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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.
What a load of crap. I love when they go with old data. A recent study how's that the moons effect over our planets stability is marginal and that, though there would be changes it would not be 'detrimental to life'.
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
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.
"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!
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!!
A few minutes to a few hours start life, 9 months for it to take hold, and a few seconds to end it. That's human mortality in a nutshell.
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.
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!
"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'
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.
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