How do we calculate how big the universe is?
In: Physics
We can’t do that, there is an estimation of the minimum size but the size might be infinite.
We only know of large the [Observable_universe](https://en.wikipedia.org/wiki/Observable_universe) is and it is done by knowing how old the universe is and how it expands in size and you get a result of the current size of radius of 46.5 billion light-years. This is the part of the universe that is possible to observe from the earth.
The size is the current size. What is today 46.5 billion light-years away was a lot closed when it emitted the light that reaches us now. The light from it only has traveled the age of the universe to us. So the light for the object 46.5 billion light-years away only has traveled 13.7 billion light-years.
From the measurement of the flatness of the universe, you can come to the conclusion that it is at least 250 times the size of the observable universe. So it might be finite but it might also be infinite in size.
So we do not know the size of the universe it is an open field of research where we have not reached a conclusion. It might be the case that it is impossible to know the size.
So the best estimation is 250 times the observable universe to infinite size.
https://en.wikipedia.org/wiki/Universe#Size_and_regions
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