Posted in Science & Nature


Dragons are fantastic creatures of our imaginations, so they do not follow many of the rigid laws of natural science. They breathe unlimited amounts of fire, can endure extreme heat and they can fly despite their massive size. But perhaps the most unrealistic feature of dragons is the fact that they have an unnatural number of limbs.

All vertebrate animals on Earth follow a simple rule: they are four-legged creatures, also called tetrapods. The limbs may have devolved away such as in whales and snakes, but they remain as vestigial structures or still encoded for in the genes. Birds and bats have adapted their upper limbs into wings to fly, but the total number of limbs is still four.

How many limbs does a dragon have? They have four legs that they stand on, but also two large membranous wings like a bat. This means that they have a total of six limbs. The only other animals that share this trait are insects and other mythical creatures such as the centaur and pegasus.

To be a vertebrate with six limbs, a dragon must have evolved from an ancestor separate to Tetrapodomorpha, an ancient fish-like creature with four limbs that is the common ancestor to all four-legged beasts. Alternatively, the wings may not be true “limbs” and be similar to flying lizards that evolved to have a rib jut out with a membrane attached to act as a glider.

Unlike the scientifically inaccurate dragon, a wyvern obeys nature’s four-leg rule. Furthermore, unlike the traditional Western dragon that we have been describing, dragons of the Far East have no wings and four limbs, also obeying the law.

As ridiculous as it may sound, applying scientific principles to our imagination allows us to learn more about how our world works.

Posted in Science & Nature


Death by lava is an often-used trope in films, most likely because of its slow, dramatic nature and the poetic beauty of being engulfed by liquid fire. But unfortunately as with so many things in the film world, most movie scenes depicting a person slowly sinking into lava until they are completely submerged is completely unscientific.

Lava is essentially molten rock. Just as ice and rock have different densities (try smashing two together for comparison), water and lava have completely different densities. In fact, lava is just over three times denser than water and somewhere between 100,000 to 1,000,000 times thicker (viscosity). The extremely high viscosity is why lava does not flow well, much like thick syrup and pitch. Density matters because less dense objects float when placed in a denser substance. Human beings are slightly denser than water (1010kg/m³ vs 1000kg/m³), meaning we can float if we have enough air in our lungs to provide the buoyancy. However, we are far less dense than molten lava. Even if we were as dense as lava, the extreme viscosity would make it very difficult for us to sink as the lava would not flow away from you that quickly. Ergo, if you were thrown into a pool of lava, you would not sink into a dramatic death.

Instead, you would most likely experience an even more horrific death as you stay afloat on the lava, as the surface of your body touching the lava is burned. Typical lava is between 1100~1200°C – well beyond the ignition point of human flesh. Not only will the skin, fat and muscle melt and peel away, but it will light up like a wick. The flame will soon cover the entire person and they will not only burn, but combust. Ultimately, only ash and completely dried up bone will be left floating on the lava, which will also end up igniting eventually.

Unfortunately, objects made of material such as steel and most other metals are denser than lava. This means that the Terminator would actually sink as dramatically as it did in the ending of Terminator 2 if he were to descend into a pool of lava.

(NB: It is important to note that in the movie, he descends into a vat of molten steel, not lava. Therefore, the accuracy of that scene hinges on whether the Terminator is made of a metal alloy denser than molten steel)

Posted in Science & Nature

Dihydrogen Monoxide

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.

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Folding Paper

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.

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Giant Monster

A gigantic dinosaur monster of 50m height and 20000t weight appears in the centre of Tokyo! The invasion of giant spiders! These are common scenarios in science fiction films. Mankind has always been fascinated by giant creatures. Whether it be a child or an adult, no one passes by the skeleton of a Tyrannosaurus rex without being awestruck. Thus, it is very easy to use such creatures in movies. But the key point of every monster movie is the “stats”. A height taller than a high-rise building and a weight nearing one of a battleship excites people before the movie even starts. The problem is that this is very unscientific (considering it is a “science fiction”).

Let us look at the dinosaur monster first. The moment the monster steps on to land, it will be crushed like tofu. Every structure in its body will collapse and the skeleton will give way, causing 20000t of meat to crash to the ground. Simply put, the monster is just too heavy. Let us hypothesise that the monster is the shape of a gigantic T-rex. Tyrannosaurus rex was 15m tall and weighed 7t. If a 15m dinosaur is stretched to the height of 50m, the height becomes 3.3 times the original. But as the width and depth need to be expanded by 3.3 times as well, the weight becomes 37 times the original. The question is whether the monster can support its own weight. Just as the volume increased by a factor of 37, the cross-sectional area of every part of the body increases by a factor of 3.3 x 3.3 = 11. As muscle strength is directly proportional to the cross-sectional area, the strength only increases by 11 times. Thus, the load on a creature’s body is the same as the factor of expansion (e.g. there is 3.3 times the load on the monster’s muscles). But this is only when the T-rex was simply stretched. According to the stats, the monster weighs 20000t – 2800 times the weight of a T-rex. To support 2800 times the weight with 11 times the muscle, the load on the bones and muscle is 250 times. This is equivalent to having 249 people the same weight as you on your back. Of course, the monster cannot support this and its bones will become crushed and its internal organs will all burst, causing instant death.

Similarly, a giant insect monster also receives the same load as its expansion. But unlike an animal, insects have an exoskeleton instead of a skeletal system. This structure cannot support the load caused by the expansion (also, if you stretch an ant that is not even 1cm to just 10m, the load becomes over a thousand times). Ergo, the monster will collapse instantly. A giant monster is an unscientific creature that can only exist in our imagination.

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Titanic is a film telling the story of the sinking of the eponymous ship, the RMS Titanic, directed by James Cameron in 1997. Most people are entranced by Leonardo DiCaprio and Kate Winslet’s excellent acting, the cutting-edge special effects and the waves of emotions that it projects to the audience, but there is another component that is just as amazing.
Most films and television shows tend to sacrifice science in the name of drama. Thus, science fiction movies are ironically quite inaccurate in even the most basic scientific facts. However, Titanic is strangely true to science despite being a drama film.

To start with, we can take the scene where Rose, embraced by Jack from behind, spreads her arms wide open like wings while on top of the stern of the Titanic. Here, Rose is seen standing so high that she is above the rails from the thighs up. In this position, even a slight push would cause her to lose balance and make her fall, causing the movie to end prematurely. But on closer inspection, it can be seen how Jack has his arms wrapping under the cables. To be so attentive to detail even in the moment of heated passion – Jack is surely a calm, cool-headed man.
In the scene where the Titanic is sailing, it takes 25 seconds for the ship to completely pass a point. Considering that the ship was 269m in length, this comes to a cruising speed of 38km per hour. This is 21 knots when converted – almost identical to the actual cruising speed of the Titanic which was 22 knots.

The movie is accurate in even finer details. Let us study the climactic scene of the sinking. When the ship is tilting at its highest point, a person took 4.3 seconds to fall and hit the water. This equates to a height of 91m, which can be achieved by a 269m ship tilting at about 40 degrees.
When Jack is bound by handcuffs, Rose bravely cuts the chain with an axe. But can a fair 18-year old girl summon such strength? If the chain is the thickness of two 5mm diameter metal rings, then the blade requires 49 Joules of energy to cut the chain. To achieve this, a 3kg axe must be swung at the speed of 20km/h, which is the same as dropping the axe from a height of 1.6m. Ergo, Rose can create enough energy simply by adding a little more strength to the axe as she swings it down from above her head.
Lastly, in the tragic scene where Jack sinks away, he disappears in 6.4 seconds. If by a rough estimate he sank about 2m, then it suggests that he descended at about 1/100 strength of free falling. This means Jack’s body density is about 1% greater than sea water. As the density of sea water is 1.04g per 1cm3, this is perfectly reasonable assuming that Jack is big-boned.

A film focussing on such fine scientific detail can certainly be called a masterpiece of the century. If only Rose’s voice did not echo in the final scene…

Posted in Science & Nature

Star Wars

Star Wars is packed to the brim with epic scenes of starship dogfights. The many “pewpews” of laser cannons and massive explosions characterise this classic science fiction film series. However, this is an example of a classic “unscientific fiction”.

The great explosions of ships would never generate a loud sound as in space, there is no air or any medium to carry the sound waves. As the tagline for the movie Alien states: nobody can hear you scream in space.
In this regard, 2001: A Space Odyssey is most accurate in its portrayal of space. Not only does it have absolute silence during its scenes outside in space, but it also has accurate portrayals of space-science such as magnetic boots and rotating toilets to generate gravity.