Earth and Life Science

• Theory - is a coherent group of tested general propositions (tried-and-tested hypothesis) that have provided the scientific world with a good start with explaining natural phenomena.
• Hypothesis- is an idea that is not proven yet but that leads to further study or discussion.
• Universe is everything. Universe begins 13.7 Billion years ago.
• The UNIVERSE is the totality of known or supposed objects and phenomena throughout space.
• Hydrogen, helium, and lithium are the three most abundant elements.
• A galaxy is a cluster of billions of stars and clusters of galaxies form superclusters. In between the clusters is practically an empty space. This organization of matter in the universe suggests that it is indeed clumpy at a certain scale. But at a large scale, it appears homogeneous and isotropic.
• Stars - the building block of galaxies-are born out of clouds of gas and dust in galaxies. Instabilities within the clouds eventually results into gravitational collapse, rotation, heating up, and transformation into a protostar-the hot core of a future star as thermonuclear reactions set in.
• Cosmology is the study of the origin, development, structure, history, and future of the entire universe.
• George Lemaitre - Origin of Big Bang Theory
• • The universe began as a tiny, dense, fireball called singularity that exploded and it expanded. • "all the matter and energy in the universe are crammed into a tiny compact point sometimes called "singularity"
• Evolutionary Theory - Density of matter decreases over time
• Steady State Theory - Density of matter is constant over time.
• Oscillating theory- All the matter in the universe would get hotter and brighter and eventually collapse together in an event called "BIG CRUNCH" or "BIG BANG"
• Inflation Theory- Believed to happen just 10-36 seconds after the Big Bang.