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Maybe the questions is too stupid to be asked or I do not know the technical words, but I could not find any answer to this question.

Here is how I started to think the title: First I thought of if we look far enough if we could see Big Bang theoretically. The answer was "No", due to reasons such as opaqueness of the early Big Bang and expansion. This is okay. However, then there was a second question arised: Even if we could, which direction to look at? Then I thought if it is the furthest and the oldest, it should not matter. Because any direction we looked at furthest and oldest we should see the Big Bang if we could.

Then, I know I made too many assumption, but does this conclude that we are surrounded by Big Bang and the universe is expanding not outwards but inwards?

As I said maybe question was way too stupid, but still I want to hear some ideas/facts.

Thank you.

By the way this is the first time I post a question, I have no experience, so sorry about any mistakes I made.

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    $\begingroup$ It would help if you remembered that what we see far away from us (the old stars formed early in the universe) does not reflect what is actually at that location, due to the finiteness of the speed of light. To be concise, if we could see the big bang, then it would not mean it happens "right now", but that it happened a while ago. $\endgroup$ Aug 19, 2023 at 10:51

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Are we surrounded by (the) Big Bang ?

Yes, we are. The microwave radiation that we observe in the cosmic microwave background consists of photons that were emitted when the universe was less than four hundred thousand years old. These photons arrive from all directions, confirming your conclusion that we could potentially see the Big Bang in any direction. The reason that we cannot actually see photons emitted soon after the Big Bang is that up to four hundred thousand years after the Bing Bang the universe was so hot that almost all matter was ionised, and the universe was opaque to electromagnetic radiation (in the same way as you cannot see through the Sun, for example).

In theory, we could "see" an older relic of the Big Bang if we could detect the neutrinos in the cosmic neutrino background, which were emitted very shortly after the Big Bang (since neutrinos have no charge, they were not affected by the ionised matter in the early universe). Our current neutrino detectors cannot detect such low energy neutrinos or separate them from other sources of neutrinos, so at the moment we cannot directly detect the cosmic neutrino background. But, if we could, we believe it too would come from all directions.

Does this [mean] that ... the universe is expanding not outwards but inwards ?

No. The universe is neither expanding outwards nor is it expanding inwards. Space itself is simply expanding i.e. the proper distance between us and distant galaxies is increasing with time, and the further away (and so the further back in time) we look, the greater the rate at which the proper distance is increasing - this is known as Hubble's law.

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  • $\begingroup$ Conceptually, I think the facts described in this answer are easiest to grasp through Guth's observation (in his pop-sci book titled "The Inflationary Universe") that, if what we perceive as the Big Bang had not happened "everywhere at once", the area in the direction of it would remain consistently brighter, day and night. $\endgroup$
    – Edouard
    Aug 21, 2023 at 13:22

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