Tag: science

Posted in Science & Nature

Banana Equivalent Dose

Posted on by Jinavie

No form of energy has been more feared or creatively explored in science fiction (e.g. Godzilla) as radiation, yet the layman tends to know little about the actual properties and effects of radiation. The word “radiation” is commonly associated with things like Chernobyl, mutation and cancer. However, most people only know that radiation is “bad” while not knowing exactly how and why it is dangerous. Radiation is essentially high-frequency light which can deliver a large dose of energy (just like how microwaves cook food and sunlight can burn paper when focussed through a magnifying glass). When this high-dose of energy passes through living organisms, it damages the DNA in cells, potentially causing irreparable damage. This can lead to mutation and disruption of cell division (which can lead to cancer) or cell death (which is why radiation is ironically used to kill cancer cells).

The more technical question is “how much” radiation is harmful. For example, how much more dangerous was the Chernobyl incident compared to an x-ray? Like many other things in science, radiation is measured using an internationally universal unit called the Sievert (Sv). The radiation received from standing next to the Chernobyl reactor core after meltdown was 50Sv, while a chest x-ray is 20μSv (1000μSv = 1mSv, 1000mSv = 1Sv). Therefore, the Chernobyl incident could be considered to be as strong as 2.5 million chest x-rays. Although there is great variation, it is considered that a dose of 400mSv can cause symptoms of radiation poisoning, while 4~8Sv of radiation will lead to certain death.

Fascinatingly, radiation is not an uncommon thing. Radiation is all around us, with an average person receiving about 10μSv of background radiation per day just by living on Earth. Ergo, two days of walking around gives you the same amount of radiation as a single chest x-ray. A CT scan gives out a significantly greater dose of radiation at about 7mSv (approximately 350 x-rays or a year’s worth of background radiation).

However, the Sievert is a unit that is difficult to understand. Thus, some scientists devised a clever, humorous equivalent unit called the banana equivalent dose (BED). Bananas contain a certain amount of radioactive isotopes (radioactive potassium), making them technically radioactive. A banana contains 0.1μSv of radiation. Ergo, a chest x-ray is the equivalent to eating 200 bananas, a CT scan is 70000 bananas, while the Chernobyl incident gave people nearby a dose of roughly 500 million bananas.

The banana equivalent dose is a rather useful (and hilarious) way of comparing the danger of radiation from different sources. The next time you go to hospital for an x-ray, just picture 200 bananas being shot through your chest.

Posted in Science & Nature

Units

Posted on by Jinavie

In September of 1999, NASA ambitiously launched a Mars weather satellite. But the satellite did not even reach its destination, instead exploding in the atmosphere soon after launch. Why was this? The reason was so stupidly simple. The failure was because of units.

The satellite that was designed by Lockheed Martin was designed using the imperial system (pounds, feet and yards), whereas NASA’s systems used the internationally-used metric system. Because of this simple error, the pride of the USA space program fell to the ground and an astronomical amount of money was burnt to ashes in the air.

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Posted in Science & Nature

Wave

Posted on by Jinavie

One of the joys of going to a beach is listening to the breaking of waves. Waves are typically associated with the ocean, but can also form on lakes, rivers, canals or any body of water with a free surface. 

Waves are caused by wind blowing over the water surface, dragging it in a certain direction. As the wind only affects the surface, the water below rises to fill the space, causing a circular movement. This appears as a wave on the surface. The faster the wind blows, the more the surface is shifted and the bigger the waves become. Other factors that determine the wave size are: water depth, distance of water that the wind blows over (fetch), the width of the area of the fetch and the duration the wind blows over the area. Because of these factors, some lakes may be as wavy as the sea while others are completely tepid.

The waves formed by the wind merge to form bigger waves in the ocean. The resulting wave is known as a swell. When the swell reaches the shore, the depth of the water reduces, causing the wave to rise in height and become steeper. If the wave is high enough, the base becomes unstable and the wave collapses, which is what causes waves to break.

Although it sounds like a simple process, the consequences can be deadly. Wind waves can reach heights above 30m given that the conditions are right (usually during extremely serious storms). Such a wave can flip a cruise ship with ease like a rubber toy.

Posted in Science & Nature

Dihydrogen Monoxide

Posted on by Jinavie

Many people know about the dangers of chemicals such as lead and dioxin, but there is lack of awareness of an even bigger killed chemical: dihydrogen monoxide. It is a colourless, odourless, tasteless chemical that is responsible for the death of hundreds of thousands of people around the world.

Most deaths caused by dihydrogen monoxide (DHMO) are by accidental inhalation, causing cerebral hypoxia. However, the dangers of DHMO do not end there. Its solid form can cause severe tissue damage after prolonged exposure, and both its gas and liquid forms can cause severe burns. It is possible to overdose on DHMO, with symptoms ranging from excessive diaphoresis and micturition, bloating, nausea, vomiting and body electrolyte imbalance such as hyponatraemia. For those who are dependent on it, withdrawal means certain death. DHMO has also been found in various types of tumours biopsied from terminal cancer patients.

Not only does DHMO have consequences on human health, it is also damaging for the environment. DHMO is the leading cause of the greenhouse effect (surpassing carbon dioxide), a key component of acid rain, accelerated corrosion and rusting of many metals and contributes to the erosion of natural landscapes. DHMO contamination is a real, global issue, with DHMO being detected in lakes, streams and reservoirs across the globe. DHMO has caused trillions of dollars of property damage in almost every country, especially in developing nations.

Despite the danger, DHMO is commonly found in the household, in the form of additives in food and drinks, cleaning products and even styrofoam. There are no regulation laws for DHMO and multi-national companies continue to dump waste DHMO into rivers and the ocean. It is astounding to see such a deadly chemical go unregulated.

If you have not caught on by now, dihydrogen monoxide’s chemical formula is H2O – also known as water. Technically speaking, there are no false statements in the above description. But even children know that water is not only (relatively) safe, but necessary for life. The report on “dihydrogen monoxide” originates from a 1997 science fair project by Nathan Zohner, who was 14 years old at the time. His project was titled “How Gullible Are We?” and involved presenting his report about “the dangers of DHMO” to fifty school students to see what their reaction would be. 43 students favoured banning it, 6 were undecided and only one recognised that DHMO was actually water. Even more surprising is that there are cases (such as in California in 2004), where city officials came close to banning the substance, falling for the hoax. This goes to show how gullible people can be in the face of what they do not know.

Posted in Philosophy

Black Cat

Posted on by Jinavie

Philosophy is like being in a dark room and looking for a black cat.

Metaphysics is like being in a dark room and looking for a black cat that is not there.

Theology is like being in a dark room and looking for a black cat that is not there and shouting “I found it!”

Science is like being in a dark room and looking for a black cat using a flashlight.

Posted in Science & Nature

Honeybee Dance

Posted on by Jinavie

How do honeybees share the location of a food source, such as a flower, to other bees of their colony? An Austrian biologist named Karl Von Frisch devised an experiment to learn how the honeybees communicated with each other. He set up two different food sources and tagged every bee that came to pot A green and bees that came to pot B red. He then studied the behaviour of these bees back at the hive. What he discovered was fascinating.

For millennia, beekeepers have noticed that some honeybees have a tendency of moving in a peculiar yet methodical way once they returned to their hive after foraging for flowers. The bees would move in a straight line while waggling their bottom (moving side-to-side), then walk in a semicircle back to where they started. They would then waggle in the same direction, then move in a semicircle on the opposite side, completing a figure-eight path. This is called a waggle dance.

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Frisch noticed that bees with green spots and the bees with red spots both did the waggle dance once they returned to the hive, but in different directions. All bees with green spots danced so that the straight line pointed a certain direction, while the bees with red spots danced the same dance except pointing another direction. Amazingly, the angle between these two directions was exactly the same as the angle separating pot A and B (with the hive as a point of origin). Frisch deduced that the waggle dance was the language of honeybees.

Through further experimentation, Frisch was able to tease out the details of this “language”.

  • Honeybees’ eyes can see ultraviolet and polarised light, which allows them to see where the sun is in the sky at all times. This is because sunlight polarises so that it points towards the sun and honeybees can see this direction. Therefore, the bee’s eyes act as a solar compass that tracks the exact location of the sun in real-time.
  • Bees have a finely-tuned internal clock that allows them to predict exactly where the sun should be depending on time, season and latitude, as the sun moves through the sky.
  • Another point of reference that is used in the bees’ language is gravity. Gravity is a constant that does not change, meaning all bees know which direction is “up” and which is “down”. This also means they can use a vertical, perpendicular line as a standard zero-point.

By pairing the two global constants, gravity and the location of the sun, the bees can accurately signal to other bees the direction they should fly in to find the food source. If a bee does a waggle dance that points 60° right from the vertical “up” direction (as defined by gravity), it signals that the bees should fly 60° right from the direction of the sun. If the angle is 0°, the bees should fly directly towards the sun, and if the angle is 180°, the bees should fly directly away from the sun. The bees use their internal clock to calibrate the direction depending on the time of the day.

The straight line “waggle” part of the dance gives the information of distance. The longer the duration of the straight line, the further away the flower is. As a general rule of thumb, the duration of the straight line increases by 1 second for every 1 kilometre. When the food is within about 60m of the hive, the 8-shape waggle dance turns into an O-shape round dance. The bee deduces the distance by the energy required to fly to the location.

By encoding the two variables “direction” and “distance”, a bee can effectively use the waggle dance to accurately pinpoint the location of a food source. It is amazing to see that animals that we consider “primitive” such as bees have such an intricate method of communication.

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(Image source: http://aireona93.deviantart.com/art/YAY-Waggle-Dance-146361214?q=boost%3Apopular%20waggle%20dance&qo=1)

Posted in Science & Nature

Folding Paper

Posted on by Jinavie

Take any piece of paper and fold it in half. Then fold it in half again. Chances are, you will not be able to fold the paper more than seven times. Try it. No matter how thin the piece of paper is, it is extremely difficult to fold a piece of paper in half more than seven times. The reason? Mathematics.

A standard sheet of office paper is less than 0.1mm thick. By folding it in half, the thickness doubles and becomes 0.2mm. Another fold increases it to 0.4mm. Already, the problem can be seen. Folding a paper in half doubles the thickness, meaning every fold increases the thickness exponentially (2ⁿ). By seven folds, the thickness is 2 x 2 x 2 x 2 x 2 x 2 x 2 = 128 times the original thickness. This makes the piece of paper so thick that it is “unfoldable”.

Another limitation is that folding the paper using the traditional method means the area also halves, decreasing exponentially. With a standard piece of paper, the area of the paper is so small after seven folds that it is mechanically impossible to fold it. Furthermore, the distortion caused by the folds is too great for you to apply enough leverage for folding the paper.

Could these limitations be overcome by using a larger piece of paper? Sadly, no matter how large the piece of paper, it is impossible (or at least extremely difficult) to fold a piece of paper over seven times. This has been a mathematical conundrum for ages, until it was solved in 2002 by a high school student named Britney Gallivan. Gallivan demonstrated that using maths, she could fold a piece of paper 12 times. The solution was not simple though. To fold the paper 12 times, she had to use a special, single piece of toilet paper 1200m in length. She calculated that instead of folding in half every other direction (the traditional way), the least volume of paper to get 12 folds would be to fold in the same direction using a very long sheet of paper.

Mathematics, along with science, is what makes something that seems so simple, impossible.

Posted in Science & Nature

Metal

Posted on by Jinavie

Next to the discovery of fire and the wheel, the discovery of metals and the mastery of metalworking was arguably one of the most important advances for prehistoric humanity. Metal was far superior to rock, clay, wood or any other natural resource known to man in terms of strength and sharpness. Because of these properties, metal soon became a valuable commodity. It can be seen how much impact metal had on humanity’s history, considering that the stages of human prehistory were named after the type of metal (or lack thereof) that was mastered then: Stone Age, Bronze Age and Iron Age.

The discovery of metal came in two ways.

One was through mining, where prehistoric people discovered that shiny, hard objects were buried in the ground. They later discovered that with enough heat, they could melt the metal out of ores (copper and tin were the first metals to be gathered this way) and mould them into any shape. After smelting technologies developed, our ancestors found that mixing copper and tin produced bronze – a much stiffer and more durable metal than either of its components. A mixture of metals is called an alloy. This was the start of the Bronze Age. Bronze was extremely useful and people quickly came up with innovative ways of using it, such as farming equipment and weapons.

Some other metals used during this age were: gold, silver, lead and mercury. It is likely that gold was one of the earliest metals used as it comes in pure nuggets and is easily workable thanks to its chemistry. However, given that gold is rather soft and was treated more as jewellery than a practical metal, it was not used as much to advance technology.

The second way mankind came upon metals was in the form of “gifts from the gods”. A prime example is iron. Although the Iron Age began around 1200BC at the earliest, there are iron objects (mainly jewelleries) that have been dated back to 5000BC. How could this be? This was before mankind had the technology to smelt iron ores (which is more difficult and needs much higher temperatures than copper or tin ores), so the iron could not have been gathered through mining. The answer to this conundrum lies in meteorites. About 6% of meteorites contain iron and nickel, which prehistoric civilisations may have stumbled onto and taken the shiny pieces back to their tribe. The people would have considered the gathered iron a “gift from the gods”, as it had crashed down from the “heavens”. Because of this reason, iron was considered more valuable than gold or silver and was frequently used for jewellery. This is reflected in Arthur C. Clarke’s science fiction short story, The Songs of Distant Earth, where sentient sea scorpions hoard metal objects stolen from the humans and wear it proudly as a badge of honour.

The history of iron and how it was believed to be a gift from the heavens relates to a common superstition of how finding a penny (or any coin) represents good luck. As “metal” (mainly iron) was considered a holy gift bestowed unto mankind, finding a piece of metal was believed to be a blessing and some form of protection against evil. This is also represented in various traditions such as hanging horseshoes over doorways and wearing charm bracelets with metal on it.

Although it sounds like a silly superstition, it clearly shows how metals have been an integral part of the development of civilisation.

Posted in Psychology & Medicine

Reaction

Posted on by Jinavie

If you were walking along the street and found a bird lying on the ground, how would you react? You would probably poke the bird to see if it is alive. We have a peculiar habit since we are children of poking living things that we see for the first time. Through poking, we discover whether it is alive or dead, soft or hard, slimy or furry, docile or aggressive.

Prompting a reaction and observing the reaction is a surprisingly useful way of learning. In chemistry, we react an unknown substance with other chemicals to discover its identity. In medicine, we stimulate parts of the brain with electricity to discover what each part does. In physics, we build giant accelerator to crash particles together to find out their constituents and properties. If you fell into a cave so dark you cannot see even one foot ahead of you, the best way to find out if there is a wall or a hole or water ahead of you is throwing a rock in that direction.

This principle can be applied to psychology. To learn how people around you behave, provoke them. Human beings are extremely sensitive to stimuli and even when they consciously try to hide it, they will subconsciously react. If you keep (subtly) poking the person, you will soon be able to predict how they will react to something, what actions they will take, and you may even discover what is on their mind.

We cannot see the wind, but we can infer that it exists because the leaves blow. The best way to prove something that you cannot see inducing and looking for reactions.

Posted in Science & Nature

Verneshot

Posted on by Jinavie

If there is one thing we learn about dinosaurs, it is that they were wiped off the face of the Earth by an asteroid impact. Another feasible theory is that a supervolcano eruption completely destroyed the ecosystem, wiping out all life on Earth by either directly destroying them via a massive shockwave (if they were within range), or by slowly starving them as the resultant plumes of smoke would have blotted out the sun for years. But interestingly, scientists looking back over some extinction-level events of the past, discovered signs of both an asteroid strike and a volcanic eruption. This sounds to be extremely implausible, as the odds of both happening in the same era are near impossible (unless there is some extremely vengeful deity that hated the dinosaurs).

One theory that tries to explain all of this is the verneshot theory. To better understand the concept of a verneshot, imagine a cartoon character such as Yosemite Sam (the beloved red-bearded, gunslinging cowboy character on Looney Toons) shooting his gun wildly into the sky. Cartoon logic dictates that his bullets will eventually fall back on some unwary bystander. Now imagine if the Earth did the same thing, but instead of a bullet it shoots a giant piece of rock capable of causing mass extinction into the sky.

A verneshot occurs in a similar way a supervolcano erupts, where there is an incredible build-up of super hot molten rock. A supervolcano would be when this molten rock erupts as lava. In the case of a verneshot, massive amounts of carbon dioxide build up instead, leading to a pressure build-up under the crust. When the pressure becomes too much, the crust explodes, with the piece (of indeterminate size) being rocketed into space. However, the giant rock does not end up in space. Instead, it is only launched to a sub-orbital altitude, meaning it will come crashing back down to Earth due to gravity. Thus, a verneshot is when a volcanic eruption acts as a giant cannon to launch a piece of the Earth into the sky, which falls back to Earth as an asteroid-like object.