ELSCIE REVIEWER

• Big Bang theory


  Imagining a huge explosion that happened around 13.8 billion years ago, which is thought to be the beginning of our universe
• Galaxies, including ours, are all moving away from each other
• Big Bang theory


  The explanation for how our universe started and why galaxies are spreading out
• Before the Big Bang

  Everything in the observable universe, including all matter and radiation, was squished into a tiny, hot, and dense mass, just a few millimeters across
• The Big Bang


  Around 10 to 20 billion years ago, there was a massive explosion that gave birth to everything in the universe we know today—matter, energy, space, and time itself
• Explosion and Expansion


  1. Right after the Big Bang, the universe expanded rapidly from its tiny starting point to its vast size today

  2. This expansion happened incredibly fast at first and has continued more slowly over billions of years
• Evolution of the Universe

  1. After the Big Bang, as time passed and the universe cooled down, different kinds of atoms began to form

  2. These atoms eventually came together to form stars, galaxies, and everything else we see in the universe today
• The Big Bang theory suggests that the universe started from a tiny, incredibly dense point and has been expanding ever since, giving rise to everything we know today
• A Belgian priest named Georges Lemaitre proposed the Big Bang Theory


  1920s
• Lemaitre suggested that the universe began from a single, incredibly dense point known as a primordial atom
• Lemaitre's idea gained support from Edwin Hubble's observations of galaxies moving away from us in all directions and the discovery of cosmic microwave radiation by Arno Penzias and Robert Wilson
• Cosmic microwave background radiation


  The oldest radiation known, believed to be a leftover glow from the Big Bang, which is used for transmitting TV signals via antennas and holds valuable information about the early universe
• The Big Bang Theory still leaves some big questions unanswered, including what caused the Big Bang in the first place
• Big Bang and Inflation

  1. The universe began with the Big Bang about 13.8 billion years ago

  2. Right after this event, there was a period of rapid expansion called inflation, where the universe grew hugely in a very short time
• Detecting Gravitational Waves


  1. Scientists have been looking for direct evidence of inflation

  2. They found it in the form of gravitational waves, which are like ripples in space caused by massive cosmic events

  3. These waves were detected using special technology on a telescope at the South Pole
• Gravitational waves from inflation leave a distinct pattern in the cosmic microwave background, a faint glow left over from the early universe
• How They Did It

  1. They used advanced detectors cooled to extremely low temperatures, almost absolute zero, and a large array of detectors similar to pixels in a camera

  2. This allowed them to capture the faint signals of gravitational waves
• This discovery confirms our understanding of how the universe expanded and gives hints about the forces at work during this early period
• Heliocentric system


  The idea that the Sun is the center of our Solar System, and the Earth is just one of the planets going around it
• Ptolemaic System


  The idea that the Earth is the center of the Solar System, with everything else revolving around it
• In 1543, Nicolaus Copernicus suggested the heliocentric system, putting the Sun at the center instead of the Earth
• Theories about how the solar system formed

  • Nebular Hypothesis
  • Planetesimal Theory
  • Dust Cloud Theory
  • Protoplanet Hypothesis
• Nebular Hypothesis


  The solar system formed from a huge cloud of gas and dust swirling around the young Sun, which condensed and flattened into a disk, with rings of material breaking off to form planets and their moons
• Planetesimal Theory


  Passing stars caused tidal forces that pulled material away from the Sun, forming clouds of gas and dust that collapsed to form small bodies called planetesimals, which collided and grew into planets
• Dust Cloud Theory


  The solar system formed from a cloud of gas and dust, mainly hydrogen and helium, with a small amount of heavier elements, which flattened into a disk and formed swirls that condensed into planets and moons
• Protoplanet Hypothesis


  The original cloud of gas and dust was so massive that it broke into separate clouds, or protoplanets, which eventually formed planets, and as the Sun grew hotter, it emitted radiation that drove away leftover material, leaving behind planets and comets
• Scientists are still working to understand exactly how our solar system formed
• Main layers of the Earth

  • Crust
  • Mantle
  • Core
• Crust


  The outermost layer of the Earth, ranging from about 5 to 70 kilometers thick, where landforms like mountains and valleys are formed
• Mantle


  The dense, molten (or semi-molten) layer beneath the crust, which is always moving due to heat from the core
• Core


  The hottest part of the Earth, made mostly of iron and nickel, with a liquid outer layer and a solid inner layer, which creates the Earth's magnetic field
• Parts of the Earth

  • Lithosphere
  • Hydrosphere
  • Biosphere
  • Atmosphere
• Lithosphere


  The rocky outer layer of the Earth, including the crust and uppermost mantle, made of minerals and forming the solid ground we walk on
• Hydrosphere


  All the water on Earth, from oceans and rivers to moisture in the air, covering most of the Earth's surface and playing a big role in regulating the planet's climate
• Atmosphere


  The layer of air surrounding the Earth, divided into different layers based on density, containing mostly nitrogen and oxygen, which keeps us warm, shields us from radiation, and helps distribute heat
• Biosphere


  All living organisms on Earth, from tiny bacteria to large animals, which depend on each other and their environment and play a role in shaping their surroundings
• These parts of the Earth interact with each other and influence the Earth's climate, geological processes, and the overall balance of life on our planet
• Characteristics of Earth necessary to support life

  • Water
  • Energy
  • Time
  • Recycling
• Water


  A liquid where molecules can interact, essential for life as we know it
• Energy


  Life needs energy to happen, such as sunlight for photosynthesis or chemicals from deep-sea vents