# 11 billion earths



## JoanDrake (Nov 7, 2013)

Galaxy may have 11 billion Earth-like planets - SFGate

11 to 40 billion yields 1100 to 4000 planets having life developed to our level if we use the worst likely values (1%) of the Drake Equation

Which yields 11 to 40 if we add another parameter for having real time interstellar flight capabilities

More than enough that we may run into them one day, but not enough that we should be asking "where are they?"

And note that when we add red dwarfs, that is red suns, the numbers go up a good bit

Welcome, Kal-El. 

I was disappointed to find that Kepler is no longer working. I hope we can get the Russians to repair it as we seem to have no manned space flights planned


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## Bowler1 (Nov 7, 2013)

I've copied your link into writing resources and creating imaginery worlds where the question on how many possible alien worlds could be out there gets asked all the time. I've just made it 17% of all stars could have life on earth like planets - that's like WOW!

Ok, there are 300 billion stars out there, such a small number.
Possibly, 11 billion suns with earth like planets, see link above.
Thats 3.66% red dwarf stars systems with the right conditions for life.

Ok, there are 300 billion stars out there, such a small number.
Possibly, 40 billion red dwarf suns with earth like planets, see link above.
Thats 13.33% of stars systems could be just like ours.

Or a total of 17% of star systems could have earth like planets with the right conditions for life.


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## Vertigo (Nov 7, 2013)

To be fair I suspect those figures are a bit skewed. They state that the stats are based on planets roughly the same size as Earth, in the goldilocks zone in orbits around similar stars to our own. What they don't mention is how many of those are close to the centre of the galaxy and so bombarded by so much radiation that life (or at least complex life) is highly unlikely (not even cockroaches could take that kind of radiation). And of course close to the centre is where the vast majority of stars are in the Milky Way.


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## Bowler1 (Nov 7, 2013)

I'm not going to let facts get in the way of a good statistic, Vertigo mate.

3% Of systems with possible planets we could turn up at and call home will do for me.


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## J Riff (Nov 14, 2013)

Oh finally... the aliens are real huh? S'about time. )


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## Bowler1 (Nov 14, 2013)

Of course I'm real, and I've been here for ages and ages!


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## Harpo (Feb 27, 2014)

over 700 new exoplanets found in one day!
Yahoo News UK & Ireland - Latest World News & UK News Headlines


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## ralphkern (Mar 30, 2014)

Also consider it's a function of time as well as space. As far as we're aware, in four billion years Earth has only cultivated one species with the potential for interstellar travel. I remember an old adage that if the age of the Earth was converted to an hour then humanity would only exist for a second. 

I still think the Fermi paradox holds true as a single race with interstellar caperbility should be able to colonise the galaxy in a relatively short time period (by that in at least 50000 years assuming they can get to light speed) There's simply no verifiable evidence. Once a race goes interstellar it should be 'future proof' (barring truly catastrophic events like gamma ray pulsars) and the continuing expansion of that races terratory. 

All it would take was one of those species gestation to have occurred a 'couple of minutes' before us and they should be everywhere.


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## Natimus15 (Mar 31, 2014)

ralphkern said:


> Also consider it's a function of time as well as space. As far as we're aware, in four billion years Earth has only cultivated one species with the potential for interstellar travel. I remember an old adage that if the age of the Earth was converted to an hour then humanity would only exist for a second.
> 
> I still think the Fermi paradox holds true as a single race with interstellar caperbility should be able to colonise the galaxy in a relatively short time period (by that in at least 50000 years assuming they can get to light speed) There's simply no verifiable evidence. Once a race goes interstellar it should be 'future proof' (barring truly catastrophic events like gamma ray pulsars) and the continuing expansion of that races terratory.
> 
> All it would take was one of those species gestation to have occurred a 'couple of minutes' before us and they should be everywhere.



To expand on that, I once heard that if the entire lifetime of the universe was superimposed on a single calendar year, then all of (earth-based) biological evolution would have occurred in the final seconds of the year. So just imagine how many chances for complete biological evolution there must have been throughout the existence of the universe. Just makes you wonder what's going on up there....


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## ralphkern (Mar 31, 2014)

The simplest solution to the Fermi paradox is that humanity is alone, always has been always will be. We are a fluke. Doesn't quite ring true to me. 

Another is that we are the first. Again considering how much time has elapsed since the start of the univese, it seems wrong.

The 'quarentine theory' is a bit too far fetched. If we look out into space we should see signs everywhere, whether it's Dyson spheres of a type 2 kardashev scale civilisation or just simply alien soap opera transmissions. But still hiding all that from our view? 

The berserker species idea seem a little too out there. All it'd take is one species to fights back and we should be watching the battle play out all around us. 

There are many more theories but they are the ones that are most often cited as the reasons why we can see no one else


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## Nick B (Apr 1, 2014)

It took 4 billion years for the Solar system to sort itself out enough to end up with a a race that can build primitive spacecraft. In our evolution there was also (apparently) a massive jump where in 50,000 years our brains evolved at a ridiculously fast rate, this fed many of the ancient alien theories out there.
If that is an average evolution from new star forming to intelligent life building a spacecraft then is it all that surprising that we havn't heard from anyone?

There could be thousands of fledgling intelligent races out there. Given another few thousand years teh galaxy could be teeming with races expanding their territory.

On the other hand, maybe we are simply in a quiet neighborhood, maybe on the other side of the galactic core there are already hundreds of races fighting it out, or members of a peaceful super culture. If there are then maybe they simply havn't been broadcasting anything long enough to have reached our primitive listening devices.

Or, maybe we are alone.

I don't know which is more frightening, that there are aliens whizzing around waiting to find us, or that we are totally alone in a huge universe.


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## ralphkern (Apr 1, 2014)

To be honest, yes it is surprising. 

The Fermi paradox is such a fascinating topic for me since I first read it in Stephen Baxter, so much so that my own novel is my own take on the solution. 

At the moment we have evidence for but one intelligence with potential star faring status... Us. For the last 60 years we've been loud and proud about our presence, shooting off EM in every direction. I'm going to simplify the argument (not through patronisation, but for ease of articulation). 

The above article states that there are 11 billion 'Earths' in the galaxy. Now, let's say that the galaxy had been 'habitable' for 11 billion years (universe being 14 billion years old). Then if each of those 'Earths' can gestate one intelligence on average then we are looking at the galaxy cultivating one intelligent species on average,every year. Due to various reasons, atomic level baking of elements etc, I would suggest we would, or should, see a lot more of those gestations in recent times than primordial times (by recent last several billion years). 

Still if even one of those races had been a breakaway success,they would have been unstoppable in terms of their colonisation efforts. 

We can even tweak our fudge factor and the numbers are still impressive:

If out of our 11 billion earths, 1/1000 cultivated star faring intelligence then we get 11000000 races pottering around the galaxy.

If 1/1000000 earths, or one in a million then we have 11000

One in a billion is 11

All it would take is one, whichever figures one feels is correct, and that's it... That race should be over a relatively short space of time be colonising the galaxy, and over a very short space of time, relatively speaking. 

And consider detection doesn't necessary involve the mothership visiting Earth. Everything from radio transmissions to them constructing Dyson spheres to who knows what, but unmistakably the sign of intelligence, should be observable.


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## Nick B (Apr 2, 2014)

It is fascinating. Personally I think the universe is most likely teeming with life. Intelligent life? Maybe, maybe not, but looking at where life exists on Earth where we once believed no life could exist, then the likelihood of life elsewhere in our solar system is actually fairly likely, let alone the rest of the galaxy.

The problem I think maybe in our expectations of life developing complex intelligence such as ours. How do we predict the chance of that occurring? I don't think there is a reliable method of predicting the chance of intelligence emerging.

I would love contact to be made in my lifetime, the thought also terrifies me, probably because I have children.  If aliens turned up with hostile intent, even aliens just say, a thousand years more advanced than us, a mere blink of the galactic eye as far as time goes we wouldn't stand a chance.  As Michio Kaku said, it wouldn't be a David and Goliath scenario, it would be more like Kermit the Frog versus T-Rex.

The paradox still stands though, if there is _anyone_ out there, let alone the many races we should be expecting why have we heard nothing at all?  

Maybe the upcoming film Jupiter Ascending is right and we are being kept in the dark by some galactic community. I wouldn't blame them, we are pretty unstable, we can't even stop killing each other let alone anyone else we might meet.

As an amateur astronomer, I always find it fascinating that you would think if anyone would be likely to see an alien spaceship, it would be an astronomer but it pretty much almost never is even though we are the people with our eyes on the sky more often than anyone.


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## ralphkern (Apr 4, 2014)

That is one of the reasons I made the distinction between 'Intelligence' and 'life'. Without going into ethical debates about whether a dolphin or whatever is intelligent, I wanted to keep the two distinct.

Like you I find the prospect that life out there a probability. 

Take, for example, one of the most habitable seeming planets that has been found on the exoplanet surveys. Gliese 572 D around 20 light years away. Scientists strongly believe that this could well be an 'ocean world'. They think the majority, if not all, the surface would be covered in a deep ocean. 

There are two big problems with the world though, assuming it is as postulated. 

1. It is covered by an ocean, and as such any life, even if intelligent, likely would skip combustion technology, it probably wouldn't even factor into their thinking, much like the wheels and Mayans. Without that, most of the technologies we take for granted simply would not exist. 

2. The gravity well is 5 times that of Earth. Combining that with the fact that any intelligence would undoubtedly be water based, they would view even heavier than air flight as not worth their bother, let alone crewed space flight in a craft they had to launch against that gravity full of water.  

Just because a world is conducive to life, or even conducive to some form of intelligence, space faring is not a natural extension of that. 

Of course, they may well have imaginative solutions to these problems, that we would simply not even think of, but still, there are certain 'basics' that they would have to overcome. 

Stephen Baxters book, Evolution, even postulates that the pinnacle of evolution of a species is not, in fact intelligence. In fact it may eventually be discarded as an evolutionary dead end, no longer needed for the ultimate survival of humanity.

In relation to the unstable factor, it is a thought. I would suggest, to play devils advocate, that a certain aggression in terms of expansion could well be a prerequisite of any race that seeks to become space faring. One just has to consider the advances in the World Wars and Cold War and many other conflicts. 

Pleasant? No. 

One of many possible prerequisites for space faring? Could well be. The Cold War certainly drove the moon landings which in turn was based on technology that was developed in WW2.

Personally I have another theory as to the solution to the Fermi Paradox, but that would be a spoiler for my own novel which covers this topic.


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## Darth Angelus (Apr 4, 2014)

I never found Fermi's paradox, or rather, its argument, to be particularly persuasive. Or perhaps more accurately, I do not think it means we ought to be surprised by the fact that we have not heard from anyone. There are still plenty of unknown factors concerning how hard it would be for species capable of interstellar travel to evolve (and how long they would last), and those who feel confident galactic civilisations should exist seem to have filled these gaps in our knowledge with optimistic assessments (or should I say "assumptions").
Several possible answers are presented in the Wikipedia article on the subject, and most of them seem at least plausible. It could be pretty much any of them, or a combination of several.

The most tragic solution to the paradox is that intelligent life wipes itself out (or, somewhat less grim, knocks itself back to an earlier stage technologically) before attaining interstellar travel. Or, various types of astronomic or natural disasters could do it. However, one does not have to go there.
It may not be possible (within physics) to develop technology for travel to the closest habitable planet (we don't know how frequent they might be) in less than several generations. It may cost incredible amounts of resources to make such trips, far more than it would save from the planet of origin in less than incredibly long term, which would make it an act of incredible altruism for whoever financed it. Indeed, it may even be an act of incredible altruism to embark on a journey into the unknown, never to see home again (and for your children and grandchildren to spend their entire lives on a space ship) for the possible benefit of civilisations of future generations. It may be beneficial for the survival of a species to not have all eggs in one basket as in all living in one place, but that doesn't mean it is beneficial for the individual. And evolution is about survival, ultimately on an individual level.
It could be something along the lines of Star Trek's prime directive, or them avoiding us for some other reason, such as that we are not interesting to a species capable of interstellar travel, frankly being animals to them.
There are plenty pf more possibilities tat can hardly be ruled out. And again, it could be almost any combination, with thecumulative effect of making galactic civilisation highly unlikely. Just a couple of them in unison should make galactic civilisation unlikely enough.
We may never know what the actual explanation (or combination of explanations) is, but with so many possibilities, I see no reason to be surprised we have heard nothing.


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## ralphkern (Apr 4, 2014)

The paradox isn't an argument in itself, merely a question that has provoked many a debate. Which as you say, sadly, we may never know the answer to.

We can't even start unless we get some hard numbers for the Drake Equation which only an omnipotent being would know (or a thorough survey of the universe)

I am a strong subscriber to the camp that believes that once a civilization achieves star faring capability... it should be everywhere though.


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## quantumtheif (Apr 5, 2014)

They are still creating that new satellite that specifically searches for possible water planets in the Goldilocks. I think it called the MIVEN, but i'm not sure. I hope the program takes off.


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## ralphkern (Apr 23, 2014)

Exciting news:

Kepler-186f - Wikipedia, the free encyclopedia

First roughly Earth sized planet found in the Goldilocks zone.


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