I read the article about Stephen Hawking’s words in the Mirror. I seriously doubt he would have said “replying to aliens is a bad idea”. If he said it, then he was joking, and the paper has reported it out of context. What do you expect from the Mirror?
As for detecting a signal, I think it may happen soon. I personally think that large numbers of aliens have the technology and motivation to beam focussed signals in the direction of possible habitable planets. Why would they do that? For the same reason that nations spread their discoveries to others. Why did we send the spaceship Voyager 1 on a 40’000 year trek to a star called AC +79 3888? Why do people make Youtube videos? Because intelligent life loves to share. That’s why they are broadcasting to the cosmos.
Our technology of today may not be able to receive the signals. With trillions of places to look we may not be looking in the right places. It is only a question of time.
Thanks for your answer!
I love the way you think about that and I agree for the most part!
I also believe it's only a question of time. We only vary a little on the specific time frame! But who knows? An interesting signal could already been picked up and might just be waiting for the regarding data analysis to be "seen", it could happen today.