Tag: science

Posted in Life & Happiness

Sunset

Posted on by Jinavie

Why is the sky blue in the day, yet it becomes dyed bright red at sunset? The reason is that the atmosphere splits white light into the colours of the rainbow like a prism. Short-wavelength colours such as blue and green tend to scatter more, making the sky blue usually. But as the sun sets, the angle at which sunlight enters the atmosphere changes and the light has to travel through more atmosphere before hitting Earth. The more the light travels, the more it scatters and blue-green light is scattered so much that it can no longer be seen. At this stage, the dominant remaining colour are orange and red, which have longer wavelengths.

But this alone would only give the sky a dull red colour. The brilliant splash of red and orange across the sky every evening is thanks to the scattering of light in a certain way by cloud droplets and other particles. This is why an exceptionally bright orange sunset can suggest rain the following day.

A “perfect” sunset requires the alignment of various factors such as the angle of the sun (affected by time and season), humidity, temperature, air component and the surrounding landscape. Depending on these factors, the sunset can range in colour from a deep red to a bright orange, to a pastel yellow to baby pink or purple (or at worst, a piddly dull yellow light). This means that a perfect sunset tends to only happen at a single moment in time when these factors align to your preference.

The corollary to this is that a perfect sunset is always a fleeting moment. No matter how much you want to hold on to it, time marches on and the sunset slowly fades away. It is futile to stop the moment from passing – to cling to the beauty of the moment. All you can do is enjoy that single moment while you can. It is a time when the past day comes to a close, while the future is getting ready to start. In that moment, do not think about the past or the future – just focus on the present. Take in the brilliant colours with your eyes. Listen to the chirping of the birds returning home. Feel the cool breeze brush past you. When the sun finally sets, despair not the passing of the beautiful moment, but cherish the fact that you had such a great moment. Because as you know, another sunset awaits you tomorrow.

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Posted in Science & Nature

Sonic Boom

Posted on by Jinavie

When something moves through the air, it pushes the air in front and creates a sound. This sound spreads as a wave at the speed of 340m/s (1225km/h). As the object moves, it makes a series of pressure waves, which is why the Doppler effect happens. These pressure waves look like rings that are squashed to the side the object is moving towards. As the object moves faster, the more compressed these rings become. When the object moves at the speed of sound (340m/s), the pressure waves all overlap as the object makes a pressure wave on the same place as where the last wave reached. This is the sound barrier.

At this point, there is so much overlap of the waves that a shockwave is formed. This shockwave – made of compressed air – travels at the speed of sound (Mach 1) and originates from the front tip of the object (e.g. nose of the plane). If the object moves any faster than the speed of sound, the new wave is made even before the old wave has propagated that far. The rings are now no longer in a nice concentric pattern, but instead form a shockwave cone. Sometimes this can be seen physically if there is enough condensation in the air to create a vapour cone. The sudden change of pressure from the shockwave creates a large booming sound, which we call a sonic boom (in fact, there are two booms due to the pressure difference at the tail too).

Sound, like other waves, is a form of energy. Hence, the shockwave formed by breaking the sound barrier can cause physical damage. If a fighter jet were to fly over a building at low altitude at supersonic speeds, it may cause windows to shatter and people’s eardrums to rupture. The shockwave creates a significant problem in aircraft design, for if a plane’s wingspan is wider than the width of the shockwave cone, its wings will snap off. This is why fighter jets and the Concorde have a characteristic sleek, triangular shape. The faster the plane travels, the narrower the shockwave cone becomes and the thinner the plane’s wingspan has to be.

Then what was the first manmade object to break the sound barrier? The answer is surprisingly old and simple – a bullwhip. The crack from a whip is actually a small sonic boom made by the tip of the whip travelling beyond the speed of sound.

Posted in Life & Happiness

The Perfect Toast

Posted on by Jinavie

Toast is one of those simple meals that anyone can make. Bread goes in, toast comes out. But some scientists decided to embark on a quest for the “perfect” toast. After spending a week toasting and tasting over two thousand slices of toast, the scientists came up with some figures.

The perfect toast should be:

  • 14mm thick
  • Made from pale-seeded loaf of bread taken from a fridge at 3°C
  • Cooked in a 900-watt toaster set to 5 out of 6 power
  • Cooked at a temperature of 154°C evenly from both sides
  • Cooked for exactly 3 minutes and 36 seconds (216 seconds)
  • Transferred gently to a plate that is pre-warmed to 45°C
  • Immediately slathered with 68.2mg per square centimetre of butter
  • Sliced once diagonally

The result of this formula is a perfectly golden-brown toast of 12:1 exterior to interior crispiness, with the “ultimate balance of external crunch and internal softness”.

Posted in Science & Nature

HeLa

Posted on by Jinavie

In February 1951, a woman named Henrietta Lacks was diagnosed with cervical cancer. The cancer was aggressive and her health quickly deteriorated, until her ultimate demise in October 1951. Although Henrietta Lacks passed away on that day, not all of her was dead. A scientist named George Otto Gey succeeded in culturing (growing on a petri dish) the biopsied cervical cancer cells, provided by Lacks’ physician. He discovered that this lineage of cells could keep dividing and growing without stopping. In the human body, cells will eventually reach a limit of dividing and be destroyed. The cells from Henrietta Lacks, however, were immortal. Gey named this cell line HeLa, taking the first two letters of Lacks’ first and last names.

The HeLa cell line (and all other immortal cell lines since) have proven very useful in research as they give an infinite supply of identical cells, giving scientists a model template they can experiment on. The immortality of the HeLa cells is such that 60 years later, scientists are still using cells from that lineage – cells virtually identical to the cells taken from Henrietta Lacks (save for random mutations that happen in any cells). The cells are so well-adapted to unlimited growth that they are sometimes considered a laboratory “weed”, because it can easily invade another cell culture and completely take it over. One biologist even went as far as claiming that HeLa cells were no longer human, but instead a new species. He supported his claim with the fact that HeLa cells are self-sufficient and can reproduce on its own, and that it has a different genome (even chromosome numbers) to human cells due to the nature of cervical cancer.

The main issue with HeLa cells is the ethics behind it. At no point did Lacks or her family give permission to the doctor for him to donate her cells for research. Since her death, the cells were not only used for the purpose of pure research, but also commercialised. Unfortunately, medical ethics was not well-established at the time and asking the patient’s consent for such things was not common. The two major sides in this debate would be the unethical act of taking human tissue and using it without consent, versus the potential benefit it brings. For example, HeLa cells were used by Jonas Salk for his research that led to the development of the polio vaccine. It may be a stretch, but if those cells were not taken from Lacks, the development of the polio vaccine may have been delayed and countless more people would have suffered from a lifelong crippling illness. This is the great question in medical ethics: how much of an individual’s human rights can we afford to sacrifice for the needs of the many? Do the needs of the many really outweigh the needs of the few, or the one?

Posted in Science & Nature

Lava

Posted on by Jinavie

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

Shared Bodily Warmth

Posted on by Jinavie

Body heat is a vital condition that animals need to survive. It is so vital that when you are hypothermic, your body will override almost everything else to conserve heat as much as possible. Without enough heat, the chemical reactions that fuel your cells will grind to a halt and you will die. To solve the issue of getting heat, nature came up with two answers: endotherms and ectotherms.
Endotherms are organisms that produce their own heat (e.g. mammals) by trapping the heat produced by metabolism and through extra mechanisms such as shivering. Ectotherms rely on absorbing environmental heat (e.g. reptiles), usually through the sun. Because of this, ectotherms suffer a much greater range in body temperature. This means that animals such as lizards will be slower and more sluggish when it is cold.

Being in a cold environment quickens the process of heat loss, robbing you of the precious heat you generate. A solution to this is shared bodily warmth. Also known as kleptothermy, this is a common thermoregulation strategy where a group of animals huddle together to share the heat generated by each other. This increases the efficiency of heat generation (thermogenesis) and the group as a whole can stay warmer for longer. This behaviour is commonly seen in communal animals such as mice, who huddle together even when they are newborns (newborns lose heat much quicker than adults due to the difference in weight to surface area ratio). Some ectotherms such as snakes and lizards also engage in kleptothermy, where by huddling together they increase their effective mass and reduce heat loss.

An interesting case of kleptothermy is seen in Canadian red-sided garter snakes, where the heat is not shared, but stolen. A male snake will sometimes emerge from hibernation and begin to produce fake pheromones to attract other males as if it were a female. Other males are fooled into thinking that the snake is female and approach it to mate. Through this strange process, the snake is able to steal the heat from its rival males and use the extra energy to mate with an actual female (or lose it to an even more cunning male snake).

Posted in Simple Pleasures of Life

Simple Pleasures of Life #5

Posted on by Jinavie

Having some experimental fun in the kitchen.

(Doing tomorrow’s tonight instead just because of my kitchen adventure)

Today I had my third go at baking (brownies again lol) because it’s my turn to bake for the team this week for O&G. See, I’ve always treated cooking like a bit of an…artistic science experiment. Baking more so because of the more precise measurements etc. In the process, I managed to:

  • Have 200g of butter explode in the microwave. Literally. The mug completely flipped out inside with a loud clatter and spilled all the butter…EVERYWHERE. Took a freaking hour to clean it all up… Luckily I had just enough butter left.
  • Guess (rightly) which setting to put the oven on. Seriously, those symbols might as well be hieroglyphs.
  • Improperly cool the brownie. I didn’t know I was supposed to take it straight out and put it on a cooling tray. Instead, I left it in the tin to “cool”, leading to the bottom being gooey and the top being cookie-hard OTL 
  • Creatively rebaked the brownie by flipping it over, re-molding the gooey brownie to fill the spaces left on the “bottom” (now top) of the brownie, then sticking in the oven with top heat.
  • Ultimately make a pretty tasty Oreo brownie! Not nearly as good as the one I made last time but this’ll do…

Anyway, baking is fun lol. But I think I’ll stick with cooking for now… And pancakes.

(Basically what would happen if I tried baking it)

Posted in Science & Nature

Silence Of The Trees

Posted on by Jinavie

A timeless philosophical question goes like this:

If a tree falls in a forest, does it make a sound?

This may sound absurd, but the question hangs on the definition of sound. Is sound the physical phenomenon of vibrating particles forming a soundwave, or is sound the sensory information that we perceive by converting said soundwave using our hearing system? If you accept the first definition, then yes, the falling of the tree will generate energy that pushes on the air particles around it, causing a soundwave that if someone were to hear it, would sound as a “thud”. But if you accept the second definition, then that tree would not have made a “sound” per se because no one was around to perceive the soundwave. Following this logic, a sound cannot exist without a recipient to hear it.

As simple as this may seem at face value, the riddle explores some deep philosophical and scientific issues.

The most obvious one has been discussed: the definition of sound. But then one must question what would happen if a tape recorder was running when the tree fell. Can a machine hear, even though it cannot “sense”? Is the sound we hear being played from the recorder the same as the sound that was originally made by the tree?

Following on from this thought, how do we know that the sound you hear is an accurate interpretation of the actual soundwave? It is common knowledge that the brain frequently modifies the senses to change what it sees and hears, as seen in various illusions. Furthermore, the brain can generate sensory information without any input, known as hallucinations. You assume that your hearing is flawless and accurate, but in your mind, it is almost impossible to know for sure that the sound you heard is “real”. Taking this further leads in to the massive debate of “what is real?” and “is reality real or is it a product of our mind?”.

A more fundamental question is this: if no one was around to hear the tree fall, does it matter if it made a sound? A pragmatic philosopher might say “no”, as whether the tree made a sound or not makes no difference to your life. However, a scientist may say “yes” as the tree did fall and a soundwave was generated. Whether a person was around to observe it is irrelevant as it does not change the fact that something real occurred. Then what effect does observation have on reality? How do we know that trees make the same sound when we are not around to hear it?

This is a crude dissection of the vast number of questions the riddle offers, but it shows how such a simple thought experiment can be an effective tool to engage your critical thinking. If you do not fully understand the philosophy discussed, at least you can take away the fact that you can use the excuse of “sound is only a perception, I did not hear you, therefore what you said did not happen” when someone tells you to do something.

Posted in Science & Nature

Thuder And Lightning

Posted on by Jinavie

The best or worst part (depending on your preference) about a dark and stormy night are the majestic flashes of lightning and booming thunder. Most people confuse the two terms, typically using “thunder” to describe both, but technically thunder is the sound produced by lightning, which is the flash of light. Lightning occurs when dense clouds become electrically charged due to the collision of water molecules. As charge builds up, the cloud becomes negatively charged. The negative charge becomes so intense that it begins to push electrons towards the surface of the Earth, creating a positive charge. Electricity always flows from a negative charge to a positive charge through a medium. The intensity of charges causes the air to become ionized (plasma), making it suddenly conductive and allowing the electricity to flow from the cloud to the ground. This is seen as a flash of intense light. As the electricity travels through this channel of air, it superheats the air and causes a massive expansion of air, much like an explosion. This creates an intense shockwave burst, producing a sound that we call thunder.

Lightning is a deadly force of nature. It clocks a peak voltage of somewhere between 30 million to billions of volts – far exceeding the electricity that can be generated by humans. When a lightning bolt strikes a human, it has a mortality rate of between 10~30%. The two effects of lightning on the human body is electrical shock and heat. As lightning flashes over the skin to reach the ground, it leaves a striking pattern known as Lichtenberg figures (see below), showing the path of the electrical breakdown. The intense electrical burst can cause loss of consciousness, arrhythmia or sudden cardiac arrest. The heat generated by the electricity can cause severe burns both externally and internally. It can literally fry internal organs causing permanent damage to the heart, lungs and brain. Neurological symptoms such as amnesia, confusion, sleep disturbance and chronic pain have also been reported. Strangely, there are also reported cases of lightning curing ailments such as blindness, deafness and baldness.

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Because lightning is light and thunder is sound, one can calculate how far away lightning struck using the time between the lightning flash and the sound of thunder. Sound travels at 340m/s, so by multiplying the number of seconds between the lightning and thunder by 340, you can deduce the distance in metres. For example, if you see a lightning strike and then hear thunder after 7 seconds, the lightning must have struck 340m x 7s = 2380m = 2.38km away.

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Posted in Science & Nature

Brazil Nut Effect

Posted on by Jinavie

Have you ever bought a bag of mixed nuts and noticed that Brazil nuts tend to be on the top of the pile? If you put nuts of various sizes in a bag and shake it, you will see that the larger nuts (such as Brazil nuts) will rise to the top slowly. This is strange as common sense dictates that heavier objects sink to the bottom. The strangest thing? No one knows exactly why this happens.

However, there are some persuasive theories. It has been suggested that the so-called Brazil nut effect is due to a phenomenon called granular convection. Convection is usually used to describe the movement of gases and liquids, where heated particles are more active and lighter, thus rising to the top. As the particles rise, they cool down and fall back to the bottom, creating a current. It seems to be that the same can be applied to solid particles, such as nuts. When the jar or bag of nuts is shaken, a vibrational force is applied. Nuts in the middle are pushed upwards by the vibration, with smaller particles filling the gap below. Once the nuts reach the top surface, the vibration pushes the nuts towards the side, where they are then pushed back to the bottom. However, larger nuts like Brazil nuts are too big to fit in this downward current so they stay on the top. 

The Brazil nut effect is not exclusive to Brazil nuts. A similar phenomenon can be seen with any large particles surrounded by smaller particles, like pebbles in sand or coffee beans in ground coffee. The theory of granular convection has still not been fully understood, with various factors such as nut density and air pressure seeming to play a role.