Notes

CCA Notes

Universe Timeline

1)    At the start of the universe,

- There are four forces: Strong nuclear force, weak nuclear force, electromagnetic force, and gravitational force.

- Space became larger by an order of 10^26, over a time of 10^-36 to 10^-32 seconds, cooling the universe by a lot.

- Lastly, the universe became cool enough for electrons, protons, and neutrons to form.

2)    After the dark ages,

- The universe becomes transparent, allowing light to travel long distances.

- Over time, gravity piled the densest regions of hydrogen gas into compact clouds, which then collapsed to form the first stars.

- The birth of stars accelerated as the universe left the dark ages.

- Gravity eventually caused galaxies to merge, forming larger galaxies, Most of the early large galaxies were spirals, but merging caused them to become more elliptical.

- As cooling down happened, many collisions happened as debris rained down on larger objects, causing a lot of heat.

- The amount of stray debris is reduced by various means, decreasing heat generated.

- Then, the planets started cooling down.

- The moon likely formed after a Mars-sized body, Thea, collided with earth several billion years ago.

3)    Types of black holes,

- Stellar Black Holes-Formed by the collapse of stars

- Supermassive Black Holes-Black holes with millions of solar masses, caused by the merging of black holes, absorbing other matter and objects

- Primordial Black Holes-Small black holes that might have been created during the Big Bang.

4)    Stars,

- Nuclear fusion:

a)     The process when two different molecules collide with intense forces to the point when they fuse together, releasing massive amounts of energy.

- Supernovas:

b)    A White Dwarf rotating around another star, leading to the White Dwarf exploding.

5)    Black holes,

- Anything past the event horizon is unknown.

6)    The last fall,

- When the star explodes, planets around it will get vaporised.

7)    Death of the universe,

- When the universe's expansion eventually reverses and the universe re-collapses, it ultimately causes the cosmic scale factor to be zero.

- Everything will break down into smaller substances till everything is gone.

Black Holes

1)    Black holes are created by stellar mass:

- When stars collapse, it creates a supernova, an exploding star that blasts part of it into Space.

- Intermediate black holes are created by 

- Supermassive Blackholes formation is still unconfirmed, but some have suggested that they form from the collapse of massive gas clouds during the galaxy's formation.

2)    How to photograph black holes:

- Event horizon telescope: It captures an image of a black hole 4000 times better than the bubble space telescope.

- Very Long Baseline Interferometry: It creates an array of smaller telescopes that synchronise to capture the same object simultaneously, acting like a giant virtual telescope.

3)    Blackhole parts:

- 6 Main Parts with two extras.

4)    Event horizon and singularity:

- Event horizon is known as the point of no return.

- Once matter falls into it, it will fall to the singularity (centre). Which such strong gravity, any matter is squished to a point, a tiny volume with a large density.

- Singularity is the point of the centre of the black hole. It is very small, so it has essentially an infinite density, which makes it likely that the laws of physics break down at this point.

5)    Any object that falls in a black hole stretches. This process is called spaghettification.

6)    White holes:

- It is the opposite of black holes.

- The black hole will immediately push out anything in it, and nothing can enter the event horizon of the white hole.

- It also has a singularity.

7)    How are white and black holes connected?

- They are connected by wormholes, which bridges black holes and white holes.

- A wormhole is something that connects two distant points in Space.

8)    Hypothetically, wormholes look like a sphere with you being in it, you will see distorted views of the regions of the universe you came from and where you were travelling to.

- Wormholes may also be able to be used for time travel.

- There are eight parts of a black hole and two versions of it, connected by a wormhole (possibly).

Exoplanets

1)    What are exoplanets:

- Exoplanets refer to planets outside our solar systems.

- They orbit their own stars, forming their own solar system.

- Most orbit other stars, but there are free-floating exoplanets, called rogued planets, which orbit the galaxy centre.

2)    Goldilocks Zone:

- Area around the star which is not too hot or cold for liquid water to exist on the surface of the planets.

3)    Examples of exoplanets

- Kepler-186F:

a)     It is an example of an Earth-like planet in the habitable zone.

- 51 Pegasi:

a)     -It is the first planet found so close to its sun that it is almost as hot as the star.

- Kepler-444 System:

a)     It is the oldest known planetary system with five terrestrial-sized planets.

8)    Carl Sagon

- His best-known scientific contribution is his research on extraterrestrial life.

9)    Centre of gravity in Space:

- It is between the gravitational pull between a planet and star, and the planet with the heavier mass will have the centre of gravity nearer to them.

10) Pulsars

- Pulsars are rotating neutron stars observed to have a pulse of radiation at regular intervals that typically range from milliseconds to seconds. 

- Pulsars have powerful magnetic fields that funnel particles' jets out along the two magnetic poles. These accelerated particles produce very powerful beams of light.

- By tracking the motion of pulsars, the orbit parameters can be determined and exoplanets can be detected. 

- However, pulsars are relatively rare, and planets orbiting these pulsars are even rarer, limiting the usefulness of this technique.

11) Direct Imaging:

- Limitations

a)     The parent star is usually much brighter than the planet, so they will most likely block the light.

b)    Planets found through direct imaging are usually around brown dwarfs, which are relatively dim and not much light is detected. 

12) Gravitational microlensing :

- Detection

a)     This technique is premised on general relativity, where the light from a star can be bent by the gravity of an object between the earth and the source star.

b)    The object acts as a lens, where the gravity from the planet will cause further bending or distortion of the light, and such variations in them can be detected. 

- Limitations

a)     However, this technique relies on a chance alignment between the source star, the lens star, and the observer, which is not that common.

13) Astrometry:

- It accurately measures a star's position in the sky and detects how that position changes over time.

- Since a star with a planet will orbit around the common barycentre of the system, the star's position in the sky can be used to detect signs of this orbit.

T3W1 21st Century Advancements in Astronomy:

1)    Gravitational Waves

- The stretching and squeezing of space-time. General relativity states that anything with mass produces gravity which curves space-time.

- To detect gravitational waves: Ligo, the large-scale observatory.

- Gravitational waves are produced by cataclysmic events.

- Can’t be felt as they are too far away that when they reach Earth, the amount of space-time warbling is 1000 times smaller than an atom.

2)    Enceladus

- Sixth largest moon of Saturn (500 Km in diameter)

- Mostly covered by fresh and clean ice

- Many water-rich plumes can be found there

- Cryovolcanoes shoot geyser-like jets of water vapour and other stuff

3)    Cryovolcanoes

- Volcanoes (but ice) that erupts volatiles like water and gases below the freezing point

Water jets:

- Water jets form from hotspots around the geysers which are formed by tidal friction

- Warm liquid water travelling up the cracks and depositing some heat in the surface ice

- The rest of the water is sprayed into space

4)    Sounds of Mars

- Speed of sound: 540 mph compared to earth, 760 mph (Not very noticeable up close)

- Mars’s atmosphere is 100 times less dense than earth which affects how sound waves travel to earth

- Since Mars is made up of 96% Carbon Dioxide, it would absorb more higher pitch sounds

- Lower pitch would travel longer distance

5)    Finding another earth

- Using the Kepler Space telescope, dozens of habitable planets, named exoplanets, have been discovered by astronomers

- These planets have characteristics similar to those found on earth

- An example of an exoplanet would be Kepler-452b, which is the closest to any planet found in the solar system. (500 light-years away)

Characteristics of Kelper-452b:

- Right temperature within the habitable zone

- One and half times the diameter of earth

- Circling a “sun”/star

- Good chance of rocky terrain

6)    Magnetars

- The most powerful magnetic fields

- They are a thousand trillion times stronger than Earth

- Like other stars, they emit bursts of radiation

- Unlike Pulsars, their bursts are not reliable/consistent. They are pretty erratic

7)    The first image of a black hole captured

- The first image of a black hole that we have captured was taken in March-April 2019.

- Discovered using an international network of radio telescopes called the Event Horizon Telescope (EHT) EHT is an international collaboration whose support in the U.S. includes the National Science Foundation.

Why was this discovery so huge?

- A black hole is an extremely dense object from which no light can escape.

- Anything that comes within a black hole’s “event horizon,” its point of no return, will be consumed, never to re-emerge, because of the black hole’s unimaginably strong gravity.

- By its very nature, a black hole cannot be seen. That makes it especially impressive how we have managed to capture this image

- Black holes has also been a large mystery to man so this has helped humans learn more about space, and also intriguing people to find out more

8)    Mapping of Milky way by Gaia

- Gaia is  a mission by the European Space Agency (ESA) made to survey over a billion stars in our galaxy and the local neighbourhood to create a 3D map of the milky way

- Gaia is expected to be able to capture a precise 3D map of over a billion stars

- This will give us data on the Milky Way, such as the structure, luminosity, temperature etc.

- That provides the answers to many of our questions on how the Universe works, our origins, and possibly alien life.

9)    Future of Astronomy/Universe

- 10 to 25 solar masses

- Formed when a star runs out of fuel and collapses

- Core collapses so the atoms are crushed into neutrons

- They are some of the smallest and densest objects in the Universe, other than hypothetical objects and black holes

- They will no longer radiate heat and will cool down after forming

- They have around a surface temperature of almost 600 thousand degrees Celsius when it first forms

T3W2 Food and Nutrition:

1)    What do they eat in space

- Beverages: Water, fruit juice tea etc

-Condiments: Salt, pepper, ketchup etc (Salt and pepper and liquidated)

-Cooked food: Spaghetti, beef etc

-Natural food, brownies, vegetables etc

2)    Calories

-2.2 k for female

-3 k for male

3)    Where is the food from

-They bring more than enough for the mission and are loaded on the shuttle which is stored in lockers on the shuttle.

4)    Criteria

-Lightweight, compact, nutritious

-Crumps like bread, crackers, and cookies don’t do well in space-they float around and get into everything

-Fish will smell bad after a while

5)    Types of food

-Carbohydrates:

i)      The main source of energy-glucose, starch glycogen etc

ii)     Overconsumption leads to weight gain

iii)   Sources: rice, nuts, fruits, sweets, ice cream, starchy vegetables

-Proteins

i)      The sequence of amino acids can range from 2 to thousands

ii)     Functions are- Enzymes, immunity, mechanical support, support, transport

iii)   Sources: all meat products, peanuts, soymilk

-Lipids

i)      Functions are- insulation, storage of energy, important building blocks for biomolecule, protection against mechanical injury

ii)     Sources: Oils, dairy products, foods rich in oil, fat-soluble vitamins

-Vitamins

i)      Vitamin A- Important for vision and immune system

ii)     Vitamin D- Calcium absorption, immune function and protecting bone muscle and heart health

iii)   Vitamin E- serves as an antioxidant, helps maintain body health. They all can be commonly found in vegetable oils, nuts, green leafy vegetables and seeds.

iv)   Vitamin B3-Involve in metabolism, impotant role in oxidation of glucose    

v)     Vitamin B2- precursor to metabolism cofactors, an important role in oxidation in glucose

vi)   Vitamin C-Repair of tissues

-Minerals

i)      Involved in the formation of energy storage molecules, bone, muscles, transmission of nerves impulses, oxygen transport, blood clotting

-Water

i)      Involved in regulation of body temperature, solvent for chemical reactions etc.

T3W7-Relativity

1) Difference between Normal and Special Relativity

a) Special Relativity:

 - Does not work in gravity

  -Does not allow any forces

  -Shows relation between observer, speed & time

  -Published in 1905

  -Simple, and covers less of the universe

b) Normal Relativity

 -Works in gravity

 -Allows and accounts for acceleration

 -Shows relation between observer & acceleration

 -Published in 1915

 -Complex, and covers most of the universe

2)    About Special Relativity

- Laws of physics remain the same in all inertial frames of reference. The speed of light in a vacuum is the same for everything, no matter what or how the motion of the source/ object is. Special relativity explains and shows observers who show movement in constant velocity. 

- It states that space and time are the same. In all inertial frames, the law of physics will be the same. It applies the phenomena in the absence of gravity.  In simple words, the mass of the object becomes infinite when the object approaches the speed of light. Einstein replaces Newton’s constants of space and time with the constant c, the speed of light.

- Then it will not be able to go any faster than the light’s speed. It states that the mass changes as the object move; it is a function of its velocity, and the length of the object contracts (length contradiction) in the direction of motion.

3) About General Relativity

- It is a theory proposed and published by Albert Einstein related to gravity. It states that space-time around the earth is curved due to the planet’s gravity. He published this theory in 1915. 

- It explains that space and time are the same but with different characteristics, thus spacetime.

- The gravitation of force in and around the area of the object/observer depends on how curved the space-time in and around the object/observer is. The energy-momentum of the object’s matter causes the curve. The relation between matter and space-time is such that it tells each other how to behave.

4) Exceptions to General Relativity

a) Singularities

- At the centre of black holes, GR cannot work here, so we need quantum equations. Sadly, the standard model of quantum physics are so far incompatible with GR & SR, as spacetime needs to be measured with absolute precision, and nothing in the standard model can be measured with absolute precision, thus they are incompatible.

5)    What are Geodesics

- In general relativity, a geodesic generalizes the notion of a "straight line" to curved spacetime. Importantly, the world line of a particle free from all external, non-gravitational forces is a particular type of geodesic. 

In other words, a freely moving or falling particle always moves along a geodesic.

6)    What are Geodesics used for in general relativity

- There are three types of geodesics, which are spacelike, timelike and null. There are certaincc velocities one must go to travel on certain geodesics. To travel on spacelike geodesics, v>c , to travel on timelike geodesics, v<c, and to travel on null geodesics, v=c.

7)    Time dilation

- If light’s speed is constant, then even though length AB > CD, light travelling on line CD will have the same speed as the light travelling on AB. Recall the distance speed and time. That means that light travelling on CD has more dist. but uses less time, thus time dilation.

Earth

-Only known planet to sustain life

-Has a diameter of 12 747 km

-Atmosphere has 78% nitrogen, 21% oxygen and 1% argon

-149 million km from the sun

-Has a moon

Moon

-Orbits the earth

-Causes tides

-Has a diameter of 3476 km

-Has moon phases which is basically how much of the moon we see, and its reliant on the relative position of the earth sun and moon

Mercury

-Smallest planet

-Does not have a moon

-58 million km from the sun

-Takes 88 days to orbit the sun and 59 days to rotate 

Venus

-Spins clockwise unlike other planets

-Has a radius of 6000 km

-108 million km from sun

-Has a orbital period of 225 days and takes 243 days to rotate once

-No moons

Mars

-Has 2 moons called phobos and Deimos

-228 million dm from the sun

-Has a radius of 3390 km

-Orbital period of 687 days and takes 1 day to rotate once

Jupiter

-Gas giant (mostly made of helium and hydrogen)

-Has 4 rings

-Its the biggest planet in solar system

-Takes 4300 days to orbit the sun and takes 10 hrs to rotate

-Approximated to have between 80 and 95 moons

-About 741 million km from the sun

-Has a storm called the great red spo, which is estimated to have lasted for about 358 years, and is about 16350 km wide

Saturn

-Also a gas giant

-Takes 29 years to orbit the sun, and takes about 10 hrs 34 min to rotate

-1.434 billion dm from the sun

-83 moons

Uranus

-Ice giant

-Coldest planet in the solar system

-Takes 84 years to orbit the sun and 17 hrs 14 min to rotate

-2.87 billion kilometres from the sun

-27 Moons

-2 Rings

Neptune

-Ice giant

-About 4.5 billions years from the sun

-Takes 165 years to robit the sun and 16 hrs to rotate

-Has 14 moons

-5 Rings

Sun

-27 Days to rotate

-Converts hydrogen into helium through nuclear fusion

Pluto

-Used to be considered a planet but now a dwarf planet

-248 Years to orbit the sun and 153 hrs to rotate

-5.9 billion from from sun

Asteroid belt

-Lies between jupiter and mars

-Is a belt of asteroids