Formation of the universe pt. 1

Formation of the Universe and the Solar System

• Overview: Neil deGrasse Tyson's "Astrophysics for People in a Hurry" provides insights into cosmic history.

• Cosmic Microwave Background (CMB):

  • Detected by WMAP (Wilkinson Microwave Anisotropy Probe).

  • The CMB represents the cooled remnant of the first light emitted after the Big Bang.

  • This radiation has cooled and weakened but is visible in the microwave spectrum.

Evidence Supporting the Big Bang Theory

• Three key lines of evidence:

  1. Galaxies are receding:

     • Galaxies recede at speeds dependent on their distance from Earth, explained by Hubble’s Law.

  2. CMB Radiation:

     • Remnants of free radiation from the period of non-ionized elements.

  3. Element Formation:

     • Formation of hydrogen, helium, deuterium, lithium, and beryllium shortly after the Big Bang; heavier elements formed later.

     • The cosmic abundances of elements are consistent with predictions from the Big Bang theory.

The Big Bang, Nucleosynthesis & Solar System Formation

• Big Bang Event: Occurred approximately 13.798±0.037 billion years ago.

• Solar System Formation:

  • Estimated to have formed around 4.57 billion years ago.

  • The time span between the Big Bang and solar system formation is around 9 billion years.

• Nucleosynthesis Process:

  • Began shortly after the Big Bang, forming elements through nuclear reactions.

  • Stars formed, conducting nuclear fusion and creating elements up to iron (Fe) and nickel (Ni).

  • Heavier elements formed from supernova explosions.

• The Sun is a third-generation star, indicating its formation from previously exploded stellar material.

• Solar System's Origin:

  • Formed from a collapsing molecular cloud, leading to a protoplanetary disk.

Cosmic Processes and Structure

• Cosmic Inflation and Nucleosynthesis: Account for the formation of light and heavy elements during early universe evolution.

Absorption Spectra and Element Composition

• Absorption Spectra:

  • When an element absorbs specific light frequencies, it creates a unique spectrum akin to a fingerprint for each element.

  • The interaction between the frequency of light and an element's electrons shows quantized energy levels.

• Sun’s Composition:

  • Approximately 73% hydrogen and 25% helium by mass; other elements contribute less than 2%.

Observational Astronomy Techniques

• Doppler Shift:

  • A moving source changes the frequency of emitted radiation, affecting perceived color (redshift and blueshift).

  • As galaxies move, their light shifts toward red or blue based on movement relative to Earth.

• Spectrogram Analysis:

  • Stars and galaxies produce identifiable absorption bands on spectra which can be analyzed for distance based on redshift.

• Hubble’s Law:

  • Observations show that the velocity of receding galaxies increases with distance, indicating an expanding universe.

Distance Measurement Techniques

• Parallax Method:

  • Utilizes Earth's orbit to measure the distance of nearby stars based on observable angle changes.

  • Parsecs: A distance unit where one astronomical unit subtends an angle of one arcsecond; 1 parsec = 3.26 light years.

The Expanding Universe

• Hubble’s Constant:

  • Indicates the rate of expansion of the universe, generally expressed in km/s/Mpc.

  • Current estimates range from 67.66 to 72.5 km/s/Mpc.

• Analogy of Expansion:

  • Raisin bread and balloon analogies illustrate how galaxies move away from each other in an expanding universe without a defined center.

  • The universe's expansion is accelerating, with distant galaxies receding faster.

Conclusion: Understanding the Universe

• The evidence corroborates the Big Bang theory leading to cosmic expansion as predicted by George Lemaitre in 1927.

• The increase in recession velocity with distance supports a uniformly expanding universe.