";s:4:"text";s:2700:" The total mass of ordinary matter in the universe can be calculated using the critical density and the diameter of the observable universe to be about 1.5 × 10 53 kg. Cram.com makes it easy to … Study Flashcards On Glencoe Earth Science Chapter 31 The Galaxies and the Universe at Cram.com. In November 2018, astronomers reported that the extragalactic background light (EBL) amounted to 4 × 10 84 photons. If the Hubble constant is around 20 kilometers/second per million light-years, the critical density is about 10 –26 kg/m 3. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The other dominant contributor is Dark Matter, and a small amount is due to atoms or baryonic matter .
At this density the universe still expands forever, but the expansion speed goes asymptotically to zero as time goes on. In this universe, there is sufficient mass in the universe to slow the expansion to a stop, and then eventually reverse it. Mass also has an effect on the overall geometry of the universe. Dark Energy makes up 72% of the total mass-energy density of the universe.
Let’s see how this value compares with the actual density of the universe. In 1998 two teams of astronomers announced that distant, z~1 type Ia supernovae were slightly too faint than model predictions of an expanding (yet slowing) universe.
Closed universe (top), open universe (middle), and flat universe (bottom). And if the critical density was just right, the Universe’s expansion goes on forever, but it’s always slowing down, reaching a dead stop in an infinite amount of time. Another way to measure Ω is to do so geometrically by measuring an angle across the observable universe. The actual value for critical density value is measured as ρ critical = 9.47×10 −27 kg m −3. NASA. There is a critical density between collapse and expansion. Given the present value of the Hubble constant, that critical density is: 9 × 10−27 kg/m3 This is about five hydrogen atoms per cubic meter. The density of matter and energy in the universe determines whether the universe is open, closed, or flat. Quickly memorize the terms, phrases and much more. If the density of the universe is greater than the critical density, then gravity will eventually win and the universe will collapse back on itself, the so called “Big Crunch”, like the graph's orange curve. Critical Density of the Universe From these values, within experimental error, the universe seems to be flat. Start studying 201: Selecting the Right Shows: The Critical Decision.