Tag: physics

Posted in Science & Nature

The Titanic Door Debacle

Posted on by Jinavie

One of the most famous arguments in popular culture history is why at the end of the movie Titanic, Jack had to die when it clearly looked like there was enough space for both him and Rose to lie on the floating door.

Since the movie’s release in 1997, countless fans have lamented how the birds-eye view shows that both people could have laid side by side to fit on the door.

But alas, science is an unforgiving mistress and it has since been shown that it would have been physically impossible for the two lovers to survive together on that makeshift raft (which was a wooden panel, not a door).

The film actually shows Jack trying to get on to the panel, when it tilts and starts to submerge, nearly flicking Rose off. Jack realises that the panel would not support both of them and chooses to only keep his upper body on it, while fending off other survivors trying to latch on. Unfortunately, this is not enough to keep him alive as he quickly succumbs to hypothermia and sinks to the bottom of the ocean.

The important question is not whether the two would fit on the panel, but whether the panel is buoyant enough to support both of them.

Buoyancy is the force that makes things float in liquids. It depends on the volume of the floating object and the density of the liquid it floats in. If buoyancy is greater than the pull of gravity, the object floats.

Now, let us calculate how much buoyancy we would need to keep the panel, Rose and Jack afloat.

For the two to survive, no more than the door itself can be submerged, keeping the bodies above water level. Therefore, the volume of the submerged object is the volume of the raft. Estimating from stills from the film and Kate Winslet’s height, we can calculate the raft as being roughly 1.85m x 0.95m x 0.15m, or 0.264m³.

Ergo, the buoyancy of the panel would be Volume x Density of ice cold salt water x force of gravity = 0.264m³ x 1000kg/m³ x 9.8m/s² = 2587N (Newtons). If more than 2587N of weight is placed on top (including the panel itself), it would sink.

At the time of the production of Titanic, the estimated weight of Kate Winslet and Leonardo DiCaprio were around 549N and 686N respectively (note that in physics, weight is mass times the acceleration of gravity, measured in Newtons).

Subtracting these values from 2587 leaves us with 1352N free for the panel. Since we know the volume of the panel, as long as we know what wood it was made out of, we can find the density and calculate the final weight.

Three types of wood were commonly used on the Titanic: teak, oak and pine. The densities of these woods are 980kg/m³, 770kg/m³ and 420kg/m³ respectively, meaning that the door would be 2535N if it was made of teak, 1992N for oak and 1087N for pine.

Therefore, the maths show that for the two to have a snowball’s chance in hell of surviving together on the panel, it had to be made of pine. Teak and oak would have been too heavy.

This is where the final key becomes relevant: the wooden panel was likely made of oak.

The Maritime Museum of the Atlantic in Halifax, Nova Scotia, holds the largest piece of debris from the actual wreckage of RMS Titanic. If you look at this wooden panel (from above a doorframe), it looks remarkably similar to the wooden panel that Rose survives on. In fact, a replica of this debris was used for the filming of the film. The material of the actual wooden panel? Oak.

If the panel was made out of oak, it could only hold Rose, as 1992 + 549 = 2541N, which is just enough for Rose to stay afloat above the water level.

And there you have it. Not even the power of love can overcome the cold-hearted, brutal law of the universe that is science.

Posted in Science & Nature

Shooting Star

Posted on by Jinavie

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

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

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

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

Posted in Science & Nature

Antimatter

Posted on by Jinavie

Nature is surprisingly balanced. For every action, there is an equal and opposite reaction (Newton’s Third Law of Motion). Energy can change forms in an isolated system, but cannot be created or destroyed as the total energy must remain constant (Law of Conservation of Energy). Similarly, matter is balanced by the existence of antimatter.

Antimatter is a substance that is the polar opposite of matter. For example, instead of positively charged protons and negatively charged electrons, anti-protons are negative and anti-electrons (or positrons) are positive. Much like matter, antimatter particles can interact with each other to form more complex particles, such as an anti-atom, meaning that it is conceivable that an entire world could be made out of antimatter.

When antimatter and matter collide with each other, they annihilate. Much like the equation 1 + -1 = 0, the two opposites cancel each other out. Conversely, to create matter out of nothing, you must create an equal amount of antimatter to balance it out. Strangely though, physicists have noted that there is a great imbalance between the two in the observable universe. There seems to be far more matter than antimatter, which does not make sense. The question of why this imbalance exists is one of the biggest unsolved mysteries in physics.

An interesting lesson we can take away from antimatter is the concept that to create something out of nothing, you must balance it out with “anti-something”. If you borrow money from the bank, you may have $1000 now, but you have also created a -$1000 debt. The total balance is still 0.

The same concept can be applied to happiness. If something makes you happy, then the possibility exists that the same thing can cause you an equal amount of grief. Let’s say you find a fulfilling relationship with a significant other who brings you extreme joy. This is balanced by the extreme grief that will be brought to you if the relationship is strained or ends abruptly. Ironically, the pursuit of happiness creates more room for potential misery, as grief comes from the loss of something we care about.

So what does this imply? Does it mean that we should avoid falling in love or caring about anything, because it will only hurt us in the end? Should we even bother trying to live a happy life if it is cancelled out by all the sadness that it can bring along the way? Of course, these are silly thoughts. How dull life would be if we did not have any ups or downs.

Instead, the lesson here is that we should be mindful that happiness is not free. Grief is the price we pay so that we can experience the wonderful moments of joy, love and connection that life can give us only if we reach out. If you avoided connecting with someone or taking a leap of faith due to fear of failure or loss, then your life would be empty. This philosophy allows us to be grateful for the joyful moments, while helping us endure grief as we know that is the price we must pay for true happiness.

You can’t let fear steal your funk. To quote Alfred Lord Tennyson: 

“‘Tis better to have loved and lost than never to have loved at all.”

Posted in Science & Nature

Car Keys

Posted on by Jinavie

There are times when you park your car, start walking away and you remember that you forgot to lock the doors. You click your remote car keys but you are already just far enough that the signal does not reach your car. Fortunately, there is a lazy way to extend your car remote’s range.

If your hold your remote against your head (such as next to your chin or your temple), you will find that suddenly, the remote works from a longer distance like magic. How can this be?

There are two explanations that factor in.

The first is very simple: height. The higher you hold your remote, the less barrier there is between you and the car, making the signal more likely to reach it. But this cannot be the only answer as the trick works when there is nothing between you and the car.

The second explanation is more technical. When you press the key to your body and click it, the electromagnetic waves that comprise the signal can cross past your clothes and skin into your body, which is mostly composed of water. The water acts as a capacitor as the signal starts to “charge” you, all the while the signal is being rapidly bounced back and forth between the remote and you. In essence, your body acts as a giant aerial that amplifies the signal, almost doubling the range of the remote.

Arthur C. Clarke once wrote: “Any sufficiently advanced technology is indistinguishable from magic”.
But even the simplest scientific principles can seem like magic until we bother looking under the hood.

Posted in Philosophy

Changing The Past

Posted on by Jinavie

If time travel was possible and you could go back in time to change one thing in the past, what would you change?
Would you try to change the world by attempting to kill Hitler before World War 2 starts? Would you buy stock of a company you know is doing extremely well in the present? Would you take a leap of faith that you never did, such as asking out someone you didn’t have the courage to, or moving to a city that you always wanted to live in?

If we ignored the numerous hypothetical troubles that come with time travel, such as the grandfather paradox and chaos theory, the possibilities seem endless. This is because hindsight is 20/20 and we have a tendency to obsess over roads not taken and missed opportunities. Even though we cannot change the past, we lament how if we had the choice, we’d make so many changes to make our present and future better.

Now ask yourself this question: if you from the future could travel back in time to now, what changes do you think they’d want to try to make? The thing with time is that it marches on linearly, making every moment a past of the future. A major difference in this scenario is that unlike the first scenario, we actually have the power to change in the present and the future.

So whenever you catch yourself regretting how life would be different if you had made different choices in the past, change your frame of mind. Instead, consider what changes you could make now to make your future self have less regrets. Maybe it is treating yourself (within reasonable limits), or finally taking that trip you always dreamed of, or taking a chance on something you are unsure or anxious about, or keeping resolutions on living a healthy, better life.

Although physics (currently) dictates that time travel is impossible, our minds have the power to travel in time virtually from the future to now, letting us make choices and take actions so we can live with less regrets.

(Image from the movie About Time)

Posted in Philosophy

Quantum Immortality

Posted on by Jinavie

The famous Schrödinger’s cat thought experiment illustrates the Copenhagen interpretation of quantum physics. Quantum physics is an extremely complicated field of study, but the gist of the Copenhagen interpretation is that a probability remains in a superposition – that is a state where many possibilities exist at the same time – until it is observed, when it collapses into a certain state.

For example, imagine a cat that is locked in a box sealed with a vial of poison, that is set to break open only 50% of the time. Until the box is opened, we do not know if the cat has been killed by poison or not. Therefore, the cat can be said to be both alive and dead at the same time (Erwin Schrödinger initially devised the experiment to mock the Copenhagen interpretation).

There is a fascinating theory that takes this strange thought experiment one step further. Another interpretation of quantum physics is the Everett many-worlds interpretation. This explains that instead of the wavefunction collapsing (i.e. producing a single result such as alive or dead) on observation, two parallel universes are created instead: one universe where the cat died and another universe where the cat is still alive. Essentially, it states there are infinite universes containing every permutation of possibilities that can exist and that whenever a probability is observed, we enter a specific universe.

This is a very confusing concept to grasp, so let us return to the cat in the box. According to the Copenhagen interpretation, the cat has a 50% chance of surviving the experiment the first time. From then on, the chance of the cat being dead grows exponentially with every experiment. However, according to the many-worlds interpretation, no matter how many experiments we perform, there always will be a universe where the cat miraculously survived each one. From the cat’s perspective, it would not know of the universe if it had died. Therefore, the only universe where the cat is able to tell this story to its friends at the end of the day is one where it survives every single experiment

Now let us apply that to our own lives. Imagine that you are crossing the road and a bus is about to hit you. If there is even a 1% chance you might survive this event, your quantum self will move to a universe where it is possible (otherwise you would be dead and your consciousness ceases to exist). By extrapolation, you can never really die as a version of you will forever live on, beating improbable odds until a point where there are literally no possible universes you could be alive.

Quantum immortality is a thought experiment that relies on the many-worlds interpretation. However, it is also extremely difficult to prove wrong. The only way you could confirm this is if you attempted to kill yourself over and over (quantum suicide) and failed each time. But if you were wrong, you would die and not be able to tell anyone. Ergo, you cannot rule out the possibility that you will live forever.

The scariest part of the theory is not that you are potentially immortal. It is that quantum immortality does not account for your well-being – just your consciousness. If an accident were to leave you horribly disfigured but alert, it would still satisfy quantum immortality. You could be trapped in a motionless body for the rest of eternity, unable to communicate to anyone. Yet quantum immortality will keep you alive, forever and ever.

(Infinity Mirror Room by Yayoi Kusama)

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

Fusion

Posted on by Jinavie

One of the greatest challenges for modern science is unlocking the secret of nuclear fusion. Nuclear fusion presents the opportunity for humanity to obtain an extremely efficient yet surprisingly clean source of energy. Einstein’s famous equation – E=mc² – shows the relationship between energy and mass. It turns out that all matter is essentially energy, meaning that by breaking apart the matter to its basic constituents, you can unleash energy.

When two hydrogen atoms are collided together at extremely high speeds, the two protons join with enough energy to form deuterium, while releasing energy. As more hydrogens are collided, helium is formed while releasing more energy and also hydrogen, which can fuse with other hydrogen to start more reactions. This is a chain reaction. Once the chain reaction is established, the fusion reaction will keep producing immense amounts of energy until it uses up all the hydrogen available.

However, there are two main problems we are still trying to solve when it comes to unlocking fusion. The first is generating enough energy to kickstart the chain reaction in the first place, which is called ignition. The second is containing this immense energy, as the intense heat produced would melt any material we can produce to contain it.

This brief overview of nuclear fusion also offers a lesson in life. Most of the good things in life are not single events, but self-sustaining processes. Things like good habits, happiness and human relationships. To form a good habit, you must invest incredible amounts of time, resources and willpower. To start a relationship, you need to make an effort to show the other person how much they mean to you. To be happy, you need to completely change the way you perceive the world.

The best things in life do not happen by accident, but because you made an effort to ignite the chain reactions. Of course, you will constantly need to maintain those reactions so they don’t explode on you, but at the end of the day, starting is really half the battle.

(Couldn’t come up with an appropriate picture for this article……..so here’s a gif of Groot dancing)

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.

image

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.

image

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.