astrooo

• Big Bang theory


  Currently accepted theory that explains the origin of the universe
• Big Bang nucleosynthesis

  1. The Big Bang is an expansion of space

  2. As the universe expands, it cools

  3. The more energetic the particles are, the higher the temperature will be

  4. The identity of the element depends on how many protons it has
• A quark-gluon plasma, a soup of particles known as quarks and gluons, condensed into protons and neutrons
• Stellar nucleosynthesis


  The process by which elements are created within stars by combining the protons and neutrons together from the nuclei of lighter elements
• Dark energy


  • A mysterious force that is causing the universe to expand at an accelerating rate
  • It makes up about 68% of the universe's total energy content
  • A form of energy that fills the vacuum of space and exerts a repulsive gravitational force
  • Characterized by its negative pressure, behaves opposite to ordinary matter
• Dark energy was discovered independently by two teams of astronomers (The supernova cosmology project led by Saul Perlmutter and High-Z Supernova search team led by Brian P. Schmidt and Adam Riess) in 1990's
• Type 1A supernova


  • "thermonuclear supernovae", occurs in a binary star system
  • One of the two stars must be a dwarf star
  • They are remarkably consistent in their peak brightness (used in studying the acceleration of the universe)
  • Their spectra exhibits redshift
• Redshift


  A phenomenon in which light from distant objects, such as galaxies or supernovae appears shifted towards longer (redder) wavelengths as a result of the expansion of the universe
• Expansion of the universe

  • 1929, Edwin Hubble discovered the universe was not static. He discovered the more distant the galaxy from us, the faster it appears to be descending into space (Hubble's law)
  • The universe is expanding uniformly in all directions
• Baryon Acoustic Oscillations are regular patterns in the distribution of galaxies, imprinted in the early universe due to acoustic waves traveling through hot and dense plasma
• Hubble's constant

  The rate at which the universe is expanding, 64.7+0.567.4+0.5 (km/s/Mpc)
• The Hubble Telescope was launched into low earth orbit by Space shuttle discovery in April 24, 1990. It was a joint project by NASA and the European Space Agency (ESA)
• Future implications of the expansion of the universe

  • Big crunch - if the influence of dark energy wanes over time, the universe's expansion may eventually slow down, reverse, and collapse in on itself
  • Big freeze - if dark energy continues to dominate the universe's expansion, leading to a big freeze where all matter and energy dissipate, and the universe becomes cold and empty
  • Big rip - An even more extreme is the big rip, where the dark energy's influence grows strong that is eventually tears apart all matter, including galaxies, stars and even atoms, leaving behind nothing but empty space
• Conditions immediately after the Big Bang

  • Extremely high temperatures
  • Rapid expansion
  • Primordial particles
  • Cosmic soup
• Expansion and cooling of the early universe

  1. Rapid expansion

  2. Dropping temperatures

  3. Quark-gluon plasma
• One second after the Big Bang

  • The four fundamental forces were unified into a single highly energetic force – gravity, electromagnetism, strong nuclear and weak nuclear
  • Subatomic particles like quarks, leptons and bosons were created in the intense heat and density of the early universe (building blocks of matter)
  • These fundamental particles interacted and combined, undergoing phase transitions as the universe rapidly expanded and cooled in the first moments after the Big Bang
• Nucleosynthesis was occurring minutes after the Big Bang
• 380,000 years after the Big Bang - recombination and the cosmic microwave background
• Gravitational Clumping


  In the early universe, tiny density fluctuations grew over billions of years, forming the first gravitational structures like galaxy clusters and superclusters
• Emergence of galaxies


  As matter coalesced, the first stars ignited, eventually assembling into the first primitive galaxies, the building blocks of the large-scale structures today
• The distribution of galaxies forms a vast cosmic web, with dense filaments and knots surrounding vast voids, shaped by the underlying dark matter structure of the universe
• Georges Lemaitre


  • Proposed that the universe was expanding, based on Einstein's theory of general relativity
  • It posits that massive objects (like stars, planets and galaxies) warp the fabrics of spacetime around them
  • Lemaitre referred to the initial singularity as the "primeval atom"
• Edwin Hubble

  His discovery of redshift in distant galaxies revealed that they were moving away from us
• George Gamow

  • Along colleagues Ralph Alpher and Robert Herman, predicted the cosmic microwave background (CMB) radiation
  • The CMB is a faint glow of radiation left over from the early hot phase of the universe
• Methods used to estimate the age of the universe

  • Calculating the expansion rate: Hubble constant
  • Oldest stars: the universe cannot be younger than its oldest stars. Scientist study the ages of the very first stars formed in cosmos. Globular clusters, dense stellar collections serve as cosmic timekeepers
• Big Bang theory


  Proposes that the universe began as a hot and dense point around 13.8 billion years ago and has been expanding and cooling ever since
• Limitations of the Big Bang theory

  • Flatness problem (geometry) - why the universe is so flat now when it started off curved
  • Horizon problem (temperature) - how distant parts of the universe become so similar in temperature
• Cosmic inflation theory

  • Developed around 1980 by Alan Guth, physicist and cosmologist
  • Proposes a period of extremely rapid (exponential) expansion of the universe during its first few moments. It increased the linear size of the universe by more than 60 "e-folds" of 10^26 in only a small fraction of a second
• Gregor Lemaitre referred "initial singularity" as primeval atom
• cosmic microwave background is a faint glow of radiation from an early hot phase of the universe.
• Unknown constituents is a form of energy that fills the vacuum of space and exerts a gravitational force
• Negative pressure is a characteristics of a dark matter where in it is an opposite of ordinary matter
• Hubble's law states that the distant objects such as galaxies appears to be descending faster in space
• Alan Guth is the Father of Cosmic inflation
• Cosmic inflation is the expansion of the universe during it's early years
• Quantum mechanics


  Describes how things works in a very small scale, deals with the concept of particles behaving like a wave, uncertainty and interaction between particles and energy
• Max Planck


  Founder and pioneer of Quantum mechanics
• Paul Dirac


  Formulated the quantum mechanics in terms of operators and introduced the Dirac notation
• Black body radiation


  A concept in physics that describes how all objects emit electromagnetic radiation when they are heated
• Atom


  Smallest unit of matter