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#26 2008-05-06 10:52:56

bobunf
Member
From: Phoenix, AZ
Registered: 2005-11-21
Posts: 223

Re: Why No Contact Yet ?

Starting in the 1920’s large amounts of Freon started to be used for refrigeration replacing methyl chloride and other chemicals and greatly expanding the refrigeration market throughout the world.  Much of this Freon leaked into the atmosphere creating ozone holes and the like.  There are all kinds of possibilities for detecting Freon and its effects by spectroscopic analysis. 

Advanced ET 80 light years away would now be following our use of Freon and tracing our industrial development through this one measure alone.  The bubble containing this information now has a radius of about 80 light years.

Bob

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#27 2008-05-06 10:57:37

JoshNH4H
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From: Pullman, WA
Registered: 2007-07-15
Posts: 2,526
Website

Re: Why No Contact Yet ?

oh, ok.  But you would need really advanced telescopes.  And as for finding other users of freon, once they realized the effects, they would replace it, right?


-Josh

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#28 2008-05-06 12:19:42

nickname
Member
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Why No Contact Yet ?

bobunf,

Good point about the detection of earthlike worlds with technical civilizations.
Just check for pollution on that earthlike world and presto you have the indication you need.

We are not quite at that point of seeing earth like worlds then detecting the chemical makeup of those worlds.
We are close though.

Now if we found them with less technology than us in the next few decades as our technology allows us to see the signs of them.
How do we ever talk to them or listen to them?
They wont have a huge dish pointed at us or any indication we exist.

Maybe lots of civilizations know we are here already and are just waiting for us to tune into the right place.
Even with vastly advanced technology star to star travel might be quite difficult, so civilizations just wait until each technical civilization is ready to chat.


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#29 2008-05-06 13:45:04

bobunf
Member
From: Phoenix, AZ
Registered: 2005-11-21
Posts: 223

Re: Why No Contact Yet ?

“so civilizations just wait”

If it were us, I don’t think we’d be that patient.  ETs might be more or less patient than us, or about the same.   

If ETs were sufficiently advanced they could paint images for us on the moon with colored lasers, or produce holographs considerably closer, use our electrical transmissions systems to play us a tone (ala ET), or they might do something we haven’t thought of.

A more ambitious approach might be, once identifying an abode of intelligent life, to send a robot craft to investigate and interact with the new civilization.  Even more ambitious might be to send manned craft or colonizers.  Assuredly, they might say, we have some space left on our magnificent world.  If not, they could make some.

Bob

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#30 2008-05-06 14:39:24

nickname
Member
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Why No Contact Yet ?

bobunf,

Or right now we are insignificant.

They never try to contact anyone because 1000s of civilizations already talk to each other, we are just one more of countless civilizations not quite ready.

Those that can't join in on the chat are deemed to primitive to be worthy of contact.

They also have the same problem as us, we are not listening to the right place or the right type of signal or means of communication.

ET has no need to worry about trying to contact a species without the ability to hear, when they can talk with 1000s who can listen.
When we can hear they will already be talking.

Like Star Trek, no interference until we are deemed worthy.

Lots of reasons are possible why. smile


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#31 2008-05-06 20:17:00

bobunf
Member
From: Phoenix, AZ
Registered: 2005-11-21
Posts: 223

Re: Why No Contact Yet ?

You're supposing that ET will not act like we would--covering the Earth from pole to pole and highest mountain top to deepest ocean canyon.

With 1,000s of civilizaitins with 1,000s of different groups within each civilization, it's hard to credit that none would behave with the same curiosity and gregariousness as us.

It seems unlikely in the extreme that all ET civilizations (if there really are thousands) will be monolithic and mute.

Bob

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#32 2008-05-07 11:20:35

nickname
Member
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Why No Contact Yet ?

bobunf,

What if we are still very primitive.?
We might be 5 years, 5 thousand  or 50 thousand years before we discover how to chat.

Maybe like all primitive cultures on Earth meeting more advanced civilization even from Earth the outcome is bad.

They are sure to be curious like us, but would we be more that just interested in 1 tribe of monkeys over another?
Or would we just give it a passing curious look.?
If the monkeys spoke back to us while looking then sure we would be more than interested.

If we consider that we are low on the totem pole of intelligence and civilization time spans in the universe, then yes most of them will have no reason to contact us other than a passing look.
Planet 12873456b locally called Earth has primitive hostile intelligent life called humans. Note.. check back in 25 thousand years for development and each 25 thousand years.

Expecting civilizations that have been around for many hundreds of thousand to billions of years will think anything like us is simply a human perspective, and probably wrong.

Think about what humanity would be like 100 thousand years from now and we would not be interested in the now us.


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#33 2008-05-07 23:46:15

bobunf
Member
From: Phoenix, AZ
Registered: 2005-11-21
Posts: 223

Re: Why No Contact Yet ?

The problem I have with this scenario is its totally depressing monolithic character.  At least some of the ET civilizations (I really think all) will contain within them groupings of different kinds.  Humans, for instance, have formed very large numbers of significant groups, any one of which could, even today, develop the ability to signal our presence to ETs for many different reasons.  There are:

> About 200 nations, and hundreds of thousands of political sub-divisions.
> Thousands of religious groups.
> Tens of thousands of institutions of higher learning.
> Tens of thousands of observatories and other research centers.
> Tens of thousands of internationally operating non-governmental organizations such as Oxfam, Tropenbos International, the Mars Society or the Ford Foundation.
> Tens of thousands of national non-governmental organizations such as the American Automobile Association or AARP which has an annual budget in excess of $600 million.
> In the United States alone there are over a thousand business enterprises with receipts in excess of $1 billion per year.
> And there are about 100,000 individuals in the world with net worth in excess of $30 million. Any one of these people alone could start a signaling project with our technology.

If even a small percentage of ETs are like us, there will be millions of groups with the ability to signal their presence to us.

I find it hard to credit the idea that none of these millions of groups will want to contact us from
> altruism; suppling us the cure for cancer, Alzheimer’s and addiction, and saving us from numerous plagues and ignorance; or just believing that it is more blessed to give than receive.
> spreading religious truth as they see it, their brand of environmentalism, their political or other ideologies
> a desire to share their culture; art, music, story telling, architecture, and dozens of other creative pursuits
> as a memorial to themselves
> some will just be crazy
> some will be curious about oodles of different things

and there are lots of other reasons I haven’t thought of; maybe that no human has ever thought of.

I imagine that a hundred thousand years from now the human species, if we still exist and have continued technological advancement, will be even more diverse than we are today.  Today, human cultures exist that are hundreds, thousands and even tens of thousands of years technologically behind 21st century industrialized society. 

I don’t think a large percentage of advanced ETs will be monolithic; all lacking in altruism, religious, environmental and other ideological drives, uninterested in showing off their culture or having it remembered by others (no matter how lowly), completely lacking in irrational behaviour and curiosity.

If they really are all that dull and stuck up, maybe we’re better off without.  We’ll certainly do a better job of letting others know we’re here.  We will be the more advanced, generous and caring species.

Bob

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#34 2008-05-08 08:35:15

nickname
Member
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Why No Contact Yet ?

bobunf,

This is my personal belief why it is quiet.
Only a handful of intelligent species exist in the galaxy, they are all very far apart from each other so they talk rather than try to go.

They have a very different means of communications than we use that gets around the light speed communication problems.

A few species as technically advanced as us also exist in the galaxy, but with the technology we have discovering each other is quite difficult, talking to each other another quantum step that requires a persistent long term effort from both worlds.

We could have a few tech civilization trying to talk with us right now, but we simply are not listening to the right star or the means of the communication is so foreign to us we have seen something and believed it to be just noise or a natural signal.

After 100 years of sending a signal to a technically similar species and getting no answer, we would start to get the idea that it's better to wait for them to make contact.
Then our first message to them would be (It's about time, we have been waiting for a few thousand years for you)  LOL


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#35 2008-05-08 12:26:00

bobunf
Member
From: Phoenix, AZ
Registered: 2005-11-21
Posts: 223

Re: Why No Contact Yet ?

Roughly calculating, I think that the average probable distance from Earth of an advanced ET would be about:
22,000 light years if there were 10 such civilizations in the galaxy
7,000 light years if there were 100 such civilizations in the galaxy
2,500 light years if there were 1000 such civilizations in the galaxy (About 1 tenth of a percent of the stars in our galaxy are within about 3500 light years of Earth.  So, with a thousand ETs in the galaxy, we would expect about 1 ET within this sphere of 3500 light year radius—an average of about 2,500 light years from Earth.)

A hundred years from now, looking at a civilization 2500 light years away that was like ours,  we should know that there’s
> a terrestrial planet in the habitable zone with plenty of water and land. 
> with widespread biology from oxygen, ozone, methane, nitrous oxide, chlorophyll and other indications
> we may be able to detect the first indications of agriculture, metal working, coal burning and, perhaps, other indications of pre-industrial civilization

Remember we’ll be seeing this ET 2500 years in its past, since it took light that long to reach us.

After another hundred years of observation we should know something about their cultural trends and, with our sophisticated understanding of cultural evolution developed over the previous 200 years, we may be able to predict that this civilization will now have reached a point where they could receive radio messages. 

What would we do?  Certainly some group amongst us would send radio and, perhaps, other sorts of messages.  This is relatively cheap and easy even today.  Of course, it would be 5,000 years before we heard back, at the earliest, but by 2200 humans may be considerably longer lived than now.  How long would we continue to do this?  Probably for varying periods of time, inconsistently, for who knows how long. 

Assuming that super-luminal communication is not possible, I think this analysis suggests that, for us to expect to hear from ET any time soon, there must be more than 1,000 advanced ETs in our galaxy.  Even if ETs are like us: gregarious, diversified, curious and not stuck-up.

To put it another way, the chance of an advanced ET associated with any given star system must be greater than about 1 to 400 million

Bob

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#36 2008-05-08 12:56:00

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,780

Re: Why No Contact Yet ?

Bob -

I'm not sure you've got this right.

As I understand it the Sun is a late arrival on the cosmic timescale there will be lots of similar solar systems from billions of years ago.

So your average and estimated times must be a bit misleading. Even if there are relatively few of these civilisations in the galaxy surely we should be receiving signals from all parts of the galaxy, many millions of light years away.  Do signals survive inter-galactically? If so, we will be getting them from even further away


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#37 2008-05-08 15:36:51

noosfractal
Member
From: Biosphere 1
Registered: 2005-10-04
Posts: 824
Website

Re: Why No Contact Yet ?

To put it another way, the chance of an advanced ET associated with any given star system must be greater than about 1 to 400 million

However, if you don't assume that interstellar travel is impossible, then even if it is slow, every possible star should have been colonized by now:

- suppose it takes 10,000 years to colonize just one other star system
- suppose only 1% of newly colonized star systems ever colonize another star system
- then the number of colonized star systems will double every 700,000 years or so (by compound interest).
- but it only takes 40 doublings to go from 1 to 1 trillion
- so every possible star system in our galaxy will have been colonized within 28,000,000 years
- which is the blink of an eye, geologically speaking.


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#38 2008-05-08 15:38:16

nickname
Member
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Why No Contact Yet ?

bobunf,

Lets go with the 10 civilizations in this galaxy, the closest being 22,000 LY away from Us.
7 already chat with each other and have very little interest in primitive cultures.
The remaining 3 civilizations are somewhat similar to us.
1 is perfect for distance and development for us to contact.
1 is quite a bit more technically advanced.
1 has just discovered the other land on the other side of its planet.
Another 25 planets exist in the primate sort of stage exist.

In the next 25 years we look at that 1 perfect civilization and discover it's about 22 thousand years away from having radio telescopes and 22 thousand LY away from us.
How we go about looking at the development of the civilization 22 thousand LY away I'm not sure, but lets say we can 25 years from now. smile

So we set up a really big dish and start sending a very powerful signal towards them.

Unfortunately at 20 thousand years the civilization we are sending to already have radio telescopes, they were just a bit faster than us in development.

In the next couple hundred years that civilization discover an entire new way much more efficient than radio and stops using it at all.

We also start using things more efficient than radio almost 20 thousand years ago ourselves so we shut down the ancient technical equipment when we realize they wont receive our ancient radio signal.

They send of a few random radio signals like we have done while they use radio, but noting really aimed at earth so we gain no information from them.
They discover us before they stop using radio and take a guess at what we will be doing 22 thousand years in the future and attempt to send that sort of signal to us. (the signal they now use whatever that is)

We could be playing this sort of game back and forth for a very long time even knowing each other exists.
When the signal they send gets to us, we will probably be using something else being 22 thousand years further technically developed than them.

This is probably a best case scenario that we actually discover a civilization at the perfect stage of technical development and being at the closest average distance to us.

The simple fact that radio unless its directed at something with a big dish and powerful signal doesn't endure the star to star distances, and the fact that radio communications probably only are used a few hundred years for each tech civilization is probably why it's radio quiet.
How few directed powerful signals have we sent?

Radio signals in my opinion are useless for communications with other intelligent species.
If ET's do exist and do chat with each other they are the most patient beings imaginable or chat with a means that doesn't take 1000s of years.


Louis,

The most powerful radio message ever sent was directed at the Magellanic cloud about 100,000 LY away from us and was expected to be receivable with our technology.


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#39 2008-05-08 15:41:47

nickname
Member
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Why No Contact Yet ?

noosfractal,

Probably a good indication we are alone in our galaxy.
Or ET is a lazy bugger. LOL


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#40 2008-05-08 15:48:20

bobunf
Member
From: Phoenix, AZ
Registered: 2005-11-21
Posts: 223

Re: Why No Contact Yet ?

“all parts of the galaxy, many millions of light years away”

The Milky Way Galaxy is only about 100,000 light years in diameter.  Our sun is not more distant than about 70,000 light years from almost all of the stars in our galaxy.

Whatever the time scales I think the analysis supports the statement (in the absence of super-luminal communication): 

“For us to expect to receive transmissions from an advanced ET civilization, the probability of such ETs associated with any given star system must be higher than 1 in 400 million.”

That association could arise from ET originating near the subject star, or from colonizing a celestial body near the subject star.

Bob

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#41 2008-05-08 16:08:46

bobunf
Member
From: Phoenix, AZ
Registered: 2005-11-21
Posts: 223

Re: Why No Contact Yet ?

even if it is slow, every possible star should have been colonized by now:

This is exactly what Fermi pointed out in 1950.

Bob

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#42 2008-05-08 17:14:39

bobunf
Member
From: Phoenix, AZ
Registered: 2005-11-21
Posts: 223

Re: Why No Contact Yet ?

“In the next couple hundred years that civilization discover an entire new way much more efficient than radio and stops using it at all. “

I think this radio disappearing thing is an irrelevancy. 

We don’t know about anything better than what we know about.  A tautology, I think.  One can as easily say, that there isn’t any such thing; or that such a thing would be even more obvious to us than radio; or that such a thing would be super-luminal, which would make for quite a different ballgame.

One can also point out that, even though candle technology has been far exceeded by electric light bulbs, more candles are used today in North American than were used in 1800 when candles were the principle source of illumination.  There’s nostalgia and backwardness which keeps old technologies going for many centuries, if not millennia. 

I don’t see how speculating that radio may go away goes anywhere.  How do you distinguish it from ET going away or never having been there?  Which seems as though it might have a lot more causes; and, maybe, a higher probability. 

I agree entirely that communication is very unlikely if there are only 10 contemporaneously existing advanced ETs in the galaxy with the closest likely to be 22,000 light years away—whether they use radio or not.  The 44,000 year round trip is rather daunting even to beings who live for a few thousand years.  And understanding what technology will exist in 22,000 years on a world 22,000 light years away may be just impossible.

I’d extend that to a hundred advanced ETs.  Even a thousand ETs, with a closest probable distance of 2,500 light years is, I think, probably past the edge of possibility.  Which is why I think any reasonable expectation of communicating with ET implies the existence of more than 1,000 contemporaneously existing advanced ETs in the galaxy. 

If the probability of advanced ETs associated with any given star system were 1 in a million or higher, then there would be 400,000 advanced ETs in the galaxy, and the closest probable distance would be less than 800 light years, and probably two or more within a thousand light years.  Then I think the probability of contact would be high. 

But it seems pretty unlikely that this is the case.

Bob

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#43 2008-05-08 17:19:50

noosfractal
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From: Biosphere 1
Registered: 2005-10-04
Posts: 824
Website

Re: Why No Contact Yet ?

even if it is slow, every possible star should have been colonized by now:

This is exactly what Fermi pointed out in 1950.

Yes indeed.  But this seems to suggest a higher lower bound on the chance that a random star system is inhabited. 

Doesn't your figure suggest that there are only (400e9)(1/400e6) = 1000 habitable star systems?


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#44 2008-05-08 17:22:43

bobunf
Member
From: Phoenix, AZ
Registered: 2005-11-21
Posts: 223

Re: Why No Contact Yet ?

The 1,000 would be an upper bound.  One thousand or less.

Bob

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#45 2008-05-09 05:19:26

nickname
Member
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Why No Contact Yet ?

bobunf,

I think the real question comes down to how odd or normal is life in the galaxy.

If life requires an earthlike world with a big moon and a host of other conditions pretty similar to our solar system, then we could easily be alone in this galaxy.

If life is pretty typical around the galaxy and not so reliant on our type of setup then lots of systems will have life.
Intelligent life forming on any of those places i think will be an oddity just like it was here even with perfect conditions.

When we imagine that 90% of the stars in our galaxy cant support life.
90% of the remaining stars wont have earthlike places.
90% of the remaining total that have earthlike worlds wont be in the right place for an earthlike world.
90% of that total wont have big moons.
90% of that total wont have a perfect mix of gasses/land/water.
90% of them never develop intelligent life.

We probably have another 50 of these to do before we get to a real total of possible places and chances for intelligent life to form on them.

When we start we need a random number on those worlds to see how normal or odd it is for life to develop at all.
If life is very normal then 1 out of 1, if it is an odd event them maybe 1 in 100 or worse.

If life is a very odd event we might not only be alone in this galaxy but alone in the universe.

I think if the galaxy has decent numbers of intelligent species with technical abilities it will still be difficult to communicate with them.
For them to talk with us they will need to be more technically advanced that us and be very persistent in trying to communicate with us.

Long distances might not be a problem if you are a million years more technically advanced than us, because you simply send every type of imaginable signal towards us and wait for a reply.
If radio does indeed become super seeded you send the technical information on radio how to communicate much faster.
Persistence will be needed for sure as the distance increases.


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#46 2008-05-09 07:43:28

bobunf
Member
From: Phoenix, AZ
Registered: 2005-11-21
Posts: 223

Re: Why No Contact Yet ?

“90% of the stars in our galaxy cant support life”

I don’t think this is correct.  The overwhelming majority of stars are main sequence with masses not much larger than our sun or smaller.  Nearly all of these stars will have habitable zones and all will be around for as long as our sun has been, or considerably longer.

"90% of the remaining stars wont have earthlike places."

I don’t think this is correct.  Planetary systems seem to be extremely common.  Even if a planetary system doesn’t resemble ours, the possibility of habitable worlds exists.  The moon of a gas giant is only one of many possibilities.

"90% of the remaining total that have earthlike worlds wont be in the right place for an earthlike world."

In our solar system two such worlds exist.  Between planets and moons, I would think the chance of an Earthlike world in the right place is pretty good.  I don’t think you have any basis for this statement.

"90% of that total wont have big moons."

I don’t think big moons are necessary—especially if some of the abodes of life are satellites of gas giants.

90% of that total wont have a perfect mix of gasses/land/water.

You don’t need a perfect mix.  Earth’s atmosphere has changed from methane to oxygen and life just keep going along.  The Earth could have a lot less or a lot more water and still support life. 

That life arose on Earth almost as soon as the water stopped boiling suggests that biogenesis may be easy and common. 

Don’t be such a pessimist. 

Bob

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#47 2008-05-09 09:58:32

nickname
Member
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Why No Contact Yet ?

bobunf,

80% of the stars in our galaxy are in the central bulge of stars.
To much radiation, to many super novas, to much moving material in that region for life to have a decent chance of being around for at least 2-4 billion years.

Leaving us just 20% of the stars in total,  of that total at least 50% are to big, to small, been around to short a time, or are unstable stars, multiple stars, etc.

Even if we exclude the need for a big moon and just need an earthlike place in the right location with a good mix of gas/land/water and other necessities like a strong magnetic field, we wont have many of them.
1 in a million?
If we indeed do need a big moon, 1 in a billion?
if life doesn't just start naturally on most places it can, 1 in a trillion?
if things need to be almost clones of earth/moon and our solar system and life is an odd event, 1 in 100 trillion?

Life might indeed be a very odd event, on earth it was quite complex as the first form of life.
We find no evidence of a before that step on Earth.
Either life started on Earth as a very unusual event or life somehow made its way here as pretty complex forms in hibernated format.

A close to correct world like Venus or Mars means nothing.
Either we have a world in the perfect place or we don't, not much room for error in Earths orbit to remain as it is.
As little as 1% difference and we freeze or bake.

Moons around gas giants i also think are good places.
I'm not 100% sure many of them will be good places either, some will though.
Radiation, tidal flexing, and many more impacts could be down sides to life on a gas giant worlds moon.
Life on some of the moons going around gas giants, i think so, but would they be good places for long term life development, not so sure. 

I'm no pessimist about other intelligent life in the universe, i just think we are way to optimistic about how many places can host it.
Life i think will be spread around in lots of places, but having the right conditions for life then intelligent life are going to be long odds.

If we are in a galaxy with 10 other technical civilizations then that is great, we will eventually have someone to talk with.

If we are alone in our galaxy then we have a galaxy to spread life to.

If we are alone in the universe we are truly special and should cherish that fact.

Once we get samples back from Mars i think some of the freakishness of life questions will be answered.
Then we can probably take a realistic guess about life in our Galaxy.


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#48 2008-05-09 14:03:37

JoshNH4H
Member
From: Pullman, WA
Registered: 2007-07-15
Posts: 2,526
Website

Re: Why No Contact Yet ?

If, by the far future, we haven't reached a conclusive answer to this question, we could make a planet from metals (astronomical metals, Li+) in the sun, and make a system somewhat similar to earth 4 billion years ago, and wait.


-Josh

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#49 2008-05-09 17:52:14

nickname
Member
From: Ontario, Canada
Registered: 2006-05-15
Posts: 354

Re: Why No Contact Yet ?

noosfractal,

Expanding on your thought about colonizing this galaxy.
What if we are alone in our galaxy but lots of the close galaxies have been colonized by species in those galaxies.

Can we use that same sort of formula for colonizing to other galaxies?
The distances are truly immense to get to the closest other galaxy for any species from any galaxy.

That might be the ultimate barrier, even with very fast travel and very long lived species the distance will still be daunting.


Science facts are only as good as knowledge.
Knowledge is only as good as the facts.
New knowledge is only as good as the ones that don't respect the first two.

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#50 2008-05-09 18:47:25

mork_from_seattle
Member
From: planet_x
Registered: 2008-05-09
Posts: 11

Re: Why No Contact Yet ?

One potential reason for no contact is that we simply havent searched the right place yet.  SETI has only targeted a few thousand stars directly iirc and the deep sky scans are very specific in what frequency they check.  They are often guessing that ET is intentionally broadcasting with powerful transmitters on channels meant to be deduced by us. Lots of guessingi involved.

The Drake Equation is just a guess that generates many values. Anything form 1 to 10k (drakes last guess) ETI civilizations to higher. Assuming Drakes wild ass guess is right that would be one per 20 million stars so we really need a much larger sample before ruling anything in or out.  IIRC the head of the seti@home group suggests that he expects something by the middle of the century.   Or at least that we should be getting sufficient sample sizes by then to make some guesses.

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