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Comment by jmiserez | Hacker News Reader

FYI: The title sounds like clickbait, but is actually explained in the article. As technology improves further in the next few years, we’ll be able to scan so many more stars simultaneously that a possible discovery would be have to be made (if they exist).

Overall an interesting article by Seth Shostak of the SETI Institute.

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I fail to see any reason behind proclaiming 2035 as the deadline within the article. The author could have very well said 2030 or 2040 and it would have been the same article.

> Within two decades, SETI experiments will be able to complete a reconnaissance of 1 million star systems, which is hundreds of times more than have been carefully examined so far. SETI practitioners from Frank Drake to Carl Sagan have estimated that the galaxy currently houses somewhere between 10,000 and a few million broadcasting societies. If these estimates are right, then examining 1 million star systems could well lead to a discovery.

I think he's basing the date on the assumption that we'll have searched 1 million star systems by 2037 and there are a few million broadcasting societies.

Personally I think the odds are pretty damn long, even on the optimistic end of Sagan's and Drake's assumptions. Assuming there are 200-400 billion star systems in our galaxy, that gives us a 1 in 200-400k odds of finding one by 2037? I'll take the bet.

Still a great read, I'm much more fascinated by the idea of artifacts. I believe that the longer we go without finding things, the more seriously we should be thinking about leaving things.

would need to be a few million broadcasting societies, broadcasting in a way we can detect.

and there could be aliens in other galaxies! we wouldn't detect them by 2035

article was pretty nonsense imho

On the optimistic end of Sagan's range, there are "a few million" broadcasting societies, call it 2 million. If there are 400 billion stars, that means that there's one broadcasting society per 20,000 stars. If they're evenly distributed, and we sample 1M stars, then our odds of missing with all 1M samples are negligible (about 1/10^22).

(I don't think that there are a few million broadcasting societies in our galaxy. But if there are, we'd expect to find them soon.)

I have trouble believing there's more than a handful of spacefaring species per galaxy. Even without FTL travel, one species could fill up all of the habitable planets in a galaxy the size of ours in a few million years or less, thanks to the fact that we breed exponentially. And there's been Sun-like stars for a while now in our galaxy, presumably with Earth-like planets orbiting them. So it's a matter of getting there first.

If there are a "handful," then there are probably 0 (besides us). You have to believe that there's a very narrow range of values to get precisely to a handful.

Like, the range quoted above is from "10,000 to a few million," so a factor of 200ish from high to low range.

If you think that there are 10, per galaxy, why don't you believe instead that there are 0.3 per galaxy (only off by a factor of 30?)? How much confidence can you have in your highly speculative variables that your output can be constrained down to just a single order of magnitude or so?

By handful I mean < 5. Probably usually just one. Because no others would get a chance to evolve, with all the habitable planets quickly being occupied by whichever species figures out interstellar travel first.

I think you have a very Golden-Era-of-Sci-Fi space-opera conquering view of spacefaring.

Why do we need to expand? Our population growth is already levelling off.

Why do we need to send _our bodies_ rather than with AI, or with our consciouses uploaded into computers? (a la Charles Stross' Accelerando or Greg Egan's Diaspora)

If we're sending AI probes around, why do we need to take all resources to the extent that we prevent other species from developing?

Most of the fundamental science that we want to do can be done right here in our own solar system. There's just not a need to expand.

Once you have sufficiently advanced technology, unless you also have some kind of totalitarianism, it only takes a few groups of people who disagree about the allocation of resources (or, really, anything else) in this star system and want to leave. And then the same thing happens recursively in whatever star systems they go to, and you have exponential growth until it saturates to cubic or whatever.

Yes, of course, they will be AIs or uploads or body printers. Even for an advanced civilization, shipping bags of meat to other star systems would be wasteful. That doesn't mean they won't want to use resources, or that there would be no evidence of them if they were already here.

edit: There's certainly scenarios in which the first species to explore a galaxy doesn't literally prevent other species from evolving. But that doesn't mean they wouldn't be obviously detectable. The likely number of starfaring species in the galaxy given our observations is zero.

> There's just not a need to expand.

It doesn't take a need, just a desire. Someone wanting to be able to say, "I went there. I saw it. I got the T-Shirt."

They don't need to be spacefaring, just broadcasting. Of course if there are 10,000+ aliens advanced enough to broadcast radio and laser, we do have to wonder why this hasn't led to the galaxy being filled up over the past 5 billion years. Drake's answer to this is that space travel is too expensive, cramped and lengthy to be worth it.

A couple of assumptions here. The first is that our solar system has habital planets from their perspective, I wouldn't completely rule out that there chemistry could be very different to ours. The second is that they need habitable planets. The idea of living in under ground tunnels isn't palatable to us because we evolved in wide open savanahs, an underground, underwater or nocturnal species might not feel the same.

I wonder if there are intelligent species that are incapable of developing spaceflight due to environmental reasons. For example, an intelligent water-breathing species on a planet that is quite a bit more massive than Earth.

A ship filled with water has a lot more mass than a ship filled with air. That extra mass compared to what we face, combined with starting from a high gravity world, would mean they would need significantly better propulsion systems than we need to get to orbit.

Could this mean that chemical based rockets would not be sufficient for them to do manned spaceflight? If so, they may never establish a manned orbital presence, and a manned orbital presence may be necessary as a stepping stone to interstellar travel.

discounts great filters

Agreed on it not being clickbait, although I wish he went into more detail about how Sagan et al came up with their estimates, since that seems to be key to his whole argument.

https://en.wikipedia.org/wiki/Drake_equation

The Drake equation along with the Fermi Paradox are well known in conjunction with SETI's goal for the past several decades. Seth, Frank Drake, Carl Sagan and Jill Tarter have all publicly talked about their justification for being confident in SETI's eventual success. Sagan even wrote a science fiction book about it that was made into a movie.

I've never understood claims like this. For all we know, the universe could be infinite. Yes, that would mean the universe contains an infinite amount of energy and that we'd find dopplegangers of ourselves if we travel far enough, but we can't be sure it's not true. We can't even be more or less confident in one hypothesis vs another.

Articles like this would be more persuasive if they had qualifiers like "Within our observable universe."

A lot of people don't realize just how much bigger the universe might be than "the observable universe".

I thought it had been established that the universe, as a (hyper)volume of spacetime is finite?

That doesn't mean infinity isn't lurking somewhere beyond though.

Maybe in theory but I don't think that's something that could be empirically verified. An axiomatic theory is rather a working assumption, because anything else is mathematically intractable. How could anyone understand something that's too big to understand?

My impression is that Multiverse Theories are a fad playing on semantics.

The size of the universe is irrelevant to SETI, since they're just trying to detect alien civilizations in our neighborwood, which would mean the Milky Way.

> For all we know, the universe could be infinite

if an infinite number of trees fall and and nobody is there to hear it, do they make a sound?

Maybe not clickbait, but he sure buried the lede. Thanks for the TL;DR. Wasn't clear what his point was from a quick skim.

Sounds great, but there is slim chance of finding them, and even if we do, they will be too far away. We should instead prepare to meet the artificial intelligences of tomorrow, which are a sure bet. It will be like Lee Sedol trying to understand AlphaGo, not like the linguist professor from the movie Arrival trying to understand Alien language.

> possible discovery would be have to be made (if they exist).

...and if they want to be found.

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