I get that light takes time to travel and that we can look at far out stars and galaxies and understand that they’re thousands or millions of light years away.
But we can only perceive light that’s been coming towards us. How can we see the beginning of the universe if we were in the universe? It’s not like we moved faster than light and billions of years later we looked back to see the events happen.
Wouldn’t that old light have gotten to our spacial position way sooner than we physically got here?
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We cant see the beginning of the universe, earlier light that can be observed is the Cosmic microwave background radiation (CMBR) that was emitted when the universe was approximately 379,000 years old. There is not older light because before that the universe was so warm that the matter was ionized atoms ie plasma that is opaque to light. It is when the universe cooled down so atoms stop being ionized, and start being a gas, the universe becomes transparent.
The big bang is not an explosion in space it is an expansion of space itself. So the universe gets large between us and a galaxy far away without there being any motion at all. Space in between two points can expand faster than the speed of light because it is not motion.
It is motion in the universe that is to the best of our knowledge limited to the speed of light. The exemption of the universe is not motion id is just the distance between points that get larger and that rate can be faster than the speed of light.
The expansion was extremely fast in a fraction of a second after the big bang it is called https://en.wikipedia.org/wiki/Inflation_(cosmology) it explains then slowed down until dark energy resulted in it started to speed up again when the universe was 7.7 billion years old
The emission of the CMBR we observe right now was a lot closer than the 13.8 billion light years it has traveled to reach us. You can calculate the distance from the redshift. It is agreed that the redshift z=1100 for the CMBR the result is that light was emitted 41 million lightyears from us. You can use https://astro.ucla.edu/~wright/CosmoCalc.html and set z=1100 and the distance when it was emitted is D_A . The rest of the travel distance is because the space in between has expanded
This also means that all of the universes are the point where the big band happened. So we can see the CMBR and gold galaxies in any direction we look.
We did not get here because of the motion after the big bang our position relative to far away galaxies is primary because of the expansion of the universe. We could see something quite similar even if we never moved at all. I am not saying we are stationary, the concept does not even make sense because there is no absolute frame of reference all movement is relative to something else.
The best alternative to an absolute frame of reference is the CMBR and we move relative to it at 396km/s. That is more exactly outs sun’s movement because we orbit the sun at 30km/s our motion relative to the CMBR channels during the year but will not average the same as the sun.
So even if we were stationary relative to the CMBR we would see object fat away the same way, the difference is just there is a small difference in redshift depending on the direction we move at .
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