There might be extra-terrestrial life out there, but it doesn't have the capability to send out signals (radio broadcasts, radar signals etc.) into space that can be picked up by instruments on Earth.

Greg Bear Posited this scenario. He called it the Hawk and dove. interstellar Civilizations that are doves act much like us. Broadcasting their noise signals into space.
Hawks act silently out of fear or gile. they communicate but in ways that aren't perceived by what we consider normal means

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In a rich man's house there is no place to spit but his face.
Diogenes Of Sinope

Some signaling technology other than the electromagnetic one we use is always a possibility. Limiting the field to electromagnetism, even our own digital signals sound increasingly like random noise. Such signals with an extraterrestrial source might be impinging on SETI receivers right now and pass unnoticed We could try to guess at how to decode extraterrestrial digital signals, but the odds of success seem pretty long. Hailing signals intentionally sent our way will probably be very simply modulated and easy to detect. Michael

Hailing signals intentionally sent our way will probably be very simply modulated and easy to detect. Michael

It is assumed that any species intentionally sending a signal wants to be heard and will be sending a simple signal (look here.)

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Do you think it's also possible that we are the most advanced civilisation at least in this part of the galaxy, why do experts keep saying that intelligent life out there is likely to be more advanced than us?

Do you think it's also possible that we are the most advanced civilisation at least in this part of the galaxy, why do experts keep saying that intelligent life out there is likely to be more advanced than us?

That's the problem, there's far too many assumptions to make. Sure, we could be the most advanced civilization (that's not saying much for the rest of the galaxy).

Regardless, that's no reason to stop looking because the opposite assumption is almost as likely to be true.

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It's most likely that if we do find anything it will be a more advanced civilization. If you think about how far away the nearest stars are and how long it would take for signals to get to us, it's easy to see how that civilization is likely to be more advanced than us by now. (Assuming that civilization still exists.)

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I should add that if there are less advanced civilizations out there it's not likely they are sending out any radio signals that we could detect. The fact that we can't detect them doesn't mean they don't exist.

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Light is a cosmic slug.

It may be ok for communication within a planet but not between two stars. The only signals from aliens we will ever get via radio is probably from some poor devils at the same level of technology as us - difficult but it explains why we haven't "heard" from them yet. Which is great to start with... We could even crack the message they send... Probably the same kind of bits we once sent to M13.

Tachyons would be better, if not perfect.

Too bad it's still a theoretical particle... Wormholes are good too. They could be used not to traverse but to send light in a faster way. The galaxy may be wired with them as we do here on Earth with optical fiber, this way you can send a message just to the ones you want, thus keeping your privacy.

Gravity waves are another possibility... to find civilizations from paralell universes.

My guess is: we're gonna find the Higgs Particle before ET.

Still... I think it's a good idea to search in whatever way we can (afford), that's why I participate in the data crunching.

I hope the LHC doesn't discover any more defects when it get to full power, that could get messy

Do you think it's also possible that we are the most advanced civilisation at least in this part of the galaxy, why do experts keep saying that intelligent life out there is likely to be more advanced than us?

That's the problem, there's far too many assumptions to make. Sure, we could be the most advanced civilization (that's not saying much for the rest of the galaxy).

We know that the outer edges of galaxies are younger than the centers. Our solar system is on one of the outer spiral arms so we're very young compared to most of the galaxy. A more advanced civilization would be older than us and the majority of the galaxy is older. I think that's why they say intelligent life is likely to be more advanced than us.

That's if all advanced civilizations don't ultimately destroy themselves with the technology they create. Which I personally believe is very possible. Which in turn would mean that older parts of galaxies are not necessarily more likely to have more advanced civilizations.

OK, now I see what you mean by "far too many assumptions to make" lol

For 200 years we hat letters and homing pigeons. Now we communicate with light or electric currents. What about in 500 years?
Advanced civilizations will have moved to something much better than light to communicate. Forget about picking up electromagnetic signals emanating from their planet, assuming that they still need to live on a planet or they have only colonized one.

Furthermore, an advanced civilization will probably not value us as individuals or as a form of culture. I mean, we consider dolphins, whales, chimps, horses, dogs and some other animals as fairly intelligent and look at how we treat them!
If an advanced society was indeed interested in finding intelligent life on Earth (because it seems like a good candidate because of all the oxygen in the atmosphere), it would define intelligence as something other than the ability to send radio waves or powerful lasers into space.

By the way, I once heard of a crackpot hypothesis by some guy who claimed that life on Earth was one of many scientific long-term experiments of a super advanced civilization. They seeded this planet with single-celled organisms and watched the evolution. At some point, for millions of years, all that they got was dinossaurs. Nothing interesting was going on, so they decided to send an object from the Kuiper or the Asteroid Belt to crash on our planet (to shake things up). After a few million years, some creatures with potencial arose (good ol' Homo Sapiens), and they come here periodically to collect specimens for lab tests (thus explainig UFO sightings and abductions). Sometimes they would intervene, somehow transmitting us specific knowledge and then watching how that new technical competences would evolve - which explains the glory of ancient societies such as the Mayans, the Egyptians, ancient Chinese, etc.

Now, this is absurd but not impossible. And if we actually found out about it, what a cold shower it would be... Remember that although we don't have the technology to do it yet, we are already thinking of ways to terraform planets, so in ten thousand years we could be conducting experiments like that. Maybe someone then starts connecting the dots.......

In conclusion, if we find intelligence on other planets, they could be more advanced than us, but not much more. The ones that are one million years ahead of us are not to see.

One more thing, we ASSUME that the path of a civilization through time is parallel to ours, so at some time they come to the brink of their self-destruction. If that is the case, soon after they drop the first atom bombs and irreversibly change climate, they also build permanent stations on their moon or on a neighbouring planet, so that if their home planet gets scorched, there are a few communities spread around that make it difficult for the whole civilization to perish.

For 200 years we hat letters and homing pigeons. Now we communicate with light or electric currents. What about in 500 years?
Advanced civilizations will have moved to something much better than light to communicate. Forget about picking up electromagnetic signals emanating from their planet, assuming that they still need to live on a planet or they have only colonized one.

It is assumed that any civilization goes through the same discoveries and progresses at some point in their history. No matter how advanced they are now, they would have had to use something more primitive before.

There are only so many types of signals we understand as a race, and therefore those are the only signals we can attempt to decipher. Anything more advanced than what we have would appear to us as indistinguishable or even unseen from out point of view. We certainly can't search for things which we don't even know exists! We must take things one step at a time.

Furthermore, an advanced civilization will probably not value us as individuals or as a form of culture. I mean, we consider dolphins, whales, chimps, horses, dogs and some other animals as fairly intelligent and look at how we treat them!

Which completely assumes that an advanced civilization would be as arrogant as we are youthful. It is entirely possible that as a civilization progresses or advances, they start to have more respect for other cultures and different levels of intelligence.

<snip> Now, this is absurd but not impossible. And if we actually found out about it, what a cold shower it would be...

That's just another God theory. Some alien beings wanted to perform experiment and "accidentally" gave us life. These more advanced beings then check in from time to time to see how we're doing, like any omnipotent or omniscient being would do to show some level of care (if not a personal love, then at least a care for their "objects", like a possession of sorts).

Fact is, theories like that one are always easy to cook up, because it's fun to imagine all the possibilities of our true origins. Until something like that can be verified by scientific fact, it's probably nothing more than someone's fervored imagination.

In conclusion, if we find intelligence on other planets, they could be more advanced than us, but not much more. The ones that are one million years ahead of us are not to see.

Very true. But the goal isn't to find the most advanced civilization. The goal is to simply find any civilization; to know we're not alone.

One more thing, we ASSUME that the path of a civilization through time is parallel to ours, so at some time they come to the brink of their self-destruction. If that is the case, soon after they drop the first atom bombs and irreversibly change climate, they also build permanent stations on their moon or on a neighbouring planet, so that if their home planet gets scorched, there are a few communities spread around that make it difficult for the whole civilization to perish.

You ASSUME that to be the case, but we have dropped our first atom bomb and yet we still haven't colonized our own moon, let alone another planet.

Inter-spacial colonizing may not be the result of any warring, but could instead be due to consuming resources at an alarming rate, thus needing to find new resources to consume. But that assumes they haven't found better ways than consuming their world's precious resources.

Again, far too many assumptions to make. The plain fact is we don't know anything about any of them, let alone if they even exist. We simply need to make that first step, which is simply to find them.

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It is assumed that any civilization goes through the same discoveries and progresses at some point in their history. No matter how advanced they are now, they would have had to use something more primitive before.

Yes, it is assumed. I can't imagine a completely different scientific progress. At some point they must have discovered atoms, molecules, aminoacids, radiation processes, pi, non-Euclidian geometries, etc. (not necessarily in this order...)

There are only so many types of signals we understand as a race, and therefore those are the only signals we can attempt to decipher. Anything more advanced than what we have would appear to us as indistinguishable or even unseen from out point of view. We certainly can't search for things which we don't even know exists! We must take things one step at a time.

Agreed. It's just that I find it annoying when I hear that by the time we find another civilization (assuming that we will...), it's going to be far more advanced than we are. Well, if so, we're not going to find them on 1400 MHz (give or take), unless they are deliberately sending us a message. Which is pointless to communicate, given the huge distances. It is more likely that they are more or less as advanced as we are, a civilization made up of individuals that think they're alone in the universe of have established contact with one or two other galactic companions and are searching for more.

Which completely assumes that an advanced civilization would be as arrogant as we are youthful. It is entirely possible that as a civilization progresses or advances, they start to have more respect for other cultures and different levels of intelligence.

Yes, that is entirely possible. But I'm thinking of aliens 1.000.000 years ahead of us, which is statistically possible. They will respect us but leave us alone. Who knows, maybe their definition of intelligence is to be able to cheat death... We don't qualify.

Very true. But the goal isn't to find the most advanced civilization. The goal is to simply find any civilization; to know we're not alone.

That is by itself remarkable. The next thing we're going to want to do is to get in touch. I don't know if it is in their nature, but it's certainly in ours.

There are only so many types of signals we understand as a race, and therefore those are the only signals we can attempt to decipher. Anything more advanced than what we have would appear to us as indistinguishable or even unseen from out point of view. We certainly can't search for things which we don't even know exists! We must take things one step at a time.

Agreed. It's just that I find it annoying when I hear that by the time we find another civilization (assuming that we will...), it's going to be far more advanced than we are. Well, if so, we're not going to find them on 1400 MHz (give or take), unless they are deliberately sending us a message. Which is pointless to communicate, given the huge distances. It is more likely that they are more or less as advanced as we are, a civilization made up of individuals that think they're alone in the universe of have established contact with one or two other galactic companions and are searching for more.

Very good point. While searching, we're searching for "primitive signals" coming from a comparatively primitive civilization, like ourselves.

But that assumes that a more advanced civilization wouldn't be purposely sending out a primitive signal for those like us. Lots of assumptions could be made from that too, such as their intent for attracting lesser civilizations.

Which completely assumes that an advanced civilization would be as arrogant as we are youthful. It is entirely possible that as a civilization progresses or advances, they start to have more respect for other cultures and different levels of intelligence.

Yes, that is entirely possible. But I'm thinking of aliens 1.000.000 years ahead of us, which is statistically possible. They will respect us but leave us alone. Who knows, maybe their definition of intelligence is to be able to cheat death... We don't qualify.

Maybe. I think death is part of any biological entity's natural cycle, but the length of time living may vary greatly depending on many factors.

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But what do we see here on Earth, 50 years ago, we widely used, gigantic (~50-1000MWatt) Radio & TV transmitters.
Today, with our problems about energy consumption & global heating, we more and more use a direct connection. See WWW, also Radio and TV-Broadcasting, telephone, videophone, etc., by cabel/fiber.

Here we (have to) use different kind of modulating/de-modulation signals.
But a more advanced civilisation, could have invented a different way of MO--/DEMO--Dulation technique.
L.A.S.E.R. is one of the later search-techniques, used to 'look' in another way.
But more and more we keep our signals close to us (Cabel/Fiber-Optics,etc.)
An exception, ofcoarse is RADAR and the use of satellites to 'broadcast'

IMO, the speed of light, (~300,000Km/sec), is the most difficult part. Therefore
we can't 'see', anything 'in real-time', unless it's nearby, f.i. our own solar-system. Or a 'nearby' constellation.
Meaning, 'information', picked up from a 1000 Ly (Light-Years), is 'old' and we only can predict if (we catch same sort of signals, from the same point), that
this 'source' (civilisation), either, still exists or has changed/advanced, changed their behavior about being (wanted to) detected or has expired.

According to our own physic-law's, anything reaching the speed of light, has
no mass and therefore can't exist. (Photons)

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May have missed it in the above but I recall a conjecture (might even have been the SETI folks themselves) that we may have a conundrum.

As we advance we discover much more efficient, lower energy ways to shuttle our communications around. Cell towers are now Earth bound and we don't bounce messages off satellites in orbit at nearly the same strength we once did in our more primitive days. Given the low wattage in cell communication as an example, it would never become a candidate for a civilization elsewhere hoping to pick up some of our chatter. If our days of broadcasting "I Love Lucy" into the cosmos are also over (cable networks and low energy satellite reception have now arisen in place of the ubiqutous rabbit ears television), we are a lot more quiet than we used to be.

In other words, our "noisey" period is coming to a close, hence the worry that perhaps the window of opportunity for catching another similar civilization out there is brief. In this scenario we could well see the radio telescope sweep right by ET's home and he doesn't seem to be making a peep. He is, but at such a low level locally that it's beyond our means to listen in.

Just another of the possiblities, but certainly not something to hang your hat on.

Regards,

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