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Author Topic:   Antropic Principle and Extraterrestrial Life
jar
Member (Idle past 393 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 16 of 26 (156588)
11-06-2004 7:34 AM
Reply to: Message 1 by The Dread Dormammu
11-05-2004 5:00 PM


What is intellegent life?
If we look at our history, humans capable of communicating beyond our local neighborhood, we can say that intellegent life has been around for just over 100 years. But even within that short period, we have seen several major changes in technology. There was plain old radio, then tv and now digital broadcasts. In addition, the advent of satellite tansportation means that the actual number of radiating sources has probably gone down and their directionality has gone up. Instead of sources broadcasting wide area patterns, modern sources radiate as narrow, directed a beam as possible towards a specific site, the satellite used for relay.
What that means is that there may well be a very small window when remote detection of human like civilizations is possible.
In addition, the existence of human like critters is yet another tiny percentage of the time life has been around in the one example we're familar with. And of the various critters that have lived, we are still so new that the jury is out on whether or not we will be successful or even significant.
On the otherhand, if we look at the Universe it appears that all the laws we know of work about the same everywhere. So far we have found no real examples of known laws or effects behaving in a totally unexpected way.
If that is the case, and if it is a fact that known laws are universal, I see no reason not to expect life to originate most everywhere.

Aslan is not a Tame Lion

This message is a reply to:
 Message 1 by The Dread Dormammu, posted 11-05-2004 5:00 PM The Dread Dormammu has replied

Replies to this message:
 Message 19 by The Dread Dormammu, posted 11-06-2004 4:11 PM jar has not replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 17 of 26 (156673)
11-06-2004 2:05 PM
Reply to: Message 11 by RustyShackelford
11-05-2004 9:58 PM


Not like us
You're assuming that they would be enough like us to want the earth. It is possible they would consider it either too hot or too cold or too a lot of other things.
The force of gravity here could be greater than they are comfortable with or too low.
While life might have to be a lot like us (that is not methane breathing etc.) that doesn't mean they can't be pretty darn different. If we have unicellular life that dies of hypothermia if the water isn't at the boiling point around them then perhaps anything less than 50 or 60 degrees C is too low for these potential visitors.

This message is a reply to:
 Message 11 by RustyShackelford, posted 11-05-2004 9:58 PM RustyShackelford has not replied

Replies to this message:
 Message 18 by The Dread Dormammu, posted 11-06-2004 3:57 PM NosyNed has replied

  
The Dread Dormammu
Inactive Member


Message 18 of 26 (156697)
11-06-2004 3:57 PM
Reply to: Message 17 by NosyNed
11-06-2004 2:05 PM


Re: Not like us
I find your post very confusing ned, I thought you beleved in the power of evolution.
Anything advanced enough to be capable of launching a planetary invasion would probably be able to harness that power through biotechnology (or if they are robotic, engineering). Do you disagree?

This message is a reply to:
 Message 17 by NosyNed, posted 11-06-2004 2:05 PM NosyNed has replied

Replies to this message:
 Message 21 by NosyNed, posted 11-06-2004 5:33 PM The Dread Dormammu has not replied

  
The Dread Dormammu
Inactive Member


Message 19 of 26 (156702)
11-06-2004 4:11 PM
Reply to: Message 16 by jar
11-06-2004 7:34 AM


Good point
I think Jar makes some great points.
Instead of sources broadcasting wide area patterns, modern sources radiate as narrow, directed a beam as possible towards a specific site, the satellite used for relay.
This is why SETI is now looking for lasers right? But if advanced civilizations do use very directional communication they are going to be a lot harder to find. That is if they don't want to be found.
we are still so new that the jury is out on whether or not we will be successful or even significant.
Well we are significant enough to possibly be causing another major extiction.
If that is the case, and if it is a fact that known laws are universal, I see no reason not to expect life to originate most everywhere.
All we know about the laws of physics is that it allows life to exisit! We have no way of knowing how likely abiogeniesis (am I using thei word properly?) is until we start doing some surveys of our universe. This is why I'm so exited about that probe they are going to send to Europa becase we can maby start to get a feel for how common life is.

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The Dread Dormammu
Inactive Member


Message 20 of 26 (156704)
11-06-2004 4:21 PM
Reply to: Message 15 by pink sasquatch
11-06-2004 2:28 AM


Re: Thats not the point
We count as intelligent life, and we aren't interstellar colonizers, and may never be.
Why does "intelligent life elsewhere in the universe" have to mean superintelligent technologically advanced planet hoppers?
It doesn't. But if intellegent life is very common there will be many civilizations and a few of them might be "SITAPHs" (superintellegent technologicaly advanced planet hoppers). AND it won't take all that long for the SITAPHs to colonize the galaxy.
Incedentaly I think we should rememeber that the whole civilization isn't moving in this theory. They are just sending out seeds.

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 Message 15 by pink sasquatch, posted 11-06-2004 2:28 AM pink sasquatch has not replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 21 of 26 (156737)
11-06-2004 5:33 PM
Reply to: Message 18 by The Dread Dormammu
11-06-2004 3:57 PM


The power of evolution
I see so much power in the evolutionary process that I am willing to give a bit of credance to the idea that it could have been the extremophiles that were the base for the evolution of multicellular life and then SITAPHS.
I think I'm also suggesting that there are enough "habitable" worlds that the SITAPHS can pick and choose and ignore those that aren't close enough.
It may well be that getting to intersteller travel is still very difficult. It is not at all clear, for example, that we will (in the way we mean here). So if intelligent life is only moderately common (1,000's in a galaxy), spread over perhaps 100 very different types of biosheres and only 1 in ten get to intersteller travel we end up with perhaps a handful in the galaxy who might be interested in Earth and able to get here. If we are lucky enough that all of them can show some restraint and leave other intelligences alone then we are safe.
(I'm completely discounting the possibility of successfull intergalactic travel)

This message is a reply to:
 Message 18 by The Dread Dormammu, posted 11-06-2004 3:57 PM The Dread Dormammu has not replied

  
Loudmouth
Inactive Member


Message 22 of 26 (157295)
11-08-2004 1:17 PM


My two cents
Since we are all throwing crazy ideas around, I thought I would join in.
The first hurdle for a detectable society is technology. We are focusing on laser and radio waves because this is what humans use. We also assume that societies will use these forms of communication at intensities that would be detectable from great distances. All of these are anthropic assumptions. As our technology advances we may find that, as Jar mentioned, the window of opportunity for detection is only a few centuries long. This is a huge problem.
The second hurdle is for a society to survive the advent of technology. Humans have narrowly missed an all out nuclear war on at least one occasion (Cuban Missle Crisis). There is no guarantee that other societies have not offed themselves due to harnessing the power of the atom or other technologies.
The third hurdle is interstellar travel. We have all grown up with Star Trek, Star Wars, and Battlestar Gallactica. We all assume that fast, interstellar travel is a viable technology. In reality, we have no evidence that interstellar travel is either economically viable or technologically possible. Travelling even at 0.5 c poses radiation problems since harmless wave lengths will be blue shifted into harmful wavelengths. Travelling at slow speeds requires either hibernation or a large amount of supplies. It is much more economically viable to colonize within the solar system, IMHO, than to look elsewhere in the solar system. A Mars colony will save humanity from supervolcanoes and large meteor strikes. However, a Mars colony will not save us from an our sun when it dies and expands outwards.
Just on a hunch, the rise of sapient and intelligent species across the galaxy may be common but detection of these societies may be next to impossible. They may kill themselves off, die off with the death of their sun, or a combination of other factors. Being a gregarious species we like to assume that we are not alone, and we probably aren't. However, saying hi to the neighbors may never happen.

Replies to this message:
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contracycle
Inactive Member


Message 23 of 26 (157959)
11-10-2004 11:20 AM


In no particular order:
Drakes first equation attempted to estimate the frequency of technically identifiable species only, specifically radio-using species. this includes terms for the probability of a species wiping itself out as well (although I'm no sure it contained a term for ecological suicide). This still produced and estimated 10,000 technical species at the present time (that is, not total over the lifetime of the galaxy)
Drakes second equation attempted to estimate the diffusion rate of SITAPH's given a maximum velocity of 0.5c, and concluded that our entire galaxy should have been colonised several billion years before the earth coaelesced.
I disagree that looking for radio is a resort to the anthropic principle. The fact that we find a tool useful, or discover something about the world, does not imply anthropic projection simultaneously. If we are an evolved species without divinie intervention, governed by physics, then the opportunities that we discover should be discovered by other beings similar to ourselves. Radio is not a human invention, it is a discovery. The properties of radio are suitable, at least as far as we are able to determine, to interstellar communication. There may well be BETTER technologies we do not understand yet, of course.
On colonising and interstellar war, I do not think that presently habited or "biological cradle" planet would be at all attractive to interstellar travellers. This is because a species that can cross interstellar distances has already had to solve the problems of permanent space habitation, and does not actualy NEED a biological planet. It would be much more logical for them to park next to Jupiter and simply hoover up what resources they need.

  
contracycle
Inactive Member


Message 24 of 26 (157960)
11-10-2004 11:21 AM
Reply to: Message 15 by pink sasquatch
11-06-2004 2:28 AM


Re: Thats not the point
quote:
Why does "intelligent life elsewhere in the universe" have to mean superintelligent technologically advanced planet hoppers?
BNecuase that is the only type we will be able to find from here. The universe may be full of dolphins for all we know...

This message is a reply to:
 Message 15 by pink sasquatch, posted 11-06-2004 2:28 AM pink sasquatch has not replied

  
The Dread Dormammu
Inactive Member


Message 25 of 26 (159457)
11-14-2004 8:34 PM


So whats the verdict?
So I think we are all in agreement that we have too little information.

  
Ben!
Member (Idle past 1398 days)
Posts: 1161
From: Hayward, CA
Joined: 10-14-2004


Message 26 of 26 (159644)
11-15-2004 8:35 AM
Reply to: Message 22 by Loudmouth
11-08-2004 1:17 PM


Re: My two cents
I'm hip with your 'second hurdle'. I was jammin' on the same def beat.
KIND of related to this thread... I would like to know if anybody knows what kind of gravitational and chemical limitations are set on theories of ambiogenesis...
This would require:
1. some understood, concrete proposals for ambiogenesis
2. a 'buttload' of knowledge of chemistry
3. some phat physics knowledge
this would give us SOME understanding of the limits of 'life as we know it' existing on other planets. For sure, there's got to be other replicating molecules in other planetary gravitational / chemical configurations.. and if you could propose any of those, I'd be all ears for that too.
Come on, there's a lot of smart guys here. Anybody interested to try?
Ben

This message is a reply to:
 Message 22 by Loudmouth, posted 11-08-2004 1:17 PM Loudmouth has not replied

  
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