"Alien life deemed impossible"

[Spoons]

Nice work baric! And good calls too.

[Githyanki]

The Fermi Paradox is more of a question than a solution.

The scientific research over my life-time, namely, the exoplanets, is changing my view-points of other solar-systems. Once, I was certain of alien-life and many Earth-like worlds; now, I'm not so sure and leaning towards the "Rare-Earth" hypothesis.

I don't believe we can say that with a straight face anymore. The only thing the OPs article has proven is that our infant planet hunting technology has only been able to find massive gas giants or super earths for understandable reasons. Even so, I believe that at least a couple of near Earth sized planets have been discovered, some orbiting in the green zone.
Honestly, we can't run from the fact that is punching us in the face. The universe has life outside of Earth. Whether or not that life is abundant remains a question to be answered.

We can't say that for certain, other than the only life we know of is Earth-life. We can only state the possibility of life but until we found actual life outside of our solar-system or truly alien-life on Mars, then we can know for certain.

What really puzzles me is how life was on Earth so fast. That means life is really common and a natural part of planetary evolution, or life on Earth didn't not originate on it and was brought from somewhere else.

[baric]

What really puzzles me is how life was on Earth so fast. That means life is really common and a natural part of planetary evolution, or life on Earth didn't not originate on it and was brought from somewhere else.

"Really common [in the presence of liquid water]" is the most straightforward answer. It explains both the fecundity of life on Earth and its absence elsewhere in our solar system. We are just now getting to the point of being able to detect terrestrial planets in the habitable zones so I think it's premature to give up on the most straightforward answer.

[MaDeR]

The Fermi "Paradox" is ridiculous. I don't know why anyone should consider it a valid argument for anything, except for that even smart people can make daft suggestions.

Suggestion that advanced civilisation can and will make detectable signs (even with our current technology) as side effect of their usual affairs is reasonable for me. Not to mention simple fact that they are not here physically in person. These possibilites are far from certain, but I cannot dissmiss them... or rather I cannot dismiss that lack of these detectable signs/themself here can be significant.

This causes obvious conflict with Copernican Principle.

If I stand in the middle of a bushland and don't see any other people does that mean I'm the only person on the planet? Or does it just mean that I can't currently see anyone?

Even with our current technology.

[Spoons]

I imagine over many thousands of years there is a lot of technology that comes and goes. Why single out what we currently have as being the one that they'd obviously shower us in? Is ours so great or efficient?

It's just not a paradox. It's a musing that doesn't necessarily apply to much at all.

Also, if am advanced species has already determined that there are other life forms out there, would that necessarily mean that they'll be forever desperate to find more of them? Maybe the discovery that they're not alone quenched their thirst. If I want a coffee and I find a coffee shop, my desire to keep hunting for more of them wanes. I've probably htne got better things to do. Are we that amazing that they simply must find _us_ above all else? I doubt it.

[baric]

Suggestion that advanced civilisation can and will make detectable signs (even with our current technology) as side effect of their usual affairs is reasonable for me.

What kind of signs?

If you are talking about atmospheric markers on Earth-sized planets, we can't detect that yet.

If you are taking about stray EM broadcasts, we can't detect that yet.

If you are talking about transmissions specifically targeted towards us, we can technically detect that if we know where to look.

If you are talking about hypothetical futuristic sci-fi concepts like star-lifting or Dyson spheres, then I would argue that we are out of the realm of "reasonable".

[Jamotron]

Also, if am advanced species has already determined that there are other life forms out there, would that necessarily mean that they'll be forever desperate to find more of them? Maybe the discovery that they're not alone quenched their thirst. If I want a coffee and I find a coffee shop, my desire to keep hunting for more of them wanes. I've probably htne got better things to do. Are we that amazing that they simply must find _us_ above all else? I doubt it.

I disagree with this analogy. To me the situation seems more like this:
At home I have coffee and drink it regularly. I enjoy it and consider it an interesting beverage. I hear on the radio that there are places out in the city which sell coffee of many exotic varieties. After some time searching I stumble across one of these fabled coffee shops. I sample what they have to offer and add to my knowledge of coffee.
Do I now go back home never to look for new coffees again? I think I am more inclined to go and look for other exciting new coffees in the world.

[Spoons]

Maybe, maybe not. Depends on your assumptions.

Why are/were they looking?

Thing is, I don't need to prove that the certainly don't want to look any further than the few others they may have found. All I have to show is that there are reasons why they may choose not to bother scouring the universe for every slice of life they can find, and the paradox is no more.

[eburacum45]

No; you have to show that all forms of intelligent life (from sentient AI to humanoids to hive-mind slime molds and everything in-between) choose not to bother scouring the universe for life. Therein lies the paradox.

There is no reason to expect every form of intelligent life to behave in the same way; some might be expansive, others not. But it only takes one successfully expansive species to fill the Galaxy.

[Spoons]

No I don't. What? Of all of them, even if one is looking they must have sent feelers out to every location? Is this a big or small universe?

[eburacum45]

Usually it is sufficient to consider each galaxy separately. Intergalactic travel, though not impossible, is likely to be insignificant compared to interstellar travel within a galaxy.

Frank Tipler realised that self-replicating probes sent out by a single civilisation could reach every star in a galaxy within a few million years, an short period compared to the history of the Universe. Some discussion of this effect here
http://en.wikipedia.org/wiki/Self-re...ermi_s_paradox
note that a self-replicating civilisation could also fill a galaxy in a timescale which should be broadly comparable.

But here they are - not.

[MaDeR]

What kind of signs?

Anything detectable to us, but impossible to explain naturally (that is - without involving extraterrestial inteligence).

If you are talking about hypothetical futuristic sci-fi concepts like star-lifting or Dyson spheres, then I would argue that we are out of the realm of "reasonable".

Yes, I am talking about things like that. Not specifically these particular things, but anything involving similiar amount of needed energy. While they are obviously very speculative, I do consider them reasonable. For example, careful doping of star (to prolong its life) could be detectable by our current tech, at least under some scenarios.

And I will not even metion that they are not here...

[baric]

And I will not even mention that they are not here...

That form of the paradox is easier to solve, though, because it requires even more speculative technologies to exist than the first form.

[Garrison]

No; you have to show that all forms of intelligent life (from sentient AI to humanoids to hive-mind slime molds and everything in-between) choose not to bother scouring the universe for life. Therein lies the paradox.

There is no reason to expect every form of intelligent life to behave in the same way; some might be expansive, others not. But it only takes one successfully expansive species to fill the Galaxy.

But you are assuming that this alien race would find Earth attractive as a place to colonize, and of course you are assuming such a species exists at the same time as us rather than a few hundred million years before or after. For that matter a species that passed by as 'recently' as during the last ice age might just have kept on going.

[Trakar]

Yeah, basing these claim on severely biased planet list is complete failure on many levels.
1. I said this list is biased. What is means? These planets was discovered with current technology, that allows discovering only certain classes of planets. This in itself precludes discovering viable candidates - very many classess of planets are easier to discover than earth-like planets. Pulsar planets, high-mass short-orbit (hot jupiters), high-mass and/or big-sized in general, list goes on.
2. Even if this list would be unbiased statistical random sample of 500 planets with typical known amount of data (size, mass, orbit etc) from entire galaxy (we are decades away from having such list, but it should happen in my life), lack of habitable planets would mean that they are just rare. Not "impossible".
3. Mentioned above hypothetical list would be useless anyway. We do not have any information on atmosphere for most of known planets. This precludes assessing habitability at all. We can explore atmospheric models, but we do not know, how each of these are probable or possible. At most, we can pick planets that need more research (canditates to candiates for habitability).

Conclusion: this claim is unfounded and baseless.

I wouldn't go that far, but it is certainly uncompellingly supported by the evidence at hand.

[Spoons]

Usually it is sufficient to consider each galaxy separately. Intergalactic travel, though not impossible, is likely to be insignificant compared to interstellar travel within a galaxy.

Frank Tipler realised that self-replicating probes sent out by a single civilisation could reach every star in a galaxy within a few million years, an short period compared to the history of the Universe. Some discussion of this effect here
http://en.wikipedia.org/wiki/Self-re...ermi_s_paradox
note that a self-replicating civilisation could also fill a galaxy in a timescale which should be broadly comparable.

But here they are - not.

To my mind, that just indicates that the odds of life development in the way that we are predicting are lower than we might be assuming. Maybe it indicates a lack of imagination on our part, moreso than any kind of evidence that intelligent life isn't out there.

And who's to say that intelligent life necessarily focuses outward anyway? Perhaps they are content to focus much more than we are on their own planet, and doing a better job there? Not to denigrate our investigations outward, but it's not necessarily the only choice for advancement.

[eburacum45]

To my mind, that just indicates that the odds of life development in the way that we are predicting are lower than we might be assuming.

That may be the most likely answer, to be honest. Intelligent may be rare, but not vanishingly so; it may just be so rare that the closest expansive civilisation is too far away to have got here yet.

If only one in 500 civilisations is expansive, then we could easily be surrounded by hundreds of civilisations, none of which are interested in expanding. Simply creating a paradise within a single solar system is probably enough for most species.

Alternately, an interstellar species might simply move to the nearest suitable star, and stay there. Our Sun will go red giant in a few billion years; moving to a neaby red dwarf could ensure a stable environment for a trillion years.

[Garrison]

Of course it could be that if expansive species are rare there may be only one at this moment in galactic history, and we're it.

[Trakar]

Of course it could be that if expansive species are rare there may be only one at this moment in galactic history, and we're it.

Well, some members of our species have ambitions in that direction, but it is far from a demonstrated fact that we are that brand of life. I'm rooting for us!

[ryanmercer]

If you take the number of extrasolar planets found to date... then the stars that have been monitored... then do the math for the rest of just the milky way... that's easily 500k planets out there... and I suspect that number is far far higher in actuality, to tell me we are the only trace of life in the galaxy, let alone the universe... might I suggest a padded cell to those that think we are it?

[eburacum45]

There are likely to be several hundred billion planets in our galaxy. It seems very likely that life has emerged on at least some of those. But if we stay in our home solar system, we will never be able to examine that life at close quarters.

Unless, of course, that life comes to us in one way or another; there is currently no sign of that happening.

[Jamotron]

There are likely to be several hundred billion planets in our galaxy. It seems very likely that life has emerged on at least some of those. But if we stay in our home solar system, we will never be able to examine that life at close quarters.

Unless, of course, that life comes to us in one way or another; there is currently no sign of that happening.

Yeah the number is seemingly going to be much higher than 500 000, though I'm not really a big fan of predictions or extrapolations on what little data we've found so far.
I just can't wait until Kepler dishes it its first habitable zone occupying earth sized planet with a period of about one year. I'll be throwing a party on that day.

[MaDeR]

that's easily 500k planets out there...

You appear to lost one or two additional k here.

[xlaughingman]

500 planets is nothing we haven't even scratched the surface.

[neilzero]

Why not a billion advanced civilizations in our galaxy. 1000 of them are within 100 light years of Earth 10 are serious about exploring up to 100 light years from their home world. Two of them have outposts on Earth, but both perceive it is imprudent to tell most humans about their origin. Since they are more advanced than humans they can easily keep us from being sure, they are living among us = we suspect, but the hard evidence is easily debunked? Neil

[Jamotron]

Neil what are you getting at here? Are you seriously suggesting this might be the case or are you being funny?

[MaDeR]

Why not a billion advanced civilizations in our galaxy.

Too much. We would be overrun. Like in Men in Black movie, but without this ludicrous Masquerade going on.

Two of them have outposts on Earth, but both perceive it is imprudent to tell most humans about their origin. Since they are more advanced than humans they can easily keep us from being sure, they are living among us

Would be nice to have evidence for this assertion. You don't have? Surely this is just because they do so good job in hiding themself!

[Eljael]

There's an alien Howard Smith standing on a far distant planet, who may even be, at this time, looking up at the stars towards our direction and saying that they are alone in the universe. They don't believe in us either.

[Luckmeister]

There's an alien Howard Smith standing on a far distant planet, who may even be, at this time, looking up at the stars towards our direction and saying that they are alone in the universe. They don't believe in us either.

They don't have to believe. They could be like us and just continue looking as their technology improves.

....and welcome to BAUT.

[Noclevername]

Too much. We would be overrun. Like in Men in Black movie, but without this ludicrous Masquerade going on.

All depends on how advanced. If they're all at the level of Galaxy-wide interstellar travel, then sure. If they're just playing in their own back yards, we might never see evidence of them. Us? We've barely set foot outside our own doorsteps.