Earth-like exoplanets may be common, study says.

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Jim1348

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Message 2016524 - Posted: 25 Oct 2019, 1:02:44 UTC

Seth Shostak, a senior astronomer for the SETI Institute in Mountain View, California, echoed Scharf’s assessment of the new research. “It’s a very ingenious scheme to learn if worlds like Mercury, Earth or Mars are common or otherwise,” he said in an email. “Fortunately for those hoping to find life elsewhere in the cosmos, it seems such planets are likely to be ubiquitous.”

https://www.nbcnews.com/mach/science/earth-planets-may-be-common-cosmos-study-says-ncna1070161

I don't think there are very many studies that are particularly relevant to SETI, but this seems to be one of them.
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Message 2016529 - Posted: 25 Oct 2019, 1:51:01 UTC - in response to Message 2016524.  

What are the requirements for Earth-like plants to exist and start and evolve intelligent life. I can think of perhaps a dozen parameters that are in a narrow range for this to be the case. How many have we found that meet even one or two of these requirements ??

Anyone who claims they are ubiquitous in our Galaxy is most likely a faker. I claim that they are sparsely distributed if they exist at all.
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Message 2016542 - Posted: 25 Oct 2019, 4:59:56 UTC - in response to Message 2016529.  

I claim that they are sparsely distributed if they exist at all.

Give a percentage for "sparsely."
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Message 2016587 - Posted: 25 Oct 2019, 13:34:41 UTC - in response to Message 2016542.  
Last modified: 25 Oct 2019, 14:25:04 UTC

Give a percentage for "sparsely."


I ,at one time, ran my own version of the Drake equation idea but with 12 parameters that I assumed were essential and each about 20% likely--some were more likely such as what % of stars were non-binary spectral class G or red dwarves that were at least 4 billion years old etc. I seem to remember coming up with single digit numbers --maybe 5 or so to perhaps as many as 1000 in the galaxy that met all 12 requirements for intelligent life to form and evolve. I then did some sloppy solid geometry and opined that they were perhaps as far as 30,000 light years apart. This was for intelligent civilizations to be time and space co-temporaneous so that we might receive a message from a powerful beacon before we all died. I avoided the 0% that we might get from our current 4000 planet catalog--realizing that it is currently difficult to analyze planets with existing methods and platforms.

Of course our current inventory of known planets and moons does not meet even the most basic two or three requirements but we will improve our catalog as time goes by. I agree that most if not all stars have planets and many have moons--but, I also posit that a number of unlikely events formed our solar system and our Earth-Moon arrangement and that these events were quite extraordinary in their probability.

So for sure, I have no right to be smug in my estimates or quoted in learned journals--however I claim the right to as much uncertainty as even the best pundits and Saganesque showmen. I would love to be proven wrong when we decode those messages from Proxima Centauri !!

So I humbly propose a ranking system for any planet candidate. If they are in the temperate zone they get a 1, if also in a near circular orbit they get a 2. if their gravity is in a narrow range they get a 3--water they get a 4 and so on.
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Message 2016591 - Posted: 25 Oct 2019, 15:26:15 UTC - in response to Message 2016587.  

I don't think we are at all likely to find intelligent life with our current generation of radio telescopes. I expect it will take a couple of orders of magnitude increase in sensitivity, meaning at least the Square Kilometer Array (if they ever get that built), or large arrays in space or on the moon.

But as Richard Haselgrove points out, using the Breakthrough telescope in a targeted search is a lot better than the previous searches.
https://setiathome.berkeley.edu/forum_thread.php?id=84788&postid=2016578
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Message 2016599 - Posted: 25 Oct 2019, 16:31:48 UTC - in response to Message 2016524.  

Seth Shostak, a senior astronomer for the SETI Institute in Mountain View, California, echoed Scharf’s assessment of the new research. “It’s a very ingenious scheme to learn if worlds like Mercury, Earth or Mars are common or otherwise,” he said in an email. “Fortunately for those hoping to find life elsewhere in the cosmos, it seems such planets are likely to be ubiquitous.”

https://www.nbcnews.com/mach/science/earth-planets-may-be-common-cosmos-study-says-ncna1070161

I don't think there are very many studies that are particularly relevant to SETI, but this seems to be one of them.

Thanks for sharing, Jim! I share Dr. Shostak's reaction to this study. It seems a quite ingenious way to establish that basically Earth-like planets are relatively common. This would, of course, improve the odds of a SETI detection. It seems that every time we learn something new, bearing on the number of habitable planets, it's encouraging news for SETI.
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Message 2016608 - Posted: 25 Oct 2019, 17:52:17 UTC - in response to Message 2016599.  

That was my reaction too. It is ingenious. How else can you determine the composition of exoplanets? You can barely detect they are there at all.
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Message 2016613 - Posted: 25 Oct 2019, 18:51:11 UTC

I suspect a lot of this error bars comes from our insistence that life be like ourselves. We haven't even really begun to search our own solar system for life. Looks like Mars has some interesting places to look. We have a couple of moon of the gas giants that look promising. Time to find out just how much extreme conditions can be and life arise. If it is able to thrive in much bigger goldilocks zone, then the chances of intelligence get higher too. I'm pretty confident life is near ubiquitous. Length of intelligent civilization with interstellar communications capability may be short. Which means ETI may be all over, just not at the same time.
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Message 2016614 - Posted: 25 Oct 2019, 19:24:14 UTC - in response to Message 2016613.  

I'm pretty confident life is near ubiquitous. Length of intelligent civilization with interstellar communications capability may be short. Which means ETI may be all over, just not at the same time.

That is the kicker. They need to survive long enough to send us signals, and we need to survive long enough (as an advanced society) to receive them.
It is a long time until the next Ice Age bails us out.
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Message 2016671 - Posted: 26 Oct 2019, 2:12:10 UTC
Last modified: 26 Oct 2019, 2:13:55 UTC

Spreading through the galaxy, even at sub-light speeds, should make intelligent life ubiquitous, in any case. It would also tend to lengthen the lifetime of any given civilization in space. A supernova, or an asteroid collision could wipe out a civilization in only one solar system, but not if they were widely-enough distributed.

Expanding territory is not some peculiarly human trait. It exists is most forms of life on this planet, where conditions permit it. It is a strongly life- enhancing evolutionary trait. It seems entirely reasonable that this should be the case, wherever life exists.
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Message 2016679 - Posted: 26 Oct 2019, 4:27:29 UTC

It is still my opinion that, as of now, speculation about intelligent life in the universe is just that, speculation. It is hard to conceive that in all of the universe ours is the only planet to have fostered intelligent beings. But, at least for now, there is no proof that, at this time, there are any other civilizations within range of our ability to detect.
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Message 2016718 - Posted: 26 Oct 2019, 14:16:19 UTC - in response to Message 2016671.  
Last modified: 26 Oct 2019, 14:16:36 UTC

Spreading through the galaxy, even at sub-light speeds, should make intelligent life ubiquitous, in any case.


Your reasoning is based on the assumption that leaving one's solar system and surviving to start again elsewhere is possible. Maybe that's the limiting factor, and there's intelligent life is all over the galaxy... but they're all stuck in the gravity well of their planet and star, just like us. Energy and resources requirements to travel between stars may simply be impossible to fulfil.

Expanding territory is not some peculiarly human trait. It exists is most forms of life on this planet, where conditions permit it.


Emphasis is mine: most life we know on Earth is adapted to rather specific conditions. Space travel and whatever planets orbit the nearest stars may simply not permit the long-term survival of would-be colonists.
Gazing at the skies, hoping for contact... Unlikely, but it would be such a fantastic opportunity to learn.

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Message 2016725 - Posted: 26 Oct 2019, 14:53:59 UTC - in response to Message 2016718.  

We know that intelligent life on Earth evolved from earlier forms here, from the fossil record. And it appears that simple life can probably arise whenever the conditions are right, which seems to include a fairly wide variation (as long as water is around). So I see no reason for the travel notion, though it appeals to some people.

The real question is simply one of statistics. Intelligent life here (the only one we know about) had to jump through a long and tortuous history of evolutionary hoops. How often does it happen? Certainly not elsewhere in our solar system, or even most solar systems. Apparently one requirement here was a large moon to stabilize our orbit, and that appears rare. There are dozens, if not hundreds, of other criteria, not to mention timing of catastrophes. They have to be often (and big) enough to wipe out previous species, but not the next ones.

So here we are. The more relevant question for us is how long will our species be around?
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Message 2016729 - Posted: 26 Oct 2019, 15:33:13 UTC - in response to Message 2016725.  

Yes, Earth life benefited from the Moon's stabilisation effect (as well as other factors such as the planet's magnetic shield). That still leaves rocky moons orbiting gas giants as interesting candidates for complex life.

Regarding intelligence itself, it evolved independently in different species on Earth: crows and dolphins are proof of it, possibly octopuses too though they're hard to assess. Intelligent life seems to arise pretty easily from complex (multicellular) life. The remaining question is how likely is bacteria-like life to evolve into more complex and organised structures?

Humanity may still survive for quite some time; it doesn't mean our ability to reach even near Earth orbit will. Come back in a few millions of years when lots of oil have had time to form again and Earth intelligent life, whatever form it'll have taken by then, has another shot at space exploration.
Gazing at the skies, hoping for contact... Unlikely, but it would be such a fantastic opportunity to learn.

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Message 2016736 - Posted: 26 Oct 2019, 16:16:46 UTC - in response to Message 2016729.  

Regarding intelligence itself, it evolved independently in different species on Earth: crows and dolphins are proof of it, possibly octopuses too though they're hard to assess. Intelligent life seems to arise pretty easily from complex (multicellular) life.

Just because you can come up with a definition of "intelligence" that can include crows and dolphins does not mean that it is very useful.
I define "intelligence" as the ability to construct instruments that can see to the visible edge of the universe. The octopus don't make it.
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Message 2016750 - Posted: 26 Oct 2019, 19:26:15 UTC

Intelligent life, life stupid enough to build radio.
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Message 2016751 - Posted: 26 Oct 2019, 19:29:27 UTC - in response to Message 2016736.  

"For instance, on the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much—the wheel, New York, wars and so on—whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man—for precisely the same reasons."
--- Douglas Adams, The Hitchhiker's Guide to the Galaxy
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Message 2016763 - Posted: 26 Oct 2019, 21:34:20 UTC - in response to Message 2016613.  

A thought provoking discussion of the Fermi paradox is in this paper from 2018. https://arxiv.org/abs/1806.02404
It suggests that we could be the only detectable species in the universe (using our current technology). Obviously, I hope that's not the case.
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Message 2017112 - Posted: 29 Oct 2019, 12:06:30 UTC - in response to Message 2016524.  
Last modified: 29 Oct 2019, 12:08:11 UTC

It’s a very ingenious scheme to........


It might be ingenious to verify that rocky material exists in space. However it is a disingenuous scheme to suggest that this means that Earth-like planets are ubiquitous and therefore intelligent life (such as ours) is rife throughout the Galaxy.

Rocky planet may be only one of a dozen requirements for a planet to be dubbed TRULY Earth-like
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Message 2017972 - Posted: 6 Nov 2019, 10:32:34 UTC - in response to Message 2016529.  

What seems true is there are alot more planets than we ever imagined existed.

20 years ago we knew of only 9.

Today we know that most stars have planets.

Most estimates put the number of stars in our galaxy at 100 -300 billion.

That means hundreds of billions of planets in the Milky Way.

There are anywhere from 200 billion to 2 trillion galaxies in the observable universe.

That would make for a mind-jarring large number of planets out there.

Now, we know the answer to Drake's equation variable of how many planets go on to evolve intelligent life to be at least 1, which is us.

We also know that physics and chemistry is the same throughout the observable universe.

To say that what happened here (Earth), which is a rather ordinary part of the universe, is not likely to have happened elsewhere seems highly unlikely.

So the chance that there is intelligent life -- lots of intelligent life -- out there is probable.
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