For many years I had an interest in the ancient astronaut hypothesis. Unfortunately, I have not found the kind of credible discussion that I want to see. I will try to start on that path myself and see where it takes me.
When I first heard of the ancient astronaut hypothesis, over 40 years ago, I was immediately fascinated. At first I was firmly convinced. But as I dug into the “evidence”, it just dissipated in a puff a smoke. Nevertheless, I was still fascinated with the idea, albeit, disappointed there didn’t appear to be any real evidence.
I think it is plausible that aliens visited Earth in the past. I looked for people who have done a serious investigation, but only found vague comments about some speculation by Carl Sagan. That left me unsatisfied.
If there really were ancient astronauts,
what kind of evidence would we find?
I have not seen any evidence that would convince me that the ancient astronaut hypothesis is valid. Old stone monuments can be easily explained by the skills people in the past could draw on. I am also uncomfortable with the implied racism inherent in some of the evidence.
I need to decide what kind of evidence would convince me. This is not a simple question.
Before we can speculate, we need to explore some other questions.
Where are they from and what is the level of their technology?
This could be two questions, but I think they need to be linked. The further away they come from, the higher their level of technology would be need to be. The more advanced their technology is, the harder it would be for us to recognize it. Their level of technology would affect how many of them there were and if they sent robot probes instead of living beings.
Why did they come here?
If they came here for scientific study, the evidence would be much different than if they came for colonization. Would Earth have been their primary goal, or might it be a way point on their route to their final goal.
Were they successful?
This is related to why they came. If they accomplished what they came here for, the evidence would be different than if they had failed. Between full success and abject failure there is a wide range of out comes.
When did they come?
Aliens who visited Earth billions of years ago would be much harder to detect than aliens who visited after human civilization arose. A closely related question would be how long did they stay. Did they ever leave?
How did they interact with humans?
If aliens visited openly, then evidence could be found in the cultural materials of ancient societies. If they visited clandestinely, we would need to look elsewhere. They might have engaged directly with humans or may have simply ignored them.
I suspect that there are many more questions that could be asked. For now though, I will cogitate on these as fodder for future blog posts.