Question about relation between galaxies

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    Galaxies Relation
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Discussion Overview

The discussion revolves around the arrangement of galaxies in the observable universe, questioning the implications of the Big Bang theory on their formation and distribution. Participants explore concepts related to cosmology, galaxy formation, and the nature of the universe.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions why galaxies are structured as spirals with empty space between them, suggesting that the universe should appear more chaotic if it originated from a singular point.
  • Another participant clarifies that galaxies did not form during the Big Bang but rather after, as regions of slightly higher density collapsed over time to form galaxies and clusters.
  • The concept of the power spectrum is introduced to describe the distribution of matter in the universe, likening it to a foam structure with random overdensities.
  • One participant expresses a lack of understanding and acknowledges their naive concept of the universe, seeking further clarification.

Areas of Agreement / Disagreement

Participants exhibit differing views on the implications of the Big Bang theory for galaxy formation, with some asserting a more structured formation process while others suggest a more chaotic initial state. The discussion remains unresolved regarding the nature of galaxy distribution.

Contextual Notes

Limitations in understanding the initial conditions of the universe and the processes leading to galaxy formation are noted, with some assumptions about density and gravitational collapse remaining unexamined.

jon_pan
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why is it that galaxies are placed the way they are in our observable universe? as spirals of solar systems with empty space between them?

isn't it a concept of the big bang theory that, the universe was created from a point of singularity? And at an instant, all matter was ejected from that point? if so, then why does our universe appear the way it does? Should it not look more like scattered planets and stars exploding from a single point? which then eventually collapse back to that point?

to me it seams more reasonable that each galaxy is it's own, and not created relative to other galaxies. something like a big bang to create each galaxy.
 

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I'm not sure I understand your question, but remember that stars, planet, galaxies, etc. were not formed during the Big Bang, but well after. The basic picture is that you start with a universe that's nearly, but not completely uniform (mostly hydrogen gas). As time goes on, those parts of the universe that are slightly more dense than the others (overdensities) will start to collapse. In the current cosmological model, the first things to collapse will be tiny galaxies and star clusters. As time goes on, bigger and bigger objects collapse to form larger galaxies (like the spiral in your picture) and, eventually, galaxy clusters.

The relationship between the positions of galaxies is roughly described by the power spectrum. Think of the distribution of matter in the universe like a foam, with overdensities appearing randomly in space and the distribution of overdensities given by the power spectrum. Today, this distribution is a combination of the initial randomness in the nearly uniform hydrogen gas and the effects of gravitational collapse that occurred afterwards.
 
You have a naive concept of the universe, jon pan. ST took you through the basics.
 
Chronos said:
You have a naive concept of the universe, jon pan. ST took you through the basics.


i know, that's why I'm here asking question. thankx for the input
 

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