UNIT 1: Origin And Understanding Of Universe Flashcards
(128 cards)
One of the earliest and famous hypothesis was given by German philosopher
Immanuel Kant
In 1796 what theory was given by a Mathematician_____________ and what did the theory state
Nebular Hypothesis
Laplace
Sun was rotating, slowly and the formation of planets was associated with a cloud of material related to a youthful sun.
A wandering star approached the sun. A material was extended in cigar shape and got separated from the solar surface. With the moving of the passing star, that separated material from the solar surface continued to revolve around the sun and then got condensed slowly forming the planets;
Who, When, who all supported it, what were the arguments called and why
Chamberlain, Moulton
1900
Sir James Jeans, Sir Harold Jeffery
“Binary theories”-the arguments considered a companion to the sun to have been coexisting, an these arguments are called binary theories
Later, who are revised the nebular hypothesis when and what was it
Otto Schmidt in Russia and Carl Weizacar in Germany, 1950
They argued that the sun was surrounded by a solar nebula containing mostly hydrogen, helium and dust. It also argued that a disk-shaped cloud was formed due tot he friction and collision of particles, and the planets were formed through the process of accretion. However, later scientists took up the problems of the origin of the entire universe and not just that of the earth or the planets.
Who and when provided the evidence suggesting that the universe is expanding or we can say that the distance between the galaxies were found to be increasing, as the time crosses, galaxies will further move apart.
1920 Edwin Hubble
What are the three stages of Big Bang theory
- “Tiny ball “ (singular atom) at one place, which had infinite temperature and density, and an unimaginably small volume
- It exploded. First atom began to form within the first three minutes
- The temperature dropped to 4500K within 300,000 years and the atomic matter emerged
When did Big Bang take place
13.7 Billion years ago
What is an alternative Bigbang theory
Hoyle’s concept of steady state
Why was Hoyle’s concept of steady state regected
Cause it proposed that the universe would be of the same size at any given point of time
Evidence that proves that the Universe is expanding
- Redshift of the objects in the universe
- Hubble law
- The presence of Cosmic Microwave background
Redshift of the objects in the universe
Movement of objects relative to us is measured using the Doppler shift. Done by measuring the frequency of the objects. Light also has a Doppler shift.
Light coming towards us: blue shift
Light going away from us: red shift
Hubble law
This law suggests that the velocity of recession is proportional to the distance of the galaxy from us. Astronomer, Edwin Hubble measured in 1929, the velocities of a large selections of galaxies and found that the majority of galaxies are moving away from us.
Cosmic Microwave background
According to the Bigbang, theory, the early universe was a very hot place and the gas within it get cool, as it expands. This means there should be radiation, meaning the leftover heat from the Big Bang, called the “cosmic microwave background”, or CMB all over the universe. Thus, the existence of the CMB radiation was observed in 1965 by Arno Penzias and Robert Wilson. Presently, the the temperature of the CMB radiation is at 2.725degrees above absolute zero
The existence of CMB was observed in ____ by______. Presently the CMB radiation is at _______
1965
Arno Penzias, Robert Wilson
2.725˚ above absolute zero
_____________ gave rise to gravitational forces
Density differences
Hydrogen gas started accumulating as a huge cloud called
Nebula
Nebula——> ______————> __________———->
Localised clumps of gas
Dense gaseous bodies
Stars
When was stars formed
5-6 billion years ago
Individual galaxies have diameters ranging from
80,000-150,000 light years
What are the types of Galaxies
3 types
- Elliptical galaxies: spheroid or an elongated sphere shape; two dimensional
- Spiral galaxies: Bulge, disk or halo; Milky Way
- Irregular galaxy: No regular shape; asymmetrical
The condensation of gas cloud develops as small circular objects around the core. With the help of the process of cohesion, these small circular objects develop into ________ which comprises a large number of small bodies
Planetesimals
When was the solar system formed
9 billion years ago; 4.5 billion years ago; conflicting sources
Stages in which solar system was formed
- Supernova
- Solar Nebula
- Formation of the sun
- Formation of other planets
Solar system comprises of
- Planets
- Dwarf planets
- Moons
- Asteroids
- Comets
- Meteoroids
