Category: Science & Nature

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Card Shuffling

Posted on by Jinavie

Take a standard deck of playing cards. Shuffle it thoroughly and set it on the table. Consider this: what is the probability that the order those 52 cards are in is the same as the order of a deck shuffled by someone else? The answer can be found using a simple maths equation: 52!

! denotes a factorial, where you multiply the number to every other positive integer smaller than it. For example, 5! = 5 x 4 x 3 x 2 x 1 = 120. Due to its nature, factorials grow rapidly – even faster than exponentials. For example, 10! is 3.6 million and 15! is 1.3 quadrillion. By 52!, the number grows to:

80,658,175,170,943,878,571,660,636,856,403,766,975,289,505,440,883,277,824,000,000,000,000.

This number is so big that if every star in our galaxy had a trillion planets, each with a trillion people living on it, all shuffling a trillion deck of cards at the rate of 1000 shuffles per second, since the beginning of time, only now would someone have a deck that is in the exact order as your deck.

Ergo, you can say with absolute, mathematical certainty, that the deck you have shuffled is in an order never created by any human being in the history of the world.

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Posted in Science & Nature

Discomfort Index

Posted on by Jinavie

Hot and humid weather is quite possibly the worst weather, as most people will feel sticky and uncomfortable, to the point that it will affect their mood and ability to think. This combination is so terrible that weather forecasts often mention a discomfort index (or temperature-humidity index) to highlight how hot and humid the day will be. Discomfort index is calculated as:

DI = 40.6 + 0.72 (dry-bulb temperature + wet-bulb temperature ).

Here, dry bulb temperature is the “ambient temperature” (not considering humidity), while wet bulb temperature accounts for humidity by looking at how low the temperature can get by evaporating water.

Evaporation absorbs heat but can only happen if the air is not saturated with humidity. Therefore, the more humid it is, the more “discomfort” we feel as we cannot sweat off the heat building up inside our bodies.

When the DI is at 70, about 10% of people experience discomfort. At 75, 50% feel discomfort and at 80, most people will feel extremely uncomfortable. A DI of above 85 is virtually intolerable and anything above this, serious conditions such as heat exhaustion and heat stroke can occur.

As our core body temperature rises and we cannot cool down by sweating, we experience thermal stress. Under thermal stress, our concentration and task performance begins to suffer – a phenomenon people will describe as their brain feeling as if it is melting. This is a well-established phenomenon that has significantly affected how architects design offices and homes to improve air flow and temperature control to create an environment with the least thermal stress possible – for both efficiency and comfort.

Posted in Science & Nature

Fusion

Posted on by Jinavie

One of the greatest challenges for modern science is unlocking the secret of nuclear fusion. Nuclear fusion presents the opportunity for humanity to obtain an extremely efficient yet surprisingly clean source of energy. Einstein’s famous equation – E=mc² – shows the relationship between energy and mass. It turns out that all matter is essentially energy, meaning that by breaking apart the matter to its basic constituents, you can unleash energy.

When two hydrogen atoms are collided together at extremely high speeds, the two protons join with enough energy to form deuterium, while releasing energy. As more hydrogens are collided, helium is formed while releasing more energy and also hydrogen, which can fuse with other hydrogen to start more reactions. This is a chain reaction. Once the chain reaction is established, the fusion reaction will keep producing immense amounts of energy until it uses up all the hydrogen available.

However, there are two main problems we are still trying to solve when it comes to unlocking fusion. The first is generating enough energy to kickstart the chain reaction in the first place, which is called ignition. The second is containing this immense energy, as the intense heat produced would melt any material we can produce to contain it.

This brief overview of nuclear fusion also offers a lesson in life. Most of the good things in life are not single events, but self-sustaining processes. Things like good habits, happiness and human relationships. To form a good habit, you must invest incredible amounts of time, resources and willpower. To start a relationship, you need to make an effort to show the other person how much they mean to you. To be happy, you need to completely change the way you perceive the world.

The best things in life do not happen by accident, but because you made an effort to ignite the chain reactions. Of course, you will constantly need to maintain those reactions so they don’t explode on you, but at the end of the day, starting is really half the battle.

(Couldn’t come up with an appropriate picture for this article……..so here’s a gif of Groot dancing)

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Zero Gravity

Posted on by Jinavie

With the development of technology, we are now at a point in history where there is an abundance of video footages taken in space. Thanks to this, the general population can visualise the strange phenomenon that is the lack of gravity in space. We are able to see videos of objects and astronauts gently floating and even strange phenomena such as tears simply pooling around a person’s eyes rather than streaming down the face. Most of these scenes are from places such as the International Space Station which is in orbit around the Earth, as there has been no expeditions leaving Earth’s orbit since the last moon landing in 1972.

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However, the common misconception is that objects in space stations are in zero gravity conditions. Objects in orbit are still under the influence of Earth’s gravity, which is why they do not fling out into the depths of space. So why do astronauts in space stations look like they are not under the influence of gravity? The reason is that an object in orbit is travelling incredibly fast.

The International Space Station is about 420km above the surface of the Earth. Here, it experiences about 90% of Earth’s surface gravity, meaning that theoretically, it should fall straight back. However, the ISS is travelling at 8km/s (27600km/h) sideways at the same time – the orbital speed. Because of this, the ISS is falling back to Earth at the same rate as it is travelling tangentially away from Earth. This makes it travel at a blistering speed in a circle around the Earth.

Not only is the ISS free-falling around the Earth, but so is its contents. Therefore, the astronauts inside look like they are in zero gravity, but are in fact simply in free-fall, much like a skydiver. In this state, they experience no “weight” as the g-force becomes zero and the astronauts accelerate at the same rate as the ISS. Ergo, the astronauts are “weightless”, not in “zero gravity”. This condition can be simulated on Earth in the so-called “Vomit Comet” – an airplane designed to fly up and down along a certain path, to produce a weightless, free-fall when it falls.

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Turing Test

Posted on by Jinavie

Alan Turing was a brilliant British mathematician who was pivotal in cracking the German Enigma cipher using a complex computing machine. He was highly influential in the founding of computing science. One of his greatest areas of interest was artificial intelligence. Like other computer scientists of the time, Turing predicted that machine intelligence was possible in the future with rapid development of computers. On this topic, he proposed the following question: at what point is a machine truly “intelligent”?

Intelligence is too complicated to define neatly in a single line. Therefore, here is a simpler question: can a machine do what we can do? For this, he proposed a thought experiment based on a party game known as the imitation game. In the imitation game, a man and a woman go into separate rooms. Guests then try to tell who is a man and who is a woman by writing a series of questions, slipping it under the door, then receiving a typewritten answer. If the guests cannot tell the two apart, the two win the game.

Turing modified this game into what is now known as the Turing test. He proposed replacing one person with a machine. A person and a computer are placed in separate rooms and are asked the same question by a judge. They then give a typed response. If the judge cannot confidently tell who is human and who is not, then the machine passes the Turing test.

Of course, the Turing test was not designed as a formal assessment and is merely a thought experiment. It has plenty of weaknesses, such as the fact that it only tests whether the machine is acting “like a human” rather than “intelligently”. For example, some computers have passed the Turing test by intentionally making typos to mimic human behaviour. Some have argued that machines that pass the Turing test do not truly exhibit intelligence, as it is impossible to tell if they fully understand the language or whether they are just running algorithms on symbols that the machine does not understand.

Regardless, the Turing test opens the door on the exciting yet frightening world of artificial intelligence and what the future holds for humanity.

Turing Test

(Image source: http://xkcd.com/329/)

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Dust Explosion

Posted on by Jinavie

When we hear explosives, we commonly think of chemicals such as nitroglycerin or gunpowder. But an explosion is essentially just a rapid release of energy and expansion of gases due to combustion. This means that if something is combustible – that is, it can burn – it has the ability to explode. However, certain conditions have to be met so that the combustion can be sudden and rapid.

Because of this principle, it is possible to explode dust or other powdered substances. If the dust is combustible (such as flour or coal), suspended in the air at enough concentration in a confined space, with sufficient oxygen and an ignition source, a dust explosion can occur. For example, coal dust explosions are a common threat to miners and there have been countless incidents where mills and factories have exploded with great fury due to a dust cloud forming from grain, flour, powdered milk and sawdust etcetera.

The reason why dust will explode in such a condition but not when it a pile of dust is lit with fire is that in a dust cloud, every dust particle is in contact with air. This massively increases the surface area of the dust relative to its mass, meaning there more reactions can occur. In this case, the reaction is oxidisation of the substance, leading to combustion. This is why the finer the dust or powder, the greater the risk of an explosion. Even substances such as wood or aluminium can create an explosion when finely powdered enough.

The greatest casualty due to a dust explosion was in 1942 when a coal dust explosion in a Chinese mine killed 1549 miners. Another famous case was in 1878 when the Washburn “A” Mill in Minneapolis exploded, leading to the destruction of the world’s largest grain mill and five other mills. This reduced the city’s grain production to almost one-half.

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Voyager

Posted on by Jinavie

In 1977, NASA launched into space two unmanned probes named Voyager 1 and 2 respectively. These probes were designed to study Jupiter and Saturn and were not expected to function past this point. The original Voyager mission officially ended in 1989 when Voyager 2 did a close flyby of Neptune. However, as of 2014, both Voyagers are still travelling ever onward into interstellar space, sending back crucial data about our solar system and what is inside it, along with beautiful photographs of the planets.

The two Voyager probes greatly outlived their expected lifespan and exceeded what they were expected to do. Thanks to the Voyager program, we now have a far better understanding of our own Solar System, such as the fact that it is asymmetrical, or that Neptune had three rings. Voyager 1 is now the most distant man-made object from Earth – with its closest neighbour, Voyager 2, being billions of kilometres away from it. Yet it continues to strive onwards into the unknown, exploring the depths of space all alone.

The Voyagers also carry a golden record on which scientists recorded pictures, sounds and music (such as Bach and Mozart) that represented scenery found on Earth. It also includes various languages, mathematic formulas, a representation of our Solar System and our DNA, anatomy and reproduction. It is meant to be a time capsule of Earth, for our future descendants or whatever else may be out there.

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Silver

Posted on by Jinavie

Historically, silver has been associated with cleansing, healing, the moon and warding off evil. For example, it is said that some monsters such as werewolves would only die if it is shot by a silver bullet. The Greek goddess of hunting and the moon, Artemis, carries a silver bow. Although it is always seconded to gold when it comes to precious metals, silver is a fascinating metal.

It is the most reflective metal on Earth and has the highest conductivity for heat and electricity. It is ductile and malleable, making it a good choice of metal for making coins, jewellery and silverware (hence the name). Because of how reflective it is, it is also used in solar panels and special mirrors, such as those in telescopes.

Another useful characteristic of silver is its chemical reactivity. Thanks to this property, silver forms many different compounds with varying applications. Silver halides are photosensitive and turn dark when they are exposed to light. This is the basis of film photography, where the light shone on a film coated with silver halides leaves a photographic imprint. Silver oxides are sometimes used in batteries and silver/mercury alloys are used for dental fillings.

Silver also plays a role in medicine. Silver ions have been shown to inactivate bacteria such as E. coli, making silver nanoparticles a useful antiseptic that can be impregnated into different materials such as wound dressings. Silver nitrate sticks are used in emergency departments as applying it to a bleeding vessel in the nose will release nitric acid, which cauterises (burns off) the vessel to stop a nosebleed. In medieval Korea, silver spoons were used to test if a food has been poisoned with arsenic, as arsenic reacts with silver to form a black tarnish. If a person has too much silver build-up in their body, they can develop argyria (silver poisoning), which turns the skin an eerie bluish-grey colour.

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Posted in Science & Nature

Addition

Posted on by Jinavie

In the late 18th century, the great mathematician Carl Friedrich Gauss was given a punishment by his teacher for being mischievous. The punishment was this simple yet tedious problem: add every integer number from 1 to a 100.

Gauss, now referred to as the “Princeps mathematicorum” (Latin for “the Prince of Mathematicians”), came up with a simple shortcut and solved the problem without breaking a sweat. He realised that he could add two numbers from opposite ends of the range of numbers and get the same number e.g. 1 + 100 = 101, 2 + 99 = 101 etc. Using this logic, there must be a certain number of identical pairs of 101.

He then came up with the following equation:

100/2 x (1 + 100) = 50 x 101 = 5050

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Head Bobbing

Posted on by Jinavie

If you take the time to look at how most birds walk, such as a chicken or a pigeon, you will notice that they bob their heads. This seems extremely impractical as if we bobbed our heads like that, we would likely become dizzy and vomit quite soon. So why do birds do it and why does it not make them dizzy?

A major difference between birds and human beings is the way our vision works. In humans, our eyes are constantly moving at a rapid rate (saccade) to collate information and stabilise images. Even when we are walking and our head is moving around, our eyes use various sensory information and reflexes to fix our vision at one point, giving us a clear picture. This is such a powerful reflex that one test to check a person’s brainstem function (for example, when they are in a coma) is to move the head and see if the eyes stay fixed on a point or if they follow the head (doll’s eye test). If the brainstem is intact, the eyes will keep looking at a fixed point despite head movement.

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Birds on the other hand, cannot fix their vision this way. Instead what they do is they keep their head absolutely still in three-dimensional space when their body is moving. If you hold a chicken in the air and move the body around, you will find that the head stays stationary. This means that when they are walking, the bird’s head will stay still while the body takes a step forwards, then it will move to catch up to the body. From a third person’s point of view, this makes it look like they are bobbing their head, although they are just keeping it very still. In 1978, Dr Barrie J. Frost did an experiment where he put pigeons on a treadmill surrounded by a still backdrop and found that the pigeons did not bob their heads because there was nothing to see.

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