Listen, I know the government broke down and finally admitted that aliens exist, but the news kind of fell flat, considering everything else that’s going on. And I get it – honestly, most of us grew up assuming that was true.

This simulation, though, shows that not only is it true, but they could be slowly growing in numbers throughout the universe.

Now that we’ve found a bunch of planets in the habitable zones around their stars, as well as new classes of exoplanets that could harbor life, it seems as if a discovery of aliens on another planet should be right around the corner.

The Fermi Paradox was an early attempt to answer this question. Here’s a quick video to explain that.

One astrophysicist tried to estimate how long it would take other civilizations to colonize the galaxy – and the answer was, if they really put their minds to it, not that long.

“Assume that we eventually send expeditions to each of the 100 nearest stars. These are all within 20 light years of the Sun. Each of these colonies has the potential of eventually sending out their own expeditions, and their colonies in turn can colonize, and so forth.”

There are a lot of “ifs,” though.

“If there were no pause between trips, the frontier of space exploration would then lie roughly on the surface of a sphere whose radius was increasing at a speed of 0.10c. At that rate, most of our Galaxy would be traversed within 650,000 years. If we assume that the time between voyages is of the same order as the length of a single voyage, then the time needed to span the Galaxy will be roughly doubled. We see that if there were other advanced civilizations in our Galaxy they would have had ample time to reach us, unless they commenced space exploration less than 2 million years ago.”

If these estimates are even close to accurate, we should have encountered aliens by now. The fact that we haven’t, the paper says, means they aren’t out there. In fact, he considers the lack of contact “strong evidence that we are the first civilization in the galaxy.”

According to the team in a new paper, though, expansion might not be quite so uniform. The model they created is composed of cells representing habitable planets. A 3D spherical section of this model was then isolated with a “civilization” at the center. This civilization moves out to the other cells at a constant speed, using resources from the new planet to keep going.

They used three different universe models – a static, a matter-dominated, and a dark matter-dominated. In both matter and dark-matter dominated universes, there are planets that are receding faster than the speed of light, which means there is a limit to how much of the universe we can see.

As the universe expands, the distance between us and all other stars increases and what we can see shrinks.

So, there is a limit, and it shrinks as the universe expands.

Allan L. Alinea, co-author of the paper, says there could still be time.

“However, for a matter-dominated universe, in accordance with Friedmann Equation, the comoving Hubble Sphere is shrinking instead of expanding. Put simply and informally, those planets far away from a reference planet in this Universe (that are initially ‘moving’ faster than the speed of light) are ‘slowing down,’ making them reachable, at least in principle.”

Civilizations in a dark-matter dominated universe will be able to reach fewer and fewer planets as time goes on, but they should still be able to colonize in a reasonable time frame.

In the model the expansion began slowly, then sped up as they spread and had more options from nearby planets. Then it slows as they run out of options. The study suggests aliens may not have colonized the galaxy yet, and are still in the initial “slow” phase of expansion.

So just because they haven’t come by yet, doesn’t mean they won’t.

If you thought that was interesting, you might like to read about the mysterious “pyramids” discovered in Antarctica. What are they?