1.2 The Big Bang Flashcards
what is the universe
all of space, time, matter, energy and the physical laws and constant that govern them. It encompasses everything that exists, including all galaxies, stars, planets, moons, asteroids, comets and life
what happens to white light when it enters a glass prism
rainbow spectrum, light refracts
what is the longest wave length
radio waves
what is the shortest wave length
gamma ray
what is the Fraunhofer spectrum
visible light passes through gas/plasma will have dark lines corresponding to particular molecules or atoms of a specific element, useful to study composition and properties of distant objects
what did Edwin Hubble discovery
that there are other galaxies
what is the red shift
the more distant the object, the greater the shift towards the red in the spectral lines, as space expands, it physically stretches wave lengths of the light coming from galaxies
raisin bread expanding, raisin is galaxies, dough is space
what is Hubbles law
redshifts in the spectra of distant galaxies and the apparent speeds they are moving away are proportional to their distance (farther galaxies move away faster)
how fast is the universe expanding today
70.6km/s/mega parsec (one mega parsec away = 70.6km per second)
how old is the universe using Hubbles law
13.77 billion years
sequence of the Big Bang
1) t= 0, universe began 13.8 billion years ago, very dense and hot
2) t = 10 ^ -43, rapid expansion to size of grapefruit, temperature drops to 10^27K
3) t = 10 ^ -12, expansion slows, 4 fundamental forces presentt
4) t= 1 second , university composed of every and fundamental particles such as quarks, electrons, photons and neutrinos, 10^10k
5) t=3 minutes, three light years in diameter, nucleosynthesis occurs, 10^9k
6) t = 380,000 years, universe is around 3000K, cool enough for positively charges atomic nuclei to capture negatively changed electrons, first atoms form (era of recombination), universe is dark (cosmic dark ages)
7) t=400m years, irregularities in gases had collapsed in gravity to form stars and galaxies, light still couldn’t travel very far due to hydrogen fog blocking light
8) T=1b, UV radiation from the first stars ionized hydrogen, universe lights up
9) 13.6b years ago, milky way forms
10) 4.6 billion years ago, solar system forms
11) 200-300 thousand years ago, homo sapiens evolved
what are the four fundamental forces
1) strong nuclear force
2) electromagnetism (100x weaker than snf)
3) weak nuclear force (10,000x weaker than SNF)
4) gravity (10^39x weaker than SNF)
what is nucleosynthesis
neutrons and protons combine to form the first nuclei of H, He and minor LI
what is the significance of quarks in the Big Bang
collide to form protons and neutrons
what is the era of recombination
first atoms form
what is the cosmic dark ages
universe to our eyes would be dark, stars had yet to form
what is the cosmic microwave background radiation
Herman and Alpher prediction that prior to recombination, universe was full of hot energy particles and energy, a plasma
plasma emitted lots of electric magnetic radiation but light could not travel very far
would have cause foggy plasma to glow an orange colour
at recombination, fog clears permitting light (flash) that was emitted just prior to recombination
Alpher and Herman postulated that we should be able to see the flash of light before the universe went dark
what is the significance of the temperature of the CMB
matter not distributed evenly, some matter is marginally denser and hotter (marginally) and higher density areas gravitationally attract matter to become galaxies over time
what is the overall structure of the universe
68% dark energy
27% dark matter
5% visible matter
what is dark matter
unknown material that exerts a gravitational effect
presumably the reason why galaxies do not rotate in the manner predicted, outer edge moving way too fast, outer particles should be flung out into space but they are not
dark matter some sort of particle that holds galaxy together
what is dark energy
acts in the opposite manner of gravity, pulling apart rather than drawing together
cause of universes expanding accelerating
what is it? still dont know
what is the cosmic web
galaxies are arranged in filaments connected by thin, thread-like structures of visible and dark matter.
what are filaments
largest structure in the universe, form boundaries between large voids
what happened to the universe at t=0
1) t= 0, universe began 13.8 billion years ago, very dense and hot
