Looking back in time to the Big Bang

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The discussion centers on the concept that the Big Bang cannot originate from a singular point, as the universe appears uniform in all directions. Observers looking in opposite directions can see the universe's earliest state, suggesting the Big Bang is "spread out" rather than localized. The conversation highlights the limitations of observation, noting that we can only see light that has traveled up to 46 billion light-years due to the universe's expansion over approximately 13.7 billion years. It emphasizes that all matter, including Earth, originates from the Big Bang, which has led to a uniform distribution of matter throughout the universe. The analogy of sound waves spreading from a point source is used to illustrate how the Big Bang's effects can be observed from any location in the universe.
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If the universe is uniform no matter in what direction you look , then looking in two opposite directions, two observers, if each looks far enough will see the Universe at its earliest time -- The Big Bang. Therefore, the event of the Big Bang cannot be from a point singularity. It does not exist in anyone (singular) direction, but can be observed in any direction you cast your gaze. Like the electron, then, the Big Bang must be "spread out" in an "orbit" around all that is. The concentration of matter around the time of the Big Bang "spread in all the furthest directions that you can see might be what causes the tug of matter toward it and away from any present observer. Couldn't it be that the universe is actually contracting outward toward the Big Bang instead of expanding as if away from a center?
 
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poeteye said:
If the universe is uniform no matter in what direction you look , then looking in two opposite directions, two observers, if each looks far enough will see the Universe at its earliest time -- The Big Bang. Therefore, the event of the Big Bang cannot be from a point singularity.

Can you explain that? A sound wave originates from some source which we usually consider to be a point source, yet the wave front spreads out in all directions. You can observe it from anywhere.

Also, note that "looking far enough" is a nice statement but without physical meaning: we can only see so far as the light has been able to travel so far.
 
CompuChip said:
... we can only see so far as the light has been able to travel so far.

That's right! Good point. We can only see matter which is 46 billion lightyears away from us, at present.

Because in the whole age of expansion (estimated 13.7 billion years) that is the farthest light has been able to reach.

It's good to think about those numbers and to help visualize you can try some of the basic visualization stuff in this sticky thread:
https://www.physicsforums.com/showthread.php?t=261161

It's basic cosmo one----if you have any questions or don't understand, just ask.

Keep in mind that all matter, including Earth rocks and our bodies, derives from what issued from the Bang.
And the farthest matter we can see----the stuff which is now 46 billion lightyears away at present---has by now presumably evolved into stars and galaxies and planets looking pretty much like our local neighborhood.
The assumption of uniformity covers them as well as us. The heavens to them presumably look very similar to ours. They too are uniformly surrounded, in all directions, by stars and galaxies.
The uniformity that poeteye mentioned means that all space is uniformly filled with matter, more or less evenly distributed----as far as we know there is no space outside space: no emptier place.
Again, the balloon analogy in the Cosmo Basics sticky thread may help visualize.
 
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poeteye said:
If the universe is uniform no matter in what direction you look , then looking in two opposite directions, two observers, if each looks far enough will see the Universe at its earliest time -- The Big Bang. Therefore, the event of the Big Bang cannot be from a point singularity.

Take a look at the diagrams on Ned Wright's website: http://www.astro.ucla.edu/~wright/cosmo_02.htm#DH
 
https://en.wikipedia.org/wiki/Recombination_(cosmology) Was a matter density right after the decoupling low enough to consider the vacuum as the actual vacuum, and not the medium through which the light propagates with the speed lower than ##({\epsilon_0\mu_0})^{-1/2}##? I'm asking this in context of the calculation of the observable universe radius, where the time integral of the inverse of the scale factor is multiplied by the constant speed of light ##c##.
The formal paper is here. The Rutgers University news has published a story about an image being closely examined at their New Brunswick campus. Here is an excerpt: Computer modeling of the gravitational lens by Keeton and Eid showed that the four visible foreground galaxies causing the gravitational bending couldn’t explain the details of the five-image pattern. Only with the addition of a large, invisible mass, in this case, a dark matter halo, could the model match the observations...
Hi, I’m pretty new to cosmology and I’m trying to get my head around the Big Bang and the potential infinite extent of the universe as a whole. There’s lots of misleading info out there but this forum and a few others have helped me and I just wanted to check I have the right idea. The Big Bang was the creation of space and time. At this instant t=0 space was infinite in size but the scale factor was zero. I’m picturing it (hopefully correctly) like an excel spreadsheet with infinite...

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