Earth and Life Science

• The Science of Cosmology provides various hypotheses that explain the origins based on its present properties or characteristics.
• ·        It should be likewise be noted that advances in scientific tools and instruments continuously help validate theories.
• Big Bang Theory

  Remains to be the prevailing cosmological model for the early development of the universe.
• Cosmic Microwave Background (CMB) is a thermal radiation used in the observational cosmology because it is considered the oldest light in the universe.
• q  According to the Big Bang Theory, the universe was once very small and very hot, and then it expanded over time until it reached its peak 13.7 billion years ago.
• 1.      Steady State Theory

  q  But it was revised by Fred Hoyle, Hermann Bondi and Thomas Gold and it gained popularity

  q  This theory states that the universe is always expanding in a constant average density

  q  This theory further claims that the universe has no beginning or end time and even though it is expanding, its appearance remains the same over time.
• q  Inflation refers to the rapid expansion of space time.
• Cosmic Inflation Theory According to this theory, the early universe was a rapidly expanding bubble of pure vacuum energy and it did not have any matter or radiation.
• Nebular Hypothesis It presupposes that around 4.6 billion years ago, a star system was formed from a rotating gas cloud or nebula of extremely hot gas.
• Planetesimal Theory According to this theory, when a planetary system is forming there is a protoplanetary disk with materials from nebula from which the system came. This material is gradually pulled together by gravity to form small chunks.
• Tidal Theory It is also known as “Encounter Theory”.
• Oblate Spheroid - the shape of the Earth.
• Earth got its present shape specifically because its gravity and rotation
• the geosphere may be taken as the collective name for the lithosphere.
• below the crust is the mantle
• the crust consist of a 5-70 km thick layer of oceanic and continental crusts.
• the asthenosphere that explains the occurrence of earthquake and seismic activities.
• Mantle - It is considered as the thickest layer of the earth.
• the core is chiefly made up of iron and nickel.
• the outer core is known to be liquid while the inner core is solid.
• The Gutenburg discontinuity. This boundary does not remain constant because of changes in heat flow. It serves as a transitional boundary between the lower mantle and the outer core.
• Lehman Discontinuity. With this distinct behaviour of the waves, it was accepted that there indeed lies a layer that separates the inner core from the liquid outer core.
• Mohorovicic Discontinuity – the boundary between the Crust and the mantle.
• Repetti Discontinuity – (William Repetti) The boundary between upper mantle and lower mantle.
• ATMOSPHERE

  -mass of air surrounding the Earth
• 1.      HYDROSPHERE

  -        All the waters on earth, including subsurface and atmospheric water.
• ·        SALT WATER (97 %)

  highly salinity

  • found in oceans and seas
• ·        FRESH WATER (3%)

  • safe for human consumption
• -        The biosphere is where certain organism function to consume a different set of organisms to allow energy transfer from one group of organism to another and to allow certain materials to recycle.
• -        Energy is transferred from one organism to another in a food chain.
• -        Population – group of organisms of the same species
• -        Community – group of different populations
• -        Ecosystem – group of different communities interacting with the

  -        environment
• -        Biosphere – combination of all ecosystem
• James Hutton is recognized as the founder of modern geology. In his theory of uniformitarianism he asserted that the same geological forces acting on and shaping earth today are the same those that operated in the past.
• 1. Charles Darwin was an English naturalist known for the theory of evolution. He developed revolutionary theory on the origin of species that was contrary to the popular view of naturalist during that time.
• 1. Andrija mohorovicic was a Croatian meteorologist and seismologist who suggested that there lies a boundary between the crust and the mantle because of the difference in the behavior of the seismic wave. He is known to be one of the founder of modern seismology.
• Beno Gutenburg the one who discovered the gutenburg boundary that lies between solid silicate.
• Inge Lehmann she discovered a seismic discontinuity while on a collaborative study of earth crust and upper mantle with other scientist.
• Alexander Oparin he proposed the primordial soup theory in 1924.