Question

Why has our estimate of the size of the universe changed in the past few centuries?

Answer 1

The estimate of rate of radial expansion is about 1 light year (ly)/year, So, 1 century ago, the radius from BB center of `our` universe might have been 13.77 ly-100 ly=13.77 ly, after 4-sd rounding.-

Explanation:

The radial expansion since BB event 13.77 billion years ago has now

reached 13.77 billion ly. The rate is nearly 1 ly / year.

So, over a century, the radius increases by 100 ly, nearly.