The Big Bang Flashcards
What was the Big Bang?
An event which birthed the Universe
How would I describe the universe?
Started from a point, known as the singularity, and matter was condensed from the energy that resulted from this. To this day, the universe remains expanding and cooling
Who proved that the universe was expanding?
Edwin Hubble
What were the first fundamental particles formed?
Leptons, neutrinos, and quarks + zero mass particles like gluons and photons
How did the fundamental particles form other particles?
As the temperature decreased, the quarks collided with each other to form hadrons, like protons and neutrons.
What was the force that initially came from the birth of the universe?
The unified force
What was Hubble able to prove?
Able to prove that the further away the galaxy was relative to the Eaerth, the greater velocity of the galaxy
v = Hd
What is cosmic redshift?
Redshift of the wavelengths of radiation due to the expansion of space
What are the differences between cosmic redshift and doppler effect?
Dop. effect depends on relative velocity of source and observer at the time light is emitted
- cosmic redshift occurs after the light has been emitted due to the expansion of space
What is luminosity?
Power emitted by a star - stars are assumed to be black bodies
What is brightness of a star?
Refers to how bright the star appears from Earth - measure of the intensity
Explain the formation of the Big Bang theory.
13.7 billion yrs ago, a singularity expanded, creating space, time, energy and matter. The Big Bang was the birth of the universe at the beginning of time.
#1 = expansion and cooling
#2 = gravity
What was the first phase of evolution?
Expansion led to cooling as the energy of the universe was spread - allowed energy to be converted into matter - formed quarks, leptons - decayed to form protons, neutrons and electrons
What was the second phase of evolution?
Gravity led to the gas in the universe collapsing into giant clouds and eventually forming the stars and galaxies we see today
Explain the process of the universe
- inflation
- post inflation - expanding and cooling at a slower rate
- nucleosynthesis = protons & neutrons form helium
- recombination = further cooling to form neutral atoms
- reionisation = first stars form
What are the three main pieces of evidence to support Big Bang Theory?
- Expansion of universe
- Abundance of light elements
- Cosmic microwave radiation in background
How did abundance of light elements prove the existence of the universe?
Energy –> matter —> p, n, e-
At high temp, hydrogen -> fusion –> He –> formation of light elements = nucleosynthesis
How does cosmic radiation prove big bang?
Universe filled with charged particles (q, L)
- absorb and emit radiation
- radiation (photons) coupled to matter
- radiation and matter were in equilibrium
then recomb, the radiation recoupled from matter - nuclei formed neutral gas - universe became transparent
- radiation was not interacting with matter
How does gravity prove big bang?
Universe was filled with neutral gas - as gas cooled kinetic energy, the gravitational forces show that there is an uneven distribution of matter
- links to accretion
What is accretion?
Process by which denser objects attract matter due to their gravity
- variations in strength - mass is pulled by denser regions - stronger gravity - uneven distribution of clouds
What is up the top on the hertzsprung russel diagram?
Supergiants, then giants, then main sequences, and bottom white dwarfs
What is the stellar evolution?
Mass - determine their position, evolution, process inside the star, etc.
Summarise the formation of a star
- Cold giant cloud –> undergoes accretion
- PE => KE
- Temp increases, radiation emits - forming protostar
- Further collapse leads to high temp, hydrogen fusion, collapse continues, fusion releases energy resulting in radiation pressure
The mass determines whether the star sits in the main sequence
High mass will be larger so higher temp as they collapse, meaning the rate of fusion is higher leading to higher luminosity
