Intelegent life in the Universe, how common is it?

[DanS]

I don't know Sagan's arguments, but the general arguments for and against the paradox can be found here...

http://en.wikipedia.org/wiki/Fermi%27s_paradox

[:) Smiley]

Eh, ya'll seem to be the type interested in heavy-duty mathematics and space travel. Ya'll ought to go play som Galactic Overlord. The Game II sign up thread is here: http://apolyton.net/forums/showthrea...hreadid=117925

[Boris Godunov]

Originally posted by DanS
The max theoretical speed is something like 1/10th the speed of light.

Theoretical being the key word there.

Even at 1/100th the speed of light max speed, our galaxy would be awash in probes of all types in no time.

Unless, of course, no other sentient species has achieved the level of technology to do so. Why is it so inconceivable to believe other sentient beings are on a similar technological level as we are? Or even if one is so advanced as to send out such probes, that we are advanced enough to notice them?

[reds4ever]

Two guys are walking along the street:

First guy: "Theres diamond ring on the floor!"

Other guy: without looking says "No theres not"

First guy: "How do you know?"

Other guy: "Because if there was somebody would have already found it!"

[Boris Godunov]

Btw, at 1/100th the speed of light it's going to take a probe of ours 400 years to get from our star to the nearest star system, Alpha Centauri. That's a long time, and the odds are that other sentient life is nowhere near that distance to us (considering the the galaxy is about 100,000 light years across).

Even at 1/10th the speed of light, the time involved is signficant. If we were to be generous and say that another sentient species existed 100 light years from us (which is highly unlikely, even in a reasonably well-populated galaxy), it would take their probe 1,000 years to get to us, IF it happened to be on the right trajectory towards our star. That's a limited opportunity for that probe to find us, and that's not even considering our ability to detect said probe.

[smacksim]

Originally posted by reds4ever
Indeed guesswork is the best we can do at the moment, but to call it an 'equation' implies otherwise, don't you think?

'Drakes guess',while a more accurate description, does n't have the same ring of authority to it though?

At least then there wouldn't be these silly arguments over whether it's right or wrong. Oh wait, this is the Off-Topic forum.

-S

[Urban Ranger]

Originally posted by reds4ever
With all due respect, Drakes equation is a crock of sh1t.

Most of the numbers you need to plug in are guesses

So is most of Cosmology.

[Urban Ranger]

Originally posted by Odin
The Drake Equation does not have enough variables. For example, Earths tilt is kept between 20 and 25 degrees because of Luna. The Erath-Moon system is the only case of a double planet in the Solar System (I don't consider Pluto a planet, it is the largest known Kuiper Belt object, technically). Without the Moon the Earth's axis will wobble around randomly between 0-90 degrees, preventing the evolution of complex life.

On what basis do you make that conclusion? You are assuming life in an extremely narrow range, but why is that the case?

[Darkstar]

Originally posted by Boshko

But right now our technology is incapable of detecting planets smaller than gas giants IIRC.

Not true, Boshko. There are actually 2 different techniques being used now to spot smaller then Jovian worlds. Trouble is, they don't work well down at the bottom of this ocean of gas we live in. That's why there are 2 different "Earth-like" planet finding missions being launched, soon. The prequel mission for those probes is already up, scanning the heavens for targets that are "interesting" enough for the better probes to scan.

[Darkstar]

Originally posted by Edan
Ehh, what about when species are so "intelligent" that they are so succesful at"overcoming drastic situations" that they eventually become extinct due to permanent and devestating ecological destruction (possibly due to overpopulation and or trying to change the enviornment to suit their genetic programming) or nuclear war? Intelligence is overrated.

Well, depends on how fast we get out bottom's into space, doesn't it? If we don't get up and become self sustaining, it won't matter how intelligent we are... even if we figure out how not to destroy ourselves. Eventually, our sun will eat our little world.

And we continue to make progress. We are about to make fossil fuels useless as an energy source. Although we will still need them for plastics, a very real plague on the environment. And with SpaceShipOne's happy launching to the edge of recognized space, and the whole program cost *less* then Russia charges people to ride in the third seat of a launch to the ISS, there is hope that we will have non-governmental avenues to reach space.

[Darkstar]

Originally posted by Boris Godunov
It would be hard for it to be more difficult than we imagine, since the experts have concluded that interstellar travel of any significance is an extremely remote possibility.

BS. There *are* no experts in interstellar travel here. We'd have to be talking to an intelligent, tool using alien species that are highly experienced in interstellar travel to get such a ruling.

What we know is that, for us, the economics are against it. But so was a direct China-Spain exchange of goods at one point on our *little* planet.

The main evidencary point that interstellar travel is costly is that we do not have intelligent alien visitors hanging about. The more intelligent tool using species kicking around, the higher the chance that the should have a few merchants or slavers or miners or whatever visiting us.

[Darkstar]

Originally posted by Whaleboy
The thickness of the disk would be more a problem for the outer planets, since much of the gas and dust in the inner part of the disc is blown out when fusion starts in the star. That is why there is relatively little hydrogen, helium and interplanetary dust within the orbit of Mars. The gas giants must have formed beforehand, which is likely considering that such planets are failed protostars (consider that if Jupiter were 10x the mass, it would have been sufficient for a fusion reaction to occur, and the Sun would be like many/most other stars in this galaxy: a binary/trinary system). Look at the other gassy planets as evidence of that too.

Er... latest modeling and observational evidence shows you need to be in a good nursery with powerful young stars kicking back on your disk to get decent jovians. So planets, while "common" shouldn't be "normal". But we will have a much better idea in a few years, when the dedicated planet hunter probes come on-line.

[Dauphin]

Originally posted by Boris Godunov
Even at 1/10th the speed of light, the time involved is signficant. If we were to be generous and say that another sentient species existed 100 light years from us (which is highly unlikely, even in a reasonably well-populated galaxy), it would take their probe 1,000 years to get to us, IF it happened to be on the right trajectory towards our star. That's a limited opportunity for that probe to find us, and that's not even considering our ability to detect said probe.

Its not so much the amount of time thats the problem, it the right time. An intelligent species could easily have been sending out probes for the last 100 million years, which would have made it more than likely that we would have been visited by a probe. We just weren't here to see it.

[Dauphin]

And, there is nothing wrong with the Drake Equation except that its margin of error is so huge its of no practiucal use. Pin down the variables and you are getting somewhere useful.

[Whaleboy]

Got to say that those people deriding the Drake equation are taking it on face value. Sure it doesn't account for many variables, but then, it is merely a concept, used to describe a potential. We could factor in dozens, hundreds, thousands more variables and come up with one conclusion, that the universe was only suited to human life. Life is tenacious, sentience isn't merely a human trait in my view and thus we need to be careful not to create such a geocentric model as to exclude the possibility of life developing elsewhere. I suggest that the Drake equation is valid, and we need to propose different models for the variables in question, to plug a figure into the equation.