B Will we ever communicate with extraterrestial life in a reasonable time frame?

[mfb]

Catanzar1 et al. ApJ 738 151 (2011)

Online
That's based on the first four months of Kepler data, it's only looking at Sun-like stars, and only considering "Earth analog" planets. Kepler had no chance to observe three transits for habitable planets around Sun-like stars in that time so there is a huge amount of extrapolation involved as well.

Edit: Wikipedia's article explicitly references this as "older study" for historic context, it has a much larger more recent estimate in the previous paragraph.

But this won't make any difference - if I shrink the habitable zone, the fraction of habitable planets goes up, but the number of candidates goes down by the same factor.

It does make a difference because the references count planets in the habitable zone, not some much larger area. Venus-like planets and moons are not included in the numbers for planets in the habitable zone, so you shouldn't include them in your comparison either.

However, I question the entire premise of your post. I reported this as speculation untethered by science, and the Mentors elected to keep this thread going. Fine. Your call. But you can't then turn around and complain my speculations don't match your speculations.

There are published numbers and reliable estimates we can discuss.

 

[sbrothy]

Well, when you looked it up on Wikipedia, you would have discovered there are 130 K, G and F type stars within 50 light years. You also, when you looked it up on Wikipedia, learned that estimates from Kepler are that 1.4-2.7% of such stars have planets in their habitable zones. That's 2-3, one of which is the sun.

So, there are 1 or 2 candidate stars. To have a civilization, this requires that the star not only has planets in the habitable zone, but that these planets are habitable. The sun has, arguably four: Venus, the Earth, the Moon, and Mars. Only one is habitable.

The rest is speculation, but I point out:

• For half of earth's history, there were no eukaryotes
• For 75% of eukaryote history, there were no multicelluar organisms
• For 99.5% of multicelluar life history, there were no people (genus homo)
• For 99.5% of human (genus homo again) existence, there was no civilization.
• For 99% of civilization, radios did not exist.

Give all that, 1 or 2 candidate stars does not seem like a lot.

It comes back to Arthur C. Clarke's argument about Apes or Angles..

 

[Vanadium 50]

I didn't read it. Lots of extraneous stuff on that link, and when he says the Earth will last a (US) trillion more years, he's using outdated information. How outdated? Could it be "jungles of Venus" outdated? Maybe, maybe not.

There is certainly a lot we don't know, such as how long technological civilizations last. We do know that the scientific method could have taken root in at least four cultures, but did not.

I suspect - but certainly do not know - that energetics plays an important role. That's not good for intelligent life, because K class stars are far more common than G and F's and the brighter the star, the shorter its life. It may well be that dim stars never get going, and bright stars usually don't last long enough. Or not. How would you know?

 

[hutchphd]

@sbrothy : Did you really mean "Angles"? I'm just a midwestern boy.....but.....that sounds wrong to me.

 

[sbrothy]

Yup. Follow the link and press pgdwn once. In my opinion he makes a compelling argument.

 

[gmax137]

Angels, not Angles.

 

[sbrothy]

Oh.. OH! HAHA. whoops. yeh. my bad. English is my second language.
"Apes and 90 degree angles." :P

 

[BWV]

It comes back to Arthur C. Clarke's argument about Apes or Angles..

Which comes back to the Fermi Paradox - if ‘angels’ ever evolved somewhere in the galaxy and developed the tech and willingness for interstellar travel - even with drones at say 0.1C - then where are they? Galaxy is old enough to have been completely colonized by self-replicating von Neumann probes

 

[256bits]

early 18th century metallurgy.

I will also add, Do all these exoplanets have the similar geologic history as the earth with minerals on the surface ready and available for exploitation by the intelligent.

 

[sophiecentaur]

Consider the probability of peace on Earth And we're all pretty similar and with the same aims.

Little green men are very unlikely and friendly ones even less so.

 

[symbolipoint]

Consider the probability of peace on Earth And we're all pretty similar and with the same aims.

Little green men are very unlikely and friendly ones even less so.

By chance maybe some very few of them could be friendly, especially if they feel so inclined as to stop for food at a place called, Eats. He may even offer one of his cigarettes.

(reference to Cub Koda, and Martian Boogie)
(simply trying to supply a little fun thoughts again)

 

[sbrothy]

Consider the probability of peace on Earth And we're all pretty similar and with the same aims.

Little green men are very unlikely and friendly ones even less so.

Any organism which has managed to set itself up as the apex predator of it's planet is bound to be a nasty piece of work. There is, after all, only so many ways to be a shark (or in this extended metaphor: an Orca Whale).

 

[phinds]

There is, after all, only so many ways to be a shark (or in this extended metaphor: an Orca Whale).

Or a human. Lots of us have good intentions but we as a species didn't get to the top of the food chain by being nice and we today are the descendants of those of our forebears who got to the top of OUR food chain in addition to that of all other species. It would be nice to think we have overcome that but ... not all of us have.

 

[sbrothy]

Or a human. Lots of us have good intentions but we as a species didn't get to the top of the food chain by being nice and we today are the descendants of those of our forebears who got to the top of OUR food chain in addition to that of all other species. It would be nice to think we have overcome that but ... not all of us have.

Also, I don't think we should. Being peaceful and in harmony and having beaten our weapons into plowshares may well be admirable. Until we're visited by the Evil Empire of Rigel who demands or water and women.

 

[phinds]

Until we're visited by the Evil Empire of Rigel who demands or water and women.

And our booze. Don't forget our booze. I'm not putting up with any race that tries to take our booze, by gum !

 

[pinball1970]

Assuming they are hostile if they are out there is the smart thing to do. Clearly they are doing the same by keeping quiet.

 

[sbrothy]

As I understand it we're entering a time where radio and TV is beamed by satellite from space onto the earth (hard as it is to imagine nothing slipping by and entering space anyway) as opposed to the way we started out: sending everything out in all directions. Think Sagan's book "Contact" (and film) where the first message we receive from ET is one of our very own we send out: Hitler's incredibly tasteful speech to his - well yeh, minions, and their enthusiastic Nazi-salute response. I'm sure even a somewhat slow alien civilization would be a little alarmed by that. Especially knowing that that was a long long time ago, and no matter how many episodes of "I Dream of Jeanie", "Dark Skies" "X-Files", "Big Bang Theory", not to mention actual serious news on SALT-talks and the Cuba Crisis came later the smart thing to do was keeping your options open.

I think hiding is not the first thing any species think of before it's too late.I mean:

"Ooohh look radio waves! Bzzzz. hmmm... wait....."

 

[Vanadium 50]

Until we're visited by the Evil Empire of Rigel who demands or water

There was an 80's TV show with this premise - reptilian aliens wanting to steal our water. It starred a young Jane Badler in a tight top, which kind of spoiled the premise: she is unquestionably a mammal. Unquestionably.

 

[Vanadium 50]

I am not sure it makes any sense at all to talk about alien intentions in human form, other than to say that anything you want to steal or conquer at the end of a quadrillion mile supply chain is not worth the trouble.

As far as watching Hitler, TV is probably hopeless. Modulation is not trivial or obvious. AM Radio is more likely, as it is more straightforward, higher power, and in some cases has only one station per frequency. The clearest signal, though is radar - our Little Green Men looking for asteroids that might crash into their planet.

Related - Aricebo has a gain of a whopping 73 decibels. That's a factor of 20 million. But by the cold heart of the inverse square law, that's a factor 4500 in distance - if your radar is good to the orbit of Saturn, you can detect it one star over. Want to go 10x farther? You need 100x the (effective radiated) power.

 

[gmax137]

I am not sure it makes any sense at all to talk about alien intentions in human form,

Right. They are not "just people" from another planet. Ponder how alien an alien could be. Different moral structures, different emotions, different reproductive mechanisms, and on and on. They could be toadstools with a sense of humor. Communication depends on shared experiences and we might not share any with beings from other worlds.

...other than to say that anything you want to steal or conquer at the end of a quadrillion mile supply chain is not worth the trouble.

Right again. This is why you can't write a space opera without a cheap effective "jump drive" of some magical sort. The distances involved are mind boggling, as hard to grasp as the number of molecules in a glass of water. You can write down the numbers (50 million light years! 10^23 molecules!) but we, with 10 fingers, have no intuition about what these numbers mean.

 

[sophiecentaur]

AM Radio is more likely

I'd have to disagree there. AM is such an inefficient mode that any species that had only got that far would be of no interest to us and wouldn't be capable of useful comms. We would need to be looking for a signal with very much noise-like characteristics which would carry (amongst other signals) a low data rate 'signature' signal. This signature could be dragged out of a very noisy signal - barely managing to squeeze itself down the antenna feed - and contain information (in comms speak) about how and when to find the meat of their message.

 

[sbrothy]

There was an 80's TV show with this premise - reptilian aliens wanting to steal our water. It starred a young Jane Badler in a tight top, which kind of spoiled the premise: she is unquestionably a mammal. Unquestionably.

You're talking about The 1984 V series I presume.

I've never actually watched it. There even seems to be a 2009 remake. I don't know if the premise is the same.

The water-stealing always struck me as patently ridiculous but we all know that water is a very very limited resource in our universe *cough*.

But of course there miay be more to it than that as I haven't really looked into (or indeed onto) it.

 

[sbrothy]

I am not sure it makes any sense at all to talk about alien intentions in human form, [...]

TV-Tropes: Blue-and-Orange Morality.

 

[sophiecentaur]

water is a very very limited resource in our universe *cough*.

Lol. Two very common elements which react well together. tumteetum.

There's a lot of it in the Oort cloud and the aliens would pass through it on their way to Earth. Oh, and yes - they would have their own Oort cloud around their own star.

 

[PeroK]

There was an 80's TV show with this premise - reptilian aliens wanting to steal our water. It starred a young Jane Badler in a tight top, which kind of spoiled the premise: she is unquestionably a mammal. Unquestionably.

Interstellar travel being technologically more practical than manufacturing water, of course!

 

[sophiecentaur]

more practical than manufacturing water

or even interplanetary,
Thing is that Earth was absolutely bone dry to start with (as was Mars). We both accreted lots of water (comets) but Mars mostly lost it. We think of water as being 'special' to us (blue planet etc,) but it's all over the place. Often much easier to extract than to 'make' or go shopping to another star.
Desalination is achieved by many sea birds and 'lizard people' look as though they could do it as a matter of course. (Is that racist?)

 

[sbrothy]

Lol. Two very common elements which react well together. tumteetum.

There's a lot of it in the Oort cloud and the aliens would pass through it on their way to Earth. Oh, and yes - they would have their own Oort cloud around their own star.

Yes. Let's not talk about hydrogen. One of the rarest elements since the dawn of the universe. :)

 

[BWV]

Outliving your home star appears to me the only economic argument for interstellar travel. A technological civilization capable of expanding to another star system would possess a strong incentive to ensure the survival of their species (assuming they placed a value on that). However, that leads back to the Fermi
Paradox - so where are they?

 

[sophiecentaur]

Outliving your home star appears to me the only economic argument for interstellar travel. A technological civilization capable of expanding to another star system would possess a strong incentive to ensure the survival of their species (assuming they placed a value on that). However, that leads back to the Fermi
Paradox - so where are they?

'Outliving your home star' involves timescales of many hundreds of millions of years. What Earth organisms have had that sort of lifetime and also had high tech? Humans, after just a few hundred years of tech, have been on the brink of self destruction for some while. We'll be hell and gone long before the dear old Sun undergoes any significant changes.

Where would the 'strong incentive' come from? How desperate would the situation need to be before the 'strong incentive' for personal gain and survival would be replaced by an altruistic incentive to propagate the species elsewhere? You assume that tech ability correlates with social maturity. Do you have any evidence to justify this assumption?

The SciFi model is based on a totally Earth based situation of 'go west young man'; take Zane Grey themes and put them in space ships. In the days of colonisation, places that were colonised by westerners had already been occupied by other earlier peoples. Sci Fi is no more real than Fantasy Fiction as so many posts on PF demonstrate. That's fine as long as we avoid planning a future that's based on SciFi.

 

[BWV]

'Outliving your home star' involves timescales of many hundreds of millions of years. What Earth organisms have had that sort of lifetime and also had high tech? Humans, after just a few hundred years of tech, have been on the brink of self destruction for some while. We'll be hell and gone long before the dear old Sun undergoes any significant changes.

Where would the 'strong incentive' come from? How desperate would the situation need to be before the 'strong incentive' for personal gain and survival would be replaced by an altruistic incentive to propagate the species elsewhere? You assume that tech ability correlates with social maturity. Do you have any evidence to justify this assumption?

The SciFi model is based on a totally Earth based situation of 'go west young man'; take Zane Grey themes and put them in space ships. In the days of colonisation, places that were colonised by westerners had already been occupied by other earlier peoples. Sci Fi is no more real than Fantasy Fiction as so many posts on PF demonstrate. That's fine as long as we avoid planning a future that's based on SciFi.

did you read my post? The point was IF a civilization developed the capability of interstellar travel and IF they placed a value on the survival of their species THEN an incentive would exist to expand outside their solar system