Lesson 4 - the Big Bang and the Expanding Universe

Birth and Early Life

Low mass: from small/medium portion of nebula, turns into a hot dense clump and starts producing energy

Intermediate: from large portion of nebula, turns into hot dense clump and starts producing large amounts of energy

High: from very large portion of nebula, ““

Main Sequence Phase

Longest phase

Low: nuclear fusion is 10 - 100 billion of years

Intermediate: produces energy for a few million years, burns brighter (1000s times brighter than sun)

High: nuclear fusion produces E for a few million years, extremely bright

Old Age

Low: Uses up fuel, swells to become large, cool, red giant

Intermediate: uses up fuel, swells, becomes red supergiant

High: uses up fuel, swells becomes red super giants (large than intermediate)

Death

Low: outer layers of gas drift away, core shrinks becomes a small hot dense white dwarf

Intermediate: core collapses, outer layers explodes in supernova

High: core collapses, outer layers explode as huge supernova

Remains

Low: white dwarf cools and fades

Intermediate: core packs together —> neutron star, gases drift off as a nebula

Remains: core packs together —> black hole, gases drift off as a nebula

Time life of a star

5 - 100 billion years, more massive stars burn hotter and faster so they have shorter life spans

The death of a star

nuclear fusion comes to an end when fuel is exhausted, leading to stable elements, ends with iron (nickel) and the outer layers cause an explosion called a supernova

supernova causes protons and electrons to form neutrons, resulting in either a neutron star or black hole

iron group elements can then capture these neurons to form heavy metals (gold, silver)

Neutron star

densest objects in the universe, strongest magnetic fields, vortexes at the poles of the neutron stars seen as beams of light rotating with the neutron star called pulsars, 700 rotations per second and they are formed from the remnants of massive stars after a supernova.

Two types of black holes

Stellar (around the galaxy, radius of ~300km, moves) and Super Massive Black holes (centre of galaxy, stands billions of km)

Singularity

theoretical point at the very centre of the black hole where matter is crushed to infinite density

Event Horizon

Boundary where the velocity needed to escape the black hole is the speed of light

Event horizon Shadow

Dark zone twice as big as the event horizon

Photon spheres

rings of light appearing at the edge of the event horizon shadow

Relativistic/ particle jets

streams of matter moving away from the black hole at nearly the speed of light

Accretion Disc

hot disk of gas orbiting the black hole and its main source of light

Big Bang Theory

formed around 13.8 billion years where a sudden rapid expansion in an event gave a rise to energy and matter, started as a small dense hot ball and expanded rapidly, cooling allows for subatomic particles to come together as atoms

Cosmic Background Radiation

energy transmitted in waves is observed in every part of space, remains of radiation from the Big Bang event

Expanding universe

doppler effect where waves moving towards you are compressed, moving away are spread out

Doppler Effect with light waves

star is moving towards you, its wavelengths are compressed, blue shift

star is moving away from you, red shift and its wavelengths get longer and stretched, shifted to the red