What kind of signal would have to be received to consider SETI to be a success?

Question

An explicit message? Or just something regular and mathematically interpretable?

The hot hydrogen section of the radio spectrum, the so-called "watering hole" approach, is a pretty smart angle, but what if hypothetical aliens were using gravity waves for signaling, or a neutrino stream, or something else that we don't have the tech to interpret right now?

Could someone be sending an explicit "Hello there" right now and we're just not "listening" in the right way?

Answer 1

We'd be extremely happy with a narrow band radio signal that originates in space, where multiple observatories can detect it over space and time.  We're nowhere near the stage of decoding it.

Answer 2

Can you hear me now??

just kidding.  

Yes, anything with a definable pattern.  There are far too many frequencies and that is why they have elnisted our help.  

http://setiathome.ssl.berkeley.edu/

This is the link to where YOU can be a part of it all.  It is fun.

Answer 3

Like in the book/movie Contact, Prime Numbers would be a very strong indicator of an intelligence.

Answer 4

We're not looking for a "hello there" message specifically, we are looking for any signs of electromagnetic anomalies of artificial origin.

Just as many science fiction authors have speculated that alien civilizations could pick up earth's TV and Radio signals, we're basically looking for the same thing.

It is doubtful that aliens are trying to send us a deliberate message when the message would take years to reach us under the best circumstances, if it could reach us at all.  Imagine writing a letter to a pen pall and waiting a few years for a response, then your response takes a few years... it doesn't make much sense.

As technology advances, we may come up with new and better ways to find these artificial signals, or the development of a Grand Unification Theory may help us think of new ways to find these signals.

For the time being, we're just looking for something that is not the result of a naturally occurring phenomenon... thats all.

Answer 5

A couple issues to consider.

If they are sending a "hello there" message now, assuming they are using the electromagnetic spectrum as it's "mode of transport" we will not receive it until it can cover the distance required.  (i.e. a 100 light year distant planet communication would not reach us, if sent at this precise moment, until 2108).  This would mean that they would (most likely) need to be relatively on the same technological advancement as us.  And we would need to be listening to and for the right frequencies.  

It's completely possible alien civilizations sent messages in our direction, but it passed us during the 1300's, and there was no one here capable of receiving it, let alone determine whether it was of intelligent design.  What if such a civilization has found more efficient ways of communicating blindly into the cosmos, and have abandoned radio signals?  Maybe they are less advanced, and we are sending messages to civilizations that are in the equivalent of "the middle ages?"

I think the project is worthwhile, but at the same time, it does seem as futile as trying to find a single needle in one of at least 100,000,000,000 haystacks, and there's still no garuntee that the needle exists.

Answer 6

We're using what we have to listen to the stars. And we have a better chance of finding something that way than by not doing it at all.

Answer 7

Any extraterrestrial societies still using radio communications would most likely be doing what we are doing, just listening to back ground transmissions and hoping to get lucky and pick up a strong signal from another solar system, i suppose they would use mathematics to communicate, maybe some form of binary code.