Scientist Niels Bohr (1885 – 1962)

The man to present the first ever model of an atom, the fount of knowledge, Niels Henrik David Bohr was born on October 7, 1885 in Copenhagen, Denmark. His father Christian Bohr was a professor of physiology at Copenhagen University. His mother Ellen Adler Bohr came from a wealthy Jewish family prominent in Danish banking and parliamentary circles. Niels was born in his maternal family home in ‘King Georg’s Palace’, considered to be one of the prominent and majestic private homes of Copenhagen.

Niels Bohr had primary, secondary and university education in Copenhagen. He was a brilliant and industrious student. He and his younger brother Harold were good football players. They were proud members of the Danish football team. In the Scandinavian state too, they were considered as leading players. It is said that if you ask a Danish citizen about his pride in the four best things of Denmark, he would say: its prosperous shipbuilding industry, her prosperous dairy and cheese industry and her two prodigious sons – the famed artist Hans Christian Andersen and country’s greatest scientist Niels Bohr. The Danish Science Society had awarded a gold medal to Bohr for ingenious study of surface tension. His brother Harold became a great mathematician later.

In 1911, Bohr completed his doctorate in physics. Then he went to London and under the able guidance of Sir J J Thomson, the ‘Father of Electron’, he started research at the Cavendish Laboratory. He then worked with Ernest Rutherford at Manchester for about four years. They remained good friends throughout their lives. Bohr even named his son Ernest after his dear friend. In 1913, Bohr presented his basic theory of the internal structure of an atom. Later, it underwent lot of changes and transformations over a period known as Bohr’s atomic model or Bohr’s theory of atom. This theory became very useful in the fields of chemistry and atomic science. Thanks to this theory that today so much development has taken place in the field of atomic energy.

An atom is the smallest particle of an element that exists freely and takes part in a chemical reaction. Atoms of same or different elements combine to form molecules. Molecules form a solid or liquid or gas depending upon the intermolecular strength or force and conditions like temperature and pressure. An atom is made of two parts. Its core is known as nucleus which contains all the positive charge in the atom and almost all the mass of the atom. The electrons move at high speed in circular orbits around the nucleus. This is known as Bohr model of the atom. It can be compared to the solar system. In the solar system, the sum is at the centre and the planets and asteroids revolve around the sun in the specific orbits. Atom is very small. The diameter of atom’s nucleus is supposed to be 100000th part of an atom’s diameter. Electrons revolve around it at high speed. Hydrogen is the lightest element among all the natural elements. Its nucleus contains only one proton. It carries positive charge. An electron is electrically equal – same as that of the proton, but negative in charge. A proton is 1836 times heavier than an electron. In the hydrogen atom there is only one proton with one electron. The next lightweight element is helium. Its nucleus has two protons and two neutrons. Two electrons move around the nucleus. Uranium is the heaviest of all natural elements. It has 92 electrons, which revolve in 7 different orbits around the nucleus. Thus, in each element the number of protons and neutrons differs.

Bohr, with the help of his atomic model and planck’s quantum theory, was able to explain the stability of the atom and the origin of atomic spectra. Normally, electrons revolve in their own assigned orbits in an atom. But when electricity or energy is passed trough an atom, the electrons quickly change their orbits and jump into a higher orbit. It returns to its original position in a short while. When electron moves to higher orbit it consumes energy and on its return, it releases energy. This release of energy is normally in the form of electromagnetic radiations. Bohr determined the atomic structure of matter by calculating the wavelength of the radiation produced during this process.

Bohr’s work provided a major breakthrough in atomic physics. It dawned a new era in science. Bohr received the Nobel Prize for physics nine years after his wonderful discovery, in 1922. At 37 years of age, he was the youngest physicist to receive this honour. Prior to this achievement, he was appointed chairman at the Copenhagen based Institute of Theoretical physics. In a small country like Denmark, scientist from all over the world would gather at Copenhagen due to Bohr. Einstein had spoken the truth when he asked as to what would have been the state of atomic knowledge, had Bohr not been there.

In 1939, a young Austrian Jew lady, Lise Meitner and her nephew Otto Robert Frisch came to Denmark from Nazi-infested Germany. They were appointed as researchers at Bohr’s institute to an article announcing that German scientists were working on their latest inventions and were planning to divide the nucleus of uranium into two equal parts. Bohr saw that if this was made possible, then immense energy could be produced during the process. It was also possible that Germans could use this technology to be powerful enough to destroy the world. Bohr rushed to America with this information. He discussed and deliberated on the issue with scientists Albert Einstein and Enrico Fermi. Fermi was working on this subject at Columbia University. It did not take much time for these eminent scientists to realize how dangerous it would be for the future of the world. The picture was very clear in their minds. Thereafter, America produced atom bombs and dropped them on two Japanese cities, Hiroshima and Nagasaki, to end the World War II.

Bohr immediately returned to Denmark after deliberations in America. In April 1940, Germany attacked and captured Denmark, sending the king behind bars and stripping the army off weapons. They had planned to kill 6000 Jews living in Denmark. But about 5000 of them safety sailed to Sweden, thus failing the German plan. Niels Bohr, the son of a Jewish mother and his wife Margrethe Norlund were rescued in the dead of night, by the Danish resistance movement in a fisherman’s boat to reach Sweden safely. Nazis raiden Bohr’s residence, but fortunately, they could not lay their hands on the gold medal awarded as the Nobel Prize. Later, Bohr reached America and joined his son Aage, then working as a research physicist at Los Alamos in a nuclear project.

Bohr returned to Copenhagen after the end of the World War II. He was deeply saddened by America’s attack on Japan. He advocated ban on nuclear explosion at international level. Bohr attended the peace conference at Geneva in 1955 as chairman of Denmarks Atomic Energy Commission. He was elected chairman of the conference. In October 1957, Bohr received the $ 75000 Atoms for peace Award from Ford. Bohr received the highest number of awards and medals in the world of science. Among his other researches, his work on the liquid drop model to explain nuclear properties and the principle of complementarity have played an important role in the development of modern physics.

In his last years Bohr tried to point out ways in which the idea of complementarities could throw light on many aspects of human life and thought. He had a major influence on several generations of physicists, deepening their approach to science and to their lives. Bohr himself was always ready to learn. He drew strength from his close personal ties with his co-workers, his sons, wife and brother. Profoundly Danish firmly rooted in his own culture. This was symbolized by his many public roles, particularly as president of the Royal Danish Academy from 1939 until the end of his life. He died in Copenhagen on November 19, 1962.

Sir James Chadwick (1891-1974)

James Chadwick, the discoverer of neutron, a constituent of the nucleus of an atom, was born in Manchester, England on October 20, 1891. He was the eldest son of J J Chadwick. After completing his schooling from the local school he joined the famed Victoria University in Manchester. He acquired his post-graduate degree in 1911. He received a scholarship and went to Charlotenberg, Germany for further study in 1913. Chadwick studied under Hans Geiger at the Technische Hochschule, Berlin. When the World War I broke out in 1914, the Germans captured him and sent him to a labour camp. There was some solace when he met some scientists there and discussed problems in science with them. Thus, he continued his studies mentally on the subject of his interest. When the war ended, he returned home in 1919.

Around the time of his return to Manchester, Lord Rutherford had for the first time made it possible to separate hydrogen and oxygen through artificial transformation. He worked with Rutherford for a while and then got on with his research. But in 1921, when Rutherford succeeded sir J J Thomson as professor of physics at Cavendish Laboratory, he invited Chadwick to join him. Chadwick accepted it happily. First of all, he completed his thesis and submitted it to the University. In 1921, he received doctorate from Cambridge University. He took up lectureship at Cavendish Laboratory and also assisted Rutherford in his research. What happens if the nucleus of an atom of an element is bombarded with high energy alpha particles? Can some new element be found out by doing so? He got down to solving these mysteries. He also wanted to know the structure and size of the nucleus. In 1922, Rutherford and Chadwick discovered ‘proton’ when they bombarded alpha particles on nitrogen nucleus. In 1925, Chadwick married Eileen Stuart Brown of Liverpool. The same year he was appointed assistant director at the laboratory.

In 1920, Scientist Williams Hawkins had predicted the presence of a neutral particle in a nucleus. Many years later, Chadwick discovered this particle called the neutron. For this, Chadwick was awarded the Nobel Prize for Physics in 1935. During the same year, he resigned from Cambridge due to different of opinion with Rutherford on building a new device called cyclotron. He then joined Lavon Jones Institute in Liverpool University as Professor and built the first cyclotron in UK. In the wake of World War II in 1939, it was decided to bring both British Atomic Project and America’s Project at Manhattan together. In 1941, as part of the British Project, he joined the Tube Alloys Project. Two years later, he went to America, He became the scientific advisor to the American-British-Canadian Policy Committee at Oakridge. He was also associated with Robert Oppenheimer’s team working at Los Alamos, New Mexico, USA. This team was working to produce an atomic bomb to end the war.

July 16, 1945 was set for the test of the atomic bomb. The bomb was planet on a 32 ton 100 feet tower erected at Gyro Hill- Alamogordo air base in the desert 120 miles southeast of Albuquerque, New Mexico. At 5.30 in the morning, at a control room, 9 miles (14.5 kms) away from the site, in the presence of about 100 scientists a robot pressed the button. An immense fireball rose in the air. The blast was so loud that it was heard 450 miles away in Taxas. The smoke covered the area of 7 miles. The tower has melted with the heat energy produced. The test was declared successful and the scientist’s job was over. On August 6, 1945, the first atom bomb was dropped on the Japanese city of Hiroshima. In a short while, around 6000 people were killed, 40000 were rendered blind and 20000 gradually became the victims. The entire city had turned into a big graveyard. The second atom bomb was dropped on Nagasaki on August 9, 1945. Japan immediately surrendered and World War II came to and end.

Many atomic scientists believe that such use can only cause mass destruction and unhappiness. Scientists believe that this demon can be tamed and used constructively, to make life happy and prosperous in this world. By 1945, Chadwick was known all over the world as an extraordinary, cultured and self-possessed man. He was also known as a calm, composed and selfless scientist. The British government conferred knighthood on him and appointed him the National Science Advisor. He also served as the British representative to the American Atomic Energy Commission.

Besides his being awarded the Nobel Prize in 1935 for the discovery of the neutron, many international universities and scientific institution honoured him. In 1946, he received the Merit Medal of the USA. In 1950, the Royal Society of England conferred on him the Copley Medal. Franklin Institute, Philadelphia awarded him the Franklin Award. The American Physics Society and other reputed institutions offered him honorary membership. Since 1957 he was associated with the United Kingdom Atomic Energy Institute as part-time member.

Many reputed science periodicals and journals published his articles and research papers. He also wrote on radiation in several magazines and reputed newspapers. These were very informative and useful for scientists, science teachers and the public, at large. In 1930, in collaboration with Lord Rutherford and Sir Charles Ellis he wrote a reference book titled ‘Rays Emanating from Radioactive Substances’. The revised edition was published in 1933. On July 24, 1974, at Cambridge, Cambridgeshire, England, this great scientist passed away at 84. May his invaluable contributions be used for constructive purposes in this world. It is only the future that can reveal whether this discovery of nuclear energy would be beneficial or detrimental to the world.

Scientist James Chadwick photo

Lord Ernest Rutherford (1871-1937)

Ernest Rutherford was born on August 30, 1871 in the southern island of Nelson, in New Zealand. His parents belonged to the Scottish farming community of England and had migrated to New Zealand in 1842. They were cultured and well educated. In 1889, Ernest won a scholarship to Nelson College, a secondary school, where he was a popular boy. Another scholarship allowed him to enroll in Canterbury College, from where he graduated with a BA in 1892 and an MA in 1893 with first-class honours in mathematics and physics.

In 1895, Cambridge University announced scholarships for deserving students of British Commonwealth countries. This was a big break. Rutherford joined Cavendish Laboratory and started research. He was fortunate enough to get guidance from a genius like J J Thomson. It was the time when the sensational discovery of X-rays was just announced. This inspired Rutherford to work on it. Later on, he was attracted towards radioactivity. Thomson invited him to conduct research on the effects of X-rays on gases. Rutherford accepted the challenge happily and began the research. Thomson was already a world-renowned physicist and his assistant Rutherford was a brilliant researcher. Thomson considered Rutherford his best and most talented student. Rutherford concentrated on Becquerel’s discovery of some mysterious and unknown rays. He found out that just as X-rays ionize the gases, these unknown rays (radioactive rays) ionize the gases.

Meanwhile, a new post of professor of physics was created at McGill University at Montreal, in Canada. Thomson could not think of a better choice than Rutherford for the post. He inspired Rutherford to join the place. Rutherford was reluctant to leave a reputed place like Cavendish Laboratory, but to satisfy his guide’s desire he left for Canada in 1898. Here, he studied Becquerel rays under the effect of electric and magnetic fields. He made a wonderful discovery that these rays consisted of three types of rays, alpha, beta and gamma rays. He also succeeded in identifying two types: The radioactive rays that could be blocked by a thick paper were alpha rays (positively charged) and the ones that could be blocked by thin aluminium foil were beta rays. Beta rays were negatively charged electrons. Besides, he came to know that gamma rays were very powerful like X-rays. Here, he got an opportunity to work with the great English chemist Frederick Soddy (Nobel Prize winner for Chemistry in 1921). Rutherford and Soddy then investigated three groups of radioactive elements-radium, thorium and actinium. They concluded in 1902 that radioactivity was a process in which atoms of one element spontaneously disintegrated into atoms of an entirely different element, which also were radioactive. This interpretation was opposed by many chemists who held firmly to the concept of the indestructibility of matter; the suggestion that some atoms could tear themselves apart to form entirely different kinds of matter was to them a remnant of medieval alchemy.

In 1907, Rutherford got an opportunity to return to England. There was a vacancy worth his caliber at Manchester University. He joined here and continued research in radioactivity. In 1908, Rutherford was awarded the Nobel Prize for Chemistry for his research on radioactivity and nucleus of the atom, though he was a well-known professor of physics. The British government knighted him and he became Lord Rutherford of Nelson. He was thus honoured for his outstanding contribution in scientific research.

Another favourite student of J J Thomson, C T R Wilson was awarded the Nobel Prize for Physics in 1927 for his invention of the cloud chamber named after him. Rutherford used this equipment to study alpha rays more closely. He carried out many experiments on scattering of alpha particles by this foils of metals. On the basis of his experimental results, he announced in 1911 that the nucleus of an atom contained all the positive charge, which caused the alpha particles to divert their path as they approached the nucleus. Rutherford was then hailed as the discoverer of proton, the positively charged particle in the atom. It was Rutherford who discovered that an atom had a dense and massive positively-charged nucleus with the light negatively-charged electrons revolving around it. The simplest and lightest atom was that of hydrogen, with only one electron. In 1919, Rutherford proposed that the positively charged particle in the nucleus of hydrogen atom is a proton. These particles are present in the nuclei of all elements. The mass of a proton is 1836 times more than that of an electron. Like an electron, proton is also an elementary particle. Though proton is quite heavy than electron the electrical charge on both is equal but of opposite types. The mass of a proton is 1.6726231 X 10 -27 kg and proton’s electrical charge is 1.602.X 10 -19 coulomb.

Rutherford’s celebrated students include Henri Moseley and Niels Bohr. It was thanks to the joint efforts of Rutherford and Bohr that the clear structure of the stom emerged. In 1919, Rutherford was appointed the director of Cambridge University and chairman of Cavendish Laboratory. This was a memorable day for Rutherford as he had succeeded his guide J J Thomson. Thomson’s another student James Chadwick discovered neutron in 1932, though Rutherford had predicted the existence of such a particle long before. The ‘Father of Proton’, researcher of radioactivity, Rutherford died in 1937. He published about 80 research papers, winning respect, honour and medals, aptly to be called Lord Ernest Rutherford of Nelson.

John Logie Baird

The inventor of the television, John Logie Baird was born on August 13, 1888, at a hamlet Helensburgh, Dunbarton, near Glasgow, Scotland. Son of a Scottish engineer, he became the first man to televise pictures of objects in motion. The Youngest in the family, John was of weak constitution and often remained ill, especially afflicted with cold. This affected his study. He did not have any particular interest in reading. His only interest was photography. He was a member of his school photography club. Boys took photographs all by themselves. The club held a monthly competition wherein the best photograph among those clicked by the students was awarded a prize.

John had another interest too. He conducted experiments using electric wires. He had a particular interest in telephone. He had even linked a telephone line from his home to his friend’s house at some distance and both would talk for hours on this indigenous phone line. On one particular stormy night the wires broke off, and got tangled and coiled around the neck of passerby. Luckily, the man was saved, but John got the scolding of his life and thus ended this saga. As he grew up, his electrical experiments increased. Once, he thought of creating diamonds. He thought out a formula and collected the required material, some of it explosive in nature. But the volatile explosive material suddenly caught fire resulting in a blast. Though he was saved, he vowed never to do such dangerous experiments.

With a view to be an engineer, Baird took up a job at an electricity company. He realized that he had to earn his bread. But he was not much comfortable at his work. One day he was so severely struck by bad cold that he was confined to his bed. To keep himself warm, he wrapped papers on his feet. It worked. This triggered him of an idea to make socks. He brought necessary things the next morning, dyed the cotton yarn in various colours and made colourful socks. He went to a shopkeeper and showed his creation. The shopkeeper bought all the socks and asked him to supply more. Soon, Glasgow dwellers were using this innovative creation of Baird. Later, he employed people for mass production of socks.

He was once again down with severe cold and illness. The doctor advised him to stay at a place with warmer climate. He decided to go to West Indies. He was happy with the prospect of the extended market for socks. But the shopkeepers in West Indies did not show any interest in his socks. He was unable to sell even a single pair of socks. His ever creative mind thought of something else. West Indies had many orchards of lemon, orange and sugar cane. He thought of pickle factory and soon discovered to his horror that the sugar and the sweet aroma of pickles attracted some poisonous insects in the area. They even bit Baird. His health further deteriorated and he returned to London.

The cold climate of London did not suit him as it was very cold there and the doctor advised him to move near the seashore. This worked. On a pleasant evening, while he was taking a stroll on the beach, he heard a song on radio playing at a nearby hotel. Suddenly it struck him: sound could travel far through waves. He wondered if it was possible to send visuals the same way. He started working on this concept. He collected the required material: wire, and empty trunk, batteries, empty cookie tins, bicycle headlight, candle, etc. He worked continuously for days experimenting on the contraption. Finally, he could produce a blurred picture on a screen in his room. Now, he worked hard to obtain a clearer picture. When his landlord came to know about his experiments, he threw him out. But he was undeterred. He returned to London and worked even more enthusiastically. After many days, he succeeded in producing clear images on the screen. Coming to know the experiment and its results, people started dropping at his residence, taking keen interest in his work. Once, Baird made a boy stand in one room and showed his image on a screen in another room. He could even show the movements of the boy clearly on the screen. He was extremely delighted with his success.

He invited scientists and journalists for a demonstration. They appreciated his work and congratulation him for his invaluable invention. Soon, the world knew about Baird and his invention. Initially, the pictures appeared blurred, but soon they became clear. He even succeeded in relaying colored pictures. Now, he started relaying opera and theatre on his television. He even started work on developing a television set. Despite employing many people he was unable to meet the public demand. In fact, he had envisioned a television station on the lines of a radio station. But commencement of World War II marred his plans. Besides, his relay station was also bombarded and destroyed. Meanwhile, he progressed towards the broadcast of colour pictures.

Once again he was struck by a bout of severe cold. This time it was life threatening. He left the experiments midway and returned home. On June 14, 1946, at Bexhill – on-Sea, Sussex, England, this after presenting the world with the wonderful gift – television, the 58 year old John Logie Baird bid adieu.