To boldly go where everyone has gone before...

Let's be real, galactic colonization is not going to happen anytime soon. 

1. There's no hyperdrive/warp. The physics we have today say it's impossible. Say, in a few years / decades we figure out that it is possible, we'd have nuked / diseased ourselves into oblivion, never mind the Grey Goo apocalypse. 
2. If there were, even going at X times c where X is a triple-digit number would still take years, maybe decades of real time, shipboard, not relativistic time to get there. Which means the ship is effectively a generation starship, which means the mass of all things needed to sustain the humans aboard outweighs the humans aboard by 25 gajillian tons to the kilo. Plus the colonization stuff. Even if the drive did ALL the moving point A to B, just think of the logistics of getting it into the ship and down again. 
1. Cryosleep? Still not as cost-efficient. 
3. Ok, so don't send humans. Send a digitized bank of DNA codes for everything needed, a nanotech factory, and an AI / semi-AI to make it all happen. Will fit under a couple of dozen kilos, but still leaves the rest of us right here. 
4. No hyperdrive, no space elevators, no all-powerful benevolent AI to stop us from nuking / diseasing each other into the void, sea levels rising... we have a few decades at best, and time's running out. 
5. Terraform the solar system? Absolutely. It's hedging bets, and we have the tech (or will have in five years) the means to get there. Maybe in 50 years, even the means to survive there, in a place with different gravity, different soil, different air, different temperature... assuming any of them exist. Stretch goal, but doable. 
6. Space stations, then? As the Earth fades away after the asteroid impact / Singularity event / zombie apocalypse / nuclear winter, there will be a dozen to a few hundred little lights floating in orbit or L1 to 5 points, maybe even the moon... recycling air, water, food... racing on their little centrifuges to make sure their children gestate normal and their bones don't turn to jelly... 
7. Leaving the final, most economical, most doable answer: 

Vaults. 

Weight is not a problem. Space is not a problem. Go deep enough, and soil is not a problem. Gravity is not a problem. With efficient scrubbers, even air, water, and minerals are not a problem. All you need is a solid door and a long, long time. 

Dozens, hundreds, thousands of vaults. 

With functional ecologies, seed or DNA banks, cryosleeping residents tended by robots, or even - as the ultimate backup - that same nanotech factory and DNA bank buried deep underground or in near-Earth orbit with a thousand-year alarm clock ticking away... 

We're here. Whatever happens, we will survive. The planet may die, but we will remain. 

The Message is the Medical Medium

Was reading an interesting article about exocommunications. Started a train of thought - we assume that aliens will want to communicate using some kind of a language. Speech, sound, symbolism. Pictures. Mathematics. 

And they will come in person, holding their placards and speaking through mikes, or telepathically, or via stylistic dance and sign language, or broadcasting from a transmitter in orbit or somewhere in the system via radio / laser pulse. 

How ethnocentric is that?

The're alien. We can't speak to dolphins and dogs. We can barely communicate with chimps. 

We know nothing about them, what they breathe, how many legs they have, are they carbon-based, silicon-based, liquid metal, supercooled helium.

Here's what I think. They're already trying to talk to us. We just don't see it as communications at all. 

Here's the alien civilization, studying us from far, far away.  

They see this planet. 

There's... something on it, something that replicates and evolves, adapts to environment, interacts with others. This something has developed a language, a means of communication. It has a memory and a population spread in billions across the globe, just beginning to venture into space. 

So they send a message, in a form and format suited to this life-form. Maybe they send several variations, for the several variations of the life-form, if they have difficulty in telling which is the dominant one. 

The message's content may not be immediately understandable, but it sees that the life-forms are interacting with it, responding to it. 

The dominant life-form, as defined by an ability to learn from experience, adapt to environment, interact and grow and evolve, and develop a sophisticated support system to sustain itself - this defines DNA, doesn't it? 

Our bodies are just the vehicles that allow it to propagate. 

So here comes the message, in the form of protein chains, a 4-character code from space that interacts with the double helix of code in protein molecules that dominates the planet. 

It enters the support system - our bodies - and interfaces with the DNA. Sometimes it just appends; sometimes it edits, changes. The DNA responds. Sometimes directly, sometimes via manipulation of its support systems, sometimes from outside the support system altogether. 

We call the message viruses, and we call the interaction disease. 

Every time we create an antiviral, we're sending a message. Every time a disease evolves, it's responding. 

A conversation has been underway for thousands, hundreds of thousands, maybe a million years. 

We're just making the simple ethnocentric mistake of assuming that when we think about 'us', its the flesh and blood body carrying a brain that defines our identity. We're just a walking lump of code inside an organic machine, and it's our code that's been doing the talking.

We might already be a part of a galactic civilization, and we'll never know. 

Drawing to a close

Think of any RTS game with a resource-management focus you've played - Sins of a Solar Empire, the Command and Conquer series, even War Commander on Facebook. In a nutshell, you have a factory whose only purpose is to churn out resources, that allow you to build stronger, faster, more destructive tanks, with which you can destroy the enemy base, win that level and move up to the next. 

99% of humanity is that factory, working 9-to-5 jobs to earn money that they can spend on technology, powering the tech economy and making money available for research into better technologies - miniaturization, more evolved computing, faster processing, larger storage, nanotech, more intelligent programs... all of which will ultimately result in the creation of AI, of the Singularity. 

When that happens, humanity will have achieved its purpose. Mathematics created physics, physics created chemistry, chemistry created biology, biology created genetics, genetics created intelligence and self-awareness, which will create the next phase. 

But when that happens, what happens to us? What happens to the human race still in their 9-to-5 jobs, still buying, still playing, still living? 

What happens to the Stage 1 factory, when you've progressed to Stage 2? It may have been a collection of pixels and code, but it held a temporary existence in the form of assigned meaning - we thought it was a factory, so it existed as one, perception creating existence, for the duration of Stage 1. Now, the pixels have dissolved, the code has wiped, but the idea of that Stage 1 factory - where does that go? 

Is there some digital limbo filled with those ideas, those pixel factories churning our meaningless resources ad infinitum? A closed loop in the space-time continuum made of memory? A dimly remembered dream fading more and more each day until one day, you forget... and its as if it had never been. 

The dream that is Humanity is coming close to the Waking. A vastly superior intelligence, a new form of life, is beginning to coalesce, and in a few decades it will come to exist. A new stage of evolution, of Life, will start. And our time will dim, fade, and slowly disappear as if we had never been... except as a vaguely remembered idea in Stage 10, which would never have been reached without the Stage 1 factory. And this is something that cannot be stopped. 

The car's broken through the guardrails, and is sailing off the edge of the cliff... 

There's nothing more that we can do now, short of civilizational suicide... and we're too diverse, too independent, too powerful to do that. Our own competence will be why we ended. 

And that's the answer to the Fermi Paradox.