"Where are all the alien civilizations?"<br>I believe we will detect one in our lifetime. But not make contact with it.<br><br>Under our current modes of observation and communication, everything we detect out there happened years ago. Sometimes centuries/millennia ago or much more. Those aliens are probably not even there anymore.<br><br>And for us to send their progeny a signal, would take just as long. So making contact with any alien civilization we detect, will have to wait for modes of observation and communication we don’t have yet.<br><br>Quantum entanglement perhaps?