Laws of the Universe (6/11): Quantum Physics Part 1 (Fundamental Wave Concepts and an Introduction to Wave-Particle Duality)

Waves

Waves are defined as the movement of energy over a particular distance without the net movement of particles that mediate it. This basically means that when a wave is created energy is transferred from particle to particles causing them to move up and down (transverse) or side to side (longitudinal) but they always return to their original position.

The fundamental anatomy of a wave (amplitude, wavelength, frequency and speed) are all studied through year 8 – 10, so I will not spend time discussing them, instead, in this section, I will discuss, refraction, dispersion, interference and diffraction with references to famous experiments.

Refraction

Refraction is loosely defined as the bending of light through different mediums. So why does it happen? Well, when light is modelled as a wave and travels through different mediums, it interacts with the different particles within that medium. For example, when light travels through glass, the light interacts with the molecules of sodium carbonate, calcium carbonate and particles of sand, and these interactions slow down the passage of light through the lattice structure of glass. Comparatively, when light travels through air the particles that it interacts with are very loosely packed together as it is in a gaseous form, in fact, in the vacuum of space there are very, very few particles for the light to interact with hence it can follow a straighter path and thus travel at its true speed of 3*10^8 m/s. This holds true for other types of waves as well such as sound waves which also travel through a medium. So how does this relate to refraction? Well, as a beam of light travels between mediums of varying refractive indices, it bends towards or away from the normal. If the beam goes from high index to low index it bends away from the normal and vice versa.

Dispersion

Dispersion is a similar concept to refraction in the sense that it involves the bending of light trough different materials. As we know, white light is a combination of the colours of the electromagnetic spectrum (ROYGBIV) and they all have slightly varying wavelengths and frequencies. When white light is shone through a glass prism, it splits into its component colours. This is because of their varying wavelengths, this is shown by the organisation of colours in a prism from the long wavelength at the top and low wavelength at the bottom as shown below.

Interference

Interference can be in 2 forms, constructive and destructive. Constructive interference is when the crests of one wave meet the crests of another wave. This causes the amplitude of the resultant wave to increase but retains the wavelength and the frequency. Destructive interference, on the other hand, is when the crest of a wave meets the trough of another wave, causing the resultant wave to have a decreased amplitude and maintain the wavelength and frequency. In 2 incident light waves, when their crests meet, they produce of very bright band of light.

Diffraction

Diffraction of waves is the deviation of waves around corners or small gaps. When a wave moves through a small gap, it bends away from the corners according to Huygens’s principle. It states that wavefronts (crests in 2-dimensions) are created by the interference of points emitting waves and when these points encounter a gap, the wave points on either end of the gap extend their wave out without restriction thus allowing diffraction to occur.

Wave-Particle Duality: The Debate of the Ages

For millennia physicists have debated over the nature of light, the key models put forward are the wave model and the particle model. The wave model suggests that light behaves like a wave and is a net transfer of light energy whereas the particle model suggests that light is a stream of particles like a beam of hot steam. 2 key experiments were conducted to determine the nature of light and are outlined below.

Young’s Double Slit Experiment

A famous experiment used to determine the wave nature of light was Young’s double slit experiment. Although the original intention of the experiment had to do with optics rather than quantum mechanics it still supports the wave model of light elegantly. The experiment is set up with a detection screen placed a known distance away from a thick opaque film that has 2 very small slits in it. Monochromatic light is shone through these slits and the pattern is observed on the screen. If the particle model of light is to be accepted, then there should be 2 clear bands of light however the result of the experiment showed a series of alternating bright and dark bands. This was a monumental discovery as it suggested that not only did light diffract but also interfere. The dark bands of the pattern indicate destructive interference where the crests of light from one slit meet the trough of the light from the second slit. This is caused by the length of distance that 2 beams of light that have to travel, this difference is known as the path difference. This shows that as light exhibits phenomenon which is exclusive to waves, it must be a wave. The experiment is outlined below.

The Photoelectric Effect

The photoelectric effect is an experiment which contradicts the wave model of light. A beam of monochromatic light is shone on a particular metal and this results in a release of electrons from the lining of the metal. These electrons are detected by a wire and a current is observed by the sensor. This is known as the photo-current. This is fairly simple stuff, energy is applied to a metal and the electrons get excited and they leave the surface of the metal. A contradiction occurs however when it is found that there is essentially a 0-time delay between the light switched on and the detection of a photo-current, which is inconsistent with the wave model, which suggests that there should be a time delay to allow for the energy to be fully absorbed. Another contradiction is that upon increasing the intensity of light the total energy of the electrons was constant (ie kinetic as measured using the stopping voltage, refer to Units 4 Physics textbook) but the photo-current was increased. And finally, there was a certain amount of frequency required to free the electrons, any frequency below that wouldn’t work, not even an increase in intensity.

So… A dilemma

This was a problem, there was good evidence for and against the wave model but which one was correct? Well, scientists theorised that maybe light was a stream of particles, called photons, that would hit and be absorbed by the electrons on the metal sheet in the photoelectric experiment. This would explain why there was an instantaneous release of electrons and why increasing the intensity (ie increasing the number of photons) would result in more electrons being released (due to more collisions). But this still didn’t fully explain how a particle like a photon could diffract and interfere. Well, it was theorised that maybe it was both, when we looked for wave properties we could find them and when we looked for particle properties we could find them too. This led to the development of the Theory of Wave-Particle Duality.

Wow… this was really long, next week I will finish off Wave-Particle Duality and start talking about Heisenberg’s cat and some Quantum Tunneling, so tune in and tell your friends to read this series!!

Laws of the Universe (5/11): Particle Physics Part 3 (Bosons, anti-matter, Fundamental forces)

Bosons and the Fundamental forces

Bosons are the force carriers of the universe, they mediate the four fundamental forces of nature, the weak force, the strong force (genius level naming right), the electromagnetic force and the force of gravity. The W and Z bosons mediate the weak force, the graviton mediates the force of gravity, the gluons mediate the strong force and the photon is responsible for the electromagnetic interactions.

The Weak force

The weak force, when mediated by W and Z bosons, is responsible for beta+ and beta- decay of atoms. Beta decay is responsible for changing one atom into an isotope of another. For example, beta- decay is the spontaneous conversion of a neutron in a nucleus into a proton and an ejection of an electron (or a positron) and a neutrino (a lepton). Beta+ decay, on the other hand, is the conversion of a proton into a neutron with an ejection of an electron (or a positron) and an anti-neutrino (more on this in this article). During a beta decay reaction, W and Z bosons work together. Z bosons, however, carry no charge and only serve as a “catalyst” for the two types of W bosons, W+ and W-. W+ bosons are responsible for beta+ decay (which changes a proton into a neutron, electron/positron and a neutrino). If a positron is created it gets annihilated and the neutrino gets ejected out of the atom, if an electron is created it gets ejected along with the neutrino. W- bosons are responsible for beta- decay, (where a neutron turns into a proton an electron/positron and an anti-neutrino). The anti-neutrino (and if the positron is created) gets annihilated and the electron is ejected from the atom as the beta particle.

The Strong Force

The strong force is the force that essentially holds together our universe, it is the force that is responsible for the attraction between quarks and anti-quarks within a particular hadron. These gluons not only attract quarks and anti-quarks but also quarks and other quarks, these are responsible for the many different pairs and valence pairs present in a hadron. As we know quarks have a colour charge; red, blue or green which cancel out to make white, therefore the force which binds them must have a corresponding colour charge. Gluon colour charges are formed by a colour and corresponding anti-colour for each of the binding pairs inside a given hadron. This combination of colour and anti-colour allows every “type” of quark to bond with every “type” of anti-quark. This theory is vital is explaining why the different quarks can coexist inside a hadron without violating the Pauli Exclusion Principle (which states that two or more identical fermions (particles with half-integer spin) cannot occupy the same space unless they are bonded with other matter).

The 9 gluon flavours are as follows:

Red + Anti-red	Red + Anti-blue	Red + Anti-green
Blue + Anti-red	Blue + Anti-blue	Blue + Anti-green
Green + Anti-red	Green + Anti-blue	Green + Anti-green

The Electromagnetic Force

The electromagnetic force is one of the most common forces in nature and it is mediated by the photon (basically light particles, more on this later) in the form of light and energy. It is studied in Unit 3&4 Physics in the form of magnetism and electricity hence I won’t delve into it here. It travels at the speed of light in the form of waves moving at right angles to each other (more on this later). Photons are created constantly in particle collisions such as those in a particle accelerator. Photons are thought to carry no mass and no charge. It has an integer spin and it is one of the particles which take part in electroweak (low energy) interactions (along with the W and Z bosons).

The Gravitational Force

The gravitational force, first theorised by Isaac Newton in July 1687, has now become a huge part of quantum mechanics and particle physics. The equation proposed by him,  (refer to Introduction to Classical Physics) however becomes inapplicable at the quantum level. Therefore, to unify the theory of gravity with quantum mechanics, the standard model makes use of a gauge boson called the graviton to illustrate this force at the quantum level. Like the photon, it is also a massless particle carrying no charge. The graviton is a theoretical particle that has recently been supported with substantial evidence due to the observation of gravitational waves. Superstring theory does prove its existence using string mathematics yet the use of superstring theory (more on this later) hasn’t been incorporated into the standard model due to a lack of physical evidence and experimental data.

The Higgs Boson

The Higgs boson is the only boson that is a part of the scalar bosons. It is the boson which is responsible for providing mass to all the particles in the universe. All particles reside on the Higgs Field which stretches out throughout space-time, this field acts like water all the particles “swim” through it, it provides “drag” to all the particles which it effects thus causing the property we recognise as mass. It is important to differentiate the Higgs Boson from the Higgs field; if the Higgs boson is a droplet of water the Higgs field is water vapour in which it is suspended (Neil Tyson). This suggests that the Higgs field is the fabric that potentially encompasses all dimensions (more on this later) and the Higgs bosons are the tiny particles of cloth which make up the fabric. The Higgs boson is the mediator of the Higgs field and it is the “God particle” as it is theorised to be one of the first particles to come into existence after the Big Bang.

Anti-matter

Anti-matter is a huge part of the standard model as they help balance out the matter in terms of charge (They were last mentioned in Particle Physics Part 2: Spin and composition). Anti-matter particles are represented mathematically by the normal particle symbols with a bar above them (eg. u-bar, is an anti-up quark). Anti-matter has the same mass and spin but the opposite charge to matter. One way to understand this is through simple mathematics, for example solving for (x) in the equation (x^2 = 4), results in two answers, -2 and +2 and this idea holds for particle charges as well. The anti-matter counterparts of quarks are anti-quarks and the anti-matter of electrons are anti-electrons (commonly known as positrons due to their positive charge). When anti-matter collides with matter they annihilate each other, as they do this they release energy in the form of photons (which have no anti-matter version). Anti-matter can also produce anti-protons and anti-electrons thus being able to produce the anti- version of any given atom, however, this is not possible on a large scale as they would be quickly destroyed when they interact with matter. This is the reason why we haven’t been able to see anti-matter on a large scale before, one of the most common anti-matter element we have seen is anti-hydrogen. It consists of an anti-proton (made up of 2 anti-up quarks and an anti-down quark) being orbited by a positron.

Sorry for the delay between the this post and the last one, I’ve been really busy with school work because of exams, please share this post with others and I hope you learnt something new today, see you next week with a post that introduces key wave concepts!!

Laws of the Universe (4/11): Particle Physics Part 2 (Quantum spin and Composition of protons and neutrons)

Quarks are essential to the formation of larger particles. Particles that are composed of 2 quarks are called mesons, and particles that are composed of 3 quarks are called baryons.

Last week we discussed the properties of quarks such as charge and mass. Today we will be discussing quantum spin, quark pair separation and the composition of larger particles.

Spin

Spin in quantum physics is different to spin as it is understood in everyday life, it is an expression of angular momentum at the quantum level, where the charges of elementary particles “spin” on their own axes within a given particle. In saying this, I mean that the charge oscillates between positions within the particle. This movement of charge creates a weak magnetic field around the quark. The existence of this magnetic field is the reason why adjacent electrons (which are elementary particles) need to have opposite spin to exist in the same orbital. This is shown by the diagram above, if one electron has a spin that is positive (indicated by the upward arrow) it has to be paired with an electron that has a negative spin (indicated by the downward arrow). Spin can be represented by a vector quantity; the reduced Planck constant. Planck’s constant (h) is the energy of a photon (at rest) divided by the radiation frequency of a photon h=E/v or E=hv, where (E) is energy, (v) is the radiation frequency (or simply velocity) and (h) is Planck’s constant. A simplified version of this constant is the reduced Planck constant (ħ) which equals h/2π. Hence, we can merge the two equations to get energy in terms of the reduced Planck constant (ħ) and the radiation frequency (v) in the form E=2πℏv . By this definition, the spin of fermions can be calculated to be in the form nℏ/2 and the spin of bosons to be nℏ where n is an odd integer and ħ is the reduced Planck constant. Collectively the reduced Plank constant (ħ) is known as the quantum of spin. Thus, we can say that bosons have a full integer spin while the fermions have a half-integer spin. Alongside the different integer spin, fermions are theorized to consist of matter whereas the bosons are considered as force carriers, meaning that the fermions obey the Pauli exclusion principle (which states that no two fermions can have the same quantum spin or state at the same time, e.g. if an electron in the first orbital of an atom has positive ½ spin the electrons in the second orbital will have – ½ spin thus cancelling each other out) and the bosons do not.

Quark Pair Separation

Quarks bond with each other or anti-quarks [next week] through the quantum energy of gluons to make hadrons. It is impossible to find a single quark by itself as they are always bonded to another one by a gluon. The amount of energy required to split the pair is greater than the energy required to create two new quarks as the input energy, therefore before the quark pair has split them there will be enough energy in the system to create 2 new quarks or antiquarks. How can energy be converted to mass, well, this is because the energy put into the system of quarks follows Einstein formula, E = mc2 where the excess energy gets converted into mass by following the Law of Conservation of Mass.

Proton and Neutron Composition

Quarks make up two of the most common hadrons in the universe, neutrons and protons. Protons are made up of millions of quarks and anti-quarks all coming in and out of existence (due to the Heisenberg Uncertainty principle and Einstein’s formula) through the energy that is comprised in the proton. The different quarks can be of any kind given that they are bonded to their corresponding anti-quark that has an opposite charge thus cancelling each other out. For example, an up quark could spontaneously be created but it would have also had to be created with an anti-up quark which has the opposite charge. So how can protons have a charge? And why are neutrons at a neutral charge? This is because alongside the millions of quarks coming in and out of existence, there are also “valence” quarks that are not bound to anti-quarks but rather other matter quarks. This doesn’t mean that they are on the outer layer of the hadron however, this means that they are the quarks responsible for determining the charge of the hadron in question. For example, the proton has a charge of +1, therefore, they are made of 2 valence up quarks (with charges of +2/3 each, which add up to +4/3) and a valence down quark (with a charge of -1/3). When these valences of charges are added up you would get an overall charge of +1, corresponding with the charge of a proton. Similarly, neutrons are made of 2 valence down quarks (with an overall charge of -2/3) and a valence up quark (with a charge of +2/3) thus cancelling out to have an overall charge of 0, as a neutron should have.

Next week we shall discuss my favourite section of particle physics, Anti-matter, as well as the 4 fundamental forces and bosons, so tune in next Monday!!

Laws of the Universe (3/11) : Particle Physics Part 1 (Fundamental Particles and their Properties)

Particle physics is the study of the smallest objects in the universe. This study goes smaller than molecules, compounds, even smaller than atoms and protons. Particle physics is a study of the subatomic particles which form larger particles such as protons and neutrons.

The Standard Model

The main goal of the standard model is to unify all the known forces of nature and provide descriptions of how different particles are formed. The standard model consists of the explanations for all the fundamental forces, namely being, the strong force, the weak force, the electromagnetic force and the gravitational force. The standard model has succeeded in providing theories on how the first three forces are brought about and how they interact by making use of fundamental particles. The explanation provided by particle physics for gravity, however, has not been proven.

Fundamental Particles

Fundamental particles as defined by particle physics are those particles which cannot be divided any further. There are three kinds of fundamental particles, quarks, leptons and bosons. Quarks are the most common of these and they are responsible for the composition of larger particles. Leptons are the smallest particles and they are very rare, a common example of a lepton is the electron. Bosons are also known as the force carriers, this means that they mediate the four fundamental forces. Before we can talk about the individual types of particles it is important to understand the classification of them first.

All particles can be divided into 2 distinct branches, hadrons and leptons. Hadrons are particles that are comprised of 2 or more quarks. Hadrons are further divided into 2 branches, mesons and baryons. These form the elementary particles which are divided into bosons and fermions where bosons are the force carriers with full integer spins and fermions are the matter particles with half-integer spins.

A diagram summarising this information is shown below.

Quarks

There are 6 different types or flavours of quarks that can be found in the universe, namely, up quarks, down quarks, top quarks, bottom quarks, charm quarks and strange quarks. The different types of quarks can be differentiated from each other by observing their different properties such as mass, charge and spin and are detailed as follows.

Mass

All the flavours of quarks have their own unique mass but the lightest of the quarks are the up and down quarks and thus are the most stable. All quarks go through constant collisions in attempts to break off into lighter quarks so that they can be more stable and then ultimately become up or down quarks. This table shows the values of mass for the different types of quarks. The masses of these quantum particles are measured in MeV (one million electron volts or megaelectronvolts) and GeV (1 billion electron volts or gigaelectronvolts). Now the obvious question arises, how can a measure for energy in the form of electron volts equate to mass? This is simply due to the direct application of Einstein’s equation E = mc^2. To determine the mass of these quarks in kilograms substitute the E values as listed in the table and the light constant as c. For more information on Einstein’s energy equation refer to Part 1: Introduction to Physics and Energy.

Charge

When there is a discussion of charge in particle physics and quantum mechanics it is in reference to the electromagnetic charge that is generally associated with protons, neutrons and electrons. One clear and major difference, however, is the value of this charge. Quarks have charges in multiples of 1/3, these values can be positive or negative and these fractional charges are responsible for providing the larger particles with their charges. The charges for the different quarks are outlined below. It is important to notice that the top, charm and up quarks have double and positive charges when compared to their counterparts (bottom, strange and down respectively). This means that when found in certain ratios within a larger particle they can effectively cancel each other out. This idea will be further explored in the next section.

Quark	Charge
Up	+2/3
Down	-1/3
Charm	+2/3
Strange	-1/3
Top	+2/3
Bottom	-1/3

Laws of the Universe (2/11): Introduction to Classical Physics

Classical Mechanics: An introduction

Classical physics by definition is the study of physics in a classical manner. Much of modern physics is based on theories developed in the classical era of science which lasted from the early first century to the late 18th century. The classical era of science was revolutionized with the rise of quantum mechanics. For simplicity, the term classical physics in this section will focus mainly on classical mechanics. Classical mechanics is the set of laws introduced by Sir Isaac Newton in his book Principia Mathematica. As much of this section will be covered in the VCE study design for both Physics units 1 to 4, I won’t delve into the details as much as I would for the other parts in this series.

Newton’s laws of motion

Newton’s first law of motion states that all objects that are at rest will remain at rest unless a net force is exerted upon the object. This law of motion is also identified as the law of inertia. This law is the key in allowing the derivation of the formulae used to calculate the uniform motion of perfect bodies.

Newton’s second law of motion states that the force exerted on a body is its mass multiplied by the acceleration it is experiencing. In other words, F = ma. This force is revolutionary as it defines that the net force would equal 0 when the acceleration is 0. even though this sounds simple enough, it means that an object travelling at a constant velocity would have the same net force as an object at rest.

Newton’s third law is by far the most quoted and equally one of the most misunderstood laws of all. It states that every action has an equal and opposite reaction. In terms of motion, this is vital, as it superimposes the normal force against the force of gravity. This allows objects to resist particular forces and allows the motion formulae to come into effect.

Newton’s law of universal gravitation and other discoveries

Newton’s law of universal gravitation was a revolutionary idea at the time of its introduction and it continues to shape our understanding of gravity today. The law states that a particle attracts every other particle in the universe which is expressed by a force which is directly proportional to the product of the objects’ masses and inversely proportional to the square of the distance between their centres’ of masses. This law can be written in mathematical notation as follows:

F = G (m1xm2)/(r^2)

Where F is the force in newtons

G is the gravitational constant 6.674×10−11 N·(m/kg)2

M1 and M2 are the masses in kilograms

R is the distance in meters

It should be noted however that the value for G was derived over a century after the publication of the Principia Mathematica and in the original formula, the scientists could only find the force of gravity relative to other forces.

Alongside the 3 most well-known laws of Newtonian motion and the law of universal gravitation, an explanation of Kepler’s laws of planetary motion and the foundation for the uniform acceleration formulae are the key achievements made by the Principia Mathematica.

Limitations of Classical Mechanics

Despite the achievements of classical mechanics, it is but a crude form of physics and has many inaccuracies and limitations, for example, the universal law of gravitation itself is an inaccurate description of the force of gravity as Albert Einstein pointed out. He proposed that rather than exhibiting a unique force, gravity is actually the result of the changes in momentum due to the curvature in the fabric of spacetime. This theory is known as the theory of general relativity and it is the currently accepted explanation for gravity.

A limitation for the universal law of gravitation as put forward by Isaac Newton is the fact that its inapplicable for objects smaller than a grain of sand, or objects travelling close to or at the speed of light. This idea was also raised by Albert Einstein as it was clear that photons (in the form of light) were clearly affected by gravity when in close proximity to black holes, hence Newton’s law of universal gravitation was limited to celestial bodies not travelling at the speed of light.

Summary

Physics is an ever-evolving field of study and by no means is it perfect yet, however with advancements in our understanding of physical phenomenon we have proven that there are more accurate means of describing gravity and other concepts than those put forward by scientists in the classical era. We have already touched on Einstein’s theory of relativity, however, this is not the main focus of this series. This series aims to focus on things at the subatomic, the quantum level so it’s fitting if in the next section we will be focusing on the make-up of the universe, from atoms to electrons and from protons to quarks.

The next section (posted next Monday) will be the first of two sections on Particle Physics.

Laws of the Universe (1/11): Introduction to Physics and Energy

In this 11-part, fortnightly series we will venture through the realms of particle physics, quantum mechanics and superstring theory to devise a set of laws to describe the universe so join me, Nipun Kapadia, on this journey to determine the Laws of the Universe.

Physics – the spearhead of scientific pursuit around the world. It is one of the three major branches of science, the others being chemistry and biology. From this broad umbrella term ‘physics’, branches of the study of physics range from classical motion to quantum mechanics from thermodynamics to fluids and from energy to astrophysics.

We will be focusing on four major aspects of physics:

• classical physics, consisting of classical motion, thermodynamics and energy
• particle physics, dealing with subatomic particles
• quantum mechanics, which consists of particle-wave interactions, quantum entanglement, uncertainty principle, fluctuations in the quantum field, quantum tunnelling and quantum applications.
• superstring theory, which aims to unify particle physics and quantum mechanics to a universal theory of matter and energy.

Why Physics?

The main goal of physics is simple, to develop a set of laws which define the way in which matter and energy interact with one other on a universal level. In other words, to determine laws which apply to literally everything in the world and how they are expected to interact with each other. Physicists over the centuries have developed many theories which tried to explain phenomena which were encountered by people around the globe. For example, the ancient Indians and Egyptians had been mapping the heavens for millennia before Aristotle who came up with his ideas regarding the properties of materials and gave us the first crude idea of atoms in the form of Atomos which he described as small indivisible spheres which make up the universe. This idea of physics is perfectly described in the words of Lord Kelvin who famously said, “There is nothing new to be discovered in physics now, All that remains is more and more precise measurement”.

Energy

For the most part, energy has been a concept that is used as a cornerstone in many discoveries and theories put forward, this is likely because the laws regarding energy are so easy to define and identify. Energy is a concept used in the 3 main forms of physics, classical motion, quantum motion and electricity.

In classical mechanics, energy is used as a description for an object’s capacity to do work and is measured in joules.

In quantum mechanics energy is used as an object’s capacity to:

1. Rotate about its own axis
2. To undergo quantum superposition and tunnelling
3. And exhibit a wave function

In the study of electricity and power, energy is used to describe the amount of power can be given off by a certain amount of energy. This can also be measured in joules or watts depending on the unknown variable.

Einstein’s equation of energy, E = mc²

As this series is based around the key concepts of quantum mechanics, particle physics and superstring theory, it is important to understand this simple equation of energy that has been proven multiple times by scientists all over the world.

This formula is a part of Einstein’s special theory of relativity and serves the purpose of proving the idea that the speed of light is the universal speed barrier, this is however not the application that serves our purpose. The equation ties together energy, mass and the speed of light where E is energy in joules, M is mass in kilograms and C is the constant for the speed of light in m/s. This equation can allow scientists to convert a given amount of potential energy into its corresponding mass relative to the speed of light and vice versa. This equation is particularly important in particle physics as it allows scientists to determine a particle’s energy and use that value as a measure of mass. This equation and its relative energy values will be referenced in later parts of this series; however, the mass values will remain in their energy forms as this is the standard procedure for scientists across the globe.

The next part will focus on classical mechanics, specifically Newton’s laws of motions and Newton’s laws of universal gravitation.

ISRIB – a drug with the potential to reverse the effects of brain trauma

 
The brain is one of the most vital yet delicate organs in the human body and, as a result, brain injuries are often severe and difficult to treat. Traumatic Brain Injury (TBI) is the most common and often irremediable of these injuries. It occurs when someone suffers a severe bump or blow to the head from an external force which disrupts the normal function of the brain. The effects range in severity and may include cognitive decline and memory loss. Affecting approximately 54-60 million people worldwide and being recognised as the leading cause of disability in children and young adults, medical scientists have long been searching for a cure and, in 2017, it seems they found a drug that could be just that.

 

ISRIB (Integrated Stress Response Inhibitor) is a synthetic drug that was first discovered in 2013 and was used to improve the memory of healthy mice. However, in 2017, Peter Walter and Susanna Rosi of the University of California, San Francisco found that it could also be used to treat and, in fact, reverse the effects of brain trauma in them as well. It works by blocking a part of a protective cellular system called the Integrated Stress Response (ISR). When cells are injured or diseased, ISR slows down the process through which genetic instructions encoded in DNA are translated into functional proteins. Thus, as the name suggests, ISRIB inhibits the ISR and allows the cells to override it. The effects of ISRIB in mice were long term as, after only a few administrations of the drug, it was observed that a process known as long-term potentiation, (the continuous strengthening of synapses based on patterns of recent activity) occurred due to the inhibition of ISR.

 

To conduct the experiment, Walter and Rosi first used mechanical pistols on the mice’s surgically exposed brains to inflict contusive injury (of the severity such as that likely caused by a motor accident). Four weeks later, the mice were taught to swim through a maze while being given cues to remember the location of hidden resting platforms. As could be expected, the healthy mice improved over time but the injured mice did not. However, after being given ISRIB for three days in a row, they began to improve at the same rate as the healthy mice and, a week later, could solve the maze just as quickly. Shocked by the results, the team repeated the experiment with different TBIs and tasks that the mice were given to complete to confirm the reliability of the drug and found that ISRIB was effective in all cases.

 

Understandably, much more research needs to be conducted on ISRIB before clinical trials commence and it is not unlikely likely that the drug may not be as effective on humans as it has been on mice, as is often the case.

 

 

However, the potential that it holds is incredible. Because of TBIs, thousands of people suffer with no hope of reverting to the way their life was prior to the injury. But, with ISRIB, as neuroscientist Carlos Borlongan said, they “[are offered] a glimmer of hope” to potentially even make a full recovery.

 

Elisa Karaim Year 11

Edited by Mariam Malak Year 11

The Large Hadron Collider: Exploring The Fundamental Particles Of The Universe

The discovery of the fundamental particles of the Universe allowed physicists to gain a new insight on what the conditions during the Big Bang was like. Using particle accelerators, physicists are able to imitate the extreme conditions that occurred a fraction of the nanosecond after the Big Bang. Particle accelerators such as SLAC and the Large Hadron Collider (LHC) in particular are specialised at testing the different theories of particle physics.

The Humble Trilobites

If you think it is impressive that primates have managed to survive on Earth for 50 million years, then you will find it phenomenal that trilobites managed to survive for a staggering period of 270 million years. First appearing on Earth about 521 million years ago during the early Cambrian period (when life on Earth began to complexify in incredible ways), they finally became fully extinct around 252 million years ago, during the late Permian period, and were probably the most abundant animal on Earth at that time. This is one testament to their immense success as an organism; another being the fact that their fossils are found widely dispersed on Earth – on every continent in fact – and palaeobiologists have named over 15,000 species of trilobites. So what made them so successful as an organism?

The Science Behind Fidgeting

Fidget spinners—the cool, new fad that everyone wants to get their hands on. It’s no doubt that this simple little toy has taken the world by storm, fascinating people by just spinning and spinning. Many people view the spinner, and similar fidget toys such as the Fidget Cube just as “toys”, but others use them for their intended purpose, which is supposedly to aid their concentration. So, does science prove or disprove this?

The Crazy Notions of a Super Genius

(Close to) 50 years after the death of Albert Einstein, I was hunched over my computer looking for a way to pass time, when I decided to acknowledge the crazy notions of a super genius. So here we go:

1. Moving objects gain weight, shrink in size and experience time more slowly than a stationary object. Crazy, but follows logically from Einstein’s Special Theory of Relativity (STR). Not only have the three ideas above been proven mathematically, but also experimentally. Although, quite sadly, we can’t experience the effects of STR in our day-to-day lives, NASA needed Einstein’s wisdom to get to the moon.
2. There is no way to know whether you are moving or simply stationary. This was enough to elicit the fury of physicists around the world. Silly as it sounds, it is again a logical idea. Ever look out the window of a moving train and ask yourself whether you are actually moving, or whether the background you observe is moving? Einstein did. And as a result of that nonsensical question, Einstein went on to assert that motion is relative. Only B can determine whether A is stationary or not. Moving on . .  .
3. Light is affected by gravity and can be bent. Or rather distorted by gravitational attraction. It was a solar eclipse that made Albert Einstein a scientific celebrity in less than 24 hours. His General Theory of Relativity (GTR) was proved when a very determined Englishman trekked to Africa to photograph and prove that during the solar eclipse light was distorted by 1.7 arcseconds, the precise predictions of GTR.
4. We can make portals through space and time. No, it isn’t just science fiction. Einstein proved for the first time that we can in fact time travel if we produce a wormhole. This gave the inspiration for Christopher Nolan to make his film Interstellar. Wormholes can also be used for teleportation. It is believed to be a wormhole that Coraline crawled through to reach the “Other Universe”.
5. The most famous equation ever. Also easily the most misinterpreted equation ever. Annoyingly, the mathematics used to obtain this equation is, according to the Heinemann Physics Textbook “outside the scope of this course”, but the equation itself is very simple. The total energy of an object is equal to the mass of the object when moving multiplied by the speed of light squared. When the object isn’t moving, the equation changes very slightly to , where is the “rest mass”.

However, as much as we can praise Einstein, he also made a widely publicised mistake. And then made another one. In fact, Einstein publicly rejected and completely abased a whole new branch of mind-bogglingly theoretical physics.

Wild Dog Thought To Be Extinct Rediscovered In The Wild

We’ve heard of many animals gone extinct – the dodo, the Tasmanian tiger; and we’ve heard of many being rediscovered by scientists after decades of ‘extinction’. This miraculous feat has once again been achieved in 2016, confirming the existence of another species previously thought to be extinct.

For over 40 years, the New Guinea Highland Wild Dog has been thought to be extinct in the wild. They are believed to be one of the rarest and most primitive species of canines, and a variant of the New Guinea Singing Dog (Canis dingo hallstromi) – the two are thought to once be the same species, before humans took wild dogs from the highlands and bred them into the Singing Dogs we know now. Although the Singing Dog are still bred in zoos, little has been heard of the Highland Wild Dog. However, in 2016, this all changed.

Lung Organoids

Organoids, it’s in the name. They are 3D, miniature and basic versions of organs that help scientists further understand the anatomy and function of various organs. Recently, researchers of Columbia University Medical Centre have created miniature lung organoids (as seen in the image bellow) to aid their knowledge on treating various diseases.

So how are they made? Technology has rapidly improved in the past 7 years and has been used for research in order to help scientists improve their understanding on biological functions. This technology began with attempts to create organs on a dish, which started as a dissociation – reaggregation experiment lead by Henry Van Peters Wilson. The results of this experiment showed that sponge cells could re-organise themselves after being separated, back into one whole organism. After this experiment, there were many similar experiments that were able to generate different types of organs artificially through the dissociation and reaggregation of organ tissues. These experiments often used amphibians as their subjects.

The Dimensions Of The Universe

Have you ever wondered whether or not parallel universes exist? And if they do, how is it possible? To answer this question, let’s take a look at the notion of dimensions. Dimensions are simply the different facets of what we perceive to be real. We live in a three dimensional world and are familiar with the components that make up the three dimensions – that is we see objects in our immediate world as having a length, width and depth.

However, it seems that the three dimensional world is not the limit. In the light of string theory, scientists now believe that there may be many more dimensions beyond the three we are familiar with. In fact, the string theory postulates that it could be possible that 10 dimensions exist in the universe.

CRISPR-Cas9 — A New Era In Molecular Biology

Imagine a world where, just like in food, human genes can be edited, giving people the power and ability to eradicate genetic disorders, but also unjustly provide a portion of people in the future with advantages over others. For better or for worse, this is likely to soon become a reality, with the recent invention and refinement of the genome editing tool ‘CRISPR-Cas9’.

Every aspect of who we are is determined by our genes, which are tiny units of heredity made up of DNA, which act as instructions for the production of proteins. It is estimated that humans have approximately 20,000 to 25,000 genes in total and although most of our genes are the same between all humans, the 1% or so that aren’t, are what gives each of us our individual traits. CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats and was originally discovered in certain species of archaea in 1993 by Francisco Mojica. Between then and 2013, scientists across the globe worked on developing a way to use this discovery to their advantage, ending up with CRISPR-Cas9. It differs from all previously developed gene editing tools and techniques because it requires considerably less time and effort to execute, and is substantially cheaper. The actual process does not require a lot of human involvement, because Cas9 (the enzyme that alters the gene) is “led” by guide RNA to the correct location, making CRISPR-Cas9 the most accurate gene editing tool yet.

The Invincible Tardigrade

Tardigrades (Phylum: Tardigrada), also known as water bears, were first discovered by the German zoologist, Johann August Ephraim in 1773.  They are water-dwelling micro-animals with eight legs and can reach a maximum size of 1.5mm. Now over 1000 individual species of tardigrades have been discovered to this day.

Tardigrades are some of the most resilient animals known and can be found in almost every environment, ranging from tropical rainforests to Antarctica, and even your own backyard! It is said that these tardigrades get to all these different places by being carried by wind and water currents and then deposited somewhere far away. If you have a microscope, it is actually possible to find your own wild tardigrades!

These water bears are renowned for their ability to survive extreme environmental stresses that would kill almost any other animal, such as being dehydrated, exposed to excessive amounts of gamma radiation and coping with pressures as high as 600 mega-pascals (MPa) – pressures that are beyond anything they might encounter in nature. They can also tolerate being frozen to -272.8 °C (which is just above absolute zero), as well as being heated to 151°C for 15 minutes and still bounce back to life. Not to mention, they can healthily reproduce in outer space! If you were to go into outer space without protection, you will die in only a matter of 15 seconds. The low pressure would force the air out of your lungs and the fluids in your body will expand, causing you inflate. Your capillaries would rupture and the ionising radiation would destroy the DNA in your cells.

So, the question is, how are tardigrades able to survive in these extreme conditions?