Particle Physics

Science is very bizarre. If you took the force of gravity and compared it to a random household object, you would probably see them as very different. But apparently, gravity is no different than the object. You see, everything (and I mean everything) is made up of particles.

The Standard Model:

There are numerous different particles. How can one expect to classify them all? Well, this is why scientists devised a theory that grouped all known particles into a single model known as the Standard Model. It’s somewhat akin to a periodic table of the particles. The Standard Model incorporates all the particles that constitute matter, the particles that regulate forces, and the single Higgs boson particle that is so different from the others. The Standard Model is divided into columns and groups. The first three columns (or generations) represent the particles that make up different types of matter. The first column is the most abundant type, however. The fourth column is where the gauge bosons (also known as force carriers) are placed. Finally, the fifth column is occupied by the extraordinary Higgs boson. The different groups are the quarks, which make up protons and neutrons (both of which are hadrons; see below), the leptons, which are electrons and other small particles, and the gauge bosons, which regulate forces. Each particle is paired with a corresponding symbol.

The Standard Model of Elementary Particles.
The Standard Model of Elementary Particles. Mathematical values for these particles are also displayed, the key for which is located in the upper-left corner.

Particle Properties:

The values shown along with each particle represent (from top to bottom value) the particle’s mass (total energy and momentum of a particle), charge (simply the electric charge of a particle), and spin (the rate at which a particle’s inertia causes it to accelerate).

Quarks:

Quarks are part of the fermion particle family. Quarks are the constituents of hadrons. Hadrons are divided into two categories: baryons (protons and neutrons), which are two up quarks and one down quark, and mesons, which are quarks bound to antiquarks. In addition, a third theoretical hadron category called a tetraquark is also plausible, and some theorists say that humans will eventually be able to create another periodic table using tetraquarks. There a six known types (or flavorsof quarks. Up and down quarks are the most stable, while the heavier charm, strange, top and bottom quarks rapidly decay. Quarks are bound together via the strong nuclear force (see the “The Four Fundamental Forces” post), which is in turn mediated by the gluon.

Leptons:

Along with quarks, leptons are part of the fermion particle family. Like quarks, leptons have six flavors. The most stable are the electron (also the most well known) and the electron neutrino. The heavier flavors are muons, muon neutrinos, taus, and tau neutrinos. Leptons are very important in chemistry as they are what give elements their distinct chemical properties.

Bosons:

Bosons are their own class of particles, like the fermions. Bosons are responsible for mediating every known force. Photons are the basic particles of light and mediate electromagnetism (see the “The Four Fundamental Forces” post). Gluons mediate the strong nuclear force. W bosons and Z bosons both mediate the weak nuclear force. The graviton is a hypothetical particle that is theorized to mediate gravity. Finally, the Higgs boson, discovered in 2013 using the Large Hadron Collider in Switzerland, mediates mass itself.

Problems with the Standard Model:

The Standard Model has been described as a “Theory of Almost Everything”. However, it has been pointed out that is does not account for the hypothetical dark matter, dark energy, and other anomalies.

The Four Fundamental Forces

When scientists say “force”, they usually aren’t referring to the mighty power used by the Jedi to hurl people across the room. In science, a force is any interaction between two or more things that causes them to change. There are four fundamental forces in nature.

A generic illustration of various forces.
A generic illustration of various forces.

Gravity:

Gravity is easily the most well-known force in nature. It is what keeps us bound to Earth. It is what stops a balloon from exiting the atmosphere. Contrary to popular belief, gravity does not pull down (in fact, there is no such thing as “down”). In technical terms, gravity is the force that attracts objects towards the area with the highest mass. For example, the Earth orbits the Sun because the Sun has a higher mass.

Electromagnetism:

Don’t be frightened by the long word. It’s actually very simple if we break it down. “Electro” refers to the electric charge that atoms possess. Magnetism just means the attraction or repulsion of things. Therefore, electromagnetism is the force that regulates the attraction between oppositely charged particles and the repulsion of particles with the same charge. Electromagnetism has numerous derivatives, including friction and pressure. Electromagnetism is also the force that allows light to move on it’s own.

Strong Nuclear Force:

The strong nuclear force is the force that binds protons and neutrons together to form atomic nuclei.

Weak Nuclear Force:

The weak nuclear force is the force that causes radioactive decay and nuclear fusion of atoms and subatomic particles.

Potentially Habitable Exoplanet?

NASA recently discovered a new exoplanet roughly 490 light years from Earth. This planet was discovered to be orbiting the star Kepler 186, which is known to have 5 other orbiting planets, and so the new one was named Kepler 186f. Kepler 186f is estimated to be 10% larger than Earth. But the interesting thing about this planet is that it sits within the “habitable zone” of its host star. This means that it is warm enough to sustain life but not be incinerated in the process. The temperature allows for liquid water to exist on the planet. However, scientists do not have the technology required to analyze the atmosphere of such a distant planet, and therefore do not know if the air is breathable.

This video explains more about Kepler 186f

Radioactive Decay

You may have heard the term “radioactive”. A lot of the time, it is associated with green goo, superpowers, and mutant creatures. Of course, those things don’t actually happen in real life. In real life, radioactive decay is a scientific process which I will explain.

Types of Radioactive Decay:

Radioactive decay is a process that occurs on the atomic scale. Unstable atoms have unbalanced electrical charges, meaning the subatomic particles that make up the atoms want to balance out the charge. To do this, subatomic particles are ejected from the atom, along with excess energy. Ejected particles and energy is collectively known as radiation. There are three types of radioactive decay: alpha decay, beta decay, and gamma decay. Alpha decay is when two protons and two neutrons are ejected from the atom. The combination of protons and neutrons emitted is identical to the nucleus of a helium atom. Beta decay is when beta particles, which are either electrons or positrons, are emitted. Finally, gamma decay is when a simple energy surge called a gamma ray is released. The time it takes for a particular element to decay is called a half-life.

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Products of Radioactive Decay:

Radioactive decay can result in the production of different isotopes or entirely different elements. Because of the protons and electrons (positrons in the case of antimatter) ejected, beta decay and alpha decay always result in the formation of different elements. Atoms that have yet to undergo radioactive decay are called parent atoms. Atoms that are the result of radioactive decay are called daughter atoms. In alpha decay, the emitted protons and neutrons are identical to the helium nucleus, and therefore equal helium. In addition, the remaining nucleus of the parent atom has been deprived of two protons, and therefore goes down two atomic numbers. For example, uranium is a completely unstable element with the atomic number 92. When it undergoes alpha decay, a helium nucleus is ejected and the remaining nucleus becomes thorium, which has the atomic number of 90. Beta decay also transmutes elements. For example, when a potassium atom ejects electrons, it will decay into either calcium or argon (scientists believe this is selected completely at random). Gamma decay does not transmute elements, because gamma radiation is pure energy.

Nuclear Fusion and Fission

People commonly associate the term “nuclear” with the term “boom”, due to the fact that these processes can indeed cause chaotic explosions. But what exactly happens to cause a nuclear explosion? While I will talk about the inner workings of atomic bombs when I get to the “Nuclear Weapons” post, here I will explain two important scientific processes.

First off, lets establish that “nuclear”does not actually mean “boom”. Nuclear actually refers to atomic nuclei, the cores of atoms. The processes of nuclear fusion and nuclear fission both involve these nuclei.

Nuclear Fusion:

Fusion in the Sun typically follows this chart. The other labeled particles are byproducts of the reaction.
Fusion in the Sun typically follows this chart. The other labeled particles are byproducts of the reaction.

Fusion is the name for two objects colliding, merging, or otherwise connecting. To understand nuclear fusion, you first have to understand particle movements. Atoms with a lot of energy like to use up that energy, like a toddler charged with sugar. For example, when you boil water, you are giving the water molecules heat energy, which makes them want to loosen up and move all over the place as steam. Because of how fast the water is now moving, the particles smash into each other and knock each other around. What happens when you add even more heat? With a lot (and I mean a lot) of heat, the steam will become ionized (see the “The Four States of Matter” post for more information), meaning the electrons that buzz around atomic nuclei will take off and roam independently. At this point, the water is the state of matter called plasma. Stars are very, very hot. This means they are made entirely of plasma. Not water plasma, though. Hydrogen and helium plasma. Because the hydrogen nuclei are so “excited”, they constantly ram into each other. This collision causes the nuclei to lose mass, which is expelled as photons, particles of light energy. Mass can also be expelled as heat. Due to the sheer amount of collision inside the star, it will begin to be very hot and very bright. But the process doesn’t end there. Even after the energy is released, hydrogen atoms “mingle” until they are clumped into groups of four. The results are called helium atoms, because the number of protons has gone from one to two. Hydrogen and helium aren’t the only elements that can fuse, but they are the most common. Heavier elements are much less likely (and much more difficult) to fuse together.

 

Heavier elements can also fuse together. This diagram shows typical fusion in heavier stars. Notice how elements like nitrogen and oxygen are present.
Heavier elements can also fuse together. This diagram shows typical fusion in heavier stars. Notice how elements like nitrogen and oxygen are present. Nuclear fusion is how many of the heavier elements in the universe were first formed.

Nuclear Fission:

Fission refers to the process of ripping something apart, in this case atomic nuclei. Unlike fusion, which tends to occur in lighter elements, fission tends to occur in heavier elements. In nuclear fission, atomic nuclei are torn apart, releasing tremendous amounts of stored energy, and creating two or more lighter atoms. This is why heavier elements are better fissioned than fused. For example, uranium can split into barium and krypton when it has enough energy. A lot of the energy is released during the reaction.

A diagram of the nuclear fission of uranium into barium and krypton.
A diagram of the nuclear fission of uranium into barium and krypton.

The video below is superb in explaining nuclear fusion and nuclear fission. And it even does so with the help of the evil computer from Valve’s Portal series!

Genetics

Have you ever wondered why you look like your parents? Well, every person inherits chemical information from their parents. These chemicals instruct the cells in the body to produce certain proteins, which determine each person’s physiology. The branch of science that studies these chemicals is called genetics.

DNA:

A color-coded strand of DNA.
A color-coded strand of DNA.

 

To understand genetics, you first have to understand DNA. DNA is short for deoxyribonucleic acid. DNA is a complex macromolecule composed of two main things: four different chemical “bases” called nucleotides, and a “backbone” of alternating sugar (in this case, deoxyribose) and phosphate. The nucleotides, also called nucleobases, are important chemicals. They are adenine, thymine, cytosine, and guanine (often abbreviated ATCG). The sequence of these nucleotides in a DNA molecule is what determines the proteins the molecule codes for. Like letters of the alphabet, there are numerous ways of rearranging the bases. DNA looks somewhat like a twisted ladder (in science, this shape is called a double helix). The sides of the ladder are made of sugar and phosphate, while the rungs are made of the four chemical bases. Each rung is made of two connected bases. Adenine always pairs with thymine, while cytosine always pairs with guanine. Thymine and cytosine are known as the pyrimidines, while adenine and guanine are known as the purines.

RNA:

RNA is like DNA, but differs in multiple ways. RNA is short for ribonucleic acid. Unlike DNA, RNA has only one strand. Additionally, RNA uses the nucleobase called uracil instead of thymine. Finally, RNA contains the sugar ribose instead of deoxyribose. RNA serves to deliver direct instructions to organelles. Arguably the most important task is to instruct the ribosomes on protein synthesis.

Genes:

In genetics, the term “gene” is only loosely defined. However, it is most commonly used to refer to any polymer (long, repeating strand) of DNA or RNA. Genes code for the production of different proteins. The different proteins are responsible for physiological differences between living beings. Any variation of a gene is called an allele. Each allele codes for a different trait. A person’s collection of physical traits is called their phenotype. A person’s collection of genetic traits is called their genotype. There are two types of traits: inherited traits, which are directly genetic in nature, and environmental traits, which are the result of external factors. Some traits can be influenced by both the environment and inheritance.

Chromosomes:

Genes are located on chromosomes, small cell structures that lie within the cell nucleus. While most chromosomes look like the letter ‘X’, circular ones are also known to exist. They are made of tightly coiled pieces of DNA, RNA, and proteins.

Below is a song about DNA (this is a parody of “Grenade” by Bruno Mars)

 

Muscular System

Muscles are what let you move from place to place. They are what let you stretch your arms. Even simple finger movement cannot be done without muscles. Collectively, the muscles in the body are referred to as the muscular system.

A simplified diagram of the anterior and posterior views of the muscular system.

 

Role of the Muscular System:

The muscular system allows movement of the body by applying force. There are numerous muscles in your body, so many it would be difficult to memorize them all. However, there are multiple notable muscles with notable functions.

Shoulder Muscles:

Shoulder muscles raise and lower the arms.

Triceps:

The triceps straighten the arms and keep them in place. They are located above (outside) the biceps.

Biceps:

Biceps are muscles that bend the arms. They are located beneath (inside) the triceps.

Neck Muscles:

Neck muscles allow the head to move in a wide variety of directions.

Abdominal Muscles:

Abdominal muscles move the torso.

Thigh Muscles:

Thigh muscles allow movement in the the legs.

Shin Muscles:

Shin muscles allow the feet to move around and side-to-side.

Calf Muscles:

Calf muscles control the heel and toes.