Alien visitation

[Moontanman]

If UFO reports are at least sometimes real nuts and bolts space craft from another civilization where do they come from?

 

it would be easy to just say they are all hoaxes or misinterpretations of common objects but in many cases there is embarrassment of data by people that could under different circumstances condemn you to life in prison if not death by their testimony.

 

So if we give credence to at least some reports where do they come from? And how could we detect them by scientific means that would indicate their reality?

Edited May 9, 2010 by Cap'n Refsmmat
reverted

[mooeypoo]

I voted #8 - "Some other option" for a very clear reason: UFOs are "Unidentified Flying Objects". They're unidentified. We don't know what they are. Assuming what they are turns to be false more than it does to be right (there are many examples of stuff like that).

 

The brain plays tricks on us, it's a known fact. Paraedolia happens more than we would like to admit, and it happens to everyone. Our brain has a tendency to see patterns even when none exist.

 

UFOs are unidentified until they are identified. That doesn't mean alien don't exist, and it doesn't mean aliens don't visit the Earth. It means that UFOs are unidentified, and to group all of those together to state that we know what they are is an unbased statement.

 

There are other reasons imho why aliens are not visiting us using crude saucer-like vehicles and kidnap random farmers to poke through their rear (and front) orifices, but that isn't about UFOs.

 

~moo

[pink_trike]

I have no idea. And as much as I still find it unsettling, several decades ago I observed something that was clearly not a natural event or human made. What I observed in the night sky far out over the Pacific ocean with two remarkably intelligent people not given to whims of imagination, was able to cover great distances at speeds that cannot be duplicated by anything that humans have created, and it was able to execute sharp angles and abrupt stops at these high speeds that would be impossible for a human made craft.

 

Before this observation I had assumed that all UFOs could be identified as something human made or a natural occurrence, and I dismissed ideas of alien visitation as, er...wacko. Since that night, I've been forced to consider other possibilities. It became a bit of an obsession for a number of years, but nothing in all of my research even vaguely explains what we saw.

[mooeypoo]

I have no idea. And as much as I still find it unsettling, several decades ago I observed something that was clearly not a natural event or human made.

See, this is my problem with most UFO sightings -- how do you know? You say it's clearly not man-made nor natural... why? How do you know it wasn't something that was man-made in a quirky invironment that made it seem really weird?

 

A few cases of hovering lights were discovered to be perfectly natural phenomena; in certain humidity conditions, the light from passing cars' double lights actually 'bent' over a hill in weird angles, making it seem like hovering lights. I saw the video, it's VERY VERY convincing. Looks completely like some advanced craft.

 

But (a) it was found to be natural, once someone actually looked into it, (b) it was replicated a week later with similar conditions and © even if it was 'advanced aircraft', there's nothing to suggest it wasn't human.

 

With due respect, the fact you couldn't explain it doesn't mean it's unexplainable. It just means it's yet unexplained. There's a difference.

 

My point is that usually, UFOs require a leap so large that it becomes completely irrelevant. Saying it doesnt look like anything we know is one thing. Assuming it's therefore alien is quite a leap.

 

~moo

[pink_trike]

See, this is my problem with most UFO sightings -- how do you know?

 

What I saw made me reconsider my skepticism and to consider other possibilities. I can't prove it and I don't need to. I know what I saw, I did years of research, and nothing explains it. This wasn't a weird light, an optical illusion, or a military jet. If you had been there, you'd understand me when I say that the sharp angles and the speed with which it covered vast distances simply isn't possible for anything that humans have built. I wasn't a spring chicken when I saw it, and I'm as skeptical as they come...to the point of annoyance for family and friends. There was nothing vague about what we saw...a clear cloudless night sky and sharply clear movements of red and white tightly focused lights that formed a triangle. No mind altering substances. No beliefs in paranormal or ufos that would have colored our vision.

[Moontanman]

Option #8 has totally messed up my question, this is not a debates about if they are real, we assume from the beginning they or at least some small number are real, from that we decide which possibility is most likely in that context. When you discuss UFOs you have to have limits or it degenerates into two camps of total believers and total skeptics and no middle ground is ever discussed. There are many UFO sightings that are very interesting and have huge amounts of data involved, more than enough i think to at least discuss the possibility they are real. And from there discuss some options of how they might be detected by science instead of randy redneck when he gets his anal probe. Option #8 totally negates any possible serious discussion.

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See, this is my problem with most UFO sightings -- ~moo

 

This is where the problem lies "most" most UFO sightings are hoaxes or misidentification of natural or man made object, "most". "Most" people who fall out of airplanes die. "Most" people who get rabies die. "Most" people are Married. "most" does not mean all, is it not indicative of all and if even one UFO sighting is real then it's close to being the most important thing to happen in our civilization.

 

I am well aware that most UFO sighting can be explained away and most of the ones that cannot be probably could be if they had more info but there remains a small number of sightings that simply cannot be explained even though they have an embarrassments of information from multiple observers that are trained to observe, multiple radar traces. Sightings by crew members of bombers that carry nuclear weapons and radar traces from those bombers.

 

It may very well be that even most of these are just misidentification's but there is a small number that defies explanation no matter how we look at them and these justify at least a thought experiment about why and where they could come from.

 

I did not want this to be a debate are they are real, the assumption is "if" they are real nuts and bolts craft from another civilization where do they come from and who might we go about confirming them by science.

[Variola]

ption #8 has totally messed up my question, this is not a debates about if they are real, we assume from the beginning they or at least some small number are real, from that we decide which possibility is most likely in that context. When you discuss UFOs you have to have limits or it degenerates into two camps of total believers and total skeptics and no middle ground is ever discussed. There are many UFO sightings that are very interesting and have huge amounts of data involved, more than enough i think to at least discuss the possibility they are real. And from there discuss some options of how they might be detected by science instead of randy redneck when he gets his anal probe. Option #8 totally negates any possible serious discussion.

 

 

Actually it doesn't as I voted option 8, as I believe the vast majority of UFOs have a mundane explanation. The rest may possibly be secret terrestrial aircraft that are being tested.

Your poll, and post made assumptions that UFOs re considered of non-human sources, and given that, your post was focussing on what non-human sources they could be. It also confuses things by bringing intention in mixed in with source. The source of any extra-terrestrial aircraft, and the intention behind it are two very different things.

This is by definition a science forum, you should not really be too surprised if you encounter scepticism, particularly if the poll question is ambiguous.

You could create another poll? Maybe making it really clear what issues you would like to discuss, even if they are just hypothetical, which given the lack of evidence for ET life they have to be. Or maybe a 2 issue post, discussing the possible ET not NH origins of UFOs and the possible intention possible ET visitations .

[insane_alien]

natural phenonomenon misinterpreted by humans as having some sort of intelligence behind it. we do it all the time. we used to think lightning had intelligence beghhind it for fsm's sake.

 

the question itself is flawed i believe. you say assume that ufo's are real but then try to classify them to a very specific sort but then try to argue that its a broad sort and get angry when people treat it as such.

 

if you wanted to say that asssume alien spacecraft are real and visiting earth then you should say that, not just ufo's. ufo's defy most bounds on classification because they are unidentified. that means you don't get to put restrictions on it.

[Sayonara]

Option #8 has totally messed up my question, this is not a debates about if they are real, we assume from the beginning they or at least some small number are real

The problem is that people don't tend to actually read the poll question or the poll options - they vote for what they think they are voting for.

 

You've pretty much always got to have an "other" option because you can't ever be certain that you have conceived of every option that is possible.

 

I've changed "some other option" to "some other option that assumes they're real" in the vain hope that people might actually read the words.

[mooeypoo]

As I said in the pvtmsg, Moontanman, this is a problem in a science forum because the question makes an assumption. IT's a leading question, and I am not sure what there is to debate here.

 

It's equivalent to posting a question "If unicorns are real, what color would their horn be?"

 

What would result of this debate? It's moot. We can't really debate the color of unicorn's horn when there aren't proofs to show unicorns to exist.

 

The addition didn't mess up your question, the addition made sure that the thread remains civil under the topic you intended (more or less) rather than transforming into an argument about whether or not the question is even relevant (which would have happened).

 

As with anything,you have to frame form of questions to your audience. This isn't a conspiracy UFO forum, it's a science forum. We frame questions in a certain way, even in the speculations subforum. That's just how we are.

 

~moo

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BTW, here's a few examples for your 'missing' options:

 

UFOs can be real while being man-made objects (like advanced secretive aircrafts)

UFOs can be real while being a mix of many things (one time it was man-made, one time it was natural, one time it was mistaken to be something... etc) none of which are alien in nature.

 

 

You didn't even think of including those in, even though they're VERY logical choices and they follow the "UFOs exist" premise. The question itself is flawed because you assume a single direction that, clearly, many people don't agree with.

[Moontanman]

UFOs are a very slippery subject, every bit as slippery as religion and it's even arguable they are related. i have no interest in arguing whether or not UFOs are real, i can argue that point, just as successfully or unsuccessfully depending on your point of view, from either direction.

 

I could very easily have asked the question if UFOs are not real what are they as I can ask if UFOs are real what are they. i know people who see every flashing light in the sky as an alien space ship, others who wouldn't believe it if one crashed on their house.

 

I know it's a mistake to assume they cannot be real, they are improbable but not impossible. To seriously understand what UFOs are they cannot be discussed all at once. this is because they are such a inflammatory issue, to discuss them with out it disintegrating into a war between believers and skeptics you must start out in small bits.

 

if you try to discuss the entire issue then you get too much belief and disbelief for it to make any sense. Much like discussing religion you have to set rules ahead of time, then slowly branch out as various scenarios are discussed. A rabid skeptic is just as flawed as a rabid believer.

 

i apologize for any problems my starting premise has caused, but my point was not to prove anything but to discuss the logic of the why and hows behind the issue. As in how can what we see make sense, does what we see make sense? Possibly i went about it incorrectly or i am unable to successfully translate what I want to discuss.

 

Trying to bit off the entire issue in one bite is counter productive IMHO but i believe that somewhere inside the whole issue is something real science should be looking at. If for no other reason than why humans feel the need to believe in UFOs so badly they go through great pains to convince others believe in them.

[mooeypoo]

UFOs are a very slippery subject, every bit as slippery as religion and it's even arguable they are related. i have no interest in arguing whether or not UFOs are real, i can argue that point, just as successfully or unsuccessfully depending on your point of view, from either direction.

This makes no sense, Moontanman. How do you know what UFOs are if they're things we don't identify!?

 

I don't get it. You're jumping to conclusion when a conclusion isn't warranted.

 

Do you have *any* form of proof to even SUGGEST reaching to this conclusion? That's why this discussion is so difficult. You're assuming UFOs are alien entities. We're assuming nothing.

 

I never said UFOs *can't* be aliens. But there are about a 1000 different options of what they can be other than aliens, options that are more supported by evidence, and require less conjuncture to the extraordinary.

 

UFOs can be flying unicorns from another dimension, too, but the reason we're not quite considering this option here is because stating so is so "out there" that it will require extraordinary evidence to even suggest this is relevant option.

 

My problem with the entire "UFO might be alien" bit is that we tend to forget that this is *ANOTHER* assumption that requires extraordinary evidence.

 

Occam's razor. What's more plausible - that the unidentified objects are likely natural or man-made things we misinterpret because they look weird, or that they are objects from another world, belong to an alien species that is otherwise wonderfully talented in hiding, but then flops, occasionally, with events like these.

 

It's so out there, honestly, that the 'other' option must exist, or the entire argument is moot.

 

Trying to bit off the entire issue in one bite is counter productive IMHO but i believe that somewhere inside the whole issue is something real science should be looking at. If for no other reason than why humans feel the need to believe in UFOs so badly they go through great pains to convince others believe in them.

And this, with all honesty, is an unfair claim. Scientists *ARE* looking at those objects, that's how some of them are explained. They just come up with explanations that don't involve aliens.

 

The fact the answer doesn't fit your desired outcome doesn't mean science is scared of the subject, ignores it, or is involved in some conspiracy. Many of those events ARE investigated. Most that are eventually investigated *DO* have answers, and those answers don't involve alien aircrafts.

 

 

~moo

[Cap'n Refsmmat]

I thought the point of this thread was to assume that they are[/i] real objects, rather than weird natural phenomena or hallucinations, and then speculate on what they'd be if that were the case.

[Moontanman]

We are having a problem communicating, UFO did indeed mean an unknown at least originally, in popular usage it means alien space craft. In popular usage no one says UFO unless they feel like it may well be an alien space craft.

 

http://en.wikipedia.org/wiki/Unidentified_flying_object

 

The term UFO is popularly taken as a synonym for alien spacecraft and generally most discussions of UFOs revolve around this presumption.

 

The idea was, in the context of this discussion, to assume for the sake of argument that UFOs are real alien space craft. This assumption was meant to see if logic could show the most likely scenario that allowed for the existence of real alien space craft visiting the earth.

 

I see the poll is limiting but it is limiting for a reason, we can say UFOs are Nazi aircraft remaining from WW2 but any poll has to be limited if for no other reason there is limit to the number of options.

 

I see no reason in the real world to assume anything about UFOs, real or not, ultimately we only have the veracity of the witnesses. i could post a film that shows aliens landing in my back yard but no matter how good it is it all boils down to am i lying or not. Saying I have the capability to fake and assuming I did because of that is disingenuous to me ( I do not have that capability , on the other hand i do not have such a film either)

 

I think if we can limit the scenarios to real world possibilities we can then devise real world experiments to narrow down these possibilities. thought experiments have gone on to provide real world experiments many times.

[mooeypoo]

We are having a problem communicating, UFO did indeed mean an unknown at least originally, in popular usage it means alien space craft. In popular usage no one says UFO unless they feel like it may well be an alien space craft.

 

Moontanman, popular usage in this case isn't relevant. We're a science forum , and we go by scientific-minded inquiry. For that matter, "popular" definition doesnt matter at all even for weight/mass confusion. In popular usage, many people measure weight in kilograms, even though that's scientifically totally bogus. In this forum, we try to go by relevant rational inquiry.

 

There's no shred of evidence to suggest ANY UFO to be alien visitation. If you want to ask "if aliens visit here, where did they come from" then ask that. If you want to ask UFOs, then prepare to accept answers that challenge the "common" "popular" definition that is, quite simply, baseless.

 

~moo

[Cap'n Refsmmat]

Seeing as the first line of his post was "If UFO reports are at least sometimes real nuts and bolts space craft from another civilization where do they come from?", I think the definition he wanted to use was quite clear.

[mooeypoo]

I think if we can limit the scenarios to real world possibilities we can then devise real world experiments to narrow down these possibilities. thought experiments have gone on to provide real world experiments many times.

But there already *ARE* experiments!

 

From the Min Min Lights to Norwegian swirls of light, to many others, people *DO* check these out, and they *DO* provide information and explanation.

 

You're treating this as if science is completely ignoring these sightings.

 

~moo

[Mr Skeptic]

Option 8: they are a combination of natural phenomena, man-made phenomena, hallucinations, and an overactive imagination. That said, they are real. Just not aliens.

 

Option #8 has totally messed up my question, this is not a debates about if they are real, we assume from the beginning they or at least some small number are real, from that we decide which possibility is most likely in that context. When you discuss UFOs you have to have limits or it degenerates into two camps of total believers and total skeptics and no middle ground is ever discussed. There are many UFO sightings that are very interesting and have huge amounts of data involved, more than enough i think to at least discuss the possibility they are real. And from there discuss some options of how they might be detected by science instead of randy redneck when he gets his anal probe. Option #8 totally negates any possible serious discussion.

 

Perhaps you should word it like this:

Suppose aliens are real and are/have been visiting earth. Then the aliens are most likely...

 

I am well aware that most UFO sighting can be explained away and most of the ones that cannot be probably could be if they had more info but there remains a small number of sightings that simply cannot be explained even though they have an embarrassments of information from multiple observers that are trained to observe, multiple radar traces. Sightings by crew members of bombers that carry nuclear weapons and radar traces from those bombers.

 

However, this is what is called an argument from ignorance. We don't know, therefore my opinion is a fact. The trouble is that apart from being a logical fallacy, for UFO's as aliens this also fails the "most probable explanation" test. Hallucination and imagination are a matter of known, well-tested, scientific fact. Aliens/spacefaring early civilization have not one lick of evidence showing them to be true -- only perhaps theoretically possible. Why go for theoretically possible over tried and tested? That is the problem with the idea of alien UFOs.

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I've changed "some other option" to "some other option that assumes they're real" in the vain hope that people might actually read the words.

 

Most of us understand very well what he means. I simply am not going to play the "unidentified = any explanation I choose" game. It is bad science and I wish no part in that.

 

Well-crafted polls are an important part of polling.

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It's equivalent to posting a question "If unicorns are real, what color would their horn be?"

 

It's more like, "if mythological creatures are real, what color unicorn would they be"?

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Seeing as the first line of his post was "If UFO reports are at least sometimes real nuts and bolts space craft from another civilization where do they come from?", I think the definition he wanted to use was quite clear.

 

And this one assumes that if aliens were in fact visiting earth, that we would be able to see them. It is certainly plausible that every single UFO sighting has a non-alien event as its source, even if aliens are in fact visiting us.

[Sayonara]

Well-crafted polls are an important part of polling.

Indeed.

[Moontanman]

Moontanman, popular usage in this case isn't relevant. We're a science forum , and we go by scientific-minded inquiry. For that matter, "popular" definition doesnt matter at all even for weight/mass confusion. In popular usage, many people measure weight in kilograms, even though that's scientifically totally bogus. In this forum, we try to go by relevant rational inquiry.

 

Ok, you have apoint, the term UFO does not accurately discribe what i had in mind as Alien visitation. i have no problem wiht UFO being changed to alien visitataion.

 

There's no shred of evidence to suggest ANY UFO to be alien visitation. If you want to ask "if aliens visit here, where did they come from" then ask that. If you want to ask UFOs, then prepare to accept answers that challenge the "common" "popular" definition that is, quite simply, baseless.

 

~moo

 

No problem, you are correct i should have asked if alien visitation is real where do they come from, it was a mistake to use the term UFO but I do take exception to your assertion there is no shred of evidence to suggest any UFO is alien visitation and I can back that up over and over as well.

 

There is evidence that supports the contention that a very few Unknowns are indeed alien space craft, no absolute proof but saying no shread of evidence supports some UFOs as alien space craft is simply wrong.

 

This link demonstates that your opinion of no shread of evidence is not the the only opinion out there and the opinion of some UFOs as alien visitation is held by some scientists as well.

 

http://en.wikipedia.org/wiki/Unidentified_flying_object

 

Again this is not the argument I wanted to get into since it's like arguing religion no absolute prooof and just shouting back and forth between camps of differing opinions.

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But there already *ARE* experiments!

 

From the Min Min Lights to Norwegian swirls of light, to many others, people *DO* check these out, and they *DO* provide information and explanation.

 

You're treating this as if science is completely ignoring these sightings.

 

~moo

 

No, i do know that science has investigated sightings and in some cases there was support for the alien theory, you are treating this as science has completely debunked all sightings which is not true either.

 

I am for the most part wanting to suggest a more proactive stance on looking for aliens in our solar system, waiting till someone reports a UFO is a poor way IMHO to investigate the possibilities.

[mooeypoo]

There is evidence that supports the contention that a very few Unknowns are indeed alien space craft, no absolute proof but saying no shread of evidence supports some UFOs as alien space craft is simply wrong.

By all means, bring it. Do remember, though, that since extraordinary claims require extraordinary measures.

 

http://en.wikipedia.org/wiki/Unidentified_flying_object

 

If you want to open a new thread to discuss the evidence for UFOs being alien visitation, feel free, I'll answer those there.

 

~moo

[Moontanman]

Option 8: they are a combination of natural phenomena, man-made phenomena, hallucinations, and an overactive imagination. That said, they are real. Just not aliens.

 

 

 

Perhaps you should word it like this:

Suppose aliens are real and are/have been visiting earth. Then the aliens are most likely...

 

I thought that was what I was asking.

 

 

 

 

 

Most of us understand very well what he means. I simply am not going to play the "unidentified = any explanation I choose" game. It is bad science and I wish no part in that.

 

Well-crafted polls are an important part of polling.

 

Well it was my first poll

 

 

It's more like, "if mythological creatures are real, what color unicorn would they be"?

 

No it was more like if the sighings of sea monsters were real what could have been the source of those sightings?

 

We know know many of thier sightings were in fact of now known animals or could have been inspired by known animals.

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By all means, bring it. Do remember, though, that since extraordinary claims require extraordinary measures.

 

Like I said no proof but the proof is lacking in both directions, there is no absolute proof of alien visitation nor it there absolute proof there is none, (i know you can't prove a negetive) but some compelling evidence does point in that direction.

 

If you want to open a new thread to discuss the evidence for UFOs being alien visitation, feel free, I'll answer those there.

 

~moo

 

I'll be glad to as soon as I figure out how i messed up this one.

[Mr Skeptic]

No, i do know that science has investigated sightings and in some cases there was support for the alien theory, you are treating this as science has completely debunked all sightings which is not true either.

 

For there to be support for the alien theory, you would need:

1) Evidence that alien visitors are fairly common.

2) Evidence that cannot be explained as various non-alien phenomena.

 

The strength of #2 needed to convince someone depends on the strength of #1. Given the vast distances of space, the difficulties of traveling such distances, and the fact we have not detected a planet with alien life, the probability of #1 seems to be very small. Therefore a very strong argument for #2 is needed to convince such people.

 

I am for the most part wanting to suggest a more proactive stance on looking for aliens in our solar system, waiting till someone reports a UFO is a poor way IMHO to investigate the possibilities.

 

That would be interesting. How many of these alien UFOs are spotted in outer space?

[Moontanman]

For there to be support for the alien theory, you would need:

1) Evidence that alien visitors are fairly common.

 

Why? The alien theory does not say visitors are common, in fact it says that only a small fraction of cases is relevant.

 

2) Evidence that cannot be explained as various non-alien phenomena.

 

There is indeed that evidence, quite a bit of it as a matter of fact, but as everyone says it is not absolute so it has to discounted as proof but there are many very compelling cases.

 

 

The strength of #2 needed to convince someone depends on the strength of #1. Given the vast distances of space, the difficulties of traveling such distances, and the fact we have not detected a planet with alien life, the probability of #1 seems to be very small. Therefore a very strong argument for #2 is needed to convince such people.

 

I understand the evidence of proof has to be very strong but so far it is not absolute, no pieces of aliens, no pieces of alien space craft but there is a large body of evidence that make more sense as alien space craft than it does anything else.

 

 

That would be interesting. How many of these alien UFOs are spotted in outer space?

 

Actually some have been but that is not what I would propose be looked at as part of an investigation. I think and this is just my opinion but I think #1 in my sadly flawed "poll" is the most likely possibility and if we wanted we could look for evidence of this.

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Actually #8 as it has been modified is ok as part of my poll if people would indeed say what their "other" idea is.

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Ok, lets end this, this is my thoughts on the possibilities in my poll.

 

#1 They are travelers from another star colonizing asteroids

#2 FTL travelers who just stop by to check us out and leave

#3 Remnants of an early human civilization colonizing asteroids

#4 Remnants of a pre-human civilization still present in the solar system

#5 Time travelers from our future

#6 Travelers from other dimensions - alternate worlds

#7 Supernatural beings we might as well call Gods or God.

#8 Some other option that assumes they are real (please specify)

 

 

#8 seems to be the most popular and since so far no one has actually given an example of #8 I'll ignore it.

 

#5 Would seem to require something even more remarkable than aliens. Using one outrageous claim to support another is less than effective in an investigation of anything.

 

#6 is pretty much the same as #5

 

#7 Is strangely connected with the subject but also another debate altogether. i wish i hadn't included it, it should have it's own thread at least.

 

#2 Is probably the most believed of all of these scenarios and while not impossible does present some real problems with what we think we know about the universe.

 

Even if aliens have Star Trek type technologies the idea of simply stopping by to check us out from interstellar distances would difficult to support as a real contender here. assuming that aliens would be able to violate what we think are the laws of the universe and want to stop by for no apparent reason other than to confuse us seems at the very least a huge waste of energy as well as time. I will admit we might not understand the motivations of such aliens but still the energy requirements of such visits is mind boggling.

 

#1, #3, and #4 are interesting in that they do not require any violation of the physical laws of the universe as we know them.

 

An advanced civilization would not seem to need planets, but previous civilizations (#3 and #4) should still be able to colonize the Earth. it difficult to see any previous earth civilization not continuing to have some presence on the earth.

 

#1 Colonizing the resources surrounding a star would be far more productive than trying to use the gravity wells of planets, a strange planet would be unlikely to be useful for many reasons, everything from trace elements to biological quirks that render the biology of a strange planet useless or even dangerous are quite possible if not likely.

 

But a slower than light colonizing effort of the galaxy by using the resources orbiting a star makes almost any star usable to the aliens. such a colonizing effort could in theory occupy the entire galaxy in a few million years, a blink in cosmic time.

 

Large earth type planets would be curiosities but not the reason or central effort of any colony effort. If a planet of a star being colonized had life, especially intelligent life it make sense for aliens to visit occasionally to check out local conditions much like we explore the remote places on our planet for scientific curiosity or to monitor the progress of such a civilization because eventually they might have space travel too.

 

But possibility #1, #3. and #4 do present us with another possibility, we could detect them. such colony efforts should leave detectable signs of their presence. large industrial sites might be invisible from the earth via optic telescopes but they should stand out in the infrared.

 

if we did a infrared survey of the solar system infrared anomalies should be looked at closely and one possibility could be aliens! a unusual infrared signal in places where the conditions should be very cold would be interesting on their own so the survey would not a be a waste of time.

[Mr Skeptic]

Why? The alien theory does not say visitors are common, in fact it says that only a small fraction of cases is relevant.

 

If the chances for each inhabited planet that an alien would visit from a different solar system and be spotted by the natives in a pattern similar to UFO sightings are less than, say, 1 in a million, then an event that has a 1 in a hundred thousand chance of having some other explanation, such an unlikely explanation still makes more sense than saying it was an alien. Nevertheless, to a "believer" who thinks the chance of said alien visit were 1 in 100, that same evidence would be seen as nearly irrefutable proof (1000 times more likely than any other explanation).

 

So the strength of proof required depends on how likely the event is supposed to be. Also, multiple different events need not add up multiplicatively for this purpose (ie two 1 in 100,000 events are not as good as a 1 in 10,000,000 event).

 

Another problem is that at small enough probabilities, falsification is a comparatively significant probability as well.