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Forestman
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How old was the universe after the big bang when galaxies started forming?
Well, we've seen galaxies out to about z=7, but yes, somewhere around 750 million years.mgb_phys said:The oldest ones observed around around 750Myr after big bang (z=5.5)
See http://antwrp.gsfc.nasa.gov/apod/ap011007.html for the picture of the Abell cluster
I'm not so sure that this is the case. The exact formation of the early galaxies has always been uncertain, just because the observations haven't been there.JuanCasado said:Is there any problem with the observation of mature, well-formed galaxies at higher redshift than previously expected?
Chalnoth said:I'm not so sure that this is the case. The exact formation of the early galaxies has always been uncertain, just because the observations haven't been there.
You should take all science-related news items with a huge grain of salt. They're often wildly distorted, sometimes just flat wrong.JuanCasado said:See for instance however:
http://www.spaceref.com/news/viewpr.html?pid=14524
Chalnoth said:You should take all science-related news items with a huge grain of salt. They're often wildly distorted, sometimes just flat wrong.
Okay.JuanCasado said:Well, these are not news, but a scientific article appeared in Nature:
Cimatti, A. et al., Nature 430 (2004) 184-187.
But observations have not yet established how, or even when, the massive spheroidals formed
Chalnoth said:A good rule of thumb when it comes to stuff like this is that simulations not backed by observation are often wrong.
That wasn't my point. My point was that I rather doubt that most physicists were actually surprised by the news that the simulations were entirely accurate.JuanCasado said:The nature paper is an observational report, contrarily to what you seem to suggest...
The Big Bang theory is a widely accepted scientific explanation for the origins of the universe. It states that about 13.8 billion years ago, the entire universe was contained in a single point of infinite density and temperature, known as a singularity. Suddenly, the singularity began to rapidly expand and cool, resulting in the formation of matter, energy, space, and time. This expansion continues to this day and is the reason why the universe is constantly expanding.
According to current scientific estimates, the universe is approximately 13.8 billion years old. This age is determined by measuring the rate of expansion of the universe and extrapolating backwards to the point of the Big Bang. This age is also supported by other evidence such as the cosmic microwave background radiation and the abundance of elements in the universe.
There are multiple lines of evidence that support the Big Bang theory. These include the observed expansion of the universe, the cosmic microwave background radiation, the abundance of light elements, and the distribution of galaxies. Additionally, the theory has been tested and validated through various experiments and observations, providing further evidence for its validity.
After the Big Bang, the universe was filled with a hot, dense plasma of particles. As the universe continued to expand and cool, these particles began to clump together due to gravity, forming the first galaxies. These early galaxies were small and irregular in shape, unlike the spiral and elliptical galaxies we see today. Over time, through processes such as mergers and star formation, these galaxies evolved into the diverse structures we see in the universe today.
While the Big Bang theory is the most widely accepted explanation for the origins of the universe, there are alternative theories that have been proposed. These include the Steady State theory, which suggests that the universe has always existed in a constant state, and the Cyclic model, which proposes that the universe goes through cycles of expansion and contraction. However, these theories have not been supported by the same level of evidence as the Big Bang theory and are not widely accepted by the scientific community.