Well there are multiple theories:
1) Gliese 581d is an ocean planet with a thick hydrogen helium atmosphere... The ocean itself is mildly acidic and contains various minerals and salts...
2) Gliese 581 d has land mass but gravity is to high to walk on as a human will have a heart attack on the surface...
3) Gliese 581 d is an ice covered cannonball with a medium sized atmosphere... It has no magnetic field...
4) Gliese 581 d is an ice covered water world with a small atmosphere comparable to mars...
In all cases it is tidaly locked or has rotational resonance similar to mercury...
Based on what data?
How did you come to those conclusions? If you don't mention any work or thought leading up to it, it gives the appearance that it's entirely made up. Mention how you arrived at each case;
Show your work. It's very important.
1) Gliese 581d is an ocean planet with a thick hydrogen helium atmosphere... The ocean itself is mildly acidic and contains various minerals and salts...
On a planet with liquid water, or any planet warm enough, in that temperature range, you won't find raw hydrogen. Hydrogen has a tendency to bond with things, so it would all be locked up in different compounds, such as water, minerals, or the atmosphere (C02, like mars has).
Mars for instance is rich in peroxides on the surface and C02 in the air for this reason, IIRC.
Not to mention hydrogen is the lightest element (remember how blimps float?), and so it sticks to the extreme upper layer of an atmosphere, which means it blows off into space first, from solar radiation. It's also very light, which makes it an even easier target to get blown away by solar radiation.
2) Gliese 581 d has land mass but gravity is to high to walk on as a human will have a heart attack on the surface...
Even a water world has land mass, albiet thousands or hundreds of thousands of feet underwater. And I didn't know high gravity caused heart attacks...
---------- Post added at 09:32 PM ---------- Previous post was at 08:51 PM ----------
Hypothetical types of biochemistry details some of the problems and possible advantages of alternate biochemistries.
"They would work" doesn't mean much; I can conjure a super axion hypergravity reactionless drive and state that "It would work", but without any proposition about
how it work work, scientific speculation is entirely meaningless.
It's not just meaningless speculation. There's been quiet a lot of work put into it, and it's not a crazy concept. From the amount of work and attention it's gained, and the fact I've never heard this sort of criticism from inside the scientific community, I get the notion that it's a respectable idea.
There's a good reason we can't list exact designs,
1) There's many variables which can have many values that results in millions of different setups. It's a chaotic system. We know how DNA works, so if other chemical compounds can replicate working DNA, nature has shown us there's thousands of ways to do other things, so doubtless, whether as energy efficient or not, there are ways to do things (such as controlling cell permeability) using different compounds as long as the meet certain requirements. Not to mention engineering the structure of alien DNA on top of all that.
2) Actually, we
can. I've already mentioned this but I get a feeling it was "TL
R"'ed. It's important: Titan's lack of hydrogen in the lower atmosphere grabbed a lot of attention because the model for Methane-based life breathed hydrogen.
The model for Methane-based life. So the models do exist, I just personally don't know them. (Though I would be interested, and perhaps over my head, to discover and read them.)
And finally, you need the exact design specs if you're going to build something like a "super axion hypergravity reactionless drive". If you're discovering something, however, and you try to draw exact design specs, you'll oft be disappointed. Nature is mostly predictable at a much lesser degree.
And, once again, you need only know it's hypothetically possible and likely to exist it's likely to be discovered.
When it comes to building something, you need exact blueprints and specs.
But we don't have exact blueprints and specs for alien life, do we? Yet we still expect to discover it, because it's hypothetically possible and likely to exist. The exact same applies for alternate biochemistires.
The understanding that my uneducated mind has about temperature is that it is based on particle movement. At a lower temperature the speed of particles in a medium is reduced, which means the speed at which reactions take place is reduced. It isn't about the amount of energy that a chemical reaction yields, but rather the time it takes for reactions and changes to occur.
And that's correct, at least the first part is. And the last part. But the energy a chemical reaction yields is vital for if it's potent enough to create life. And the rate at which changes occur is also vital, but this also varies with different reactions. Iron rusts, hydrogen reacts with oxygen, and N204 reacts with Monomethylhydrazine (MMH) at much different rates, all at the same temperature (albeit they
produce different temperatures.). Also to be taken into account is pressure and density of the medium, which also effects the rates of changes.
It might be colder, but it could happen slower, as fast, or even faster than water-based chemistry depending on the
specific chemical reactions that take place.
You could demand to know the specific chemical reactions, but listing every possible chemical reaction under a wide range of conditions is difficult enough, but then creating a variety of models to utilize them for life is impractical to the nth degree.
It would also imply that it's impossible for us to discover anything new, by stating that we won't find it because we can't figure out how it'd work.
Plants move and live slower than we do because they don't
need to live fast. Most of their competition (other plants, that could shade them, for example) also moves slowly, and they don't have to worry that much about being eaten (if your leaves are removed, it means you are damaged, not dead) and use mostly passive defences against 'predators', and they also don't have that much energy (I'm
assuming; primary consumers benefit from the producer concentrating energy, just as secondary consumers benefit from primary consumers concentratng energy) to move about with. They don't need to find food; just bask in the sun and extend their roots towards water.
It should be noted, however, that plants are not just dumb organisms that sit around and do nothing. They viciously compete, grow, and move, although of course, not on such a timescale as many animals. For example there is
Tropism,
Nastic movement, and
Rapid plant movement (as seen in carnivorous plants).
And a good deal of animals are pretty slow movers as well; there are many sessile invertebrates, and some animals can be easily mistaken for odd plants by an uneducated person (specifically corals and sponges). Often these move faster than plants, but they do have many similarities. Generally, plants are autotrophs and animals are heterotrophs. Even animals that photosynthesise only do so via symbiosis with photosynthetic algae.
Plants live on a slower timescale because they aren't able to move faster from autotrophic feeding based off of sunlight alone. Carnivorous plants have rapid movement, but they're also heterotrophs, and don't live off of photosynthesis alone.
As for sponges and slow animals, they feed at an extremely reduced rate, which means the same reactions occur at a much slower pace. I think this would be a good example of how variable life can be based off of specific reactions, which is an argument
for fast-moving non-terran biochemistires.
It is doubtful that elsewhere we will find "plants" or "animals"; we might find wholly alien kingdoms of life, similar to them, one, the other, or both. Or contain a whole lot of odd traits but not be generally identifiable as analogous to anything from Earth.
Maybe on many worlds, there are no "animals" like vertebrates, or arthropods, or cephalopods, but rather entire ecosystems of odd sessile and semi-sessile life, competing and surviving with all the amazing ferocity as life on Earth, but at a pace only detectable by time-lapse.
In that case, you would not be worried about shooting gigantic creatures, but rather worrying about waking up to find that those pesky landstars have crawled across your compound and are covering your electrolysis plant, trying to find a place to warm up and offer sunlight to their symbionts. You grumble and set out to pry them off, complaining about how darn sticky their pseudopods are...
Lol, I like the end. Maybe some folks off-world didn't hear the story right, and it's been glamorized and exagerrated by the futuristic equivalent of "Hollywood". Just think of how much most people are mis-informed on things like spaceflight, and imagine how easily most people from off-world could be mis-informed on how the landstars are, especially if they look alien and frightening.
Just imagine... Some easily frightened person from off-world has a mental image of terrible, unstoppable, invincible but painfully slow monsters, and a local says: "Ugh, they've entered the perimeter again." and walks out to pry the 16-foot wide nightmarish landstar covered with squid-like suckers off the fence with a crowbar, grunting and cursing with frustration while he does it :lol: .
Anyways, there's a good reason there's a big division here, and that's that photsynthesis doesn't create the same amount of living energy budget as consumers get. Essentially, plants make energy from sunlight, store it up over months and years, then we hetrotrophs come along and use up all that energy in just a day or less.
And finally, I think I'll highlight a specific point I like: To say we have to understand it before it's discovered would imply that it's impossible for us to discover anything new, by stating that we won't find it because we can't figure out how it'd work.
When it comes to something as diverse as life, and the entire field of chemistry and biology combined, I am more than hesitant to say we won't discover anything new, and saying we won't discover it because we can't figure out how it'd work is
exactly that.