The Big Bang Theory What is the Big Bang Theory? Big Bang Theory explains that the universe is expanding, and if we reverse the expansion, there must have been a singularity where everything is together. The sudden separation and expansion of the singularity is called the Big Bang. Evidence There are 3 main evidences to the Big Bang: Red Shift, Cosmic Microwave Background Radiation (CMBR), and Elemental Abundances Red Shift Red Shift is a phenomenon where light is shifted towards the red of the light spectra the further away the source of the light is. It is seen that all observable galaxies are red shifting from us, meaning that the universe is expanding. The "reddest" in the spectra are known as microwaves Cosmic Microwave Background Radiation (CMBR) CMBR is the microwaves that are detected all around us. This shows that that the universe has expanded so far since the big bang that the radiation of the big bang has redshifted so far to the point where it turned to microwaves. This was discovered by a satellite called COBE. The pink spots on the left picture are the microwaves. Elemental Abundnces After the Big Bang, the universe was too cold for fusion, therefore atoms were broken up to one of the lightest elements, Hydrogen and Helium. There are about 70% H, 29% He, and 1% everything else, in the universe. Limitations of the Big Bang There are some problems that come with the Big Bang Theory, which are called the Limitations of the Big Bang. The Flatness Problem: WMAP (A satellite) has determined that the geometry of the universe is flat, while the Big Bang Theory contradicts this and states that curvature grows with time The Horizon Problem: The distance in the region of space is so big that the light-years of the distance between space exceed the age of the universe. Big Bang Theory (cont) The Inflation Theory The inflation theory theorizes that there was a small period after the Big Bang where the universe expanded rapidly called the Inflation, unlike the gradual expansion currently. How this solves the Limitations The Flatness Problem: The universe had expanded so much during the Inflation, that it became perceived as "flat" As you can see from the picture, the circle is the Universe, round. (not to scale) if we zoom in and in, (the stars are markers), by the time we reach the purple star, the terrain seems flat. This is like the universe: The universe is so big that in the field of our view (as far as we can go), it will look flat because the universe is inflated so much. Inflation stretches any initial curvature of the universe to near flatness. How it solves the Horizon Problem Because the Universe had expanded rapidly in such as small period of time, it explains why there are larger light-years of distances of space between galaxies. Structure of the Universe There is some speculation on how the universe is shaped. There are 3 ways it could be shaped, Closed, Flat, or Open. Fun Fact Dark Energy takes up 73% of the universe, and Dark matter takes up 23%, while atoms, or regular things we see such as stars only take up 4.6%. Astounding! Dark Matter Dark Matter is matter that does not emit any radiation, nor can we see it, but it does have gravity. Dark Energy Dark Energy is a mysterious energy that pushes the universe faster and faster. This is why the expansion of the universe is slower a few billion years ago than now. Sources NASA. (n.d.). WMAP inflation theory. NASA. Retrieved September 16, 2021, from https://map.gsfc.nasa.gov/universe/bb_cosmo_infl.html. NASA. (n.d.). WMAP big BANG CMB Test. NASA. Retrieved September 16, 2021, from https://map.gsfc.nasa.gov/universe/bb_tests_cmb.html. NASA. (n.d.). Wmap- big bang expansion: The hubble constant. NASA. Retrieved September 16, 2021, from https://map.gsfc.nasa.gov/universe/bb_tests_exp.html. NASA. (n.d.). WMAP- content of the universe. NASA. Retrieved September 16, 2021, from https://map.gsfc.nasa.gov/universe/uni_matter.html. Greicius, T. (2016, August 31). The universe comes into sharper focus. NASA. Retrieved September 16, 2021, from https://www.nasa.gov/mission_pages/planck/multimedia/pia16874.html. E=mc 2
