The folly in using nature to predict the forms of sapient aliens

[KerikBalm]

Oh you're right I did the math assuming .1 percent of C. Haha!

Still, thats 300 km/s - the back of the envelope says it takes a mass ratio of 450 to 1, assuming Isp of 5 000s. With staging, most rockets can only achieve a mass ratio of about 20. To accelerate up to 300 km/s, this means you need an Isp of 10 000! Not impossible, but very difficult. Its unlikely that interstellar expansion can happen much faster than that.

Thats why I specified fusion power.

If you had something like a dense plasma focus, the exhaust velocity is easily high enoughto get you an ISP of over 100,000.

I should also note, that we are talking about reaching 30,000 km/s, not 300 km/s. 300,000 km/s is the speed of light... which of course you can't reach.

But for only 0.1C we can for the most part ignore the relativistic effects

Thrust would be pretty low, but for interstellar voyages, you've got time to accelerate.

What you want to look at is this (atomic rockets is an awesome site):

http://www.projectrho.com/public_html/rocket/supplement/dvNomogram01.pdf

0.1C is 30 Mm/s

Inertial confinement fusion, the maximum acheivable for that design as consdered (using D-T fuel I believe, if I remember the explanation correctly), leads to the 20:1 mass ratio.

A more advanced fusion reactor (way beyond what we have) that could fuse H-> He, would easily achive 0.1C -> requiring a mass ratio of less than 3:1...

But a reactor capable of the Proton-Proton chain or C-N-O cycles that take place in stars.... well such a thing is far beyond out capabilities, and perhaps would only be possible at all if built on an extremely massive scale (like a ship that makes a death star look small).

And a ship capable of performing the H->Fe sequence of fusion reactions... Well that thing could acheive obscene speeds... but if they were content with only 0.1C, then we're looking at a mass ratio of less than 1.75....

And of course, another option is to have the reactor at home, and synthesize antimatter, and pack that on to the ship...

Mass ratio needed for such a ship to reach 0.1C -> Less than 1.5...

To go 0.3C... its mass ratio still comes in at less than 3, and such a ship would cross the galaxy in less than 350,000 years.

0.35 million years to cross the galaxy, 3780 million years that life has been on Earth.

In the grand scheme of things... colonizing the entire galaxy can happen very fast once a civilization can make very good fusion reactors, or produce and store large quantities of antimatter

I disagree. Looking at history of our civilization you can say there were points where some things become obvious.

Gathering and hunting is no longer our main source of food, so we can spend more time on different things - it was one of important points in history of our civilization.

Imagine world full of smartphones, but you have no time to text because you didn't found diner yet

Developing of writings, math and education, so we can communicate and share knowledge. Today those things are obvious, but even 200 years ago?

Why would you teach math a slave that has only one job... picking cotton... I mean picking cotton faster.

That argument makes pretty much no sense to me, seems like non sequiturs to me...

care to try again?

What does most of humanity not adopting agriculture have to do with every alien species adopting a benevolent non-colonization approach?

Agriculture triumphed over hunter gathering because it was more efficient, and aided population expansion.

The exact opposite would be true for alien civilizations that decide not to expand.

Those that chose not to will be overwhelmed by those that chose to.

Edited April 12, 2015 by KerikBalm

[Technical Ben]

With 2 sextillion inhabitable planets in the observable universe, you'd be better off selling ocean-front property on the moon than you would be convincing a rational brain that life only exists here.

Large numbers do not an automobile make. There are a billion acres of land on Mars, but no carparks.

[Kibble]

well such a thing is far beyond out capabilities

Every rocket engine you mentioned is far beyond our capabilities. We don't even know if they're possible, and if they can even reach the ridiculous quoted efficiencies.

[-Velocity-]

There are tons of reasons why aliens might have existed for billions of years in our galaxy, and not colonized everything. The argument that Earth is not colonized so aliens don't exist in our galaxy assumes a very specific alien behavior- out of control colonization far beyond what is needed for certain survival. I was going to write a long rebuttal of this idea, but coincidentally, someone put this on io9-

http://io9.com/beyond-fermi-s-paradox-ii-questioning-the-hart-tiple-1697244447

The entire article is text so I'll paste it here:

Beyond “Fermi’s Paradox†II: Questioning the Hart-Tipler Conjecture

It’s become a legend of the space age. The brilliant physicist Enrico Fermi, during a lunchtime conversation at Los Alamos National Laboratory in 1950, is supposed to have posed a conundrum for proponents of the existence of extraterrestrial civilizations:

If space traveling aliens exist, so the argument goes, they would spread through the galaxy, colonizing every habitable world. They should then have colonized Earth. They should be here, but because they aren’t, they must not exist.

Astronomer Michael Hart, and cosmologist Frank Tipler propose that extraterrestrials would colonize every available planet. Since they aren’t here, they have proposed that extraterrestrials don’t exist. Carl Sagan was able to imagine a broader range of possibilities. Credit: NASA

This is the argument that has come to be known as “Fermi’s paradoxâ€Â. The problem is, as we saw in the first installment, Fermi never made it. As his surviving lunch companions recall (Fermi himself died of cancer just four years later, and never published anything on the topic of extraterrestrial intelligence), he simply raised a question, “Where is everybody?†to which there are many possible answers.

Fermi didn’t doubt that extraterrestrial civilizations might exist, but supposed that interstellar travel wasn’t feasible or that alien travelers had simply never found Earth in the vastness of the galaxy.

The argument claiming that extraterrestrials don’t exist was actually proposed by the astronomer Michael Hart, in a paper he published in 1975. Hart supposed that if an extraterrestrial civilization arose in the galaxy it would develop interstellar travel and launch colonizing expeditions to nearby stars. These colonies would, in turn, launch their own starships spreading a wave of colonization across the galaxy.

How long would the wave take to cross the galaxy? Assuming that the starships traveled at one tenth the speed of light and that no time was lost in building new ships upon arriving at the destination, the wave, Hart surmised, could cross the galaxy in 650,000 years.

Even allowing for a modicum of time for each colony to establish itself before building more ships, the galaxy could be crossed in two million years, a miniscule interval on a cosmic or evolutionary timescale. Hart asserted that because extraterrestrials aren’t already here on Earth, none exist in our galaxy.

Hart’s argument was extended by cosmologist Frank Tipler in 1980. Tipler supposed that alien colonists would be assisted by self-reproducing robots. His conclusion was announced in the title of his paper ‘Extraterrestrial intelligent beings do not exist’.

Why is it important that Hart’s argument wasn’t really also formulated by the eminent Enrico Fermi? Because Fermi’s name lends a credibility to the argument that it might not deserve. Supporters of the search for extraterrestrial intelligence (SETI) want to search for evidence that alien civilizations exist by using radio telescopes to listen for radio messages that extraterrestrials may have transmitted into space. Interstellar signaling is vastly cheaper than a starship, and is feasible with technology we have today.

Hart drew public policy consequences from his argument that extraterrestrials don’t exist. His paper concluded that “an extensive search for radio messages from other civilizations is probably a waste of time and moneyâ€Â.

Our political leaders heeded Hart’s advice. When Senator William Proxmire led the successful drive to kill funding for NASA’s fledgling SETI program in 1981, he used the Hart-Tipler argument. A second NASA SETI effort was scuttled by congress in 1993, and no public money has been allocated to the search for extraterrestrial radio signals ever since.

Just how convincing is the Hart-Tipler conjecture? Like Hart, Carl Sagan was an optimist about the prospects for interstellar travel, and Sagan published his analysis of the consequences of interstellar travel for extraterrestrial intelligence a whole decade earlier than Hart, in 1963. Sagan and his co-author, the Russian astronomer Iosef Shklovskii devoted a chapter to the topic in their 1966 classic Intelligent Life in the Universe.

Like Hart, Sagan concluded that “if colonization is the rule, then even one spacefaring civilization would rapidly spread, in a time much shorter than the age of the galaxy, throughout the Milky Way. There would be colonies of colonies of colonies…â€Â. So why didn’t Sagan, like Hart, assert that extraterrestrials don’t exist because they aren’t already here?

The answer is that Sagan, unlike Hart, considered unlimited colonization as only one of many possible ways that extraterrestrial spacefarers might act. He wrote that “habitable planets lacking technical civilizations will frequently be encountered by spacefaring civilizations. It is not clear what their response will be…Perhaps strict injunctions against colonization of populated but pre-technical planets are in effect in some Codex Galactica. But we are in no position to judge extraterrestrial ethics. Perhaps attempts are made to colonize every habitable planet…A whole spectrum of intermediate cases can also be imaginedâ€Â.

Besides assuming that interstellar travel is feasible, Hart’s argument is based on very specific and highly speculative ideas about how extraterrestrials must behave. He assumed that they would pursue a policy of unlimited expansion, that they would expand quickly, and that once their colonies were established, they would last for millions or even billions of years. If any of his speculations about how extraterrestrials will act aren’t right, then his argument that they don’t exist fails.

The evolutionary biologist Stephen Jay Gould was scathing in his criticism of Hart’s speculation. He wrote that â€ÂI must confess that I simply don’t know how to react to such arguments. I have enough trouble predicting the plans and reactions of the people closest to me. I am usually baffled by the thoughts and accomplishments of humans in different cultures. I’ll be damned if I can state with certainty what some extraterrestrial source of intelligence might doâ€Â.

In 1981, Sagan and planetary scientist William Newman published a response to Hart and Tipler. While Hart used a very simple mathematical argument, assuming that an alien civilization would spread almost as fast as its ships could travel, Newman and Sagan used a mathematical model like the ones that population biologists use to analyze the spread of animal populations to model interstellar colonization.

They concluded that the rates of expansion assumed by Hart are highly unrealistic. Expansion will be drastically slower, for example, if civilizations control their population growth rates on any given planet to avoid ecological collapse, if colonies have a finite life span, and if alien societies eventually outgrow expansionist tendencies. Hart’s assumption that an alien civilization would spread almost as fast as its ships can travel isn’t plausible. It’s possible to walk across Rome in a day, Newman and Sagan noted, but Rome wasn’t built in a day. It grew much more slowly.

If the evolution of intelligent life is at all likely, other civilizations could emerge before any hypothetical first wave of expansion swept slowly over the galaxy. If several worlds produced waves of colonization, they might encounter one another. What would happen then? Nobody knows. The history of the galaxy can’t be predicted from a few equations.

For Newman and Sagan, the absence of extraterrestrials on Earth doesn’t mean that they don’t exist elsewhere in the galaxy, or that they never launch starships. It just means that they don’t behave in the way Hart expected. They conclude that “except possibly in the very early history of the Galaxy, there are no very old galactic civilizations with a consistent policy of conquest of inhabited worlds; there is no Galactic Empire.â€Â

So, Enrico Fermi never did produce a powerful argument that extraterrestrial intelligence probably doesn’t exist. Neither did Michael Hart. The simple truth is that nobody knows whether or not extraterrestrials exist in the galaxy. If they do exist though, it’s possible that discovering their radio messages would give us the evidence we need. Then we could stop speculating and start learning something.

Anyway, to add to all that, I'd like to point out that if we ever survive long enough to establish interstellar travel, it's quite likely we'll have found a way to live sustainably on Earth. We will have conquered our drive to expand without limit. By the time interstellar travel is ever likely, we'll probably already have self-sustaining colonies on Mars, possibly the asteroids, maybe deep space. The need to expand to another solar system to ensure the survival of the human race will disappear. We have plenty of space and habitat right here in the Sol system. We could survive even past the death of the Sun, especially if we learned how to live in the Oort cloud.

If we do find aliens out there, and interstellar travel is possible, then what does it mean? It means that alien civilizations, at least the vast majority of them, do not expand without limit. It means that, codified or not, it is an expected behavior of intelligent beings to not expand too much, to give other alien life forms their space and a chance to evolve towards civilization. It could be very dangerous for us to start expanding without limit, aliens could rightfully see us as a threat to their existence and the existence and future diversity of life in the galaxy. They left our planet alone, and so we should be expected to return the favor. It is easy to see how this rule could naturally arise, even among beings who cannot communicate with each other, from the simple observation that while the opportunity to colonize existed, no one did it, and each different intelligent civilization (except for the first) owes its existence to that.

Edited April 13, 2015 by |Velocity|

[xcorps]

Looking at history of our civilization

Lets.

Earth's age 4.4 billion years

First appearance of life 3.8 billion years ago

First appearance of complex cells: 2 billion years

First appearance of multicellular life: 1 billion years

First appearance of animals: 500 million years

First appearance of primates: 60 million years

First appearance of humans: 2.5 million years

First appearance of modern humans: 250,000 years. This is 0.00006% of the timeline of Earth. Not really much of a history to talk about.

First launch of a human into space: 54 years. Humans have had the capability to travel into space for .0002% of their existence.

Number of times the Earth has experienced an event that extinguished more than 70% of extant species: 5

Someone smarter than me can calculate the odds that a life form capable of imagining travelling into space and then actually doing it here on Earth at it's inception. I'm willing to bet they are pretty astronomical (see what I did there?)

more advanced civilizations will try to hide from us until we get ability to travel between solar systems.

Could you provide a citation of proof please? This is mere speculation. It has as much value as quoting from a Robert Frost poem.

Reason is simple - you don't learn caveman about nukes and you don't give him your address.

Why not? What evidence do you have that "cavemen" are less intelligent than you are? Edited April 13, 2015 by xcorps

[Darnok]

Earth's age 4.4 billion years

Could you provide a citation of proof please? This is mere speculation. It has as much value as quoting from a Robert Frost poem.

As far as I know Earths age or answer for "how universe became what it is" are only hypothesis, lots of theories, speculations without clear proof?

Why not? What evidence do you have that "cavemen" are less intelligent than you are?

I think that "caveman" was more intelligent than most people is today, but that doesn't mean I would leave him my home address and teach him how to use gun.

I would observe and study, but won't try to contact him until he and his group would develop level of knowledge similar to my own.

Some people even today don't understand simple things, like at some point, if you got enough knowledge, you are no longer violent, you no longer want to steal or cheat.

Greed is something you dislike and you even disrespect greedy people and their actions. In my opinion in a similar way, the world is perceived by all highly developed beings.

Other thing is that knowledge gathered just from observing us may have more value that our planet and all its resources.

[xcorps]

A)Do you doubt the validity of radiometric dating or are you unaware of its existence?

why do you think "cavemen" were more intelligent?

C) what observations can you present that knowledge suppresses violence

D) other than star trek, what source do you have for the existence of a prime directive that you insist that a speculative species will follow?

[-Velocity-]

A)Do you doubt the validity of radiometric dating or are you unaware of its existence?

Small quibble- the Earth is 4.6 billion years old, not 4.4 billion

why do you think "cavemen" were more intelligent?

Well, Neanderthals DID have bigger brains. It's certainly possible they were more intelligent than us. It's also possible they were dumber. Brain size does not equate exactly to intelligence, and neither does brain to body ratio.

C) what observations can you present that knowledge suppresses violence

Well ignorant people do tend to be more violent, I would assume. This is because ignorance leads to poverty, and poverty leads to violence. Knowledge would thus suppress violence by allowing someone to have a good, productive job. But the true cause of the violence is poverty, not ignorance.

D) other than star trek, what source do you have for the existence of a prime directive that you insist that a speculative species will follow?

The fact that Earth is uncolonized by aliens despite there being tens of billions of potentially habitable planets in the galaxy where aliens could potentially evolve IS evidence of a real-life equivalent of Star Trek's "Prime Directive". It's only very weak evidence, however, as there are many other possible explanations- and combinations of explanations- that also result in an uncolonized Earth.

[RainDreamer]

Isn't it folly to use earth system for basis of any alien life form in the first place?

[xcorps]

Well ignorant people do tend to be more violent, I would assume. This is because ignorance leads to poverty, and poverty leads to violence. Knowledge would thus suppress violence by allowing someone to have a good, productive job. But the true cause of the violence is poverty, not ignorance.

Couple of things here:

A) correlation does not equal causation. The intentional homicide rate per 100k in the United States in 1901 was 1.2. In 1906 it was 3.9. Since then, it has varied considerably, peaking at 10+ in 1980. Are you suggesting that people in 1980 were 10 times more impoverished and more ignorant than people in 1901?

I challenge your claim that ignorance leads to poverty. If you were to suggest that poverty led to ignorance, I would agree.

The fact that Earth is uncolonized by aliens despite there being tens of billions of potentially habitable planets in the galaxy where aliens could potentially evolve IS evidence of a real-life equivalent of Star Trek's "Prime Directive". It's only very weak evidence, however, as there are many other possible explanations- and combinations of explanations- that also result in an uncolonized Earth.

So the Book of Matthew is evidence of the existence of Jesus, therefore the existence of God, therefore existence of Jonah, therefore proof that a man can be swallowed whole by a fish for three days, visit hell, and return.

We also have equally valid proof that a caveman named Fred excavated unknown minerals from the back of a sauropod.

[-Velocity-]

Couple of things here:

A) correlation does not equal causation. The intentional homicide rate per 100k in the United States in 1901 was 1.2. In 1906 it was 3.9. Since then, it has varied considerably, peaking at 10+ in 1980. Are you suggesting that people in 1980 were 10 times more impoverished and more ignorant than people in 1901?

I challenge your claim that ignorance leads to poverty. If you were to suggest that poverty led to ignorance, I would agree.

People who have an education make more money on average. Do you really not believe this well-known fact? I'm just saying, you can make a case that knowledge does in fact lead to less violence through the action of increasing an individual's investment in a well-functioning society. Furthermore, knowledge of and acceptance of human rights, the advancement of moral theory, HAS in fact lead to a reduction of violence world-wide. People watch the news and think we're living in a violent time, but it's not true. We're living in a golden age, which began to take off with the Enlightenment in the 17th century. Our golden age hasn't even peaked yet. I'd be afraid if it ever did, the Fall could be very unpleasant indeed.

So the Book of Matthew is evidence of the existence of Jesus, therefore the existence of God, therefore existence of Jonah, therefore proof that a man can be swallowed whole by a fish for three days, visit hell, and return.

We also have equally valid proof that a caveman named Fred excavated unknown minerals from the back of a sauropod.

So in your mind, very weak evidence == proof? Huh?!

You asked for any evidence that a "prime directive" actually exists, and so I gave you what you asked for. You didn't ask that the evidence support only the "Prime Directive" explanation

BTW, I was sorta teasing you, but I did find problems with all your statements

Edited April 13, 2015 by |Velocity|

[xcorps]

I'm just saying, you can make a case that knowledge does in fact lead to less violence

How many wars have been started by people who have little education? Wars are the ultimate expression of violence, and they are generally started by the political elite, who are generally well educated. Now, if you were saying CRIME and not violence (or violent crime perhaps), then we would be in agreement.

People watch the news and think we're living in a violent time, but it's not true

I think the society that we (you and I) live in prefers a peaceful resolution to a violent one, but I don't believe that the accumulation of knowledge is the reason for that.

And I gently refer you to the Mao Zedong Reforms, the Soviet terrors from 1917-1953, the atrocities in Congo under Leopold II, the Taiping Rebellion, the WWII genocide, the Armenian Genocide, the Rwandan Genocide...

You asked for any evidence that a "prime directive" actually exists, and so I gave you what you asked for. You didn't ask that the evidence support only the "Prime Directive" explanation

Lack of contact with extraterrestrial species is evidence of only 1 thing. We have not had any confirmed verified contact with an extraterrestrial species. All else is speculation without evidence.

BTW, I was sorta teasing you

Yes, my Fred Flintstone and Jonah in the whale response was tounge in cheek

Edited April 14, 2015 by xcorps

[KerikBalm]

Every rocket engine you mentioned is far beyond our capabilities. We don't even know if they're possible, and if they can even reach the ridiculous quoted efficiencies.

While H-> He or H-> Fe are far far beyond our capabilities, a D-D of D-T -> He reactor is not very far off, and would be sufficient.

It is quite clear that it is possible to make antimatter. H->He and H->Fe are also clearly "possible", but the question is if it can be done on a sub-stellar scale

Keep in mind that on the time scale we are talking about, a thousand years of development is "very close".

Then there's Bussard Ramjets to consider... granted its been shown they can't accelerate arbitrarily close to the speed of light... at some point the ramscoop thrust = drag (they would be good for decelerating though).

Even 0.01C would be more than enough time (10 million years) to colonize the galaxy, and such speed are actually clearly possible using fission power and Vasmir.

And then there's Orion drive's to consider... also clearly possible.

So.... anyway, the conclusion is that this galaxy is probably not populated by civilizations with spacetravel capabilities significantly more advanced than ours, that actually make use of such capability.

Its hard to believe they wouldn't make use of such a capability, so....

The conclusion is that this galaxy is probably not populated by civilizations with spacetravel capabilities significantly more advanced than ours.

Some people even today don't understand simple things, like at some point, if you got enough knowledge, you are no longer violent, you no longer want to steal or cheat.

Greed is something you dislike and you even disrespect greedy people and their actions. In my opinion in a similar way, the world is perceived by all highly developed beings

This is simply not true.

[Kibble]

and such speed are actually clearly possible using fission power and Vasmir.

VASIMR "only" reaches the efficiency of other electric thrusters, around 5000 seconds. Same for open-cycle gas core nuclear thermal rockets (the most efficient nuclear-powered rocket engine we could feasibly build without inventing entirely new industries). A solar sail is the most likely candidate for a fast interstellar spacecraft, if it can bee made to withstand the intense thermal flux on a close approach to the parent star.

[magnemoe]

Isn't it folly to use earth system for basis of any alien life form in the first place?

Not necessarily, we can estimate plenty of stuff about an probable intelligent alien. Now if you add civilization to the requirement list the requirements get far stronger.

No we can not predict much about alien life itself, but an inteligent sea species like dolphins could be intelligent but they would never build an civilization at least not past stone age.

This is the probable facts, you might get exceptions but again high chance.

First it will be an oxygen breather, yes you don't need oxygen for life and it might even be other solvents than water but they will provide too lite energy, just very primitive animals on earth before oxygen level become reasonable.

Second it will be warm blooded, again its an energy issue, brains use lots of energy, cold blooded might work but you would be stuck in the tropic until you got modern technology.

Size is harder, too small and you can not carry or supply an large enough brain, now bird brains is far more effective than mammal ones and we might imagine an alien brain being even better, but its still limits, think an large cat or bird and minimum size, you don't want to go too big yes large make a large brain cheaper in upkeep but you need to be an social animal, other humans was the most challenging thing early humans faced. To large and you have to live alone, for the civilization phase large size is an handicap as it will be few of you, this increase by an magnitude for predators.

Small size also make groups, tools and weapons far more useful.

The next is probable in an far higher degree as we have exceptions, first you will be an omnivore or predator, you need an high energy diet, you can not spend all the day grassing and its not very intellectual challenging. Elephants are the exception. Second you will have something like fur or feathers, you are an medium to smaller warm blooded creature and almost all of them has feather or fur, yes we are the exception elephants are another. Note that dinosaurs had feathers, they was also mostly warmblooded, and if you don't have insulation you are stuck in the tropic in the tropic, luckily clothes require an lower tech level than electrical heated environment suits.

Hands or other manipulative organs, this is helpful for making tools who increase your numbers and drive intelligence on and an requirements for an civilization.

Next don't go crazy, lots of stuff insects do don't scale up, in short your jaw will probably work as our or the dinosaurs or fish as it gives maximum pressure, eyes will looks like our or fish or octopuses, eyes was developed multiple times. You will have an head, you need an pod to place to put eyes and moth and you want to keep brain close to eyes.

Yes things will be different, numbers of fingers is random from the first successful species, you don't want to go below three or you have an serious problem, six limbs on the other had will give serious benefits as its easy to use the front limbs as hands. The six limb, social flightless bird looks like an winner to me.

You can also imagine other weird solutions on various problems, why do we breath trough the mouth why not an separate breathing channel. Because lungfish breath with their flotation bladder they filled trough their mouth. Spines can be different, why not an twin spine like an bicycle chain, more structural stability and you might end up with two prehensile tails.

Still for walking I belive it will probably will be the dinosaur or bird style with an heavy balancing tail, our style, perhaps an compromise would work even better you are more upright than an dinosaur and have an thinner tail, 6 or more limbs and centaur style but without the 90 degree bend would also work very well and give the bonus of easy hands.

And yes for an advanced civilization you have to be an land animal, or at least be able to function on land, you must have manipulate organs and you need to not only be social but also be able to organize in large groups, you also need to be curious and intelligent enough, you must be numerous so you would be able to live many places not only eat tropical fruits.

[KerikBalm]

First it will be an oxygen breather, yes you don't need oxygen for life and it might even be other solvents than water but they will provide too lite energy, just very primitive animals on earth before oxygen level become reasonable.

I think you've already started with a bad assumption.

Glycolysis provides far more power (energy/time) tha aerobic respiration. It simply gets used up fast. Its still possible. Plenty of organisms on Earth don't use oxygen.

Two: there are animals that don't breath oxygen.

http://www.biomedcentral.com/1741-7007/8/31

Life can and does use sulfer/sulfate as a terminal electron acceptor. Sure its not a gas, but it works if you're aquatic.

http://en.wikipedia.org/wiki/Sulfate-reducing_bacteria

Second it will be warm blooded, again its an energy issue, brains use lots of energy, cold blooded might work but you would be stuck in the tropic until you got modern technology.

Warm blooeded vs cold blooded is so imprecise, and there are so many intermediates... I wish these imprecise terms would just die.

That said, the terms are meaningless as there is no clear distinction, and this prediction becomes quite vague.

The next is probable in an far higher degree as we have exceptions, first you will be an omnivore or predator, you need an high energy diet, you can not spend all the day grassing and its not very intellectual challenging. Elephants are the exception.

Uhhh... because vegetarian humans don't exist? Because vegetarian apes don't exist?

Sure, chimps are omnivores... but Gorrilas aren't. As far as I know, Orangutans aren't. Most primates don't eat meat.

Based on the jaws of many early hominids, many didn't eat meat.

That said, an intelligent animal that starts a civilization that spreads across multiple climates and areas will be adaptable, and will likely use whatever food source is available.

This may include meat, or they may simply change the environment to cultivate the "plants" they already have, or domesticate new ones.

This is another bad assumption

Second you will have something like fur or feathers, you are an medium to smaller warm blooded creature and almost all of them has feather or fur, yes we are the exception elephants are another. Note that dinosaurs had feathers, they was also mostly warmblooded, and if you don't have insulation you are stuck in the tropic in the tropic, luckily clothes require an lower tech level than electrical heated environment suits.

Well, that depends to a large degree on the planet they are on. It also depends how "warm blooded" they are. It also depends how big they are (ie, gigantothermy pretty much means you don't need such insulation). For all we know they are aquatic, and lack such developments (although if aquatic, I would imagine they live in shallow water, which are the conditions that tertrapods with limbs with fingers and such first evolved)

Bad assumption

Hands or other manipulative organs, this is helpful for making tools who increase your numbers and drive intelligence on and an requirements for an civilization.

Yes, I think they would need some pretty good manupulative organs.

Doplhins can be arbitrarily smart, but they won't be able to do much with it... an otter on the other hand... maybe even an octopus.

you need an pod to place to put eyes and moth and you want to keep brain close to eyes.

The brain close to the eyes (the primary eyes) does make sense for reaction time. The mouth may not be anywhere near the eyes/brain/head.

Eyes could be on the torso, and the brain in the torso...

why do we breath trough the mouth why not an separate breathing channel. Because lungfish breath with their flotation bladder they filled trough their mouth.

We do have a separate channel... our nose. Whales do it quite well. Many tetrapods evolved the ability to breath and swallow at the same time.

why not an twin spine like an bicycle chain, more structural stability and you might end up with two prehensile tails.

That would only be more structurally stable if it was in tension, not compression... and tension makes no sense.

And yes for an advanced civilization you have to be an land animal, or at least be able to function on land, you must have manipulate organs and you need to not only be social but also be able to organize in large groups, you also need to be curious and intelligent enough, you must be numerous so you would be able to live many places not only eat tropical fruits.

Define advanced? I could imagine at least stone age level civilizations, with aquaculture, social heirarchys, and such from aquatic animals.

Depending on the land sturcture, they may never need to adapt to survive on land for long periods.

If most land is in archipelago form, then something like a seal with grasping hands could crawl its way on to land, do what it needs to do as far as fire and such is concerned, then return to the water.

[-Velocity-]

...

Most of your post I agree with or at least find your logic agreeable. However, the whole point of this topic was those ideas you by which you were predicting the form of an intelligent alien were largely based on the premise that the intelligent alien evolved in nature. My point is that once a civilization is established, the rules of nature become invalid. Creatures who have created a civilization are subject to wholly different rules and pressures. An advanced civilization probably just 100 years more advanced than ours also has access to the ability to radically and rapidly evolve themselves along routes of their own choosing. Such a civilization probably also has intelligent machines, and may be integrating biological and synthetic components together.

So to reiterate, once a species reaches civilization and in particular, an advanced civilization, then we can forget about trying to use natural selection to predict what the species might look like, because they don't play by the rules of natural selection, and they have the ability to intelligently evolve themselves. Only with young civilizations- like ours- will the laws of natural selection be a sure indicator as to what an intelligent species will look like.

For all we know, our descendants 10 million years from now will have ten legs, be covered in fur, stand only half a meter tall, have a brain 1/10 the volume of ours but that is 1000X more efficient than ours thus making them like 100X smarter than us, and reproduce by copulating with a "species" of intelligent machine that, instead of sperm, ejaculates artificial life forms/"nanites" that help to shape the developing fetus in ways nature couldn't have imagined. It sounds ridiculous, but as long as civilization is maintained for enough total time, then who the hell knows how we will evolve. Unnatural things can and WILL happen, because civilization itself is, by definition, unnatural.

Edited April 21, 2015 by |Velocity|

[AngelLestat]

We can make our predictions using as example the design of each living being on earth, that would increase the chances to be more accurate in our predictions.. But this doesn´t mean that the most common design type of intelligent life (or just life) is like us, maybe life on earth is not the rule.. perhaps is the exception.

Life on earth already gave us a clue, we all descended from a common ancestor, but now we have 2 millions species which each one is very different from the other, then we need to count all the designs which fail due extreme causes over the past, that will rise the number a lot. And that is just 1 example from a common anscestor (which it may be thousands of possible types) and from 1 enviroment (which it may be millions of different types).

Then taking into account all that.. the people who said that they can predict how alien life would look like, are crazy. We dont have the intelligence, neither the creativity and neither the imagination to such task.

Look a cat and see the logic behind its design doesn´t require much intelligence. First we know that if survive all that long, then is doing something right, but a cat is very complex, is not just skin, legs and eyes; you also have a nervous system, protection against germs, etc. So if you want to imagine a different creature from scratch, you need to take into account all that, because its survival chance depends of many factors which may be very different in different enviroments.

Replicator: We dont know how it was our replicator base, but involve into a system called ADN. This molecule carry all the information to design the whole being, it has a complex mechanism to choose what info select depending in its current position over the being. But this is the only possible system base for life? If we try we can imagine many different possible mechanism to produce living beings. Is hard.. but we know that there is always many solutions for a single problem.

Intelligence: All animals are intelligent in their own way, they analyze situations and act accordy all the time, our antropologic centered view always manage to put a barrier between animals and we, animals acts with instincts, we use our intelligence-- we always said... To those who study animal behavior knows that this type of thinking is very dumb of our part.

Culture is what it gave us all the things we accomplish and see all days. Culture involves super fast, so maybe an small change in a different species may allow it to transmit its experiences and knowledge to the next generations with a way to save that info. In that case they would be the higher develope species instead us, and it doesn´t has nothing to do with what they eat our if they have hands or not. Culture overseed all those issues.

[magnemoe]

I think you've already started with a bad assumption.

Glycolysis provides far more power (energy/time) tha aerobic respiration. It simply gets used up fast. Its still possible. Plenty of organisms on Earth don't use oxygen.

Two: there are animals that don't breath oxygen.

http://www.biomedcentral.com/1741-7007/8/31

Life can and does use sulfer/sulfate as a terminal electron acceptor. Sure its not a gas, but it works if you're aquatic.

http://en.wikipedia.org/wiki/Sulfate-reducing_bacteria

Yes but Glycolysis is an produced energy source for peak performance. You need high energy input too.

Note we talk about intelligent life here not just life where I agree the variations is to large to make predictions.

Also not saying its impossible with advanced life without oxygen, just unlikely.

Uhhh... because vegetarian humans don't exist? Because vegetarian apes don't exist?

Sure, chimps are omnivores... but Gorrilas aren't. As far as I know, Orangutans aren't. Most primates don't eat meat.

Based on the jaws of many early hominids, many didn't eat meat.

That said, an intelligent animal that starts a civilization that spreads across multiple climates and areas will be adaptable, and will likely use whatever food source is available.

This may include meat, or they may simply change the environment to cultivate the "plants" they already have, or domesticate new ones.

This is another bad assumption

It exists, and is pretty common, but you would want high energy food, without meat you can use fruits, berries and roots however the two first only exist year around in the tropic.

Eating anything make you an omnivore anyway. Most of this issues goes away with agriculture however before that it will be bad to be dependent on just a few plants as it leaves you vulnerable.

If you are larger you can get away with lower quality food but size has other downsides.

Warm blooeded vs cold blooded is so imprecise, and there are so many intermediates... I wish these imprecise terms would just die.

That said, the terms are meaningless as there is no clear distinction, and this prediction becomes quite vague.

Well, that depends to a large degree on the planet they are on. It also depends how "warm blooded" they are. It also depends how big they are (ie, gigantothermy pretty much means you don't need such insulation). For all we know they are aquatic, and lack such developments (although if aquatic, I would imagine they live in shallow water, which are the conditions that tertrapods with limbs with fingers and such first evolved)

Bad assumption

Did not know it was many intermediates for warm blooded but imagine many dinosaurs was so.

And you are right about tropical climate, on an warmer planet warmblooded might not be so important.

Yes, I think they would need some pretty good manupulative organs.

Doplhins can be arbitrarily smart, but they won't be able to do much with it... an otter on the other hand... maybe even an octopus.

The brain close to the eyes (the primary eyes) does make sense for reaction time. The mouth may not be anywhere near the eyes/brain/head.

Eyes could be on the torso, and the brain in the torso...

Benefit of having the moth near eyes is that you can move it and easy see where you are biting but you are right outside of this.

We do have a separate channel... our nose. Whales do it quite well. Many tetrapods evolved the ability to breath and swallow at the same time.

That would only be more structurally stable if it was in tension, not compression... and tension makes no sense.

Define advanced? I could imagine at least stone age level civilizations, with aquaculture, social heirarchys, and such from aquatic animals.

Depending on the land sturcture, they may never need to adapt to survive on land for long periods.

If most land is in archipelago form, then something like a seal with grasping hands could crawl its way on to land, do what it needs to do as far as fire and such is concerned, then return to the water.

My wrong, should said technological civilization. And something amphibious should probably work.

[magnemoe]

Most of your post I agree with or at least find your logic agreeable. However, the whole point of this topic was those ideas you by which you were predicting the form of an intelligent alien were largely based on the premise that the intelligent alien evolved in nature. My point is that once a civilization is established, the rules of nature become invalid. Creatures who have created a civilization are subject to wholly different rules and pressures. An advanced civilization probably just 100 years more advanced than ours also has access to the ability to radically and rapidly evolve themselves along routes of their own choosing. Such a civilization probably also has intelligent machines, and may be integrating biological and synthetic components together.

So to reiterate, once a species reaches civilization and in particular, an advanced civilization, then we can forget about trying to use natural selection to predict what the species might look like, because they don't play by the rules of natural selection, and they have the ability to intelligently evolve themselves. Only with young civilizations- like ours- will the laws of natural selection be a sure indicator as to what an intelligent species will look like.

For all we know, our descendants 10 million years from now will have ten legs, be covered in fur, stand only half a meter tall, have a brain 1/10 the volume of ours but that is 1000X more efficient than ours thus making them like 100X smarter than us, and reproduce by copulating with a "species" of intelligent machine that, instead of sperm, ejaculates artificial life forms/"nanites" that help to shape the developing fetus in ways nature couldn't have imagined. It sounds ridiculous, but as long as civilization is maintained for enough total time, then who the hell knows how we will evolve. Unnatural things can and WILL happen, because civilization itself is, by definition, unnatural.

I agree, posted something about this earlier, once you start playing with your genes all bets are off but even this follows some rules. Human races diverges more than adaption and random drift, good chance different beauty ideals helped increase the differences.

Some features are general improvements and will be universal, yes it will be multiple versions of them but everybody will have some of it. Disease and cancer resistance, increased living age, direct computer interface is just a few most obvious. However this don't change the body.

Changes on body will mostly depend on fashion who again depend on who subculture you belong to, goths and the Japanese Otaku culture will generate some serious weird stuff, however don't see much want to change human body plan a lot except perhaps bringing back the tail, yes we get elves probably Klingon and catgirls too.

Water breathing would be interesting but water contains too little oxygen for us

Still over deep time GM will generate an way faster change than evolution, we will probably end up as different species. Not so much for utility, tools and an brain-computer interface make it less relevant. I we get to other stars this will increase difference, need to adapt to another ecosystem and the communication delay will generate an split.