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What did we first believe about the universe?
- God put us at the centre
- There are some objects that move in the sky too, these move between the stars and are known as planets
Who changed the original misconceptions about the earth?
- Nicolas Copernicus
- Argued the sun was at the centre and the earth and other planets orbited it
- Persecuted by the catholic church and suppressed
- Giordano Bruno theorised that space was an infinite void rather than a finite one with planets flying around between stars so the Catholic church decided to set him on fire
Who was responsible for major improvements in astronomy?
- Galileo Galilei
- Helped to improve and perfect the telescope
- Kept under house arrest by the church until death (they were proper dicks)
- Only 400 years later were his theories recognised as true by the Vatican (1990)
How can we assess the composition of stars?
- Using astronomical spectroscopy
- Prisms within the telescope split light allowing us to measure the spectrum of electromagnetic radiation from celestial bodies
- This allows us to derive properties such as temperature, chemical composition, mass luminosity and even relative motion using doppler shift measurements
What happened in the singularity phase of the big bang?
The universe was condensed into a single tiny point with an infinite mass and infinite temperature signalling a breakdown of relativity and the laws of physics (Hawking & Ellis, 1973)
What happened in the inflation and baryogengesis phase of the big bang?
- The universe very rapidly expanded and cooled
- It was filled uniformly and omnidirectionally with an incredibly high energy density
- Almost instantly after this, cosmic inflation occurred in which the universe expanded infinitely and consisted of a quark-gluon plasma (a theoretical state at high temperatures consisting of free quarks and gluons) and basic elements such as hydrogen
- At an unknown point the baryon (quantum) number of the universe was violated meaning more quarks and leptons existed than antiquarks and antileptons meaning there is more matter than antimatter
What the hell are quarks, gluons and leptons?
- Quark: a fundamental constituent of matter, combined to form hadrons (more stable composite particles such as protons and neutrons)
- Gluon: acts as the exchange particle between quarks (like photons in electromagnetic attraction between atoms or some shit, whatever)
- Lepton: basic particle that does not undergo strong interactions and is found in atoms. An example of a lepton is an electron, that orbits protons and neutrons to form atoms
What happened during the cooling phase of the big bang?
- Quarks and gluons cooled, collided and formed baryons such as protons and neutrons
- A few minutes after the expansion protons and neutrons began colliding to form deuterium (an isotope of hydrogen) and helium nuclei but most was left unreacted as hydrogen
- About 379,000 years later nuclei and electrons started combining to form atoms (mostly hydrogen)
What happened in the structure formation phase of the big bang?
- When the universe was roughly 600,000,000 years old clouds of denser clouds of matter such as hydrogen started getting pulled together, increasing the density and temperature and forming gas clouds, stars and galaxies
- When the energy required to fuse helium atoms started to fall they started to fuse to form larger molecules
- Stars assembled together protons and neutrons, fusing them until supernova occurred where they had enough energy to fuse a greater number of them to create the bigger elements
- Elements created during the supernovas were dispersed, gathered to form clouds, then condensed and collapsed to form planets
What is the universe composed of (roughly)?
- 75% hydrogen
- 24% helium
- Trace amounts of elements such as lithium
What is the composition of a hydrogen nucleus?
What is the composition of a helium nucleus?
What is the composition of a lithium nucleus?
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