Will we find aliens first or will they find us?

[longship]

25. Given the fact that we are in our technological childhood...

I would go with "they will discover us first".

After all, all one needs to do is see Earth's oxygen rich atmosphere to know that there is life here. And that has been true for hundreds of millions of years, radio emissions only about 100 years. Sorry galaxy, no Shadow radio broadcasts for you. Not for a long while.

So just as we are only now building telescopes that can detect the compositions of the atmospheres of extra terrestrial planets that we have only first discovered less than two decades ago, there may be other life within our galaxy that may be observing us. But they are not likely to be listening to our radio broadcasts -- which barely get beyond 100 light years. But our atmosphere alone would flag our planet as one of interest, and that would have been detectable for hundreds of millions of years, and one can substitute light years there, too.