undertook at this time was the result of mathematical developments in the subject. Faraday's ideas on lines of force had received a mathematical treatment from William Thomson. He wrote to Faraday on 6 August 1845 telling him of his mathematical predictions that a magnetic field should affect the plane of polarised light. Faraday had attempted to detect this experimentally many years earlier but without success. Now, with the idea reinforced by Thomson , he tried again and on 13 September 1845 he was successful in showing that a strong magnetic field could rotate the plane of polarisation, and moreover that the angle of rotation was proportional to the strength of the magnetic field. Faraday wrote:-
    That which is magnetic in the forces of matter has been affected, and in turn has affected that which is truly magnetic in the force of light.
   He followed his line of experiments which led him to discover diamagnetism.
By the mid 1850s Faraday's mental abilities began to decline. At around the same time Maxwell was building on the foundations Faraday had created developing a mathematical theory which would always have been out of reach for Faraday. However Faraday continued to lecture at the Royal Institution but declined the offer of the Presidency of the Royal Society in 1857.
  He continued to give the children's Christmas lectures. In 1859-60 he gave the Christmas lectures on the various forces of matter. At the following Christmas he gave the children's lectures on the chemical history of the candle. These two final series of lectures by Faraday were published and have become classics. The Christmas lectures at the Royal Institution, begun by Faraday, continue today but now reach a much greater audience since they are televised. 
    The Royal Institution literature states:-
    Faraday's magnetic laboratory, where many of his most important discoveries were made, was restored in 1972 to the form it was known to have had in 1854 . A museum, adjacent to the laboratory, houses a unique collection of original apparatus arranged to illustrate the most important aspects of Faraday's immense contribution to the advancement of science in his fifty years at the Royal Institution.
  Martin gives this indication of Faraday's character:-
   He was by any sense and by any standard a good man; and yet his goodness was not of the kind that make others uncomfortable in his presence. His strong personal sense of duty did not take the gaiety out of his life. ... his virtues were those of action, not of mere abstention ...

Thursday, May 28, 2020

The Feynman Technique

How to Understand Physics Better?
       The Feynman Technique is one of the best techniques to understand physics better. It was given by American Physicist, Richard Feynman. Richard Feynman is one of the greatest physicists of all the time. He won the 1965 Nobel Prize in Physics for his work on Quantum Electrodynamics (QED). But what made him truly famous was his teaching. Feynman is regarded as the greatest explainer of physics.
         The Feynman Technique can be traced back to Einstein's quote:
"If you can't explain something, you don't understand it well enough."
      If you reverse this quote, it becomes the Crux of the Feynman Technique.
    "To understand something better, explain it simply."
       The Feynman Technique has four Steps:
Step 1) Write the heading of the topic you want to understand on a piece of paper.
Step 2) Explain it by writing in the simplest way possible. Don't just write what the concept is but also try to explain using illustrations and examples.
Step 3) Teach the concept to someone. This is the most important step. Once you are done writing, try to explain it as if you are teaching to a class. One thing you have to make sure is that you don't use complicated language to explain something.
Step 4) Go back to your weak areas. If there was any part in which you struggled in step 3, this means you haven't understand it well. Go back to that weak part and think how you can explain it better. This is the simple trick to improve Step 3. Instead of explaining to a class, try to explain the concept to a kid because a kid who knows very less will often ask you "Why" on many points. The more number of ways you answer, the deeper you drive in the concept and the better you understand it.
   The Feynman Technique has two benefits:
  Firstly, you get to know what you understand the best.
    Secondly, you discover your weak areas. 
     So instead of working on the whole topic, you just have to work on a specific area.
    Feynman Technique is based on teaching and it has been well established that we remember:
10% of what we read
20% of what we hear
70% of what we discuss
95% of what we teach.

                                ........... Zahoor Sir Physics

Gravity

Gravity        Gravity is the one force of Nature that operates everywhere; it controls the effects of all the other forces wherever they ac...