Physical Science

• The Big Bang Theory states that the universe continues to move and expand.
• The Big Bang Theory is a cosmological model that describes how the universe started its expansion about 13.8 billion years ago
• The Big Bang Theory states that the universe began as a singularity or a point containing all space, time, matter, and energy
• The Big Bang Theory expanded rapidly in nothingness through a rapid yet peaceful process called inflation and the universe cooled down as it expanded
• In the Big Bang Theory, a soup of matter in the form of subatomic particles was formed and nuclei of light atoms were created via

  nucleosynthesis or nuclear fusion between protons and neutrons.
• In the Big Bang Theory, Electrons interacted with these nuclei to form actual, primordial atoms via the process of recombination.
• In 1927, Georges Lemaitre proposed the alternative idea that the universe is expanding
• In 1929, Edwin Hubble calculated distances between the earth and several galaxies using redshift of light
• In 1929, Edwin Hubble observed distant galaxies were moving away from the Earth and one another
• In 1965, Robert Wilson and Arno Penzias Discovered cosmic microwave background radiation (CMBR)— a low, steady humming noise

  believed to be energy remains from the Big Bang
• In 2014, The Universe is estimated to be 13.8 billion years old with

  5% of its composition exists as ordinary matter
• Big bang nucleosynthesis (BBN), also known as primordial nucleosynthesis is the process of producing the light elements during the big bang expansion
• Big bang nucleosynthesis yields two stable isotopes of hydrogen, two isotopes of helium, some lithium atoms, and beryllium isotopes
• To verify the observations of the Big Bang Theory, scientists

  measured abundances of primordial material in unprocessed gas in some parts of the universe with no stars, as well as in parts of meteorites known as chondrites that commonly fall to Earth.
• A proton (p) and a neutron (n) may fuse together to yield a

  high-energy photon (γ) and an isotope of hydrogen (H)

  called deuterium (D or 2H, with one p and one n).
• The deuterium bottleneck can be traced to its low binding energy

  and eventual destruction by photons at very high temperatures.
• A decrease in temperature enabled deuterium to stabilize and

  eventually, initiate the BBN cascade.
• Two D nuclei may fuse together to form either of the

  following:The radioactive H isotope tritium (T or 3H, with one p and two n) and one p; or

  b. The isotope helium-3 (He-3 or 3He, with two p and one n) along with

  one n
• Helium-4 (He-4 or 4He, with two p and two n) may be formed

  from three fusion reactions: a. The fusion of one p and a T atom b. The fusion of D with T and c. The fusion of D with He-3
• He-4 has a binding energy of 28 MeV. Further fusion

  products were a rarity since these resulting atoms had

  binding energies lower than this amount mentioned above.
• He-4 may still undergo further fusion in the presence of

  a T atom, yielding the lithium-7 atom (Li-7 or 7Li, with

  three p and four n) and a γ.
• Li-7 may react with one p to produce two stable He-4 nuclei.
• He-4 may also fuse with He-3 to yield the unstable

  isotope beryllium-7 (Be-7 or 7Be, with four p and three n)

  along with one γ.
• The correlation between predicted and observed cosmic

  abundances of H and He was the major proof of the big

  bang theory.
• Almost all available neutrons have combined with protons, forming 24% He-4 by mass.
• About 74% H by mass remained uncombined in the Big Bang
• To verify these observations, scientists measured abundances of primordial material in unprocessed gas in some parts of the universe with no stars, as well as in parts of meteorites known as chondrites

  that commonly fall to Earth.
• Stellar nucleosynthesis is a process by which element are formed within the stars as a result of nuclear fusion
• The sun is believed to be in the middle of the main sequence phase of stellar evolution
• Protostars evolve into main sequence stars upon reaching gravitation equilibrium
• Main sequence stars evolve into red giant stars when all hydrogen atoms in their cores get depleted.
• Triple alpha process involves the fusion of three helium-4 nuclei (alpha particles) to form a carbon-12 nucleus.
• Nuclear fusion is the process by which multiple nuclei joined together to form a heavier nucleus
• Two helium-4 nuclei (alpha particles) fuse to form a beryllium-8 nucleus.
• Carbon Fusion Cycle or CNO Cycle is a process where C-12 is used as a catalyst that facilitate the production of He-4
• A third helium-4 nucleus collides with the beryllium-8 nucleus, forming a highly excited state of carbon-12.
• Alpha ladder refers to a series of nuclear reactions involving the sequential addition of helium-4 nuclei (also known as alpha particles) to form heavier elements.
• Plasma soup was where nuclei of light atoms started to form via nucleosynthesis or nuclear fission between protons and neutrons.
• The American cosmologist Ralph Alpher was able to prove BBN with his calculations. He calculated the proportions of neutrons and protons present in the early universe when the big bang started. With the right knowledge of these proportions and the energy present in the early universe, he predicted that elements such as hydrogen and helium could be formed.
• Binding energy is the energy required to break down a nucleus into its components.