Fermi paradox - if intelligent life is common in our galaxy why do we see no signs of it?

well thats the simple question posed by fermi which has caused alot of debate over the years.

Anyone here have a really satisfying explanation as to why we see no signs of technological civs? I'd like to hear them if you do

In case you haven't noticed...this universe is quite large. Infact, trying to comprehend the size of the universe is a task in itself. There are 8 planets (Pluto is out right?) in our solar system, revolving around a star. There are a more than a 100 billion stars in our galaxy. There are more than 100 billion galaxies in this universe. Now...when you take all that into account, does it really puzzle you why we havent come across other intelligent civilization (unless ofcourse we have, but arent privy to such things)

Im gonna take this further and reverse the situation... how can you be so sure there isnt another civilization sitting 256 million light years away asking itself...where is everyone else? Id imagine, and ofcourse this is all conjecture, that a lot of civilizations find themselves in a similar situation as us. And when I say a lot, I mean a lot. Im one of those people that believes that not only are there other civilizations, but that they number in the hundreds of millions. And in a universe as mindbogglingly large as ours, its just not that far fetched...well, to me anyway.

[edit on 29-8-2007 by 3_Libras]

Maybe it's rare for a civ to get as far as we've got without destroying them selves - or being constantly fractured into smaller groups that have to devote all their time and energy into other things like battles, or living on more unstable planets.

On the other hand there could be an intergalactic club with membership criteria, which we either haven't met yet - or are simply incapable of meeting.

I've often though that through history at some points we have been given a nudge in the right direction, and these nudges have been getting more frequent, so I'd like to go with the intergalactic boys club please

why is it very hard to comprehend that there are other civilizations? I mean
if you think humans are the only species out there you are very wrong.
We can't even see what is on Jupiter, yet we want to rule out intelligent
civilization? that is hypocritical.

I'm currently reaching the end of The Intelligent Universe by James Gardner. This mentioned that one of the reason for us not detecting them is that we simply don't have the technology to do so... even if they right here amongst us. For example, alien probes could be invisible and/or nanoscopic in size.

ok first lets make it clear i think there is other civs in the universe but its unlikely we will ever detect them if theyre outside our galaxy. Realistically its about our own galaxy and if they exist here or not.

to address a couple of points above.

In theory the experts say intelligent technological civs could have arisen as early as 4 BILLION years ago in our galaxy.

If we look at our own civ and technology we can imagine some of the things we may acheive in the future. Nanotechnology for one. Ill give an example.

1.Bracewell probes- featured in the movie "contact" - self replicating probes dispatched throughout the galaxy with the purpose of detecting civs and sending a signal revealing ET presence, it could take as little as 10 million years to send a bracewell probe to every single star in our galaxy- that means in theory you could have covered the galaxy 2000 times over- but it seems there are no probes at least not within around 40 light years of earth.

2. Same with intersteller travel- if near speed of light travel is possible a civ could colonize every single star in the galaxy in around 1 million years- again this means that civ could have completely colonized the galaxy thousands of times over- again we see no sign of that particualrly here on earth where weve had a nice stable planet for 500 million years.

is it a long shot to say evry single civ in the galaxy in the last 4 billion years has not reached that level of tech? ever? remember to not have these things you have to assume evry one of them did not do it for soem reason.

[edit on 29-8-2007 by yeti101]

yeti101, just wanna add something...

You talk about the probes. The so called "experts" in this field as far as Im aware have hinted that these probes wouldnt go looking for planets to inhabit and look for life, but would settle on the nearest moon of a particular planet. When that probe was discovered by an intelligent civilization, say for example us going to the moon, it would signal back that there is intelligent life there and etc. Apparently its the most efficient way of flushing out civilizations which are "worth it" so to speak

i would say it makes more sense to have a probe sit in a solar system and look out for radio singals coming from one of the planets- when it detects artificial radio signals it starts transmitting . Thats what happened in the movie anyway

Originally posted by yeti101
i would say it makes more sense to have a probe sit in a solar system and look out for radio singals coming from one of the planets- when it detects artificial radio signals it starts transmitting . Thats what happened in the movie anyway

Hmmm...Im not so sure. It would be very naive for a civilization to use radio signals to search for life (kinda like what we do). Another way is to somehow be able to detect the amount of waste emitting from a planet, which gives off a radiance, heard that by a physicist, very good idea I thought

well assuming theyre advanced enough they may hve many methods of comms besides radio waves. But i think they would know about them and thus search for them especially among primitive civs like ours

if they have so much tech they must know about radio waves and the likelyhood an early civ may use them

[edit on 29-8-2007 by yeti101]

Yeah true, but its also how we send out radio signals and are left there thinking that there is nothing out there because no one has replied. Very ignorant move by mankind, but I guess theres not too much more that can be done for now.

libra i think the reason we have not detected a signal is becuase nobody knows we are here.

we're the new kids on the block our leaked radio signals have only travelled max 80 light years. Its unlikely theres a civ within that distance. 1000 light years is more realistic. So i dont think we will receive a direct signal for a few thousand years.

we may detect leaked signals if our tech develops enough though, still leaves us with the probe absence problem- maybe there are probes we just havnt found them yet

[edit on 29-8-2007 by yeti101]

Great discussion, Yeti!

On the Bracewell probe, I get your possible exception about being cautious, but I think they'd be capable for producing a highly stealthy, low-impact type of probe.

For instance it would very small, low observability, and after sending the homing signal or result of the probe, would disintegrate into common non-polluting elements, like carbon and hydrogen.

In fact I'd expect that it would almost be built like a virus. Self-replicating, extremely resistant to time and space and radiation. Of course it wouldn't infect anything, it would just report, I'd think.

There are probably lots of sentient civs out there, even in our galaxy. I just think nobody's been able to get off the planet and become truly space-faring.

Probably have millions of type 0-.8 civs out there like we are, passively listening, but trapped on planet by one thing or another. Technology, higher gravity, low water, sparse resources (in comparison), bodies too big or too small, not resistant to G-forces, mild radiation, etc.

In fact using Fermi on a Universe scale, I think if there were a few Type-III-IV civs out there that they'd also have colonized the other galaxies by now. I mean once you are able to go to another galaxy as simply as walking out your front door (think stargates), then life would be expanding exponentially, just like multiplying bacteria.

Anyway, thumbs up!

* they are us in the future
* they were here and we are their experiment - their little zoo
* universe is to big and there are no means whatsoever to travel such distances
* they are sending communication signals - but we could not grasp it
* they have no desire to communicate
* they suffered some cataclysmic event
* they do not want show where they are located - who knows what sort of predator aliens are watching
* they are asking the same question: 'are they alone' - coz they are on the same level of civilization as we are
* they are even less developed than we are
* we are the first
* we are alone in the universe
* they do not find us interesting
* they do not want to interfere at this moment
* we have been overlooked somehow
* the universe size to exist - and we will know that far in the future


[edit on 29-8-2007 by blue bird]

Originally posted by blue bird
* they are us in the future
* they were here and we are their experiment - their little zoo
* universe is to big and there are no means whatsoever to travel such distances
* they are sending communication signals - but we could not grasp it
* they have no desire to communicate
...

Pretty good list. I'd go over each point but that would make a quoting nightmare.

Future us - possible, if you accept the common type as the standard Grey. Other bizarre types, (reptilian), requires more explanation.

Experiment - possible. Requires some explanation as to why they left the experiment untended for so long (to us)

Universe - Big. Well the Fermi Paradox mainly refers to our GALAXY and not the whole Univers. But yeah, it's big. Also, cold, dark, vacuum, radiation, etc.

Can't receive or decipher signal. Well we hope that 'advanced civs' would recall their earlier primitive radio signals and send out a beam tuned into something immutable, like the resonance frequency of the hydrogen atom.

No Desire - This is an interesting possibility and I just thought of an exception to the Fermi Paradox.

Suppose (excuse the pop culture reference) that there is a race like the Borg of ST:NG. All the spacefaring civilizations know about this and thus have evolved their technology to have them cloaked so the Borg can't find them. Thus not only could we NOT detect them, they might be en masse, actively preventing detection (but not from us, necessarily).

Anyway, as I said, good list. There are probably even more, such as they are 'dimensional beings', or even wilder, they are 'somehow created (given substance?) by our imaginations', yada, yada.

Nice topic!

Yeti: I believe you are correct in the sense that at least one civilization in the past 4 billion years must have had the means to be able to colonize the entire galaxy many times over.

The only answer i can come up with is that the Galactic habitable zone is much smaller than we believe. Our solar system is in a quite isolated galactic environment. but it is close enough to the centre of our galaxy, so that their has been the right amount of supernova explosions in our areas past to allow for heavy enough elements to allow life.
For example, too far out on the outscurts of our galaxy there is not enough heavy elements for life, but too close to the centre of our galaxy, there is to much radiation for intelligent life.

Maybe our solar system and a few of our neighbours are in a rare galactic green zone. Maybe an advanced civilization can detect these green zones in our galaxy, but the sheer distance that the civilization has to cover to before it can colonize another planet may effectively deter any expeditions.

There maybe still be hundreds of these green zones in our galaxy but because they are so far apart it greatly reduces the number of systems a civilization can colonize, therefore the speed a civilization will colonize the galaxy will be greatly reduced, maybe reduced enough so that they still have not reached us, or maybe we are to isolated that they dont care about us for the time being.

Although this doesnt explain why the civilization wasnt able to just make an unstable environment, stable for them to live, vastly increasing the number of stepping stones making it again possible for them to colonize the entire galaxy many times over.

Very interesting to think about.

Originally posted by Now_Then

On the other hand there could be an intergalactic club with membership criteria, which we either haven't met yet - or are simply incapable of meeting.

Well of course there is an intergalactic club. Why else would the NWO be pushing for a one world government, a one world economy, and a one world religeon? Duh! it's so we can join the intergalactic big boys club and then exponentially expand our knowledge. Do you actually think that another civilization that has the technology to travel here in the first place would seriously give us the time of day when our world is in constant chaos. Sure we can build space shuttles, probes, and make nuclear explosions but face it we are still a very primitive world. In the grand scheme of things we are still in preschool.

Hessian , you make a good point there could be bigger contraints than we think on intelligent life developing and travelling. I think about the possibilities but keep coming back to the same conclusions

1. Intelligent life is rare
2. All technological civs eventually destroy themselves

when i say rare there could be 300 billion civs in the universe but that would mean 1 per galaxy- if so we're unlikely to ever detect 1. which is quite a sad thought


[edit on 30-8-2007 by yeti101]