# Extra-Terrestrial Questions
**URL:** https://boards.straightdope.com/t/extra-terrestrial-questions/155602
**Category:** Great Debates
**Created:** [February 17, 2003, 9:19am UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602 "2003-02-17T09:19:40Z")
**Posts on this page:** 20
**Page:** 2
### Author:  [@Lemur866](https://boards.straightdope.com/u/Lemur866)
#### Post date: [February 17, 2003, 10:45pm UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/21 "2003-02-17T22:45:09Z")
Well, the Drake equation isn’t supposed to provide ANSWERS, it is merely to get you to start thinking about the question. Obviously, many of the terms in the equation are unknown. But we can make plausible sounding guesses as to some of the values.
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### Author:  [@NutWrench](https://boards.straightdope.com/u/NutWrench)
#### Post date: [February 17, 2003, 11:25pm UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/22 "2003-02-17T23:25:58Z")
I think most intelligent races we encounter will be descended from a reptilian common ancestor.
Having an asteroid slam into the Earth was the biggest break we mammals ever got. Due to that accident, our race could be fairly unique in the galaxy, an exception to ‘normal course of evolution.’
I don’t think aliens will have any interest in our technology and only a passing interest in our history. The only thing really unique about us is our DNA, so sampling it might be the only worthwhile reason for them to visit Earth at all.
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### Author:  [@Meatros](https://boards.straightdope.com/u/Meatros)
#### Post date: [February 17, 2003, 11:48pm UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/23 "2003-02-17T23:48:44Z")
> [@](#):
>
> \*Originally posted by John Mace \*
> \*\*Somewhat of a hijack here, but…
>
> I’m somewhat baffled by the large number of people who believe ETs exist and the large number of people who do not accept evolution (at least as it applies to humans). Seems to me it would be very difficult to hold both views at the same time (believe in ETs but no in evolution). I wonder what the affect on religions would be if life were discovered on other planets. I guess people find it easy to believe that God created life throughout the universe, and not just on Earth. \*\*
In regards to evolution, it’s hard _not_ to accept it. I say this because we use it’s fruits all the time, whether it is animal testing or virus immunity. I think about it for a second and I realize, what good would animal testing be if we weren’t somehow related to other animals.
I wonder the same question you do. Actually I’ve started to wonder another similar question: _What if we find life on other planets and we prove conclusively that they didn’t evolve-they were created and had not changed for millenia?_.
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### Author:  [@hardcore](https://boards.straightdope.com/u/hardcore)
#### Post date: [February 18, 2003, 12:15am UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/24 "2003-02-18T00:15:25Z")
> [@](#):
>
> _Originally posted by I, Brian \*
> **A very serious point, though - a common and weak dismissal of sentient alien life claims that if there were any out there, why haven’t they said hello? To which the simplest reply would be - "because they’re not f** _ing stupid." \*\*
I started a thread last year about a topic related to this, concerning the Fermi Paradox. Basically, it asks the question with respect to ET’s \*in our galaxy \*“So… where are they?” Proceeding from the assumption that galactic colonization is feasible, the first sentient species to arise in a galaxy will necessarily find itself to be alone. In the cosmic blink of an eye (i.e. 5 - 10 Million years), this first species spreads throughout the galaxy, thereby precluding a second species from reaching intelligence capable of interstellar flight. Or if the second species did evolve, they would find unmistakable evidence of the first Galactic Empire.
Using that line of reasoning, I suspect we are the sole lifeform able to travel to other planets in our galaxy. We may find other forms of life elsewhere consisting of microbes, or maybe even multicellular life, but we are unlikely to find other beings capable of constructing radio telescopes. Perhaps in a few billion years, when we merge with the Andromeda Galaxy, we will find our cosmic soulmate. That is, if humans can somehow hold out that long.
> [@](#):
>
> \*Originally posted by Diogenes the Cynic \*
> **Given the tremendous vastness of space, it would take hundreds or thousands of years to travel between all but the very closest stars, even at the speed of light. This would make remote communication close to impossible and interstellar travel even more so.**
A minor nitpick… if we could travel at just 10% of lightspeed (admittedly a huge challenge), we would reach Alpha Centauri in only 43 years. Remote communication would definitely be possible, with only a 4.3 year lag time between messages.
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### Author:  [@elucidator](https://boards.straightdope.com/u/elucidator)
#### Post date: [February 18, 2003, 12:26am UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/25 "2003-02-18T00:26:03Z")
The Intergalactic Chat Room:
“Hi” _(4.3 years…)_
“Hi!” _(4.3 years…)_
“LOL!” _(4.3 years…)_
“ROFLMAO!” _(4.3 years…)_
“CYA” _(4.3 years…)_
“Bi.” _(4.3 years…)_
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### Author:  [@elucidator](https://boards.straightdope.com/u/elucidator)
#### Post date: [February 18, 2003, 12:43am UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/26 "2003-02-18T00:43:33Z")
But seriously folks…
My take on the Drake Equation… The most fundamental question lies with the vigor and hardiness of life itself. For a long time, I remember the common wisdom held that life was of such fragility that only the optimum conditions, i.e., Earth would permit its existence. This in support of the conjecture that it life itself, never mind intellilgent life, might be native and unique to Earth. This mode of thinking is entirely too close to Creationism for my taste.
But recently we have been discovering that life forms are not such a tenuous probability. Bacteria grows in thermal vents in the ocean depths, at a pressure and temperature that would make an entirely practical sterilizing apparatus. Looked at from the other end of the telescope, so to speak, life is not unlikely, it’s damned near inevitable.
The one thing that does bug me is the complexity and mind-boggling improbability of the _first_ DNA molecule. Its kind of like a gazillion mile wide rotating bin filled with all the stock from a couple of billion Radio Shacks. It turns a couple of billion times and by sheer accident a crude computer assembles, and then replicates itself from the parts at hand.
That part still kinda irks me.
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### Author:  [@MEBuckner](https://boards.straightdope.com/u/MEBuckner)
#### Post date: [February 18, 2003, 6:44am UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/27 "2003-02-18T06:44:32Z")
> [@](#):
>
> \*Originally posted by Aesiron \*
> Aside from that, I do agree with you that I don’t believe the hominid shape to be universal in any regard but I suffer from a lack of imagination and can’t really think of how much good a sentient pachyderm could do 'cause of the inherent limits of its bodies. For instance, if we didn’t have our arms and hands free (with our handy-dandy opposable thumbs), we wouldn’t be an industrial society and thus, unremarkable when compared to any other species on earth, right?
But what if we had [prehensile noses](http://www.pbs.org/wnet/nature/elephants/trunk.html)?
> [@](#):
>
> \*Originally posted by NutWrench \*
> I think most intelligent races we encounter will be descended from a reptilian common ancestor.
> Having an asteroid slam into the Earth was the biggest break we mammals ever got. Due to that accident, our race could be fairly unique in the galaxy, an exception to ‘normal course of evolution.’
But how would you have “reptiles” and “mammals” on a distant planet with life which had evolved entirely separately from life on Earth?
Terms like “[autotroph](http://www.bartleby.com/61/6/A0540600.html)” and “[heterotroph](http://www.bartleby.com/61/88/H0178875.html)”, “[exoskeleton](http://www.bartleby.com/61/4/E0280400.html)” and “[endoskeleton](http://www.bartleby.com/61/73/E0137300.html)” (though you will have to disregard that part about “derived from the mesoderm”), or “[homeotherm](http://www.bartleby.com/61/18/H0251800.html)” and “[poikilotherm](http://www.bartleby.com/61/0/P0400000.html)”, being functional rather than genealogical descriptions of things, might apply to lifeforms on many planets; but you won’t find “crustaceans”, “insects”, “reptiles”, or “mammals” on other planets (unless we take them there).
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### Author:  [@Electronic\_Chaos](https://boards.straightdope.com/u/Electronic_Chaos)
#### Post date: [February 18, 2003, 9:10am UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/28 "2003-02-18T09:10:09Z")
If the universe is, in fact, infinite, and life evolving anywhere is possible, then it is also very probable. No matter what the odds, when working with infinite space…anything is possible.
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### Author:  [@coax](https://boards.straightdope.com/u/coax)
#### Post date: [February 18, 2003, 10:26am UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/29 "2003-02-18T10:26:41Z")
I wonder, what precursors must be in place for intelligent life to exist?
The way I see it with earth and humans, if the meteor didn’t hit 65 mil years ago, humans would not exist.
We would have alot of dinosaurs and other mammals and insects running around.
Presuming this alien race lives somewhere in our universe, they too must have began life as a small bacteria during the big bang, right?
And if so, what’s the probability that their planet got hit by an asteroid/comet/whatever.
And if it didn’t, could life have evolved over these years into intelligent life, with lots of carnivores running around and uninterrupted without being disturbed?
Maybe I’m way off base, but I’m just contemplating the idea.
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### Author:  [@MEBuckner](https://boards.straightdope.com/u/MEBuckner)
#### Post date: [February 18, 2003, 11:15am UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/30 "2003-02-18T11:15:37Z")
> [@](#):
>
> Presuming this alien race lives somewhere in our universe, they too must have began life as a small bacteria during the big bang, right?
The Big Bang isn’t really related to the origin of life on Earth or any other planet, except in the sense that the Big Bang is related to _everything_. The Big Bang was the singularity at the beginning of the entire Universe, 13.7 billion years ago according to the latest figure. Earth and the Solar System formed only about 4.5 billion years ago, and life on Earth arose maybe a billion years after that.
> [@](#):
>
> And if so, what’s the probability that their planet got hit by an asteroid/comet/whatever.
Earth has probably been hit by many comets and asteroids in its history, and probably any other planet will be the same way. In fact, from **tclouie** ’s post, some have suggested that a factor which would hamper the development of life is that worlds in other star systems with different arrangements of planets and moons might get hit by too many asteroids and comets. There have also been numerous mass extinction events in Earth’s history, the Cretaceous-Tertiary one (which killed the dinosaurs) is just the most well known. Some of the others may also have been caused by asteroid impacts, and others by other things.
Dinosaurs lived for about 150 million years before the great dying at the end of the Cretaceous. Conversely, it was nearly 65 million years after the end of the dinosaurs that intelligent life arose. (In terms of species diversity, the planet’s biosphere recovered from the mass extinction long before then.) The point really is that no one exactly knows why intelligent life evolved exactly when it did. On a long enough time scale, evolution _has_ been “progressive”–2 billion years ago, or even 1 billion years ago, there wasn’t even multicellular life, let alone intelligent life. Only in the last half-billion years has life “advanced” to the point of evolving big enough things to support intelligence. (I don’t _think_ there’s any way single-celled bacteria-like organisms could ever evolve language, tool use, and self-awareness, although in terms of survival and reproduction they are highly successful.) On the other hand, as far as I know we don’t believe there’s any real reason to think mammals are necessarily more “complex” or more “advanced” than dinosaurs were. Some people have even speculated about some they hadn’t gone extinct. (But then, why didn’t they in the tens of millions of years _before_ they went extinct?) So, intelligent life probably _could_ have evolved at many points in the last couple of hundred million years, but it didn’t. It’s not that life on Earth during that time was uniformly advancing towards intelligence, or that all those millions of years were somehow laying some foundation for intelligence. Maybe it’s just a question of the odds–during any particular period, the chances of some species acquiring sapience just aren’t all that high. We don’t really have a good handle on this, because we only have one example of the evolution of an intelligent species (ourselves). By contrast, we know things like eyes have evolved many, many times; flying has evolved at least four times–in insects, pterosaurs, birds, and bats. So, once other life-bearing Earth-like planets evolved large (multicellular-scale) life–this took a long time on Earth, most of the history of life on Earth consists of single-celled organisms, so macroscopic life may also be in some sense unlikely to arise–we should expect to find lifeforms with light-sensing organs, and probably see things flying through the air. But intelligence is a very big question mark.
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### Author:  [@G.Cornelius](https://boards.straightdope.com/u/G.Cornelius)
#### Post date: [February 18, 2003, 1:22pm UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/31 "2003-02-18T13:22:18Z")
> [@](#):
>
> \*Originally posted by xgxlx \*
> \*\*If the universe is, in fact, infinite, and life evolving anywhere is possible, then it is also very probable. No matter what the odds, when working with infinite space…anything is possible. \*\*
AFAIK the current most commonly accepted scientific view is the the universe is finite in both time and space.
Logically, if the universe is indeed infinite then everything that is possible must actually exist somewhere - e.g a galaxy made entirely of chocolate.
This kind of argument is really not very helpful. Indeed, any discussion of extraterrestial life must take care to make the distiction between the probability of ET life somewhere and sometime in the universe **versus** the probability of ET life within a communicable distance.
Unless one believes that the earth a special and unique creation it seems very reasonable to say that there exist other places in the universe where life has evolved.
The hard questions are, what is the probability of there being ET life that we can actually detect (even indirectly) and what is the probability of inteligent ET life with which we might be able to communicate (or at least ‘listen’ to). This certainly means restricting the question to our own galaxy.
The milky way is 100,000 light years in diameter and contains something like 10^12 stars. Big cetainly, but even the Drake Equation will quickly make inroads into this number. Some very reasonable adjustments to the Drake equation have been proposed and these make the probability of ET life within the milky way seem quite low.
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### Author:  [@scr4](https://boards.straightdope.com/u/scr4)
#### Post date: [February 18, 2003, 1:27pm UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/32 "2003-02-18T13:27:08Z")
> [@](#):
>
> \*Originally posted by xgxlx \*
> \*\*If the universe is, in fact, infinite, and life evolving anywhere is possible, then it is also very probable. \*\*
If it is truly infinite then, as Douglas Adams said, every conceivable type of life form exists somewhere. You don’t have to manufacture anything because anything you can imagine (mattresses, ratchet screwdrivers, you name it) grows somewhere.
Seriously though, the universe is not infinite. At least, the part of the universe we can see and interact with is finite.
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### Author:  [@Dijon\_Warlock](https://boards.straightdope.com/u/Dijon_Warlock)
#### Post date: [February 18, 2003, 3:49pm UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/33 "2003-02-18T15:49:17Z")
Another way of looking at it: if indeed there _isn’t_ extra-terrestrial life out there, then we are the only planet in the universe for which that is true. I guess we _could_ be the sole exception to the rule, but those are some pretty tall odds.
Now the question is, does that sound as stupid as I think it does? Yeah, probably…
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### Author:  [@eburacum45](https://boards.straightdope.com/u/eburacum45)
#### Post date: [February 20, 2003, 5:27pm UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/34 "2003-02-20T17:27:52Z")
Putting aside the Drake equasion,
if there is one earth-like planet (with multicellular life and an oxygen atmosphere) (sometimes usefully referred to as [Gaian worlds](http://www.orionsarm.com/eg/g/Ga-Gd.html#Gaian_type)) in every ten thousand stars
this would make a grand total of 100,000,000 earth-like planets in our galaxy.
The central region of the galaxy probably has too much radiation flux to allow multicellular life to evolve-
although the example of [Deinococcus radiodurans](http://www.orionsarm.com/eg/d/De-Dh.html#Deinococcus)probably means that some sort of life is possible there…
Perhaps intelligence exists currently on one Gaian world out of every hundred thousand -
this still allows for a thousand worlds with intelligent life right now-
Nine out of ten of these might be isolationist and not interested in space flight
this means a hundred spacefaring species in our galaxy right now-
There is also, im my opinion, perhaps a chance that some forms of life could tolerate or thrive in environments that are very different to the Earth
none of these are likely to be remotely humanoid
but may come in various [shapes and sizes](http://www.orionsarm.com/aliens/index.html)
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### Author:  [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)
#### Post date: [February 20, 2003, 7:09pm UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/35 "2003-02-20T19:09:06Z")
> [@](#):
>
> \*Originally posted by eburacum45 \*
> \*\*Putting aside the Drake equasion,
> if there is one earth-like planet in every ten thousand stars
> this would make a grand total of 100,000,000 earth-like planets in our galaxy.
> Perhaps intelligence exists currently on one Gaian world out of every hundred thousand -
> this still allows for a thousand worlds with intelligent life right now-
> Nine out of ten of these might be isolationist and not interested in space flight
> this means a hundred spacefaring species in our galaxy right now-
> There is also, im my opinion, perhaps a chance that some forms of life could tolerate or thrive in environments that are very different to the Earth
> none of these are likely to be remotely humanoid
> but may come in various \*\*
You say you’re putting aside the Drake equation but then rephrase it to make your point.
I’ll rephrase my objection to the Drake equation. It isn’t science. As I have heard elsewhere, and as **lemur866** pointed out, it is just to get a person thinking about the possibilities of life elsewhere. If that’s the case all Drake had to say was, “With the myriad stars in the Universe doesn’t it seem likely that there is life elsewhere?”
It is the mathematical trappings he draped around a purely intuituve concept that I don’t like. Especially when the equation has been trooted out innumerable times as some sort of “proof” of life elsewhere.
Cheerio
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### Author:  [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)
#### Post date: [February 20, 2003, 7:10pm UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/36 "2003-02-20T19:10:15Z")
And what the hell did I mean by _trooted_?
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### Author:  [@Chanticleer](https://boards.straightdope.com/u/Chanticleer)
#### Post date: [February 20, 2003, 7:50pm UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/37 "2003-02-20T19:50:15Z")
> [@](#):
>
> \*Originally posted by andymurph64 \*
> \*\*Is multi-celled life that easy to evolve? If so, why did it take so long? \*\*
As used here, the words **easy** and **long** are relative terms. Easy as compared to what? Or, long compared to what. To humans, a life of 5 years is short but to a fruitfly it is very very long. So to us it may seem like a long time when we only have our own experience or imagination to compare it with, but maybe, just maybe, in the grand scheme of things, it didn’t take that long at all.
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### Author:  [@andymurph64](https://boards.straightdope.com/u/andymurph64)
#### Post date: [February 20, 2003, 7:54pm UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/38 "2003-02-20T19:54:34Z")
> [@](#):
>
> but maybe, just maybe, in the grand scheme of things, it didn’t take that long at all.
If that were the case, then multi-celled life would be rare because the planets would be unihabitable due to the lifespan of the star. I know it’s relative but it did take a long time for mult-celled life to develop on Earth compared to the sun’s lifespan.
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### Author:  [@eburacum45](https://boards.straightdope.com/u/eburacum45)
#### Post date: [February 20, 2003, 8:03pm UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/39 "2003-02-20T20:03:43Z")
> [@](#):
>
> \*Originally posted by MonkeyMensch \*
> \*\*You say you’re putting aside the Drake equation but then rephrase it to make your point.
>
> I’ll rephrase my objection to the Drake equation. It isn’t science.
>
> \*\*
Agreed. I was approaching it as an imaginative exercise.
We won’t know these things until we have surveyed the galaxy or a representativepart of it…
which leads me on to Fermi- if any other species out there wants to know the answer to the same question, where are their probes?
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### Author:  [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)
#### Post date: [February 20, 2003, 8:36pm UTC](https://boards.straightdope.com/t/extra-terrestrial-questions/155602/40 "2003-02-20T20:36:05Z")
I am trying to think of book I have read (maybe _Footfall?_ )that, in a sense, answers ther Fermi paradox. Big, bad civilizations listen for the newly communicative civs and then come beat 'em up for their planetary resources.
The metaphor is “There ain’t no civilizations peeping 'cause the sky is full of hawks.”
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