Wednesday, February 23, 2011

Of Kepler and Fermi

Last time I left off talking about the cosmic lottery. We are pretty lucky to be around, and just how widespread that luck is. Estimates say there are roughly 500 million planets in our galaxy residing in habitable zones, 500 million chances for life to arise at any given time. And not all these might seem obvious at first; a few might turn out to moons orbiting giant planets.

The number of planets that will actually have life will turn out to vary from this a bit. There is a great diversity in planets and the right conditions need to be there. In our own solar system, it is accepted that Venus is at one end of our habitable zone and Mars is at the other. If conditions were different on these planets, life might have taken hold, and it might have even been there in the past. In our search of these 500 million candidates, we will find lots of planets like Venus and Mars. Either too small to retain an atmosphere against the solar wind, or to thick of an atmosphere with a runaway greenhouse effect. A lack of a protective magnetic field or plate tectonics. Objects like the Moon and Jupiter that protect against asteroids and comets. And a stable, long living star.

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Those are just a few of the conditions needed for life to develop into a complex form. And some people talk about colonizing other planets, but planets that we will be looking for will have these conditions, and native life. How we would handle that native life if we got there to colonize is just one of many problems to figure out. To we become hostile to it, do we study it, do we leave it be? Those are questions for the future.

But in the search for these ideal places to live, we will probably find less then ideal, but still great places. On these planets we will likely encounter our first alien life forms. Bacteria and Archaea like lifeforms, probably reminiscent of the extremophiles found all over Earth. Extremophiles live a variety of environments that might otherwise be considered inhospitable. They live in thermal vents under the ocean, in radioactive cooling pools, under kilometers of dirt, in sulfur or arsenic rich bodies of water. They are unique and amazing lifeforms, and likely the first that even developed on Earth. These little guys helped to shape and change the environment of the Earth, producing oxygen and changing the surface so that life could further grow and flourish. They also have an amazing tenacity for life, making them the ideal candidates to look for out in space.

The existence of extremophiles also does something to the idea of the habitable zone, it makes it all but defunct. It may prove that life is capable of sustaining itself in a dark ocean locked under ice on one of Jupiter's moons (Europa). Or even in the far flung space between stars, deep in the surface of planets cast off from their parent star, near radioactive heat sources.

So that's all fine and dandy for our first encounter with alien life and the exploration of colonize-able planets. But the idea of intelligent life is still one of the most argued questions. It is shown now that there is good cause to believe its out there. Though, it might turn out we did hit the 1 in 500 million lotto odds for our galaxy, or even larger odds for the Universe. So let's start with what it would mean if we are the only ones.

If we are it. If human kind is the only intelligent life form in the Milky Way, then we have come from amazing odds. We also have a whole Galaxy, at least 100 billion stars, to do what we want with. The first thing is that we should immediately preserve our home. It has become the precious jewel of our galaxy. In addition, we begin populating the galaxy. Use all of its resources to great potential. The human race may then long outlive the death of the Sun, and with it the Earth. But that flourishing will be humanities ultimate achievement, to escape their planet and become a galactic civilization. Research then would go to unbelievable new levels, the ideas of which are probably beyond our comprehension now, like our thoughts would be to the neolithic man. Life would be special in this scenario, and humans would be its gardeners throughout the cosmos.

Now, I don't really agree with that, but its a certain possibility. More likely, I feel that intelligent life is out there, and they may be roughly around the same level as we are. Super-intelligent civilizations, or those unrecognizably advanced beyond our own, are for another time. So if they are out there, where are they then? We raise the 'Fermi paradox,' with the contradiction between the high estimates of in the probability of extraterrestrial civilizations, and that there is a lack of evidence or contact with them.

My answer to the Fermi paradox is that the estimates aren't so high as to negate the immense size of the Milky Way. Much like to the ancients considering the celestial sphere and motions of the stars, arguing heliocentric versus geocentric theory. In that case of early astronomy, the stars were much to far away to measure parallax (an interesting subject on its own); now it may turn out that the distance between intelligent civilizations is to great to get a message across. Sorry, but here I am about to drop some math on you.

I am going to assume that the distance of the Sun from the center of the galaxy is roughly where most life is distributed, and that number is 26,400 light years (lys). I won't burden you with the circumference equation, but this region comes out with a circumference of roughly 166,000 lys. If we assume intelligent life to be 1 in a million chances, that gives us 500 civilizations, a pretty reasonable seeming number for any galaxy, right? Well, dividing our circumference up by 500, assuming they are roughly equally apart in distance, these civilizations would be about 350 lys apart. Imagine sending a message at the speed of light, waiting for someone to receive it, and then respond, That would take 700 years at minimum! No wonder we haven't found anyone yet, we might have even missed the message, or it might not have even gotten here yet.

We are just on the cusp of being able to detect messages from outer space, we may have to wait another half a millennium before we even hear from another civilization at our own level. Who knows, we might be surprised by some bright guys out there though. In the mean time, humans ought to just keep expanding, we have a good couple hundred light years to work with. We might as well expand into the stars. This post was much longer then I anticipated, but I hope you enjoyed it, I enjoyed writing it. I'm probably taking tomorrow off.


25 comments:

synoptixs said...

there has to be some kind of life form out there, whether it be a plant or an intelligent being

Charles said...

exponetial technology... I hope we can find something in our lifetimes, that would be killer

Aaron M. Gipson said...

I heard one interesting theory… What if we're not the only intelligent life in the Milky Way, but the first? What if it turns out that humanity was destined to be the elder species of the galaxy?

Lost.in.Idaho said...

I had to read it twice to make sure I absorbed the full post...

To take what Aaron said and build on it. We could be the first, we could be in the middle, or we could be one of the 'younger' civilizations. But to say we are alone seems egocentric.

Astronomy Pirate said...

@Aaron, that is also a possible concept. From what we know of life on Earth, life tends to arise whenever it can, at the earliest possible moment. But we also know that the Earth had a few false starts and radical changes in body plans. So perhaps we are the galaxies first intelligent civilization, arising at the earliest convenient time. Hopefully we aren't a false start, but some days I wonder. If we do make it, and it becomes us who are eldest, how will we react with younger civilizations?

kgp318 said...

I as an elem ed major haven't really thought about other life forms as a scientific topic...we are only taught what is in objectives of learning (state testing etc.) It would be really interesting to see what the younger generations will find out...what will my students live through and learn through scientific discovery? and in that notion what should I teach them in science? Just thoughts...

Matt said...

One of the most frustrating things I learned in physics class is that you can't (as far as we know) break the speed limit (go faster than the speed of light). This frustrates me because it therefore limits our communication and travel to c (at the max, in reality most likely much less for travel), which makes the galaxy a very biiiiiiiiiiiig place. Great post!

ScottD said...

The galaxy is so big to contain and prevent virus like us from spreading.

Jack Bosworth said...

I always remind myself that if life hadn't in fact emerged, then we wouldn't be sitting here talking about it. But that's just me, very interesting post (followed!) :D

Space Marine said...

mind blown

Anonymouse said...

cool blog now following.

rndmg123 said...

the universe scares me

ThingsIThinkAbout said...

^^^ "the universe scares me"

I agree. Reading about this stuff blows my mind.

Julien Wood said...

Personally, I am absolutely convinced in intelligent life living in our universe.

tcrosso said...

With the size of the universe as it is at the moment, there is absolutely no way we are the only intelligent lifeform. Infact I believe there is extremelly advanced and different types of lifeforms out there. It's a pity we will never know (or will we :D)

HillDog said...

There just has to be life somewhere else. I know it...

Ashton Chase said...

I guarantee there is other life out there. It's just highly unlikely we will ever find them or meet them as the universe is simply to large for us to travel even at the speed of light.

Jeff said...

Yup we're a tiny spec in this universe. If there is (and most likely there is...) life out there we should all have a huge party. Just saying...it'd be fun right? If they didn't try to obliterate us and just played twister.

PekkaK said...

Future will be very interesting for us... will we find habitable planets? I think so.

LifeHacks said...

That a great piece, I love astronomy. I believe that we will travel to other inhabitable planets within the next couple hundred years....

Charmander said...

I can't fathom there isn't intelligent life out there. Will we ever see them or contact them? That i doubt. I cant picture a civilization becoming so advanced it travels far enough out into space to meet another one

Fourra said...

man i'm lucky!!!!!!!
or NOT :)
"lucky or unlucky, you never know!"
Chinese Proverb

G said...

Would we recognise a signal if we picked it up?
We're now moving to digital communication after only a relatively short period of using analogue... Analogue is probably easier to detect but we've only a very small development window to pick it up....?

Astronomy Pirate said...

@G, That's another problem, we might have already seen a signal (the WOW signal), but never heard it repeated. The hardest thing to know is what to look for, we can only guess from what we know and have available to us. And if nothing is looking at that part of the sky, then the signal just gets missed.

YetAnotherUnreadBlogger said...

I always love reading about things like this, and the idea about humanity being the first intelligent life really intrigues me...

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