The Big Bang and The Standard Model

/ Timeline of the metric expansion of space /


The Big Bang theory is the prevailing cosmological model for the observable universe from the it’s earliest known periods through its subsequent large-scale evolution. The model describes how the universe expanded from a very high-density and high-temperature state and offers a comprehensive explanation for a broad range of phenomena, including the abundance of light elements, the cosmic microwave background (CMB), large-scale structure and Hubble’s law – the farther away galaxies are, the faster they are moving away from Earth. If the observed conditions are extrapolated backwards in time using the known laws of physics, the prediction is that just before a period of very high density there was a singularity which is typically associated with the Big Bang.

Current knowledge is insufficient to determine if the singularity was primordial.



The Theory of a Big Bang

Electron – Quarks – Neutron – Proton – Hydrogen nucleus – Helium nucleus – Hydrogen atom – Helium atom – Protogalaxy – Galaxy



Time: 10-43 seconds


In this first phase of Creation the cosmos goes through a superfast ”inflation”, expanding from the size of an atom to that of a grapefruit in a tiny fraction of a second.


Time: 10-32 seconds

Temperature: 1027 °C

In this first post-inflation period the universe is a seething hot soup of electrons, quarks and other particles.


Time: 10-6 seconds

Temperature: 1013 °C

A rapidly cooling cosmos permits quarks to clumps into protons and neutrons.



Time: 3 minutes

Temperature: 108 °C

Still too hot to form into atoms, charged electrons and photons prevent light from shining: the universke is a superhot fog.


Time: 300.000 years

Temperature: 10.000 °C

Electrons combine with protons to form atoms, mostly hydrogen and helium. Light can finaly shine now.


Time: 1 billion years

Temperature: -200 °C

Gravity makes hydrogen and helium gas coalesce to form the giant clouds taht will become galaxies; smaller clumps of gas collapse to form the first stars.



Time: 15+- billion years

Temperature: -270 °C

As galaxies cluster together under gravity, the first stars die and spew heavy elements into space: these will eventually form into new stars and planet.



The Standard Model of

Fundamental Particles and Interactions

The Standard Model summarizes the current knowledge in Particle Physics. It is the quantum theory that includes the theory of strong interactions (Quantum chromodynamics or QCD) and the unified theory of weak and electromagnetic interactions (electroweak). Gravity is included here because it is one of the fundamental interactions even though not part of the ”Standard Model”.



Matter Constituents
Spin = 1/2, 3/2, 5/2, …

In particle physics, a fermion is a particle that follows Fermi–Dirac statistics. These particles obey the Pauli exclusion principle. Fermions include all quarks and leptons, as well as all composite particles made of an odd number of these, such as all baryons and many atoms and nuclei. Fermions differ from bosons, which obey Bose–Einstein statistics.

A fermion can be an elementary particle, such as the electron, or it can be a composite particle, such as the proton. According to the spin-statistics theorem in any reasonable relativistic quantum field theory, particles with integer spin are bosons, while particles with half-integer spin are fermions.


Flavor – Mass GeV/c2 – Electric charge
electron neutrino<1 x 10-8; 0
electron; 0.000511-1
muon neutrino
tau neutrino
1.7771; -1


Flavor – Mass GeV/c2 – Electric charge
up; 0.003; 2/3
down; 0.006; -1/3
; 1.3; 2/3
; 0.1; -1/3
; 175; 2/3
; 4.3; -1/3



Force carriers
Spin = 0, 1, 2, …

In quantum mechanics, a boson is a particle that follows Bose–Einstein statistics. The name boson was coined by Paul Dirac to commemorate the contribution of Indian physicist and professor of physics at University of Calcutta and at University of Dhaka, Satyendra Nath Bose in developing, with Albert Einstein, Bose–Einstein statistics – which theorizes the characteristics of elementary particles.

An important characteristic of bosons is that their statistics do not restrict the number of them that occupy the same quantum state. This property is exemplified by helium-4 when it is cooled to become a superfluid.

Unified Electroweak spin = 1

Name – Mass GeV/c2 – Electric charge
photon; 0; 0
W; 80.4-1
W+; 80.4+1
Z0; 91.1870

Strong (color) spin = 1

Name – Mass GeV/c2 – Electric charge
gluon; 0; 0
Each quark carries one of three types of  ”strong charge”, also called ”color charge” and these charges have
nothing to do with colors of visible light. 


One cannot isolate quarks and gluons; they are confined in color-neutral particles called hadrons. This confinement (binding) results from multiple exchanges of gluons among the color-charged constituents. As color-charged particles (quarks and gluons) move apart, the energy in the color-force field between them increases. This energy eventually is converted into additional quark-antiquark pairs. The quarks and antiquarks then combine into hadrons; these are the particles seen to emerge. Two types of hadrons gave been observed in nature: mesons and baryons.

The strong  binding of color-neutral protons and neutrons to form nuclei is due to residual strong interactions between their color-charged constituents. It is similiar to the residual electrical interactions that binds electrically neutral atoms to form molecules. It can also be viewed as the exchange of mesons between the hadrons.

Baryons and Antibaryons

Symbol – Name – Quark content – Electric charge – Mass GeV/c2 – Spin
p; proton; uud; 1; 0.938; 1/2
p; anti-proton;u-u-d-; -1; 0.938; 1/2
n; neutron; udd; 0; 0.940; 1/2
; lamda; uds; 0; 0.116; 1/2
; omega; sss; -1; 0.672; 3/2


Symbol – Name – Quark content – Electric charge – Mass GeV/c2 – Spin
π+; pion; ud-; +1; 0.140; 0
K; kaon;su-; -1; 0.494; 0
ρ+; rho; ud-; +1; 0.770; 1
B0; B-zero; db-; 0; 5.279; 0
; eta-c; cc-; 0; 2.980; 0




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