My Science School

Have you ever wondered where precious metals like gold come from? Or how they became embedded in the deep crevices of our planet?

A gift from the stars

Gold is extraterrestrial. This means instead of arising from our planet's rocky terrain, this metal was actually created in space. Its presence on the Earth is a consequence of the cataclysmic explosions called supernovae. This powerful and luminous explosion occurs towards the end of a star's life.

Supernova

Matter is made up of atoms. These atoms consist of subatomic particles like protons (positively charged particles), electrons (which have a negative charge) and neutrons (neutral particles that form the centre of an atom). The region of an atom that accommodates neutrons is called a nucleus.

When two or more atoms' nuclei (plural of nucleus) merge to form a heavier atom, a large amount of energy is dissipated into the surrounding. This process is known as nuclear fusion.

Stars are mostly made up of hydrogen, which is the simplest and the lightest of all the elements. With time, the enormous gravitational pressure of so much material compresses and triggers nuclear fusion in a star's core.

The energy released due to this fusion is the reason why stars shine. Over millions of years, this fusion transforms hydrogen into heavier elements like helium, carbon, and oxygen. These heavier elements burn faster and faster to make iron and nickel.

Towards the last phase of a stars life, this fusion is unable to release enough energy, and the pressure from the core forces the outer layers of the heavenly body to collapse into the centre. This sudden injection of energy results in the explosion of the star or a supernova.

The pressure of this explosion is so high that it forces various subatomic particles to fuse and form neutrons. These neutrons are then captured and combined by the residual heavy metals from the star. This leads to the formation of heavier elements like gold, silver, lead and even uranium. The formation of heavy metals in a supernova takes place within seconds.

The remnants of supernova

The expanding shock wave from the explosion propels the remnants through space. The supernova debris enriches the space clouds and condenses to form new planets and stars.

Researchers have found that Earth's reserve of gold is most likely a direct consequence of this phenomenon. This would mean that the cosmic cloud that condensed to form our planet had gold particles, which were then kneaded into the planet's crust due to the movement of the tectonic plates and other Geo-thermal activities.

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The popping sensation in the ears is caused by the effect of the changes in pressure and altitude. The most important part of the ear is the eardrum, a thin membrane separating the outer ear from the middle ear. Equal air pressure is maintained on both sides of the membrane by the Eustachian tube, a tube which connects the ear and the throat. Sudden changes in the air pressure like when going up or down in an aeroplane stretches the eardrum, causing discomfort. The Eustachian tube tries to normalise the pressure by forcing more air into the ear internally through. yawning or swallowing. This adjustment creates the popping sound which indicates that the air pressure is back to normal in the ear. Ears may pop even when you travel in a high speed elevator of a tall building or go scuba diving.

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When you open the fridge, warm air from outside rushes in. When you close the door, the warm air cools and contracts, creating a temporary vacuum that keeps the door stuck to the fridge. The vacuum effect lasts only seconds so you can soon open the door comfortably again.

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Air is compressible, water is not. When the tyre hits a bump or drops into a depression on the road, the impact pushes the air in the tyre into a smaller space. Thus the shock of the impact is absorbed by the cushion of air in the tyre, and is not passed on to the body of the car and consequently to the passengers.

Water cannot get compressed in this way. If a water-filled tyre were to hit a bump on the road, the water would retain its rigidity. As a result, the shock of impact would be passed on to the body of the car, jolting the passengers.

Secondly, water-filled tyres would increase the weight of the wheels and the vehicle would have to overcome greater rolling resistance. This would increase the load on the engine.

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Try to balance a one-rupee coin on its edge. It'll topple over. However, if you flick it with your finger and make it spin it'll stand on its edge while it is spinning. Why?

While the coin is spinning its centre of gravity runs straight down through it from edge to edge, keeping the spinning coin in place and balanced However, when it slows down, its centre of gravity falls outside its base and it topples over. You are able to ride your cycle because when the wheels are moving they can balance on edge and keep the cycle upright. When the wheels stop moving the cycle topples over.

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If you attach a stone to a piece of string and whirl it around, you will feel the string tighten and the stone being pulled away. If the string is not strong, it will break and the stone will be hurled away in a straight line. This is the power of centrifugal force, the force exerted on a body in circular motion

When a cyclist takes a turn in a curved motion he is subjected to centrifugal force which pushes him to the edge of the curve. To maintain his balance he has to lean inwards while turning.

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A candle is burning. You blow hard and the flame gets extinguished. Why? Is it because of the carbon dioxide we exhale when we blow out? That can't be the reason because a gust of wind can also blow out the candle and the wind carries a lot of oxygen along with it.

The reason why the candle goes out is that when you blow hard you remove the warm air around the flame. Cooler air takes its place. This lowers the temperature of the burning wax to below its ignition point. The wax stops burning and the candle goes out.

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A black hole is an astronomical object with a gravitational pull so strong that nothing, not even light, can escape it. A black hole's “surface,” called its event horizon, defines the boundary where the velocity needed to escape exceeds the speed of light, which is the speed limit of the cosmos.

In astrophysics, an event horizon is a boundary beyond which events cannot affect an observer. Wolfgang Rindler coined the term in the 1950s. In 1784, John Michell proposed that gravity can be strong enough in the vicinity of massive compact objects that even light cannot escape. At that time, the Newtonian theory of gravitation and the so-called corpuscular theory of light were dominant. In these theories, if the escape velocity of the gravitational influence of a massive object exceeds the speed of light, then light originating inside or from it can escape temporarily but will return. In 1958, David Finkelstein used general relativity to introduce a stricter definition of a local black hole event horizon as a boundary beyond which events of any kind cannot affect an outside observer, leading to information and firewall paradoxes, encouraging the re-examination of the concept of local event horizons and the notion of black holes. Several theories were subsequently developed, some with and some without event horizons. One of the leading developers of theories to describe black holes, Stephen Hawking, suggested that an apparent horizon should be used instead of an event horizon, saying, "gravitational collapse produces apparent horizons but no event horizons." He eventually concluded that "the absence of event horizons means that there are no black holes – in the sense of regimes from which light can't escape to infinity."

Any object approaching the horizon from the observer's side appears to slow down, never quite crossing the horizon. Due to gravitational redshift, its image reddens over time as the object moves away from the observer.

Credit : Wikipedia 

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A gravitational singularity, spacetime singularity or simply singularity is a condition in which gravity is so intense that spacetime itself breaks down catastrophically. As such, a singularity is by definition no longer part of the regular spacetime and cannot be determined by "where" or "when". Trying to find a complete and precise definition of singularities in the theory of general relativity, the current best theory of gravity, remains a difficult problem. A singularity in general relativity can be defined by the scalar invariant curvature becoming infinite or, better, by a geodesic being incomplete.

Gravitational singularities are mainly considered in the context of general relativity, where density apparently becomes infinite at the center of a black hole, and within astrophysics and cosmology as the earliest state of the universe during the Big Bang/White Hole. Physicists are undecided whether the prediction of singularities means that they actually exist (or existed at the start of the Big Bang), or that current knowledge is insufficient to describe what happens at such extreme densities.

General relativity predicts that any object collapsing beyond a certain point (for stars this is the Schwarzschild radius) would form a black hole, inside which a singularity (covered by an event horizon) would be formed. The Penrose–Hawking singularity theorems define a singularity to have geodesics that cannot be extended in a smooth manner. The termination of such a geodesic is considered to be the singularity.

The initial state of the universe, at the beginning of the Big Bang, is also predicted by modern theories to have been a singularity. In this case, the universe did not collapse into a black hole, because currently-known calculations and density limits for gravitational collapse are usually based upon objects of relatively constant size, such as stars, and do not necessarily apply in the same way to rapidly expanding space such as the Big Bang. Neither general relativity nor quantum mechanics can currently describe the earliest moments of the Big Bang, but in general, quantum mechanics does not permit particles to inhabit a space smaller than their wavelengths.

Credit : Wikipedia 

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The Four Fundamental Forces of Nature are Gravitational force, Weak Nuclear force, Electromagnetic force and Strong Nuclear force. The Four Fundamental Forces of Nature are Gravitational force, Weak Nuclear force, Electromagnetic force and Strong Nuclear force.

Gravitational Force

The gravitational force is weak but very long-ranged. Furthermore, it is always attractive. It acts between any two pieces of matter in the Universe since mass is its source.

Weak Nuclear Force

The weak force is responsible for radioactive decay and neutrino interactions. It has a very short range and. As its name indicates, it is very weak. The weak force causes Beta-decay ie. the conversion of a neutron into a proton, an electron and an antineutrino.

Electromagnetic Force

The electromagnetic force causes electric and magnetic effects such as the repulsion between like electrical charges or the interaction of bar magnets. It is long-ranged but much weaker than the strong force. It can be attractive or repulsive and acts only between pieces of matter carrying an electrical charge. Electricity, magnetism, and light are all produced by this force.

Strong Nuclear Force

The strong interaction is very strong but very short-ranged. It is responsible for holding the nuclei of atoms together. It is basically attractive but can be effectively repulsive in some circumstances. The strong force is ‘carried’ by particles called gluons; that is, when two particles interact through the strong force, they do so by exchanging gluons. Thus, the quarks inside of the protons and neutrons are bound together by the exchange of the strong nuclear force.

Note:  While they are close together the quarks experience little force, but as they separate the force between them grows rapidly, pulling them back together. To separate two quarks completely would require far more energy than any possible particle accelerator could provide.

Credit : Clearias

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When the Moon passes between Sun and Earth, the lunar shadow is seen as a solar eclipse on Earth. When Earth passes directly between Sun and Moon, its shadow creates a lunar eclipse. Lunar eclipses can happen only when the Moon is opposite the Sun in the sky, a monthly occurrence we know as a full Moon. Lunar eclipses can happen only when the Moon is opposite the Sun in the sky, a monthly occurrence we know as a full Moon. But lunar eclipses do not occur every month because the Moon's orbit is tilted five degrees from Earth's orbit around the Sun, so most of the time the Moon passes above or below the shadow. Without the tilt, lunar eclipses would occur every month.

Lunar and solar eclipses occur with about equal frequency. Lunar eclipses are more widely visible because Earth casts a much larger shadow on the Moon during a lunar eclipse than the Moon casts on Earth during a solar eclipse. As a result, you are more likely to see a lunar eclipse than a solar eclipse.

Credit : Stardate 

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A comet has two tails. One is a dust tail pushed by light from the sun. Wired Science blogger Rhett Allain uses physics to explain how light can push on matter.

There are two tails because there are two ways the comet can interact with the sun. Everyone thinks about light coming from the sun. However, there is also the solar wind. The solar wind is really just charged particles (like electrons and protons) that escape from the sun due to their high velocities. These charged particles then interact with the ionized gas produced from the comet.

The other tail is due to an interaction with the dust produced by the comet and the light from the sun. Really, it is this interaction that I want to talk about.

Credit : Wired.com

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The nucleus is the solid core of a comet consisting of frozen molecules including water, carbon monoxide, carbon dioxide, methane and ammonia as well as other inorganic and organic molecules — dust. According to ESA the nucleus of a comet is usually around 10 kilometers across or less.

Comets are separated into three distinct parts called the tail, nucleus and the coma which ensures its workability. Comets work in the sense that they tend to be more explicit when they come closer to the source of illumination, the Sun. The tail of a comet is made up of three other parts, the ion tail, the hydrogen envelope, and the dust tail. All these are also vital for the movement of the comet both to and from the sun as indicated below.

The nucleus of a comet is made up of ice, gas, dust, and rocks. It is found right at the center of the head of a comet. The nucleus of a comet is often frozen. The part which is occupied by the gas in the comet’s nucleus is made up of carbon dioxide, the carbon monoxide, ammonia, and methane.

The comet’s area which is made up of the nucleus encompasses between 0.6 to around 6 miles. At times, it is even more than this distance. The nucleus, following this combination of materials, carries the most mass of the comet. The nucleus of a comet is also regarded as one of the darkest objects ever witnessed in the space.

Credit : Earth eclipse

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Coma. As a comet gets closer to the sun, the ice on the surface of the nucleus begins turning into gas, forming a cloud around the comet known as the coma. According to science website howstuffworks.com the coma is often 1,000 times larger than the nucleus. Outside the coma is a layer of hydrogen gas called a hydrogen halo which extends up to 1010 meters in diameter. The solar wind then blows these gases and dust particles away from the direction of the Sun causing two tails to form. These tails always point away from the Sun as the comet travels around it. One tail is called the ion tail and is made up of gases which have been broken apart into charged molecules and ions by the radiation from the Sun. Since the most common ion, CO+ scatters the blue light better than red light, to observers, this ion tail often appears blue.

Credit : lco global 

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What you will need

A wad of old newspaper, large plastic tub, glass tumbler, water.

What you do:

• Fill the tub with water.
• Scrunch up the newspaper and stuff it in the bottom of the glass tumbler. upside down to make sure that the paper does not slip out.
• Holding the tumbler upside down, plunge it straight down to the bottom of the tub.
• Pull out the glass from the water.
• Do not tip the glass to the side at any time during the experiment.

What do you observe?

 When you take out the newspaper, you will find that it is absolutely dry!

Why does this happen?

 Air occupies space. When you submerge the tumbler, the air inside the glass cannot escape. It acts as a block, preventing the water from entering the glass. Hence the newspaper does not get wet.

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