Lesson-1-The-origin-of-the-Universe.docx

**Lesson 1: THE UNIVERSE AND ITS ORIGIN** **[Baryonic matter-]** "ordinary" matter consisting of protons, electrons, and neutrons that comprises atoms, planets, stars, galaxies, and other bodies **[Dark matter-]** matter that has gravity but does not emit light **[Dark energy-]** a source of anti...

**Lesson 1: THE UNIVERSE AND ITS ORIGIN** **[Baryonic matter-]** "ordinary" matter consisting of protons, electrons, and neutrons that comprises atoms, planets, stars, galaxies, and other bodies **[Dark matter-]** matter that has gravity but does not emit light **[Dark energy-]** a source of anti-gravity, a force that counteracts gravity and causes the universe to expand **[Protostar]**- an early stage in the formation of a star resulting from the gravitational collapse of gases **[Thermonuclear reaction-]** a nuclear fusion reaction responsible for the energy produced by stars **[Main Sequence Stars-]** stars that fuse hydrogen atoms to form helium atoms in their cores; outward pressure resulting from nuclear fusion is balanced by gravitational forces **[Light years-]** a unit of length used to measure astronomical distance **THE UNIVERSE** -The Universe is at least **13.8 billion years old** while the Solar System is at least **4.5-4.6 billions of years old** **-** Comprises all space and time, and all matter and energy in it - Made up of **[4.6%baryonic matter]**(ordinary matter consisting of protons, electrons and neutrons: atoms, planets , stars, galaxies, nebulas, and other bodies) - **[24% cold dark matter]** (matter that has gravity but does not emit light) **-Dark matter** can explain what may be holding galaxies together for the reason that the low total mass is insufficient for gravity alone to do so - **[71% dark energy]**(a source of anti-gravity) - It is also made up of **[Hydrogen]**, **[helium]**, and **[Lithium]** **GALAXY**- a cluster of billions of stars \- Diameter is at least **91 billion light years** **THEORIES THAT PRECEDED THE BIG BANG THEORY OF THE ORIGIN OF THE UNIVERSE** - Ancient Egyptians believed in many gods and myths which narrate that the world arose from an infinite sea at the first rising sun. - The Kuba people of Central Africa tell the story of a creator god Mbombo (or Bumba) who, alone in the dark and water-covered Earth, felt an intense stomach pain and then vomited the stars, sun, and moon - In India, there is the narrative that gods sacrificed Purusha, the primal man whose head, feet, eyes, and mind became the sky, earth, sun, and moon respectively. - The monotheistic religions of Judaism, Christianity, and Islam claim that a supreme being created the universe, including man and other living organisms. - **STEADY STATE MODEL** - **THE PRIMORDIAL UNIVERSE** - **CYCLICAL OR OSCILLATING UNIVERSE** - **PTOLEMAIC UNIVERSE** - **EINSTEINIAN** **UNIVERSE** - **" THE BIG BANG THEORY"** - **The Big Bang Theory has withstood the tests for expansion:** - **" THE RED-SHIFT"** - **Redshift** refers to a phenomenon in astronomy where the light emitted by an object in space, such as a star or galaxy, appears to be shifted toward longer wavelengths, which corresponds to the red end of the electromagnetic spectrum. - This is primarily observed in the context of the Doppler effect, which is the change in the frequency or wavelength of a wave as perceived by an observer moving relative to the source of the wave. - In the case of redshift, it usually occurs because an object in space is moving away from an observer (like Earth). As the object moves away, the light it emits is stretched, causing its wavelength to increase. - This stretching of the light waves results in a shift towards the longer-wavelength, lower-frequency, and \"redder\" part of the spectrum. - **"COSMIC MICROWAVE BACKGROUND (CMB)"** - **Evolution of the Universe according to the Big Bang Theory** - From time zero (13.8 billion years ago) until 10ˉ¹³ second later, all matter and energy in the universe existed as a hot, dense, tiny state. - It then underwent extremely rapid, exponential inflation until 10ˉ³² second later after which and until 10 seconds from time zero, conditions allowed the existence of only quarks, hadrons, and leptons. - Then, Big Bang nucleosynthesis took place and produced protons, neutrons, atomic nuclei, and then hydrogen, helium, and lithium until 20 minutes after time zero when sufficient cooling did not allow further nucleosynthesis. - From then on until 380,000 years, the cooling universe entered a matter-dominated period when photons decoupled from matter and light could travel freely as still observed today in the form of cosmic microwave background radiation. - As the universe continued to cool down, matter collected into clouds giving rise to only stars after 380,000 years and eventually galaxies would form after 100 million years - From 9.8 billion years until at present, the universe became dark-energy dominated and underwent accelerating expansion. - At about 9.8 billion years after the Big Bang, the solar system was formed.