The big bang - theory teaches that there was a temporary singularity out of which energy streamed(The Lambda-CDM model says about 13.8 billion years ago).
But why is this region preferred, and why is it the only region in the infinity of the space - except from the strangeness of that theory of cosmic energy out of a very small point, a formation of matter, space and time from an original singularity. Thus, shortly after the Big Bang, the density of the universe would then have exceeded Planck's density (the energy density would be nearly infinite). Therefore exists no generally accepted theory for the very early universe.
Hmm ... an esoteric explanation would be the creative omnipotence of God, which can also create a nearly infinite density, but I do not want to 'support' the materialists here ....
The cosmic microwave radiation comes after that model from the time about 380,000 years after the Big Bang. But the stream of infrared light, which was produced for a while, should have passed our region, despite from that the energie was radiated into a 3dimensional space, and therefore the amplitude at the outer parts of the universe should be very much weaker than in the center....
The other problem is that only light out of the outer parts of the universe can reach us which has been reflected from some matter.
Other new theories are that the expansion of the universe is connected with the shrinking of a parallel universe. Some modern directions of quantum theory are based on this hypothesis(quantum universes).
Already at the time of Albert Einstein - when the possible size of the universe was not yet known - most physicians began to have doubts about the theory of a stationary universe.
The background of these doubts was the model that the produced light cannot be absorbed continously by the intergalactic gases und the cosmic dust, because after a time the absorption of energie must have lead to a plasmatic state which makes the absorption of further engergy impossible. The universe would then be filled with bright light.
New theories beleive that the expansion of the universe is caused by the expansion of the dimension "space" and not by accelerated matter. But modern measurements show that the expansion of the outer space of the universe is much bigger than it should be after the theory of the " big bang".
All this stands in contradiction to EINSTEIN whose theories are based on a stationary universe.
These modern theories are based on a the "dark matter", out of which most of the universe is proposed to consist, which causes gravitation - lenses in astronomy. But 2018 : New galaxis NGC-1052( Wiki )
(Thinking of the small amount of glowing matter in the universe and of the fact, that the light needs about 50 000 000 000 years to cross the universe, and that the light is send into a threedimensional space(in which it batters), the facts seem to be a bit different. Therefore the low brightness in the universe is not so unusual.)
A different theory is emergence of neutrons in a nearly unlimited part of the infinite space out of which many universes were formed. But the esoteric model of a central sun stands in contradiction to the theory of black holes.
== The redshift of the stars - an error ==
Modern astronomy measures movement-vectors of very old light which arrived at our planet. But the composed vector of the movement of our watching position is not linear.
The movement of the watched objects is not linear because of the overlayed circles of movements within the subsystems.
Therefore astronomy measures very old movement-vectors and compares them with the momentary movement-vector of our earth which is completely different at our time, and therefore it measures false distances of a time-shifted redshift.
After corresponding (today still impossible) calculation of other distances the " dark matter " would perhaps be superfluous.
Perhaps an unproven theory about Gravitation can solve these problems a bit.
But inspite of the fascinating size of the universe it should not be overseen that we live in a world with the characterists of death and perishableness.
The bright sun in the sky radiates a material light, and photos of the gases and stars within the universe hide these characteristics.
Only the spiritual sun brings nearly eternal life, and it must be our goal to concentrate on this sun which is infinite.