Well, I think we may be referring to different meteorites, the well published one had what appeared to be fossilised bacteria, though gas bubbles could theoretically end up looking that way. The meteorite I was referring to had no biological apparatus, but did have these magnetite crystals, which by their uniform size and morphology suggested they were linked to the magnetotactic bacteria I referred to.
As for not being able to recognise non-dna life, I'd disagree, there are several known chemistries that could do the same job with carbon, and even a handful that could do it around a nitrogen, silicon or sulphur base. The question is not whether it would be recognised as life, but more whether it would be accepted as life by the general population.
Originally posted by EinsteinMindI'm afraid not, the big bang started the universe and all of the matter within it, but life started by chemical processes. It is possible, as previously mentioned that some other cause could have seeded life on both planets relatively simultaneously, but they would have followed very different evolutionary paths and probably would've been nothing alike. Humans certainly have never been there, since Mars has been uninhabitable for much much longer than humans have been around.
I am wondering what would hhappen if the Big Bang deposited life on both planets, then humans began slowly evolving on both planets, but one grew less and less habitable while one stayed perfectly habitable.
Is this a possibility?
Originally posted by agrysonAre the scientists even agree to a definition of life? That not only include various Earthly lives, but also non-Eartly ones? A living DNA kind of life form is easy to detect, even dead ones if DNA is extractable, but non-DNA i don't think we can, unless its morphology is like ours.
Well, I think we may be referring to different meteorites, the well published one had what appeared to be fossilised bacteria, though gas bubbles could theoretically end up looking that way. The meteorite I was referring to had no biological apparatus, but did have these magnetite crystals, which by their uniform size and morphology suggested they were linke ...[text shortened]... be recognised as life, but more whether it would be accepted as life by the general population.
If someone knows the unambiguous and universal definition of life, please, tell us.
there is none, that's why it'll be so hard to define when artificial intelligence becomes 'alive'. But there are general trends, which are that it is self replicating or capable of such, that it gets its energy from its environment and that after progressive generations it evolves. Even those are contested, but just because it doesn't have its picture in a dictionary doesn't mean that it's not life. certain geological formations follow the above trends, are they life? Dunno, but the point is that we know the chemistries involved and that if we found something entirely different from us, but that was potentially life, it'd at least have a fighting chance of being recognised.
Originally posted by agrysonThere is an article in the latest Scientific American about the beginnings of life using very simple compounds, take a read. Its on the newsstands now.
there is none, that's why it'll be so hard to define when artificial intelligence becomes 'alive'. But there are general trends, which are that it is self replicating or capable of such, that it gets its energy from its environment and that after progressive generations it evolves. Even those are contested, but just because it doesn't have its picture in a ...[text shortened]... but that was potentially life, it'd at least have a fighting chance of being recognised.
Time will tell about life on mars for sure. My bet is on it being regular DNA because we are too close galactically speaking to not have shared at least life starting chemicals if not life itself in the form of bacteria in meteorites from earth to mars or vice versa.
There are life, even on Earth, which has no DNA of the kind that we have. Mitocondria, that we can find inside every ordinary animal cells, and are independently reproducing themselves.
Inside plant cells we can find chloroplasts, but these I don't know nothing about. Do they have ordinary DNA?
Originally posted by FabianFnasMitochondria do have dna, as do chloroplasts see the links below. It's true that they probably started off as separate cells and then formed a symbiotic relationship with more complex organisms, but they definitely have commoner garden DNA. I don't personally know of any terrestrial life that does not possess DNA, or is produced by DNA.
There are life, even on Earth, which has no DNA of the kind that we have. Mitocondria, that we can find inside every ordinary animal cells, and are independently reproducing themselves.
Inside plant cells we can find chloroplasts, but these I don't know nothing about. Do they have ordinary DNA?
Any examples that you know of?
http://en.wikipedia.org/wiki/Mitochondria
http://en.wikipedia.org/wiki/Chloroplast
Originally posted by agrysonYes, they have DNA but not with the four aminoacids TCGA (I wrote "DNA of the kind that we have", didn't I?). If I don't misrecall mitochondria DNA consists of UCGA as its aminoacids.
Mitochondria do have dna, as do chloroplasts see the links below. It's true that they probably started off as separate cells and then formed a symbiotic relationship with more complex organisms, but they definitely have commoner garden DNA. I don't personally know of any terrestrial life that does not possess DNA, or is produced by DNA.
Any examples that yo ...[text shortened]... now of?
http://en.wikipedia.org/wiki/Mitochondria
http://en.wikipedia.org/wiki/Chloroplast
What chloroplasts has as aminoacids in the 'ladder steps' in their DNA, I have no knowledge about.
Yeah, but it's still based on the same precursor chemicals (the four bases in human dna can lead to twenty different amino acids, whatever the nucleotide base pairs used are, the resulting dna still performs the same function in the same way using the same transcription mechanisms) While it is true that these cellular machines can have different base pairs, and do not all use a double helix conformation, they still contain DNA with base pairs and nucleotides that transcribe to form RNA and eventually amino acids and proteins. The precise chemical involved does not affect the chemistry involved. It's still DNA and it's still the same mechanisms involved.
Originally posted by agrysonPretty small potatos the diff between the two, when you look at the twisted pair chain they are almost identical there. What we might see as we get into interstellar space is life based on something other than carbon, like silicon, it can form chains maybe not as complex as carbon but can still have incredible complexity on its own, maybe enough for life where carbon was not given a chance, say on a planet with plenty of water, nitrogen, hydrogen and so forth but little carbon, maybe silicon could have a chance given billions of years of no carbon competition. I would think maybe other physical structures would form, maybe a tri-axial twisted pair or a quad chain or a single long strand, who knows. I think the human race is going to be in for some big suprises in new life forms when we finally go interstellar.
Yeah, but it's still based on the same precursor chemicals (the four bases in human dna can lead to twenty different amino acids, whatever the nucleotide base pairs used are, the resulting dna still performs the same function in the same way using the same transcription mechanisms) While it is true that these cellular machines can have different base pairs, ...[text shortened]... ot affect the chemistry involved. It's still DNA and it's still the same mechanisms involved.
Originally posted by sonhouseI think Universe is still to young to have time neccesary to evolve life based on silicon. Carbon is ideal.
Pretty small potatos the diff between the two, when you look at the twisted pair chain they are almost identical there. What we might see as we get into interstellar space is life based on something other than carbon, like silicon, it can form chains maybe not as complex as carbon but can still have incredible complexity on its own, maybe enough for life wh ...[text shortened]... race is going to be in for some big suprises in new life forms when we finally go interstellar.
But nevertheless, carbon is a very abundant element in universe.
Originally posted by agrysonSilicon is not likely to begin life with. It takes time to create complicated molecules. And how about solubility in water, or is some other solvent neccesary suitable to life in some kind?
True, carbon is common, and it's simple to get started, but silicon is much more abundant. Dunno, suppose we'll just have to wait and see...
It is easy to imagine all kind of lif forms. But I think there is principles that make life easier to evolve into organisms. The presense of carbon, the presense of water, the presens of 'right' temperature and other.
My opinion is that if you have a planet of the right properties, there is only a matter of time berfore life evolves. It happened on Earth. It could happen in any planet similar to Earth. If only the properties are right.
(I like this thread a lot!)
Originally posted by FabianFnasDid you hear about the anomolies on top of the Venesiun atmoshere?
Silicon is not likely to begin life with. It takes time to create complicated molecules. And how about solubility in water, or is some other solvent neccesary suitable to life in some kind?
It is easy to imagine all kind of lif forms. But I think there is principles that make life easier to evolve into organisms. The presense of carbon, the presense of ...[text shortened]... any planet similar to Earth. If only the properties are right.
(I like this thread a lot!)
Some folk are saying there is some UV signs of life there, high in the atmoshere where conditions are not as hellish as on the surface. I wonder when a probe will call on the upper atmosphere to take a sample and prove or disprove this theory. The question then would be how could such life form (1 come about and (2 not sink to the hell that is Venus proper. I would think it could come about if the Hoyle theory is true, life coming from giant molecular clouds in interstellar space or even meteorites from earth or mars breaking up in the atmosphere and forming some kind of floating bacterial structures.
It maybe could have evolved membranes filled with H2 which would keep it afloat forever. Food for thought, eh.