We will most likely have cataloged and observed hundreds of thousands, if not millions, of exoplanets before we physically reach the nearest star. Unless and until we can travel from system to system at an appreciable fraction of the speed of light (> 10%) then the only practical option available to us for exploring the galaxy is to continue building bigger and better telescopes.

Assuming superluminal travel remains science fiction, it will take thousands of years to explore more than a few light years in any direction, but once we start to seriously toodle around the solar system, then we can start to put up some serious hardware that will be capable of direct observation of exoplanets, including looking for telltale signs of life and technology. So even before we set foot outside our own solar system we should have a very good idea of what's out there, a least within a few dozen light years, and maybe more (I have no idea what the limits are of suitably massive--and I mean really massive--space-borne telescopes... if anyone would care to comment).

Of course, what we will be able to do, can be done (and may already have been done) by other more advanced civilizations (if they exist). We are possibly no more than a couple of hundred years away from being able to build a comprehensive catalog of planets ourselves, so imagine what could be done 1,000 or 2,000 years hence.

Even if we don't discover any other technological civilizations, we should at least be able to start narrowing down the values of a couple of the terms in the Drake equation.

And fears over sending radio signals to other worlds seem a bit nonsensical when you consider that advanced aliens dozens or perhaps even hundreds of light years away can probably already see that Earth is home of abundant life. And anyone observing the night side of our little planet, at least the light leaving it within the past 40-50 years, will probably figure out that something unnatural is making that sodium glare! We already betray our presence to those who care to look in our direction.

Indeed. Our radio messages can only reveal our presence to a civilization similar to ours, more advanced civilization would know of us already and less advanced don't have the technology needed. Since our current technical phase will be very short (we either become more advanced or screw up), the chance of having a similar civilization in the direction of the signal is infinitesimally small.

It should be obvious that a xenophobic civilization which wants to destroy us would be very keen to find every possible civilization and therefore would already know of us, no matter if we sent radio signals or not.

__________________
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman

Perhaps we are already in such. Maybe the sheer size of the galaxy, and our currently limited intellectual and techological abilities keep us ignorant. The ant colony in my backyard doesn't know it lies in the jurisdiction of the United States.

I think the fallacy of the Drake equation is that it considers the visible universe as a whole and so it must to generate statistics favoring the discovery of intelligent life. However, if one considers a more practical universe, say one that is within a few hundred lightyears (after all we have only generated radio waves ourselves for less that 200 years), the chance of finding intelligent life is almost nil in my opinion.

-Veeger

Whether the Drake equation is meaningful or not (& it seems logical) there are way too many unknowns in it.

The average rate of star formation seems like it could be deduced from number of stars versus age of the galaxy/universe but any change from a steady state of growth of the galaxy (eg. collision with another galaxy) would alter the figure radically. Or if it turns out our theories for how galaxies came about get revised...

How many have planets? 15 years ago we knew of precisely one. Now it seems they're everywhere.

How many of those planets can potentially support life? Who knows? Again we have a sample of 8 (used to be 9) to choose from & we're not even sure yet there aren't strange forms of life around our backyard.

How many develop life? Same sample size.

Intelligent life? We have only one planet that we know has life & it definitely went on to develop life with at least a semblance in intelligence. That could point to ALL planets that have life will develop intelligence or may have nothing to do with how many could.

and so on...

In fact, the Drake equation is rather useless now, due to lack of information to be able to apply numbers anywhere in it, (except for a tentative figure for star formation) and useless in the future, because by the time we can fill in the numbers we will already know the answer.

__________________
* Never doubt there is Truth; just doubt that you have it!

As for evidence of advanced civilisations, should we consider the anomalous presence of structures here on Earth?

Apart from a Sphinx that exhibits rain-caused weathering that implies a date far in excess of 4500 years age, or the weathering ridge around the Great Pyramid where the limestone facing used to be, or the sophisticated working of granite by a civilisation we claim to have had only copper or at best bronze tools, there's structures around Japan, India & Mexico that are under water that we know has been there at least 10,000 years.

If we can't recognise the evidence in plain rock of an advanced society, (& most probably one made by humans) what chance do we have of recognising signs of ones that may have an entirely different basis for civilisation than we have?

__________________
* Never doubt there is Truth; just doubt that you have it!

It's a good point, imo. While we as a species probably have been exhibiting signs of advanced development for more than 10,000 years, its only within the last moments of time that we have been able to demonstrate that advancement beyond the confines of our atmosphere. It is clear that our efforts to find intelligent life must of necessity focus on races with very similar technological skill as our own. Like you point out, we probably would not recognize any other.

Very similar to our own - Hm. Would we recognize our own, human, future technology a thousand years from now - if we "saw" it? (provided we do not screw up)

People from the 19th century would have difficulties to see what they'd look at, if they were suddenly here in 2008.

That two civilizations from different solar systems should be so very synchronized in this sense (at the same level of technological evolution) so that they really perceive each other, seems unlikely...

That's exactly the point TeaBinge. Unless the other civilization is very similar to our own, I doubt we could find it or recognize it as advanced.

-Veeger

There's also the issue of maybe they are not only out there but they've come to see us. There's quite a number of the UFO sightings that haven't been adequately explained but the campaign of disinformation & labelling prevents a serious look being taken. After all, even if all the viewers are hallucinating, there's something going on among millions of people around the world.

We can't even agree that a race that is evidently self-aware, that displays curiousity & humour, & that will use tools to solve new puzzles is intelligent; if dolphins can't make the grade, what chance the slimeballs from Aldebaran who communicate with farts?

__________________
* Never doubt there is Truth; just doubt that you have it!

Since the world we live has overwhelming amount of information, human brains must make lots of simplifications and crude assumptions in order to make the world understandable. Which means we do a lot misinterpretations, especially if the phenomenon we are observing is not familiar. And no one of us has an unchanged memory, the more we think about our experiences the less truthful they become. You don't have to be at all funny in your head to see things that don't really exist or remember something that hasn't happened.

Some sightings are no doubt rare or even unknown natural phenomena, but Occam's Razor is not kind to the extraterrestrial hypothesis.

Have you ever wondered, why amateur astronomers don't see UFOs even though they observe much more the sky than a casual person? It's not because they're afraid they're going to be ridiculed. Of course, you can always make the counterclaim that they misinterpret genuine alien spacecraft as natural phenomena.

UFOs as extraterrestrials are the modern equivalent of elves and angels. People believe to them because they seem so plausible. Humanoids are an interesting scientific phenomenon, but only from psychological and sociological sense.

And this post is off-topic.

__________________
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman

You hit the nail on the head here. What is actually intelligent life is actually a very important question. Sometimes I do have serious doubts if there is any intelligent life here on Earth because bottlenose dolphins don't seem as bright as they're pretending to be.

__________________
Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool.
-- Richard Feynman

Who's to say that we are not the most intelligent beings in the universe and that everything else doesn't have the ability to make contact ?

__________________
Thank God for magnetism.

That would be a major ego boost.

And if we are the largest life bearing planet- that makes us stronger than them too.

We could be...

WHY ARE YOU ALL ASSUMING THAT THEY WOULD WANNA COLONISE INTERSTELLAR SPACE?What if the long before us created a cyberspace on one supercomputer on their home planet and need almost no resorces?

But if O2 is as deadly for them as HF for us?
They would try to explain it by natural phenomenon, because surely nothing can survive such a poision as molecular oxygen .
My solution - they never survive to a stage where interstellar travel is possible, just look at how evil and war creating are our own spieces on our home planet.

You have sorry, but pathetic arguments, how can you pretend that they would have the same reasoning as us.Maybe they center on their own planet and their own survival.

What the hell, WE ARE ADVANCED FOR A CENTURY HOW DO YOU EXPECT TO FIND ANYTHING UNIVERSE DO NOT OPERATE ON OUR TIMESCALES!!!

And I would expect beings capable of visiting the whole galaxy to ERASE AND COVER THEIR TRACKS.

Excure me, you reasoning seems to be moronic to me, aliens are NOT humans.

What if they live as little nano sized quantum computer brains in dust?

You expect them to use their fragile bodies if they can colonise 100000 light years of space.LOL!!

And you expect beings capable of interstellar travel to communicate with us?This is about as ridiculous as if we would try to speak with snails, we are primitive animals for them if they really can colonise galaxy.

And tell me would you bother to build some spaceship just to wait 50000 years and came to a deserted planet? You are throwing 10 percents of c but you have no idea actually how fast it is.You will need tredmenous amounts of energy to do even 1/50 of c if antimatter cannot be mass manifactured.

You are pushing the borders of ad hom!

__________________
Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

Sorry but it seems totally really ridiculous to m