Why does the SETI Institute (Search for Extra Terrestrials) assume the radio signals aliens might send are anything like what we call radio signals?

IT DOESN’T TO ME EITHER :D:D:D:D
I’m glad someone’s finally brought this up.
I’d love to see a UV detector, like different shades. Filter out the known stars and see what else is giving off light.
Or as stupid as it sounds a smell-o-scope (yes… futurama) but it’s not that stupid really. I mean like you said, their signals might be completely different.

The chances of us finding anything via sound is just stupendously low. Not to mention the fact we have to scan all of space in our tiny little microscopic frame of time. And then even if we did find something and it was say 3 million light years away, then anything we’re detecting now happened 3 million years ago!

although having said that I love SETI since they’re the only group REALLY trying… GOOOOO SETI!

Radio waves have the ability to pass through insulators, which makes them the most likely segment of the electromagnetic spectrum to reach us over astronomical distances. If an intelligence were to look for a way to communicate over light years, radio would be the likely choice.

It’s my understanding that SETI is simply looking for any non-random pattern in the radio spectrum. Space is full of random radio noise, but the assumption is that any communication would have to have a non-random nature to stand out from that noise.

By saing non-random, I presume you mean something sinusoidal-like?

@Harp, but radio would be the most likely choice of the things MAN is familiar with, no? Why would they assume ET would have the same choices?

@Mr_M: If it’s all we have to go on why nitpick?

radio is a simple method of signal transmission; essentially its a binary code, transmitted via carrier waves. If an ET civilization has the technology to advance into deep space, its assumed that they would have mastered radio long, long ago. It may not be their customary method of communication, but it would be available as one of their many means of establising a link to an unknown civilization.
Also, if they were to examine our technology, they would realize that we aren’t as advanced as they, and thus would have to ‘stoop’ to our level and develop this archaic means of telecommunication (if they didn’t have it already); a small step backwards if you will.
I do appreciate however, your insight that alien technology cannot be presumed to model after our own.
I myself tend to flucuate between a belief that there is intelligent life indigenous to other planets, or not. As of today, I tend to doubt it, or even if there was, the universe being so immense, its unlikely we would meet within millenia.

Why are we spending money on this? Don’t answer; the though just boogles my mind.

A signal intended for communiction over those distance would have to have at least two properties: it would have to travel fast, and it would need to be hard to stop. Since we’re pretty sure that the physical speed limit of the universe is the propagation speed of electro-magnetic radiation, then there wouldn’t be a faster way of spanning that (necessarily huge) distance. EM radiation in the sub-radio wavelengths is easily stopped by insulators, which makes it a bad candidate.

If a communication is intended for a civilization of unknown technical sophistication, then it would be logical to use a means that doesn’t require a highly advance detection system. The technology for detecting radio waves is not highly sophisticated, so it could be assumed that any technically savvy culture would soon develop those means.

What we call “radio” encompasses an enormous chunk of the EM spectrum. I’m not sure how broad a band SETI listens to.

From here, which is a sort of flaky looking site but their reasoning for radio use seems sound:

“Why use radio?

“Radio signals travel throughout most of our Milky Way galaxy with very little interference. They even pass through thick clouds of dust that prevent us from seeing many stars. Most scientists who have looked into the problem of communicating between stars believe that radio is the easiest and cheapest way to search. Some think that light waves are better, and there have been a few searches looking for light signals—optical SETI, or OSETI programs. But most SETI projects have looked for radio signals.

“Wouldn’t an extraterrestrial civilization use something far more advanced than radio with which to communicate?

“It’s entirely possible that there is some unknown method of communicating, and that radio may seem as primitive to aliens as smoke signals do to most of us today. However, we can only use the technology we know. Even if a more advanced method of intergalactic communication exists, an extraterrestrial civilization might choose to use radio because it is the most primitive method able to communicate across the galaxy, perhaps increasing their chances of contacting other civilizations.”

And, if you want something a little less flaky and more scientific-looking, here you go.

@laureth , nice link. And your analogy to smoke signals is right on.

@asmonet, I don’t really understand what you mean.

@TheKNYHT, I believe there is other life out there, however, I have NO problem believing there might NOT be. And I feel that the odds of finding life are highest on the planets closest to a planet that HAS life, i.e., earth. And if it isn’t there, it may not be anywhere.

Laureth summed it up, it’s basic, we know it works and there are enough arguments that make sense for it to be worth the effort in my opinion.

Why would a planets proximity to ours make it more likely to have life? That’s a bit solar system centric. As far as I know, that’s a silly assumption. If anything I would expect it to be farther away. Excluding of course Europa and things in our solar system that have a high likelihood.

@asmonet, just from a biology perspective alone. Let’s say you were able to find bacteria on a specific spot (say, on a rotting mouse for instance). The most bacteria would be at the specific spot, with some of the same bacteria at points immediately surrounding the spot. Then less and less the farther away you go from the spot.

If some “cosmic force” split the earth beneath the spot in 2 distinct pieces (or three or ten), the pieces nearest the spot have the greatest odds of also having the bacteria. If that bacteria evolved into man on the “spot”, then the odds are best that other men would develop on the pieces nearest “the spot”. IMHO.

But that doesn’t work, after the big bang everything split up, as far as we know it wasn’t a giant spot of bacteria that split up after that – life developed much later. Conditions arose that supported life, it’s probable that those same conditions would develop elsewhere, not necessarily close to us. Your example just doesn’t fit with current theories. Now, there is the theory that life arrived on the planet from an asteroid or something, but still, it would have traveled a long way, and it wasn’t from our solar system most likely.