Lecture 1 GEp

The Big Bang Theory

• The Big Bang theory proposes the universe began from a concentrated point of matter and energy and expanded violently.
• The universe began as a single atom-sized point, expanding rapidly.
• All matter and space originated from this single, dense energy point in an instant.
• The theory lacks concrete evidence.

Cosmological Principals and General Relativity

• The formation of the universe involved a combination of cosmological principles and general relativity.
• The universe's age is estimated at approximately 14 billion years (13.7 billion years).
• The concept of nucleosynthesis (Alpher-Bethe-Gamow, 1946) is a part of this formation.

Hubble's Law

• Introduced in 1929.
• Hubble's Law establishes a relationship between the distance of galaxies and their speed of recession.
• The farther away a galaxy is, the faster it's moving away, showcasing the universe's expansion.
• Redshift is a phenomenon where light from distant objects is shifted to longer wavelengths, indicating their movement away

Supporting Evidence for Big Bang

• Universal Expansion (Red Shift) and Hubble's Law: Observations confirm galaxies are moving away from each other, supporting an expanding universe.
• 3-degree Background Radiation: Cosmic Microwave Background Radiation (CMB), measured in 1965, aligns with predictions regarding radiation from the early universe.
• Quasars: These extremely bright objects located far from Earth provide evidence of the early universe.
• Abundance of Lighter Elements: Observed ratios of lighter elements (Li, H, He, Be) in the universe match Big Bang predictions.
• Stellar Formation and Evolution: Observations of stars' life cycles and their movement across the cosmos aligns with the theory.
• Speed of Light and Stellar Distances: Knowing the speed of light allows calculations about objects in the universe, providing insight into those far, far away.

Arguments Against the Big Bang Theory

• Too Much Energy: The initial conditions of a vacuum and the law of conservation of energy present a challenge to the theory. A vacuum by definition has no energy, but the Big Bang theorizes a vacuum with energy.

• Complex Theory and Too Early: Some argue the theory struggles to explain the swift formation of complex structures within the timeline predicted. An estimate puts formation time at 100 billion years to include large structures.

New Theory (The Space-Time Continuum)

• According to Einstein the universe can exist in three forms:
  • Closed: If travelling far enough, you will return to the starting point. The universe slows, stops, & reverses to a new "Big Bang"
  • Open: The universe expands indefinitely
  • Flat: When travelling in a straight line, one will not return to their starting point, matching recent observations.

Timing of Big Bang

• This section provides a timeline of key events following the Big bang, from the initial moments to the formation of stars, and galaxies.

3 minutes after Big Bang

• The universe expands tremendously, growing beyond the size of a grapefruit.
• Einstein's E=mc² equation illustrates how energy transforms into matter.
• Energy forms into matter, producing protons, neutrons, and electrons.

Chemical Elements Formation

• About several hundred thousand years after the Big Bang, atoms form, primarily hydrogen with small amounts of helium.
• 75% of the early universe consisted of hydrogen, and 25% of helium. This ratio continues today.

About 200-400 million years After Big Bang

• First stars and galaxies began to form

What is a Galaxy?

• A galaxy is a large collection of stars, gas, and dust held together via mutual gravitational forces.
• Galaxies range from a few million to tens of trillions of stars, with varying amounts of interstellar matter (gas and dust)

Galaxy Formations

• This section provides illustrations depicting the formation and evolution of galaxies over a significant period of time.

The Center of the Milky Way Galaxy

• Illustration of the Milky Way galaxy showing a region with high dust density and the supermassive black hole at its center.

About 4.6 billion years ago

• The solar system formed; our sun is a key part of the solar system.

Earth

• Our planet, Earth,

###Summary Big Bang Timeline

• The summary provides a timeline of essential events from the Big Bang to the formation of Earth. It details the transition from raw energy to matter, atoms, stars, galaxies, and finally our solar system and the planet Earth.