Big Bang lecture 7 Flashcards
What did Lemaitre propose?
That universal expansion can be traced back to a single point = the big bang (AKA the primeval atom)
What is the balloon model?
As the balloon inflates, the wave length of light gets stretched out (increases)
What is Hubble’s law?
As the distance increases, as does redshift which confirmed existence of cosmic expansion
what is the oscillating universe theory?
An explanation to the red shift observations - Einstein considered a cyclic universe which begins with a BB and ends in the Big Crunch with the cycles getting longer and larger. However it doesn’t replace the BBT
What is the tired light theory?
Was proposed by Zwicky to explain the red shift observations - as light travels through vast distances, it slowly loses energy when it interacts with matte radn other light waves therefore WL increases as distance does. But is not supported by observational tests as images would appear scattered and blurry
who rejected the BBT and what was suggested in its stead?
Hoyle rejected it and proposed the steady state theory = the universe is eternal and unchanging but the galaxies drift away, however new galaxies would be created therefore the density will remain the same
What is the creation field?
the explanation for the continuous creation of matter which is the energy that drives expansion of the universe - cosmic inflation
what is the perfect cosmological principle?
That density in the steady state theory is unchanging, the universe is isotropic and homogenous which is an extension of the cosmological principle
What is nucleosynthesis?
proposed by Hoyle - the creation of atoms from existing protons and neutrons adn as Mr increases,
What is stellar nucleosynthesis?
Nuclear fusion reactions that forms atoms - the energy release fuels stars due to difference between reactants and products - 2 or more atoms combine to form one or more different nuclei
Who proposed the hot BB and what is it?
Gamow - shortly after the BB, the universe was hot adn density was high
What is BB nucleosynthesis?
Gamow - the high density and temperature allowed protons and neutrons to combine forming heavier nuclei e.g. deutron - explained in the alpha, beta and gamma paper
what theories are needed to explain the elemental abundances of the universe?
Hoyle’s stellar nucleosynthesis and Gamow’s BB nucleosynthesis
Describe the timeline of the BB
protons and neutrons were created in the BB, then BB nucelosynthesis occurred. 20 mins later it cooled to a point that BBN had ended
