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Jul 29, 2023 · The Expanding Universe. Every model of the universe must include the expansion we observe. Another key element of the models is that the cosmological principle (which we discussed in The Evolution and Distribution of Galaxies) is valid: on the large scale, the universe at any given time is the same everywhere (homogeneous and isotropic). As a ...
- The Expanding Universe
- Models of The Expansion
- The Cosmic Tug of War
- Ages of Distant Galaxies
Every model of the universe must include the expansion we observe. Another key element of the models is that the cosmological principle (which we discussed in The Evolution and Distribution of Galaxies) is valid: on the large scale, the universe at any given time is the same everywhere (homogeneous and isotropic). As a result, the expansion rate mu...
Before astronomers knew about dark energy or had a good measurement of how much matter exists in the universe, they made speculative models about how the universe might evolve over time. The four possible scenarios are shown in Figure 2. In this diagram, time moves forward from the bottom upward, and the scale of space increases by the horizontal c...
We might summarize our discussion so far by saying that a “tug of war” is going on in the universe between the forces that push everything apart and the gravitational attraction of matter, which pulls everything together. If we can determine who will win this tug of war, we will learn the ultimate fate of the universe. The first thing we need to kn...
In the chapter on Galaxies, we discussed how we can use Hubble’s lawto measure the distance to a galaxy. But that simple method only works with galaxies that are not too far away. Once we get to large distances, we are looking so far into the past that we must take into account changes in the rate of the expansion of the universe. Since we cannot m...
The Expanding Universe. Every model of the universe must include the expansion we observe. Another key element of the models is that the cosmological principle (which we discussed in The Evolution and Distribution of Galaxies) is valid: on the large scale, the universe at any given time is the same everywhere (homogeneous and isotropic). As a ...
The Friedmann–Lemaître–Robertson–Walker (FLRW) model using Friedmann equations is commonly used to model the universe. The FLRW model provides a curvature of the universe based on the mathematics of fluid dynamics, that is, modeling the matter within the universe as a perfect fluid. Although stars and structures of mass can be introduced ...
Sep 26, 2017 · Philosophy of Cosmology. First published Tue Sep 26, 2017. Cosmology (the study of the physical universe) is a science that, due to both theoretical and observational developments, has made enormous strides in the past 100 years. It began as a branch of theoretical physics through Einstein’s 1917 static model of the universe (Einstein 1917 ...
- Christopher Smeenk, George Ellis
- 2017
The universe is all of space and time [a] and their contents. [10] It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from sub-atomic particles to entire galactic filaments. Since the early 20th century, the field of ...
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Redshift. This illustration simulates the redshift, or Doppler shift, that affects how light waves appear to us when the source of light is moving away. When we view galaxies from Earth, their light is shifted to the red side of the color spectrum, an indication that they are moving away from us. This is strong evidence for an expanding Universe.
