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Is the Earth Special?
Hugh Pickens writes "Planetary scientists say there are aspects to our planet and its evolution that are remarkably strange. In the first place there is Earth's strong magnetic field. No one is exactly sure how it works, but it has something to do with the turbulent motion that occurs in the Earth's liquid outer core and without it, we would be bombarded by harmful radiation from the Sun. Next there's plate tectonics. We live on a planet that is constantly recycling its crust, limiting the amount of carbon dioxide escaping into the atmosphere — a natural way of controlling the greenhouse effect. Then there's Jupiter-sized outer planets protecting the Earth from frequent large impacts. But the strangest thing of all is our big Moon. 'As the Earth rotates, it wobbles on its axis like a child's spinning top,' says Professor Monica Grady. 'What the Moon does is dampen down that wobble and that helps to prevent extreme climate fluctuations' — which would be detrimental to life. The moon's tides have also made long swaths of earth's coastline into areas of that are regularly shifted between dry and wet, providing a proving ground for early sea life to test the land for its suitability as a habitat. The 'Rare Earth Hypothesis' is one solution to the Fermi Paradox (PDF) because, if Earth is uniquely special as an abode of life, ETI will necessarily be rare or even non-existent. And in the absence of verifiable alien contact, scientific opinion will forever remain split as to whether the Universe teems with life or we are alone in the inky blackness."
Didn't the Earth get hit by another planet, causing it to shoot a ton of crust into orbit..creating the moon?
Clearly, life requires a mars-sized object to hit the planet where life wants to form.
While most planets are obviously not suitable for life, life itself has a strong tendency to overcome the challenges of its environment. Life endures climate fluctuations, extraterrestrial impacts, and even extreme radiation, all here on Earth. While many of these protective characteristics are conducive to the emergence of higher life, life itself has already shown its capacity to adapt and overcome.
All life really needs is a liquid solvent, energy, and enough time.
I can already hear the "intelligent design" folks jumping on this topic as proof that we aren't here through random chance but were assembled by some creator. Just as an FYI, the "rare earth hypothesis" has been circulating in the scientific community for many years.
"We make our world significant by the courage of our questions and by the depth of our answers." Carl Sagan
Why are conditions that promote life rarer than ones that prevent it?
Hey, how's it going?
All 7.5 of them born every single minute in the U.S. alone.
Source: http://www.census.gov/population/www/popclockus.html
( Although I have to admit, that 0.5 baby is pretty darn special. )
Maybe they should define the lower bound for 'special' before even pondering whether or not the Earth falls within the definition. Then, if it doesn't, they can raise that lower bound until it does.
"In the air, there is no way for Oxygen to enter our gills. Therefore, water is extraordinary!"
This is the same thing religious leaders expouse, "what we can't explain must be special and unique". In a universe, nothing is unique. Except for snowflakes.
Agreed. Because life evolved a certain way here, and under certain conditions, doesn't mean that it can't evolve in a different way elsewhere, on possibly more (or less) challenging conditions. As long as you have variations and some selection mechanism, you'll get evolution (within reasonable bounds, of course).
"You know, the most amazing thing happened to me tonight. I was coming here, on the way to the lecture, and I came in through the parking lot. And you won't believe what happened. I saw a car with the license plate ARW 357. Can you imagine? Of all the millions of license plates in the state, what was the chance that I would see that particular one tonight? Amazing!"
Just because our "route" resulted in our "life" situation, doesn't mean that other routes couldn't produce equally valid and viable "life" conditions. We're not that special.
My UID is prime!
...is a civilization of creatures living in a vast ocean of sulphuric acid (or some such), with scientific laboratories we would dismiss as "collections of rubble," that are wondering the same thing about THEIR world...
We'll never have a common language with them (they're telepaths, you see; think only rocks breaking against each other generate sound waves), and for eternity, we will live in parallel with them, and never interact with each other: Two species, forever locked in their own myopia and confident their science is telling them "We're SPECIAL."
What an incredible egos must Seven Billion creatures have.
Damn right! We call it Terran Exceptionalism. I'm sick and tired of all these "elite" types running around apologizing for Earth all the time!
XML is like violence. If it doesn't solve your problem, you're not using enough of it. --AC
What's exciting about the recent exoplanet work is that we're actually filling in the first few parameters of the Drake Equation. We're getting a grip on how common planets are, and now how common it is for them to be (a) not gas giants and (b) in the right zone around the star. I think those two alone (combined with "how many stars are like ours", which we have known a long time), knock off a good four orders of magnitude - from hundreds of billions of stars in this galaxy to tens of millions that are 1) not short-lived stars ; 2) have non-gas-giants that are 3) in the "habitable zone".
We already know enough from extremophiles on earth that anything with liquid water, practically, is "habitable zone".
What we can get from just closer examination of our own solar system whether life NOT "as we know it" happens - did it arise in liquid methane, or floating about in Jupiter's atmosphere and all that. And if it does, how complex does it get?
These "special conditions" may not be necessary for *life*, but they may be necessary for it to bother (sorry, "have reproductive advantage") going past single cells, which biologists still consider a pretty Great Leap Forward.
It may well be; until we're not extrapolating from one data point, speculation is just entertainment. If it turns out complex life happens only every trillion stars and there's only one other in the "local group", ten million light-years from here, well...rats. Just ourselves to talk to.
Console yourself with this: it means our celebrities are even MORE important than we ever imagined. "Miss Universe", for instance, really IS Miss Universe!!
If our solar system is so special that it is one in a million then there are about 200,000 systems that are as special as ours in the Milky Way. Multiply this by 100 billion to one trillion galaxies and we are really not that special.
Facts take all of the premium out of arm waving - T. Reynolds
Boobs.
Now I like boobs as much as the next guy. As a matter of fact what got my mind started down the track is staring at alien boobs on all of my favorite SciFi movies and I started thinking to myself "You know, those are kind of weird as far as life is concerned".
I'll use life on our own planet as an example. Only mammals have boobs.
Other animals do indeed feed on another, there's a lot of really unappealing vomit sharing in many types of life and poop sharing in the insect world that I think would probably be more common among the stars (Slurm for example) as it's even more common here. There are nutrient transfers that happen on our planet that are different than the insect ones I just mentioned might be out there as well as some we haven't thought of, but I keep thinking of boobs, cause I think of them all the time, and I just don't see them as something that are likely to exist on alien babes. I'm not discouraging my favorite Sci-Fi writers by any means, whatever happens keep the boobs on your alien babes, but when I think of the possibility of meeting real alien babes it saddens me when I realize evolution is unlikely to have included boobs into the equation.
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That's no moon... it's a terrestrial wobble dampener!
The Earth is special. Humans are only here because of the great beardy guy in the sky. Now that this massively important issue is settled can we get on with colonizing Mars? Please?
Having to work for a living is the root of all evil.
It seems that life, intelligence, and civilization are the things that we find most interesting, in ascending order, when discussing exobiology. And, in ascending order, much, much more difficult to achieve. In other words, simple life is almost common, complex life is rare, intelligence even rarer, and civilization the rarest of all. Each step requires more time, stability, and opportunities for differentiation, than the last. A lot of the uniqueness of the Earth, according to the article, has to do with its suitability for developing land-based life. I wonder if achieving a land-based civilization is rarer than a liquid-based one. If there are aliens sending probes over here to investigate us, maybe it's to study this weird, land-based civilization. I admit that one advantage to land-based life development is that it's much easier to form divided ecosystems on land than it is in an ocean. This could create more opportunities for divergent evolution, speeding things up if you want to see a particular result, like intelligent life. However, it seems to me that there could be situations on other planets that can create a similar effect in a liquid environment. Perhaps not common, but possible. My point is, it might be chauvinistic to focus so much on conditions that allow the development of land-based life. The other, hidden chauvinism is towards carbon-based life, but it's hard to blame ourselves for that since it's so difficult to figure out how other kinds of life could work.
Rare Earth: Why Complex Life is Uncommon in the Universe
I found the chapter on plate tectonics very informative.
How do you know WE aren't the extremophiles?
Oceans full of a solvent, we breathe a caustic gas... and so on.
Out of modpoints but really liked a post? 1BDkF6TtmmeZ3yqXbz9yhdYVqRYnwFoXDj
I think it would be hard to find another identical Earth with a Moon of the same size as ours, but on the other hand - life can appear under for us strange circumstances. Just look at the fumaroles in the oceans - they have a life that's different from what we really recognize usually.
However even if many planets out there are either like Venus (hot and dense atmosphere) or Mars (thin dry atmosphere) you may be able to see planets that are similar to earth from many aspects, even if they may have a more intense gravity or other differences. But they can probably sustain life. The point with Earth is that some of the characteristics that do allow support for life today is created by life itself - like free oxygen. And looking back through geological history one can see that Earth has had great variations in temperature and oxygen content.
As for how it is on other planets - they may have life, but it may not be life as we recognize it here - it can be all the way from mostly silicon based algae to advanced life that can be compared to humans but with a completely different cultural aspect that considers us humans as inferior or more like ants - a great object of study but nothing worth talking to.
If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.
I suspect it's significantly LESS than one per galaxy, so that when life does arise it's almost certainly all alone in its home galaxy.
For that matter, most of the things in their list are very odd things to choose for a "Rare Earth" argument. Gas giants in the outer solar system- there's no reason to assume that they're rare. Plate tectonics are believed to be a symptom of planet size (so larger-than-Earth rocky planets should have it), and several of Jupiter's moons show tectonic-style surface patterns. A magnetic core- ditto to planet size (where a solid core needs to be formed by pressure), with a possible proviso on planet age and planet chemical composition (influencing how long the core would take to cool). As there are only two Earth-sized planets in the Solar system, it's almost impossible to draw conclusions about frequency of occurrence.
The Moon is just about the only item in that list which I can agree with as being "rare", and as you say, its influence is debatable.
The better answer is to say that we don't know... because the likelihood of extraterrestrial intelligence that is typically used is only extrapolated mathematically from the information that we have. But because of the size of the data set that we have relative to the actual size of the cosmos, the probability for error in that regard is, by my understanding, roughly equivalent to anticipating the results of a random coin toss.
Simply put... we just don't know. And that's a *FAR* more truthful answer than "no"... or "yes", for that matter.
As things currently sit, based on our understanding of the universe, we might as well be the only intelligent beings in the whole cosmos, and so the answer might as well be no, even if such an answer turns out to be false. But if that actually were the case, and we were unique, then nothing would have any real reason to change. For some, such uniqueness might even be a compelling reason to believe in a god, but it is hardly irrefutable proof of even that.
The way things currently sit, based on all the evidence that we have accumulated so far, and without any mathematical extrapolation, Earth does, indeed, appear to be special... We have not found any other worlds like it to date. And while our inability to do so might only be because of the limitations on extrasolar planet detection technology, that limitation is hardly remotely conclusive proof that such undetected earth-like planets actually do exist.
File under 'M' for 'Manic ranting'
There is actually no need to refer to the Yule Tide as christmas. Christians co-opted the holiday recently and atheists should just insist on the older term.
Excuse me, but please get off my Pennisetum Clandestinum, eh!
Why can't life evolve inside a star?
Asimov (a biochemist) wrote a short story about an alien civilization in our own sun, where one of its interstellar ships crashes into the earth; these creatures had no concept of "planets".
I wish I could remember the name of the story.
Free Martian Whores!
"In a sufficiently large (possibly infinite) universe, it really just doesn't matter how uncommon any (non-zero) probability event appears - It will still happen all over the place, over and over and over and over again."
This is based on mathematical extrapolation, and while provably true for an average event. The proof cannot be verified all events without utilizing parallel universes.
But uniqueness would not in *ANY* way constitute any sort of proof of the existence of a god or verifying a creationists point of view, even though some might think that it would.
Suppose for a moment that it were actually possible to discover that we were isolated in the cosmos... that we were "it", and that intelligent life was otherwise non-existent anywhere else. While that might seem to mean something to people, in the grand scheme of things, it really doesn't mean anything at all... any more than the fact that a lot of people think that the northern lights are pretty means something particularly profound and meaningful about the meaning of life or whatnot. The cosmos can exist entirely without any purpose or meaning to it at all, and our human nature to ask "why" would only be destined to remain perpetually unanswered. This is equally true whether we are unique or not.
File under 'M' for 'Manic ranting'
You need fidelity, actually. Monogamy is not required.
"Who is the Journal of Quantum Physics going to believe?" --Stephen Hawking
The whole point of the Fermi paradox is that if the earth isn't special, then where the hell is the evidence of alien life? All these posts explaining how we aren't special, and how "life will find a way", just lead right back to it. Why haven't we found so much as a single piece of evidence of any kind?
Probably because the lifespan of technological civilizations isn't that long. Human civilization is about 3000 years old, but only about two centuries of that is technological civilization with enough power to do much. We've had the ability to send radio signals into space for less than a century. We're already starting to run out of natural resources. There are arguments over how many decades are left for some resources, but nobody sees many centuries of resources left. Trying to mine low-density resources requires greater energy inputs for the results obtained, and eventually that stalls out.
If our understanding of physics is roughly correct, fast interstellar travel is hopeless. Slow interstellar travel might be possible, but it currently looks like the closest interesting place is about 500 light years away. Sending a generation ship to a system with no habitable planets is pointless. Sending one to an active civilization means it gets there after they've run down.
If you plug reasonable values for extrasolar planets into the Drake equation and set the lifespan of a technological civilization to 500 years, you get 24 civilizations currently active in the Milky Way galaxy, which is about 100,000 years across.
Climate fluctuations may actually be *beneficial* to the rise of life. There is speculation that a "snowball earth" scenario played an important role here.
Sheesh, evil *and* a jerk. -- Jade
Climate schlimate. Must be the branch of science with most false predictions by far.
Yeah, they consistently underestimate how fast climate is changing.
Why should anyone believe these climate theories when they cannot accurately predict even next week's weather?
A ten-year-old can accurately predict that next winter will be colder than next summer.
Predicting the big picture tends to be a lot easier than predicting the little details.
Sheesh, evil *and* a jerk. -- Jade
Weather is not climate.
2/10 for effort.
The Moon is just about the only item in that list which I can agree with as being "rare", and as you say, its influence is debatable.
For life to evolve, requires a changing environment. Without the moon's tidal effects, there would be a lot less dynamic events happening on the Earth. (I agree there still would be a magnetic field and plate tectonics; however, perhaps both of those were a result of the collision of pre-Earth and Theia which created the moon.)
Additionally, one effect the moon had when it was closer (it's moving away at a rate of 1.5 inches per year, we know thanks to the reflectors placed there in the 60s which scientists are bouncing a laser off, daily, since then) was that it sloshed the oceans around a lot more.
That sloshing brought nutrients from the land into the ocean (accounting for the salty taste), and allowed those nutrients to slam into each other, combining in different ways that ultimately led to life. As the moon receded, the sloshing was reduced, allowing the life that had evolved to better survive.
If I was to speculate, I would actually speculate the opposite of what I quoted above: I would imagine that every world that has evolved life has a moon.
I feel fantastic, and I'm still alive.
I'd bash stamp collectors as well if they actively worked to block the teaching of science in schools, denied funding for legitimate scientific research, and pushed their viewpoint through taxpayer funded faith-based initiatives.
Stamp collectors actually help subsidize the US mail since they boost profits with minimal cost to the post office. What's not to like about them?
"We make our world significant by the courage of our questions and by the depth of our answers." Carl Sagan
Aliens don't stop because they are busy searching for INTELLIGENT life.
Dear Aliens,
Don't be racist, Thank you.
The People of Earth.
P.S. Do as we say, not as we do.
Why did the human cross the road?
Because he's still stuck on his planet and can't fly.
A human walks into a bar with some Uropian gas termite his shoulder. The bartender before he throws them out asks, "Where did you get that disgusting thing?"
The gas termite says "On planet Water, these dumb fucks are everywhere."
Do you remember in High School the retarded kids and their classrooms? Did you ever go in them? Did you know the retarded kids? Don't feel bad, nobody did. You knew where they were though so God forbid you stumble anywhere near there and be mistaken for a retard. If retards spoke, you just ignored them. Well I hate to tell everyone, but Earth is the Retard Class of the Galaxy. There are plenty of Aliens out there that know damn well where we are. But do you see them coming here? They don't want any of that "retard" rubbing off on them. Oh sure, we get sightings and such, but nothing official. Do you know why? These are the Aliens that are throwing spitballs at us and calling us RETARDS and running the hell off before they end up in detention or suspended.
"Why?" do you ask????
Well imagine our Alien benefactors who waited breathlessly and patiently for us to come out to space and prove we are intelligent. Who do we send? A dog! Imagine that? So they do a mind probe to find out WTF it wants and it wants a bone. They consider the situation and just leave and chock us all up for being retarded.Word gets around you know. Yeah...that new planet..? It's retarded!
So you ask me, is Earth special? I say yeah, it's special alright, it's Special Ed.
Take the Red Pill.