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Transcript of Big Bang
by Dr Roy
Actually, it's by Richard Wang...
What is the Big Bang?
Actually, this is by Richard Wang...
According to many scientists, the Big Bang Theory is how the universe
As of 2013, the universe is around 14 billion years old.
Ever since 1929, the universe has been shown to be growing.
Edwin Hubble, the man who discovered the universe was growing.
Edwin Hubble used this as evidence
This theory states that the universe started from one
small area in space
Not this type of violence...
Which then started to grow, due to a single, violent
...nor this type...
... and definitely not this type.
It was more something along these lines...
Give or take 0.037 billion years
to prove something already thought to happen
A theory proposed by Georges Lemaître
On a much larger scale
More specifically, everything
was crammed into one single place
(that means everything that exists)
was stuck in one spot
Nobody knows how long things stayed that way
But then, for some unknown reason, everything
In the middle of a field
you have a hand grenade
Let the grenade=x... or better still, let it represent all the matter that makes up the universe, in a hot and dense state
Let the field represent all the space there is
A guy/gal comes along
The shrapnel that explodes out, is mainly hydrogen, but as it cools, there are traces of helium and lithium
The initial "Big Bang" is thought to have taken 0.000000000000000000000000000000001 seconds
For those not bothered to count zeroes, that would be 10 to the power of -43 seconds
(a strange form of energy is used to unlock all the matter)
During the next 0.000001 seconds (next millionth of a second), the universe continues to expand, except not as fast as in the first phase.
The first gravity appears, followed by the rest of the forces (that can be found in nature today); the forces keeping nuclei together
Whilst it expands, matter spreads out,
making it less dense, and cooler.
and then the electromagnetic forces appear
After 3 seconds, the basic elements were formed;
Actually, none of those were the three basic elements
some of which then became
After 300 million years, the universe continued to
expand, gravity amplifies irregularities in the gaseous primordial conglomerate
These small irregularities become more dense, until the gas ignites... et voila, and stars are born
Groups of stars group together, and become
the first galaxies
Through this process a star is born 5
billion years from now
However, even as this prezi is being viewed,
There are three main types
(based on their shape)
Through the Hubble Classification Scheme,
For example, look below:
Elliptical galaxies range from E0 to E7; E0 is just
about spherical, whilst E7 is extremely elongated and flat
They are characterised, not just by their shape
but also by their lack of star-making gas
which affects the shape of the galaxy.
Also the motion in these galaxies is radial
That means that the stars within these galaxies travel in a circular motion, not rotating about an axis
And most stars within are old and there aren't many open clusters (groups of a couple of thousand stars of about the same age) within the elliptic galaxies
They consist of four important parts:
A flat disc of mainly new stars and interstellar matter traveling in rotational motion (about an axis)
A halo of stars (which tend to be obscured by dark matter)
A central bulge (a dense cluster of stars which contain mainly old stars)
And at at the centre of the whole galaxy, there is a supermassive black hole, through which the (imaginary) axis passes through
They may be barred spiral
or just spiral
The barred spiral galaxies appear to have a bar across, almost like a diameter, whilst the spiral galaxy has no bar.
This means that there are two different Hubble classifications for spiral galaxies
As you can see, they fork out from s0( lenticular galaxies), which has characteristics of elliptical (old stars) and spiral galaxies (ill-defined arms)
To barred spiral
Both are judged by the distance of their arms.
These galaxies have no clearly defined shape
There are two types
Irr-I (Feature some characteristics of other types, but enough for classification)
Irr-II (Do not feature any characteristics of other types)
Types meaning Hubble Classification
The Large Magellanic Cloud is an Irr-I Galay, because it shows some signs of a bar spiral galaxy.
NGC 1427A is an Irr-II galaxy as it has no characteristics that can class it as either elliptical or spiral.
Many Irregular galaxies are deformed because of the gravitational pulls of other galaxies, having once been one of the other two types
They are also abundant in interstellar matter
The formation of galaxies is still a mystery today
But we have some notion as to their origins
One model states that groups of stars collided with bodies of gas and dust.
They began to rotate around a central mass
Causing the mass to contract, and turn into a "flat" disk
Whilst this serves as an explanation for spiral galaxies, computer models have shown that most collisions between spiral galaxies form elliptical or irregular galaxies
The amount of time taken to create a galaxy would be approximately 400million years.
They mainly form in nebulae, such as the Crab Nebula
Nebulae are large clouds of dense interstellar matter (gas, dust and other stuff.
Some regions in the nebula have a gravitational centre
Which attracts other atoms, gas and dust
towards the centre, where they collide, heating up the centre
As they gain mass,
their centres grow hotter.
Density of the core increases
Gas pressure increases
Gas resists collapse of the Nebula
When gas pressure equals gravity, the "star" has a balance of forces (equilibrium)
This equilibrium is important; if lost
the star dies
but to first become a star, it needs to reach a certain temperature.
If it doesn't, it becomes a brown dwarf, not a star
If it does, then there is nuclear fusion, and a star is formed
After becoming a star, depending on the original mass, it may become one of three things, as shown below
As you can see, stars are classified by their size and age
With certain stars, you have planetary systems
Planetary systems are systems of non-stellar
bodies bound to star(s) by gravity
The main source of information on the development and evolution of planetary systems
comes from knowledge on the development and evolution of our own planetary system
known in many texts and games as the Sol System, but by us as the Solar System
While the first 700 million years are not too clear
it is widely believed that the solar system began to form when the sun was formed
from leftover dust and gases
which started to spin around the sun
Minute particles of dust accrete through swirling gas and grow in size
They collide with other similar bodies and grow
they accrete dust and smaller bodies and move towards the sun
Within a million years of the sun's birth, these small bodies- planetismals- are no wider than a kilometre
In a planetary disk around the sun:
yet they have used up most of the dust from the planetary disk
after a few more collisions, and some planetismals began to grow into planetary embryos
Within ten million years, the gas giants began to form
Jupiter first then Saturn, by a few million years
Because Jupiter came first,
It helped develop Saturn, then Uranus and Neptune develop
However, because it came first, there was less gas for Saturn; hence its smaller size
This made Jupiter the oldest and largest planet
to be more specific
it used its gravity to draw in gas and planetary material
Which helped them grow
Things stayed mainly that way, with 4 planets basically formed, and planetismals everywhere
As they developed later, they were smaller