Venus and Creationism

[JS Princeton]

This I'm aware of. But as several of the articles I noted have found, the really large Jupiters and the close to the star Jupiters are creating havoc with the size of the habitable zones. Is there a published list of systems that were checked and no planets were found? I probably missed that.

The detection probability is rare enough that such a list would be truly pointless.

Yes and no. Yes, our single data point indicates that intelligent life evolved. But no this doesn't translate to a galaxy full of civilizations because we've been here for the tiniest fraction of the Earth's history.

Agreed. However, this doesn't make a "rare Earth" it only makes a "rare civilization" argument. Earth has been around much longer and life has been on Earth since very early.

So you're saying stick any planet in a habitable zone and it will be habitable? Nothing else matters? If its in the zone ( 8) ) it will automatically be able to hold onto a suitable atmosphere and liquid water?

No, I'm saying the parameter space isn't well constrained. I'm not saying it's automatic.

And as I've said, I don't think biologies are the only limiting factor.

Then you shouldn't search for habitability because habitability implies biology as being limitted to terrestrial conditions.

You need to have a planet that can hold a minimum atmosphere. A liquid boils when its vapor pressure reaches the atmospheric pressure exerted on it. So a planet has a large enough mass to be able to hold onto a thick enough atmosphere. Not a lot of biology in that if you're talking about surface ecosystems.

The assumed biology is that a) life must be on the surface and b) it requires a liquid solvent. I might give you b) but I won't give you a).

I can't say for sure what that mass is, but I'm sure eventually we'll be able to determine that.

There's actually more to it than mass. For one, we have issues with composition. Heavier atmospheres can stick on smaller bodies.

Some of the other key RE arguments are not about biology either: Is the Moon important or not? Is the mass and placement of gas giants important or not?

The key here is you underlying assumption is that you are considering only Earth-like biologies. That's the same problem with doing a search for "habitable".

[JS Princeton]

Also, that language thing. I don't think you and JS are exactly communicating the same things to eachother. Women of the world unite!!!!! You are doing a good job, you are doing a good job, you are doing a good job.........

Wishing I understood this code... :wink:

Thanks for the clarification, beskep, I agree with everything you've written.

[nebularain]

Thanks for the encouragement G-K, dgruss, and beskeptigal!

Yeah, I know about the "best explanation" thing. It's just that I've invested so much into putting together this brilliant plan I can use to completely WOW my future students about the Moon, to make them really appreciate it. I was so proud of this plan I had! Having this "reasonable doubt" pushed on me during a time when I am under a lot of stress to come up with all of these brilliant plans, among all my other projects - well, you know that expression about seeing the light at the end of the tunnel, only to discover it's an oncoming train?

Anyway, thanks again for teh encouraging words!

BTW - for clarification, now that i've gotten a bit mixed up, just what are all the conditions needed for life as we know it to currently exist on this planet?

I know the abundance of water, carbon (because we are carbon-based lifeforms), oxygen, the means for oxygen to be recycled back into the atmosphere, the recycling of water,.... What else?

[dgruss23]

nebularain wrote: BTW - for clarification, now that i've gotten a bit mixed up, just what are all the conditions needed for life as we know it to currently exist on this planet?

I know the abundance of water, carbon (because we are carbon-based lifeforms), oxygen, the means for oxygen to be recycled back into the atmosphere, the recycling of water,.... What else?

You also need recycling of nutrients - which decomposers/detritus feeders help with on our planet. You need the energy supply which can come from solar, geothermal, or chemical energy sources.

You also really need the nitrogen in the atmosphere as the Earth is today. Its an integral part of the nitrogen cycle since nitrogen fixing bacteria and even lightning strikes help convert atmospheric nitrogen into a form usable for life.

I think in broad terms you have most of the basics. You could get into the biotic structure of ecosystems. Organisms are so tightly knit in their roles that if you could eliminate all species of any particular role (all producers, consumers, decomposers) you'd have some serious problems.

[dgruss23]

dgruss23 wrote:

This I'm aware of. But as several of the articles I noted have found, the really large Jupiters and the close to the star Jupiters are creating havoc with the size of the habitable zones. Is there a published list of systems that were checked and no planets were found? I probably missed that.

The detection probability is rare enough that such a list would be truly pointless.

Really? Wouldn't those be prime stars for seeking terrestrial planets that wouldn't be overly harrassed by giant planets when the detection capabilities reach that point? One of the problems the articles I pointed to note is that these massive planets are shrinking habitable zones.

I'm also baffled that you don't think failure to detect something is important data. Shouldn't we know which planets do not have massive Jupiters within the distances that are detectable? I think some people might like to know what fraction of planets searched have these massive Jupiters.

dgruss wrote: Yes and no. Yes, our single data point indicates that intelligent life evolved. But no this doesn't translate to a galaxy full of civilizations because we've been here for the tiniest fraction of the Earth's history.

[quote JS wrote: Agreed. However, this doesn't make a "rare Earth" it only makes a "rare civilization" argument. Earth has been around much longer and life has been on Earth since very early. [/quote]

And for the first ~ 3.5 -4.0 billion years of the Earth's history there was no multicellular life. Doesn't change what you said, but its a piece of the puzzle depending on how fine you are looking to define the question.

dgruss wrote:
And as I've said, I don't think biologies are the only limiting factor.

JS wrote: Then you shouldn't search for habitability because habitability implies biology as being limitted to terrestrial conditions.

There have to be some geological factors that allow a planet to maintain the raw materials needed for life. That is habitability. I think we need to agree that we're going to disagree on this point.

dgruss wrote:
You need to have a planet that can hold a minimum atmosphere. A liquid boils when its vapor pressure reaches the atmospheric pressure exerted on it. So a planet has a large enough mass to be able to hold onto a thick enough atmosphere. Not a lot of biology in that if you're talking about surface ecosystems.

JS wrote: The assumed biology is that a) life must be on the surface and b) it requires a liquid solvent. I might give you b) but I won't give you a).

I'm glad we "might" agree on b. a is important if we're talking about intelligent life capable of communicating with other civilizations - unless you can figure out how metal/mineral materials can be drawn from rocks in a strictly ocean environment by a species adapted for water existence.
Its not strictly a biology problem.

dgruss wrote:
I can't say for sure what that mass is, but I'm sure eventually we'll be able to determine that.

There's actually more to it than mass. For one, we have issues with composition. Heavier atmospheres can stick on smaller bodies.

Of course there is more, but what molecules are out there that can be a foundation for life chemistry and heavier than the most likely candidates we have today. Ammonia is the chief alternative to our Earth chemistry that I've heard of. How about Methane? Any others?

dgruss wrote:

Some of the other key RE arguments are not about biology either: Is the Moon important or not? Is the mass and placement of gas giants important or not?

JS wrote: The key here is you underlying assumption is that you are considering only Earth-like biologies. That's the same problem with doing a search for "habitable".

Round and Round the mullberry bush ... (not that I think either one of us is a monkey or a weasle, but others may be getting a different view at this point )

[JS Princeton]

I know the abundance of water, carbon (because we are carbon-based lifeforms), oxygen, the means for oxygen to be recycled back into the atmosphere, the recycling of water,.... What else?

The atmosphere is exteremly important. It filters out most harmful radiation.

[JS Princeton]

Really? Wouldn't those be prime stars for seeking terrestrial planets that wouldn't be overly harrassed by giant planets when the detection capabilities reach that point? One of the problems the articles I pointed to note is that these massive planets are shrinking habitable zones.

I'm sorry, but this is just a bit absurd. We've found 100 some odd stars with planets about them and the rest we haven't, so the list is pretty big already. There's really no "prime target" necessary since there are so many stars out there.

I'm also baffled that you don't think failure to detect something is important data. Shouldn't we know which planets do not have massive Jupiters within the distances that are detectable? I think some people might like to know what fraction of planets searched have these massive Jupiters.

In all honesty, there are lists of candidate objects out there, but the point is that detection probabilities are so slim that people will (and should) keep checking even if someone else didn't find something.

There have to be some geological factors that allow a planet to maintain the raw materials needed for life. That is habitability. I think we need to agree that we're going to disagree on this point.

Who told you that you knew what the raw materials needed for life were? We know what the raw materials needed for terrestrial life are... but... well, now we're going down the old path again.

I'm glad we "might" agree on b. a is important if we're talking about intelligent life capable of communicating with other civilizations - unless you can figure out how metal/mineral materials can be drawn from rocks in a strictly ocean environment by a species adapted for water existence.
Its not strictly a biology problem.

Nah, it's a technological one. In fact, it can be done with much greater ease in an ocean environment (the nature of solvents, you see).

Of course there is more, but what molecules are out there that can be a foundation for life chemistry and heavier than the most likely candidates we have today. Ammonia is the chief alternative to our Earth chemistry that I've heard of. How about Methane? Any others?

Hydrogen flouride, acetone (well, there are actually many organic solvents I can think of), HCN, NO_2.... those are just a few I've seen that were looked at.

[dgruss23]

I'm sorry, but this is just a bit absurd. We've found 100 some odd stars with planets about them and the rest we haven't, so the list is pretty big already. There's really no "prime target" necessary since there are so many stars out there.

But you've got hundreds of stars that have been searched with no success. So why not start with those when searching for the smaller planets? You already have data on those systems - and you already know they don't have the Jupiters.

dgruss wrote:

I'm glad we "might" agree on b. a is important if we're talking about intelligent life capable of communicating with other civilizations - unless you can figure out how metal/mineral materials can be drawn from rocks in a strictly ocean environment by a species adapted for water existence.
Its not strictly a biology problem.

JS wrote: Nah, it's a technological one. In fact, it can be done with much greater ease in an ocean environment (the nature of solvents, you see).

Of course its technological! That's why its not strictly biological. How do you originate the kind of technology that would be needed in an oceanic environment? Sure materials are dissolved (slowly). How do you precipitate them out of the water and mold them into the kinds of materials and power sources needed to transmit signals into space?

JS wrote: Hydrogen flouride, acetone (well, there are actually many organic solvents I can think of), HCN, NO_2.... those are just a few I've seen that were looked at.

Then the trick is getting significant amounts of these substances into bodies of liquid on/in planets or moons.

[DStahl]

Interesting to speculate on technology on an ocean world. We know, from looking at biological activity in the oceans and lakes of our own planet that complex calcium mineral structures can be built underwater, that iron compounds can be manipulated, and that structures using silica and silicates can be built underwater. We also know, from our own technology, that we can create the conditions for various processes: vacuum processes, inert-gas welding, etc. So an aquatic technological culture could also create the conditions they need for a particular process.

So perhaps an oceanic technology would start by using calcium minerals and silicates just as we used wood and stone, and at later stages create more advanced processes involving atmospheric chambers, vacuum chambers, and so forth. It could be that there would be wonderful avenues of development of which we wot not, due to our puny, atmospheric environment, and that an oceanic technology would naturally find ways to do things that we haven't considered. Maybe?

But it's just speculation, of course.

[snowcelt]

However DStahl, too what we can see, technological realities of a water-bond sentient are at least a magnitude more problematic. A shot-in-the-dark, **, hypothisis? Maybe, but building a tool under the conditions of a heat dissipating environment such as water, or any other liquid environment, would at best be 'difficult.' Bio-engineering? Why not? But again, as to what has been observed on Terra: the land beasts would outstripe the sea-beasts. A water world? What are the chances? If a water world, it would be a place where the accessability to raw materials would be difficult because of pressures, depth (how long can you hold your breath?), and a work shop (where do you put the forge? If the world was some how blessed with shallow seas, what would the chances be that no dry land would not be? If so, see above. A billion other arguments can be made as to if intellegence can be, or can not be. However, we can never assume a single thing.

[Jim]

But again, as to what has been observed on Terra: the land beasts would outstripe the sea-beasts. A water world? What are the chances? If a water world, it would be a place where the accessability to raw materials would be difficult because of pressures, depth (how long can you hold your breath?), and a work shop (where do you put the forge? If the world was some how blessed with shallow seas, what would the chances be that no dry land would not be?

Oh, you air-breathing chauvinist!

Why must intelligent life on a water world be air-breathing? (Not that it's much of a hindrance; whales can dive to 1,000 meters and stay submerged for 45-50 minutes.) One of the most intelligent creatures in the sea today is the octopus. Tests have been conducted with food in a glass jar with a screw-on lid; the octopus unscrewed the lid and ate the food.

The octopus has gills. It can survive at great depths. It has eyes that are about as acute as man's. And it has arms and "hands" with which to manipulate things.

Forges? How about the vents? What if the seas were shallow enough to make them easily accessible? It should be possible to pipe hot water away from a vent and into a "forge" where it can be controlled.

Bioengineering? Sea life is already doing it. Just "train" the coral, and you can build a workshop or habitat. Sponges can be used to filter the water.

And why should there be any competition from land animals? In past extinction events, the land animals typically fared the worse. On another world, with just slightly different conditions, they might not develop much, or at all.

Ah, the possibilities!

[beskeptical]

However DStahl, too what we can see, technological realities of a water-bond sentient are at least a magnitude more problematic.
........Terra: the land beasts would outstripe the sea-beasts. A water world? What are the chances? If a water world, it would be a place where the accessability to raw materials would be difficult because of pressures, depth (how long can you hold your breath?), and a work shop (where do you put the forge? If the world was some how blessed with shallow seas, what would the chances be that no dry land would not be? If so, see above. A billion other arguments can be made as to if intellegence can be, or can not be. However, we can never assume a single thing.

If whales and dolphins had arms??? If octopi evolved a few million more years????

I don't think we want to assume what the limits of intelligent or technological life are until we learn more about other planetary environments. It may very well turn out tierra firma does better than aqua suave :wink: but I personally choose to withhold judgement until we have a bigger data base.

[snowcelt]

"If whales and dolphins had arms??? If octopi evolved a few million more years????" beskeptical: I believe I know what your judgement is vs that what is empirical (skepticism), and that which is imagination. I imagine a kind of RE universe. I think that specualation is good, as long as one does not forget what is real. As far as water borne sentients, I believe that they would not get the chance. However, I would liked to be proved wrong.

[DStahl]

snowcelt, I agree that technology underwater would be different. I don't think it would be either impossible or even an order of magnitude more difficult than atmospheric technology. Let's consider an oceanic world modelled on Europa, assuming a liquid ocean with no dry land and no access to the atmosphere; and perhaps vulcanism due to tidal smooshing and flexing of the core.

Our own oceans have manganese nodules, methane hydrates, approchable volcanic vents where chemistry was happening at a great rate, and other neat stuff that was unavailable to us as we constructed our dry-land technology. I speculate that an underwater technology would use chemistry of solutions and membranes where we might use electromagnetic devices, precipitated minerals where we might use forged metals, and pressure and temperature differentials where we use wind and hydro power. But really, I expect that such a technology would take paths I can't imagine. Since I'm pretty sure I can't imagine all the possibilities, I am very reluctant to say that it's impossible or even unlikely that a technology could arise on a world like Europa.

Still speculation...

[russ_watters]

Never underestimate the importance of opposable thumbs.

[dgruss23]

Never underestimate the importance of opposable thumbs.

They've done a lot more for technology than dolphin flippers.

[kilopi]

But you've got hundreds of stars that have been searched with no success. So why not start with those when searching for the smaller planets? You already have data on those systems - and you already know they don't have the Jupiters.

Hasn't it already been mentioned that those searches would have found close-in Jupiters, but those systems might still harbor far-out Jupiters, like ours?

JS Princeton[/url]]

I don't think you are thinking of this the same way as I am. The theory as I've understood it is that the Moon prevents the gravitational perturbations of other objects in the solar system from tugging the Earth's rotation axis around. Instead of the ~3 deg axial wobble the models suggest it could vary by up to 90 degrees.

Then why don't other planets show this? (Maybe they do, but I honestly have never heard of a 90 degree chandra wobble on Mars, for example)

I found this when I went back through the thread. I think this might be a good point, but is that supposed to be Chandler wobble, instead of Chandra wobble? You now have six points.

The Chandler wobble is the free eulerian wobble of the Earth. It's basically the result of a disturbance, and it damps out over a geologically short (hundred years) period of time unless it is pumped. Recently, a researcher claims to have identified the source of the excitation of the wobble in the movements of the oceans.

The Mars wobble that would result in pole flip would occur on much longer scale and would probably not be detectable anyway.

[David Hall]

Never underestimate the importance of opposable thumbs.

They've done a lot more for technology than dolphin flippers.

So, I guess it's time to worry then?
http://www.theonion.com/onion3630/do...ve_thumbs.html

[beskeptical]

"If whales and dolphins had arms??? If octopi evolved a few million more years????" beskeptical: I believe I know what your judgement is vs that what is empirical (skepticism), and that which is imagination. I imagine a kind of RE universe. I think that specualation is good, as long as one does not forget what is real. As far as water borne sentients, I believe that they would not get the chance. However, I would liked to be proved wrong.

Actually, it isn't speculation. Current genetic research has revealed that mammals and insects are genetically organized in the same systematic way. It only takes a few genetic differences to get from a fin to a hand to a wing.

We are so similar that in one experiment an eye gene was taken from a rabbit and exchanged for an eye gene in a fruit fly and the fruit fly grew fruit fly eyes. Mammal ancestors of whales had 4 limbs and were terrestrial. Fins have finger bones. Dolphin, whale and octopi brains are highly organized, large, and capable of complex problem solving.

Humans are clearly the most intelligent animals on Earth, but we are baby steps away from the next most intelligent animals, not leaps and bounds away.

[JS Princeton]

But you've got hundreds of stars that have been searched with no success. So why not start with those when searching for the smaller planets? You already have data on those systems - and you already know they don't have the Jupiters.

Hundreds? Try something closer to hundreds of thousands.

Of course its technological! That's why its not strictly biological. How do you originate the kind of technology that would be needed in an oceanic environment? Sure materials are dissolved (slowly). How do you precipitate them out of the water and mold them into the kinds of materials and power sources needed to transmit signals into space?

Just because you're in water doesn't mean you have to exist totally in a water environment. Sheesh, give the intelligent sea monsters some credit please.

Then the trick is getting significant amounts of these substances into bodies of liquid on/in planets or moons.

Yep.

[JS Princeton]

I found this when I went back through the thread. I think this might be a good point, but is that supposed to be Chandler wobble, instead of Chandra wobble? You now have six points.

EGG on my face! ops: Been dealing with X-rays a bit too much recently.

The Mars wobble that would result in pole flip would occur on much longer scale and would probably not be detectable anyway.

Exactly.

[dgruss23]

dgruss23 wrote:
But you've got hundreds of stars that have been searched with no success. So why not start with those when searching for the smaller planets? You already have data on those systems - and you already know they don't have the Jupiters.

JS wrote: Hundreds? Try something closer to hundreds of thousands.

Could you point me to where that is indicated because I searched and did not find any indications that they have searched that many stars for planets? What I found indicated that hundreds of stars had been searched. Thanks.

[dgruss23]

dgruss wrote:
But you've got hundreds of stars that have been searched with no success. So why not start with those when searching for the smaller planets? You already have data on those systems - and you already know they don't have the Jupiters.

Kilopi wrote: Hasn't it already been mentioned that those searches would have found close-in Jupiters, but those systems might still harbor far-out Jupiters, like ours?

Right, they might have the far out Jupiters, but they don't have the close Jupiters (Thanks - should've been clear about that distinction) so they should be good systems to search for smaller planets that aren't so harassed by the influence of the Jupiters.

[russ_watters]

Never underestimate the importance of opposable thumbs.

They've done a lot more for technology than dolphin flippers.

So, I guess it's time to worry then?
http://www.theonion.com/onion3630/do...ve_thumbs.html

Yep. We're screwed now.

Hundreds? Try something closer to hundreds of thousands.

I thought with current methods it took years of observations to get enough data to do the calculations. Plus distance is a big issue - we can only get useable info from relatively close stars - so I don't think we've looked at that many stars. Not sure though.