Earth Science - Origin of the Universe

Earth Science - Origin of the Universe

• Big Bang Theory: Proposed by George Lemaître, formulated in 1927; the universe began as a single primordial atom, expanding over 13.7-13.8 billion years.
• Big Bang Theory Characteristics: Started with a singularity; a small, hot, dense state of extremely high density.
• Steady State Theory: Proposed by Sir James Jeans and revised by Fred Hoyle, Herman Bondi, and Thomas Gold. Postulated that despite expansion, the universe's density and mass remain constant, appearing the same throughout; now rejected by most scientists.
• Cosmic Inflation Theory: Supports the Big Bang Theory; describes a period of rapid expansion in the early universe; a rapidly expanding bubble of pure energy.

Earth's Systems

• Atmosphere: A thin layer of gases surrounding Earth; insulates from extreme temperatures, blocks UV rays (made up of 78% nitrogen, 21% oxygen, 0.9% argon).
• Biosphere: The part of Earth that harbors life, varying in conditions from deep roots to high mountains.
• Lithosphere: Earth's solid outer layer, composed of the brittle upper portion of the crust.
• Hydrosphere: All of Earth's water in liquid form, covering about 70% of the surface.

Minerals & Physical Properties

• Mineral Definition: Naturally occurring solid substance with a definite chemical composition; rocks are made of minerals.
• Physical Properties: Include color, streak, hardness, cleavage/fracture, crystal structure, transparency, magnetism, and tenacity.
• Color: Defined by the way minerals absorb light; not a reliable way to identify them.
• Streak: Color of a mineral in powder form; a more reliable indicator.
• Hardness: Measured by resistance to scratching on Mohs Scale (1-softest, 10-hardest).
• Cleavage/Fracture: How a mineral breaks into pieces; cleavage is smooth breaking along crystal structure; fracture is uneven breaking.
• Crystalline Structure: Arrangement of atoms in the mineral crystal; using a hand lens to look for patterns.

Formation of the Solar System

• Nebular Hypothesis: The most widely accepted theory explaining the formation of the solar system; from a rotating gas cloud (nebula) of hot gas; gas cools, nebula shrinks, and rotates faster forming a central hot region = the Sun.
• Planetesimal Theory: A cloud of gas and dust (billions of km in diameter) rotates slowly; cloud shrinks and collapses due to explosion of a nearby star.

Earth Characteristics for Life

• Earth's Position: The third planet from the sun, the only known planet supporting life.
• Supporting Life Features: Water, energy, time, and recycling are Earth's characteristics to support life.

Classification of Rocks

• Igneous Rocks: Formed from the solidification of molten rock.
• Sedimentary Rocks: From the accumulation, compaction, and cementation of sediments.
• Metamorphic Rocks: Formed by the transformation of pre-existing rocks under high pressure and/or temperature.

Geothermal and Hydroelectric

• Geothermal Energy: Power harnessed from Earth's internal heat; three types exist: Dry steam (least common), Flash steam, and binary cycle (uses heat from underground water).
• Hydroelectric Energy: Power from falling water; turbines are spun when water flows which converts kinetic to mechanical energy and electricity.

Soil Conservation

• Soil Conservation: Preventing loss of top layer soil; methods include terrace farming, no-till farming, contour farming, reducing impervious surfaces, planting rain gardens, and restoring wetlands.
• Soil Erosion: Displacement of the upper layer, high acidity, salinity, toxic materials, or overuse.

Waste Management

• Solid Waste: Solids/semi-solids; from houses, industries, etc.
• Hazardous Waste: Industrial, medical, or other potentially unsafe wastes.
• Biomedical Waste: Wastes from hospitals and medical institutions.
• Biodegradable Waste: Organic materials decomposing into carbon dioxide, water, methane, etc.