Friar Bellows

Yes, and it's also important to avoid adding uneccessary terms to the equation. The question is, what is necessary for the spontaneous formation of life? Does it have to be on a planet? Does it have to be carbon-based? Does permanent ice cover really rule it out? Is DNA the only way to go? Is sex necessary? And then what about intelligence? What are its preconditions? Does it necessarily lead to the development of science and technology? Is it inherently unstable? We just don't know the answers to any of these and countless other questions. We only have a few data points ... that's not much to go on in this astoundingly large universe.

Santas little helper

1. I'm not sure these are necessary conditions.Life
can exist under the surface of a planet obtaining
energy from geological processes on the planet itself.I can also imagine bacteria existing in the
atmosphere of a gas giant.

2. The Earth seems to be bombarded with material from
beta-pictoris.See here http://www.mpi-hd.mpg.de/galileo/guc...Jack/gucs_a.ps
If we receive material from there it is possible
that we have received material from a system with
a planet.
Also if part from Earth's surface was ejected
towards Jupiter it is much more likely that
it would end up on Jupiter rather than on Europa.
I'm not sure how big an impact would be required
to have material from Europa escape Jupiter's gravity and reach Earth.

3. I find it strange that Christians believe that life only exists on Earth.I'm sure there is some Biblical quote supporting this view but on the other hand if Christian religion is correct then it means that the universe was created with a purpose.It seems very unlikely that such a huge
universe was created with no other purpose than
for humans to exist.In fact to think so is very
arrogant , therefore unchristian.

4. Exactly.Some things are worth investigating just
because they are exciting in their own right.
The truth or falsity of Goldbach's conjecture is
another example which comes to mind.

Lobstrosity

The universe does have a purpose. Its purpose is to proclaim to us the glory of God...or so I've been told. I've never yet received a satisfactory answer, however, to the question of how a moon we will never know about orbiting planet we will never optically resolve orbiting a star too far away to see in a galaxy thirteen billion light years away successfully proclaims to us the glory of God. In the eyes of any rational person such an entity would be nothing more than wasted creation (assuming the entire universe was created by an intelligent entity just for us).

echidna

What's this "us", white man ?

Mageth

But again, it might be the nature of the universe that life emerges on virtually every planet where conditions are right, there may be a wide range of conditions in which life is possible (or, in this case, highly probable if not a certainty), and there may be a huge number of planets that fall within that range. Life may be all over the place.

We just don't have enough information yet to say one way or the other.

I suspect that it's somewhere in the middle. Things tend to work that way.

markfiend

Say, for the sake of argument, we do find intelligent life and do manage to communicate.

Hypothetical question, I know, but what implications would this have for religions?

I can see a number of possibilities:-[list=1][*]The aliens are atheists or are completely unfamiliar with any concept of divinity, etc. This scenario would provide support for the "argument from non-belief".[*]The aliens are theists (supported by faith) In this scenario, the similarity or otherwise of their religion(s) to any of ours would add weight to the "argument from confusion" (Interestingly, the different groups of aliens in the Galactic Milieu of Julian May's novels are claimed by her to have religions analogous to Christianity. This raises questions of God repeatedly incarnating on planet after planet to "save" each intelligent species)[*]The aliens are theists (having proof or evidence that can be clearly and unambiguously communicated) If this happens, well, game over, we atheists are wrong But I don't think this is likely![*]The aliens are deists or pantheists I don't really know what the implications of this would be.[*]The aliens have some kind of belief system that is incomprehensible to us as, I imagine, human theisms would be to them. See point 1.[/list=1]

All idle speculation, I know!

contracycle

I don't think all this pessimism about potential ET's really addresses the point. Not even the point about huiman intuition for numebrs addresses the point - that is exactly the objection the Drake Equaiton does away with.

At the moment, science considers life to be a naturally emergent property of matter, and intelligence as a property of life. Yes of course there are always boundary conditions - but the requirements for us being alone in thre universe pose more questions than they answer.

If we are the only life in the universe, then the god botherers argument is strengthened. It becomes much less hubristic to claim that we are indeed the point and purpose of the universe. OTOH, if we are not alone, are ET's saved by Jesus resurrection on earth, or did they have their own saviour, or what?

Secondly, even limiting interest to the purely secular arena, the Fermi pradox poses a very, very serious question. Because given our standing assumptions about the unflattering objectivity of the universe, it is entirely unplausible that we should be the only intelligent life, unless:

... they all wipe themselves out through nucelar war and global warming
... they all get wiped out by diseases, technology or notwithstanding
... they all get wiped out by asteroids
... they all get wiped out by some other as yet unkown pathogen

Those are all possible solutions to the Paradox. "life does not occur often or easily" is also a solution, as is "intelligence is extremely rare". Even then, we would expect, sooner or later we would come across SOME sort of evidence somewhere, sooner or later.

A simple potential solution is this: most worlds in the life zone for carbon-based life are water-worlds, and even if intelligence is possible, technology is not (so the smartest critter might be something whale-like, but will never develop fire let alone radio).

There are of course some much more worrying solutions. For example:
... they're out there, but they are hiding. Why, and from what?

This is summarised as the Hawks hypothesis. The reason we cannot see any signals is becuase there is a predator species (ala Independence Day) on the move and everyone else is either silent or dead. And yet here we are, beaming signals out across a 200 ly diameter sphere. Not a happy thought.

Now that of course really is wild-assed speculation. But the answer to the Fermi paradox is NOT a trivial one. Either our science is badly wrong, or the Paradox stands.

Now to address the possibility of communications, and whether the paradox is a paradox at all. It's possible that nobody is transmitting in the mediums that are presently accessible to us; just because we cannot see them does not mean they are not there. So its possible that our confusion is futile; however that is not much of an argument for not looking. "A different 'frequency'" is a reasonable solution to the paradox.

Are we likely to see signals across interstellar distances? Yes, obviously so - we can see the stars, can't we? Even other galaxies; long distance signals are hard but not ridiculous. Furthermore, it seems reasonable to expect, given the age of the universe, that there should be a large number of very, very old signals that have been in transit for some time. In fact, Drake worked up a 2nd equation similar to the one described above; using a limit of only 0.5 c, his computer model showed the entire galaxy should be colonised well before the earth even existed. If our starting assumptions about life are correct, then the absence of anyone else anywhere is a very serious violations of thinngs we have reason to beleive are true.

The Fermi Paradox will not go away. The sheer size of the numbers makes the (apparent) ABSENCE of life so appallingly unlikely that it requires an explanation.

Jesse

Mageth:
But again, it might be the nature of the universe that life emerges on virtually every planet where conditions are right, there may be a wide range of conditions in which life is possible (or, in this case, highly probable if not a certainty), and there may be a huge number of planets that fall within that range. Life may be all over the place.

We just don't have enough information yet to say one way or the other.

Sure, it's quite possible that life is quite common, I wasn't saying any differently. My point was just that it's bad reasoning to say there must be some others in the visible universe because 7*10^22 seems like such a gigantic number to us.

Mageth:
I suspect that it's somewhere in the middle. Things tend to work that way.

That seems pretty unlikely to me. Given all the various possible sources of improbability, how likely is it that the total probability would just happen to work out to within a few orders of magnitude of 1 in 10^22? Could just as easily be, say, 1 in 10^7 (implying about a quadrillion different intelligent life forms in the visible universe) or 1 in 10^85 (implying none at all). Given the huge range of probabilities which would all be about equally reasonable given how little we know about this at the moment, it would be pretty darn lucky if it was right in the neighborhood of a specific number like 1 in 10^22.

Marduk

The possibilities are endless (well almost endless):
There is a pattern or law governing the formation of different stars/solar systems/life and 1/X turns out like ours
Ours is a major fluke, no others
It is so rare that there are other civilizations but never more than one or two around at the same time in the whole universe.
Life evolves to the point of hunter/gatherer societies but usually goes no further
And so on and so on, no matter how smart a dolphin is he won’t be building a spaceship with those unwieldy fins.
The others, if there are any, stopped using RF long ago or haven’t started yet.
Or they may have a ‘prime directive’ do not interfere with primitive talking apes with weapons of mass destruction.
Or the UFO stories are true and they have been poking around here for years, watching, waiting for who knows what.

echoes

Humans have been around for how long? A scant two million years! And how much of the universe have we examined?

Does it make sense for us to complain about a lack of evidence to support the claim, when we have examined barely any evidence?

It's as though there are 100 suspects for a murder, and after 1 suspect is found to be innocent, the policemen grow impatient and complain that they'll never find the culprit, or that maybe it was suicide and there is no murderer. It would seem a bit premature to reach any such conclusion so soon, IMHO.

What if there were an alien civilization like this:

a)They have nearly exhausted the resources of their home planet so they begin to mine other planets in the local system for resources(The link mentioned that massive outer planets would be desirable so as to protect the inhabited planet from impacts, so the existence of other local planets seems likely).

b)Eventually their star(s) will die; perhaps they have some awesome technology that lets them obtain a sufficient amount energy from a source that is completely independent of stars.

c)They can recycle so efficiently that the finite resources of their local system could last them for a very long time.

Those 3 conditions would impose a very serious population limit, that if exceeded, would likely doom the species. Regardless, they would still be able to survive for a very long time. Is this really feasible? One obvious problem is that recycling of resources could, as far as I know, not be 100% efficient. Condition b also seems rather suspect.

Edit- I just realized that this may not be entirely clear- the point of speculating on this hypothetical alien civilization is to consider how self sufficient they could be. If they could in fact be self sufficient in their local system there would probably be little motivation to explore.