Are Flat, Coplanar Orbits Only Found in Spiral Galaxies?

In summary, Inflation is a hypothesized PART of the expansion from a hot dense state. It occurred (IF it occurred) in a very tiny fraction of a second, a tiny fraction of a second after the singularity, and caused an unbelievably massive expansion of the universe. By human standards this would have been for all practical purposes "instantaneous" however, as a scientific description of what happened, "instantaneous" is nonsense.
  • #1
Sastronaut
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Hey PF! Have two questions here for everyone. Recently had a professor define the The Big Bang as "the expansion and cooling of the universe from an originally hot and dense state", but is this correct? To me it sounded more like the description of cosmic inflation...thoughts?

Additionally, was recently reading about galaxy types and star orbits. Which types of galaxies do you think astronomers would find stars that orbit in flat, coplanar orbits? My thought is solely spiral galaxies, but is that right? Do irregular or elliptical contain stars that orbit in such a manor? I didn't think irregular because i thought orbits would be all over place since irregular galaxies are created through collisions or galaxy's interacting and the resulting gravitation interaction would skew star orbits.


Thanks PF
 
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  • #2
That is an excellent description of the big bang, which is indeed a theory that describes the evolution of the universe as an expansion from a hot dense state. Why do you think it is not?
 
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  • #3
Because i have read that the (rapid) expansion of the universe is a descriptive for inflation and i have also seen the big bang theory defined simply as the instantaneous expansion of space and time...
 
  • #4
Sastronaut said:
Because i have read that the (rapid) expansion of the universe is a descriptive for inflation and i have also seen the big bang theory defined simply as the instantaneous expansion of space and time...

Any description that says it was an instantaneous expansion is utterly wrong

Inflation is a hypothesized PART of the expansion from a hot dense state. It occurred (IF it occurred) in a very tiny fraction of a second, a tiny fraction of a second after the singularity, and caused an unbelievably massive expansion of the universe. By human standards this would have been for all practical purposes "instantaneous" however, as a scientific description of what happened, "instantaneous" is nonsense.

Inflation is not proven but it explains more than any other theory about the characteristics of the very early part of the expansion.
 
  • #5
Phinds thank you for your help that makes much more sense now!
 

1. How do stars orbit around each other?

Stars orbit around each other due to the force of gravity. The larger the mass of the star, the stronger its gravitational pull, causing other stars to orbit around it. This is similar to how planets orbit around the sun.

2. What is the difference between a stable and an unstable star orbit?

A stable star orbit is one in which the stars remain in a relatively constant position in relation to each other. This is usually the case for stars that are far apart from each other. An unstable star orbit is one in which the stars are close together and their gravitational forces cause them to constantly change their positions and orbits around each other.

3. How does the Big Bang theory explain the formation of stars?

The Big Bang theory states that the universe began as a singularity and expanded rapidly, eventually leading to the formation of galaxies, stars, and other celestial bodies. The first stars were formed from the gas and dust that were created during the Big Bang. As these stars aged, they fused hydrogen and other elements, creating heavier elements that were eventually used to form new stars.

4. Can stars change their orbits?

Yes, stars can change their orbits over time due to various factors such as interactions with other stars, the presence of a massive object like a black hole, or the gravitational pull of nearby galaxies. However, these changes happen over long periods of time and are not noticeable to the human eye.

5. What evidence supports the Big Bang theory?

There are several pieces of evidence that support the Big Bang theory, including the cosmic microwave background radiation, the abundance of light elements in the universe, and the redshift of galaxies. Additionally, the theory has been tested and supported by numerous scientific experiments and observations.

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