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Considering the following information, why is there a 500,000,000 light year difference? Is the 13.7-billion light year boundary actually based on when the CMBR first emerged from the opacity following the Big Bang?

The observable universe boundary has been placed at 13.7-billion light years. But the most distant object observed so far lies at only 13.2-billion light years

Answer 1

The difference might be due to precision ( 3-sd, 4-sd, 5-sd, ...) in approximations and the precision limits in observation and measurements, in grand units, like , K light years, mega parsec...

Every observatory has its limitations when it comes to precision.

A recent observatory has the potential to reach 5-sd in billion-year units.

Another might end at 3-sd. We must depend on the most important

numbers (m s d) that add up to 13.8.

No estimate, such as 4.246 125 305 6187 light years, exists for

conversion from 4.246 light years to smaller units like AU

distance to Proxima Centauri, the closest star.

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Answer 2

Luke Allen

The boundary of 13.7 billion light-years is based on the age of the current observable universe, not on the formation of the Cosmic Microwave Background Radiation (CMBR). One possible explanation for this apparent discrepancy is that the observable universe grew larger during the period that the CMBR took to become transparent.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.