Active SETI.

[ZedNova]

I don't really care, by the time any alien race gets ANYTHING that we've broadcasted, we'll be either extinct or sufficiently advanced to detect them as they launch their massive "invasion" ships. Assuming they even care about the short garbled signals, or can reach us in decent time.

It's possible that hundreds of space faring species have already died out, it's possible that many species just decided: "Space is too hard, lets play with these other things we've made instead". It's also possible that we're the only species in the universe that has created anything like our definition of "Civilization"( I hope this isn't the case, but it very well may be).

Although life is almost certainly out there, it either needs to be really close by, or we need to be totally wrong about the speed of light barrier for us to ever see it.

[architeuthis]

I recall reading on Centauri Dreams an essay suggesting we would need a 50 sq km phased array antenna to make sense of our own civilization's radio signals if they were hypothetically broadcast from Proxima Centauri only 4.4 ly away. This is a simple ramification of the inverse square law of radiation. It implies that our current SETI is based on the faith that other civilizations either use very high energy broadcasts, or are trying to actively signal us themselves. The silence of the galaxy is troubling. One explanation is that we are the first in our galaxy, however this seems improbable.

There is too little information to accurately gauge the risk of broadcasting for all to hear our location to the galaxy. Inferences made about E.T. civilizations based on our own history and psychology is bound to be loaded with indefensible cultural assumptions, not to mention the mother of all sampling biases.

So we may have everything to gain... or maybe we have everything to lose. IMO it is foolish to make existential bets when you don't know what the odds are.

[PakledHostage]

What if there is a very advanced civilisation in some 20 light years away from the Sun - but their culture evolved differently to ours? Instead of building technological society their advancement was concentrated on philosophy, art and "soft" sciences?

2) Culture A wants something from us or our world that they can't get at home.

So I guess we're in trouble if Scotius' space hipsters want our PBR?

[xcorps]

Our species is terrifyingly good at mass murdering ourselves without using nuclear ordnance.

Compared to what?

Reminds me of a Twilight Zone episode Small Talent for War.

[magnemoe]

More to the point, technologically superior cultures destroy technologically primitive cultures if the following things happen:

1) The technologically superior culture (which we will refer to as Culture A henceforth) goes out and finds the technologically primitive culture (which we will refer to as Culture first.

2) Culture A wants something from Culture B or from the land on which Culture B lives which Culture A, for some reason, cannot get at home.

3) Culture A is disdainful of other cultures and doesn't mind mocking, altering, or even wiping out Culture B, and

4) Culture B is sufficiently rigid that it cannot reliably absorb shocks to its system.

So let's look at these items in order, as applied to Active SETI. Keep in mind that we humans will be playing the role of Culture B.

1) Culture A comes to Sol and finds us first. This implies that we aren't looking for other cultures - actively or passively. We stay at home and keep quiet for fear of attracting strangers. This policy of isolation puts the initiative in contact firmly in the hands/claws/tentacles/whatevers of Culture A, leaving us entirely at their whims. This can also occur if Culture A was to show up in orbit tomorrow, while we're still debating this issue.

2) Culture A wants something from us or our world that they can't get at home. This is a point I find very hard to accept, given that, as we learn more and more about planets outside our solar system, it is clear that most raw materials that exist in our solar system also exist in others. Anything they need to mine, farm, harvest, or manufacture, they can do so at home. If they have so depleted themselves that they need to mine other systems for resources, they will have likely depleted themselves to the point where they cannot travel to meet us, much less exploit us. We could, I suppose, imagine resources or things Culture A may desire from us, but that is speculation on top of speculation, and gets us nowhere.

3) Culture A is disdainful of other cultures and doesn't mind mocking, altering, or even wiping us out. This is the one point we can never know until contact has occurred. We can speculate all we want about how cruel or kind an alien culture may be, but until contact is initiated, it will remain speculation. I suspect even the aliens of Culture A may not know how they will deal with other cultures until they initiate contact.

4) Culture B - us - is sufficiently rigid that it cannot reliably absorb shocks to its system. This is the one item we can control, and that's by maintaining efforts to explore the universe and search for other cultures, both passively and actively. If we give up that search and turn inward, I predict we will, as a species, become less receptive to the concept of contact, and less resilient to the changes that will necessarily follow. Thus, when contact finally occurs, it will be more likely to break us - even if Culture A acts very carefully not to do so.

Conversely, an Active SETI policy can do the following things:

1) It puts the initiative of contact in our hands. Rather than wait for the hypothetical Culture A to find us, we start the conversation, and put Culture A in the position of having to decide if and how to reply.

2) It puts the concept of contact foremost in our minds, and a priority that must be tended to in our agendas. After all, if a suitably powerful beacon is built, sooner or later we will get a reply, either by radio or by ship. It would only be responsible of us to make sure we are ready for that eventuality.

3) It tells Culture A that we're serious about - and ready for - contact. Referring to the "Smart SETI" article I mentioned in my last post, the Benfords figured that a beacon capable of reaching out to 600 light years would probably need a cost of 4 billion dollars to run (Figure 1, page 36), and that is the minimum cost. That's about the cost of an aircraft carrier - or 1/4 of NASA's current budget, IIRC. Beacons detectable across greater distances will cost more. While Culture A will not be able to know our budget constraints, I expect they will be able to do the math on the resources needed to build a beacon, and realize how much we have committed to the effort. The more distant Culture A is from us, the longer the concept of contact will have been at work in our minds, and the greater the chance that we will have prepared for contingencies. Culture A will likely realize this once our beacon is detected, the distance (and hence time since the beacon was first activated) it lies from them, and so will know that, if they choose to initiate contact, they will have to tread carefully, lest they mess things up.

Of course, we do face risk if we send a beacon, but I submit the risk is greater if we stay silent - if they contact us, we will be reacting, not acting. And those who react always react at a disadvantage.

Good analyze, 3) fit well with my joke story above, and yes it would had worked out better had they known about humans before leaving. however they left before radios was invented anyway.

As for 2) earth has an oxygen atmosphere and a advanced ecosystem, it also has humans who will making resupply far easier than having to build all infrastructure from scratch.

However for someone who can do star travel its pretty trivial to find that Earth has an oxygen atmosphere. It would make it an interesting target anyway.

Main argument against active SETI is that we don't know who planets having life but we will find out with better telescopes and it would be better use of money to focus on this as it will give results. Active Seti will not give an response within a budget period

[Seret]

They'll be too far away for us to send a message back in a timely manner, so we can't even be pen pals.

Pen pals is likely all we could be. Nothing at interstellar distances can be done in "a timely manner". That's just the way it is. If it ever happens it'll be a long, slow conversation that takes place over many generations. That may not be how Hollywood wants it, but it's how the laws of physics insist on it being.

[78stonewobble]

Hmm...

It has been estimated that:

That there is between 100-400 billion stars in the milky way.

That there is atleast 1 planet per star.

That 1 in 5 sun-like stars have an earth size.

Assuming 200 billion stars that means 11 billion habitable earths, which rises to 40 billion if red dwarf stars are included.

Freefloating planets in the milkyway possibly number in the trillions.

Yes, we have sometimes relocated and disenfranchised people to get to ressources, but it seems to me there are, on a galactic scale, PLENTY of ressources to go around.

Going to earth and wiping us out / enslaving us, seems to be a giant waste of time, energy and possibly manpower when you could instead go to a "free" system.

If interstellar travel is insanely ressource intensive I'd wager you don't want to waste anything on carrying too many weapons or soldiers, if you can avoid it. Which means ignore earth, which is taken and take another place.

If interstellar travel is rather cheap, there's no reason to go to earth either, there will be plenty of planets within reach. A simple pacifist way of neutralising us as well, by outgrowing us, or just denying us access to close by habitable planets.

I think it would be much more advantageous for aliens to trade with us, give us the tech to mine the solar system and just drop in and buy stuff up.

Not that I think interstellar travel is gonna be cheap or easy anytime soon, if ever.

Personally I think it will allways be so hard and ressource intensive, that most civilisations will sit on their planet untill random comet/asteroid/supernova wipes them out and only a few of them will ever manage spread to only a few more systems.

[Javster]

Look we've been a technological society for say 300 years, which doesn't even register, cosmically speaking. Any one we meet out there will be vastly beyond our level of development, possibly by billions of years.

Active SETI is not science, but an attempt to provoke a reaction from an alien society whose abilities and motives are unknown to us- a reaction that will have serious consequences for all of humanity.

It is not wise to shout into the jungle.

With that amount of tech, they could probably obliterate us from where they are, if they wanted to. Maybe they know we exist but they're hiding.

[Sky_walker]

Hiding? More like: We're too primitive to find them.

(Notice that the further civilization develops - the less EM emissions it wastes by radiating it into space).

[Duxwing]

I second this, there's little to be gained by starting an east v west discussion.

Oops! I had worried I'd erred.

-Duxwing

[Exclipse]

If technology throughout the universe never plateaus then trying to stay quiet while developing our own technology makes no sense because any other beings out there who are ahead will always be ahead. So whether we notify other beings about our existence with radio signals or by warping into one of their star systems makes no difference.

If they exist at a higher tech than us and have an interest in our destruction then it will happen sooner or later anyways.