Category Great Scientific Discoveries

How did Newton’s experiments prove the components of white light?

Newton’s discoveries revolutionized our understanding of the most common aspects of nature such as light. Prisms were seen as trivial toys used for fun in laboratories until Newton came across them. He conducted a series of experiments with sunlight and prisms after getting a prism at a fair in 1664.

Newton made the astonishing discovery that clear white light was composed of seven visible colours. The visible spectrum, the seven colours of the rainbow, was scientifically established by Newton. This discovery opened new vistas in optics, physics, chemistry, and the study of the colours in nature.

One bright sunny day, Newton darkened his room and made a hole in his window shutter, allowing just one beam of sunlight to enter the room. He then took a glass prism and placed it in the sunbeam. The result was a spectacular multi-coloured band of light just like a rainbow.

Newton believed that all the colours he saw were in the sunlight shining into his room. He thought he then should be able to combine the colours of the spectrum and make the light white again. To test this, he placed another prism upside-down in front of the first prism. He was right. The band of colours combined again into white sunlight. Newton was the first to prove that white light is made up of all the colours that we can see.

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Why is Isaac Newton considered to be one among the greatest mathematicians?

We may remember Newton mostly in association with the theory of gravity and the story of the apple tree. But he was also a great mathematician on par with legendary figures like Archimedes and Gauss. Newton’s contributions paved the path for numerous mathematical developments in the succeeding years.

Until Newton, algebraic problems where the answer was not a whole number posed a problem for mathematicians. The formula published by Newton in 1676 called ‘binomial theorem’ effectively resolved this issue. It has been said that through Newton’s works, there was remarkable advancement in every branch of mathematics at the time.

Newton (along with mathematician Gottfried Wilhelm von Leibniz) is credited with developing the essential theories of calculus. He developed the theory of calculus upon the earlier works by British mathematicians John Wallis and Isaac Barrow, and prominent mathematicians Rene Descartes, Pierre de Fermat, Bonaventura Cavalieri, Johann van Waveren Hudde and Gilles Personne de Roberval.

While Greek geometry was static, calculus allowed mathematicians and engineers to make sense of the dynamic world around them. They could now make sense of motion such as the orbits of planets and the flow of fluids.

Many modern historians believe calculus was developed independently by Newton and Leibniz, using different mathematical notations. Leibniz was however, the first to publish his results.

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Why the year Newton spent in his home during the Great Plague is called his ‘year of wonders’?

With the outbreak of the bubonic plague, Cambridge University closed its doors in 1665. As a result, Newton was forced to return home to Woolsthorpe Manor where he ended up staying with his mother for over a year. In the peaceful countryside, he concentrated on the scientific problems about which he had wondered during his post graduate years.

Some of his greatest discoveries such as the laws of gravity, laws of motion, and the components of white light had their origin during this time.

It is said that Newton was sitting in the orchard when he saw an apple falling from a tree. Contrary to popular versions of this event, there is no evidence to suggest that the apple had fallen on his head. Pondering upon what he saw, Newton wondered why apples fall straight to the ground rather than going upwards or sideways. Following this line of thought, he finally formulated the law of universal gravitation.

This was the account of his discovery given by Newton himself to his acquaintances including the French philosopher Voltaire; his assistant at the Royal Mint, John Conduitt who was the husband of his niece Catherine Barton; his friend William Stewkeley; and Christopher Dawson who was a student at Cambridge. The note on Newton’s life collected by John Conduitt in 1726 contains the first written account.

The year he spent in Woolsthorpe later came to be called his annus mirabilis (year of wonders). Newton returned to Cambridge in 1667.

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When were cosmic rays discovered?

            Cosmic rays were discovered in 1912 by Victor Hess. These are fragments of atoms that reach Earth from beyond the solar system. They travel nearly at the speed of light and are said to cause electronic problems in satellites and other machinery.

            Though a century has passed since their discovery, cosmic rays still remain an enigma. We are still unsure about the source of cosmic rays. Most scientists associate their origins to supernovas (explosions of stars). However, they appear uniform when you look across the entire sky through observatories.

            The year 2017 saw major advancements in cosmic ray science. Pierre Auger Observatory which is spread over 3,000 square kilometres in western Argentina studied the arrival trajectories of 30,000 cosmic particles. Depending on where they looked, the observatory found differences in the frequency at which these cosmic rays arrived.

            The exact origins of cosmic rays are still hazy, but scientists agree that the first step is knowing where they ought to look.

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Why is it said that the quantum theory changed physics forever?

            One of the troubles encountered by physicists in the 1900s was that the colour of light from red-hot objects differed from their expectations. Max Planck, a German physicist, found a way to predict the colour accurately. He assumed that energy radiated only as multiples of a fixed amount called quantum. This also clarified why the energy of electrons ejected from metals by light depended on the colour of the light rather than brightness.

            In the next three decades, Erwin Schrodinger, Werner Heisenberg and others utilized the quantum theory to develop a new world view in which matter and energy could be both waves and particles.

            These developments transformed physics. The theoretical basis of modern physics is built on two theories: the theory of relativity and quantum theory. The first one is relevant when high speeds are involved and quantum theory is required when quantities on the scale of atoms, molecules, etc. are involved.

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Who discovered superconductors?

            Superconductors are materials that conduct electricity without resistance. As a result, they can conduct electricity indefinitely without losing energy unlike common conductors like copper and steel.

            In 1911, Dutch physicist Heike Kamerlingh Onnes of Leiden University first observed superconductivity in mercury. When he cooled it to the temperature of liquid helium, which is 4 degrees Kelvin its resistance suddenly disappeared. The Kelvin scale represents an absolute scale of temperature.

            Heike Onnes also discovered that a superconducting material can be returned to normal, non-superconducting state, in two ways. This can be done either by passing a sufficiently large current through it or by applying a sufficiently strong magnetic field. In 1913, Onnes was awarded the Nobel Prize in physics for his research in this area.

            The discovery of superconductors has made drastic improvements in the medical field. With the advent of MRI machines, exploratory surgeries are no longer as necessary as it once was.

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