Standard model
Standard model.
Fermions.
Elementary particle properties.
Quarks.
Protons.
Neutrons.
Leptons.
Electron.
Neutrinos.
Meson.
Forces.
Electroweak force.
Bosons.
Gauge bosons.
The Higgs bosons.
Energy.
De Broglie wavelength.
Standard model : Atom to universe.
Anti matter.
Matter in the universe.
Standard model.
In the classical model, matter comprises of atoms.
Atoms comprise of a nuclei, in the centre,
around which the electrons orbit.
The nuclei comprises of protons, and neutrons.
All the elements in the periodic table,
can be identified using this model.
The size of the atom, is in the order of 10 to the power of minus 8 cm.
The size of the nuclei, which comprises of protons and neutrons,
is in the order of 10 to the power of minus 13 cm.
In this model most of the atom is empty space.
The model has now evolved more.
Protons, neutrons and electrons are no longer the most elementary particles.
Much smaller particles have been discovered.
The standard model describes the current understanding,
of matter and the fundamental forces.
It covers:
The sub atomic particles, known as fermions and leptons.
It also covers the fundamental forces:
The electromagnetic force.
The strong nuclear force.
The weak nuclear force.
The standard model currently does not cover gravity.
It also does not cover phenomena like dark matter and dark energy.
It is sometimes called the "Theory of almost everything".
The standard model is a paradigm of quantum field theory.
Fermions.
Fermions refer to a class of elementary particles.
Fermions are generally matter particles.
They have a half integer spin.
For example, they can have a spin of 1 by 2, 3 by 2, 5 by 2 etc.
Protons, neutrons, quarks and electrons are some of the particles,
that have half integer spin.
There are two categories of fermions.
Quarks.
Leptons.
There are six types of quarks.
There are six types of leptons.
There are a total of twelve fermions.
Sometimes it is referred to as the twelve flavours of fermions.
The mass of a particle is quantified in electron volts.
Mass and energy are inter convertible .
This is illustrated by Einstein's famous equation, E=mc squared.
Elementary particle properties.
The elementary particles are qualified with the properties, which are :
Electrical charge.
Colour charge.
Spin.
Electrical charge.
This refers to the electrical charge.
The electric charge is measured in the charge of an electron.
For example, a proton has an electrical charge of plus one.
A neutron has an electrical charge of zero.
A electron has an electrical charge of minus one.
A neutrino has an electric charge of zero.
Quarks have fractional electric charges.
Colour charge.
The term colour charge has no relationship to visual colour.
They refer to a property of elementary particles.
They are useful for defining certain rules like, colour confinement.
The three basic colour charges are :
Red, green and blue.
The combination of red, green and blue in visual colour is white.
By analogy the combination of red, green and blue colour charges,
is neutral.
When referring to colour charge, neutral charge is equivalent to white colour.
For example, protons and neutrons have a neutral or white colour.
Each colour charge has a anti colour charge.
The anti colour of red, is anti red or cyan.
The anti colour of green , is anti green or magenta.
The anti colour of blue, is yellow.
Spin.
Spin is a property of elementary particles.
The spin is not associated with rotation.
It refers to the angular momentum of the elementary particle.
It is a solely quantum mechanical phenomena.
The spin has only certain quantised values.
The spin is a quantum number,
and a property of an elementary particle.
Protons, neutrons and electrons have a half integer spin.
A half integer spin can be 1 by 2, 3 by 2 etc.
The Pauli's exclusion principle, states that,
no two particles with a spin of 1 by 2,
can share the same quantum states, at the same time.
Spin can be positive are negative, corresponding to spin up, or spin down.
Two particles with a spin up, and spin down can share the same quantum state.
Spin is associated with a corresponding magnetic field.
Quarks.
There are six types or flavours of quarks.
They can be visualised in pairs.
The Up quark and the Down quark:
The charm quark and the strange quark:
The top quark and the bottom quark:
The most common quarks, are the Up quark and the Down quark.
Protons and neutrons are made up of Up quarks and Down quarks.
Quarks can be visualised, as having a weak nuclear force in its centre.
The range of this weak nuclear force, is extremely limited.
The range is limited to a size, smaller than the proton.
The weak force can be involved, in changing a up quark,
to a down quark.
Quarks carry electric charge, and a weak isospin.
Quarks carry a fractional electric charge.
Up quarks have a electric charge of plus 2 by 3.
Down quarks have a electric charge of minus 1 by 3.
This electric charge creates an electromagnetic force.
This electromagnetic force weakens with distance from the quark.
Quarks have a colour charge.
Red, blue, and green are the colours that qualify a quark.
The colour charge is the defining feature of a quark.
The colour charge is associated with a strong nuclear force,
which bind quarks together.
The residual colour charge, binds the protons, and the neutrons,
in the nuclei.
Colour charged particles interact via gluon exchange.
Gluon is a force carrier particle.
Quarks have a spin of 1 by 2.
Quarks travel at close to the speed of light.
Quarks are associated with a strong nuclear interactions.
All elementary particles have a corresponding antiparticle.
The antiparticle of a quark is, called as a antiquark.
Protons.
A proton comprises of three valance quarks.
It is made up of two Up quarks, and one Down quark.
An Up quark has a charge of + 2 by 3.
A Down quark has a charge of minus 1 by 3.
The net charge of a proton is:
+ 2 by 3, + 2 by 3, minus 1 by 3.
This works out to a value of + 1.
This is the net charge of a proton.
Protons and neutrons have 3 particles,
with a spin of 1 by 2.
Protons have 2 up quarks and 1 down quark.
They have a net spin of 1 by 2.
Each quark in the proton has a different colour charge.
The term "colour" has no relationship with visual colour.
The composite of the three colours makes it colourless,
or 0 colour charge.
This principle is called colour confinement.
Gluons are force carriers, which interact with quarks,
and bind them together.
Gluons are also known as the colour force.
They are the equivalent of the electrical force of electrically charged particles.
Inside the proton, gluons are constantly interacting with the quarks.
The gluons are also colour charged.
When a gluon interact with a quark, it changes the colour of the quark.
Due to this quarks are constantly changing colour.
But this change, happens in such a way that the composite colour,
is always white.
This is called colour confinement.
This maintains the integrity of protons.
This is also true for neutrons.
Gluons bind the quarks together, in the proton.
Quarks experience increasing force, when separated.
This helps to bind the quarks together in protons and neutrons.
Gluons have a very strong binding force between quarks.
This force is so strong, that no quark has been detected in isolation.
If a strong enough force is applied to separate the quarks,
in a proton, the quarks decay into,
two pairs of quarks and anti quarks.
Some of the energy expended in trying to separate the quarks,
goes into creating new quarks.
Neutron.
A neutron is made up of 1 Up quark and 2 Down quarks.
The net charge of a neutron is:
+ 2 by 3, minus 1 by 3, minus 1 by 3.
This works out to a value of 0.
This is the net charge of a neutron.
Each quark in the neutron has a different colour charge.
The composite of the three colours makes it colourless,
or 0 colour charge.
This principle is called colour confinement.
Gluons bind the quarks together, in the neutron.
Neutrons have a spin of 1 by 2.
They have a isospin of minus 1 by 2.
Leptons.
The leptons are a group of six particles.
The most familiar lepton particle is the electron.
There are two more heavier and unstable leptons.
They are called as Muon and Tau.
The Electron, the Muon, and Tau are leptons.
The Electron, the Muon, and Tau have a charge of minus one.
Charged particles interact via exchange of photons.
The Electron, the Muon, and Tau, have a associated particle called neutrino.
They are called as:
Electron neutrino.
Muon neutrino and,
Tau neutrino.
This makes a total of six leptons.
Leptons have no colour charge.
Leptons are associated with electroweak forces.
Electron.
The electron is a familiar elementary particle.
In the classical model electrons orbit the nucleus, in different shells.
The electron is a fundamental particle in the standard model also.
The electron in the standard model, is qualified by four quantum numbers.
The quantum numbers helps to better understand, the electron shells in the classical model.
The quantum numbers are compatible, with the quantum model of the electron.
The principal quantum number, is denoted by 'n'.
It takes integer values like 1, 2, 3 etc.
The integer values correspond to the main energy levels.
The second quantum number, is denoted by 'l'.
'l' is the angular momentum quantum number.
'l' can take values, from 0 to n minus 1.
n is the principal quantum number.
The second quantum number, 'l', denotes the shape of the orbital.
In the classical model, the shape of the orbital is always spherical.
In the quantum model, the shape of the orbital differs with each value of 'l', quantum number.
'l' = 0: corresponds to the 's' orbital.
For simplicity, we can visualise, the 's' orbital to be of spherical shape.
'l' = 1 : corresponds to the 'p' orbital.
For simplicity, we can visualise, the 'p' orbital to be of dumb bell shape.
'l' = 2: corresponds to the 'd' orbital.
'l' = 3: corresponds to the 'f' orbital.
The 'd' and 'f' orbitals, have more complex shapes.
The third quantum number, is the magnetic orientation quantum number.
It is denoted by 'm' subscript 'l'.
'm' subscript 'l' can take the values, from minus 'l' to plus 'l'.
Orientation can take the values of 1, 3, 5, 7.
It would be difficult to visualise 5 and 7 orientations,
in 3 dimensions.
We need to think of more dimensions.
The fourth quantum number, is the spin quantum number.
It does not refer to actual rotation.
It is a convenient representation.
An electron has a spin of 1 by 2.
Spin quantum number can take the values,
of plus 1 by 2, and minus 1 by 2.
This is also referred to as spin up and spin down.
According to Pauli's exclusion principle,
no 2 electrons can have the same 4 quantum numbers.
Any particular orbital can have a maximum of 2 electrons,
with opposite spins of plus 1 by 2, and minus 1 by 2.
We can reconstruct the shells and orbitals,
using quantum understanding for atoms,
with different number of electrons.
Electrons are discussed in more detail in,
the Electron module.
Neutrinos.
Neutrinos have no electrical charge.
It is not affected by electromagnetic forces.
It has a very small mass.
It has a weak nuclear charge or force.
The range of this force is very limited, to a size, less than a proton.
Neutrinos can pass through matter, without be detected.
Neutrinos are produced when a quark decays.
A down quark decays, into an up quark, an electron,
and a neutrino.
The nuclear reactions of the sun produces neutrinos.
About 65 billion neutrinos, per square centimeter,
reach the Earth, every second.
It passes through all mass, including our bodies.
But we are totally unaware of it.
Neutrinos eliminate the concept of pure vacuum.
Meson.
A meson has a quark and a antiquark.
Meson's have a integer spin, of 0, 1.
Two particles with a spin of 1 by 2, will have a spin of 1.
They have an electric charge of minus 1, 0 or plus 1.
Forces.
There are four fundamental forces in nature.
Gravity.
Electromagnetic force.
Strong nuclear force.
Weak nuclear force.
These four basic forces, are very different in their intensity.
The strongest force is the strong nuclear force.
This force binds the nuclei together.
The weakest force is gravity.
To get an idea of the magnitude of the forces,
we will consider the strong nuclear force,
to have a magnitude of 1.
In comparison:
The electro magnetic force, has a magnitude of 1 by 100.
The weak nuclear force, has a magnitude of 1 by 100,000.
Gravity has a magnitude of 1 by 10 to the power of 40.
Gravity.
Gravity is the force that holds us, down to Earth.
All objects on Earth are held down, by the force of Earth's gravity.
Gravity is the force, that makes Earth and other planets orbit the sun.
Gravity is the force, which is involved in the stars,
that form our galaxy, the milky way.
Gravity is the force, that is present, through out the universe,
with countless galaxies.
Gravity is the weakest force,
but it pervades the whole universe.
The relationship between gravity, and the fundamental particles,
is still under research.
Electromagnetic force.
The electromagnetic force is considered as a part of the electroweak force.
Light is the most common form of electromagnetic radiation.
Light is a small part of the entire electromagnetic spectrum,
ranging from radio waves to X-rays and gamma rays.
The photon is the force carrier, of all electromagnetic radiation.
We receive light from the sun, and even from the stars.
We also receive other cosmic radiation, which we can detect with instruments.
Electromagnetic radiation, operate over very long distances.
The photon is the universal force carrier particle, of all electromagnetic radiation.
At a macroscopic level, electromagnetism allows particles,
to interact with each other via., electric and magnetic fields.
In the nuclear protons and neutrons exchange photons.
Atoms in molecules are held together by electromagnetic force.
The electromagnetic force, plays a major role,
in determining the internal properties of matter.
Ordinary matter takes its form, as the result of inter molecular forces,
between atoms and molecules, and is a manifestation of the electromagnetic force.
Electrons are bound by the electromagnetic force, to the atomic nuclei.
The electromagnetic force governs the processes involved in chemistry,
which arise from interactions between the electrons, and neighbouring atoms.
The electromagnetic force decreases with increased distance,
between charged particles.
Strong nuclear force.
Protons comprise of two Up quarks and one Down quark.
Neutrons comprise of one Up quark and two Down quarks.
What is the force that holds together these quarks,
in the nuclei of atoms.
Gluons are the binding force, that hold the quarks together,
in protons and neutrons.
Gluons are the force carriers.
They belong to the strongest force, the nuclear strong force.
The strong nuclear force also holds the protons and neutrons together,
in the nuclei of an atom.
Weak nuclear force.
The weak nuclear force, is also referred to as the electroweak force
Weak nuclear forces are responsible for radio active beta decay, and fission.
Weak nuclear forces are involved in the nuclear reactions in stars, like our sun.
The weak nuclear force carriers are bosons.
The W boson has a electromagnetic charge, of +1 or minus 1.
The W minus boson converts a neutron to a proton.
The Z boson has a electromagnetic charge, of 0.
The Z zero boson is involved in changing momentum.
Electroweak force.
The electroweak force, unifies the magnetic and electrical force.
Bosons.
Bosons are force carrier particles.
They mediate interactions among fermions.
They have a integer spin.
For example, they can have a spin of 0, 1, 2.
Gluons, photons, gravitons, are examples of bosons.
Group of bosons gather in the lowest possible energy state.
Bosons do not obey Pauli's exclusion principle.
Bosons can be of two types:
Gauge bosons.
Scalar bosons.
Gauge bosons.
The force fields in electrical and magnetic fields,
are called gauge bosons.
They are the physical reality, and occupy space.
By quantum laws, they appear and disappear quickly.
The gauge bosons are:
Photon.
W and Z bosons.
Gluons.
An hypothetical graviton.
Photons.
Photons are gauge bosons.
The photon is the force carrier, for electromagnetic interactions.
Photons travel at the speed of light.
They cannot come to rest.
Light is one form of electromagnetic radiation.
A photon of light has just enough energy,
to excite a single receptor molecule, in the eye.
It is also involved in weak nuclear forces.
They are responsible for the proton electron interaction.
Whenever charged particles interact,
they exchange photons.
The photon has no mass, no electric charge, no colour charge, no weak charge.
It has the spin of 1.
The electroweak force unifies the electromagnetic and weak nuclear forces.
The photon is the force carrier, in the electroweak force.
QED- Quantum Electrodynamics.
QED or quantum electrodynamics deals with forces associated with the photon.
The photon is associated with electromagnetic forces,
and weak nuclear forces.
The weak electrical force unifies the electromagnetic force,
and the nuclear weak force.
W and Z bosons.
The W boson has two varieties.
The W plus boson, the W minus boson.
The W and Z bosons are associated with the weak nuclear forces.
The W plus, W minus, and Z bosons are 80 to 90 times,
as heavy as a photon.
The forces have a limited range,
which is about one hundredth time, the diameter of a photon.
The W boson causes quarks to change flavour.
Gluons.
Gluons are associated, with the strong nuclear forces.
Gluons are the binding force, that hold the quarks together,
in protons and neutrons.
They belong to the strongest force, the nuclear strong force.
Gluons have no mass, no electric charge, and no weak charge.
Gluons exists only virtually, when two quarks interact.
Gluons can generate other second generation gluons,
ad infinitum.
The strong nuclear force also holds the protons and neutrons together,
in the nuclei of an atom.
Gluons are colour charged force carriers.
The colour charges of gluons comes in nine flavours.
Red-magenta.
Green-cyan.
Blue-cyan.
Red-yellow.
Green-yellow.
Blue-magenta.
Red-cyan.
Green-magenta.
Blue-yellow.
The red-cyan, the green-magenta, and the blue-yellow gluons,
are called colourless gluons,
because they contain a combination of a colour and anti colour.
When a colour gluon interacts with the quark,
it changes the colour of the quark.
When two quarks interact with each other,
both the quarks change colour.
For example, this kind of an interaction are always happening inside protons and neutrons.
But, this happens in such a way, that the composite colour, is always white.
QCD: Quantum chromodynamics.
QCD is concerned with the colour forces.
The colour forces are mediated by gluons.
They are massless.
They have integer spin.
Graviton.
The graviton is a hypothetical particle associated with gravity.
The Higgs boson.
The Higgs field has no source.
It has a value that exists throughout space.
The cosmos is saturated with the Higgs field.
Higgs bosons are the quanta of the Higgs field.
The Higgs boson interacts with all particles,
except the photon, graviton, and gluon.
The Higgs boson is a scalar boson.
They have spin of 0.
The Higgs particle has theorised for many decades.
Its presence was conformed recently,
in the particle accelerator at CERN.
The Higgs particle is responsible for providing mass to other fundamental particles.
The top quark has the highest rest mass.
It has the strongest interaction with the Higgs field.
In contrast a neutrino which is almost massless,
has a very tiny interaction with the Higgs field.
Energy.
The energy of a particle, is proportional to its frequency.
It is given by the formula , E = nhf.
E is the energy of the particle.
n is a integer value.
h is the Planck's constant.
f is the frequency.
The value of the Planck's constant is very small.
It is equal to 6.6 multiplied by 10 to the power of minus 34, joule per second.
It can also be expressed as,
4.136 multiplied by 10 to the power of minus 15 electron volts per second.
Energy of a photon is given by the equation,
E = hf.
De Broglie wavelength.
De Broglie wavelength is denoted by Lambda.
Lambda is equal to h by p.
Lambda is the De Broglie wavelength.
h is the Planck's constant.
p is the momentum.
Standard model : Atom to universe.
The quarks, the leptons, and the bosons, together constitute the standard model.
The standard model along with gravity, describe everything from the atom
to the universe.
Anti matter.
Fundamental particles have corresponding anti particles.
The twelve flavours of fermions, have a corresponding anti fermion particle.
There are twelve fundamental fermionic anti particles.
For example, each quark has a corresponding anti quark.
We know off 6 quarks, the Up, Down, Charm, Strange, Top, Bottom.
Each of them has a corresponding anti quark.
Corresponding to an electron, there is an opposite particle called the positron.
The positron has a charge of plus one.
When a quark collides with an antiquark, they annihilate each other.
We know that mass and energy are interchangeable .
This was elegantly stated by Einstein, in his famous equation,
E= mc squared.
E represents energy.
m represents mass.
c represents the speed of light.
When matter collides with anti matter,
it releases energy proportional to its mass.
Matter in the universe.
The standard model explains all matter in the universe.
This sounds very comforting.
We might be surprised to know, that only 4% of the universe is matter.
73% of the universe comprise of dark energy.
23% of the universe comprise of dark matter.
Only 0.4% of the universe comprise the zillions of stars, in the universe.
3.6% of the universe comprise of inter stellar gas.
The standard model describes this 4% we know as matter.
We know very little of 96% of the universe, appropriately,
called dark energy, and dark matter.