What power would a transmitting lasers beam need to be in order for us to detect it?
Light coming from a star alone filtered to one part in 10,000 amounts to 4 Joules of energy every nanosecond. Therefore, a laser signal coming from near the star must exceed 4 Joules within a nanosecond in order for it to outshine the star. Modern lasers designed for nuclear fusion can exceed this power requirement by some 300,000 times (see the technical paper). Even if the exact frequency of transmission is unknown, such a laser would still outshine the sender’s star by 30 times during the nanosecond pulse without any filtering. • What is the maximum distance from which we could detect a signal? Establishing contact as far away as 100 light-years should present no problem. Using research grade equipment, detecting signals from distances up to 1000 light-years are feasible. • For what time period is each star examined? Some debate lies within the details of the question of how long each star should be exmined. If we assume that the sending civilization will try to communicate with the
