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have they found anything?

RecoveringYuppy said:
How could it be technically impossible when it happens naturally? Over the time frames involved the natural velocities of comets and the stars themselves are sufficient for a lot of migration.
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This is what happens when I make other people's arguments: I tend to screw them up. :P

Personally, I think that interstellar travel is quite possible and something that we are likely to partake in at some point in the future.

I guess what I'm suggesting though is that it may be impossible for intelligent lifeforms to send themselves to other stars. But to be honest, when you put it like that I can't really agree with that. So, I will modify my statement:

Interstellar travel may be so difficult to engage in that no technological civilization has engaged in it, regardless of how many there have been to this point in the history of the galaxy.

It may be so difficult that while some civilizations do engage in it, they don't get very far: they travel to one or two other nearby stars, perhaps, and don't go further because they find the rewards aren't worth the effort.

Or it may be that civilizations, once they reach the stage that interstellar travel is possible, simply tend not to be interested in interstellar travel.

Personally the Fermi Paradox does modify my guess as to the probability of ETIs in our galaxy, in such a way that I think it's less likely than I did before I'd heard of the Fermi Paradox. But it certainly doesn't modify it all that much, because there are so many possibilities other than "life is rare" that explain it.
 
Bill Thompson said:
Joe, come out of your fantasy comfort world and answer these questions:

http://www.internationalskeptics.com/forums/showpost.php?p=5421767&postcount=1016
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Asked and answered months ago on this thread. These are basically the Rare Earth arguments.

And your constant insults don't advance the conversation in any way.

ETA: I derive no comfort from acknowledging that we don't know whether or not there are ETIs throughout our galaxy. My position has consistently been just that: we don't know.
 
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Roboramma said:
Interstellar travel may be so difficult to engage in that no technological civilization has engaged in it, regardless of how many there have been to this point in the history of the galaxy.

It may be so difficult that while some civilizations do engage in it, they don't get very far: they travel to one or two other nearby stars, perhaps, and don't go further because they find the rewards aren't worth the effort.

Or it may be that civilizations, once they reach the stage that interstellar travel is possible, simply tend not to be interested in interstellar travel.
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Exactly. Or civilizations don't last long enough to discover everything that is technologically possible. Or they lose interest. Or technologically possible doesn't ever equate with feasible.


Personally the Fermi Paradox does modify my guess as to the probability of ETIs in our galaxy, in such a way that I think it's less likely than I did before I'd heard of the Fermi Paradox. But it certainly doesn't modify it all that much, because there are so many possibilities other than "life is rare" that explain it.
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Given the size of the galaxy, and how spread apart things are, it doesn't alter my view (which is simply we don't know) any more than a glance into my backyard supports the idea that dogs that live beyond my house are rare or don't exist.

Even if there were relatively many ETIs in the galaxy, we wouldn't expect anything we've observed (receiving a radio message, for example) to be different than it is (no more than I have any reason to expect to see evidence of a dog when I glance out the back window).

Absence of evidence where you don't expect there to be evidence is not evidence of absence.
 
amb said:
Jeezus H Christ. This thread is still alive? Has anything changed?
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People will not let go of a faith. Ever.

Science and statistics say that intelligent life is uncommon in the universe and the places where they can exist is getting smaller and smaller the more we learn about the universe. So the SETI apologists are motivated by faith and wishful thinking alone.

Joe will be making posts here for years. He will do this as if doing so will change the facts.
 
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JoeTheJuggler said:
Asked and answered months ago on this thread. These are basically the Rare Earth arguments.

And your constant insults don't advance the conversation in any way.

ETA: I derive no comfort from acknowledging that we don't know whether or not there are ETIs throughout our galaxy. My position has consistently been just that: we don't know.
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What insults?!

And have you read Rare Earth? It is a title for a book. Or you just find the concept on its face value absurd and refuse to dig any deeper?

No, you have not answered the questions.

What I think is you take it at face value and, of course, by name "Rare Earth" is a silly idea. So you use the straw man argument to draw a simple character of the idea so you can dismiss it.

There are other stars. There are other planets. Too many to count (and yet not infinate). So on the face of it, it is silly to think we are alone. And those who do are arrogant. Right? Am I getting your thought pattern down pretty accurately here?

You have yet to write a simple proof that Santa does not exist.

You have yet to write a proof for a negative. Case statements are not logical proofs. Proove that something does not exist.

you have yet to answer the 10 questions. Taking a brush stroke and labeling them as rare earth nonsense is not answering the questions.

Answer the questions. They do not have the term "rare earth" in them at all. They have just as much to do with frozen yogurt as rare earth. It is simple science, math, and guess what else. STATISTICS!! Everything, as it turns out, really is a numbers game.

Accusing me of insulting you is a cheap trick to avoid answering my questions.

Also, you contradict yourself! You insist that Santa does not exist because there is a lack of evidence that he exists. And then you insist that there is ETI because "absence of evidence is not evidence of absence".
 
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Bill Thompson said:
Almost nill.

Seems like a pretty unlikely balancing act to me.

A reoccurring inferno like Venus or a dead dirt ball like Mars I think would be more common. Earth has threaded a proverbial needle by astronomically absurd good luck.

It is not just plate tectonics. It is plate tectonics and them all making big enough volcanoes all at the same time to break the freeze. Otherwise, we would be a snowball planet today. That was winning the lottery in a big way. And I do not think such a thing has happened since. So it is perfect timing as well.

We owe our existance to the fact that there are so many stars. Otherwise, the odds would not be in favor for us to exist.
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What can you show to back up your hunch? Perhaps all that was needed was a few very ashy, Plinian volcanoes that spread ash all over the place.
 
Bill Thompson said:
What insults?!
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Your repeated questions of my credentials when I'm not holding myself out as an authority (my arguments stand on their own and don't rely on my credentials), and your questioning my motivation for participating in this thread.

These things are irrelevant to the discussion.

And have you read Rare Earth? It is a title for a book.
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Yes, and read the thread. We have discussed the book at some length.
 
Bill Thompson said:
And then you insist that there is ETI because "absence of evidence is not evidence of absence".
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This is a complete misrepresentation of my position which I have consistently and frequently stated. My position is that we don't know whether ETIs exist.

And I repeat that in this case, absence of evidence is not evidence of absence.

The assumption that if ETIs exist, then evidence of their existence must be ubiquitous in the galaxy is flawed.

The arguments that every detail about conditions here on Earth are prerequisite to the evolution of complex life is flawed (and typical of the backward thinking of the Fine Tuning argument promoted by Creationists).
 
We have had radio/television/ astronomy signals for around 60 years now, that's a radius of 60 light years in which there are dozens of sun like stars to receive these signals, even in their weakened state a highly evolved civilization would be able to pick them up as would we with the giant radio radar discs that exist around the world that are capable of picking up a signal from a pulsar 100 light years away, yet all there is is silence both ways. Could it be that there's no one there to receive or send back any signals? Perhaps, and this is an old argument, there is only microbial life on most of these if any, life bearing rocky planets?
 
Amb, this is from page 6, and has been reposted at least once already.

Can you not see how it shows your last post to have very little significance to the thread topic? Did you not already see that before you posted it (given that you were involved in this discussion when it came up again on page 17 or 18?
If you really disagree and think that this post doesn't clear up this issue, can you please explain why?

davefoc said:
It is very unlikely that alien civilizations are going to pick up television transmissions according to the table from this site:
http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html

see copy of table in this post:
http://www.internationalskeptics.com/forums/showpost.php?p=3557598&postcount=82

Note the range for UHF television (2.5 AU) and the range for the UHF carrier (0.3 LY). Neither estimate is enough to make it out to the nearest star. They don't list a range for VHF television but FM radio is in the middle of the VHF television band and the estimated range for that is 5.4 AU. Again no where near enough to make it to the first star.

The optimistic ranges for detecting a nearby planet are based on either massively powerful transmitters or highly focused outputs from large transmitters.

The calculations that I made in a previous post suggested that one would need an Arecibo sized antennae with a 250,000 watt transmitter to be able to send a detectable signal to a planet as far away as 150 light years.

This is easily with the capability of earth's technology. The Arecibo antennae has only limited steering capability. I think it is mostly constrained by the direction it is pointing as it rotates with the earth so there are lots of potential targets it couldn't be aimed at. The 250,000 watts could be pulsed so that no where near 250,000 watt of continuous power would be required. But will the powers that be that control enough of earth's resources ever feel like funding a major effort to transmit to unknown alien civilizations?

Post where the calculation was discussed:
http://www.internationalskeptics.com/forums/showpost.php?p=3565450&postcount=94

I think the most likely intentionally produced electro magnetic radiation produced on the earth today that could be detected by an alien civilization would be from radars. These are focused and some of them are very powerful. I notice that the table lists the range of a particular weather radar as .01 light years. That doesn't validate my guess because it lists the range of a UHF carrier as .3 light years but I suspect that other radars would do better. Military radars might do much better.

But even if the ranges of military radars are much greater than what is listed for the weather radar in the table, the ranges are still probably much too small to get much beyond the nearest stars.

In another post I linked to an article discussing the feasibility of a laser transmitter to reach stars. If the powers that be wanted to dedicate some resources to this idea the authors suggest that we might hit a 1000 light years with a currently feasible optical laser. I think that bumps the stars for which a signal might be detected from about a 1000 that lie within 100 light years to about a 100,000 that lie within a 1000 light years.

The article on the possibility of optical SETI:
http://seti.harvard.edu/oseti/tech.pdf
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amb said:
We have had radio/television/ astronomy signals for around 60 years now, that's a radius of 60 light years in which there are dozens of sun like stars to receive these signals, even in their weakened state a highly evolved civilization would be able to pick them up
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No they couldn't, and this was covered long ago.

ETA: I also recall that I asked if you're going to assume that magic technology MUST exist if any ETIs exist (and since it doesn't, they don't), why not extend your argument and claim that there are no other ETIs in the entire universe? After all, if you presume magic technology MUST happen, then why not some serious magic technology, like instantaneous teleportation or a panopticon (capable of seeing and playing back all events throughout all of space and time)?

There's also no technology that would let an intelligent civilization thousands of light years away detect the first time humans used fire.
 
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By the way, another explanation for the lack of evidence of ETIs is the possibility that they don't want us to see evidence of their existence. Again, if you're going to assume every technology that is possible must have been developed and used millions of years ago, then why not allow for something like the ability to keep a relatively primitive civilization in the dark?
 
JoeTheJuggler said:
No they couldn't, and this was covered long ago.

ETA: I also recall that I asked if you're going to assume that magic technology MUST exist if any ETIs exist (and since it doesn't, they don't), why not extend your argument and claim that there are no other ETIs in the entire universe? After all, if you presume magic technology MUST happen, then why not some serious magic technology, like instantaneous teleportation or a panopticon (capable of seeing and playing back all events throughout all of space and time)?

There's also no technology that would let an intelligent civilization thousands of light years away detect the first time humans used fire.
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That's nonsense. A civilization only one thousand years ahead of us would seem as magic to us. Who knows what future discoveries will bring, what new form of power using the sun itself, what powerful transmitters and receivers, like you keep saying, we at this stage do not know.

That article in Wiki says we may have to revise our estimates of alien lifeforms in the cosmos because of the negative results which are not likely to improve in the foreseeable future.
 
amb said:
That's nonsense. A civilization only one thousand years ahead of us would seem as magic to us. Who knows what future discoveries will bring, what new form of power using the sun itself, what powerful transmitters and receivers, like you keep saying, we at this stage do not know.

That article in Wiki says we may have to revise our estimates of alien lifeforms in the cosmos because of the negative results which are not likely to improve in the foreseeable future.
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There is a big difference between their technology seeming like magic and their technology being capable of any magical thing you can imagine.

If, for instance, you encountered some technologically primitive people and found that one of them was suffering from a disease treatable through modern medicine, and treated them, they might then expect that you could bring their dead friends back to life, but regardless of your technology seeming like magic, it still has limits, and you wouldn't be able to help them there.

Similarly, whatever technological advances are possible, and I'm sure there are many that we haven't even conceived of yet, there are also some which simply are not. You seem to be suggesting that you know which is which when you say that they will necessarily be able to detect our (very faint) signals.

As to your previous post, I haven't finished reading the link, but I'll try to get to it. :)
 
Roboramma said:
There is a big difference between their technology seeming like magic and their technology being capable of any magical thing you can imagine.
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Well said.

And on top of that, amb's argument not only depends on any magical thing one can imagine being technologically possible, it depends on the assumption that whatever is possible absolutely will happen.

The argument depends on the assumption that such things as interstellar travel, colonization/exploration of the galaxy are so inevitable that the lack of ubiquitous evidence of this sort of thing leads to the conclusion that ETIs don't exist.
 
JoeTheJuggler said:
This is a complete misrepresentation of my position which I have consistently and frequently stated. My position is that we don't know whether ETIs exist.
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And how is that any different from saying we do not know if Santa exists?

And, besides, aren't you saying YOU don't know if ETI exists? Shouldn't you speak for yourself here?
 
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Bill Thompson said:
And how is that any different from saying we do not know if Santa exists?

And, besides, aren't you saying YOU don't know if ETI exists? Shouldn't you speak for yourself here?
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Well, in the general sense of it's saying we don't know something exists, it's the same.

In the specific sense of why he's saying it, it's very different.

Why is it different? Because there is a great deal of evidence that there is no Santa, whereas there is very little evidence that there are no ETIs.

To put that slightly differently: of the two possibilities:
a) there is no santa
b) there is a santa
"a" is the far more parsimonious conclusion.

Of the two possibilities:
a) there are no ETIs
b) there are ETIs
there is some evidence that leads us toward "a", and some that leads toward "b", but neither has any particularly compelling evidence, so the best we can do is to say, "we don't know".

Now, personally, when I examine the evidence, I think that there being some ETIs in the universe, even in our galaxy, is more likely than not, but I don't find that conclusion to be all that solid, and would not be all that surprised if there were none. That is, I think the evidence leans toward "b", but not particularly strongly.
Joe may be more in the middle than me, which I think is an entirely reasonable position. Others look at the evidence and think it leans more toward "a", which I again consider to be quite reasonable. Those, however, who say that "a" is assured are, in my opinion, fooling themselves, and so far have failed to make a strong case.

As to amb, I'm still not sure where he sits, as sometimes he seems to say that "a" is almost certain, whereas other times he says that "b" is true, but the number of ETIs is certainly very small. I have none of that certainty, I wouldn't be surprised if there were a great many ETIs, nor if there were very very few of them.
 
amb said:
We have had radio/television/ astronomy signals for around 60 years now, that's a radius of 60 light years in which there are dozens of sun like stars to receive these signals, even in their weakened state a highly evolved civilization would be able to pick them up as would we with the giant radio radar discs that exist around the world that are capable of picking up a signal from a pulsar 100 light years away, yet all there is is silence both ways.
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OH FOR ****'S SAKE, are you deliberately being daft? This has been addressed NUMEROUS times, and Robo just quoted the specific post. Even with an Aericibo array on A. Centaruri, our civilization is UNDETECTABLE. That's only a measly 4 light years away! Pulsars and stars are totally different... *sigh* It's like arguing wiht a creationist, same old tired canards repeated over and over again. I can see why Joe would accuse you of that mentality.

By the way, I used to think that anyone wihtin 60 light years could detect us, but then that nasty inverse square law showed me the folly of that train of thought and I had to re-evaluate it. Why have you not done so in the faceof physics?
 
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