# Alien Earthlike worlds 'like grains of sand', say 'wobble' boffins

In a boon for those anticipating future discovery of alien life and/or human colonisation of other worlds, NASA boffins say that their latest analysis indicates that almost one in four stars may be orbited by planets as small as Earth. "We studied planets of many masses - like counting boulders, rocks and pebbles in a canyon …

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1. #### The Drake equation

Come on someone:

N = R* fp ne fl fi fc L

where,

* N = The number of communicative civilizations

* R* = The rate of formation of suitable stars (stars such as our Sun)

* fp = The fraction of those stars with planets. (Current evidence indicates that planetary systems may be common for stars like the Sun.)

* ne = The number of Earth-like worlds per planetary system

* fl = The fraction of those Earth-like planets where life actually develops

* fi = The fraction of life sites where intelligence develops

* fc = The fraction of communicative planets (those on which electromagnetic communications technology develops)

* L = The "lifetime" of communicating civilizations

(from http://www.setileague.org/general/drake.htm)

Where's my alien overlord and their flying cars!

ttfn

1. #### the Drake equation is based on speculative assumptions

I'd like to think we aren't alone, but that would be simply an emotive argument, rather than a scientific one.

We don't even know HOW life occurs, thus we have no idea how likely it is to occur anywhere else. Without knowing such a basic pre-requisite, it's impossible to even begin to guess (because that's all we're doing) whether we are alone.

e.g.

If X = number of suitable planets in the universe, and the P is the probability of life occuring, then if P = 1 / (10 * X) then we've beaten the odds to be here and are likely to be on our own.

On the other hand, if P = 1 / (X / 10) , then there should (on probability) be nine other instances of life out there.

The problem is, we don't have any idea what the value of P is, other than it can't be zero (because we are here).

Thus, the only reasonable answer to the question of whether we're alone or not is :

"We don't know."

2. #### You forgot a term...

B6 = the amount of bullshit you're willing to buy from Frank Drake.

http://xkcd.com/384/

2. #### Get it right Reg.

Earth-like and Earth-sized are not the same thing. Until we can analyse the light coming off these worlds they will only be lumps of rocks.

Let's not get too excited eh?

3. #### No one would have believed

in the first years of the 21st century...

1. #### Slowly, but surely, they drew their plans against us.

Daa Daa Daaar!

That is all.

1. #### Ullaaa....

Uuuuullllaaaa......

2. #### @Andy and Cowherd

You two are WoW nerds. (Or should it be WotW?)

1. #### No! Prathlev no,

There must be more to life....

:)

oooo-laa!

ooo-la!

2. #### In the first years of the 21st century...

...the very first endosymbiosis of a prokaryote occurred on Alpha Centauri B II. The symbiont rapidly divested itself of excess genetic complexes and became totally dependant on the host cell. Fortunately, the symbiont provides the host cell with a method of producing energy it had heretofore previously not had. Soon, the cell divides; it’s new companion along for the ride. Another division, and another. Alien microbes have developed the mitochondria!

Evolution occurs at a furious pace; the alien eukaryotes develop into multi-cellular organisms of increasing complexity. They prey upon the hapless prokaryotes that surround them becoming more and more fit; more capable of adapting to new and different environments. This new life is on the verge of bursting forth from its ecological niche and unleashing a torrent of advanced life on it’s planet.

Suddenly, a shadow falls upon the small pool where these prokaryotes have evolved. Sunlight glints off of a foreign metallic tower. It must stretch a meter into the air…what could it be? An arm lowers itself into and with a small container scoops up both the tiny pond and much of the surrounding soil. Up through the air the entire mass is lifted, until it is deposited into a bin on the back of mysterious metallic device.

The temperature rises. The water starts to boil. The prokaryotes cannot adapt quickly enough to their new environment and they quickly perish. The newly evolved eukaryotes survive for a minute longer…maybe two. The probe finishes analysing the results of it’s findings and transmits the information back to Earth. Fiver years later the news electrifies the world:

…on a planet not to far from home, we have found life! Liquid water and the chemical signatures that indicate our faithful rover has boiled itself some bacteria! Disinterested with the news – Earth was really hoping for something more advanced than bacteria – the Rover is left to continue its journey until it fails. Ultimately, it is abandoned: the lone ambassador of a planet that won’t be returning to reclaim it. It’s sensors left to gaze upon the planet whose future it had accidentally destroyed.

Moral of the story: don’t boil your neighbours, mmmmkay?

4. #### Hell yeah!

There's accessible resources on smalltime boulders out there.

Where's my Weyland-Yutani? Where is my Nostromo and my crappy interstellar 'sploitation job?

5. #### I can't see them either

"Our ground-based technology can't see the grains of sand, the Earth-size planets, but we can estimate their numbers," says Andrew Howard, boss scientist of the team conducting the study.

The result?

"Earth-size planets in our galaxy are like grains of sand sprinkled on a beach - they are everywhere," says Howard.

This just in:

I can't see them either, so I estimate there are at most 42 Earth-size planets in our galaxy.

1. #### "so I estimate there are at most 42....."

I guess the downvoters haven't read "Hitchhikers...."

6. #### "Where's my alien overlord and their flying cars!"

Very good question. Even at sublight, it should take at most 100 million years for a species with just 2% growth rate to colonise the entire Milky Way.

So either we are the only technological spacefaring race that's ever evolved in the (literal) entire history of the universe, or... maybe we shouldn't be broadcasting our location.

1. #### do the calculation properly

(and ignore the Drake equation guesstibollocks)

2. #### "we are the only technological spacefaring race ....."

OR the only method of travel is sub-light and too slow and energy intensive to allow any sig. expansion

3. #### Keep quiet when you don't know who is there

It might be the equivalent to chattering away when the wolves are about on the prowl

7. #### So there may be plenty of small rocky planets

Fair enough. The number with temperate conditions and suitable mineral/liquid/gaseous resources that actually go on to develop carbon-based life forms that evolve into intelligible communicative beings remains to be seen. Our own planet has not yet satisfied the last criterion.

1. #### I think you meant intelligent...

not intelligible, which means "capable of being understood or comprehended". For example, you are intelligible, I could understand what you wrote, and even figure out what you were probably intending, however, I have no evidence that...

No, no, I'd better not go there. Suffice to end with the pedant icon.

2. #### Assumption

Of course a lot of them will have formed a long time before the solar system that we live in so could well have evolved millions of years more than ourselves, become extinct or already colonised vast numbers of planets themselves in the search for resources.

8. #### So....

When's the interstellar version of PARIS coming off the drawing board?

9. #### 46 billion Earth-size planets in our galaxy :)

Yet there's also an estimated 170 billion galaxies!

So much for scifi saying Earth planets are a rare resource. :)

10. #### even at sub light?

Even at sub light, we don't know if it's feasible for living organisms to travel in interstellar space. If you look at the rocket equations it's ridiculously difficult. Which also means ridiculously expensive. Who would pay for it?

1. #### i would...

just to find some intelligent life... cos there is bugger all down here on earth :D

2. #### I can answer that one...

Any civilisation that realises their sun is going to explode soon. When every building on your planet is going to get vapourised, then even the chance to invest in an off-plan development on a planet that might be orbiting a star several light-years away begins to look attractive (as long as it includes a seat on the shuttle-bus).

The salesman really isn't exaggerating when he says it's a one-in-a-lifetime opportunity.

3. #### "we don't know if it's feasible for living organisms"

Pfft, living organisms? Self replicating robuts are more likely. Or if you want to spread a meat-species infestation, grow them in a vat when your craft reaches Ceti Alpha Sheldon. Marlon Brando can provide Teachamacrystals.

The universe has had 14 billion years to produce ONE species or technology that can spread between the stars. It would only take one. One single spacefaring species in 14 billion years. So where is it? Where are the signals lighting up the heavens? Where's the evidence of our solar system being strip mined at any time during its 4.6 billion years?

The simplest explanation is that we're alone. Either that, or that the entire Galactic Federation is saying "Shhh, everyone be quiet until these monkeys wipe themselves out."

1. #### indeed we do not know

"The simplest explanation is that we're alone. Either that, or that the entire Galactic Federation is saying "Shhh, everyone be quiet until these monkeys wipe themselves out.""

The latter is correct. It is all due to the game of cricket! Aliens find this in very poor taste.

4. #### @Bounty

Best not to use rockets then!

11. #### @ Steve x

You mean the Paper Airplane Released into Interstellar Space?

1. #### airplane

Astroplane, surely?

12. #### You're looking in the wrong places...

Everyone knows they all live in habitats like orbitals... and GSV's.

13. #### Bottom line

In the shitty housing estate I live in, there's at least three out of 500 people are cool as fuck.

14. #### Hmmm....

I thought that life on Earth was partly possible because of Jupiter hoovering up all the stray planet-smashers for long enough to let something more complex than bacteria to have a chance of hauling up out of the ooze.

Plus, the impact early on with a near-earth-sized planet in the same orbit that gave rise to our abnormally large moon and gained Earth enough mass to hold onto a substantial atmosphere (not to mention the spinning iron core generating a strong magnetic field to deflect nasty stuff).

So, might I suggest that scientists first start considering *only* those solar systems where a large Jupiter-like planet exists, otherwise there'd be nothing but large rocks that hve been repeatedly used for asteroid and comet target practice. Some how I don't think that just picking a random 'grain of sand' is going to be too successful, even just to run a spectrographic analysis of any nacent atmosphere present to work out if there's water vapour, oxygen, and other signs of respiration in the biosystem.

15. #### The problem...

...is that George Lucas designed them all, so you get Desert Planet, and Water Planet, and Lava Planet, and Ice Planet, and Forest Moon, and Jungle Moon, and City Planet, and Grasslands Planet...

Alien, 'cause he kinda reminds me of Greedo. You know, the Greedy Alien.

16. #### Who would pay for it?

it would be free ..with ads all around it ..and cookies that last for tens of thousands of light years ..

see Eric ..we know what you are misthinking.

17. #### Alas, there's not much we can do about it...

... until someone discovers an as yet unknown law of nature that enables faster than light travel.

The reality is, even getting to the edge of our solar system - the Oort cloud - is about a light year distant.

With the fastest spacecraft travelling away from the earth at around 38,000mph (Voyager 1), it would take thirty thousand years to reach the outer boundaries of our solar system.

Getting to Proxima Centauri would take 81,000 years.

"Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space."

18. #### Maybe WE are the saddos at the end of the universe

The rest of the universe parties on while we are ignored....

19. #### A lot of people wonder why

Why, if an advanced spacefaring alien race exists, that they have not visited us.

Perhaps the answer is really simple.

We are not interesting, we have nothing they want or need, that they cannot get else where with less hassel.

Most of us make a starteling presumption, that we are something special, or that we are enormously interesting,

Presuming that some of these poential aliens, have poentially had billions of years of advancement ahead of us, it's a huge presumption that we'd even detect them if they were visiting...

Many less developed societies, consider our "modern" technlology magic, because they cannot comprehend them, it's likely that it would be simlilar from our point of view, if a sufficiently advanced civilisation existed.

Also trying to detect a spacefaring civilisation would be per definition, impossible, because we do not possess the ability to communicate nor travel faster than light. Thus the technologies that allows FTL communication or travel, would be beyond our abilities to even detect.

20. #### Energy Required.

As well as the time taken to get to any other earth like planet at less than the speed of light, it seems to me there is also the issue of the required energy. I was under the impression that you had to put ever increasing amounts of energy to get to any fraction of the speed of light. Given that you also have to expend energy to slow down again, that seems to me that one is going to need to use some sort of fusion power and we don't even know how to build a fusion reactor here on earth let alone one that could be contained in a space ship.

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2. #### Energy Required. →

True enough about the energy demands but it is truly awesome. To get 1 tonne to 10% light speed takes the equivalent of ~1e11 MW.hrs and the same again to slow down

( or ~~£10 billion at UK electricity prices )

21. #### Yah yah yah

Stars in my pocket like grains of sand. I like it.

And it'll give the yanks something else to scream about.

22. #### It's entirely possible...

...although I know it's hopefully unlikely that we've realised the maximum speed that we can reach, and thus interstellar travel is just not possible.

Don't get me wrong, I hope against hope that it isn't the case...but there is a distinct possibility that no matter what is out there we aren't going to reach it....not without generational ships anyway - or some sort of foolproof system for suspended animation of a human being.

So as much as I value the expansion of knowledge of the human race, I'd like to see how this supposition/estimation is going to give us extended lifespans, inexhaustible (or as good as) fuel supplies, inexhaustible food supplies or even just make life better.

23. #### Close & Protected...

The transition to a new planet needs that it be close & protected much as we are by Jupiter & needs to be close to its own star so that there is warmth otherwise all this is smoke...

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