have they found anything?

[JoeTheJuggler]

This is one of those rare threads that goes on and on without an obviously crazy person to drive it.

I wouldn't say amb is "obviously crazy" but he definitely goes against almost every one of your "everybody" statements:

Everybody seems to agree that given the vast number of stars in a galaxy and the vast number of galaxies that some form of sentient life probably exists outside the earth.

Amb has followed the Rare Earther line and said that it is almost certain that we are alone in the galaxy and there may only be a dozen or so ETIs in the entire universe.

Everybody seems to agree that as of yet there is no probative evidence for a visit to Earth by sentient beings from outside the Earth.

I agree. This wasn't a UFO thread.

It seems that nobody could disagree with amb's overview of the reasons why sentient life hasn't been detected on the Earth:

That wasn't amb's words. He was quoting (without tags or quotation marks) from a Wiki article. His comment on it was, "Doesn't this sound like a conspiracy of Governments to silence on the Ufology subject?" In other words, he was disagreeing with the quote you offered.

ETA: Amb was equating the Wiki quote you quoted with UFO CTers. He was dismissing refutations of the Fermi paradox by saying it's the same as people who think we're being visited by space aliens.

I think everybody would agree that Fermi's paradox, that while interesting, does not provide a definitive answer as to whether there is sentient life that is within range of contact from the earth.

Again, amb has steadfastly maintained that Fermi's paradox is strong proof that ET intelligence does not exist.

So what is the issue that people disagree about?

Mostly, amb espouses the quasi-religious arguments given in The Rare Earth hypothesis. While amb is not a creationist, the arguments he supports in the Rare Earth position are just as backward as the Fine Tuning arguments. The Rare Earth position states that every rare or unique feature about the Earth is prerequisite to complex life.

Is it that some people think that sentient life in the galaxy is rare and some other people think it is very rare? Is it that some people think the chances of contact with alien sentient life on earth is low and some people think it's somewhat more likely than that?

There's rare and then there's rare--a point I've made time and again. (If something happens in 1 per 1 million stars, then it still would happen some thousands of times in our galaxy alone.) I believe things in the universe (even within our galaxy) are so spread out in space and time that it's unlikely we'll ever encounter another radio-technology using civilization.

However, I don't think there's anything unique about the Earth. The same laws of physics and chemistry that apply here apply throughout the cosmos. The same amount of time that has elapsed here has elapsed elsewhere.

My gut feel about the situation is that human beings will never detect another civilization with sentient life. This is based on my view that sentient life is rare and that there are far too few places where sentient life seems possible within a range where communication is possible to provide much of a chance of contact. Is this the notion that some people are disagreeing with?

No. The point of disagreement is the Rare Earth business. Amb has also made the false dichotomy that either complex life must be ubiquitous, or it is virtually non-existent. IIRC, he also made the false dichotomy that either we are unique in the galaxy, or there must be a god, though I can't remember quite how that line of thinking went.

In fact, the limits of what SETI could detect and the limits of a self-replicating probe have been pointed out as a good reason not to extrapolate the non-existence of ETI based on a lack of results.

Someone even posted a graphic that showed the tiny sphere within the galaxy within which we have even been able to detect extra-solar planets at all. I pointed out that we know almost nothing about most of them. About all we can say about extra solar planets is that whenever we've used a technology to detect them with certain characteristics (size, alignment with us relative to their star, etc.), we have found them in abundance.

If one is looking for an argument from authority that I am wrong one needs to look no further than Mr. Drake himself who seems to have gotten more enthused of late about the possibility of contact. My own horribly amateurish take on Mr. Drake's thoughts on this is that he underestimates the importance of data that has been found since he first published his equation that suggests that sentient life is even less likely than he originally estimated and that he exaggerates the possibility of sentient life on non-earth like planets that have been detected since he published his equation originally.

A more or less recent Drake article was cited fairly early in this thread where he said what you've summarized. I believe he now thinks his famous equation would give an underestimate. From what I read, the main reason was that he left out the possibility of life in situations other than an Earth-like planet around a single main sequence star. One example I recall was the possibility of life arising in the twilight zone of a tidally locked planet the right distance from a red giant. Or possibly interstellar planets or some such.

At any rate, my position has always been that we don't know, but there's no reason to suspect there is anything unique about the Earth. The universe is really really really big, so it would surprise me if complex life forms didn't exist elsewhere. But we don't know. Not knowing is not the same thing as knowing it doesn't exist.

 

[davefoc]

Thanks for the response JTG. I was frankly a bit confused by exactly what amb meant in the post where he quoted Wikipedia. I thought this statement:

Doesn't this sound like a conspiracy of Governments to silence on the Ufology subject

was completely tongue in cheek. If this wasn't the case then I have really misunderstood some of amb's intent.

Based on your reference I read through the Wikipedia article on the Rare Earth Hypothesis. At least to my mind, the rare earth hypothesis does not seem to be principally a supernaturally influenced idea. That is not to say that amb's use of it wasn't.

 

[LarianLeQuella]

I don't think AMB sees the rare earth hypothesis as a supernaturally influenced. But rather a requirement for intelligent life to develop (i.e. a large moon, at the right distance, the right size, mamilian animal types, asteroid impacts, etc. etc. etc. describing OUR planet). While I and many others contend that with our ONE datapoint, we can't say. The sheer amount of space and incredibly rich possibilities of evolution suggest that earth is just one of a myriad of possibilities that can arrive at intelligent life. We know that the rare earth has a 100% probability of intelligent life, because we're here, but to make assertions beyond that is way too "human-centric" as I put it.

Clear as mud?

 

[amb]

It seems that this thread is been turned into a witch hunt for me. I will not go over what has been already discussed here in the past, as that would be a waste of time.
Anyway, my argument has always been that the cosmos is more than likely teeming with life. Microbial, not intelligence at our level or beyond. For the record, I'm a militant atheist.

 

[davefoc]

It seems that this thread is been turned into a witch hunt for me. I will not go over what has been already discussed here in the past, as that would be a waste of time.
Anyway, my argument has always been that the cosmos is more than likely teeming with life. Microbial, not intelligence at our level or beyond. For the record, I'm a militant atheist.

That was very much not my intent and my apologies if that has been the result. I just went back and reread a few of the last pages to see if I could understand this thread a tad better. I couldn't. It looks to me that AMB believes that sentient life is a very rare phenomena and others believe it is somewhat less rare. And everybody agrees that we don't know and probably won't ever know. Seems like a reasonable, well defined dispute that centers mostly on the process by which we combine a few facts and our biases to make judgments about the answers to questions for which the data is insufficient to allow us to determine a pure fact based answer. No harm. No foul.

But I also reread something that I wrote and was somewhat embarrassed to see that I had made a stupid arithmetic error:

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.

If the range is increased by a factor of ten the volume contained within the range is increased by a factor of 1000 (10³) so bumping the range by a factor of 10 should increase the number of stars from about a 1,000 to about a 1,000,000. Sorry for the mistake.

 

[JoeTheJuggler]

Based on your reference I read through the Wikipedia article on the Rare Earth Hypothesis. At least to my mind, the rare earth hypothesis does not seem to be principally a supernaturally influenced idea. That is not to say that amb's use of it wasn't.

Actually, I think amb's use of it is less religiously-motivated than the originator of the ideas in it.

The origin of most of the arguments used in Rare Earth was Guillermo Gonzales, professor of astronomy at the University of Washington. He is a public Creationist who admits that his theological views motivate his science. (I think Rare Earth authors Ward & Brownlee, like amb, were unaware that they were being fed a religiously-motivated argument. Gonzales correctly points out that his religious motivation is not a secret.)

The arguments themselves, as I mentioned, are often very much like the Fine Tuning argument. They take as many characteristics of the Earth (extremely large moon, proximity of a Mars-like planet and a Jupiter-like planet, etc.), take all of those characteristics as prerequisites for complex life, then ask, What are the odds of this exact constellation of characteristics happening elsewhere in the galaxy?

 

[JoeTheJuggler]

It seems that this thread is been turned into a witch hunt for me. I will not go over what has been already discussed here in the past, as that would be a waste of time.
Anyway, my argument has always been that the cosmos is more than likely teeming with life. Microbial, not intelligence at our level or beyond. For the record, I'm a militant atheist.

Of course your opinion on the presence of microbial life is not the topic of the thread or the point of contention.

You have been arguing in favor of the Rare Earth "hypothesis" that uses speculation to suggest that we are likely alone in the galaxy. You have used the Fermi Paradox and lack of a "hit" from SETI to support your contention that no ETI exists in our galaxy.

I accept that you are an atheist, but I think you have been using arguments that were originated for religious motivations.

 

[JoeTheJuggler]

That was very much not my intent and my apologies if that has been the result. I just went back and reread a few of the last pages to see if I could understand this thread a tad better. I couldn't. It looks to me that AMB believes that sentient life is a very rare phenomena and others believe it is somewhat less rare.

Again, there's rare and there's rare. AMB has said he thinks we are alone in the galaxy and that there are no more than a dozen such intelligences in the entire universe.

And everybody agrees that we don't know and probably won't ever know. Seems like a reasonable, well defined dispute that centers mostly on the process by which we combine a few facts and our biases to make judgments about the answers to questions for which the data is insufficient to allow us to determine a pure fact based answer. No harm. No foul.

AMB has argued that if ETI existed in our galaxy it must have existed for millions of years and evidence of it would be ubiquitous in the galaxy (basically an argument based on Fermi's Paradox). Since such evidence does not exist, there is no ETI. (I've pointed out repeatedly that that argument rules out our own existence since we are largely undetectable by our own technology beyond our own solar system.)

He has also argued, following the Rare Earthers, that a Mars-like planet is necessary for complex life (because, apparently, abiogenesis could have happened on Mars and then Mars meteorites seeded the Earth, but abiogenesis couldn't happen on an Earth-like planet where complex life might evolve).

He has also argued that a Jupiter-like planet is necessary to protect the Earth-like planet from collisions with asteroids or whatever. (I've pointed out that not only isn't it certain that Jupiter affords such protection, even if it did, one could speculate as well that complex life would arise earlier if you hit the ecological "reset" button more frequently.)

He has also argued that a large moon like ours is extremely rare (based on guesswork) and essential for complex life since it prevents Earth's rotational precession from resonating with orbital precession. (Again, no evidence that the gradual climate change such a resonance might cause would make complex life impossible--nor, for that matter, that it might not actually be more favorable to the evolution of complex life!)

 

[JoeTheJuggler]

The other very quasi-Creationist argument AMB has used is the notion that intelligence is an all-or-nothing thing, and that only one species on Earth has ever evolved intelligence.

He even argued that cetaceans arose much earlier than primates, but how come cetaceans never reached higher levels of intelligence? Of course, cetaceans and primates arose at roughly the same time--actually the order primata is probably a little bit older than cetacea.

 

[amb]

So you still believe that if all homo sapiens were to die out tomorrow, some other Earth species will develop our level of intelligence? Maybe an ant? Perhaps a Bonomo?

Darwinian evolution argues that far from intelligence been a given, it's entirely a random event as espoused by Richard Dawkins and Stephen Jay Gould. If this is correct, then a feature of life such as intelligence is purely a chance phenomenon, exceedingly unlikely to arise elsewhere independently.
That is not to say that animal life is only likely to have appeared on Earth. There may well be a few planets out there with such life. What I'm saying is intelligence at our level is exceedingly rare. A probability of 0.

Returning to Darwinian evolution. The concept of alien life is, therefore fundamentlly anti- Darwinian.

 

[JoeTheJuggler]

So you still believe that if all homo sapiens were to die out tomorrow, some other Earth species will develop our level of intelligence? Maybe an ant? Perhaps a Bonomo?

A bonobo?

At any rate, that's not the way evolution works. There's not a pre-set goal or end. However, since homo sapiens is not the only organism to have evolved intelligence, your position that we are the only intelligence ever to have evolved on Earth is simply factually wrong. As with many characters, intelligence exists on a continuum in a great many organisms. We are the most intelligent. If humans were to go extinct tomorrow, another organism would be the most intelligent.

Darwinian evolution argues that far from intelligence been a given, it's entirely a random event as espoused by Richard Dawkins and Stephen Jay Gould. If this is correct, then a feature of life such as intelligence is purely a chance phenomenon, exceedingly unlikely to arise elsewhere independently.
That is not to say that animal life is only likely to have appeared on Earth. There may well be a few planets out there with such life.

Have you read the Darling book? He makes a strong case that convergence is much more common than you seem to think. Convergent evolution is indeed part of conventional theory of evolution by natural selection. Certain characters and structures come up over and over.

Returning to Darwinian evolution. The concept of alien life is, therefore fundamentlly anti- Darwinian.

This is an example of the kind of statements you make that make me wonder whether or not you are really a creationist. If alien life is "fundamentally anti- Darwinian" what about life on Earth? Do different rules apply here? Are you not saying that humans couldn't possibly have evolved? It really sounds like a Creationist argument.

As an aside, I reject the terms "Darwinian" and "anti-Darwinian" because they are ambiguous and are frequently used by Creationists to mischaracterize concepts in biology. Even using the term as you do suggests that Darwin was some sort of infallible cult leader, rather than merely a scientist. At best, it's an ambiguous term.

What I'm saying is intelligence at our level is exceedingly rare. A probability of 0.

Davefoc, do you see what I mean now? He's using the term "rare" but is actually claiming to know that we are unique.

Or maybe amb doesn't understand what a probability of zero means.

 

[Puppycow]

IMO we could speculate forever and never get anywhere.
I suspect that the distance scales involved mean that we would not have detected alien life yet even if it was present on a planet around Alpha Centauri. Even Alpha Centauri is farther away than human imagination can comprehend.
Because we cannot even see earth-size planets. We can only detect Jupiter-size planets that orbit closer than Mercury by seeing a star wobble slightly. We cannot actually directly see the planets. So even if there was life like us on every other star system, we might be none the wiser.
Which is to say, let's keep developing telescopes that can see farther with better resolution.

 

[JoeTheJuggler]

IMO we could speculate forever and never get anywhere.
I suspect that the distance scales involved mean that we would not have detected alien life yet even if it was present on a planet around Alpha Centauri.

I agree.

We can only detect Jupiter-size planets that orbit closer than Mercury by seeing a star wobble slightly.

This is not true. We have already detected both gas giants and "Earth-like" planets in various orbits. List of extrasolar planets.

ETA: Also a few extrasolar planets have been found by direct imaging.

The Kepler Mission will probably detect dozens if not hundreds of Earth-like planets in the habitable zone. It's a time consuming process, though. (You basically have to "see" the planet transit the star more than once--so you have to look at these stars a long enough time to measure the changes. In Kepler's case, it's observing fluctuations in the brightness of the star due to the planet eclipsing the star relative to us rather than wobble.)

But your broader point is true. Even of the extra solar planets that we have detected, we know relatively little about them (see list linked above).

 

[amb]

All creatures great and small have a certain level of intelligence, enough for them to survive in a world where the fittest and most adaptable only have and will survive.
Only man has far exceeded an intelligence level required for survival. This has taken 4 billion years, half the lifetime of the sun's stable period. In around another billion years, the Earth will no longer be able to sustain life of any kind unless some animals evolve to be able to withstand enormous variation of temperature.
Someone mentioned Alpha Centauri, at around 5 light years away this star system which by the way is a binary system, therefore quite impossible for a life bearing planet to evolve because of the chaos of gravity between the two stars would make a orbiting planet uninhabitable even by the most primitive of lifeforms. But lets suppose that somehow intelligence developed there at around the same time as here. That gives five years for any radio signals to have arrived here. I'm all ears, yet I hear nothing.
The fact that our radio signals have been traveling into space since Marconi invented the radio transmitter, hundreds of light years, enough time for a nearby neighbor to learn of our existence. We wait with bated breath for a responce.

 

[Puppycow]

But how powerful a radio telescope would be necessary to pick up radio signals from earth at a distance of 4 or more light years assuming the transmitter and receiver are not pointed at each other?

 

[JoeTheJuggler]

But how powerful a radio telescope would be necessary to pick up radio signals from earth at a distance of 4 or more light years assuming the transmitter and receiver are not pointed at each other?

A telescope 100 times more sensitive than Arecibo would not be able to detect broadband signals beyond even our own solar system.

So a civilization just like our own could exist even around the nearest stars and, at this point, still be undetectable to us unless they directed a signal at us (and we were listening to that spot in the sky exactly when that signal arrived).

 

[JoeTheJuggler]

All creatures great and small have a certain level of intelligence, enough for them to survive in a world where the fittest and most adaptable only have and will survive.

Sorry, but plants which have no nervous systems do not have anything like "intelligence". Nor do amoebas, bacteria, fungi, etc.

Only man has far exceeded an intelligence level required for survival.

That's not true.

This has taken 4 billion years, half the lifetime of the sun's stable period.

That's also not true.

The fact that our radio signals have been traveling into space since Marconi invented the radio transmitter, hundreds of light years, enough time for a nearby neighbor to learn of our existence. We wait with bated breath for a responce.

See Puppycow's question and my answer. A civilization with technology equal to our own would not be watching I Love Lucy 50 light years away. This point was covered very early in this thread.

 

[amb]

We seem to be going over old posts. I have nothing to add to this thread, and it seems neither have you.
One idea I may have never put forward is that if there are intelligences out there like us or vastly more so, that makes physicist Professor Paul Davies correct in his theory that the universe is tuned for life, tuned for intelligence by a designer. Davies has won a Templeton prize for his ideas.
I reject that idea completely. We are here only by a giagantic fluke of the laws of nature.
I repeat for the hundreth time. If homo sapiens were to suddenly become extinct, there will never be a species like us again on this planet.
Pretending that the history of this planet was a twenty four hour clock, homo sapiens appeared at 11.58 PM.

 

[JoeTheJuggler]

One idea I may have never put forward is that if there are intelligences out there like us or vastly more so, that makes physicist Professor Paul Davies correct in his theory that the universe is tuned for life, tuned for intelligence by a designer.

No it does not.

Even if we learn someday that intelligence is relatively common in the universe, it does nothing to argue in favor of a tuner or a designer. Physics, chemistry and biology (evolution) is sufficient to account for it.

Your argument that either a theological argument is correct or there cannot be other intelligences in the universe is fallacious.

 

[arthwollipot]

Joe, did you miss the bit where amb said "I reject that idea completely"?