[A.J.Armitage]

None of that matters. If we go to Mars, it's not so we can enjoy the great Martian civilization.

Settlement and colonization is what I have in mind.

[TopQuark]

Settlement and colonization is what I have in mind.

That well may be, but that's not what you said:

if there are intelligent aliens, why aren't they here? That is what I tried to answer.

[MHGinTN]

Our spacetime isn't the same as that of the Angels, yet their spacetime is but 'an arm's length away'. When we learn to make contact with their spacetime from our spacetime bubble that protects us, we will likely have access to the vastness now unreachable in the flesh. I don't think real colonization will occur until that where/when ... I don't think our concept of distance and temporal limits will be the hindrance they are now, when we discover how to access the spacetime realm in which Angels dwell.