From Quark Soup to Atoms: The Universe’s First Three Minutes скачать в хорошем качестве

From Quark Soup to Atoms: The Universe’s First Three Minutes

#FirstThreeMinutes #BigBang #Nucleosynthesis #CosmicMicrowaveBackground #EarlyUniverse #Cosmology #Astrophysics #QuarkSoup #Universe #SpaceScience Today, we’re delving into the universe’s first three minutes. This lecture is inspired by Stephen Weinberg’s book, “The First Three Minutes,” an excellent read on the topic. We’ll be exploring the elements of the Big Bang that predict the existence of the cosmic microwave background (CMB), rooted in nuclear physics experiments from the 1940s. Big Bang Cosmology Foundations: Starting with the principles of homogeneity and isotropy, general relativity suggests we can apply laws of physics universally. Observations of redshift show galaxies rushing away, indicating a smaller, hotter, denser universe in the past. This leads us to thermodynamics and the prediction of the CMB. Nuclear Synthesis and Initial Elements: As we move back in time, the universe reaches a point where it’s as hot as the center of a star, triggering nucleosynthesis—similar processes occurring within stars. The universe today is cold and low-density, but in the past, it was hot and dense, proving an early hot phase. Formation of Helium and Hydrogen: We observe the universe and see that stars have a minimum of 25% helium, hinting at an origin predating stars. Understanding the universe’s different particles—protons, neutrons, photons, and electrons—helps explain their roles in early nucleosynthesis. The Standard Model of particle physics, with its six quarks and six leptons, provides a framework for the particles’ behavior. Understanding Particle Physics: Quarks and leptons, along with force carriers like photons, gluons, and the Higgs boson, form the universe’s fundamental particles. Quarks combine to form protons and neutrons, held together by gluons. The Higgs boson, confirmed in 2012, imparts mass to these particles. The Universe’s Timeline and Expansion: Going back in time, the universe was hotter and denser. Around 45,000 years after the Big Bang, energy density was dominated by radiation. As the universe cooled, protons and neutrons formed, leading to nucleosynthesis similar to processes in the sun. By three minutes post-Big Bang, temperatures allowed for hydrogen fusion, forming helium. Deuterium Formation and Cooling Universe: Deuterium, a key observation, formed in the cooling universe, providing evidence of primordial nucleosynthesis. The universe at three minutes old had a specific balance of hydrogen, deuterium, and helium. As the universe expanded and cooled further, these elements remained consistent. Evidence of Primordial Nucleosynthesis: Observations show a consistent helium abundance matching predictions from nucleosynthesis. Tiny amounts of deuterium and other elements support the theory. The balance of photons to matter, fixed in the early universe, can be observed in the CMB. Long-Term Effects and Cosmic Microwave Background: Post-nucleosynthesis, the universe was a fog of particles until cooling allowed atoms to form, leading to the epoch of recombination. The CMB, a relic of this era, gives insight into the early universe’s conditions, proving the Big Bang model. yThe universe’s first three minutes are critical to understanding nucleosynthesis and the formation of elements. Observations match predictions, with the CMB providing key evidence. Next time, we’ll discuss the earliest epochs of cosmic time and the formation of galaxies and cosmic structures. See you then! The First Three Minutes: A Modern View of the Origin of the Universe by Weinberg: http://www.amazon.com/The-First-Three... Cosmology: A Very Short Introduction: by Coles: http://www.amazon.com/Cosmology-A-Ver...