unit 8 physics

cosmic microwaves background radiation

• all directions of space, around -270c

• universe first emitted short wavelength, as universe expanded, stretched to become microwaves,

life cycle of stars

• dust and gas clouds present in universe, form stars, nebula

• gravitational attraction between particles draw them together, form protostar

• cloud becomes more concentrated, as particles get closer, so temp and pressure increase

• pressure higher enough, particles Abel to fuse together,

• fusion occurs, hydrogen nuclei fuse to form helium nclei

• creates a large amount of energy

• outwards pressure causes b fusion balances the force of gravity inwards, equilibrium

small stars

• swells into red giant

• unstable, ejects outer layer of dust and gas

• leaves behind hot, dense solid core, white dwarf

• cools down, emits less energy, no longer emits a signicaint amount, black dwarf

larger stars

• hydrogen runs iut

• swells into red super giant, becomes red as the surface cools

• fusion of helium, increasing pressure and temps means heavier element can fuse

• once all fusion happens, to massive to be stable, star collapses and rebounds on its centre, explodes into supernova,

• ejecting heavier elements to form new stars and planets

• exploding supernova throws outer layer o dust an d gas into space

• leaving hot dense core, neutron star or black hole

red shift

• increase in wavelength of light from most distant galaxies

• further away galaxy, faster they are moving and the bigger the red shift

• observations of supernova since 1988, suggest that distant galaxies re reeding her faster