Howard Toh (S1-04) (26)

9/3/2022: Part 1/3 (the beginning)

Theory of everything:

General Relativity of Quantum Theory

Special Relativity

Schrodinger solution

Hawking Radiation

Definition of gravitational field:

Field by bouncing a photon of it

Use X-Rays

Epochs

Planch Epochs

Gravity behaves according to Quantum Mechanics and the law of physics

Gravity Unification Epoch

Gravity ‘left’ from the four forces

-Strong Nuclear force

-Weak Nuclear force (Radioactive decay)

-Electromagnetic force

Other Epochs

Space became large by 10^26

This resulted in the three forces becoming what they are today.

Quarks = Sub-Sub atomic

Temp. Drop, Hadrons started

Hadrons = Protons/Electrons

Protons and Neutrons fuse to become nuclei

Recombination Epoch

CMBR originates here

After the Dark Ages

Universe became transparent

Gravity pulled compact clouds of hydrogen together to form the first stars!

These classified as Population III Stars

No metals, Size is between a few hundred to 1000 solar masses

Extremely luminous

Birth of Galaxies

The birth of stars accelerated after the Dark Ages

Denser clumps of matter came together

Protostars came close to each other and formed protogalaxies

Galaxies Mergers

Galaxies merged together due to gravity (became more elliptical)

Galaxies became Galaxy clusters

Formed some black holes due to gravity

Start of the Solar System

Sun + planets formed 4.6 billion years ago

Sun formed in the centre

Sun booted up and ignited, blowing the gas away

Planetesimals were formed from small bits of dust and gas dumped together

Planetesimals then collided with each other to form planets

Terrestrial planets formed closer to the Sun, Jovian Planets formed further to the Sun

Cooling Down

Collisions and debris rain down on larger objects.

Amount of stray decreased, heat generated reduced

Starting Afresh

Orbits have been swept clean of debris

Smaller planetesimals who failed to become planets were captured by planets and became moons (except Earth)

Birth of our Moon

Moon formed when a Mars-sized body, Thea, collided with Earth, causing a large amount of debris that became a moon

Initially molten, cooled over time

Birth of Black Holes

Types of Black Holes:

Stellar black holes: Formed by the collapse of stars

Supermassive black hole: Millions of solar masses heavy

(theory) Primordial

-Stellar Black Holes

Formed if a neutron star caused by a type II supernova absorbs enough material from a nearby star

Must be greater than 5 solar masses* for the escape velocity to be greater than the speed of light

Stars must be greater than 20 Solar Masses for this to happen

-Supermassive Black Holes

1. Clouds of gas were dense and became BH

2. Formed during early years

3. Rapid formation of galaxies in the early ages

Part 2/3 (the beginning of the end)

Death of a star

Low-mass stars are very small, compared to red dwarves

Fuse hydrogen to helium very slowly

Nuclear Fusion

When different molecules collide with each other and produce an immense amount of energy in the process

Stars with less than 25% of solar masses will NOT form red giants\

They will form white dwarves in TRILLIONS of years

Above and they WILL expand into a red giant

Intermediate Mass Stars

Heavier, but not heavy enough to explode

Will form red giants

Capable of fusing helium into Carbon and Oxygen (amongst others)

White Dwarfs

Remains of Low to Intermediate Mass Stars

Extremely dense and have the mass of the sun with the volume of the Earth

High Mass Stars

10 to 70 Solar Masses

Can explode in Supernovas

Can turn into different bodies

Supernovas

Cores of stars are usually obliterated so white dwarves are unlikely to appear

Shockwaves. It explodes as it collapses itself very very fast and that creates a MASSIVE shockwave

Above is Type II Supernova

Type I Supernova

(Going through Type 1A only, lol)

This involves 1 white dwarf and 1 BIGGER star

The white dwarf accumulates matter until it explodes

(Same for 2 white dwarves colliding)

Neutron Stars

When a star collapses on itself, atoms in the core are compressed into neutrons

Stars can spin very fast and become either a Pulsar or a Magnetar

Pulsar

Emits significant amounts of intense energy at intervals

Emits a powerful magnetic field

Magnetar

The magnetic field is 1000s of times stronger than the neutron star’s

Movement in the crust creates a vast amount of energy

Black Holes (Part 2)

When a star collapses, an imaginary surface called the Event Horizon forms

This is the point where even light cannot escape

Higher density = Stronger Gravitational Field

Under TOR, time slows down under the effects of gravity

A point called the point of Singularity is at the centre of the black hole (Hypothesized)

Part 3/3 (the end)

The Death of the Solar System

The inner planets will be vapourised

Proton Decay

A hypothetical form of decay

(Hypothetical as it is not been observed to do so)

Death of Black Holes

Black holes survive by pulling objects into the black hole

When space becomes so vast, the Black Holes cannot 'consume' matter and die due to Hawking Radiation

30/3/2022: A black hole is a place where gravity is so strong that light can't get out of it. We cant see black holes. Observed by its effects on its surroundings. Can be as small as an atom or so big it's as big as a few million Earths. 4 types = stellar-mass, intermediate, supermassive, miniature. Intermediates are bigger than a stellar black hole and 100 to a million times bigger than the sun. Supermassives are the biggest. Miniatures are very small equal to or above 22.1 milligrams. Black holes are created from supernovas. The theory is that the stellar black holes attract each other to make intermediate. the formation of the supermassive black holes are unknown. miniature black holes formed soon after the creation of the universe. The event horizon of the black hole makes it 4000x better than the Hubble space telescope. Very long baseline interferometry uses smaller telescopes to focus on one object. 6 main parts of the black holes. Event horizon the matter inside it would fall to the centre and squishes to one point. the singularity has infinity. a singularity is found in the centre of the black hole and if anything goes inside will experience spaghettification. white holes are the complete opposite of a white hole. Also has a point of singularity but nothing can enter the white holes event horizon. As a black hole and white hole exist in separate places in space a wormhole would bridge the 2 ends. A wormhole is super unstable if a particle dropped to the event horizon of a white hole it would never reach. The only way would be to cross the event horizon of the black hole but once an object crossed the event horizon it would never leave. A wormhole entrance would look like a sphere, if looked into you would see light coming from the other side and distorted views of the region of the universe came from and travelling to. A wormhole could act like a time machine and a wormhole moving at the speed of light would move slower than the wormhole standing still. hawking radiation continuously is emitted by black holes.

6/4/2022: Exoplanets are planets outside our solar system and they orbit around their own stars and form their own solar system. Exoplanets are rogue planets. A habitable zone is where the area around the star is not too cold or not too hot and enough for life to exist. Kepler-186f was the first rocky planet to be found in the Goldilocks zone. Osiris is the first planet to be seen in transit. 51 pegasi b is the first confirmed exoplanet and orbits its star every 4 days, and is half the mass of Jupiter. Kepler 444 is the oldest known planetary system which has 5 terrestrial-sized planets. Kepler 22b is a possible water world planet. Kepler 452b is the first earth-sized planet found in the habitable zone of a sun-like star. Carl Sagan was an American astronomer, and his best-known research was on extraterrestrial life. The first exoplanet was discovered in 1992 but didn't take the form they anticipated and was discovered using pulsars. 97% of the exoplanets confirmed have been discovered by indirect means of discovery. Doppler spectroscopy is one way to find exoplanets. The barycentre is usually closest to the planet with the most mass. If a star has planets the star orbits around the barycentre. Since the mass of a star is mostly significantly more significant than that of the planet the centre of mass of the system usually lies within the stars. Pulsars are rotating neutron stars observed to have pulses of radiation at very regular intervals that typically range from milliseconds to seconds. The orbit parameters can be determined, and exoplanets can be detected but pulsars are relatively rare. Parent stars are usually brighter than the planet, so the light will most likely block the light. the technique which is in general relativity where the light from a star can be bent by the gravity of an object between earth and the source star. The limitations are then this technique relies on chance alignment. Astrometry involves measuring a star's position in the sky accurately and detecting how the position changes over time since a star with a planet will orbit around the common barycentre of the system, the star's position can be used to find the exoplanet.

20 April notes: Rovers are exploration devices and are autonomous. They are used for geological exploration. They study the composition of rock and soil to find evidence that water was on Mars and the environment before. they are lander spacecraft. Ways of landing are to use parachutes, Fire small rockets before impact use sensors to have a controlled landing. Deploy airbags to cushion. Signals from rovers take minutes to reach earth. Signals from rovers take minutes to reach earth. Rovers have various appendages to aid them in the mission. Used as a mast for the sensors to give the rover a human-scale view. Hands to hold rock samples. Drills to study fresh unearthed rock samples. They use solar and nuclear power. Signals from rovers take minutes to reach earth. Rovers have various appendages to aid them in the mission. Used as a mast for the sensors to give the rover a human-scale view. Hands to hold rock samples. Drills to study fresh unearthed rock samples. They use solar and nuclear power. Nuclear-powered ones use plutonium. The Mars Moxie is a special rover part that is used to produce oxygen from carbon dioxide from Mars's atmosphere. The Rock Abrasion Tool (RAT) is used to break open rocks which characterises the bond spectrum of radiation environment found inside the spacecraft during the cruise phase and while on Mars. Spirit died and was completely useless. Perseverance was fully powered by nuclear energy. Opportunity was powered by rechargeable lithium batteries with rechargeable batteries in combination with solar cells. Curiosity used both solar and nuclear energy and has 4 pairs of navigation cameras called Hazcams. Made ingenuity to see if it can fly on mars due to the different atmosphere. The 7 mins of terror are the 7 mins from the rover entering Mars's atmosphere to touching down on the surfaces. All done automatically, people in NASA are in a panic. During a mission, Opportunity encountered hematite, a mineral formed in water suggesting there was water. Spirit found a place on mars with rocks rich in minerals. Opportunity also found bright coloured veins of gypsum in the rocks which scientists believe were there due to flowing water.

4 May) Satellites can be used for different purposes. Commercial and non-commercial. Satellites are used for navigation. Used as telescopes. The International Space Station is used to research the effects of space on the human body. Antennas are used for satellites to communicate with the Earth's ground. ISS is made by 5 countries U.S.A, Russia, Japan, Europe, and Canada. New Horizons is a satellite made by NASA to observe pluto. Sputnik is a satellite made by the soviet union for communication. SMAP satellite is used to detect soil moisture by a golden web. Cassini-Huygens launched into the surface of Titan to take pictures. The ones that don't orbit earth have to go on a different trajectory.