Category: Science & Nature

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

Around The World

Posted on by Jinavie

Imagine, if you will, a very long piece of ropethat loops around the Earth, fitting it tightly around the equator like a belt. If you wanted to raise this rope off the surface by one metre all around, how much more rope will you need?

The length of rope is the same as the circumference of the Earth which is 40,075km (24,901 miles). Ergo, it is easy to think that you would need kilometres of rope to extend it enough to float a metre off the Earth’s surface. However, in reality you need a mere 6.28m of extra rope to achieve this.

The reason is extremely simple, mathematically speaking. The circumference of any given circle is given by the equation 2πr, where r is the radius of the circle. Therefore, if you increase r by 1 unit (e.g. 1m), then the circumference increases by 2π x 1 = 2π = 6.28. No matter how large the circle may be, this rule does not change.

(This is a famous maths riddle, but here’s a much more interesting application of the concept in this What If? article. God I love that blog! http://what-if.xkcd.com/67/)

Posted in Science & Nature

Intelligent Life

Posted on by Jinavie

One of the great questions in science is “could intelligent life develop on planets other than Earth?”. Even the general populace has heard of programmes such as SETI (Search for Extraterrestrial Intelligent Life) and mathematical models such as the Drake equation that attempt to predict the possibility of extraterrestrial intelligent civilisations. But an equally intriguing question we seem to neglect is: “could intelligent life develop on Earth?”.

The definition of “intelligent life” is hugely varying, but nonetheless attempts have been made to compare our intelligence level to other animals. From the pool of research throughout the decades, the most “intelligent” non-human animals appear to be chimpanzees, bonobos, great apes, dolphins, elephants, certain parrots, ravens and rats. There is much research on the intelligence of cephalopods (e.g. the octopus) that has shown promise. If we were to shift the focus from individual intelligence, we could also consider “civilised” animals such as ants, as they are capable of building vast cities with intricate societies. All of this shows that intelligence is not exclusive to our species. We have simply walked down the path of evolution where the trait of ever-increasing intelligence, knowledge and wisdom have allowed us to adapt to and survive our environment. Ergo, it is fair to consider the possibility that other animals are walking a similar path that may lead to the making of a species with intelligence comparable to us.

However, this only raises the theoretical possibility of intelligent life. What is the realistic, practical possibility of intelligent life developing on Earth in the near future? Put another way, could intelligent life develop in the presence of a higher intelligent life (e.g. humans)? The road that brought us to throne of “the most intelligent species on Earth” was not an easy one. We are but one of many other hominid (human-like) species that evolution produced while tinkering with the concept. For example, there was a time when we (Homo sapiens) shared the Earth with other intelligent hominids such as the Neanderthals. The Neanderthals are commonly pictured as simple, knuckle-dragging apes but in reality they were just as intelligent as Homo sapiens during that time. They had a culture similar to our own, developed stone tools just as complex and even made cave paintings in a display of art. The reason why we are not breaking bad with Neanderthal neighbours now is that (according to one theory) we successfully outcompeted them, driving them to extinction (there is debate whether genocide and cannibalism was involved).

Evolutionarily speaking, it makes sense for an intelligent species to wipe out another species trying to compete with the ecological niche of intelligence. This has been discussed in many works of science fiction, such as Planet of the Apes where the emergence of intelligent apes leads to the destruction of human civilisation. Arthur C. Clarke discussed this as a side plot in his novel The Songs of Distant Earth. Upon discovering a species of sea scorpions that show signs of intelligence such as social hierarchy and metal collecting, the scientists suggest that they should allow it to develop, but ultimately the government decides to eradicate them as soon as they attempt to migrate to land.

Suffice to say, given our track record in history involving the countless times colonists wiped out other civilisations to serve their purpose, there is a good chance that any new intelligent life would immediately be removed by us if they had the misfortune of arising during our time.

image

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 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.

image

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.

image

Posted in Science & Nature

Lizard People

Posted on by Jinavie

What would the world be like if the dinosaurs had not gone extinct? In 1982, palaeontologist Dale Russell proposed a thought experiment regarding the possible evolutionary path of a species called Troodons. The Troodons were small, bird-like dinosaurs from the later periods of the reign of dinosaurs. They grew up to 2.4m in length and about 50kg in weight, standing on two slender hind legs. The most interesting feature of Troodons was their very large brain – six times larger than any other dinosaurs relative to their body weight. This would have most likely allowed the Troodons to be quite intelligent relative to other species, allowing it to utilise crude tools such as rolling a boulder off a cliff.

Russell believed that had the Cretaceous-Paleogene extinction event did not happen 65 million years ago (when a giant meteor struck Earth), the Troodons could have evolved in a path similar to humans, expanding their brain size and using intelligence as a tool of survival. Although its brain size was substantially lower than that of a human, he believes that through evolution, by the present its brain would be the size of a modern human’s. He also believed that evolution would have shaped the Troodons into a “dinosauroid” form, much closer to the shape of a human being. The Dinosauroid (nicknamed lizard people) would have had two fingers and a thumb, large eyes, no hair, internal genitalia (like reptiles), no breasts and a navel (the placenta is instrumental in giving birth to large-brained offspring). Their language would probably have sounded like a bird song.

Given the history of Homo sapiens and our competition and ultimate demise of similar sapient species, it is unclear whether we would have won the survival war against the Dinosauroids, or whether we would have even had the chance to evolve to our stage, as mammals rapidly filled the niche after dinosaurs were wiped out. There is much criticism of Russell’s thought experiment of the Dinosauroid being “too anthropomorphic” (too human-looking), but as suggested in the book K-PAX by Prot, perhaps the humanoid form is the most efficient natural design for an intelligent life form. Realistic or not, it is a fascinating projection of a world that could have been.

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.

Posted in Science & Nature

Natural Design

Posted on by Jinavie

We look around the world we live in and marvel in all its complexity and grandeur. But Mother Nature focusses on one thing when it comes to design: efficiency. That is to say, that nature strives to design things that will do the job best. For example, stars and planets are always round because a sphere is the most effective way to get all the mass as close to the planet’s centre of gravity as possible (a process known as isostatic adjustment). The wings of a bird have evolved to maximise the thrust generated at the least energy cost, while the sleek, teardrop body shape of fish allow for them to slip through water with minimal resistance. One of the best examples of nature coming up with the best design solution is beehives.

If you look closely at a beehive, you will find that it is made up of tiny hexagons. Each hexagon is a room that a bee can fit in and the walls are made from wax. The interesting thing about hexagons is that it has many properties that make it the ideal shape in construction.

Firstly, hexagons can fit together perfectly to tile a plane, meaning that bees can tile thousands of columns without wasting any space. The little columns even end in a unique pyramidal shape that allows them to tile up nicely with each other at the centre.

Secondly, a hexagon has 6 rotational symmetries and 6 reflection symmetries, making it very easy to tile as every bee will know what orientation to build their cell in using the side of any cell as a reference.

Lastly, in a hexagonal grid each line is as short as it can possibly be when tiling an area with the smallest number of hexagons. Therefore, bees can use much less wax when constructing hives, while achieving remarkable strength as hexagons gain lots of strength under compression. This design also allows for the maximum amount of honey stored in each cell.

Bees have mastered this architectural feat not through physics and mathematics, but through evolution – the driving force of nature. Over millions and millions of years, various types of bees will have experimented with square-celled hives or triangular-celled hives, but they could not survive as long as the hexagonal-celled bees because their hives were less efficient. This is exactly why nature is so good at coming up with the best solution to a problem. Because in nature, the best solution to the problem an environment offers is rewarded with survival.

Posted in Science & Nature

Cow Modelling

Posted on by Jinavie

There is a farmer who is unhappy with the milk production from his dairy farm. To rectify this, he writes to the local university asking for advice. A theoretical physicist responds to the request and visits the farm. He then takes many measurements such as the size of the cow and proceeds to do some calculations. After finishing all of this, he tells the farmer: “I have a solution, but it only works for spherical cows in a vacuum.”

The point of the joke is that in science, models are frequently used to simplify reality. Because there are infinite amounts of variables, it is impossible to predict anything unless the scenario is simplified through certain assumptions and removal of factors. For example, many physics principles make assumptions such as not accounting for air resistance. Occam’s razor states that if you shave away all the complex details, the simplest answer remains. But perhaps we oversimplify some things?