I think the great filter is the square-cube law, and the relatively short period of time when you need megawatts, across a wide swath of the EM spectrum, to affect communication with any usable bandwidth.
It may be that all the older civilizations are no longer throwing their signals out, omnidirectionally, with such power that they're still somewhat recognizable from Earth.
Even a colony or daughter colony, assuming you don't have a technological slip, would presumably use only the mature communications systems, that relied upon highly directional antennas, highly tunable transmitters, and highly discriminating receivers. This assumes that future science doesn't offer something that is as advanced over radio as radio is over shouting, drums and horns, signal fires, and semaphore towers.
So, you may only get a tiny window, of maybe a hundred years or so, to see the use of radio by a distant civilization, then they go almost dead quiet. Not because they're not talking, but because their technology has improved.
As for Dyson spheres. Yes, a colony may simply have to be written off as anything but a future descendant of the origin civilization, but I think that would still happen, if rarely. What may happen, instead, is a civilization which can't save its sun, instead harvesting everything it can and heading off to a single, new, star system to start over. A massive upload period, followed by a multiply-redundant fleet of data ships and Neumann probes, headed off to one new home. There could be a thousand year gap in the history of such peoples, as their ships bridge the space between their old home, with is soon to go supernova star, and their new home, just far enough to be safe from the effects of the supernova.
Or maybe not. Aim for that nearby carbon world in its system's Goldilocks zone. When you get there, the planet, which is almost perfect now, if alien, will have been recently sterilized and be ready for re-seeding with something very like the original home planet's ecosystem.
It may be that all the older civilizations are no longer throwing their signals out, omnidirectionally, with such power that they're still somewhat recognizable from Earth.
Even a colony or daughter colony, assuming you don't have a technological slip, would presumably use only the mature communications systems, that relied upon highly directional antennas, highly tunable transmitters, and highly discriminating receivers. This assumes that future science doesn't offer something that is as advanced over radio as radio is over shouting, drums and horns, signal fires, and semaphore towers.
So, you may only get a tiny window, of maybe a hundred years or so, to see the use of radio by a distant civilization, then they go almost dead quiet. Not because they're not talking, but because their technology has improved.
As for Dyson spheres. Yes, a colony may simply have to be written off as anything but a future descendant of the origin civilization, but I think that would still happen, if rarely. What may happen, instead, is a civilization which can't save its sun, instead harvesting everything it can and heading off to a single, new, star system to start over. A massive upload period, followed by a multiply-redundant fleet of data ships and Neumann probes, headed off to one new home. There could be a thousand year gap in the history of such peoples, as their ships bridge the space between their old home, with is soon to go supernova star, and their new home, just far enough to be safe from the effects of the supernova.
Or maybe not. Aim for that nearby carbon world in its system's Goldilocks zone. When you get there, the planet, which is almost perfect now, if alien, will have been recently sterilized and be ready for re-seeding with something very like the original home planet's ecosystem.