The Formation of the Universe Flashcards
How old is the universe?
13797 million years
What event does the Big Bang theory describe?
A cosmic explosion of the previously existing singularity
What is the evidence that the universe is expanding?
The red-shift theory proves this as galaxies further away appear more red, as their wavelength is increasing size (think Doppler effect)
Why has the universe cooled as it expanded?
The kinetic energy of particles decreases as they travel longer distances and there is less collisions. The average energy density decreased, meaning that temperature decreased.
How has the rate of expansion changed since the Big Bang?
The rate of expansion increased rapidly at the beginning of the grand unification epoch, since then it stabilised and the rate of expansion steadily increases to this day.
What is astronomical redshift, and how is it different to the doppler effect?
Astronomical red shift is the extension of EM wavelengths due to the expansion of space (making the light appear more red). The Doppler effect is the extension of EM wavelenghts due to the movement of a source relative to the observer.
What is Hubble’s Law?
Describes the observation that the universe is expanding, with galaxies moving away from each other. More specifically, it states that the velocity at which a galaxy is receding from an observer is directly proportional to its distance from the observer.
What is Hubble’s constant and how is it measured?
Current values estimated 70km/s/Mpc. It is calculated by measuring the recessional velocity and distance of a galaxy or an object (velocity divided by distance)
What sequence of key events occurred in the first 380 kys after the Big Bang in the history of the Universe?
Planck, Grand Unification, Electroweak, Quark, Hadron, Lepton and Photon epochs, then the cosmic dark ages.
What are the four fundamental forces?
Strong, weak, gravitational and electromagnetic forces
What energy field is responsible for particles having mass? How does it confer mass?
Higgs field permeated the universe during the quark epoch, Higgs bosons confer mass onto other particles by contact, this causes the particles to slow as they are resisted.
In which era did the first normal matter form?
Hadron epoch
What elements were formed through primordial nucleosynthesis during the photon epoch before the universe cooled too much?
Hydrogen, deuterium, helium-3, helium-4 and limited amounts of lithium
What is recombination and how did it effect the ‘transparency’ of the universe?
The capture of electrons by atomic nuclei in the plasma of the photon epoch caused the gamma rays and photons to escape the plasma, causing the universe to become transparent.
Why was the era known as the ‘dark ages’ dark?
Atoms and light make up <5% of the universe at this point, it is dominated by dark energy and dark matter
