Jayjay

Yeah, you're right. For some reason I thought that they suffocated inside the station instead of re-entry.

Happy Wonderer

There is another dimension that is ignored in the Fermi paradox: time. How many years has the earth been "visible" as the result of an advanced civilization? (I think we started transmitting radio about 80 years ago.) Compared to the length of time that a civilization could have been on earth had evolution and history been a little different? (at least one billion years, I'd say.)

For us to detect another civilization, not only do they have to happen to be in one of few (out of billions) of galaxies that we could detect them in, they also have to be in existance at the right time -- which may be many millions of years ago.

Unless you are a hopeless optimist, I don't think that our civilization is going to last more than a few thousand more years. (At the rate we are going, I'd say 500 max before some terrorist somewhere gets the bright idea to release a GM version of ebola into the population.) It could easily be the same with other civilizations that reach our level of technology (depressing thought )

It may just be that it is impossibly unlikely that the lifetime of our civilization will overlap with that of another -- or more precisely, that our 'technological time' will overlap with the timing of signals from another civilization.

Of course I consider the paradox itself not to even be close to evidence -- if we don't know the odds of life arising on a planet, how can we even begin to say what the odds are that technological life will happen to arise on some planet that happens to be close enough for us to detect it during a timeframe that we could see it? Heck, we can't even see planets in other solar systems (although we have evidence of them.)

HW

Lobstrosity

But your first sentence is one gigantic hypothetical. No naturalistic theory predicts that we would "see" anyone out there, either. Our technology is incredibly limited, so even if every star out there had at least one planet around it with life, how would we expect to know? For 99.999999% of Earth's history, no one looking at us from a distant star would have any way of detecting the presence of life. Now, suddenly, we discovered how to produce radio waves. Now we have abruptly provided a way for someone to see us. Well, how many planets out there have organisms that are listening right now? Maybe they haven't reached a level of intelligence necessary for such detection yet. Maybe they're beyond this stage and are listening for some other signal they would expect from what they would consider "intelligent" life.

Another good question is one brought up by Happy above: once intelligent life evolves, how long does it last? We have no data on this whatsoever. It doesn't strike me as strange to hypothesize that intelligent life forms will self-destruct in an incredibly short amount of time. Humans can almost be viewed as a cancer (yes, I know The Matrix has made this statement cliche, but I'll go with it anyway because it was a concept I came up with before The Matrix and I need it to illustrate a point). We're incredibly efficient at reproducing...perhaps too efficient. Just like cancer reproduces so well that it displaces vital tissue and eventually kills the host (thereby killing itself), perhaps humans will do the same, decimating earth with our intelligent manipulations until we ourselves can no longer survive. Cancer is not inherently "evil"--it just does what it does. Similarly, we aren't inherently evil, we just do what we do and that could easily lead to our downfall if our predictive intelligence does not keep up with our creative intelligence (i.e. if we fail to see the eventual dire consequences of something novel we decide to try). What if we keep using our intelligence to develop bigger and "better" weapons. We already possess enough nukes to make this planet unihabitable. Humans are not infallible and if we end up making a weapon that could kill us all, there is no guarantee that one deranged individual won't actually use it. Humans have a proven history of putting insane/moronic people in seats of power--people who would control the fates of all humanity if technology continues to provide us with more and more destructive capabilities. It may turn out that intelligence is a quick ticket to extinction, in which case the chance that our intelligence window will overlap with another world's intelligence window is extremely small. This universe is 13.7 billion years old. Humans have been been producing detectable signals for less than 100 of those years. Humans have been looking for detectable signals of intelligence for less than 100 years. Maybe those signals stopped a million years ago. Maybe they won't start for another million years. That's just a mere instant from now on the cosmic time scale, so such a thing wouldn't be at all unreasonable to presume.

At any rate, it all simply goes to show that the Fermi paradox isn't a paradox at all. We have no information at all as to whether life is anywhere else in the universe. All we know is that a few stars aren't currently broadcasting EM radiation in one particular band we happen to be listening to. This lack of evidence for intelligent life does not provide us with any ability to speculate because there are a billion possible explanations, all of which are equally plausible.

And finally, I would argue that the universe itself "evidence" against creation. Sure, current interpretation of creation would predict that Earth has the only life (or at least the only intelligent life) in the universe. (As an aside, based on the history of Christianity, I'm sure if intelligent life is eventually detected elsewhere creationists will simply revise their stance to say that not only is this permitted by the Bible but that the Bible actually predicted it all along.) The current interpretation of creation also predicts that our earth should be the entire universe. Instead, we find that there are billions upon billions of suns just like our own out there. Each of these is probably surrounded by planets. If God made the universe just for us, why in the name of God (heh) did he bother making entire galaxies of stars and planets 13 billion light-years away from earth? What purpose would that serve? It seems like a whole hell of a lot of wasted creation to me. If he bothered to make all that potential living space, why not also fill it with living things (and don't say that it's future living space for us--we know quite well from physics that nearly all of the stars we currently see in such galaxies have already died)? To me, that's a reasonable question to ask of a reasonable God. This is why I would respect creationism much more if it actually spoke of the creation of life elsewhere in the universe. As it stands now, it's just a narrow-minded, egocentric notion meant to make the believer feel all special (just like the false concept that the Earth was the literal center of the universe about which all else revolved--people actually imprisoned Galileo for daring to challenge that idea).

Kosh

I am however, waiting for that Hubble snapshot that accidentally catches a passing alien spaceship portal, containing a little green alien kid looking out with his thumbs in his ears going:

beausoleil

No offense intended, but there seems to be some misunderstanding of what Fermi's 'paradox' is. It isn't a paradox on its own. In a nutshell, it reads 'if they existed, they would be here'. Our present low capacity to search the galaxy for life has nothing to do with it.

You can form the argument this way:

We can reasonably foresee being able to start the following strategy within the next thousand years.

- Design self replicating probes capable of, say, c/100.

- Aim them at nearby stars with the instruction to explore, construct versions of themselves at their destination, and despatch these replicas to other stars further away from Earth than their current location.

Using this strategy, it takes about 10 million years for every star in the galaxy to be visited by one or more probes. The galaxy is 12 billion years old, plenty of time for another civilization's probes to have reached our solar system even if we assume that civilization can't arise until stars with metallicity similar to the sun's have begun to form.

It lends no support to creationism whatsoever. All it suggests is that the likelihood of civilisations similar to our own arising is somewhere around or below the 1 per (milky way size) galaxy per 10 billion years mark, which is well within our margin of error in calculating (you can barely call it 'calculating' anyway) this number from our limited understanding. (I say 'or below' because it might be a lot less, right down to the one per universe per 10 billion years, without our presence being considered anomalous) It does suggest some of the more optimistic discussions of the Drake equation are questionable IMHO.

Lobstrosity

I wasn't familiar with the specific Fermi paradox, so I was just responding to what Jayjay gave me to work with. Knowing the true structure of the "paradox," I'm still of the same opinion. Another factor is whether the intelligent life forms would design self-replicating probes to visit every star in the galaxy in the first place. Would the probes actually work as intended with anywhere near 100% efficiency? What would the probes actually do once they got here? Maybe a probe came, mapped the place and left/crashed into the sun millions of years ago. Maybe it's at the bottom of the ocean burried under countless meters of sediment. Maybe it's still orbiting Earth way out there completely undetected by man. It's hardly a sound argument against other intelligent life's having existed in our galaxy.

Bumble Bee Tuna

Doesn't this ignore the idea that maybe, just maybe, interstellar space travel just isn't viable? How are these probes getting here? What are the using as fuel? Engines?
I don't "reasonably foresee" is being able to make probes that acn go c/100 in the next thousand years. I could see us killing ourselves first. I could see it being a scientific impossibility. I certainly do not see these probes being able to 'construct new versions of themselves at their destination'. What if their destination does not contain viable materials for doing so? Where will they get the materials? Is the probe capable of mining the planet on its own? Why can we assume that alien cultures would want to spend so many resources on millions of space probes? Why can we assume they would have the resources to do so?

Honestly the concept of self-replicating explorer probes sounds ridiculous to me. We have no way of knowing that it's possible, therefore it's ridiculous to claim "they would be here". There is no evidence to lead us to believe it is possible.

-B

Lobstrosity

Maybe other "intelligent" life is convinced that God made the universe just for them and wasting time exploring an empty universe is a pointless excercise in futility? If the Creationists had their way we would never consider sending out such probes even if we had the technology. What would we hope to find?

_|ason

I was under the impression that the universe is expanding (not sure at what rate though). Would this not greatly reduce the chances of finding life out there (or them finding us)?

MyKell

Depends on what the method of interstellar travel is. For wormholes, I don't think it's a problem at all. For other FTL (faster than light) travel methods, it should only be a problem intergalactically, not intragalactically!