Posted in Science & Nature

Shooting Star

When an object from outer space enters the Earth’s atmosphere, it starts to burn up and creates a brilliant streak in the sky, which we call a meteor or shooting star. Contrary to popular belief, this is not due to friction with the air in the atmosphere.

An object entering the atmosphere is typically travelling at extraordinary speeds. Most meteors are travelling around 20km/s (or 72000km/h) when they hit the atmosphere. At these speeds, air molecules do not have a chance to move out of the way. The meteor will instead collide into the air molecules, pushing them closer and closer to each other, compressing the air in front of it.

As we know from physics class, compression increases temperature in gases as per the ideal gas law (PV=nRT). The impressive entry speed of these meteors result in so much air compression that their surface can heat up to 1650 degrees Celsius.

The heat boils and breaks apart the contents of the meteor, turning it into superheated plasma that gives off a glow. This is the streak of light that we see in the night sky when we wish upon a shooting star.

Posted in Psychology & Medicine

Viscera: Lungs

(Learn more about the organs of the human bodies in other posts in the Viscera series here:

Everyone knows that we need oxygen to survive. The way we get oxygen from the atmosphere is through our lungs – the organ where gas exchange takes place. The pair of lungs take up a large proportion of the chest cavity and they link up with each other to form the trachea (windpipe). The left lung is slightly smaller to accommodate for the heart.

The lung is extremely soft and light, so much that it floats on water. It is essentially made up of an intricate tree-like system of airways, which become narrower and narrower as it divides out from the trachea. Since every airway divides up, the number of airways increases exponentially. Every bronchiole (small airways) ends in a bubble-like sac called an alveolus. Because of the sheer number of alveoli, the lungs actually have a total surface area the size of a tennis court. To picture this, scrunch up a piece of newspaper into a ball to pack a large surface area into a small space. The massive surface area allows for enough gas exchange to occur to give us the oxygen we need and excrete all the carbon dioxide we produce.


When we take a breath in, the chest cavity expands and stretches the lungs in all directions because of the negative pressure (like a vacuum). Air fills the airways all the way to the alveoli. The alveoli are extremely thin; so thin that the oxygen in the air effortlessly seeps through into the blood vessels that surround the alveoli. On the other hand, carbon dioxide seeps out of the blood into the alveoli, which is then breathed out as the muscles of your ribcage contract to force the air out. This process is called gas exchange and is driven by diffusion – the movement of particles from an area of high concentration to an area of low concentration (like how dye spreads throughout water).


It is well-known that smoking is bad for your lungs. This is because of two major reasons: COPD and lung cancer. COPD (chronic obstructive pulmonary disorder) is when your lungs become so damaged by smoking that they cannot function, leading to hypoxia (lack of oxygen) and hypercapnia (excess of carbon dioxide). Smoking causes inflammation in the lungs, which causes airways to shut down from swelling and mucus, while destroying the fine walls of the alveoli. This causes the alveoli to thicken from scarring and less elastic due to the destruction of elastic tissue. Ultimately, the lungs become hyperinflated as the patient cannot breathe out air properly and the lungs are not elastic enough to return to their original shape and size. Ergo, the patient becomes progressively breathless, gasping for breath as they suffer a sensation of impending death as the carbon dioxide level builds and the oxygen level falls.

Posted in Psychology & Medicine


What would happen if your nostrils were facing up instead of down? Rain would fall into your nose and when you were sad or with a cold, mucus would fill up in the nose instead of draining, creating quite a problem. Then why do we have two nostrils? The reason being, if one is blocked, we can breathe through the other (unless you have bad hay fever or a cold and both are blocked). This shows how (almost) every part of the human body has a purpose, including its shape and characteristics.

Another fun fact about nostrils is that at one moment, only one nostril is used for breathing. In other words, you can breathe easily through one side of your nose but the other side will feel stuffy and blocked. This phenomenon alternates sides on a periodic cycle (where the blocked side becomes clear and vice versa). This mechanism is most likely to protect the inside of your nose (nasal cavity) from drying out.

Posted in History & Literature

Elements: Four Elements Of The West

Human beings have believed that all matter can be divided into basic elements for a very long time. Although we now know that the basic building block of the universe is atoms, what did ancient people believe matter was made of?

In ancient Greece, the seat of Western culture, it was believed that everything was made from the four elements: earth, fire, water and air. According to Aristotle, every element has a primary and secondary characteristic, with the four characteristics being hot, cold, dry and wet. Air is primarily wet and secondarily hot, fire is primarily hot and secondarily dry, earth is primarily dry and secondarily cold and water is primarily cold and secondarily wet. He also spoke of a fifth element (quintessence) beyond the four elements. The name of the fifth element is aether and it is a pure and heavenly element that cannot be corrupted like the earthly four elements. Furthermore, it was thought that aether was the element of the sky and stars were composed of it as they were heavenly, not earthly.

The four classic elements of ancient Greece had an impact not only on physics and chemistry, but also on philosophy and culture (the concept of the four elements is popular in modern games too). The most interesting example of these is a theory by Hippocrates, the father of Western medicine, that states that the human body is composed of four bodily fluids (humours) and an imbalance between the humours caused diseases. The four humours are yellow bile (fire), black bile (earth), blood (air) and phlegm (water). Furthermore, he believed that the four humours affected personalities too. For example, an excess of black bile (“melan chole” in Greek) would cause a person to become introspective and think negatively, leading to depression or “melancholy”. This is quite possibly the first medical records on clinical depression.

The four classic elements of ancient Greece can also be found in ancient Egypt and many other ancient civilisations. It also had a significant influence on alchemy in the Middle Ages.

(Image source

Posted in Science & Nature


Every creature on earth knows the fearful power of fire. Learning how to utilise it is possibly one of man’s greatest achievements, as it allowed science and technology to kickstart in every way. However, we still lose control over it sometimes and suffer the consequences. Fire can develop from a tiny ember to a full-blown firestorm that incinerates everything in its path. The following are the four stages of fire development:

  • Stage 1 – Incipient stage: No visible smoke and very little heat. Small fire.
  • Stage 2 – Build-up stage: More heat causes pyrolysis (decomposition of material due to heat), releasing combustible gases. May cause a flashover (every combustible surface in the room ignites all at once).
  • Stage 3 – Fully-developed stage: Visible flame, massive amounts of heat, smoke and toxic gases. Everything is burning.
  • Stage 4 – Decay stage: Fire is either contained or extinguished. If not, may spread to other areas (e.g. the next room).

After sufficient heat has built up, fire spreads almost explosively (sometimes literally) causing extensive damage. Thus, the most important part is preventing the fire in the first place or extinguishing a small fire still at the incipient stage. As powerful a tool it may be, it can also destroy everything you hold precious within a matter of hours.

An interesting phenomenon related to fire is backdrafts. This is similar to flashovers (described above) except it is triggered by oxygen rather than a build-up of heat. Both cause a sudden transition from a small fire to a full-scale inferno.
A backdraft occurs when a burning room is filled with pyrolysed, combustible gases but lack the oxygen needed to continue burning as it was used up while the fire was building up. When a firefighter or a broken window causes air to rush into the room, the pressure in the room spikes and every combustible material suddenly bursts into flames, exploding out in a ball of fire. Backdrafts are one of the most dangerous fire phenomena that claim the lives of countless firefighters.

Posted in History & Literature

Black Death

This disease, also known as Pest or the bubonic plague, was a vicious infectious disease that decimated medieval Europe. It is caused by the bacteria Yersinia pestis, usually transmitted by fleas. The symptoms vary from high fever, malaise, nausea and vomiting, headaches, muscle cramps, seizures, red rashes, coughing and swollen lymph nodes, and causes death within four or five days without treatment.
People did not know about the existence of bacteria back then (it would be 200 more years until Louis Pasteur would suggest germs as the cause of infections). Back then, they considered diseases to transmit through miasma, or bad air. Also, they believed that to prevent transmission, they required a stronger smell to counter it.

Plague doctors, who treated according to the miasma theory of disease, wore a special set of equipments that were known as beak doctor costumes. They wore an overcoat, hat, gloves and boots made from waxed leather, carried a cane to assess the patient and point things out, and a peculiar mask. The mask had a long beak like a bird’s, giving the doctors the nickname beak doctors. The masks had round, glass windows to see through, and two small nostrils at the end of the beak.

Why did they wear this strange mask? The beak was hollow and doctors filled it with flowers, herbs, vinegar and incense that produce a strong smell, so as to “purify” the air coming through the nostrils. 
Although the miasma theory has been falsified by germ theory, this gear was the first hazmat suit in history.

There is another fascinating fact regarding the Plague, miasma theory and beak doctors. It regards the nursery rhyme, Ring a Ring o’ Roses:

A pocket full of posies; 
Atishoo! Atishoo! 
We all fall down. 

This nursery rhyme actually describes the Plague. The ring of roses refers to the red rashes and swelling of lymph nodes – a symptom of the Plague; the posies were herbs used to counter the miasma; coughing and sneezing were end-stage symptoms before death, which is shown in the final line. 

Posted in History & Literature


Mayday is the universal phrase for requesting emergency assistance in a crisis situation on the sea or in the air. 

It was first created by Frederick Stanley Mockford, who was a senior radio office trying to figure out a simple distress call sign. As he worked at Croydon Airport, London, and dealt with traffic mainly between England and France, he decided on the word mayday, which is derived from the French words venez m’aider, meaning “come help me”.

Another famous distress call is SOS, or  … – – – … in Morse code. It was first used by German radios but then became the worldwide standard in 1906. Although it is often thought to stand for “save our souls”, it is in fact a backronym that was made decades after it came to be. Instead, it was chosen as it is simple to remember (the backronym may have been devised to help people remember the letters) and easy to signal via Morse code. It was most famously used by the RMS Titanic

The reason why mayday was created (and set as a standard in 1927) was due to the need for a spoken word as the audio radio transmitters were developed.

Posted in Science & Nature

Rule Of Threes

This is how long you can survive for without certain things:

  • 3 minutes without air
  • 3 hours without shelter
  • 3 days without water
  • 3 weeks without food
  • 3 months without hope