From Wikipedia, the age of the universe is 13.8 billion years. Earth is 4.5 billion years old. The first simple cells appeared 3.6 billion years before present (ybp). Dinosaurs appeared 0.3 billion ybp and died 0.065 billion ybp, lasting a span of 0.235 billion years. Anatomically modern humans have been around for 0.0002 billion years. The Bronze Age and early human civilization began roughly 0.0000055 billion ybp (3500 BC, or 5500 years ago).
The point is that humans have been around for a very short time on the scale of the universe. In this brief window we have developed some impressive technologies. The pace of progress in the last 200 years has been spectacular. What lies ahead in the next 200 years is anyone’s guess, including whether humanity will even still be around. How long do you think humans or their descendants will continue to exist? Will we be able to make the great technological leap to allow us to sustain a significant legacy on earth or beyond? Knowing our destructive capacity, depletion of resources, and human nature, getting anywhere close to the dinosaurs’ length of rein right now does not seem likely.
While our understanding of the universe is far from complete, I get the sense that we have a pretty good idea of its physical limits. So far, in all the forms of information gathering we have deployed, we have not been able to detect any signs of alien presence.
I assume that one goal of an advanced species is interplanetary colonization. Reasons for expanding across galaxies include harvesting resources, supporting a larger population, exploration, research, and reducing the risk of species extinction. If this assumption is true, then how far would an advanced species expand across the universe? There is no reason to limit this expansion – they would keep going up to or beyond the edge of the universe if they can. In order for such a feat to be possible, the method of travel or surveyance must be extremely fast. It would probably have to be faster than light to traverse the immense distances.
If an advanced species reached a sufficient level of technology, and if it was possible at all, then they must have already charted and/or colonized the entire universe. And since none has done it yet, none will do so in our future.
To illustrate my thesis, the hypothetical universal timeline can be split into three phases: pre-universal conquest, the period of exploration, and post-universal conquest. We are not in the last phase, because if we were, we would know about it. The chances of us being in the second phase depend on how long we’ll be around.
Take the following example. The aliens are a farmer pushing a rake through soil. The raked soil is explored territory, while unraked soil is unexplored. The field is huge and will take some time to rake entirely. Humans appear when a snowflake touches the field on a hot summer day. Once the snowflake hits the ground, it melts in a few seconds. If we fell on a raked area, we’d see the signs of previous visitation by the rake marks. The chance of us being in the exploration phase is like the rake passing over the snowflake immediately after we hit the ground before we melt into the soil. The longer we can prolong humanity’s existence, the longer the snowflake can last before it melts, but so far, the time of our existence has been negligible.
That leaves us in the first pre-conquest stage, which must be the only possibility. We won’t be able to meet the aliens in the time we exist.
There are some other points I’d like to address. There is the possibility that advanced aliens exist, have charted the universe, know that we exist, and deliberately stay out of our awareness. This is like the Prime Directive from Star Trek. They will not interfere with our affairs until we reach a suitable stage of political/technological development. We are the animals in the zoo. Alternatively, advanced aliens are out there, but communicate in a medium that we have been unable to detect or decipher. These are valid arguments that I cannot completely dismiss.
I cannot claim that I know too much about cosmology myself, but it seems collectively we know an impressive amount. I mean, we can estimate roughly the age of the universe, its size, shape, speed of expansion, its boundaries, its origin, the forces at play, the celestial bodies, astronomical phenomena, laws of nature, and so many other things. All this, all from a tiny little speck, in a tiny little time frame. We could very well be totally wrong about all of this and the truth is completely different... but do you really think so? Do you really think we are that far off from everything?
All I can say is that given our current understanding of astronomy, cosmology, and physics, radically new universal properties are difficult to accept. I have some level of confidence that we are at a sufficient level of understanding of the universe to rule out certain possibilities. Of course, we’ve made major mistakes before, for example, on the theories of flat earth, heliocentrism, or even manned flight. But that was before a more rigorous application of the scientific method. I’d like to believe that our current conception of the universe, and the scientists that tell us so, are a bit closer to reality.
What if the advanced aliens have charted most of the universe but for some reason deemed it unnecessary or not worth their while to come to our corner? Perhaps it was a particularly dangerous zone and not accessible. We remain in the unknown darkness. As long as they do not come in looking for us and we do not venture out of the corner, contact will not be made. And the very reasons they cannot come in makes it all the more difficult for us to come out.
There is also the point that an advanced species may have no interest in colonizing or expanding across the universe. Perhaps physical bodies will no longer be relevant if we can morph into a nebulous network of consciousness. Nevertheless, traces of such forces must be detectable. If their own sphere of influence is limited, then the chances of communicating with them remains closed off.
What if humans themselves will be the ones to achieve universal conquest some time in the future? Again, the chances of that is extremely small. Consider the potential number of intelligent life forms likely to have ever existed. It should be astronomical. It is highly unlikely that we alone, out of all of them, will have the right intelligence and resources to expand across the universe first.
That gets me to my final point. While life in the universe may be abundant, I think humans are special. On Earth alone, in the entire time that life has ever existed, humans occupy a tiny fraction. Yet none of the previous life forms had any impact on Earth as the same way we have. It’s one thing for an extraterrestrial cell, amoeba, jellyfish, fish, tree, flower, snake, insect, lizard, bird, dog, camel, deer, dolphin, or lion to be skittering about. It’s quite another to see a human building houses, making clothes, driving cars, sending light speed communications across the planet, fly in airplanes, and flush waste down toilets. It could all have been the result of opposable thumbs, or cooked food allowing us to divert energy away from digestion to grow bigger brains.
Intelligent alien life is probably out there, but what humans have been able to achieve is remarkable. I believe the amount and extent of alien advancement surpassing our own could be lower than one might otherwise expect from the numbers.
This was supposed to be a pre-amble to another subject I wanted to write, but it turned out I had more to say on this than I expected.