For those of us who don’t have time to listen to the podcasts, can you give a quick summary of which particular pieces of evidence are strong? I’ve mostly been ignoring the UFO situation due to low priors. Relatedly, when you say the evidence is strong, do you mean that the posterior probability is high? Or just that the evidence causes you to update towards there being aliens? Ie, is the evidence sufficient to outweigh the low priors/complexity penalties that the alien hypothesis seems to have?
FWIW, my current view is something like:
I’ve seen plenty of videos of UFOs that seemed weird at first that turned out to have a totally normal explanation. So I treat “video looks weird” as somewhat weak Bayesian evidence.
As for complexity penalties: If there were aliens, it would have to be explained why they mostly-but-not-always hide themselves. I don’t think it would be incompetence, if they’re the type of civilization that can travel stellar distances.
It would also have to be explained why we haven’t seen evidence of their (presumably pretty advanced) civilization
And it would have to be explained why there hasn’t been any real knock-down evidence, eg HD close-up footage of an obviously alien ship (unless this is the type of evidence you’re referring to?). A bunch of inconclusive, non-repeatable, low-quality data seems to be much more likely in the world where UFOs are not aliens. Essentially there’s a selection effect where any sufficiently weird video will be taken as an example of a UFO. It’s easier for a low-quality video to be weird, because the natural explanations are masked by the low quality. So the set of weird videos will include more low-quality data sources than the overall ratio of existing high/low quality sources would indicate. Whereas, if the weird stuff really did exist, you’d think the incidence of weird videos would match the distribution of high/low quality sources (which I don’t think it does? as video tech has improved, have we seen corresponding improvements in average quality of UFO videos?).
The US military claims that on multiple occasions they have observed ships do things well beyond our capacities. There are cases where a drone is seen by multiple people and recorded by multiple systems flying in ways well beyond our current technology to the point where it is more likely the drones are aliens than something built by SpaceX or the Chinese. The aliens are not hiding, they are making it extremely obvious that they are here, it is just that we are mostly ignoring the evidence. The aliens seem to have a preference for hanging around militaries and militaries have a habit of classifying everything of interest. I don’t understand why the aliens don’t reshape the universe building things like Dyson spheres, but perhaps the aliens are like human environmentalists who like to keep everything in its natural state. Hanson’s theory is that life is extremely rare in the universe but panspermia might be true. Consequently, even though our galaxy might be the only galaxy in 1 billion light years to have any life, our galaxy might have two advanced civilizations, and it would make sense that if the other civ is more than a million years in advance of us they would send ships to watch us. Panspermia makes the Bayesian prior of aliens visiting us, even given that the universe can’t have too much advanced life or we would see evidence of it, not all that low, perhaps 1⁄1,000. I don’t know why they don’t use language to communicate with us, but it might be like humans sending deep sea probes to watch squids. I think the purpose of the UFOs might be for the aliens to be showing us that they are not a threat. If, say, we encounter the alien’s home planet in ten thousands years and are technologically equal to the aliens because both of us have solved science, the aliens can say, “obviously we could have wiped you out when you were primitive, so the fact that we didn’t is evidence we probably don’t now mean you harm.”
Yes good point. They might be doing this to set up a situation where they tell us to not build Dyson spheres. If we accept that aliens are visiting us and observe that the universe is otherwise in a natural state we might infer that the aliens don’t want us to disturb this state outside of our solar system.
Why would they want the state of the universe to be unnatural on Earth but natural outside the solar system?
edit: I think aliens that wanted to prevent us from colonizing the universe would either destroy us, or (if they cared about us) help us, or (if they had a specific weird kind of moral scruples) openly ask/force us not to colonize, or (if they had a specific weird kind of moral scruples and cared about being undetected or not disturbing the experiment) undetectably guide us away from colonization. Sending a very restricted ambiguous signal seems to require a further unlikely motivation.
Panspermia makes the Bayesian prior of aliens visiting us, even given that the universe can’t have too much advanced life or we would see evidence of it, not all that low, perhaps 1⁄1,000.
Is this estimate written down in more detail anywhere, do you know? Accidental panspermia always seemed really unlikely to me: if you figure the frequency of rock transfer between two bodies goes with the inverse square of the distance between them, then given what we know of rock transfer between Earth and Mars you shouldn’t expect much interstellar transfer at all, even a billion years ago when everything was closer together. But I have not thought about it in depth.
I am unaware if Hanson has written about this. Panspermia could happen by the first replicators happening in space perhaps on comets and then spreading to planets. As Hanson has pointed out, if life is extremely rare it is strange that life would originate on earth when there are almost certainly super-earths on which you would think life would be much more likely to develop. A solution to this paradox is that life did develop on such an Eden and then spread to earth billions of years ago from a star system that is now far away. Our sun might have been very close to the other star system when life spread, or indeed in the same system at the time.
“but perhaps the aliens are like human environmentalists who like to keep everything in its natural state.”
This is the kind of argument that makes me most believe there are no aliens. Like humans, there may be good environmentalists that work to keep worlds and cultures as untouched as possible. But that also represents a very small portion of human impact. No portion of our planet is untouched by humans, including those explicitly set to avoid. And every environmentally-conscious nature park or otherwise is teeming with those who visit and act on it whether inside or outside of set boundaries. Unless this presumed alien culture is so effectively and unreasonably authoritarian that none but the most exclusive are permitted and capable of visitation, I can’t imagine there being aliens here and it not being obvious due not to military sightings and poor camera captures but from almost everyone witnessing it with their own eyes on a frequent basis.
You have anticipated Robin Hanson’s argument. He believes that the only way that the aliens would be able to avoid having some splinter group changing the universe in obvious ways would be if they had a very stable and authoritarian leadership.
For those of us who don’t have time to listen to the podcasts, can you give a quick summary of which particular pieces of evidence are strong? I’ve mostly been ignoring the UFO situation due to low priors. Relatedly, when you say the evidence is strong, do you mean that the posterior probability is high? Or just that the evidence causes you to update towards there being aliens? Ie, is the evidence sufficient to outweigh the low priors/complexity penalties that the alien hypothesis seems to have?
FWIW, my current view is something like:
I’ve seen plenty of videos of UFOs that seemed weird at first that turned out to have a totally normal explanation. So I treat “video looks weird” as somewhat weak Bayesian evidence.
As for complexity penalties: If there were aliens, it would have to be explained why they mostly-but-not-always hide themselves. I don’t think it would be incompetence, if they’re the type of civilization that can travel stellar distances.
It would also have to be explained why we haven’t seen evidence of their (presumably pretty advanced) civilization
And it would have to be explained why there hasn’t been any real knock-down evidence, eg HD close-up footage of an obviously alien ship (unless this is the type of evidence you’re referring to?). A bunch of inconclusive, non-repeatable, low-quality data seems to be much more likely in the world where UFOs are not aliens. Essentially there’s a selection effect where any sufficiently weird video will be taken as an example of a UFO. It’s easier for a low-quality video to be weird, because the natural explanations are masked by the low quality. So the set of weird videos will include more low-quality data sources than the overall ratio of existing high/low quality sources would indicate. Whereas, if the weird stuff really did exist, you’d think the incidence of weird videos would match the distribution of high/low quality sources (which I don’t think it does? as video tech has improved, have we seen corresponding improvements in average quality of UFO videos?).
The US military claims that on multiple occasions they have observed ships do things well beyond our capacities. There are cases where a drone is seen by multiple people and recorded by multiple systems flying in ways well beyond our current technology to the point where it is more likely the drones are aliens than something built by SpaceX or the Chinese. The aliens are not hiding, they are making it extremely obvious that they are here, it is just that we are mostly ignoring the evidence. The aliens seem to have a preference for hanging around militaries and militaries have a habit of classifying everything of interest. I don’t understand why the aliens don’t reshape the universe building things like Dyson spheres, but perhaps the aliens are like human environmentalists who like to keep everything in its natural state. Hanson’s theory is that life is extremely rare in the universe but panspermia might be true. Consequently, even though our galaxy might be the only galaxy in 1 billion light years to have any life, our galaxy might have two advanced civilizations, and it would make sense that if the other civ is more than a million years in advance of us they would send ships to watch us. Panspermia makes the Bayesian prior of aliens visiting us, even given that the universe can’t have too much advanced life or we would see evidence of it, not all that low, perhaps 1⁄1,000. I don’t know why they don’t use language to communicate with us, but it might be like humans sending deep sea probes to watch squids. I think the purpose of the UFOs might be for the aliens to be showing us that they are not a threat. If, say, we encounter the alien’s home planet in ten thousands years and are technologically equal to the aliens because both of us have solved science, the aliens can say, “obviously we could have wiped you out when you were primitive, so the fact that we didn’t is evidence we probably don’t now mean you harm.”
I listened to your podcasts as I generally do (they are great ;-) ),
Correct me if I am wrong, but neither Greg Cochran nor Robin Hanson gave you anything like “there is a >1% probability UFOs are aliens”.
Thanks. Hanson, as best I recall, gave the 1/1000 Bayesian prior of aliens visiting us.
Despite my other comment I’m eager to and definitely will check our your podcast.
Surely if they were showing themselves to the military then that would put us in an unnatural state.
Yes good point. They might be doing this to set up a situation where they tell us to not build Dyson spheres. If we accept that aliens are visiting us and observe that the universe is otherwise in a natural state we might infer that the aliens don’t want us to disturb this state outside of our solar system.
Why would they want the state of the universe to be unnatural on Earth but natural outside the solar system?
edit: I think aliens that wanted to prevent us from colonizing the universe would either destroy us, or (if they cared about us) help us, or (if they had a specific weird kind of moral scruples) openly ask/force us not to colonize, or (if they had a specific weird kind of moral scruples and cared about being undetected or not disturbing the experiment) undetectably guide us away from colonization. Sending a very restricted ambiguous signal seems to require a further unlikely motivation.
Is this estimate written down in more detail anywhere, do you know? Accidental panspermia always seemed really unlikely to me: if you figure the frequency of rock transfer between two bodies goes with the inverse square of the distance between them, then given what we know of rock transfer between Earth and Mars you shouldn’t expect much interstellar transfer at all, even a billion years ago when everything was closer together. But I have not thought about it in depth.
I am unaware if Hanson has written about this. Panspermia could happen by the first replicators happening in space perhaps on comets and then spreading to planets. As Hanson has pointed out, if life is extremely rare it is strange that life would originate on earth when there are almost certainly super-earths on which you would think life would be much more likely to develop. A solution to this paradox is that life did develop on such an Eden and then spread to earth billions of years ago from a star system that is now far away. Our sun might have been very close to the other star system when life spread, or indeed in the same system at the time.
“but perhaps the aliens are like human environmentalists who like to keep everything in its natural state.”
This is the kind of argument that makes me most believe there are no aliens. Like humans, there may be good environmentalists that work to keep worlds and cultures as untouched as possible. But that also represents a very small portion of human impact. No portion of our planet is untouched by humans, including those explicitly set to avoid. And every environmentally-conscious nature park or otherwise is teeming with those who visit and act on it whether inside or outside of set boundaries. Unless this presumed alien culture is so effectively and unreasonably authoritarian that none but the most exclusive are permitted and capable of visitation, I can’t imagine there being aliens here and it not being obvious due not to military sightings and poor camera captures but from almost everyone witnessing it with their own eyes on a frequent basis.
You have anticipated Robin Hanson’s argument. He believes that the only way that the aliens would be able to avoid having some splinter group changing the universe in obvious ways would be if they had a very stable and authoritarian leadership.