My Science School

              The Higgs particle is one of the 17 particles in the Standard Model, which is the model of physics describing all known basic particles. Bosons are thought to be particles which are responsible for all physical forces. Higgs particle is a boson and so are photon, W and Z bosons and gluon.

             Higgs Boson cannot be easily detected. It does not last long because it is massive when compared to other particles. There are usually no Higgs Bosons around because it takes so much energy to make one. It was mainly for this reason that the Large Hadron Collider at CERN was built.

             The existence of Higgs Boson was first suggested by Peter Higgs in the 1960s. Scientists at CERN tentatively confirmed on 14 March 2013 that they had found a Higgs particle.

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            The term LASER originated as an acronym for Light Amplification by Stimulated Emission of Radiation.

            Absorbing energy excites atoms and molecules. When they are struck by radiation of a suitable frequency, they release their energy as a wave exactly in step with that radiation. Albert Einstein had predicted this stimulated emission in 1917.

            In a laser, new radiation strikes other excited atoms, which emit light and lead to a chain reaction. This produces high-intensity radiation with all the waves in step with each other.

            Laser light is considered pure because it consists of waves of a single frequency, all in step. Laser can be used in instances when light made of jumbled waves of different frequencies is not enough. It can be extremely intense, allowing us to cut metal using it, and narrower than an ordinary beam of light. Lasers are used to make accurate measurements. Their narrow beam is used in surveying to bounce off distant reflectors and give pinpoint positioning. The content in a CD is read by tiny low-powered infrared lasers. Holograms and light shows also make use of lasers.

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            Nuclear fission is the process by which an atom splits into lighter atoms, releasing considerable energy. Its discovery had a substantial effect on energy delivery, geopolitics and advancements in science and medicine.

            Bombarding uranium with neutrons causes nuclei of its atoms to split and form lighter elements. German chemists Otto Hahn and Fritz Strassmann discovered this in 1938. But the process was explained and named ‘nuclear fission’ by Austrian physicists, Lise Meitner and her nephew Otto Frisch. On realising its potential in making bombs, they alerted other physicists who in turn informed the US president. Later, nuclear fission was used in making the atom bombs dropped on Hiroshima and Nagasaki.

            Otto Hahn was awarded the Nobel Prize in Chemistry in 1944 for this discovery. Hahn, Meitner and Strassman stood firm against the use of nuclear technologies for military purposes. And they refused to be involved in the development of nuclear weapons though their discovery had made it possible.

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            Normally, it takes an effort to make fluids flow. However, this behaviour changes at really low temperatures. In 1937, Russian physicist Pyotr Kapitsa discovered that below -271 degrees Celsius liquid helium loses its resistance to flow. It even exhibits quirky habits such as turning into a thin film and climbing up the walls of its container.

            Kapitsa published his findings 1938. Canadian physicist, John Allen, who had discovered it independently, also published his findings the same year.

            Superfluidity in helium occurs when helium-3 and helium-4, the two isotopes of helium, are liquefied by cooling to cryogenic temperatures (-150°C to -273 °C). Superfluidity occurs at far higher temperatures in liquid helium-4 than it does in helium-3.

            Superfluidity has many applications in astrophysics. Superfluid helium at -271.4 °C was used in a special device in 1983 and many other devices for astronomical observations with infrared sensors.

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            Wolfgang Pauli proposed the existence of a neutral, light-weight particle present in the nucleus of an atom. This suggestion helped safeguard the fundamental law of the conservation of energy by explaining the apparent loss of energy during decay of certain atomic nuclei.

            Scientists elaborated Pauli’s idea in the 1930s. The neutral particle discovered by James Chadwick in 1932 was named neutron. However, neutron was too heavy to be what Pauli predicted.

            While developing a theory of weakly interacting particles, Enrico Fermi introduced the name ‘neutrino’ which means ‘little neutral one’ for Pauli’s particle.

            Neutrino is electrically neutral and has a rest mass so negligibly small, it was considered to be zero. Neutrino is smaller than other known elementary particles. As a neutrino abstains from strong interactions, it can pass through normal matter without obstruction and evade detection.

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            The widely accepted theory about the origin of our universe centres on the event now referred to as the ‘Big Bang.’ The basis of this theory is the observation that galaxies are moving away at great speed from one another. It was as if they were forced into movement by an ancient explosive force.

            Georges Lemaitre, a Belgian priest first came up with the Big Bang Theory in the 1920s. He suggested that a single primordial atom exploded to create the universe. Hubble’s observations substantiated Lemaitre’s theory. In addition to this, cosmic microwave radiations discovered by Arno Penzias and Robert Wilson in the 1960s were seen as reverberations of the Big Bang.

            Russian physicist George Gamow revived Lemaitre’s ideas in 1948 in order to explain the formation of chemical elements. British astronomer Fred Hoyle is credited for coining the expression ‘Big Bang,’ but he had actually used the term critically to reject this theory. Today, however, the Big Bang is the accepted explanation for the beginning of time.

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            In 1929, American astronomer Edwin Hubble published one of the astounding discoveries of the twentieth century. Through observations of far off galaxies, Hubble found that the universe is expanding and the galaxies are moving away from each other. Their speeds kept increasing, the farther they were from each other. This theory is known as Hubble’s Law.

            Hubble’s Law is regarded as the first observational foundation for the expansion of the universe. However, the idea of universe expanding at a calculable rate was not introduced by Hubble. Alexander Friedmann derived this from general relativity equations in 1922 which was published as the ‘Friedmann equations.’ After Hubble’s discovery, Einstein called his own assumptions about a static universe his ‘biggest mistake.’

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            According to the definition in quantum mechanics, a particle is not just a particle, but also a wave. As a result, it is impossible to know the momentum, which is a product of the mass and velocity, and position of a particle, simultaneously. This is because momentum comes from a wave that is spread out while position comes from a concentrated wave. And these two do not come together.

            This was proposed by the German physicist Werner Heisenberg as the ‘Uncertainty Principle’ in 1927. It is to be noted that the Uncertainty Principle is not apparent on the macroscopic scale of day-to-day life. Scientists usually devise easily understood physical situations as examples to demonstrate the application of the Uncertainty Principle.

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            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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            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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            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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            A black hole is a great amount of matter packed into a very small area. For example, the image of a star, ten times the size of the sun squeezed into a sphere aptly describes it. The result is a gravitational field so strong that, even light can’t escape. Most black holes are formed of the remnants of a large star that dies in a supernova explosion.

            The idea of an object in space, dense enough to prevent even light from escaping is centuries old. Einstein first predicted black holes in 1915 with his General Theory of Relativity. Karl Schwarzschild used Einstein’s General Theory of Relativity to find out what happens near a massive star that has collapsed to a single point. He found that they emit no light, but can be detected by the effect of their gravity on nearby stars.

            Astronomer John Wheeler coined the term black hole in 1967. Cygnus X-1, the first object considered to be a black hole was discovered in 1964.

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            The theory of relativity includes two interrelated theories by Albert Einstein: Special Theory of Relativity and General Theory of Relativity.

            Simply put, the Special Theory says that the mass of an object depends on its speed. If a force acts on an object, it accelerates. But as it speeds up, more energy goes into increasing its mass and less into increasing its speed.

            This prevents it from reaching the speed of light. One consequence is the equation E =square which says that mass and energy are interchangeable.

            Though revolutionary, the Special Theory of Relativity was incomplete by itself as gravity was not accounted for.

            Einstein remedied this in 1915 with his General Theory of Relativity. He replaced Newton’s space and time with a unified space-time. According to this, gravity was a property of space, not a force between bodies. The final form of general relativity was published in 1916.

            Einstein’s theory revolutionized theoretical physics and astronomy.

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            Electromagnetic radiations called X-rays were discovered by Wilhelm Roentgen in 1895 while investigating cathode rays. Cathode rays are electrical discharges inside a tube containing very little air.

          Roentgen observed certain crystals lying near the tube that glowed while the tube was working. This was puzzling because the tube was shielded to prevent light from escaping it.

            Roentgen deduced that cathode rays hitting the glass of the tube were producing some other rays which made the crystals glow. Further experiments showed that these rays could also pass through solid objects and affect photographic plates. Roentgen used this property to make the first X-ray picture. He was initially reluctant to reveal his discovery to the public, afraid that other scientists may not believe him. Proving his worries baseless, the public wholeheartedly accepted X-rays.

            Roentgen discovered their medical use while making a picture of his wife’s hand on a photographic plate using X-rays. The photograph of his wife’s hand was the first photograph of a human body part using X-rays!

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