Seti

[Moontanman]

SETI puts a considerable effort into finding extraterestrails under the assumption that they want to be found and are intentionally putting out a enough radiation in some way for us to detect them. Recent upgrades allow them to detect relatively nearby extraterestrails by eavesdropping on their normal communications.

But what if the extraterestrails do not want to be detected? It has been hypothesized that extraterestrails might want to smack down any up and coming civilizations to prevent competition. This might cause them to want hide or to simply not wanting to be bothered by primitives.

If we assume that extraterestrails are really hiding then how could we detect them? What would we look for to detect ET's if they are not actively broadcasting or if they are actually hiding?

[Buffy]

Nothing strange about this topic Michael! Moved to Anthropology because....

...think about it: what if you replaced the word "extraterestrails" with say, "African Pygmies" or "Big Feets"?

Why would you want to hide? In another thread around here, one motivation (ours) would be to avoid being noticed by Borg-like "civilizations".

No wonder those Pygmies hide....

To get a man's attention, just stand in front of the TV and don't move. He'll talk to you. I promise,
Buffy

[Moontanman]

Originally Posted by Buffy

Nothing strange about this topic Michael! Moved to Anthropology because....

...think about it: what if you replaced the word "extraterestrails" with say, "African Pygmies" or "Big Feets"?

Why would you want to hide? In another thread around here, one motivation (ours) would be to avoid being noticed by Borg-like "civilizations".

No wonder those Pygmies hide....

To get a man's attention, just stand in front of the TV and don't move. He'll talk to you. I promise,
Buffy

it would seem to make sense for primitives to hide instead of look for the big guys. Of course to all depends on how easy star travel really is, and what a civilization a thousand or a millions years ahead of us could do or would want to do. From the stand point o find sight wouldn't the native Americans have wanted to hide from the Europeans?

Contrary to modern belief the native American weren't all that inferior to The Europeans. If not for the small pox and religious fear the Americans could have kicked the Europeans back into the ocean easily. Of course hind sight is always 20/20 If the Europeans had waited another couple hundred years it might have been the native Americans who visited them instead of the other way around.

If ET's hide from each other due to concerns like interstellar conquorers or simply not wanting to be influenced by superior beings then how do we find them? I think one idea was that a really advanced civilization would enclose their entire star and would be detectable as a source of infrared radiation instead of a star.

[Buffy]

If you watch enough Star Trek episodes, I think it becomes clear that beings hide from both the higher and lesser "others," albeit for different reasons. I think ST also shows that there's always someone higher up on the "intelligence/power" scale!

Very good, Captain. There is hope for you. Perhaps in several thousand years,
your people and mine shall meet to reach an agreement. You are still half-savage, but there is hope. We will contact you when we are ready,
Buffy

[Moontanman]

Originally Posted by Buffy

If you watch enough Star Trek episodes, I think it becomes clear that beings hide from both the higher and lesser "others," albeit for different reasons. I think ST also shows that there's always someone higher up on the "intelligence/power" scale!

Very good, Captain. There is hope for you. Perhaps in several thousand years,
your people and mine shall meet to reach an agreement. You are still half-savage, but there is hope. We will contact you when we are ready,
Buffy

Since it's obvious we cannot hide, yet, and no one seriously wants to hide anyway these days. How do we go about finding them? A civilization that uses energy will always show some sort of signature. We leak radio waves into space and have been doing so significantly for at least 75 years. So what do we look for if they aren't trying to signal their presence and they are trying to hide?

[Eclogite]

Shortly we shall have the capability to carry out spectroscopic analysis of terrestrial planets around other stars. Monitor the atmospheric composition of these planets to identify changes analagous to the anthropogenic changes in the Earth's atmosphere.

Search for EM signatures associated with interstellar star drives.

If you wan't to remain hidden you probably want to know what others are doing. therefore conduct a search of the solar system for robotic alien monitoring systems.

[Moontanman]

[quote]

Originally Posted by Eclogite

Shortly we shall have the capability to carry out spectroscopic analysis of terrestrial planets around other stars. Monitor the atmospheric composition of these planets to identify changes analagous to the anthropogenic changes in the Earth's atmosphere.

This might show a civilization comparable to ours but a really advanced civilization could and probably would stop and reverse all the changes we have made like pollution. I would like to think an advanced culture has disposed of planets completely but this would be speculation.

Search for EM signatures associated with interstellar star drives.

Wouldn't we have to know what an interstellar drive was first?

If you wan't to remain hidden you probably want to know what others are doing. therefore conduct a search of the solar system for robotic alien monitoring systems.

I really like this one a lot but short of going out and physically inspecting every body in the solar system how would we detect them?

[lemit]

I have a question about SETI.

From what I've heard, it seems the search might be fairly restrictive in its verifying patterns. I have got an impression they have been listening for a very basic pattern of a single frequency that is repeated for hours at a time.

If my impression is correct, wouldn't that basic, simple, repeated pattern be more indicative of a natural phenomenon? Wouldn't sophisticated communication be more varied? Are we really interested in finding the most boring life in the universe?

I hope my impression is wrong.

--lemit

[CraigD]

Originally Posted by lemit

From what I've heard, it seems the search might be fairly restrictive in its verifying patterns. I have got an impression they have been listening for a very basic pattern of a single frequency that is repeated for hours at a time.

SETI assumes that some – not necessarily all or many, but at least a few – ET civilizations want to be discovered by listeners like us, so purposefully make an effort to make it easy for us.

An obvious way to do this is to send a strong signal at a frequency where natural sources are weak. On such range of frequencies is about 1420 MHz to 1640 MHz, known as the “water hole” because it falls between the emission line of unexcited hydrogen and OH. It’s not the only “quiet band”, but an easy one for radiotelescopes to monitor, so SETI focuses most of its listening on frequencies in this band.

Originally Posted by lemit

If my impression is correct, wouldn't that basic, simple, repeated pattern be more indicative of a natural phenomenon?

SETI doesn’t look only for repetition of changes in amplitude at a given frequency – an initial indication EM radiation isn’t naturally generated noise – but for the amplitudes to be mostly of two values, indicating binary data, and also that the signal originates from a single location.

Once such a signal is found, again assuming it was sent with the intention that we be able to read it without too much, SETI looks for sequences such as counting, lists of the primes in order, and similar data that would be almost certain evidence of an artificial, intelligent source. A signal consisting of a number of bits that’s the sum of two or three prime numbers is another strong indication of an artificial signal, and additionally that the signal is a 2 or 3-D pixilated image with dimensions of its prime factors.

SETI occasionally sends signals of the same kind it’s looking for. The 1974 “Arecibo message” is a famous example. It’s 73*23=1679 bits long.

Originally Posted by lemit

Wouldn't sophisticated communication be more varied?

Yes. Since sending EM signals over long distances is energetically costly, everyday “real” communication is likely to be both directional and compressed. Compressed data appears nearly random, and would be difficult to distinguish from noise.

Again, SETI assumes that we’d be receiving a signal intentionally created to allow us to detect and decode it, not overhearing everyday communication.

[lemit]

Thanks, Craig.

That makes a lot more sense than what I thought I had heard. Thanks for the information.

--lemit