Answer:2000 light year
Explanation:
Advanced civilization is 1000 light-years away
1 light-year is the distance traveled by light in 1 earth year i.e. 365 days with the speed of light i.e. [tex]3\times 10^8\ m/s[/tex]
If civilization is 1000 light-years away then it would take 1000 year to reach there and another 1000 year to come back to earth (If all other factors remain constant)
So totally it would take 2000 light-year to hear out the radio wave.
