Tag: physics

Posted in Science & Nature

Nuclear Explosion

Posted on by Jinavie

Nuclear weapons are quite possibly the most dangerous weapons mankind has ever developed. Through the use of nuclear fission, atoms are split to release the massive amounts of energy contained within, causing a gargantuan explosion. When a typical nuclear bomb detonates, energy is released in various forms: blast energy (40~50%), heat (30~50%), radiation (5%) and fallout (5~10%). The distribution of the energy varies according to the type of bomb (e.g. neutron bombs produce significantly more radiation than heat and blast energy).

The initial damage that follows a nuclear explosion is from the blast energy, much like a conventional weapon. The sheer amount of kinetic energy creates a shockwave that pulverises everything in its path, travelling at speeds over 1000km/h. In addition, the heat from the explosion, over ten million degrees celsius at one point, causes vaporisation of all matter within a certain radius, causing a massive release of gases, fuelling the shockwave from the expansion. In the case of the bomb that destroyed Hiroshima, all structures within 1.6km were vaporised and those within a 3.2km radius suffered moderate to severe damage. A modern nuclear weapon is at least tens of times more destructive and will affect a significantly larger area.

At the same time, thermal radiation spreads out in all directions much like sunlight. Thermal radiation travels far further than shockwaves and can cause severe burns and eye injuries (flash blindness) to people in the vicinity (if they are close enough, they will spontaneously combust or melt). Near ground zero (point of explosion), a firestorm may erupt from the sheer amount of heat energy, as observed as a fireball. 

Next comes the indirect effects.
Ionising radiation is produced when atoms are split and these have detrimental effects on living organisms. Not only are they responsible for mutations in the genome, leading to deformed offspring, sterility and cancer, but if there is sufficient radiation, a person will immediately die from acute radiation poisoning.
The same radiation, especially gamma rays, creates what is called an electromagnetic pulse (EMP). EMP is caught by metal objects and induces a high voltage surge, destroying unshielded electronic devices. Sometimes, nuclear bombs are detonated at very high altitudes so that only the EMP affects the ground, damaging enemy communications and destroying entire power grids.
Lastly, radioactive material rains from the sky for long periods of time, also known as fallout. Fallout causes continuous radiation damage in affected areas.

A nuclear bomb is truly a weapon of mass destruction as it utilises various forms of destruction to devastate all life forms within an area spanning several kilometres, even killing over the course of time in the form of radiation.

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 Science & Nature

Fire

Posted on by Jinavie

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 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

Dimensions: Time Warp

Posted on by Jinavie

The first three dimensions covered the three variables that determine space: length, width and depth. Then what could the fourth dimension possibly add? The answer is duration. The third dimension effectively becomes a point and the 4th dimension connects different 3D points to form a line that we refer to as time. For example, the “you” at this exact time is different to the “you” in five years time. These two “you”s are different (3D) points that lie on a 4D line (more specifically, your life). This is exactly the same principle as the 0th dimension being points in a 1D line, except three dimensions higher.

As a “moment” in 3D space is just a point on a 4D line, travelling from one point in time to another (i.e. time-travelling) would be as easy as walking along a straight line for a four-dimensional being. This concept is mind-blowing for us as we cannot fathom the concept of manipulating time. We are unable to see time as a dimension as we exist in a lower dimension. Every single moment in our lives is a brick that paves the road called time, meaning that we can only see each individual brick and not the overall picture. This is exactly the same as how a Flatlander could not understand the concept of depth and how we can be above them.

Although we see time as linear and straight, we are under the same illusion as the ant walking down the Mobius strip. Time is actually twisting and turning in the fifth dimension, creating multiple timelines that branch out like a tree of possibilities. These branches are influenced by our own choice, chance and the actions of others.
In other words, if a man proposes to girl A then he will go down the branch where he marries girl A. However, if he chose not to propose, he would end up marrying a different girl (or not at all). Therefore, he has entered a different branch than the girl A branch.
Now, if the man wanted to go from a timeline where he married girl A to another timeline where he married girl B, what could he do?

One method would be if he bent the 4th dimension (time) on itself through the 5th dimension to travel back in time to when he met the girl and not ask her number. This is exactly like folding a 1D line into a 2D circle to make the end point meet the starting point. However, to marry girl B he would have to make the right sequence of choices that lead to him marrying girl B (much like a role-playing game). This is the long-way round that would be too time-consuming and complex.

A simpler approach would be if he folded the 5th dimension through the sixth dimension and jump from the ending of timeline A to timeline B. This would be like the finger-lifting analogy we have been using time after time. If we pretend that the 5th dimension was a piece of paper, then we could fold it into a 6D cylinder so that the two edges meet. Now we are able to jump from one ending to another effortlessly, just as we did in the 2nd dimension.

It is easy to confuse the 5th and 6th dimension as they both deal with “alternate realitites”. Here is one way to differentiate the two: 5D space is like a 2D space for time – a flat plane where different timelines cross each other. Therefore, it can contain all of the possible outcomes from an initial condition – that depends on an action, choice or chance – such as your conception (visualise a dot on a piece of paper with many lines radiating out from it).
If we were to put a dot on a piece of paper above the first piece of paper (in the 3D space for time), we have entered a universe where there is a completely different starting point (before your conception), such as dinosaurs not existing. This means that the line called “you” may not even exist, and the two pieces of paper would never meet. The only way to jump from one piece of paper (5D) to the other would be through the 6th dimension.
Therefore, by jumping up a dimension, we gain a degree of freedom where we can move in yet another direction. This is seen between every dimension, such as 2D versus 3D. The 6th dimension merely lets us travel between different sheets of 5D paper.

So somehow we have reached the 6th dimension where one can not only time-travel, but jump from one alternate reality to another. Shall we venture further into the seventh dimension – infinity – and beyond?

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

(Stick figures from xkcd)

Posted in Science & Nature

Dimensions: Flatland

Posted on by Jinavie

As we live in a three-dimensional world, it is difficult to imagine that there are higher dimensions. To illustrate this, the thought experiment of the hypothetical “Flatland” can be considered. Let us assume that there is a two-dimensional world called Flatland. Here, the concept of depth does not exist. Only forwards, backwards, left and right exist; there is no up and down. Everything that happens here would look like it was drawn on paper.

Now let us interact with Flatworld. If we were to touch Flatworld with our finger, it would be like poking your finger through a newspaper. The inhabitants of Flatworld would see a circle suddenly appear out of nowhere that grows larger and larger. A person would appear as if they were being seen through a CT scanner – in sections. The concept that things can be above or below would sound crazy to a Flatlander, even though to us it appears as a simple concept.

Let us take an ant walking along a piece of paper as an example of a “2D object”. If the ant wishes to go from one edge of the paper to the opposite edge, it must walk along the 2D plane. However, with our 3D powers, we can fold the paper into a cylinder; now the ant can walk to the other point in an instant (across the fold). To another ant on the other side, the ant would look as if it teleported and suddenly appeared out of nowhere.

In another experiment, we make a Mobius strip (a ribbon is twisted once then its two sides are joined) and make an ant walk along it. Although the ant would think that it was walking in a straight line along a two-dimensional surface, it would have walked on both sides of the strip – a three-dimensional concept. If the Mobius strip concept is confusing, think of a garden hose instead: an ant walking along a straight garden hose is walking in: 1D (straight line), 2D (hose is actually a flat surface) and 3D (the ant can walk in a corkscrew pattern along the hose).

If we were to tell that ant that it had just travelled in a higher dimension, that ant would either scoff at us or be genuinely terrified of the experience. To it, we (or the giant pink circle that it sees our finger as) would look like some omnipotent being that can see everything going on in its world and teleport from one place to another. And although the concept of depth would initially intimidate the ant, it would bring the level of the ant’s understanding of the world up one dimension. For if we see what we only know, then how can anyone see anything new? The only way to truly learn and understand new things would be to jump out of the box and see everything from the outside – just like an ant seeing the piece of paper it was on from a higher ground.

Although we may laugh at the foolishness of the Flatlanders (and the ant), to a being of the 4th dimension, we would appear just as stupid and naive. By applying what we learned from the world of Flatland to our three-dimensional world, we can expand our horizon of knowledge and understand what the fourth-dimension is.

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

Posted in Science & Nature

Dimensions: Exploring The Dimensions

Posted on by Jinavie

In the 21st century, films and television have evolved to show 3D images. However, most people only have a crude understanding of what dimensions actually mean. This is a guide that will explore the incredible journey from a zero-dimensional point to a tenth-dimensional point and all the wonderful lines and folds that lie in between.

A point in space has no area – this is the zeroth dimension.
When two points are connected, it forms a line – the first dimension. This line allows one to travel from one 0D point to another, introducing the concept of length.
Another line is drawn branching off this line in a different direction – we have entered the second dimension. Now we have the concept of width.
By adding another concept – depth – we ascend to the third dimension. Now it is possible to go from one point on a 2D surface to another as we have “folded” a branch in the second dimension to meet the other branch. A simple explanation would be lifting your finger off one point and placing it on another point.

To simplify our journey to the third dimension we have:

  • Assumed a “point” in space as a dot (.)(0D)
  • “Joined” two dots to form a line (|)(1D)
  • “Branched” the line to create two ends (Y)(2D)
  • “Folded” the branches together to make the two ends meet (P)(3D)

These four concepts of point, joining, branching and folding are crucial in understanding how the different dimensions interact.

An interesting thought regarding the concept of dimensions is perception. How would inhabitants of each dimension view different dimensions? This is easy for lower dimensions (2D and below) because we can see them as a dot, line, square and cube (our dimension). Ergo, we can easily understand all the concepts of the lower dimensions (e.g. width). However, the opposite would not be possible (e.g. a 2D being trying to understand depth) as the concept does not exist in their dimension.

To further explore this thought, we must explore the world of Flatland.

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

Posted in Science & Nature

Stone Skipping

Posted on by Jinavie

Stone skipping refers to the act of throwing a flat stone on a calm body of water to make it skim the surface and seemingly bounce. However, this is a technique that is hard to master and usually results in the stone simply sinking. Thus, a paper researched how one can improve their stone skipping skills.

According to the study, a stone that is 5cm in diameter, 2cm thick and about 100g in weight is ideal. But choosing your stone is only the first step.
This stone must enter the water at 20 degrees at a speed of over 90km/h to make sure the stone will skim. Furthermore, the stone needs to be lifted up about 20 degrees against the water.
Lastly, the stone needs to be spinning with enough force to drive it forwards while keeping it off the surface of the water. This is known as the gyroscope effect (the same reason why a top does not fall when spinning).

However, it is difficult calculating and throwing the perfect angle and speed unless you are a machine. Ergo, the only effective way to master the skill is through practice and effort.
A handy advice is to throw the stone as fast as possible from a low position, letting go of the stone just below your knee height-wise.

Posted in Science & Nature

Titanic

Posted on by Jinavie

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…