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have they found anything?

JoeTheJuggler said:
It's the same thing. Also the same with Santa Claus. If Santa Claus were true, predictions made by the Santa Claus theory would come true consistently, but they don't. For example, if Santa Claus were real, we predict sleigh tracks on the roof and gifts appearing under the tree that no normal human put there.
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Finally we are getting somewhere. Santa made the tracks disappear.
Predictions? Santa does not follow your schedule, he has his own schedule. The ways of Santa are mysterious.

You say that if you make a prediction about Santa and it does not come true, then he does not exist? Dude, EVERY prediction of if and when we would get a signal from SETI@HOME has been wrong!!
 
Bill, everything you're raising has been answered in this thread already.

You're entirely too hostile for conversation.
 
Bill Thompson said:
Joe, I ask you to provide proof that Santa does not exist. I am still waiting.
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Not to step on Joe's toes here, but the entire fable of Santa is well know in its origins and can be traced through all the numerous permutations that finally arrived at the current fable. Also, specific statements regarding Santa are patently false. We have explored the surface and underside of the North Pole quite extensivelly, and found no workshop. The stories indicate that one should be there, but it's not, so the story itself is false.

After that, people invoking magic or whatnot to desperately try to keep the story alive are grasping at straws.

Kind of reminds me of other stories that people cling to.

So far, no prediction or statement about ETI having any measurable effect on us has been made, thus the jury is still out.
 
LarianLeQuella said:
Not to step on Joe's toes here, but the entire fable of Santa is well know in its origins and can be traced through all the numerous permutations that finally arrived at the current fable. Also, specific statements regarding Santa are patently false. We have explored the surface and underside of the North Pole quite extensivelly, and found no workshop. The stories indicate that one should be there, but it's not, so the story itself is false.
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That is not a proof. Prove that he does not exist. Saying that there are fables that can be traced back regarding Santa does not prove that he does not exist.

ET and ETI and ETL all have fables too that date back longer than the fables regarding Santa.

By the way, people thought Mountain Gorillas were fables too once. Saying that something is based on fables does not prove that it does not exist.

Also saying that "Santa is not there" is not proof that he does not exist!! You could fly over the North Pole and say "see, he is not there" to someone and they could easily just say that Santa knew you were coming and he is hiding.
 
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arthwollipot said:
Wait - is Bill actually asking someone to prove the nonexistence of something?
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No, he's suggesting that those who think that the probability of extraterrestrial intelligence elsewhere in our galaxy is high are doing so.

Basically he says, "I can't prove that ETIs don't exist just like you can't prove that there's no Santa Claus, but the lack of evidence for them suggests that they don't exist, just like the lack of evidence for Santa Claus suggests that he doesn't exist."

Of course, there's a problem with that. The problem with Santa Claus is that we are lacking evidence for his existence that we would expect to have if he existed. That's not the case with ETIs.
 
Bill Thompson said:
Joe, I ask you to provide proof that Santa does not exist. I am still waiting.

You say that there is no Santa because there is no evidence.
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We know there is no Santa because there is no evidence where we would expect to find it.

I remember when I was about 5 years old, I wondered if Santa was real. I knew it was possible that my parents were simply putting the presents there for me, so I decided that I'd have to wait until I was older and had moved out on my own to see if Santa brought presents for me.
Of course, long before that I had other evidence of Santa's non-existence, but even as a five year old I could think of a test for the existence of not of Santa.

Regarding ETI, what particular test are you suggesting has been done and found that the evidence showed that ETI doesn't exist?
 
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Roboramma said:
No, he's suggesting that those who think that the probability of extraterrestrial intelligence elsewhere in our galaxy is high are doing so.

Basically he says, "I can't prove that ETIs don't exist just like you can't prove that there's no Santa Claus, but the lack of evidence for them suggests that they don't exist, just like the lack of evidence for Santa Claus suggests that he doesn't exist."

Of course, there's a problem with that. The problem with Santa Claus is that we are lacking evidence for his existence that we would expect to have if he existed. That's not the case with ETIs.
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Thanks for summarising. I've only been skim-reading this thread for some time now.
 
Bill Thompson said:
Ice reflects light. The sea does not as much. Each one hundred thousand years we have an ice age and each one is a roll of the dice. If the ice sheet advances past where St. Louis is, we have crossed the point of no return.

The idea of "snow ball earth" was discovered by a Russian scientist and Carl Segan when they crunched the numbers of what an all out nuclear war would do to the earth. If the sun was blocked out and if temperatures went down far enough for long enough we would hit a tipping point.

The idea of snow ball earth was made before it was discovered that it had once really happened.

Also, it should be like that right now if not for a stroke of luck.

It was dumb luck that volcanic activity broke us from the "snow ball earth" according the discovery channel episode. If we did not win that proverbial lottery, we would be locked in ice.

Like I said, ice reflects light. The sea does not as much. Each one hundred thousand years we have an ice age and each one is a roll of the dice. Glacier evidence on the equator now proves that during one of those ice ages, the ice sheet advanced past the point of no return and the advancing ice sheet form the north and the south met at the equator.

Luckily we have tectonic plates. Luckily they just happened to make enough volcanoes all at the same time (after about 30 million years of being an ice planet, as I recall) and broke the snowball earth.

The Earth was young then. Somehow microbial life existed and survived but more complex life would be impossible to evolve.
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OK, fine. Without plate tectonics we would not have multi-cellular life. Then, what do you suppose is the probability that a planet of our size will be sufficiently tectonically active to escape a snowball event?

That would be a function of our internal temperature, I presume. Our internal temperature depends on several things:

- The raw size of the planet, providing sufficient materials described in the next three points and a sufficiently insulative mantle blanket to promote an active interior.
- The initial kinetic/potential energy available to convert to heat, which, if our size is constant would be roughly the same.
- The proportion of iron available, which, while falling towards the core in the "iron catastrophe", also gives up its potential energy into heat.
- The amount of uranium, thorium and other radioactive species/isotopes available to decay and this give up heat.

I don't see how tectonics would be a low probability occurrence for any given rocky planet of our general size placed within a liquid water domain. Both the freezing and the melting appear to be limited run-away thermal processes, and therefore inevitable if the triggering conditions are available, therefore I don't see why the snowball earth would be an ultimate peril for multi-cellular life. Indeed, it would have to be held in abeyance for perhaps 50 million years, that could well be enough to start multicellular creatures. It was only about 40 million years from the end of the Marinoan snowball to the first appearance of multicellular creatures (sponges, jellyfish, nidarians) in the Ediacarian period.
 
The arguments put forward of why ET is not yet here is weak in a galaxy that is up to 13 billion years old. Every possibility is possible in such a vast galaxy with possibly up to 400 billion stars. At least some of these stars would have sprouted a life bearing planet perhaps billions of years ago. And at least some of a nearby advanced planet perhaps a million years more advanced than us should by now have discovered us. They haven't which could mean we are alone in this part of the galaxy at least, or we are one of the first.
 
amb said:
The arguments put forward of why ET is not yet here is weak in a galaxy that is up to 13 billion years old. Every possibility is possible in such a vast galaxy with possibly up to 400 billion stars.
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Every possibility is possible? Well, yeah.

But impossible things aren't. And things which are improbable enough remain improbable even after many billions of years.

It really is possible that interstellar travel simply doesn't happen. It might be technically impossible (there was a thread recently in which quite a few people argued just that).

At least some of these stars would have sprouted a life bearing planet perhaps billions of years ago. And at least some of a nearby advanced planet perhaps a million years more advanced than us should by now have discovered us.
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That's the part that you need to justify. What makes you think that they would necessarily have the means and the motivation do to so?
 
Roboramma said:
It really is possible that interstellar travel simply doesn't happen. It might be technically impossible (there was a thread recently in which quite a few people argued just that).
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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.
 
Roboramma said:
No, he's suggesting that those who think that the probability of extraterrestrial intelligence elsewhere in our galaxy is high are doing so.

Basically he says, "I can't prove that ETIs don't exist just like you can't prove that there's no Santa Claus, but the lack of evidence for them suggests that they don't exist, just like the lack of evidence for Santa Claus suggests that he doesn't exist."
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Kind of. I pointed out that in this case (existence of ETIs) the absence of evidence is not evidence of absence, to which Bill said that you can't logically prove a negative. I pointed out that as the statement was worded, it's wrong and gave several examples of logical proofs of negatives. I even indicated that I was aware that what he probably meant was that it's difficult to prove the non-existence of something. (The "there are no black swans" issue--it's easy enough to disprove, but how do you prove it?)


Of course, there's a problem with that. The problem with Santa Claus is that we are lacking evidence for his existence that we would expect to have if he existed. That's not the case with ETIs.
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Exactly. The argument for the non-existence of ETIs based on lack of evidence assumes that existence of an ETI must be ubiquitous in the galaxy. There are any number of reasons why they might not be.

It's not that we have to prove which if any of these (the numbered points I've made on this thread for nearly a year now) is true. It's enough that any one of them is possible to show that the evidence of ETIs (if they exist) need not be ubiquitous. Thus, the absence of evidence in this case is not evidence of absence.

The analogy I've been making is this situation: I've got a dog here in the house next to me, but when I glance out the window to my back yard, I don't see any evidence of extra-in-my-house dogs. It's absurd to claim therefore that there are no dogs anywhere else in the world other than the one here in my house.

Proving the non-existence of Santa Claus or phlogiston (surely we have!) is beside the point anyway. No one is claiming you've got to have proof of the non-existence of ETIs.

I'm just pointing out that the argument for the non-existence of ETIs based on the lack of evidence is not valid. Again, we are an intelligent civilization, and evidence of our existence (whether self-replicating probes, galaxy-wide colonization or whatever) is not ubiquitous. Another civilization contemplating our existence and using your reasoning would incorrectly conclude that we do not exist. Yet here we are.

Also the Rare Earth arguments have been thoroughly debunked, and the connection of these arguments to Creationist/ID proponents has been shown. That's why the backward thinking that every aspect of conditions here MUST be prerequisite to complex or intelligent life is so similar to Creationist/ID and Fine Tuning arguments.
 
Roboramma said:
It really is possible that interstellar travel simply doesn't happen. It might be technically impossible (there was a thread recently in which quite a few people argued just that).
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Also, one of my numbered points, it might be technically possible but for other reasons something no civilization ever ends up making use of. (Or technically possible but something no civilization ever discovers.)

Again, the argument amb and Bill have been pushing rests on the assumption that it's not only technically possible but absolutely inevitable that an intelligent civilization would discover it and be motivated to exploit the technology and make evidence of their existence ubiquitous throughout the galaxy.

There are all sorts of possible explanations why this assumption doesn't have to be true. (And for the argument to work, the assumption must be true.)

It could be technologically impossible (and rather than address FTL, interstellar travel, self-replicating probes or ANY specific formulation of Fermi's Paradox, I'm referring to the very general proposition that an ETI would make evidence of its existence ubiquitous in the galaxy).

It could be possible, but no civilization lasts long enough to discover it.

It could be possible and civilizations could last long enough, but it could be that civilizations at that level always (or even usually) lack the motivation to do it.

It could be possible and civilizations could last long enough and have the motivation, but the technology could be economically impractical.

It could be that all those things are in place, but evidence doesn't last long enough to remain ubiquitous throughout the galaxy for any length of time. (In my dog analogy, what if a dog had just walked through my back yard a few minutes before I looked out? What if a civilization had colonized all of the universe, but then abandoned some bits of it a mere 100 million years ago, so that our corner of it shows no sign of their presence? What if a probe had passed near or even through our solar system a mere 1000 years ago?)
 
shadron said:
OK, fine. Without plate tectonics we would not have multi-cellular life. Then, what do you suppose is the probability that a planet of our size will be sufficiently tectonically active to escape a snowball event?
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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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Roboramma said:
We know there is no Santa because there is no evidence where we would expect to find it.
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That does not make any sense. We are talking about Santa.

But If you are drawing a parallel with ETI, then we are alone for all practical purposes. Because there are less and less places we find that are life-friendly the more we learn about the Universe.
 
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