Maybe they just haven't looked our way yet? Maybe they know we're here, but the vast distances aren't easily traveled (or are impossible to travel)? Maybe their race was dying out as we were starting out? Maybe we're at the top position (ie, are the most advanced) in our galaxy? Maybe we really are all alone? Maybe they already did 'check us out' and we literally 'freaked them out' (let's face it, we can be a brutal bunch)? And yes... Maybe they are just dumb or what?

There's just no way to really know now, is there?

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An open mind is like an open window...without a good screen you'll get all sorts of weird bugs!

It didn't address mine.

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I say there is an invisible elf in my backyard. How do you prove that I am wrong?

Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

I think there is always a think you must ask a person using the phrase 'intelligent life'. How intelligent are we talking? Usally ppl are talking about those that make technology, which is only humans as we know it, but i would surely say a cow is intelligent - maybe not much intelligent, but a monkey then. Personally i use the phrase 'highly intelligent' for those that develop technology. Monkeys are close to this phrase now, as it has actually been proven that they use tools. The question is how long it will take before they will develop this intelligent into something better.

+10k from me, i believe that is what i usally get when doing Drake's equation.

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"The world is a fine place and worth fighting for." (Ernest Hemmingway)

Boring.

It is much more interesting to speculate. Explore possibilities. Generate ideas. Eventually one will prove to be correct. It may be a matter of luck as much as anything else, but whoever turns out to be right will win accolades and recognition, ticker tape parades, and dates with beauty pageant contestants...

Or so a guy can dream, can he not? That is what this is all about. What are the ETIs like? Where are they? How many are there? I guess it is worth noting from time to time the cold hard reality that no one has the slightest idea. Nevertheless, discussion points out novel areas of research. Suppose the ETIs built Dyson spheres. We might wish to peek at super giants radiating in the deep infrared, just in case. Or, how would anyone think to search the 21 cm band if it weren't obvious? Or perhaps--is EMR really the most economic method for interstellar communication?

Pasha, you might want to read through the thread. There has been a great deal of speculation. The specific issue being discussed here is an absolutist position by WT, who has responded to few questions on his position, with even fewer substantive answers.

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I say there is an invisible elf in my backyard. How do you prove that I am wrong?

Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

No, there really is no way to know why ET hasn't contacted us or been detected by us. But we can access some probabilities, establish lower and upper limits to various quantities. It doesn’t have to be uninformed speculation.

For instance, what are the chances that a technological civilization exists in our solar system except on Earth? I think we can say, “Not very likely at all.” Something we couldn’t have said even 100 years ago when Percival Lowell was mapping the canals of the dying civilization of Mars.

Admittedly, there might be creatures in the ocean of Europa developing amazing technologies at this very moment. But what are the chances? One in 10,000 would be a very generous estimate in my opinion. At the very least, I think we all could agree it’s highly improbable.

We can move out a little further, say 50 light years. There are about 1,000 stars in the sphere surrounding the Earth out to 50 light years, representing about one in 400 million stars in our galaxy. So, if the probability of an advanced technological civilization existing within 50 light years of Earth were 50%, and leaving out unlikely places like the galactic core and metal poor regions, we would expect to find about 100 million such civilizations in our galaxy.

Since I think most of us would be satisfied with a probability considerably lower than 100 million, I won’t bother with the argument that there are no technologically advanced civilizations within 50 light years of Earth. Perhaps someone could suggest ways in which to lower this 100 million. No speculation, but an assessment of probabilities based on the information we have today.

If, for instance, we were able to establish the probability of an advanced civilization within 100 light years of Earth were 1%, that would reduce the probably number from 100 million to 250,000.

Bob

I suspect thou art not gainfully unemployed. If you were you would understand. This is not back peddling, my friend.

I did post the answer. Is there a problem with reading the pdf files?

There is a lot of pages now to slush through. Please IM me the question and I will post the answer here.

Actually, I'm in agreement with you as to being able to narrow down the odds, so to speak. My 'educated guess' for technological civilizations in our galaxy (of all levels, some more, some less advanced than ours) was only a few hundred...maybe. But, this is still just a guess based on what we know right now, that could, and likely will, change as we begin to gather more evidence. The jury just ain't in on this one yet!

My 'beef' (issue) is that there are some who think that they know 'the answer'. Some say they know for sure that ET is banging on our door and that we're just too dense to notice. Others say they know for sure that we are all alone in the galaxy, and that NASA continues to look for signs of life just to placate the ET believers, secure funding, and protect their jobs.

Frankly, either of these extreme positions seem unwarranted given our present level of knowledge...see what I mean?

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An open mind is like an open window...without a good screen you'll get all sorts of weird bugs!

So, has anything changed in the few months I've been gone? Any useful new arguments? Are my arguments coming in handy? just checking.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

OK, I just read the last page and I see little has progressed, and may have regressed. Lemme opine on some issues.

First, Aliens may be couch potatoes. If they are advanced enough, they may have unlocked all the secrets of classical and quantum physics, created robotic workers, and be bored. Thus, I would expect them to engage in entertainment like beer and tely.

Second, Sol is not on the outskirts of the Milky Way. It is smack dab in the middle of the rich suburbs. The radius of MW is about 45kly and Sol is about 26kly from the axis, a little over halfway out. Considering that the center bar is about 25kly wide, we can conclude that sol is about 13kly from the city limits.

Third, I think some people are thinking too one dimensionally about colonization. I think I addressed it 20 pages ago, but I'll continue here. Singular serial linear progression of one colony to one more colony is a very large assumption and unlikely to be true. Let's look at the formulas for interstellar expansion.

The Linear Adam and Eve Formula: This assumes that as soon as a colony lands on a suitable planet, they have to start over from scratch, probably "teraforming" and/or reinventing materials and manufacturing science, nuclear physics, establish commerce and trade in order to create a foundation able to afford to send another colony ship. While this may be part of an expansion culture, it is my no means the only method. The serial nature of this is a very low efficiency format for expansion.

The Parallel Adam and Eve Formula: This assumes that multiple colonies will land on multiple suitable planets and start over from scratch, yada yada yada same as above. There are two subtypes to this: lockstep and continuous. Lockstep means that all colonies launch their colony ship at about the same time, e.g. every 1000 years. Continuous means they they launch their colony ship at the specified interval, which may or may not be coincident with an other colony. This would seem to be a more likely scenario, which is not limited to one colony ship per intelligent species per time period. However, this format is still serial and efficiency is not increased, only the number of inefficient producers.

The Battlestar Galactica Format: This is a single colony that never settles, but is in constant motion, only stopping for supplies as needed. This might be more likely since the economy of the fleet/worldship would be established and stopping to create a separate planetary colony would tie up a lot of resources and take a while to establish. Someone once said that once a species learned to live in space, why would even need to establish world based colonies and ecosystems? This format would allow the species to "cover more ground" and increase the chances of discovering something interesting, like a pysical phenomena or other life.

The Multiple Battlestar Galactica Format: Just what it sounds like. Several of the spacefaring colonies traveling at the same time in multiple vectors. This increases the potential for contact dramatically. Might also be referred to as the Indianapolis 500 format, because they don't stop moving unless they need to make a pit stop, but they don't all stop at the same time.

Let's pause for a moment and consider why an intelligent species would do this? Well, one reason may be they are bored and want to experience new things. Traveling at relativistic velocities would appear to extend life, so they could witness more astronomical phenomena or life forms during a single lifetime. This may be useful in advancing knowledge for the rest of their species. You would not get the same type of brain drain an institution suffers when top researchers die. Consider what we would learns from Einstein if he had been put into a relativistic ship and been able to stop back periodically to pick up a new computer and learn of new discoveries in quantum mechanics from relativistic life extension.

The Dandelion Format: This is where a colony ship sets up a colony on a world without starting from scratch. Maybe they stay in orbit the entire time or maybe they build bubble cities, but they don't need to "terraform" the planet in order to prepare and launch more colony ships. Like a Dandelion they can propogate almost anywhere. Also like a dandelion is their massive reproductive ability, launching not one, but many colony ships at a time and/or continously.

The Tree Format: This is a combination of the Adam and Eve and Dandelion formats. A colony sets up a colony and sets up bubble cities while also slowly terraforming. Like a Dandelion, it can start sending out more ships in short order and in quick succession while also making the world more livable from scratch like an Adam and Eve. This would result in long term colonies as well as vast numbers of second order colonies in a short timeframe.

The Point Source Format: This is where an intelligent civilization on their home planet sends out not a single or occassional colony ship, but instead launches many and frequently, in lots of directions to lots of distances. Maybe one ship stops at a planet in one star system 10 LY away, the second would go 100ly before stopping, etc. This would be one of the quickest expansion plans because each new colony is independent and unreliant upon any earlier colony after it leaves the homeworld. The only limiting factors are the durability of the ships and their velocity. If we assume light speed travel, this means that the initiating civilization might be establishing colonies at the farthest reaches of MW within 100,000 years if they send from one edge to the other edge. If they are near the center, then they could have colonies at the edges within 50,000 years. (if you want to assume subluminal speeds, then just do the appropriate math, but it is still a relatively short timeframe.)

The Cascading Point Source Format: Similar to the Point Source format, it includes the colonies eventually sending out their own colony ships in a similar manner as the point source. While this does not increase the speed at which species reaches their farthest extent, it does increase the rate at which the volume of MW is filled --comprehensively explored and subsequently colonized.

It is more likely that a species would use a combination of all of these. But it is easy to see that the quickest rates of expansion would have seen MW colonized over and over again in its current lifespan. And if some of you are concerned about how much it would cost then don't. It would not be something would have to be paid for but something that would have to be done. All you need to do is determine the number of man-hours (individual member of a species work performance-hour) of labor for the production of materials to determine the minimum amount of turnaround time for a colony to reproduce a colony ship. Assume a communistic model or a capitalistic model or whatever you want as long as you get an answer, then use it as the minimum turnaround. Just don't assume they won't do it at all, for that is avoiding the question, and the assumption is already made that they will act in some manner. If nothing else, their job would give the worker a purpose in life and it would provide job security.

Edit to add:
I made up those format names, they may or may not be called that by other parties.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Then for all practical purposed they are not intelligent. Any real intelligent species would understand the necessity to leave the planet for the most fundamental of all goals of life: To survive. This is because our environments are temporary.

Be specific. What are you talking about?

Is this it?

Yes but we are limited in energies and abilities to conduct research. We have to pick our battles. This battle is without hope of success.

This optimism is not backed up by the latest scientific study. How many intelligent civilizations in the Milky Way?

As far as regarding any of these scenerios as happening, what are your opinions of these articles?

Fermi's Paradox on The SETI Institute Part I
Fermi's Paradox on The SETI Institude Part II
Fermi's Paradox on The SETI Institude Part III

You assume too much. Just because I described a scenario where they sit on a couch and watch TV does not mean that the couch is not on a space station or starship. Please think before you post.

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"What you think you thought you saw you did not see." Agent J, MiB - Manhatten Bureau

Of course! A couch on a space station or starship! My mistake! I apologise.

Yes, I should have thought of that before I made a post.