Kepler team estimates 50 billion planets in Milky Way

[cosmicalstorm]

This is pretty awesome. I've been waiting for something like this, although I guess it's a very rough number.

How's this for an astronomical estimate? There are at least 50 billion exoplanets in our galaxy. What's more, astronomers estimate that 500 million of these alien worlds are probably sitting inside the habitable zones of their parent stars.

So how many of these exoplanets have life? Unfortunately, there's no estimate for that question.

SLIDE SHOW: Top 10 Places To Find Alien Life
DNEWS VIDEO: FINDING EXOPLANETS

This announcement was made on Saturday by Kepler science chief William Borucki at the American Association for the Advancement of Science in Washington D.C. However, Kepler didn't actually count 50 billion exoplanets, this number comes from extrapolations of the data taken so far by the exoplanet-hunting space telescope.

For example, as Kepler has spotted 1,235 exoplanet candidates so far -- 53 of which orbit stars in their habitable zones -- knowing approximately how many stars there are in our galaxy (there are thought to be around 300 billion stars in the Milky Way), an estimate can be made of how many worlds are orbiting these stars.

Kepler has only studied 1/400th of the sky, and it can only detect exoplanets that pass in front of (or "transit") their parent stars. Also, it needs more time to detect exoplanets that orbit further away from their stars.

Taking all these factors into account means that a lower estimate can be made. There's likely to be more than the 50 billion exoplanets Borucki describes.

Making this estimate is a relatively simple task, not so simple is estimating how many of these worlds might play host to life. As we know that only one planet in the Milky Way has life on it (Earth, in case you were wondering), no amount of statistical guesswork can arrive at an estimation for the number of alien beings that are out there.

Making estimates may sound trivial, but it does put the search for ET into perspective. There's at least 50 billion worlds, which have fostered the development of basic lifeforms? How many have allowed advanced civilizations to evolve?

If there are any space-faring alien races out there, "the next question is why haven't they visited us?" Borucki asked. He responded with: "I don't know."

http://news.discovery.com/space/milky-w ... orlds.html

[Edi]

That's an estimate based on so far discovered stuff, but given that there are more than 200 billion stars in this galaxy, it can safely be said that the estimate there is now a hard lower limit rather than anything else.

Our own solar system has 9 planets and a lot of smaller bodies like moons and so forth. Not all systems may have that many, but I expect many would have something at least. Many of the systems where planets have been discovered probably have more than one.

[Singular Intellect]

I have a sneaking suspicion many people still believe that any alien intelligent life we encounter will be akin to a Star Trek like scenario or other ideas portrayed in common fiction. Early industrial societies, bow & arrow primitives, maybe slightly advanced beyond us, etc.

Most likely we will only encounter extremely primitive life (bacteria) and/or life that has evolved for millions of years (like dinosaurs).

To speculate about encountering life having evolved to our level of technology and happening to encounter it within our time frame of development stretches credibility to extremely improbable levels.

The overwhleming likelyhood is either we'll encounter primitive life, or life so advanced beyond us that we better hope it has no manevolent intent towards us. If that were the case, a small group of spear weilding natives pitted against the sum of world's most advanced modern armies would seem a balanced match in comparison.

[Serafina]

The overwhleming likelyhood is either we'll encounter primitive life, or life so advanced beyond us that we better hope it has no manevolent intent towards us. If that were the case, a small group of spear weilding natives pitted against the sum of world's most advanced modern armies would seem a balanced match in comparison.

Or not - it all depends on how far technology will get us. We don't know the potential limits for material science, power production - and we don't know how complete our understanding of practicably applicable physics is. Perhaps we will hit hard limits in 200 or 1000 years - if that is the case, a race millions of years ahead of us would only have 200 or 1000 years on us technologically.
And even if megascale-projects, interstellar travel etc. were physically and technologically possible, they might take up too many resources and simply be so unworthwhile that no species intelligent enough to get to that point will ever do them

You are of ourse correct in your other aspects, i just wanted to point out that many people assume that our technology will progress for a long time without hitting hard limits. We know some limits, but we can not predict whether we will ever be able to find a way around them or not.

[ray245]

I won't even be surprised if we are the first intelligent life form that has ever evolved in the Milky way.

[Vehrec]

I would be-given the numbers game, and the age of the universe, it seems unlikely to me that we'd be the only sapient life. Then again, we're a once in four billion year occurrence, so who knows?

[Singular Intellect]

Or not - it all depends on how far technology will get us. We don't know the potential limits for material science, power production - and we don't know how complete our understanding of practicably applicable physics is. Perhaps we will hit hard limits in 200 or 1000 years - if that is the case, a race millions of years ahead of us would only have 200 or 1000 years on us technologically.

Even if we supposed only a minor edge over us technologically due to some hard limits, one cannot dismiss the sheer magnitude of industrial capacity a foreign civilization could muster against us.

One need look no further than WW2 to see how industrial might can overcome even superior design concepts. Germany's latest tanks outmatched an enemy tank five to one, and yet Germany still got steam rolled by the sheer numbers being brought against them.

And even if megascale-projects, interstellar travel etc. were physically and technologically possible, they might take up too many resources and simply be so unworthwhile that no species intelligent enough to get to that point will ever do them

If one examines our own development of nano, computer and bio engineering and the very realistic (some even say conservative) potentials of such technology, it seems quite absurd to think that any more advanced civilization wouldn't have that technology as well and effectively be able to cheaply manufacture absurdly large numbers of advanced technologies and capabilities.

Given a few hundred thousand (or millions) years of industrial growth, normal exponential growth patterns would end up having us facing a potential enemy that would consider deploying a force outnumbering us billions to one as having no particularily significant impact on their industrial capacity.

You are of ourse correct in your other aspects, i just wanted to point out that many people assume that our technology will progress for a long time without hitting hard limits. We know some limits, but we can not predict whether we will ever be able to find a way around them or not.

As I stated above, even a technologically inferior enemy can steam roll a more advanced one with sheer industrial capacity.

Given what we currently know about physics and the universe, we're still a long ways away from having hit the roof on any particular technology.

I won't even be surprised if we are the first intelligent life form that has ever evolved in the Milky way.

Or the universe for all we know. After all, presumeably there has to be a first one at some point, there's no reason to dismiss the possibility that may very well be us.

There's no universal calendar that would suggest we're 'early', 'late' or 'on time' for intelligent life existing at any point in our universe.

[Formless]

If you are going to talk about the entire universe so casually, then you have to remember that there are billions of other galaxies out there besides our own. Even if there is only civilization one per galaxy, that's more intelligent life than can be counted.

But this entire conversation is all speculation and probability anyway. Especially if you want to talk about future industrial capacity and technological development.

[Serafina]

Even if we supposed only a minor edge over us technologically due to some hard limits, one cannot dismiss the sheer magnitude of industrial capacity a foreign civilization could muster against us.

Yes. Which is why is was talking about technology.

Given a few hundred thousand (or millions) years of industrial growth, normal exponential growth patterns would end up having us facing a potential enemy that would consider deploying a force outnumbering us billions to one as having no particularily significant impact on their industrial capacity.

The "facing" part is where the problem kicks in: We simply do not know if interstellar travel is a serious (or even theoretical) possibility. It might be that the best that's possible by the laws of physics is sending simple probes.
As for "mega-scale projects", sure, an advanced civilisation could certainly use most of the resources in their solar system. But when i said "mega-scale" project then i meant something like Dyson-spheres/swarms/whatever or other things we could see over interstellar distances.

The prospect might not be amazing, but it is quite possible that our universe is just restricted to very much sub-light (not even high relativistic) travel, and that none of the stuff we see in sci-fi will ever be possible. A million-years old technological civilisation could just consist of an AI-ruled, fusion-powered conglomerate of space stations which have been built from using up that systems asteroids. Their only contact with other solar systems would be probes that will never reach us because there are billions of systems, and radio-waves that will never reach us because they get swallowed by background-noises. They did not chose to civilise any other solar systems simply because it would take too much resources, or because it is not feasible to send living beings or even AIs over interstellar distances. If they did, they would have picked a couple of neighboring star systems - they would have sent AI-ships on a ballisitc course, which would mine asteroids at their target location and take millenia to build up. At best that would give them a very slow spread-rate - they would hop to a new solar system every couple of millenia.

There is actually good evidence for this: We do not see any evidence for true interstellar civilisations. We have not discovered any mega-scale projects. We are pretty certain that FTL-travel is impossible. We do not disvocer any signs of large interstellar civilisations, even if they would not interact with us.
That must mean one of a couple of things:
-We are the first and therefore only technological civilisation in our galaxy.
-Civilisations wipe themselves out or run out of resources before they become noticable on an interstellar scale.
-Making an impact on the interstellar scale is either impossible or not worth it.
-Technological advance is really tweaked and technological civilisations end up in virtual realities, become "energy beings" (or somesuch) or something else which makes them unnoticable to us.

But this entire conversation is all speculation and probability anyway. Especially if you want to talk about future industrial capacity and technological development.

Quite. All i want to say here is that it is simply quite possible that technology simply can not advance to a point where it affects anything over interstellar distances, or is even noticable over them.

[Singular Intellect]

If you are going to talk about the entire universe so casually, then you have to remember that there are billions of other galaxies out there besides our own. Even if there is only civilization one per galaxy, that's more intelligent life than can be counted.

Quite true, but given space time can expand faster than the speed of light itself (and IIRC is what is happening), unless we assume FTL capabilities on part of our galactic neighbors, encountering them becomes a rather moot point.

But this entire conversation is all speculation and probability anyway. Especially if you want to talk about future industrial capacity and technological development.

Except in that case we have a working model to base such speculation on, namely us.

[Formless]

Quite true, but given space time can expand faster than the speed of light itself (and IIRC is what is happening), unless we assume FTL capabilities on part of our galactic neighbors, encountering them becomes a rather moot point.

Do you have a source for this? Yes, at the edge of our Hubble radius the universe is expanding too fast for light to ever reach us. But that's a result of the distance involved, not of spacetime expanding locally faster than light. But then I'm no cosmologist (and neither are you).

Except in that case we have a working model to base such speculation on, namely us.

A sample size of one is too small to be used in a statistical argument. ANY statistical argument. You should know better. If, for example, life comes about more often on worlds with higher than earth gravity (and I have heard reasons that might be true, namely that such planets will stay warm for longer and have stronger magnetic shielding) then spaceflight becomes even harder to achieve, and that model becomes worthless.

[Singular Intellect]

Do you have a source for this? Yes, at the edge of our Hubble radius the universe is expanding too fast for light to ever reach us. But that's a result of the distance involved, not of spacetime expanding locally faster than light. But then I'm no cosmologist (and neither are you).

Unless I'm swimming in ignorance, space/time would have to be expanding faster than light, otherwise light would inevitably cross it, with the only net effect being it took longer to transverse an increasing distance.

Someone here more knowledgeable can correct me if I'm interpreting the concept incorrectly.

Except in that case we have a working model to base such speculation on, namely us.

A sample size of one is too small to be used in a statistical argument. ANY statistical argument. You should know better. If, for example, life comes about more often on worlds with higher than earth gravity (and I have heard reasons that might be true, namely that such planets will stay warm for longer and have stronger magnetic shielding) then spaceflight becomes even harder to achieve, and that model becomes worthless.

My comment there was referring to accelerating industrial capacity and technological developments, not distribution of life forms across the cosmos or the conditions imposed upon them from their local enviroment. Obviously different planets and systems present different challenges and could easily shift development times for certain feats one way or the other.

But there's no reason to assume other forms of life can avoid exponential trends of expansion and development as it occurs with us, unless you submit a zero percent growth rate or exponentially increasing doubling time (linear growth) for some reason.

Which is a bit nuts honestly, because that would imply no matter how big the population is or vast the technological field is, it doesn't produce more than a fixed figure increase/fixed rate of progress. Which is like claiming a breeding population of a few thousand or few billion always adds the same figure of twenty new people annually to the sum total, as if the inital sum has no bearing on the calculation.

[starslayer]

Do you have a source for this? Yes, at the edge of our Hubble radius the universe is expanding too fast for light to ever reach us.

This is not true. At the Hubble radius, yes the recession velocity is the speed of light, but we can still see galaxies there, and even far beyond it. the Hubble radius is c/H0, where H0 is the Hubble constant; at present, the radius is about 13.8 billion light years in comoving coordinates (this is how astronomical distances are usually given in magazines and such). However, we can see objects that are 40-50 Gly away. The reason for this is that the Hubble radius increases with time, so light that was initially emitted when it's recession velocity was greater than c can move into a region where this is not true, as the Hubble radius increases and "catches up" with that light.

But that's a result of the distance involved, not of spacetime expanding locally faster than light. But then I'm no cosmologist (and neither are you).

I'm a little fuzzy on this, but I think this is pretty much true (my GR class did not touch on this much). Locally, spacetime is not currently expanding faster than light anywhere, although there is no prohibition on it doing so. Globally, the effect adds up.

[Formless]

To starslayer: Thank you for the correction. Much appreciated.

My comment there was referring to accelerating industrial capacity and technological developments, not distribution of life forms across the cosmos or the conditions imposed upon them from their local enviroment. Obviously different planets and systems present different challenges and could easily shift development times for certain feats one way or the other.

So? The question of whether or not we should see evidence of ET civilizations is inherently based on assumptions about the distribution of those civilizations that are capable of getting into space. Besides, exponential growth ain't worth a hill of beans if your environment prohibits the development of key gateway technologies. See below for more details.

But there's no reason to assume other forms of life can avoid exponential trends of expansion and development as it occurs with us, unless you submit a zero percent growth rate or exponentially increasing doubling time (linear growth) for some reason.

Which is a bit nuts honestly, because that would imply no matter how big the population is or vast the technological field is, it doesn't produce more than a fixed figure increase/fixed rate of progress. Which is like claiming a breeding population of a few thousand or few billion always adds the same figure of twenty new people annually to the sum total, as if the inital sum has no bearing on the calculation.

Did you actually try and think about how a different gravity rating would effect things? Besides making it harder to get into space (which would explain why we don't see lots of flying saucers, one of the major questions at stake here) it also dissuades large scale terrestrial civil engineering projects of the kind that improves quality of life and thus enables greater specialization of labor needed to make technological progress in the first place. Its not just space colonization, though that's arguably one of the biggest gateway technologies there is.

And that's just gravity mucking up your predictors. Biology, evolution, ecology, and geology make it even harder to generalize from our own civilization. A species that evolved more like ants or bees, with castes of slave workers hardwired into their biology, would have no incentive to create labor minimizing technology no matter how intelligent they were or dedicated to science they are. A sentient species that appeared relatively early in their planet's history of life might not have easy access to fossil fuels, and thus no easy way to industrialize. A species that lacks the widespread distribution of humanity, say because they were not as nomadic as we were, might not know to gather their planet's resources together at all. If they never had the luck to stumble on a suitable food crop they won't develop agriculture. A planet with a different atmospheric composition, say one with heavy particulates and appropriate distance from their sun, will not necessarily have things like radio or astronomy because their atmosphere renders it pointless. A waterbound sapient species obviously will not develop the way we did. A species that simply did not have lots of surface minerals will not have high technology either. And so on and so forth. Simply having some technology doesn't ensure your technological growth will be exponential. You have to have the right technology, environment, and worldview. THEN you might get that kind of growth/development.

Edit: I should note that while all my examples are ones that hinder development of technology, you can also speculate ones that do the reverse. Its possible that we got dealt a less than stellar hand, but all the other civilizations in the Milky Way got even shittier ones.

[tim31]

Most likely we will only encounter extremely primitive life (bacteria) and/or life that has evolved for millions of years (like dinosaurs).

...and the problem with a statement like that is that there us those of us living in hope of a planet of the dinosaurs. There's always going to be disappointment

[Guardsman Bass]

I should note that while all my examples are ones that hinder development of technology, you can also speculate ones that do the reverse. Its possible that we got dealt a less than stellar hand, but all the other civilizations in the Milky Way got even shittier ones.

I'm honestly not sure what they would be - most of them would simply be more of something. I suppose a civilization with a greater tendency towards forming settled communities that grow crops might develop specialization of labor earlier on, but that's no guarantee of more advanced technology. It's much easier to speculate on what might inhibit a civilization than what might enhance it.

The "hive insect" scenario is interesting. I suppose you could have them do a high-technology-but-labor-intensive path, where they develop technology that complements their readily available supply of labor (instead of taking a path that relies on increasing automation and labor-saving technology), but it's difficult to speculate on how something like that might happen.

Back to the OP, I'd be curious to see more information about those 53 planets in the habitable zones of their stars. This earlier article talks about what we know so far about the planets they found. There's a very large number of Neptune-equivalent planets, about 200 multi-planet systems, and so forth.

[Zaune]

There is actually good evidence for this: We do not see any evidence for true interstellar civilisations. We have not discovered any mega-scale projects. We are pretty certain that FTL-travel is impossible. We do not disvocer any signs of large interstellar civilisations, even if they would not interact with us.
That must mean one of a couple of things:
-We are the first and therefore only technological civilisation in our galaxy.
-Civilisations wipe themselves out or run out of resources before they become noticable on an interstellar scale.
-Making an impact on the interstellar scale is either impossible or not worth it.
-Technological advance is really tweaked and technological civilisations end up in virtual realities, become "energy beings" (or somesuch) or something else which makes them unnoticable to us.

That said, not only is our space-telescope technology just barely reaching the point where we can reliably identify extrasolar planets smaller than a gas giant, but we don't know with real certainty what the signs of an interstellar civilisation are. We have a whole range of educated guesses, but all of them are based on predictions of technological developments that are supposedly decades or centuries away when we struggle to guess what the state of the art will look like in another fifteen years.

[Zac Naloen]

Using all of what we know now, has anyone plugged into the Drake equation, is the answer much different to the initial estimates?

[JME2]

So, 50 billion estimated planets, eh?

Plenty of chow for Galactus, then.