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No Moon Needed For Extraterrestrial Life
sciencehabit writes "Given the generally accepted idea of how Earth got its big moon — through a dramatic collision with a Mars-sized body that knocked a huge chunk of Earth loose — astronomers estimate that only 1% of all Earth-like planets in the universe might actually have such a hefty companion. That would mean planets harboring complex life might be relatively rare. But researchers have now carried out large numbers of detailed numerical simulations of 'moon-less Earths,' which show that the consequences are less dire than is generally assumed. According to the simulations, these planets would have ample time for advanced land life to evolve. As a result, the number of Earth-like extrasolar planets suitable for harboring advanced life could be 10 times higher than has been assumed until now."
YAY! We can be safe from Werewolves on these 'that's no moon' planets.
Also, "10 times higher" did they just pluck that number out of thin air?
I've seen several articles now about how much water is in the center of the moon, calling in to question this theory about the origin of the moon. I've never liked this origin theory, anyway. The large gravity well of a bigger object pulled in a smaller object. Boom, easy stuff. And how in the universe can someone talk about how unlikely it is that other planets would have moons, when our own solar system has several planets with moons? A quick google search reveals this image: http://upload.wikimedia.org/wikipedia/commons/thumb/4/4f/Moons_of_solar_system_v7.jpg/800px-Moons_of_solar_system_v7.jpg
Don't tides and seismic activity play big roles in how we think life evolved?
no more or less idiotic than this bias-driven modeling of speculation based on assumption which has no bearing whatsoever on reality.
It's only idiotic if you demand that it be accurate, if you use it as a framing of the discussion, it is a nice place to start.
Nerd rage is the funniest rage.
Why was there ever an assumption that a moon is required for complex life? Stabilization of the axis and climate regions? Or did we just assume it because it worked here?
Developers: We can use your help.
What model and what speculation?
And that idiotic fake formula so many like takes another hit.
I assume you're talking about the probability of life emerging? I don't see how any such estimate is beneficial. For all we know we could be completely alone or the universe could be teaming with little green men.
But if you're referring to what I think you are, based on the scale of the formula, a single order of magnitude really wouldn't make much difference.
The Daddy casts sleep on the Baby. The Baby resists!
They're saying that the moon stabilizes the axial tilt wobble, so the climate doesn't change drastically (over loooong periods of time), so therefore life would have time to evolve, which is an interesting notion. However, I thought it was generally accepted that the moon's tidal effect on the oceans (literally "the tides") was one of the big contributors to the emergence of life. Seems they're hand-waving that part.
And that idiotic fake formula so many like takes another hit.
What? Sounds like you need to take another hit.
Calling that event dramatic would be like calling cannibalism inconvenient.
Why would a moon the size of ours be a requirement? That never made sense to me.
..
Kind of helps to have an active geodynamo and the resulting magnetosphere though
I'm not an astrophysicist, so I'm a bit behind here, but how could the earth have collided with a Mars-sized object? Wouldn't it have caused the orbit to be much more eccentric than it is now?
"First they came for the slanderers and i said nothing."
Here's what a rational, realistic analysis of tech progression would expect. GIVEN that life on earth can self replicate itself and use a huge range of molecules for fuel, it seems obvious that more sophisticated life is possible than already exists. Our star exhausts enormous amounts of free energy into space every second. Thus, one would expect that some day, perhaps next century or thousands of years from now, we will develop more sophisticated life that can use ALL of the matter in our solar system (rather than just a narrow range in the biosphere) and will use solar energy to rapidly convert all matter into parts of this life. This expectation is known as the singularity, and generally is assumed to require both artificial intelligence and molecular manufacturing (nanotechnology) to take place. There are plausible reasons to think that this event might happen in this century.
Well, if this is GOING to happen, and one would expect other intelligent life to do the same, and to eventually reach the same point. Then why don't we see the evidence of this out in space? Most of the stars should be missing, radiating mostly in the infrared. There should be a cacophony of data transmission between stars, although we might not be able to detect this. There should be other evidence of lively interstellar civilizations.
Theories :
1. The singularity is not physically possible. That means, of course, that our theories of physics are massively wrong as well, and that all our assumptions about intelligent life are as well.
2. Every single intelligent civilization self destructs. This also seems ludicrous...even if it happens some times, there should at least be remnants.
3. We are the first within our region of space. It took life on this planet ~3 billion years to get to this point, and many billions of years for this planet to form with the elements it has. The universe is only ~13 billion years old. Possible...
4. Technology can do even more than we assume. Maybe you don't actually need to surround stars with solar collectors to get energy...And our neighbors obey the prime directive...
And so forth. The number of possible theories is infinite, the number of probable theories large.
'There would be more then enough time' presumes you know what conditions are necessary for that time to start counting, Just because life started on earth at a specific time, does not mean every planet would have that event happen , if it ever, at the same point in planetary time line as it did on earth. there is no way to know if 'enough' would be normal when you can't explain IF little lone WHEN there is a start.
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We have no fucking clue what it takes to support life as we know it, and we won't until we fully understand life and the process of abiogenesis. We do know a lot about where life cannot survive though, e.g. no oxygen, no water, etc. These equations are pretty much arbitrary.
There is a fine line between being a cultivated citizen and being someone else's crop. - A. J. Patrick Liszkie
In other words "We really have no idea what the chances are that life could evolve elsewhere. Nor what that life could be."
It seems to me like one of the factors that is essential for complex life to evolve is the presence of a magnetic field, in order to protect life (and a thin atmosphere) from the harmful effects of the sun. While we're at it with the search for extraterrestrial life - shouldn't the presence of a magnetic field be one of the "must have"s? I've always been under the impression that the large moon is what keeps the Earth's core churning and thus the magnetic field - but maybe that's less fact and more something that I came to believe on my own.
On all of your points.
According to TFA we did assume based on some calculations from 1993 that "Without the moon, gravitational perturbations from other planets...would greatly disturb Earthâ(TM)s axial tilt".
And as with all other assumptions we ever made on extraterrestrial life - if it worked here...
There IS though, another point in the "moon equation" that is only hinted at in the article. Possibly cause it is assumed to be taken for granted (more of the "if it worked here...").
That would leave ample time for advanced land life to evolve under relatively stable climatic conditionsâ"although what would happen to such life during an axial shift remains unclear.
If you want your sea-dwelling life to migrate to land, stable yet powerful tides that regularly wash the aforementioned sea-dwelling life ashore surely are a plus.
For plants and for animals that would feed on them.
Mit der Dummheit kämpfen Götter selbst vergebens
This is just a computer simulation regarding the stabilization of the axial tilt. It doesn't take into account other contributions the moon would have on the development of life. Tidal forces, both with the ocean and the liquid mantle, are believed to have had a major contribution to the formation of life.
the silly pointless simulations of the article, based on nothing but speculation and assumption and data gathering with a sample size of zero
Yes the probability formula. Factors that cannot be known.
the title should be No Moon Needed For Extraterrestrial Life In Computer Simulation
they fail to account for a lot of factors in which the moon plays a vital role.
Anons need not reply. Questions end with a question mark.
Yes, given that there was no real reason to believe that a large moon is necessary for complex life to exist. A look at the rotational axes of planets in the solar system indicates that they are more stable than would be expected with the naive moon-no-moon estimate. The only reasonable way that would happen is if other tidal torques are large enough to add stability. But given that it took nearly 4 billion years for complex life to arise here, it's probably fairly rare even if conditions would allow it to develop.
But the Drake equation is meant only to estimate the number of possible civilizations, not to be an exact calculation. There is nothing "fake" about it. When I plug in numbers I get that there is no reason there couldn't be 750,000 civilizations in our galaxy. It's also quite possible that there may only be 1 civilization per 20 million galaxies. There's a lot more certainty in some of the parameters, so I should recalculate, but that low end estimate probably won't get much larger.
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That's all very nice. When the scientist have found a representative number of worlds - what shall we say; 10? an even dozen? moonless, life-containing worlds, then they'll have a theory worth considering. Until then, they've got nothing.
politicians are like babies' nappies: they should both be changed regularly and for the same reasons
Who ever said that a moon was REQUIRED for life to exist?
fecking morons
than just stabilize the tilt. While I'll have to wait till some real astrophysicists to analyze the implications of this, I know that much off the top of my head.
The Drake equation:
R* = the average rate of star formation per year in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fl = the fraction of the above that actually go on to develop life at some point
fi = the fraction of the above that actually go on to develop intelligent life
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space.[3]
So, with fl,fi,fc and L (4 of 7) being completely unknowable, the result N is something more than parlor talk? No.
I'm all for parlor talk and will ponder extraterrestrial life with anyone. My personal opinion is there is other intelligent life, it's just really friggin' far away.
Make a percentage estimate? Pfffft! It's bullshit.
Ah, so you know every planet in the universe?
Yes, but the universe is a large place. It's like the fact that you are extremely unlikely to win the lottery, yet almost every week someone wins. And yes, a planet getting life is much less probable than winning the lottery, but then, there are many more planets in the universe than lottery players for a given lottery.
No. It only proofs that there's no intelligent species which had the chance to reach us. It doesn't preclude non-intelligent life on other planets (maybe it's a highly unlikely event that intelligence evolves on planets with life), nor does it preclude intelligent life anywhere where it couldn't have reached us (I think even Andromeda is far enough that an intelligent species would have had no chance to visit us or send robots; anyway, an intelligent species 10 billion light years from here definitely wouldn't have come here.
And even for intelligent life in our galaxy, it's not a disproof of intelligent life; it just makes it more unlikely. Imagine there are exactly two intelligent species evolving in our galaxy. Then there's a 50% chance that they are behind us. And since we ourselves didn't ever get to a planet of another star, it's no surprise that they didn't come here anyway. Even three intelligent species would not make it too improbable that we are the first.
Moreover, it's not a given that any intelligent species will do space exploration beyond their solar system. Indeed, it might be that most just don't survive long enough.
The Tao of math: The numbers you can count are not the real numbers.
Oh. Seems like we agree.
I like astrobiology, I may even end up working on something in the field. However, i would still mod you insightful if i had the mod points.
Sample size of zero indeed. Well one could say it is one. However in statistics this is still the same thing thereabouts.
The Grey Goo disaster happened 3 billion years ago. This rock is covered in self replicating machines!
You really don't understand the law of large numbers, do you? Yes, the chances are vanishingly small, but the number of solar systems is exceedingly large. Multiple the two together and you will still get a very, very large number.
Isn't it interesting that the Earth is situated on the inner edge of the arm of our galaxy? Close enough to stay within the Galaxy's gravity well and prevent being thrown out into the void, but not so close that we're going to get sucked into the core. We're nowhere near any black holes, or extreme gravitational tides that would tear our solar system apart. We're well over 600 light years away from any giant or supergiant stars so we're outside the range of supernovae. We're not near the galactic core either, so we're not getting burned to a crisp by extra-solar radiation.
Then we've got Jupiter conveniently positioned in the mid-to-outer reaches of our solar system to sweep away comets and asteroids, not to mention Saturn, Uranus, and Neptune. Our sun is a medium orange star and probably one of the most stable configurations out there as far as stars go. We're at a convenient range away from the sun, plus we're on a planet that has an active core and thus can generate a magnetic field to protect us from the solar wind. And then, there's the Moon - a abnormally-sized piece of extraordinarily round rock that happens to be in a stable orbit around our planet.
Given all the possibilities and probabilities out there, I feel there's a legitimate case for saying we fail the Copernicus test, and that there's more than just coincidence to our existence here.
Here's to hot beer, cold women, and Glaswegian kisses for all.
And, pray tell, what values do you plug in when you haven't a clue? Say, fl, fi, fc and L?
"So what you're saying, Percy, is that some number you've never calculated might be ten times larger than some other number you've never calculated."
Koans and fables for the software engineer
"...astronomers estimate that only 1% of all Earth-like planets in the universe might actually have such a hefty companion"
"As a result, the number of Earth-like extrasolar planets suitable for harboring advanced life could be 10 times higher than has been assumed until now"
If Earth-like planet with moons represents 1% of of all Earth-like planets. Now that we can take all Earth-like planet, so changes are 100 times higher, not 10.
"Given the generally accepted idea of how Earth got its big moon"... the exact manner in which we got our moon doesn't really have much bearing on whether or not a moon is needed for the development of life, although it may "impact" the continued existence of any life already present. Every planet further out than Earth has more moons than us (totaling 139 so far, http://www.spacetoday.org/SolSys/Moons/MoonsSolSys.html ) , and I can say with reasonable certainty that the moons of the gas planets were not created by collisions between those planets and unnamed impactors.
Well, most of it is guesswork but it's becoming less and less guesswork. Take for example the number of planets. 20 years ago we didn't have a single confirmed extrasolar planet, now we're gathering statistics on them. True, we don't know what "habitable" is but we're approaching it from both angles:
1) We're trying to determine just how "earth-like" a planet is - this is a never ending story of orbit, mass, composition, satellites and whatnot getting closer and closer
2) We're trying to determine just how flexible life is looking at our extremophiles, how different can a planet be from earth and still be habitable.
Maybe there's life that's weirder than we can imagine, but these are just boundaries and if they cross, if we find planets that are so earth-like the life we *do* know could exist on them that would be a huge step. We are working on abiogenesis, with enough time we may discover exactly what conditions are necessary for life to begin, that is how tight the needle eye is. I doubt we could ever properly simulate life as such, but if we could show that primitive life would move towards more modern single-celled life I think the essence of evolution into more advanced life would follow.
By far the hardest to ever say if intelligent life like humans would ever evolve - I mean most species on earth do well and thrive without being that intelligent and have done for millions of years. Humanity almost went extinct 1.2 million years ago, we're rather crappy animals without tools, not being particularly strong or fast, no hide, no fur, no claws or teeth to scare anyone and our newborn defenseless. It takes a lot of energy to run our big brains, our evolutionary success was far from certain - it just seems so in retrospect as the tools have so far greater potential than even the toughest animal.
Live today, because you never know what tomorrow brings
Drats! Foiled again!
You just blabbed out the perfect formula for story submission on /.!
We'd have kept it secret but for you meddling kids!!
Sig Follows: "Suppose you were an idiot. And suppose you were a member of Congress. But I repeat myself." -- Mark Twain
That is just keep making it worse.
"Well, most of it is guesswork but it's becoming less and less guesswork."
Only for R, fp and ne; with ne being dubious, as we have only one planet's experience with what can constitute life and we've not found all the variants here.
The problem with calling this a real equation (aside from the format) is the use of the word "actually". We have to either; 1 - find and catalog intelligent life or, 2 - be around long enough and have investigated heavily enough to reasonably determine there aren't any.
Even if we found the exact values for those three tomorrow, the formula would remain useless because we can't even answer the binary question implied in fl, much less fi. We can't even judge L because we haven't stopped yet.
You're forgetting the Bs factor:
http://xkcd.com/384/
And how many of those civilizations in our galaxy are close enough that we actually have a decent chance of picking up on their communications ?
Unless somebody is aiming a high power directional antenna right at the earth, the signal is going to drown in background noise very quickly.
So, let's start with facts and then extrapolate.
Number of planets confirmed to have life? 1.
Number of star systems confirmed to have life? 1.
Number of galaxies confirmed to have life? 1.
Alright, I've done the hard work. I'll let the rest of y'all get on with the figuring and equationizing.
I drank what? -- Socrates
The Mandark equation:
R* = the average rate of Clubs in our galaxy
fp = the fraction of those Clubs that have Fat Chicks
ne = the average number of Fat Chicks that can potentially be lured to your car with a twinkie (Or âoemoonpieâ if youâ(TM)re from the south)
fl = the fraction of the above that actually fit in your car without busting the suspension
fi = the fraction of the above that you can get home without your room mate/friends seeing them
fc = the probability of nailing said Fat Chick without her wandering off in search of the nearest IHOP/Dennyâ(TM)s/Waffle House in a sugar-induced trance
L = the length of time for which you can bang her without room mate/friends finding out
Any number > 0 is too scary to contemplate, tbh
Sig Follows: "Suppose you were an idiot. And suppose you were a member of Congress. But I repeat myself." -- Mark Twain
I would love a job where I could just sit on my ass and speculate all day.
Why do we keep assuming that life, even complex life had to be created in a habitat like our own. Hell even the variation of organisms here on earth show that life can exist and thrive in hostile places. Hostile to us at least. We need to stop thinking that just because WE are here then all other life will follow the same path. We are the product of our environment not the other way around. All these little "perfections" in the balance of life on earth are due to us evolving for billions of years and adapting to them. What might be right for you, might not be right for some.
Something between zero and one.
You're making quite the assumption that those factors are "completely unknowable". Perhaps in the literal sense that we'll never know them to the last decimal place until we've examined every planet in the galaxy, but we can come up with reasonable guesses by observation.
The best current value we have for fl depends on what you consider the value of ne for this solar system. It (ne) is at least one. It may be two or even three or four depending on how you feel about Mars, Europa and some of the other large moons "potentially supporting life". Let's call it two for the solar system, which gives us an fl of at least 0.5 for the solar system, possibly 1.0 if we find life (or evidence of extinct life) on Mars.
A value for fi is more interesting -- and much lower. Of course it depends on how you define "intelligent" (That's going to interact with the value for fc -- if you define intelligent as having technology, then fc nears unity, and fi will be low; if you define it as somewhat smarter than a plant, then fc drops but fi rises.) A more meaningful version of the Drake equation might break fi down into fe (fraction of live that evolves to eucaryotic-equivalent life) and then fi is the fraction of that which develops intelligence. Why? Because with astronomical instruments we could build today, we can start coming up with numbers for fl and fe by doing sky surveys and analyzing exoplanetary atmospheres. (Heck, if the numbers are high enough for fc, with "detectable signs of their existence" being something like industrial pollutants in the atmosphere rather than them beaming radio signals, we might even detect those. That definition also effects the value of L -- for Earth L is a couple of hundred years so-far by the industrial pollutant measure, only seventy or less years by the radio signal criterion.)
Sure, the numbers are difficult to pin down, and they'll be approximations. But that's not the same thing as "completely unknowable". Heck, we already know their aggregate upper bounds by virtue of the fact that the radio spectrum isn't jammed by signals from outer space.
The very fact that the Drake equation got you to discuss its particulars in detail is evidence that it is not entirely useless.
"through a dramatic collision with a Mars-sized body that knocked a huge chunk of Earth loose"
So where is the hole on the earth that the moon supposedly created, hmm?
Yep. Citing xkcd indeed introduces massive amounts of bullshit into the discussion. Basement dwelling dorks like Munroe don't seem to get that the Drake equation is not for actually calculating something, but a summation of identified parameters needed for the emergence of life. You gotta define the framework before you can work on the actual details. But hey, fapping off to your own perceived wit is so much easier, and that seems to be all Munroe does lately. He used to be good - 3 years ago or something. These days, he just got his head so far up is ass that he can lick is own tonsils from down below.
Ubi solitudinem faciunt, pacem appellant.
The Drake equation:
So, with fl,fi,fc and L (4 of 7) being completely unknowable, the result N is something more than parlor talk? No.
My own opinion is that the most important unknown in the Drake Equation will turn out to be "fi" - the fraction of life-bearing planets on which intelligent life develops. I say this, because, on this planet, it took several billion years for that to occur - and it seems safe to say that it appears to have been a product of sheer random chance.
I suspect we will discover the approximate value of "fl" sometime in the next four or five decades (note I said "approximate value"), by employing space-based telescopes whose resolution will steadily improve, generation by generation, to the point that Hubble will eventually look like a toy by comparison.
I also suspect that "fc" will turn out to be something close to 100%, and L to be somewhere between 10,000 and 100,000 alien-civilization-year-equivalents (but only because the equation fails to distinguish between intelligent species and civilizations - which, IMnsHO, ain't the same animal at all).
But the biggie is definitely "fi". And, because it seems fairly safe to say that the development of civilization-capable intelligence is likely to be just as random an event elsewhere as it was here, I strongly suspect it will turn out to be a very low value, indeed.
I'm all for parlor talk and will ponder extraterrestrial life with anyone. My personal opinion is there is other intelligent life, it's just really friggin' far away.
If I'm right about the value of "fi", you're liable to be right, too. And I suspect you are.
Check out my novel.
We're making an assumption that because it worked this way here, it can work this way elsewhere and the likelihood of life arriving under other conditions is unknown at best, and probably rather difficult. We have no basis for this assumption. It's in fact, equally likely that life arriving on earth was an extremely rare occurrence and that in most other situations it could have arrived much much earlier. For all we know even the planets in our own solar system could be swimming with life and we just haven't seen it yet. The only planet we've even scratched the surface of is Mars and we've literally only scratched the surface of an exceedingly small area.
Because, the default position has been that life is exceedingly difficult to make happen, and that you needed a truck-load of favorable conditions to even hope it could happen. I think the notion was that we were a rare and unique solar system. ...
The more time passes, the more it's hard not to look at Drake's equation and figure that he might have been onto something
For any denominator in Drake's equation where we don't have the technology to measure it, shouldn't the null hypothesis be that Earth (and by extension us) is dull and ordinary?
Other assumptions just sound like the echos of geocentrism.
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OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
The problem is that we'll only be able to measure fl, fi, fc, and L by the time we know the answer (hell, we may be take a long time after we know the anwser just to discover L). By that sense those numbers are unknowable. By the way, at least for our galaxy we kow that the number of alien civilizations with interestelar travel capability that go into exponential growth (as everything alife seems to go) for up to a couple handred years ago is zero.
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No Moon, no tides, no critters.
Sorry, you critter lovers.
a twice-daily tide from a binary system like ours could have a significant influence on vertebrate development. I bet there's a lot of inverts out there awaiting discovery, but it's a lot harder to evolve critters the rest of us would find interesting.
Is it a rule, that there's an exception to every rule?
I have a few questions and perhaps one of the more enlightened slashdotters can help me out.
If the Earth was really hit with a Mars sized object that eventually became our moon, does that put the earth "behind" other earth like planets in the amount of time it would have taken the earth to restabilize and have the right conditions for life? In other words, if the Earth was never hit by the Mars sized object and conditions for life were still present, would the Earth have developed life millions if not billions of years sooner? So there is a chance could be millions of years behind other extraterrestrial civilizations.
My other question: If we assume the earth was hit by a Mars sized object, giving our oceans tides and our mantel stability, and if we also assume that the these factors speed up the evolutionary process, is it possible that we could be much more advanced than other alien civilizations?(assuming we all started at the same time). They could still be working on crawling out of the water.
Scary thought either way.
"To Err is Human To Forgive is Divine neither of which is Marine Corp Policy"-My SNCOIC
Tidal action certainly contributed to the evolution of aquatic creatures to land-based creatures, and without a large moon, tidal action is not as great. I didn't see this mentioned in the article. Am I overestimating lunar influence on tides?
Proverbs 21:19
First let me state that, to paraphrase an SMBC comic don't listen to people talking about something they are not an expert in.
Second, rarely do the "you can't have life/intelligent life because..." people have both a biology degree and an astrophysics degree. You need both to make those kind of comments.
Thirdly, we now just about jack-sh!t about the majority of the mass of the universe. Most mass is "dark matter", and of the stuff that isn't dark matter, most of it is in the objects we call black holes at the center of galaxies. So we have no freaking idea at all about whether the majority of the universe is capable of supporting life/friendly to it.
Fourth, to paraphrase a visually dramatic, but (aside from this quote), fairly innane movie "Life will find a way". The entire thing about life is that it adjusts ITSELF to the universe, not the other way around. We are a life form that likes 1 g, 1 atmosphere of pressure, etc. not because those conditions are helpful for life but instead because THAT is where we evolved. Yes, 100g and 100 atmosphere would be harder to create life in, evlove in, but at the same time, we cant survive in 4g, 10 atmospheres, but life can easily evolve to do so.
The best argument there is against intelligent life being wide spread is the lack of signs/contact. But that says nothing about unintelligent life, and assumes that life would use radio waves. It is as likely that other intelligent life forms are dark matter based - and never discovered radio - as it is for there to be no other intelligent life in the galaxy. Or simply that radio waves have disadvantages we don't know about. A quantum physics related random shifts in signal over long distances could obscure intelligent content, rendering radio waves indistinguishable from background radiation.
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You really don't understand the law of large numbers, do you? Yes, the chances are vanishingly small, but the number of solar systems is exceedingly large. Multiple the two together and you will still get a very, very large number.
Uh, do yo know the definition of insanity? Repeating the same action over and over again expecting a different result. Since there is not a single example of life outside of this planet, the chances are not small but rather unknown. You would have to have another data point other than Earth to even begin to speculate on the "chances" of extraterrestrial life. Large numbers have nothing to do with it. For example, Zero divided by any number regardless of size is still zero.
Jesus was a compassionate social conservative who called individuals to sin no more.
Sorry but the burden of proof is on your side, not the other side. You cannot provide any evidence of life on any other planet in our solar system let alone elsewhere. Anything else is just built on conjecture. You might as well call your belief in extraterrestrial life a matter of "faith". It is a faith that I do not share.
All available "evidence" points to the Earth being the only life bearing planet in the universe.
Jesus was a compassionate social conservative who called individuals to sin no more.
Intelligent life may evolve differently, for example the dominant lifeform might be 3 legged with 2 heads and its brain in its belly.
They are called upper limits and lower limits. Just because you don't know the value of a specific quantity, you can often place limits and in some cases determine the shape of the likelihood distribution for the value.
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Yes, but any civilization in the galaxy more than a few centuries beyond us (assuming our technological growth continues) will know that this star has an earth mass planet with both liquid and solid surface and a biosphere driven by oxygenic photosynthesis. We've been broadcasting that fact for half a billion years. If they were going the point a directional antenna at a planet and transmit a beacon, we'd be a very good choice.
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Vulcan has no moon.
Search as I may... I can not find a detailed paper on this study.
The study as only been presented at various conferences and short abstracts made available.
My understanding is that large impacts late in formation are probably common (it probably happen to venus but hit the other way and slowed its rotatation right down).
Had the Earth moon collision occur differently, the earth and Theia merged but the same angular momentum resulted. Then the earth would still be spining fast enough (less than 12 hrs) to have a stable non chaotic spin axis. Whats more the spin and compersition of the earths core would have still have resulted in a strong magnetic field shielding us from loss of water to space.
That said
How common are Earth-Moon planetary systems?
see http://arxiv.org/abs/1105.4616
And that is where al gebra comes from, so it must be valueless...or is that invaluable?
What comes out of a discussion depends on what you put into it. Al chemy, however comes from Egypt, once called Khem. It was originally used for beauty potions and poisons. So it's hard to judge the eventual value of something from where it starts.
I presume we're talking about the Drake formula. I don't trust it either, but this doesn't make it worthless. If you have a better formula to offer, you should publish it and argue for it's worth. Merely being snide is, indeed, worthless. It's even a waste of your time, unless your thing is having other people despise you. (Your kind, rather, as you choose to be anonymous. I congratulate you on your wisdom in that choice.)
I think we've pushed this "anyone can grow up to be president" thing too far.
I'm all for astrobiology, and there are many missions in progress and more planned to supply the field with hard facts and gain sample sizes.
But what we can measure is, itself, highly technology dependent. And not only on possible technology, but also on chosen technology. E.g.:
If we chose, instead of all these wars and military spending, we could put a pair of observatories in Neptunes orbit. (Not circling Neptune, but at the distance of Neptune from the sun.) Put them antipodal in their orbits, and make the orbits as nearly circular as feasible. And give each observatory a mirror 5 miles in diameter. (At that size you can use flat panes of mirror without problems.) This gives us enough light collecting area to see most major planets in the galaxy (say Mars size or better) only provided that they are within some approximation of the habitable area around a sun. (So that enough light is getting reflected.) Now you need a bunch of computers to analyze the data.
Note that what I proposed here isn't anything that we couldn't do with the current "defense" budget. The new technology required is at most minimal. It would need to be robotized, as we don't have the technology for a closed cycle ecology, and occasional repair missions would be needed. And it would be expensive. But if we chose we could do it without any technology that we don't either have or know clearly how to develop. Better technology would, of course, make it cheaper, but it isn't required. You just need to be willing to throw away expensive gadgetry that could easily be fixed if you could reach it. And, of course, engage in highly modular design.
I think we've pushed this "anyone can grow up to be president" thing too far.
Sorry about the bolding. Don't know what happened as I *wasn't* using html.
I think we've pushed this "anyone can grow up to be president" thing too far.
That's too strong a statement. Light speed may be a true barrier. And in any case exponential doesn't imply fast. I could be a growth rate of 2^1.00001/Millenia and still be exponential. Eventually that would be overwhelmingly fast, but not for a long time.
I think we've pushed this "anyone can grow up to be president" thing too far.
Actually there are several reasons to believe that a large moon is either necessary for the evolution of life, or greatly speeds it. Two occur off the top of my head:
1) The existence of lunar tides yields tide-pools, where aquatic life is given an opportunity to evolve into life that can temporarily live in air. This is as true for bacteria as it is for multicellular life. Beaches also provide this opportunity, but waves strand a much smaller number of entities in a much less consistent manner.
2) A moon stabilizes the orbital inclination of the planet. A planet without a moon is much more likely to do a gyroscopic tumble.
I'm sure that there are other reasons. That they aren't necessary is an interesting claim.
I think we've pushed this "anyone can grow up to be president" thing too far.
The large moon also helps keep up tectonic forces. When the volcanoes die life will follow shortly (in geological terms) thereafter (we're not actually big enough to hold our atmosphere, volcanoes provide a constant supply of new gasses).
Liberte, Egalite, Fraternite (TM)
What do you do when your neighbor seeks to expand and you just happened to dump all your military budget on a giant mirror in Neptune's orbit?
When I read about Kaiser Wilhelm's plans to invade US during WWI, the sensation was similar to reading War of the Worlds by H. G. Wells -- hair-raising terror.
While losing military budget after WW2 propelled both Germany and Japan to become economic superpowers, I wold prefer to hold on to it just a tad longer.
Even without the Moon, the Sun would give us measurable tides. Even now there is quite a difference between tides when the Moon is half full or 90 degrees from a line from the Sun and tides when the Moon is new or Full or inline with the Sun.
One thing is I understand the tides were very extreme early in the Earths history, perhaps measured in miles. This may have really pushed evolution.
https://en.wikipedia.org/wiki/Inverted_totalitarianism
True, but it doesn't say anything about intelligent or complex life.
... is that a moon is required.
Back in 1985 I've done some "artificial evolution" simulations on a computer. What I learned is that if living conditions are good, then no evolution happens. It's when conditions are tough when evolution kicks in. But if conditions are "marginal" all the time, life will simply die out. What is needed are cycles. Good times are succeeded by bad times and vice versa.
And the good thing about earth is that we have lots and lots of cycles. Ripples on the oceans have a period of about 10Hz. Waves 1Hz to 0.1Hz. then there are cycles with higher and lower waves. Then there are the tides at every 12 hours. Then day-and-night at 24 hours. Then the moon at 28 days. Then seasons at once a year. Then the solar cycle at 11 years, and very likely the earth is also involved in larger cycles causing ice ages and things like that.
Life on earth with the dinosaurs and such was "stable". Nothing much changed. Only when a catastrophe hit, did things get moving again.
The evolutionary reason for this is that when a certain trait (gene) is 5% better for the individuals that carry it, the carriers will not overtake the whole population. Some percentage of the population will evolve to have the gene, but not all. This is essential for evolution: If this didn't happen, life would die out quickly. Some genes that carry an advantage have disadvantages as well. So a gene that helps individuals when it's rainy might prove fatal in a drought. So it is essential that the pool of genes remains large. Then when "bad times" arrive, some of the bad genes might prove fatal for the individuals carrying them. Population shrinks. Some lines will die out.
Once the good times are back, all remaining genes will multiply and a differently diverse population is ready for the next catastrophe.
In conclusion. No a moon is not necessary. However on earth it is responsible for two of our cycles that have pushed evolution forward. If a planet is to support life, it will have to have many cycles at many orders-of-magnitude, and if it doesn't have a moon it will most likely not have enough.
Life and no moon? Possible in theory, but very unlikely.
I have proven that the "proof" of the AC that we are "definitely" alone is no proof.
My position is that we simply don't know if there are other life forms. Since nobody disagrees that we don't have proof for extraterrestrial life, all I have to do to is to show that the alleged proofs against it don't hold. Which I just did.
No. Nor did I claim so. However I do know that there's life here on earth, and that means there's a non-zero probability of a planet developing life. It could be that this probability is so low that life only developed here. However we have no evidence that this is so, and our mere existence speaks against it (indeed, if I wouldn't support the many worlds interpretation of quantum mechanics, I'd say it's strong evidence because if life is so unlikely, the more likely event would have been for it to not develop at all anywhere in the universe; of course MWI tells us that if it could develop, there's a world which did develop it, no matter how unlikely it is, and it's obvious that we are in that world and not in another).
Yeah, like your conjecture that because I reject a flawed proof that extraterrestrial life doesn't exist, I must be convinced that extraterrestrial life does exist.
I don't believe in extraterrestrial life. But I also don't believe in the non-existence of extraterrestrial life. Both positions lack any evidence. And the position that there exists extraterrestrial life has actually good arguments, because after all, we know that life did develop on earth, therefore it's possible for life to develop in our universe. Claiming that life did develop only here means claiming the the earth is very special; so special indeed that there's no single other planet with the same properties in the whole universe. Which in itself is a quite extraordinary claim. One which only gets acceptable (but far from evident!) to me due to MWI.
tl;dr: If you accept MWI (as I do), the question of extraterrestrial life is strictly open. If you don't accept MWI, you have to accept extraterrestrial life.
The Tao of math: The numbers you can count are not the real numbers.
Did god tell you that? Lot of schizophrenic prophets on slashdot these days.
Value of your assumption, multtiplied by the zero is... well would you look at that, Zero!
What I don't get is why we're excluding gas giants that we're finding in the habitable zones. If Jupiter were where Earth is in our system, Callisto would be a great candidate. Ditto Saturn/Titan and Neptune/Triton. In fact, a gas giant in the goldilocks zones should offer more chances at a habitable body; the moon simply has to be far away enough not to be toasted by the planet's magnetosphere.
I'm sure the scientists are aware of this, but why has this eluded the journalists informing the general public?
I see what you did there. Global Warming denier!!!11111
I know that it's Slashdot and there is a joke about never reading the fucking article. But the site also has a "news for nerds" slogan, which rather implies that you'll be held to nerd standards of understanding and application, not the knuckle-dragging idiocies of the general population.
The fucking article exactly disagrees with this second point of yours.
Oh, you just want to go with your idee fixee prejudices, not actually learn anything new? Well, if that's the case, please do let the door hit you on the arse as you leave.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
That assumes that the light speed is a barrier, and that the exponential growth is something not as small, altought 1.0001/millenium would be enough (that's one less zero than your proposed ratio). Ok, there could be a slower civilization out there.
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Find me a white American who doesn't have a drop of nigger blood in him, and the question might be meaningful.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
Water is the important component to plate tectonics. Venus, which has no water, has no active volcanism or plate tectonics, yet has a significantly denser atmosphere than we do despite being about the same size.
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By "we" I meant the species, not any particular country.
Yes, I'll agree that governments (i.e., the people running them) are sufficiently untrustworthy and aggressive that doing this would be problematical. But that's a comment on the species, not on technological requirements.
Given our species this would probably be impossible until either a world government appeared or governments started being run by AIs...which *would* require a major technological & possibly scientific breakthrough. But existing species with vastly differing amounts of intraspecies exist, so there's no reason to believe that we are the least aggressive possible.
I think we've pushed this "anyone can grow up to be president" thing too far.
I think you didn't finish reading my post. It concluded with:
"I'm sure that there are other reasons. That they aren't necessary is an interesting claim."
I.e., I'm not saying they're wrong, I'm saying that isn't the answer I would have expected. (I'm not really convinced either way. And models aren't proof. But they can be very good arguments. And all we have suggesting that a large moon is necessary is also only good arguments.)
I think we've pushed this "anyone can grow up to be president" thing too far.
There are no tectonic plates, there are insane tectonic forces, including over a hundred volcanoes that make yellowstone look tiny in comparison.
Liberte, Egalite, Fraternite (TM)
My own opinion is that the most important unknown in the Drake Equation will turn out to be "fi" - the fraction of life-bearing planets on which intelligent life develops. I say this, because, on this planet, it took several billion years for that to occur - and it seems safe to say that it appears to have been a product of sheer random chance.
Yes, developing intelligent life needs enough randomness; but random changes that give surviving advantage are almost always kept by evolution, so it inevitably leads to intelligent life given enough time (it's one of the best ways to achieve survival).
My own opinion is that the most important unknown in the Drake Equation will turn out to be "fi" - the fraction of life-bearing planets on which intelligent life develops. I say this, because, on this planet, it took several billion years for that to occur - and it seems safe to say that it appears to have been a product of sheer random chance.
Yes, developing intelligent life needs enough randomness; but random changes that give surviving advantage are almost always kept by evolution, so it inevitably leads to intelligent life given enough time (it's one of the best ways to achieve survival).
I'm not at all convinced that evolution "inevitably" leads to intelligent life (and, more importantly, civilization-building intelligent life.) Randomness is ... well ... random, by definition. That, in turn, means language + tool-building capability can't be inevitable, because, unlike, say, rolling dice, with evolution, we're not talking about a limited set of outcomes. Instead, what happens is random mutation that may or may not have sufficient survival value that, under a given set of environmental conditions, a particular mutation gets disseminated sufficiently broadly to achieve at least localized dominance. And a relatively localized environmental phenomenon can end that process fairly easily. (Think volcanic eruption, epidemic, the appearance of a new predator, or the "one blue monkey" syndrome, for some instances, occurring soon enough after the mutation in question arises that the population it affects is small enough and geographically constrained enough to be completely wiped out.) It almost happened to humanity about 35,000 years ago, so it's not at all an unthinkable outcome.
And, remember, humanity's version of language + tool-building traits took several iterations and a number of mutations (upright posture to free the forelimbs to develop opposable thumbs, opposable thumbs themselves, plus a big brain with a highly developed frontal cortex to actually use those thumbs for tool building) to evolve an animal capable of developing civilization.
So, no, I don't regard intelligence as in any way an "inevitable" outcome of evolution.
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