Let’s take a moment to look at our place in the universe.

Now, we’re nowhere near what would be called the center of the universe, but since time and space are relative, we’ll just go ahead and place ourselves at the center of space - after all, from our perspective, we are. This makes things a bit more convenient. As to time, we’re about 13.75Bn years along that axis - for now, we’ll make that relative to the universe. So, if we graph our position in spacetime, we can roughly get this:

Since we can’t see into the future, effectively our perception stops at our current position on the time axis - we can’t see anything past 13.75Bn years on the time axis. The thing is, that’s not our true constraint - the speed of light is our true constraint. Now, the name “Speed of Light” is a tad misleading - What we call the Speed of Light isn’t the speed at which light moves, it’s the maximum speed at which anything in the universe moves. It is the absolute speed limit of our universe: Light happens to move at the top speed available in the universe, which is why we call it the speed of light, but there’s nothing else that moves faster - we can’t get information from one place to another faster than C, which happens to be about 300,000,000 m/s.

This effectively puts blinders on our ability to see the universe - because we can’t transfer information instantaneously, we can’t observe our universe synchronously - everything we see is delayed by the speed limit. Our perceptual universe, then, looks like this:

Anything in the universe that occurs outside that triangle doesn’t exist to us: That is our island in the universe. Our consciousness grows at 300,000,000 m/s, or about 10 trillion Km per year - a pretty good clip, by most measures, but by the scale of the universe, not much. What’s more, the further out we see, the older we see the universe. If we’re gazing at a system that’s five thousand light years away, we’re seeing it as it was five thousand years ago - we have no ability to percieve what’s happened in the five thousand years following, and no ability to see that system as it exists now: for all intents, the 5000 years since we saw that galaxy haven’t happened.

Note that this goes both ways - as far as that galaxy is concerned, the last 5000 years of our history haven’t happened either. For looking at star systems, this isn’t too bad - galaxies operate on a very long time scale. Think of the human race, though, 5000 years ago: we had agriculture and had finished domesticating the animals. Were we to train our instruments on ourselves 5000 years ago, we would have seen nothing. In fact, the earliest reasonably powerful radio transmissions occurred maybe a hundred years ago - let’s turn our ‘perception triangle’ upside down for a minute:

For another species to be aware of us, they need to be within this triangle. For us to hear back from them takes twice as long as for them to hear from us, so they’ve got half the triangle. In short, for a species to know we exist, they must be within 100 light years, and for us to hear back now, they’d need to be within 50. An intelligent species which exists outside that triangle is invisible to us, and us to them - it could take thousands of years before our perceptions overlapped, and the longer it takes, the less ability we have to engage in a two-way dialog.

Beyond a certain distance, effective communication becomes impossible: sentient timescales simply don’t allow it. A hypothetical species which happened upon our first transmissions today would be responding to a species for whom powered flight was still a dream. Think of the last hundred years of human development and project forward another hundred - and remember this is the best possible scenario and the absolute tip of our perceptual island! In what capacity could we maintain a dialogue over these timescales? To whom would a species be speaking in a thousand years?

The size of this triangle will grow as we move forward, as will our perceptual island in space, but for all the wonders and size of the universe, we’re stuck between two constraints: The infathomable size of the universe and our inability to percieve it.

My appologies for what’s turned into a very depressing post. I’m a child of Sci-Fi: I believe in mankind’s future among the stars, and I can hope for a way to violate what seem to be the iron-clad rules of the universe, but, at least for today, humanity are the only inhabitants of our island: alone in our own universe, waiting for something else to wash up on our shores.

(For a moderately less depressing view of man in the universe, I suggest David Deutsch’s brilliant TED talk)