Why does the expansion of space in a uniform universe only push outward?

  • Thread starter Farahday
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In summary, the expansion of space in an isotrophic and homogeneous cosmos is not necessarily outward. It could be inward and still maintain the same symmetry. Isotropy means that things look the same in all directions, while homogeneity means that things look the same in all places. As long as space is uniformly expanding or contracting, it will preserve this symmetry.
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Farahday
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In an isotrophic and homogeneous cosmos, why would the expansion of space be specifically be vectored outward. Should it not also push galaxies together?
 
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The outward nature of the expansion is (in this case) unrelated to the isotropy and homogeneity of the universe. It could be either inward or outward, and still both isotropic and homogenous.

Remember that isotropic means the same in all directions (i.e. no matter which direction you look, things look the same); and homogenous means the same in all places (i.e. no matter where you go, things look the same). As long as space was uniformly expanding or contracting, it would preserve the same symmetry.
 

1. What is expansion?

Expansion refers to the increase in size or volume of an object or system. This can occur due to various factors such as heat, pressure, or chemical reactions.

2. What causes expansion?

The main cause of expansion is an increase in temperature. When an object or substance is heated, its particles gain energy and move faster, causing them to spread out and take up more space. Expansion can also occur due to changes in pressure or the introduction of new substances.

3. Why is expansion important in science?

Expansion is important in science because it affects various natural phenomena and human-made systems. For example, the expansion of water when frozen can cause pipes to burst, and the expansion of air when heated causes weather patterns. Understanding expansion also helps scientists develop new materials and technologies.

4. How is expansion measured?

Expansion can be measured using various units, such as length, volume, or density. The most common unit for measuring expansion is the coefficient of thermal expansion, which is expressed as a change in length or volume per degree of temperature change.

5. Can expansion be controlled or prevented?

In some cases, expansion can be controlled or prevented by using materials with low coefficients of thermal expansion or by designing systems that can accommodate expansion. However, in other cases, such as the expansion of the universe, it is a natural and uncontrollable process.

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