Tag: gravity

Posted in Science & Nature

Kessler Syndrome

Posted on by Jinavie

When we imagine catastrophes, we think of disasters involving mass destruction such as volcanic eruptions, tsunamis and nuclear war. But there are so many creative ways the future of humanity can go awry. For example, there exists a possibility of humanity losing the ability to launch anything into space for the foreseeable future.

This interesting hypothetical scenario was described by astrophysicist Donald J. Kessler in 1987. Earth is currently surrounded by many layers of orbiting satellites. Unfortunately, satellites eventually break down and its components can end up as space debris. Since there is nothing in the vacuum of space that will degrade them, space debris stay in an endless orbit around the Earth unless they fly low enough that they get caught by air resistance and burn up in the atmosphere.

Kessler proposed the following problem: what happens when debris collide and set off a chain reaction? Although we think of orbital objects as slow moving or even geostationary, orbital objects are travelling at extreme speeds – at least 8km/s (or 28,800km/hr). When two objects collide at such incredible speeds, there is a huge amount of energy released in the form of shrapnel.

If the orbit is dense enough with debris, it is theoretically possible that these shrapnel will hit another piece of debris and set off another reaction. If the chain reaction can sustain itself long enough, soon the entire orbit will be littered with high-speed shrapnel, obliterating any object trying to cross the orbital layer.

The implication of the Kessler syndrome is that it would essentially make it impossible for us to launch any new satellites or rockets into space. This would stop us from exploring the depths of space and dash any hopes of interstellar travel and space colonisation. Scientists are already working on policies to reduce further space debris and experiments on how to clear up debris. But without awareness of the issue, no change would happen.

With climate change becoming an increasingly pressing issue, it is ironic that our littering of space could potentially ruin our chances of escaping and finding a new home if the need should arise.

Posted in Science & Nature

Zero Gravity

Posted on by Jinavie

With the development of technology, we are now at a point in history where there is an abundance of video footages taken in space. Thanks to this, the general population can visualise the strange phenomenon that is the lack of gravity in space. We are able to see videos of objects and astronauts gently floating and even strange phenomena such as tears simply pooling around a person’s eyes rather than streaming down the face. Most of these scenes are from places such as the International Space Station which is in orbit around the Earth, as there has been no expeditions leaving Earth’s orbit since the last moon landing in 1972.

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However, the common misconception is that objects in space stations are in zero gravity conditions. Objects in orbit are still under the influence of Earth’s gravity, which is why they do not fling out into the depths of space. So why do astronauts in space stations look like they are not under the influence of gravity? The reason is that an object in orbit is travelling incredibly fast.

The International Space Station is about 420km above the surface of the Earth. Here, it experiences about 90% of Earth’s surface gravity, meaning that theoretically, it should fall straight back. However, the ISS is travelling at 8km/s (27600km/h) sideways at the same time – the orbital speed. Because of this, the ISS is falling back to Earth at the same rate as it is travelling tangentially away from Earth. This makes it travel at a blistering speed in a circle around the Earth.

Not only is the ISS free-falling around the Earth, but so is its contents. Therefore, the astronauts inside look like they are in zero gravity, but are in fact simply in free-fall, much like a skydiver. In this state, they experience no “weight” as the g-force becomes zero and the astronauts accelerate at the same rate as the ISS. Ergo, the astronauts are “weightless”, not in “zero gravity”. This condition can be simulated on Earth in the so-called “Vomit Comet” – an airplane designed to fly up and down along a certain path, to produce a weightless, free-fall when it falls.

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Posted in Science & Nature

Space Pen

Posted on by Jinavie

According to a popular legend, it is said that during the height of the Space Race, NASA was hard at work trying to develop a pen that could be used in space. The standard ball-point pen relies on gravity to pull the ink to towards the ball, allowing it to write. Obviously, this design does not work in space. NASA reportedly spent $1.5 million (some sources say $12 billion) and finally developed a space pen. This pen could write upside-down or in zero-gravity, on almost any surface and would work even at temperatures below freezing or over 300°C.
The Russians were faced with the same dilemma – they used a pencil.

As entertaining the story of overthinking Americans is, it is a complete urban myth. Both US and Russian astronauts used pencils in the early stages of the Space Race, but there were many flaws with pencils. Firstly, it was deemed unsafe to write important official documents using an erasable writing tool. Secondly, wood is combustible and fire is potentially disastrous on a space mission. Lastly and most importantly, pencil lead is made of graphite and broken tips and graphite dust are commonly released when using a pencil. Graphite is an extremely conductive material and if the dust were to go into an electrical circuit, it could easily cause a short-circuit and spark a fire.

To solve this solution, Paul C. Fisher – founder of Fisher Pen Co. – invested his own funds (not the US government’s) to create a pen that used pressure-loaded ink cartridges, making it perfect for zero-gravity use. NASA approved of the pen’s effectiveness and not long after, even Russia imported about a hundred of these space pens for their own use.

Posted in Science & Nature

Hammer And Feather

Posted on by Jinavie

What would happen if you dropped a 1kg ball and a 10kg ball at the same time from a high building? Most people would think that the 10kg ball would obviously fall faster and thus hit the ground faster, but the truth is they would fall at exactly the same time. The reason for this is that the force that accelerates a falling object is gravity, which on Earth is constant at 9.81ms-2. This means that no matter how heavy the object is, they will always accelerate by 9.81 metres per second per second. This was hypothesised by Galileo Galilei, who came up with the thought experiment of dropping two balls of different mass from the Leaning Tower of Pisa (there is debate as to whether he actually performed the experiment). The theory was later solidified by a certain Isaac Newton, who devised the laws of universal gravitation and the three laws of motion.

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However, if the two balls were dropped from an extremely high place, they may land at different times as mass affects the terminal velocity – when the force of gravity equals the force of drag caused by air resistance, leading to a constant velocity. A heavier object will keep accelerating to a greater velocity than a lighter object, which would have reached terminal velocity before the heavier object.

One place where this will not happen is in a vacuum where there is no drag force. To prove that the hypothesis that two objects of different masses will fall at the same time in the absence of air resistance, Commander David Scott of the Apollo 15 moon mission took a hammer and a feather with him. Once he landed on the moon, he dropped the hammer and feather in front of a live camera, showing that the two landed at exactly the same time. He thus proved that Galileo’s conclusion from two hundred years ago was in fact correct.

Posted in Science & Nature

Newton’s Apple

Posted on by Jinavie

Common belief is that Newton discovered gravity after an apple dropped on his head. Although there is no historical evidence to support this myth, it has become a popular story. There are two common responses to this story: the first is “Wow, Newton was a smart cookie” and the second is “Pfft, I could have discovered gravity without an apple, it is such an easy thing.”

The latter group of people are idiots. Newton did not “discover” gravity. Human beings have known that objects fall to the ground since the dawn of time and have utilised it in ways ranging from sports to killing other people by crushing them with giant rocks. Even animals know of the concept as seen by eagles dropping turtles on rocks to crack the shell. In fact, if you could not figure that out, then you would really be an idiot.

The reason why Newton is famous is not because he found that apples fall from trees, it is because he observed the phenomenon, noting that it was always perpendicular to the ground, which in combination with the knowledge that the Earth is round suggests that objects tend to fall towards the centre of the Earth. Again, Newton’s brilliance was not that he simply observed an apple falling, it was that he pondered it and spent years researching it until he discovered the way gravity behaves. He devised formulas to estimate how gravity functions, even applying it to predict how the moon orbits around the Earth. Thanks to Newton, we are able to model the world around us and send rockets to the moon without launching our astronauts in to the depth of space with no hope of recovery. 

Interestingly, physicists still do not know what causes gravity. There are many theories, such as particles called gravitrons attracting two objects to each other. Although the mathematics of two objects attracting each other has been accurately calculated, it is unknown what causes it. Only after you discover the truth behind how gravity functions can you say that “I could have discovered gravity in my sleep” (actually, even then you probably spent decades just trying to grasp the concept).

Before you criticise, know what you are criticising. 


Posted in History & Literature

Apple

Posted on by Jinavie

Apples are strewn throughout history and mythology, acting as a key component of human societies. Its symbolism ranges from the sin of Adam and Eve to the love of Aphrodite. Let us look at some apples that have made a significant impact in the world – real or mythical.

Apple of Temptation: According to the bible, Eve is tempted by the snake to take the forbidden fruit from the Tree of Knowledge. By taking from the tree and eating this fruit (then sharing it with Adam), the two are banished from the Garden of Eden and humanity is cursed to live in the harsh world and for women to suffer the pain of childbirth. Although the bible never defines the forbidden fruit as an apple, artistic depictions during the Renaissance has solidified the idea. The eponymous Adam’s apple (the lump on men’s necks) is said to be a piece of the apple being stuck in Adam’s throat.

Apple of Discord: According to Greek mythology, Eris (goddess of discord) threw a golden apple into a wedding after not being invited to it. The apple was inscribed with the message: “For the fairest one” and Hera, Athena and Aphrodite all claimed the apple was for them. Eventually, the judgement was delegated to Paris, prince of Troy. Each goddess bribed him with power, strength and love respectively but Paris eventually chose Aphrodite and in return, received the most beautiful woman in the world – Helen of Sparta. This sparked the great Trojan War, resulting in the destruction of Troy by the Greek alliance.

Apple of Love: Atalanta (Greek mythology) was a beautiful woman who had sworn virginity to the goddess Artemis. To avoid marriage, she challenged suitors to a footrace and only the winner would take her hand in marriage (the rest were killed). A man named Hippomenes went to Aphrodite’s temple to seek advice and was given three golden apples. He used the apples to distract Atalanta during the race by tossing it near her. This allowed him to win the race and ultimately took Atalanta’s hand in marriage. This story also shows how the ancient Greeks saw apples as a symbol of love, as evidenced by the gesture of one throwing an apple to the person they are in love with. Catching the apple was accepted as a sign of reciprocity.

Apple of Challenge: One of Hercules’ twelve challenges was to take the Golden Apples of Hesperides, protected by Ladon, a dragon with a hundred heads. Hercules bargained with Atlas to hold the Earth while he retrieved it. Atlas tried to walk away free from his damned task, but Hercules tricked him by asking to hold the Earth while he shifted his cloak.

Apple of Death: In the fairy tale, Snow White, the evil queen uses a poisonous apple to murder Snow White. The symbolism of the apple is similar to the biblical story mentioned above. Despite the dwarves warning her about stranger danger, Snow White takes the gift of a stranger without enough caution and suffers the consequences. However, she is resurrected by the kiss of the prince. Perhaps Aphrodite’s apple of love counters the evil apple of death and sin.

Apple of Revolution: A famous Swiss folklore describes how William Tell had to shoot an apple from his son’s head with his crossbow as punishment for not submitting to the occupying Austrians’ leader, Gessler. Being an expert marksman, he successfully hit his target instead of killing his son. When he was questioned why he drew two bolts from his quiver, Tell replied that he was aiming to shoot Gessler if he accidentally killed his son. This infuriated Gessler, who arrested William Tell. However, Tell escaped and went on to lead the revolution against the oppressors, aiding in the liberation of Switzerland (according to the legend).

Apple of Philosophy: There is a record of a young Martin Luther (who founded the protestant church) writing in his diary: “Even if I knew that tomorrow the world would go to pieces, I would still plant my apple tree”. The philosophy behind this saying is not that gardening is important. Here, Luther is saying that we should live every day as if it is the last day. Live without regrets. Besides, would we not look silly if the world did not end and we had wasted a day panicking and doing absolutely nothing productive?

Apple of Knowledge: The story of how Isaac Newton devised the theory of gravity after being hit on the head with an apple is a famous story. Although the “hitting on the head” part is dubious, evidence suggests that he used apples falling from a tree as an example of how gravity works. Although the concept of gravity was already established, Newton focussed on how apples always fell perpendicular to the ground and deduced that objects have a gravitational pull on other objects (as the Earth pulls the apple and vice versa). He extrapolated from the apple to discover how Earth’s gravitational field controls the orbit of the Moon. Thus, it can be said that apples played a “crucial” role in the advancement of modern physics (although Newton probably did not need the apples for his theory).

Apple of Innovation: In 1976, Steve Jobs co-founded Apple Inc. to develop the first personal computer. The company would go on to revolutionise mainstream digital technology by coming up with innovative products such as the iPod. Steve Jobs was the face of this new wave of innovation; with his bold outlook on the future and powerful leadership he made Apple Inc. one of the most successful companies in the 21st century. Jobs successfully popularised many pieces of technology, such as personal computers, portable music players and tablet PCs. Interestingly, he came up with the logo and name of the company after seeing a cartoon of Newton and his apple. Perhaps Jobs was seeking to create a company that would be one of the many “apples” that were turning points in history.

Posted in Science & Nature

Buttered Cat Paradox

Posted on by Jinavie

Cats always fall on their feet. Buttered toast always seems to fall buttered side down. So what would happen if we tied a buttered toast on a cat’s back and then dropped the cat? Would the cat land on its feet or would the toast land on its buttered side?
Or would we achieve perpetual motion and anti-gravity simultaneously as they cancel each other and never touch the ground?

Although the paradox is obviously a humorous thought experiment, there is some truth to the separate adages. 
Cats have a natural righting reflex that allows them to twist their upper body so that they land on their feet. This gracious manoeuvre is developed as a kitten and actually involves quite complex physics where the cat is able to turn around without changing their net angular momentum. Since cats have a small body and very light body weight, their terminal velocity (100km/h compared to a human’s 210km/h) when falling is much less and allows them to absorb the shock easily when landing. Furthermore, when falling cats naturally spread their limbs out to slow their fall as much as possible. All these factors let a cat land safely on its feet even if dropped from a high place. Ironically, the lower they are dropped from, the more likely that the cat would fall on its back.

The other side of the paradox is slightly more complicated. The adage that toast falls buttered side first is actually an example of how if something bad can happen, it will happen. However, physicists have discovered that toast is more likely to fall on its buttered side.
When toast falls off a plate, it is highly likely to tip as it hits the edge. This causes it to rotate as it begins to fall. There are two explanations on why the buttered side is more likely to be facing down. Firstly, butter adds weight to one side and heavier objects fall faster in the face of gravity. Secondly, using experimental data it has been found that toast only rotates about 180 degrees by the time it falls the height of the table or person from where it was dropped from. 

Despite it only being a tongue-in-cheek thought, one can only wonder how many scientists have made some toast, buttered it, tied it to a cat and dropped the cat off a ladder.

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Posted in Science & Nature

Dimensions: To Infinity And Beyond

Posted on by Jinavie

So far we have covered 6 dimensions: point, length, width, depth, time, alternate universe and travelling between possible futures being the key feature of each. Hopefully, you as the reader have caught on to the pattern of dimensions so far: point (0D) -> line (1D) -> branch (2D) -> fold/point (3D) -> line (4D) -> branch (5D) -> fold (6D)… This pattern of point/line/branch/fold continues past the 6th dimension. Therefore, the 6th dimension acts quite similarly to our 3D world in that we can assume it to be a point.
The 3rd dimension was a point in time. So what could the 6th dimension be a point of? The answer is infinity.

It was mentioned that the 5th dimension carries all of the possible alternate timelines that are created from a certain point. In the 6th dimension, these branches fold up to meet so that we can travel freely between every point. Therefore, the 6th dimension is a point that contains every possible timeline – where anything that can happen in the universe exists. This is infinity.

But by definition, infinity encompasses everything as there is no “end”. Then has our journey ended? In a fascinating turn of events, it turns out that we can not only ascend to the 7th dimension, but there are still 3 more dimensions to travel through.
By now we know that as the 6th dimension was a “fold/point” dimension, the 7th dimension must be a line connecting different 6D points (infinity). How can there be more than one infinity? Actually, infinity is only as great as the initial conditions from whence it was born – the Big Bang. In terms of universes, these initial conditions are the laws of physics such as gravity, the speed of light and hundreds of other constants. For example, gravity is 9.81ms-² in our universe. But if this value was off by even 0.0001, our entire universe would be completely different. Ergo, our universe and all the timelines that have and will form depend on the Big Bang. This also means that there can be many other “infinities” with different laws of physics. The line that these infinities lie on is the 7th dimension.

A good analogy for this is genetics. People’s lives have different outcomes depending on their choice, actions and random chance, but they cannot escape their pre-programmed genes. For example, it is not expected that a boy will (naturally) grow into a woman or sprout wings and fly. But if they were born with two X chromosomes or born with the DNA of a bird, this life would be possible.

Now let us follow the basic pattern to move to the 8th dimension. Here, the 7D line branches to meet yet another point of infinity (6D). And yet again, we can bend these branches through the 9th dimension to jump from one universe to another.

Lastly, we can take all of these branches and folds that encompass all possible timelines and all possible universes and draw it as a single point in the 10th dimension. This one point is the relative and absolute “everything”.

But what now? It is impossible to reach past the point of “everything possible”. This means that we cannot jump up another dimension as no other 10D point exists to be connected to. Ergo, the highest possible dimension is 10D and this is the basis of string theory. The 10th dimension is where the so-called superstring vibrates to form the subatomic particles that are building blocks of every matter in our universe.

As mind-boggling a journey it was, if you were able to follow through from the start, we have travelled from a single point that occupies no space to another point that encompasses all things possible in our universe in all possible timelines. We have zoomed out to the point that there is no longer a box to “think outside of”.

Can one ever reach that point where one knows everything that was, is and will be? To know every piece of knowledge that is the absolute yet relative truth? Although we cannot physically jump through dimensions, our minds can keep rising up to raise our level of understanding and enlightenment higher and higher. As we only live in the 3rd dimension, we have no less than 7 more dimensions to explore and understand. Only when we have reached the 10th dimension can we say that everything possible has been discovered.

Until then, anything is possible.

(This post is part of a series exploring the concepts of dimensions. Read all of them here: https://jineralknowledge.com/tag/dimensions/?order=asc)

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Posted in Science & Nature

Murphy’s Law

Posted on by Jinavie

In 1947, an aerospace engineer named Edward A. Murphy Jr was involved in high-speed rocket sled experiments led by the US Air Force. The aim of the experiment was to research the effect of sudden deceleration on the human body so to improve the safety of jet fighter pilots. To study this, a flight surgeon named Dr John Stapp devised a “sled” attached to a rocket that could be used on a long track. The rocket would propel the sled to a massive speed and brakes would induce as sudden deceleration. However, they found that the machines that were used to measure the G-force (force of deceleration relative to the force of gravity) were unreliable. Murphy proposed that they use electronic strain gauges attached to the harness of the test subject to measure the G-force, something he learned while working with centrifuges.

The idea was great but there was one problem: the gear kept failing, showing no reading whatsoever. Murphy soon found that the sensors were attached correctly but were wired backwards. This simple mistake frustrated Murphy, who blamed the incompetency of his assistant, stating that “if that guy has any way of making a mistake, he will.” This became the famous Murphy’s law, now simplified to “Anything that can go wrong will go wrong”.

Murphy’s law actually played a fundamental role in defensive design, where the worst-case scenario is always assumed and prepared for. Thanks to this system, the rocket sled experiment was successful and in 1954 Dr Stapp became the fastest man in the world – travelling at a speed of 1011km per hour and decelerating at a force of 46G (it was hypothesised that a human being could not survive past 18G). Not only did he survive (albeit with broken limbs, ribs, hernias, detached retina and temporary blindness), Dr Stapp went to build bigger rockets to further test the limits of the human body.

Interestingly, there’s another side to the Murphy’s law involving psychology. People suffer from a fallacy called appeal to probability, where they believe that because there is a possibility of something can happen, it will happen. The brain is surprisingly inefficient in dealing with probabilities and has a tendency to ignore that there is a relatively miniscule possibility and instead focuses on the absolute fact that there “is” a probability. This is the best explanation for why people are compelled to buy lottery tickets and why every student believes they will grow up to be rich and successful. 

Posted in Science & Nature

Bat

Posted on by Jinavie

The most famous characteristics of a bat is its behaviour of hanging upside down. This strange behaviour actually greatly benefits a bat’s survival.  Because a bat’s wing is structurally different to a bird’s, it cannot generate enough flight to lift a bat off the ground directly. Therefore, bats leap off a high location to fly, so hanging from a high place allows them to fly off at any given moment. Also, living in a high place provides protection from predators.

A bat’s anatomy has heavily adapted to accommodate this behaviour. Thanks to its unique anatomical structure, a bat expends no energy while hanging. This is because they have talons that are designed to clench naturally when pulled by gravity, as the tendons tense. Thus, when hanging upside down, a bat can rest peacefully, and can even sleep in that posture as it requires no muscle action (all muscles relax in REM sleep).

As it is the norm to live upside down, a bat does everything in that manner. As stated above, a bat sleeps upside down, eats upside down, mate upside down, and even stay like that after death. There is only one time a bat stands upright: when it excretes waste. Even behaviour cannot overcome the power of gravity.