2 March 2022 

I learned of the different events and activites that we will do in the cca, I also learned a little on how telescopes work and the two different types of a telescope, a reflector telescope and a refractor telescope.

9 March 2022

The Beginning

The universe expands and as it expands the universe cools at a very fast pace, although the universe is cooling down, the quarks still cannot merge.When the universe is cool enough, the electrons, protons, and neutrons to form.Electrons and Nuclei form atoms.The universe became transparent to photons.The Cosmic Microwave Background Radiation is caused by these things. 

- Grand Unification —

-Only 3 of the four fundamentals forces were unified:

-Strong Nuclear Force — Strong force binds the nucleus of atoms

-Weak Nuclear Force — Radioactive decay

-Electromagnet Force — Electromagnetic force binds atoms

- Inflationary, Quark, Hadron

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

-This resulted in three forces taking up their present forms (same as today). -However, it was still too hot for quarks to form hardons.

-When the temp dropped, quarks began to form hadrons, and Hadron Epoch started.

-The Universe became cool enough for electrons, protons and neutrons to form. Protons and neutrons combine to form nuclei.

However, electrons did not bind to nucleic, and the Universe was just a sea of nuclei, electrons and protons.

Recombination Epoch

-Electrons and Nuclei from atoms

-Universe became transparent to photons

-Cosmic Microwave Background radiation originates from the epoch

After the Dark Ages:

-Universe became transparent, allowing light to travel long distances, but there were few light sources

-The Universe contained only hydrogen gas and background radiation leftover from the big bang.

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

-These stars were classified as Population 3 stars

-They virtually had no metals

-Extremely massive, between a few hundred to 1000 solar masses

-Extremely luminous

-The birth of stars accelerated as the Universe left the dark ages

-Denser lumps of matter around the Universe gave rise to the rapid formation of stars as gravity caused them to clump together.

-The further clumping of protostars were caused by gravity, which formed protogalaxies, which became larger over time.

Galaxy mergers

-Gravity eventually caused galaxies to merge together, forming larger galaxies

-Most of the early large galaxies were spirals, but merging caused them to become more elliptical

Birth of planets

-The Sun and the planets formed together 4.6 billion years ago from a cloud of gas and dust called a solar nebula.

-The Sun formed in the centre, and the planets formed in a think disk orbiting around it.

• Before the sun ignited, planetesimals were formed from small bits of dust and gas clumping together amidst the accretion disk.

-Planetesimals then collided with each other to form larger planets due to gravity

Cooling down

-A lot of collisions occurred during this process, as debris rained down on larger objects, generating a lot of heat

-As the amount of stray debris reduced, either by colliding with objects or getting flung out of orbit by unstable gravitational fields, the rate of collision decreased, decreasing the amount of heat generated.

The Moon

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

-The resulting debris from both Earth and the impactor accumulated to four natural satellites

-At first, it was molten, then it crystallised within a 100 million years

Types of Black Holes

-Stellar Black Holes - Formed from the collapse of stars

-Supermassive Blackholes - Black holes with millions of solar masses,

-Primordial Black Holes

A singular point at the centre of a black hole is called the Singularity is so dense that space-time starts to curve.

--Stellar Black Holes

-Formed if a neutron star absorb enough material from a nearby binary star or other objects

Black Holes can be formed as long as cores of collapsed stars are greater than five solar masses, causing an escape velocity greater than the speed of light

-Stars must be greater than 20 solar masses for the above-stated condition to occur 

Formation of early supermassive black holes

-Clouds of gas in the early Universe have variation in density, and those that are super dense created black holes immediately

--Large stars formed during the early stage of the Universe created supermassive black holes

Types of stars

• Low mass stars

• Intermediate mass star 

• High Mass Stars

Nuclear Fusion

Nuclear fusion is when two different molecules collide with each other with intense forces to the point where they fuse.

This releases massive amounts of energy.

Low Mass Stars

Stars with more than 25% solar masses will expand into a red giant during helium fusion. It will shed most of its mass as a nebula and turn into a white dwarf.

Stars with less than 25% solar masses are not capable of fusing Helium, so they will just collapse into a white dwarf. It can take trillions of years for them to run out of fuel.

Intermediate Mass Stars

These stars are usually heavier but not heavy enough for huge explosions, such as our sun.

These stars are capable of using Helium in heavier elements, such as carbon and oxygen.

This, in turn, shortens the lifespan of these stars. They will turn into red giants and eventually collapse into white dwarfs.

White Dwarfs

White Dwarfs are the remnants of low-intermediate mass stars. They are extremely dense and have a mass of about the suns while having a volume of about the Earth's.

High Mass Stars

These stars are the most extreme stars in the Universe. They are 10 to 70 times heavier than our sun.

This is enough for them to implode and cause massive explosions and the formation of other celestial bodies.

They can turn into different bodies

Supernovas

Type 2 supernovas

The cores of stars are usually obliterated or turns into other things during this process. So white dwarfs are very uncommon to appear.

High-mass stars have a lot of nuclear energy in them to counter their own gravity.

But as it runs out of fuel, there isn't enough nuclear energy to counter its own weight. When a star does not have enough nuclear energy to resist gravity, it collapses within itself causing a type II supernova. 

Type 1 supernovas

For this type of supernova, it involves one white dwarf orbiting another star.

The other star could be another star

This then leads to the White Dwarf exploding

The same explosion can also be produced from 2 white dwards colliding

Usually, the white dwarf accumulates matter from the other star.

Neutron stars

This is one of the things a huge star becomes after exploding. 

Pulsars

This is the most common form of Neutron Stars

They emit pulses of strong energy at intervals

They also have very strong magnetic fields which shoot out particles from each poles

The particles are seen as beams of light

Magnetars

Another type of neutron star is called a magnetar.

In a typical neutron star, the magnetic field is trillions of times that of the Earth's magnetic field

However in a magnetic field is another 1000 times stronger

In a magnetar, with its huge magnetic field, movements in the crust cause the neutron star to release a vast amount of energy in the form of electromagnetic radiationT

Black Holes 2

When the star collapses, an imaginary srufce called the event horizon forms, this is the point where light cannot even escape from the gravity of the Black Hole

According to the theory of relativity, under the influence of strong gravitational forces, time starts to slow donw

At the event horizon, the surface of the Star will stop moving and can no longer collapse further

Anything beyond the event horizon is unknown

The End

The death of solar systems

-As Stars explode, planets that reside near it's stars will get vaporised as the star goes through the red giant phase and expands rapidly

-If a supernova occurs all the planets in the solar system will get vaporised

Proton Decay

A hypothetical form of particle decay in which the proton decays into lighter subatomic particles such as positron and pion'

Proton Decay is hypothetical as it has never been observed to decay.

Degenerate Era

Black holes 'survive' by pulling objects into it's event horizon

When space become so vast that blackholes cant consume matter, nothing really happens to it. However, if you observe it for long enough you would be able to see that it slowly becomes smaller.

At the end of this process, the black hole lights up the universe for the last time.

The Death of the Universe

Some Theories: Big Crunch, Big Freeze, Big Rip

 The expansion of the universe reverses and the universe re-collapses. This causes the cosmic scale

This happened when all the heat and energy is evenly spread over big distances.

The universe, atoms and subatomic particles and even spacetime itself, is progressively torn apart by the expansion of the universe at a certain time till distances between particles become finite.

Reflection of the day: The topic that most interested me was Pulsars. I like the videos and animations included in the presentation that helped me understand and visualise better on the topic being explained.

23 March 2022 

Extra-Terrestrial Life

Table of contents:

-Habitability

-Fermi Paradox

-Dark Forest Theory

-Communication

-Seager Equation

Habitability: The basis of all life

Basic needs of life: Water, sufficient amounts of certain air qualities, food

-Some important elements include Carbon, Hydrogen, Oxygen and Nitrogen

Habitable Zone

-AKA, the Goldilocks Zone, it is a region where planets can be at a sufficient temperature that is not too warm or too cold

-This allows us to gauge possible planets that contain life

Fermi Paradox

Definition: Apparent contradiction for the lack of evidence and high probability estimates for the existence of extraterrestrial civilisations

The Great Filter: The absence of any sign of intelligent life in space would mean that one of the steps is improbable to work, if one step fails, the said intelligent life would start from scratch

An "evolutionary path" in which intelligent life would have to take before discovering us or other colonies of extra-terrestrial origin;

-The right star system (including organics and potentially habitable planets)

-Reproductive molecules (e.g RNA)

-Simple (prokaryotic) singe-cell life

-Complex (eukaryotic) single-cell life 

-Ability to reproduce

-Multi-cell life

-Tool using animals with intelligence

-A civilization advancing toward the potential for a colonisation explosion (where we are now)

-Colonisation explosion 

How to find the amount of habitable planets?

The Drake Equation

N = the number of civilizations in our galaxy with which communication might be possible (i.e. which are on our current past light cone);

R∗ = the average rate of star formation in our Galaxy

fp = the fraction of those stars that have planets

ne = the average number of planets that can potentially support life per star that has planets

fl = the fraction of planets that could support life that actually develop life at some point

fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)

fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space

L = the length of time for which such civilizations release detectable signals into space

The Dark Forest Theory

It's to be the hunter or to be hunted 

Communication

-To find possible extra-terrestrial life, radio signals are used

-SETI are scientific searches using electromagnetic radiation for signs of transmission

-Recently, they have proposed using Quantam communications as a way to try and communicate with Aliens

Technosignatures:

-If alien life were to be advanced enough, we would find megastructures, acting as a sort of lighthouse

Seager Equation

-This equation is a reworking on the Drake Equation

Reflection for today: 

I learnt that trying to find other intelligent extraterrestrial life is very difficult as there are too many factors to consider, some which are rare to find, I also learnt about the ways of communication with other life, two examples are radio waves or electromagnetic radiation. I can use this knowledge to teach others who are curious about the same topic. I think that the lesson could have more information on the Dark Forest Theory part and I think that in the future, I would like to see more similar theories as I think they are very interesting. 

30/03/2022

Black Holes

Table of contents:

1: Black Holes

2: Parts of Black Holes

3: Theories of Black Holes

1;

-What is a Black Hole?

A black hole is a place in space where gravity is so strong that even light cannot escape it.

-How do we see one?

We can't since its strong gravity pulls all the surrounding light to the center of the black hole. However, we can observe the presence of a black hole by its effect on its surroundings. Scientists can observe how the strong gravity affects the stars and gas around the black hole.

-How big and heavy are there?

It can vary greatly. The smallest black holes can be as small as one atom, yet they have a mass of a large mountain. The largest black holes can be as big as a few million Earths combined, and they have a mass equal to around 4 million Suns.

-What types of black holes are there?

There are 4 types: stellar-mass, intermediate, supermassive, and miniature

Stellar-mass: They are the most common black holes, ranging from five to tens of times the mass of the Sun.

Intermediate: Significantly more massive than a stellar black hole. However, it has less mass than a supermassive one. Intermediate black holes range from 100 to a million times more massive than our sun.

Supermassive: Largest type of black hole; ranging from millions to billions of times the mass of our sun.

Miniature: Hypothetical tiny black holes. The size of these black holes may be equal to or above 22.1 micrograms, which is about one- millionth of a gram. 

How are black holes created?

Stellar-mass: When the center of a very big star falls in upon itself or collapses. When this happens, it causes a supernova. A supernova is an exploding star that blasts part of the star into space.

Intermediate: It is too massive to be formed by the collapse of a single star. One theory as to how intermediate black holes are formed is that stellar black holes gravitationally attract other stellar black holes or compact objects. The merging of these black holes and compact objects form an intermediate black hole. 

Supermassive: The formation of supermassive black holes are still unconfirmed. Some have suggested that supermassive black holes form out of the collapse of massive clouds of gas during the early stages of the formation of the galaxy. 

Miniature: A black hole formed soon after the creation of the universe is called a primordial black hole and is the most widely accepted hypothesis for the possible creation of a micro black hole.

How to photograph black holes?

 Event Horizon Telescope; capture an image of a black hole. The degree of precision makes the EHT capable of resolving objects about 4000 times better than the Hubble Space Telescope.

Very Long Baseline Interferometry: creating an array of smaller telescopes that can be synchronized to focus on the same object at the same time and act as a giant virtual telescope.

2;

Event Horizon: infamously known as the "point of no return". Once matter is inside it, that matter will fall to the center. With such strong gravity, the matter squishes to just a point -- a tiny, tiny volume with a crazy-big density.

Singularity: That is the point, it is vanishingly small, so it has essentially an infinite density; which makes it likely that the laws of physics break down at the singularity.

Spaghettification

The singularity is found at the center of a black hole, and it exerts a strong gravitational force for any objects that falls in. This process is known as Spaghettification

3;

White Holes: The polar opposites of a black hole. Also contain a singularity, but they operate in reverse whereby nothing can enter the event horizon of a white hole, and any material inside the white hole gets ejected immediately.

Wormholes: White and Black holes are connected because the two holes would exist in separate places in space, a tunnel -a wormhole- would bridge the two ends. It describes Einstein's theory of general relativity that connects two distant points in space or time via a tunnel.

However, wormholes would not be very useful:

1) Super unstable. If a particle dropped towards the event horizon of a white hole, it would never reach since nothing can enter a white hole. = energy of system increases to infinity and white hole explodes 

2) The only way to enter this kind of wormhole would be to cross the event horizon of the black hole on the other side. But once an object crossed the event horizon, it could never escape. So objects can enter it but cannot leave it.

How would they look like?

The entrance would be a sphere, like the surface of a planet. If you looked into it, you would see light coming in from the other side. The wormhole tunnel could be any length, and while travelling down the tunnel, you would see distorted views of the region of the universe you came from and the region you were travelling to.

Time travel using Wormholes;

A wormhole could also act as a time machine. Special relativity dictates that moving clocks run slower. In other words, someone racing around at nearly the speed of light would not advance into their own future as quickly as someone standing still.

If scientists could somehow construct a wormhole, initially the two ends would be synchronized in time. But if one end were then accelerated to nearly the speed of light, that end would start to lag behind the other end. The two entrances could then be brought together, but then one of the entrances would be in the past of the other.

Hawking radiation

Quantam fluctuations - the temporary random change inh the amount of energy in a point in space

Annihilation 

Eons - a unit of time equal to a thousand million years 

It is the thermal radiation predicted to be spontaneously emitted by black holes. It arises from the steady conversion of quantum vacuum fluctuations into pairs of particles, one of which escaping at infinity while the other is trapped inside the black hole horizon.

Reflections:

I learnt that black holes are about many space objects, theories such as White holes, wormholes, some theories I learnt are Hawking Radiation and how a wormhole looks like. I also learned some new terms such as Eons and Quantum fluctuations. I can apply this in real life by possibly teaching other people who are also interested in the topics that I learnt and learning more about some topics that I have still questions about online. I think that in the future I would like to see similar topics like how white holes are formed.

6/4/22

Exoplanets

In the Beginning

What are exoplanets?

Exoplanets are planets that are outside our solar system.

They orbit their own stars, forming their own solar systems.

Free-floating exoplanets

called Rogue planets, they don't belong to a solar system, some might have been kicked out of their previous system.

There are 4 methods of detecting them. One example of an Earth-like planet is the Kepler-186f. 51 Pegasi b - Half the mass of Jupiter and orbits its star once every four days. Kepler 444 system, the oldest known planetary system has five terrestrial-sized planets.

Other notable exoplanets:

Kepler 22b - a possible planet that contains water

Kepler 69c 

Kepler 452b - the first earth-sized planet found in the habitable zone

Kepler 62f

4984 exoplanets have been found as of 1 April 2022

How to detect exoplanets

-Doppler spectroscopy

-Centre of gravity

Barycenter is the centre of gravity for objects

The Barycenter will wobble due to the planet's gravity also acting on the star

The star mass > The planet mass ---- Centre of mass will usually lie within the star 

-Transit-timing variation

Transit-timing variation is a method for detecting exoplanets by observing variations in the timing of a transit. This provides an extremely sensitive method capable of detecting additional planets in the system with masses potentially as small as that of Earth.

Pulsars

What are they? Pulsars are rotating neutron stars observed to have pulses of radiation at very regular intervals that range from milliseconds to seconds.

Pulsars have strong magnetic fields which funnel jets of particles out al

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

 Limitations;

The parent star is usually much brighter than the planet, so the light will block out the planets. Planets which are found through direct imaging are usually round brown dwarfs which are very dim.

Detection

Premised in General Relativity where light from a star is bent due to the gravity of an object between the earth and the source star.

Astrometery

Astrometry involves measuring a stars position in the sky accurately, and detecting how that position changes over time.

Reflection for the day:

I learnt about the various methods of detecting exoplanets, learnt what are Pulsars and what are Rogue planets. I think that the lesson was pretty fun and I feel that no improvements are needed. I want to learn about how to look do stargazing next time. I can apply this in real life by sharing this information with other people to get them interested in astronomy.

20/4/2022

Rovers and Space Exploration

What are rovers?

They are exploration devices designed to traverse extraterrestrial surfaces.

Rovers can have multiple uses:

• Transporting human spaceflight crew

• Partial/fully autonomous robot

• 
  

Rovers collect data about terrain and collect crust samples such as dust, soil, rocks, and even liquids. They are essential tools in space exploration.

Rovers can have many objectives, but their main ones are:

- Determine the geological processes that shaped the terrain of the region

-Study the composition of rock and soil to find evidence of water

- Study the environmental conditions that existed when liquid water was present and access whether life could develop there.

Important discoveries:

Presence of water on Mars

Location what possibly supports life

Reflection of the day:

I learnt about the parts of rovers and their purpose , I also learnt some important discoveries that were made from rovers on mars such as opportunity and perseverance. For the next lesson, I want to learn about the special parts of the rovers and how they work in detail.