Orgins of atoms

Origin of Atoms

• Big Bang Theory

  • Atoms in our bodies originated from the stars, formed after the Big Bang.

  • Initially, only hydrogen, helium, and lithium atoms existed shortly after the Big Bang, while heavier elements were formed in stars.

• Timeline of Formation

  • Approximately 13.8 billion years ago: The universe began as a singularity, then underwent a rapid expansion (Big Bang).

  • Immediately after Big Bang: Only elementary particles (quarks and electrons) existed, no atoms.

  • After ~1 microsecond: Protons and neutrons formed as the universe cooled.

  • A few minutes later: Formation of light nuclei (H, D, He, Li) with a low density similar to air.

  • 400,000 years later: Matter clumped into stars; no further fusion occurred in the interim.

Formation of Elements in Stars

• After the Big Bang, stars formed where atoms combined to create heavier elements through fusion.

• The Big Bang theory gained credibility over time, transitioned from joke to established scientific theory due to accumulating evidence.

Evidence from Cosmic Observations

• Doppler Effect for Light:

  • Similar to sound, when light-emitting objects move towards us, light wavelengths compress (blue shift); moving away stretches the wavelengths (red shift).

  • Redshift indicates galaxies are moving away, evidencing universal expansion.

• Cosmic Microwave Background Radiation (CMBR):

  • Observations show nearly uniform background radiation correlating with the early dense and hot universe, allowing us to trace back to the Big Bang.

Gravitational Clumping and Star Formation

• As the universe cooled, tiny temperature fluctuations led to gravitational forces,

  • Matter clumped, raising temperatures further, which reignited nuclear fusion.

  • Stars formed from clumping of hydrogen and helium, initiating the production of heavier elements through nuclear reactions.

Nuclear Fusion in Stars

• Fusion Process: Hydrogen atoms fuse under extreme pressure and temperature to create helium, releasing vast amounts of energy.

  • Helium can further combine to create heavier elements (carbon, etc.).

  • Elements up to iron are formed in red giants; those heavier are produced in supernovae.

Stellar Generations and Earth's Formation

• Our Sun is a third-generation star, which formed from the remnants of previous supernova explosions.

  • Formation of the Solar System: A disk of matter formed around the Sun, leading to the creation of planets.

  • The presence of heavy elements (like iron) in the Sun indicates its origins from earlier stars.

Conclusion

• The atoms in our bodies are remnants of stars and cosmic events stretching billions of years ago, emphasizing the notion that we are made from stardust.