Interstate idea. The title overstated too late though. Following the premise that an expanding civilization is expanding near the speed of light and it's radio

Interstate idea. The title overstated too late though. Following the premise that an expanding civilization is expanding near the speed of light and it's radio will reach us first. We can expect hundreds of years between radio and anything physical. 1) We started producing a lot of radio around 100 years ago. And we are still a long way from expanding at near speed of light. Even with expodential growth in capacity. 2) expanding near speed of light is much less than speed of light. Say 99% of the speed of light. And expanding civilization is probably going to be coming from far far away, just because there is a lot more far far away than pretty close. So say they are comiy from 10,000 light-years away (still close by galactic standards, and incredibly Close by Universal standards). Then the radio they start transmitting when their grown begins has gained on their expansion ba lead of 100years by the time it reaches us Sure on the million and billion year time-scales mostly talking about that 100+ years is very little but it is still generations.