The Acceleration and the density of galaxies

In summary, the Lambda-CDM model predicts that the density of galaxies will decrease over time due to the expansion of the universe. However, this does not mean that galaxies will completely disappear. They may become too dim to observe, but their light will still be present. The idea that galaxies will vanish due to accelerated expansion is a misconception, as pointed out by Krauss and supported by scientific research.
  • #1
mbond
41
7
In the Lambda-CDM model, the density of galaxies goes decreasing and should even vanish in the far future.

I would be grateful if someone could point me to a paper where this is calculated.
 
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  • #2
It is a simple inference from the number of galaxies in a comoving volume staying constant while the size of the comoving volume increases. This just has to do with expansion itself, accelerated expansion is not required.
 
  • #3
Also, as the universe expands, the density of galaxies decreases, but it never "vanishes".
 
  • #4
I mean the number of visible galaxies goes vanishing because of the Acceleration. This is told in the book "A universe from nothing" by L.. Krauss, chapter "Our miserable future". Is there a paper or a reference where this is calculated?
 
  • #5
mbond said:
I mean the number of visible galaxies goes vanishing because of the Acceleration. This is told in the book "A universe from nothing" by L.. Krauss, chapter "Our miserable future". Is there a paper or a reference where this is calculated?
This looks like a common misconception. Objects once seen never disappear. Apart from getting ever dimmer until eventually too hard to observe, that is. But the light is still there, reaching the observer.
Krauss has been guilty of wording this less-than-ideally in at least one other book - see e.g. this paper: https://arxiv.org/abs/astro-ph/0310808, example 13 in appendix B.
 
  • #6
mbond said:
I mean the number of visible galaxies goes vanishing because of the Acceleration. This is told in the book "A universe from nothing" by L.. Krauss, chapter "Our miserable future". Is there a paper or a reference where this is calculated?
In addition to Bandersnatch's comment, nearby galaxies aren't moving apart. It isn't immediately obvious that they would ever necessarily spread out far enough to be part of the fading Bandersnatch mentions.
 

1. What is the acceleration of galaxies?

The acceleration of galaxies refers to the rate at which the velocity of a galaxy changes over time. This can be caused by a variety of factors, such as the gravitational pull of nearby galaxies or dark matter.

2. How is the acceleration of galaxies measured?

The acceleration of galaxies can be measured through a variety of methods, including observing the redshift of light from distant galaxies, studying the rotation curves of galaxies, and using simulations and models based on gravitational theories.

3. How does the acceleration of galaxies affect the expansion of the universe?

The acceleration of galaxies plays a crucial role in the expansion of the universe. It is believed that the universe is expanding at an accelerating rate, and this is largely due to the gravitational pull of dark matter and dark energy on galaxies.

4. What is the relationship between the density of galaxies and their acceleration?

The density of galaxies and their acceleration are closely related. As the density of galaxies increases, so does their gravitational pull on each other, resulting in a higher acceleration. This can also lead to the formation of galaxy clusters and superclusters.

5. How does the study of the acceleration and density of galaxies contribute to our understanding of the universe?

Studying the acceleration and density of galaxies is crucial in understanding the structure and evolution of the universe. It helps us understand the role of dark matter and dark energy, the expansion of the universe, and the formation of large-scale structures. It also allows us to test and refine our theories of gravity and cosmology.

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