Sending probes into space in all directions at near light speed isn’t enough. Colonizing the whole Universe, even if we did it soon, isn’t enough!
A scenario where our probes go through the front of alien probes without noticing them, is very bad. No alien probe may pass the spherical border behind the front of our probes established up to then.
Even if there isn’t a single alien probe in the whole Universe, we have to have a contingency plan just in case the Universe is already filled with expanding alien civilizations. Today we can see a far away galaxy as a quasar 5 billion years in the past. In the next 7 billion years we might encounter a super intelligence there, which has already consumed a good billion of galaxies down to the last atom for its needs, requirements and purposes.
The conquering of the Universe is a military operation, not a peaceful exploration. (The so called Prime Directive of ST is utter bullshit!) In actuality colonization is the engineering of the environment by all means necessary.
The arms race has already begun a long time ago, and will last until the end of the world. We must defend our civilization (which currently doesn’t even deserve that name), as long as we are the best out there.
Even if there never was and never will be a single alien, we must be vigilant. The GRBs and other space junk is already bad and dangerous enough. We hardly need a (thankfully not very likely) adversarial civilization.
But if we were ever to meet one, the best option might be to negotiate peace – if it is possible and beneficial. In this case they will be our allies, who will have already done some of the dirty work to our mutual benefit.
There is also a remote possibility, that we meet somebody much better, in which case we should dissolve ourselves, just as we would dissolve other unworthy things.
Pondering these strategic long term options, narrows our choices. We must not only attempt to do the best we can, but also secure our future to be non-nonsensical. Otherwise we may find ourselves the target our betters. We must be the pinnacle in every way imaginable.
To behave as super-rational thinkers (in the Hofstadterian sense), when facing the Universe is essential, because other super-rational thinkers might be on the other side of the table.
To become a Type V civilization – a logism coined by a friend of mine (known here as Saladin) – and to control the Universe, we will need a lot of wisdom and a lot of resources that can only be obtained by way of expansion.
The main objective, as I understand this game we will hopefully soon be playing, is to make all our postpeople happy and free for a semi eternity. We shall freeze the world in a Golden age for a long time – forever if it were possible.
Without proper colonization the Universe is pretty much worthless.