Is expansion a result of gravity?

In summary, the expansion of space time is a result of galaxies gravity. Dark energy is only postulated to explain the acceleration of the expansion of the universe.
  • #1
Is the expansion of space time a result of a galaxies gravity? If we take the classic trampoline example of space time I can explain what I mean. Each galaxy makes a dent in the trampoline, the more mass a galaxy gains the deeper the dent. Now if we take 2 bowling balls and place them far enough away on our trampoline that they don’t get stuck in each other’s dent then the space between them will stretch. As each galaxy gains more mass or fall into their own black hole then the space will continue to expand. It seems that the expansion of space time is a result of gravity. So why do we require dark energy?
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  • #2
You are stretching the analogy of bowling balls on trampolines a bit far here. To derive the expansion of the universe, we actually consider the universe to be completely homogeneous and isotropic. That is, there are no density fluctuations (galaxies, people, planets, stars, anything!). This is actually a fairly good assumption on very large distance scales. When we do this, and work through the maths, we simply find a dynamic universe, that is one that is in general expanding or contracting. And observational evidence shows, of course, that it is expanding.

Individual galaxies really have nothing to do with it. And dark energy is only postulated to explain the acceleration of the expansion of the universe.
  • #3
The rubber sheet analogy creates more confusion than it dispells. It is wonderful for the unwashed masses - not so good for those who think outside the box. The tripping block is math. Cosmology is impossibly complex for those lacking advanced math skills.
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  • #4
The Hubble universe constantly expands (all zones or spheres, some of which might be as small as the Planck length, do not necessarily contract after expansion) and inrushing energy feeds the spinning fractal. As in the vortex of a tornado, the spin draws in surrounding energy leaving a depleted zone around the vortex-sphere. This third vacuum, a surface-vacuum, attracts other fractals, while the constantly expanding (Hubble expansion) spinning surface repels them. The dynamic thus created between repulsive and attractive forces is the dynamic tension that underlies all matter. At this pre-particle, fractal level no thing exists that can interfere with the expanding and spinning vortex. Stability and permanence and inertia are created by Hubble expansion. Dark matter, and its theoretic “extra” gravity, may not be matter – but the temporary attenuation of the every part of the field.
  • #5

The expansion of space time is not solely a result of gravity. While gravity does play a role in the expansion of the universe, it is not the only factor. The concept of dark energy was introduced to explain the observed accelerated expansion of the universe. This expansion cannot be explained solely by the gravitational pull of galaxies, as it would cause the universe to collapse rather than expand. Therefore, there must be some other force at play, which we currently refer to as dark energy.

The trampoline analogy is a simplified representation of the concept of space time, and it does not fully capture the complexities of the universe. In reality, the expansion of the universe is influenced by multiple factors, including the distribution of matter and energy, the density of the universe, and the expansion rate of space time.

Furthermore, while gravity does cause the stretching of space between galaxies, it also causes the contraction of space within galaxies. This is why dark matter is necessary to explain the observed rotational speeds of galaxies, as it provides the necessary mass to counteract the gravitational pull and prevent galaxies from flying apart.

In conclusion, while gravity does contribute to the expansion of the universe, it is not the sole cause. The existence of dark energy is necessary to explain the current observations of the accelerated expansion of the universe. Further research and observations are needed to fully understand the mechanisms behind the expansion of space time.

1. What is expansion?

Expansion refers to the increase in size or volume of a system or object.

2. How does expansion occur?

Expansion can occur through various mechanisms, such as heating, cooling, or the presence of external forces.

3. Is expansion a natural phenomenon?

Yes, expansion is a natural phenomenon that is observed in many different systems, including the universe.

4. What is the role of gravity in expansion?

Gravity plays a crucial role in the expansion of the universe. It is the force that causes matter to attract and clump together, leading to the formation of galaxies and galaxy clusters. This gravitational pull also slows down the expansion of the universe.

5. Can gravity alone cause expansion?

No, gravity alone cannot cause expansion. In fact, the expansion of the universe is currently accelerating, which suggests the presence of a mysterious force called dark energy. Dark energy is thought to counteract the effects of gravity, contributing to the overall expansion of the universe.

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