It’s very likely we are not alone.
The Drake equation seeks to estimate the number of civilizations in our galaxy with which communication might be possible. It uses 7 unknowns to get at this number. Those unknowns are written below:
N = R* x fp x ne x fℓ x fi x fc x L
- R* = the average rate of star formation per year in our galaxy
- fp = the fraction of those stars that have planets
- ne = the average number of planets that can potentially support life per star that has planets
- fℓ = the fraction of the above that actually go on to develop life at some point
- fi = the fraction of the above that actually go on to develop intelligent life
- fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
- L = the length of time for which such civilizations release detectable signals into space
Lucky for us, scientists can approximate the first three unknowns with pretty good accuracy. There are questions of astronomy and astrophysics which can be answered, with some degree of certainty, from Planet Earth. The last two factors ask the scientist to ponder things which are highly abstract. These unknowns are fc (the fraction of civilizations that develop a technology that releases detectable signs of their existence into space) and L or Longevity (the length of time for which such civilizations release detectable signals into space).
I know for a lot of people it’s hard to imagine some alien creature listening to a radio. But remember, radio waves are one of many forms of electromagnetic radiation. If these aliens transmit anything in the electromagnetic spectrum, chances are we can detect it. We transmit various electromagnetic waves all of the time. Therefore, it’s not too hard to imagine aliens grasping and utilizing such a broad form of technology.
The most intriguing mystery of the drake equation lies in the L. That L stands for longevity. Longevity in this context refers to how long civilizations release transmissions into space. Longevity is tied to a variety of factors, which are highly relevant to all of us on Earth. If we find alien transmissions, that means that those planets had a longevity large enough for us to detect them. This could give us a clue to our own longevity.
Perhaps we are a species in its twilight age. Maybe most civilizations that acquire sufficient technology end up killing one another. As a result, we do not expect to find many transmissions because by the time any species develops transmission technology, they are on their way to extinction. Of course, this is a highly speculative form of anthropology for everything that’s not Anthropomorphic. But, we should keep in mind that we are not special. According to the Anthropic principle, “we must be prepared to take account of the fact that our location in the universe is necessarily privileged to the extent of being compatible with our existence as observers.” If the reason we have not found any alien transmission is due to the fact that they have all died out (they have a low L), perhaps we should be more wary about our own future. We should not assume that we can succeed where non-earthlings have failed. Of course, we may be a species in our infancy. We have not been detecting signals that long, and our galaxy is a very large place. Don’t despair just yet.