04-07-2004 07:47									#61
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If sentience is anything but singular, where are they all?

	04-07-2004 07:53									#62
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quote: Originally posted by DanS If sentience is anything but singular, where are they all?

Far enough away that we can't detect them.

	04-07-2004 07:54									#63
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quote: Originally posted by DanS If sentience is anything but singular, where are they all?

Observing us until we prove ourselves worthy of a seat on the Galactic Council!

Or rather, more boringly, intersellar travel maybe much more difficult than we imagine, everyones just poking around their own little bit of space wondering where everyone else is!

	04-07-2004 07:55									#64
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quote: Originally posted by reds4ever Or rather, more boringly, intersellar travel maybe much more difficult than we imagine

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.

	04-07-2004 07:58									#65
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Within the next couple of thousand years it seems likely that we will send self-replicating non-manned interstellar probes to our closest neighbors.

Why wouldn't the aliens do the same? If sentience is anything other than singular, this universe should be crawling with everybody's interstellar probes despite the distances.

	04-07-2004 08:02									#66
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quote: Originally posted by DanS Within the next couple of thousand years it seems likely that we will send self-replicating non-manned interstellar probes to our closest neighbors.

Which will still take thousands of years to travel even a fraction of the galaxy and send back data.

quote: Why wouldn't the aliens do the same? If sentience is anything other than singular, this universe should be crawling with everybody's interstellar probes despite the distances.

The distances are a lot vaster than you are assuming. Consider that that fastest man-made object ever was the Helios probe, that got up to 150,000 mph in orbit around the sun. Now, at that speed, it would take 11,000 years to reach the next closest star to earth.

If you have a galaxy teeming with life where you have sentience on 1 out of every 100 stars (which is highly unlikely), that will still make interstellar contact a remote possibility.

Besides, the other sentient species could, hypothetically, not be as advanced as us, or just as advanced.

	04-07-2004 08:03									#67
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quote: 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.

I would suggest that the degree to which the axis of rotation effects the planet is dependent upon where in the habitable zone the planet is, the albedo of the planet (one would expect it to have a higher effect with a lower albedo) and also of course the presense of other planets at all. Consider that were it not for the moon, the other gravitational influences would be mostly Venus, Mars and Jupiter (to a lesser extent) and Saturn to a far lesser extent. Remove all planets but Jupiter and you have a more stable system in operation, though admittedly not by much it would potentially allow evolution to adapt. This of course relies on a Jupiter-sized object at that distance, and we have seen larger and smaller exoplanets at a variety of ranges to their parent star.

quote: Onother trump card is the thickness of the stellar disc. If the desc is too thick and dense it will cause the planets to spiral inward untill the disc is cleared. this is carried to great extremes with the systems with "epistellar giants", gas giant planets that are closer to their star then Mercury is to the Sun. The only hope for such systems is if a Jovian planet with an earth-sized moon ends up in the star's habitable zone. There is one such planet known. HD177830 b is a 1.28 Jupiter mass planet orbiting the K0 (yellow-orange) star HD177830, located 192 light-years away in the constellation Vulpecula. This planet is likely to be within its habitable zone. A moon found here could have liquid water and look similar to Earth.

Would expect that planet to be very heavily irradiated, which is a problem, though not a fatal one as far as life is concerned. 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.

	04-07-2004 08:05									#68
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quote: Originally posted by DanS Within the next couple of thousand years it seems likely that we will send self-replicating non-manned interstellar probes to our closest neighbors. Why wouldn't the aliens do the same? If sentience is anything other than singular, this universe should be crawling with everybody's interstellar probes despite the distances.

You should at least reference the above, instead of passing it off as your own

It's called Fermi's paradox and, it too, like Drakes equation is a crock of sh1te.

try putting 'Fermi's paradox debunked Sagan' in to Google and have a look round.

	04-07-2004 08:08									#69
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quote: 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.

I agree Boris, but it does n't stop 'the man in the street' (or people here for that matter) asking the question, 'if they are out there why havn't they found us?'

	04-07-2004 08:12									#70
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quote: Originally posted by reds4ever I agree Boris, but it does n't stop 'the man in the street' (or people here for that matter) asking the question, 'if they are out there why havn't they found us?'

Ignorance on the part of the man in the street is no excuse. The answer is simple: The distances between us are too vast.

	04-07-2004 08:15									#71
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quote: Originally posted by Boris Godunov Ignorance on the part of the man in the street is no excuse. The answer is simple: The distances between us are too vast.

OK, OK I give in, I worded it wrong. Happy now???

	04-07-2004 08:17									#72
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quote: The distances are a lot vaster than you are assuming.

The max theoretical speed is something like 1/10th the speed of light. Even at 1/100th the speed of light max speed, our galaxy would be awash in probes of all types in no time.

	04-07-2004 08:21									#73
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quote: Originally posted by DanS The max theoretical speed is something like 1/10th the speed of light. Even at 1/100th the speed of light max speed, our galaxy would be awash in probes of all types in no time.

MESSAGE REPEATS:

It's called Fermi's paradox and, it too, like Drakes equation is a crock of sh1te.

try putting 'Fermi's paradox debunked Sagan' in to Google and have a look round.

	04-07-2004 08:24									#74
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quote: It's called Fermi's paradox and, it too, like Drakes equation is a crock of sh1te.

Much less a crock of **** than Drake's equation (which is a total crock of ****). It's brings up a lot of interesting questions about our place in the universe.

For the record, I chose "Unsure". Personally, I think looking for aliens is a pretty poor allocation of scarce resources, but there you are.

Edit: With regard to Sagan, he was more of a politician than a scientist. I might do the Google search as you suggest when I get a chance though.

	04-07-2004 08:27									#75
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quote: Originally posted by DanS Much less a crock of **** than Drake's equation (which is a total crock of ****). It's brings up a lot of interesting questions about our place in the universe.

Then you know the arguement against it?

	04-07-2004 08:36									#76
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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

	04-07-2004 09:26									#77
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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/showthre...threadid=117925

	04-07-2004 09:27									#78
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quote: Originally posted by DanS The max theoretical speed is something like 1/10th the speed of light.

Theoretical being the key word there.

quote: 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?

	04-07-2004 09:50									#79
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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!"

	04-07-2004 09:55									#80
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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.

Last edited by Boris Godunov on 04-07-2004 at 10:08

	04-07-2004 10:49									#81
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quote: 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

	04-07-2004 12:03									#82
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quote: 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.

	04-07-2004 12:05									#83
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quote: 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?

	04-07-2004 13:39									#84
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quote: 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.

	04-07-2004 13:44									#85
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quote: 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.

	04-07-2004 13:54									#86
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quote: 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.

	04-07-2004 13:59									#87
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quote: 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.

	04-07-2004 15:48									#88
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quote: 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.

	04-07-2004 15:51									#89
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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.

	04-07-2004 16:14									#90
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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.