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About LinkBacksI am wondering exactly how life started in the universe and took its trip to Earth. I've heard that it came in on a Comet, or was it Already here?
I read much about the evolution of life on Earth, but still dont know the exact Origin of it.
October 30th, 2008, 02:09 PM
I am wondering exactly how life started in the universe and took its trip to Earth. I've heard that it came in on a Comet, or was it Already here?
I read much about the evolution of life on Earth, but still dont know the exact Origin of it.
Panspermia isn't that widely accepted theory of how life first got to Earth.
There are numerous theories of abiogenesis and the origin of life that you can read about on wiki
http://en.wikipedia.org/wiki/Origin_of_life
Maybe you could come back with more specific questions.
My Question is How did life Start?
amino acids and purines and pyrimidines can form naturally in suitable environments
They then polymerised and formed some some sort of membrane around them. Those that replicated best survived, and complicated until bacteria formed.
It was God, of course! Right Dayton?
The origin of life is currently not fully understood. There are several feasible ways in which it may have happened and these are summarised neatly in the Wikipedia article on "abiogenesis" (the origin of life from lifeless matter).
http://en.wikipedia.org/wiki/Abiogenesis
Right now the various hypotheses on abiogenesis are just that; hypotheses. There is no widely accepted theory on the matter, but many possibilities.
Yes thanks for that Article, Very interesting
"Gravity explains the motions of the planets, but it cannot explain who set the planets in motion. God governs all things and knows all that is or can be done." -- Sir Isaac Newton
"The heavens declare the glory of God; the skies proclaim the work of His hands." -- Psalm 19:1
Science - I was being sarcastic. God does not exist.
Since you've never left planet Earth or observed even less than .0000000001% of the universe, I take it that you're an omniscient atheist demigod who is infallible. Can I borrow your crystal ball or time machine some time?Originally Posted by verzen
No, but you can borrow my common sense. 8)
A bit of perspective, Tharghana, that often goes unmentioned (as I recall, in that linked wiki), is that life on Earth began as soon as possible. Like, where we thought the primordial Earth too hostile for life, we're finding it. This suggests that life starting up by whatever means, rather than being "astronomically improbable", is actually very probable or even inevitable, given just the worst conditions.
If you're looking for life in the galaxy, it's worth noting that our kind of solar system with terrestrial planets is a relative newcomer. The first stars lacked all the ingredients (elements) for solar systems. Those had to live and die and by that process seed rich systems like our own. So, again, Earth itself appeared as soon as possible in the galaxy's development. Well, statistically very early. We've yet to find a system of our own kind so old. But many more will follow. This is a pretty good argument against panspermia.
It is not at all scientific to assume the existence of supernatural beings on the basis that we can't look everywhere and fail to see them. I could as easily argue that the Flying Spaghetti Monster lives in the atmosphere of Neptune. You can't prove me wrong so it must be true.Since you've never left planet Earth or observed even less than .0000000001% of the universe, I take it that you're an omniscient atheist demigod who is infallible. Can I borrow your crystal ball or time machine some time?
When you think about it, the assumption that a God exists is far more likely to be a human invention in reaction to the fear of death and meaninglessness. As a "scientific" explanation it is total garbage since all it does is postpone the question of the beginning of life and matter to "what created God and why", which is invariably answered with the massively unsatisfying concept of a timeless entity without cause. It also adds a layer of complexity to our explanation of the universe- which would only be scientifically acceptable were there evidence that this was required to explain something. It's not required at all.
October 31st, 2008, 10:36 AM
How is this any different from your argument, wherein you claim you know of God's omniscient presence without ever leaving planet Earth or observing more than .0000000001% of the universe?Since you've never left planet Earth or observed even less than .0000000001% of the universe, I take it that you're an omniscient atheist demigod who is infallible.
This is even more suggestive of panspermia, until and unless we have established a wholly plausible suite of prebiotic reactions leading to life as we know it that can we can demonstrate would occur naturally within the somewhat limited time frame.
No it isn't. It is only an argument against panspermia where the originating body is an Earth like planet. It in no way invalidates - and arguably tends to support - panspermia that sees life originating within GMCs.So, again, Earth itself appeared as soon as possible in the galaxy's development. Well, statistically very early. We've yet to find a system of our own kind so old. But many more will follow. This is a pretty good argument against panspermia.
The real argument against panspermia is that it isn't needed to explain the emergence of life on Earth. If we manage to pin down the time and conditions under which life started on Earth and find that the model doesn't add up, then maybe we need to consider such options. But otherwise they fail Occam's razor and merely push the abiogenesis question to another location.
If the life origin on the earth started by RNA molecules which became enclosed in a membrane and became more complex to form the bacteria - according to the recent theory of evolution. So how did those bacteria live on the earth alone wihout a complete food chain , I mean no equlibrium is established and there is only one way of metabolism directedd towars formation of certain molecules which will deposit on the earth and depends on certain molecule which would be cosumed from the earth ?
The theory of evolution does not deal with the origin of life, it deals with the origin of the variation that emerged from the first cells. That is to say, the origin of species. While the RNA origin of life is certainly one of the more feasible means by which abiogenesis could have occured, there is no one hypothesis that is accepted by the majority of biologists. It's an open question.
No thank you. I'll have to pass on that.
Who says the First Cause is supernatural? Does Aristotle say the First Cause is supernatural? Does the Bible say the First Cause is supernatural? Not to my knowledge. It is not scientific to assume there is no First Cause.
You're right. You could easily argue that. The difference is I have reason to believe in a First Cause. It' called Aristotelian logic.I could as easily argue that the Flying Spaghetti Monster lives in the atmosphere of Neptune.
Incorrect. Just because I can't prove you wrong does not mean what you are saying must be true.You can't prove me wrong so it must be true.
Wrong again. I refer you to Book VIII of Aristotle's Physics. Atheism is absolute illogical and unscientific garbage.When you think about it, the assumption that a God exists is far more likely to be a human invention in reaction to the fear of death and meaninglessness. As a "scientific" explanation it is total garbage since all it does is postpone the question of the beginning of life and matter to "what created God and why", which is invariably answered with the massively unsatisfying concept of a timeless entity without cause. It also adds a layer of complexity to our explanation of the universe- which would only be scientifically acceptable were there evidence that this was required to explain something. It's not required at all.
October 31st, 2008, 01:51 PM
Totally different. Atheism is based upon faith that there is no First Cause. The First Cause is based upon logic and physics.How is this any different from your argument, wherein you claim you know of God's omniscient presence without ever leaving planet Earth or observing more than .0000000001% of the universe?Since you've never left planet Earth or observed even less than .0000000001% of the universe, I take it that you're an omniscient atheist demigod who is infallible.
Ok. so it assumes that the diversity of organisms had emerged from some cells . How could that cells live on the earth without a complete food chain and hence an established equilibrium ?
You seem to be backtracking a bit here now. First Cause is a pretty vague term. You didn't say First Cause, you gave us a link to the Wikipedia article on God and a passage from a Christian psalm.Who says the First Cause is supernatural? Does Aristotle say the First Cause is supernatural? Does the Bible say the First Cause is supernatural? Not to my knowledge. It is not scientific to assume there is no First Cause.
There's a pretty big jump from the philosophical concept of Primum movens to the Judeo-Christian creator God.
I know, I was being sarcastic. I don't actually believe in a Flying Spaghetti Monster. I hope you grasp that.
What? So I say that modern science leaves no gaps of requirement for a creator God as it is described in Genesis etc. and you respond by telling me to read a 2400 year old text on physics?
There are currently-existing single-celled species capable of surviving on nothing more than a mixture of minerals like iron. Many single celled organisms survive on the kind of organic compounds that would have been present in the early Earth environment. Still others derive energy from photosynthesis. None of these requires the presence of other species to survive, just a carbon source and some means of getting energy. Which could also be the carbon source.
Exactly.
I refer you to a 2400 year old text book on physics because you seem to be totally ignorant of basic logic and the principles and history of science.
We know the past MUST be finite because if the past were infinite, time would never arrive a the present.
All things which have a beginning MUST have a cause.
"All the evidence seems to indicate, that the universe has not existed forever, but that it had a beginning, about 15 billion years ago. This is probably the most remarkable discovery of modern cosmology." -- Steven Hawking, The Beginning of Time
So what caused the Big Bang? What caused the universe? The word that physicists have used for over 2000 years is God.
I'm not at all ignorant of Aristotle nor his influence, but you know what? This debate right here is really much too big for the question the OP asked. Feel free to start a new thread on it and I'll debate you there. What's your opinion on the origins of life?Exactly.
I refer you to a 2400 year old text book on physics because you seem to be totally ignorant of basic logic and the principles and history of science.
We know the past MUST be finite because if the past were infinite, time would never arrive a the present.
All things which have a beginning MUST have a cause.
"All the evidence seems to indicate, that the universe has not existed forever, but that it had a beginning, about 15 billion years ago. This is probably the most remarkable discovery of modern cosmology." -- Steven Hawking, The Beginning of Time
So what caused the Big Bang? What caused the universe? The word that physicists have used for over 2000 years is God.
I get what you are saying, but panspermia can become important if it starts to look like it would take a long time for abiogenesis to occur. There can be many reasons for a delayed emergence of life, including the abundance of certain compounds and if a stable enough environment can exist for it to occur. Consequently I am not convinced that we know enough yet to be able to invoke Occam's razor.
On the contrary, I don't think we know enough not to. There's just no indication that we're short on time.I get what you are saying, but panspermia can become important if it starts to look like it would take a long time for abiogenesis to occur. There can be many reasons for a delayed emergence of life, including the abundance of certain compounds and if a stable enough environment can exist for it to occur. Consequently I am not convinced that we know enough yet to be able to invoke Occam's razor.
Well, either way does not interfere with abiogenesis research, so...On the contrary, I don't think we know enough not to. There's just no indication that we're short on time.
There I said "by whatever means", because yes pansperia included. Whatever it was, it didn't waste much time.This is even more suggestive of panspermia, until and unless we have established a wholly plausible suite of prebiotic reactions leading to life as we know it that can we can demonstrate would occur naturally within the somewhat limited time frame.
You're right. I was vaguely thinking of spacefaring aliens, from terrestrial planets.No it isn't. It is only an argument against panspermia where the originating body is an Earth like planet. It in no way invalidates - and arguably tends to support - panspermia that sees life originating within GMCs.
Pansperia could pass too, if we find the right molecules have always been blowing around, persistently seeding Earth throughout its development. That "other location" could be everywhere, all the time. Simple, no?
I'm coming from an infinite universe assumption, so naturally we prove it by adding to the pansperm, ourselves. It is objective to include the likely human destiny in this.
Well it does to an extent as the mechanism of abiogenesis depends on the environment in which life arose. We need to determine that environment.
Even though I don't believe in any god myself, did I ask about god, no! I was wandering about the Origin of life, in a scientific sense.
Unfortunately, the origin of life question invariably turns into a row about religion unless you've got a hardcore science lot debating it.
Thats rather presumptuous considering that there is only one known example of life in the Universe.....Earth.
I'm curious how one can make statistical inferences about the probability or inevitability of life from a sample size of 1?
If I understand my statistics correctly...you can't. Which means we can make no inferences from this one example about the probability of life in the Universe or its formation.
Of course you can extrapolate from 1. If you only know Australia, then you suppose other continents - presuming they exist - are populated by marsupials. If you must presume Australia a special case, because it's also populated by you, then that's something else...Thats rather presumptuous considering that there is only one known example of life in the Universe.....Earth.
I'm curious how one can make statistical inferences about the probability or inevitability of life from a sample size of 1?
If I understand my statistics correctly...you can't. Which means we can make no inferences from this one example about the probability of life in the Universe or its formation.
Yes but on the flip side, we can't see any practical barriers to the emergence of life elsewhere. At the moment we haven't detected any other Earth-like planets but I think we can be quite confident that this will change within the next couple of years.Thats rather presumptuous considering that there is only one known example of life in the Universe.....Earth.
I'm curious how one can make statistical inferences about the probability or inevitability of life from a sample size of 1?
If I understand my statistics correctly...you can't. Which means we can make no inferences from this one example about the probability of life in the Universe or its formation.
As far as general evolutionary science goes, life on earth began from amino acids. Then due to the differnent adaptations for the environment, life was "created". Although I'm quite sure there were no witnesses during earth's creation, I think evolution is slightly more plausible than the idea of God saying "Let there be light!"
But that's just me.
A rather senseless statement, the first part stands in direct contradiction to your earlier claims.
If all you know is Australia and you extrapolate from that, then you will assume that marsupials are quite common.....and you would be wrong.
So if we follow that line and apply it to your earlier assertion about the origin of life being highly probable and perhaps inevitable, then your previous assumptions would most likely be....wrong.
You can extrapolate from a sample size of 1 all you want, but it really is a meaningless extrapolation. Which is why I call your previous claim presumptuous.
Your last statement, I can't really make heads or tails of what you are implying. Is this some lame attempt at a jab at me?
Of course we can think of practical barriers. We understand enough about the basic properties of amino acids, DNA, RNA, fatty acids, carbohydrates, etc to to make all sorts of inferences about the formation of various polymers, enzymatic activity, structures, etc. Theres a reason origin of life research is still pretty much inconclusive. Despite the popularity of ideas like the RNA world, we know pretty much jack. One reason is that it happened so many billions of years ago, but the other is that there are a vast number of practical barriers based on the biochemistry.
This argument is specious.
Occam's razor is a convenient methodological shortcut, it is not an absolute 'law' of how we conduct science. However, let's apply it in this case. Either we postulate a series of complex, heirarchical, interdependent biochemical and prebiotic processes, capable of being implemented in a geologically brief moment on a volumetrically limited substrate, or we expand that time margin by an order of magnitude and the substrate volume by many orders of magnitude.
On this basis, applying Occam's razor, makes panspermia a direct shoo in.
Except that there is no reason to assume that the origin of life needed vast expansions of time.
Of course Occam's razor is not a justification for dismissing a hypothesis outright- perhaps I should have said that it is the reason why panspermia is not widely accepted. In your application of the concept though, you assume that there is some concern that there was not enough time for life to arise on Earth. The likes of Hoyle certainly made that contention, but based that upon some bizarre misunderstandings of how abiogenesis would have been likely to occur.This argument is specious.
Occam's razor is a convenient methodological shortcut, it is not an absolute 'law' of how we conduct science. However, let's apply it in this case. Either we postulate a series of complex, heirarchical, interdependent biochemical and prebiotic processes, capable of being implemented in a geologically brief moment on a volumetrically limited substrate, or we expand that time margin by an order of magnitude and the substrate volume by many orders of magnitude.
On this basis, applying Occam's razor, makes panspermia a direct shoo in.
The reasons why we do not have a theory of abiogenesis is not for lack of our understanding of biochemistry or plausible models- quite the opposite, we have many. The main barrier is our lack of knowledge of the time and location of the event, and thus the starting conditions. But with countless planets outside of the solar system, why would we assume that similar conditions, and thus life, have never existed?Of course we can think of practical barriers. We understand enough about the basic properties of amino acids, DNA, RNA, fatty acids, carbohydrates, etc to to make all sorts of inferences about the formation of various polymers, enzymatic activity, structures, etc. Theres a reason origin of life research is still pretty much inconclusive. Despite the popularity of ideas like the RNA world, we know pretty much jack. One reason is that it happened so many billions of years ago, but the other is that there are a vast number of practical barriers based on the biochemistry.
Yup. I gave you that, in case you'd rather dodge the real argument. Or offer you a chance to show your intellectual honesty.If all you know is Australia and you extrapolate from that, then you will assume that marsupials are quite common.....and you would be wrong.
Other guesses could be right: Birds, grasses, rivers, diamonds, etc.
How many stars can we observe in detail? One. So Sol is probably radically unique among stars and in no way predicts features of them? Meaningless extrapolation?
I could give infinite examples.
Yes, and I should apologize. I'm thinking your refusal to extrapolate from Earth must be guarding Earth's special status in the cosmos. Or maybe you can't reckon Earth life a natural expression of the same laws that govern every bit of the universe. Tell me.
Until a demonstrable process, or suite of processes can be shown not to require large amounts of time there is no reason - other than faith - to assume the reverse.
My view is that we shall likely (80% probability) eventually demonstrate such a suite of processes. But that is largely an opinion. There remains a significant probability that we shall not be able to do so, because that is not how life originates. i.e., while life may be inevitable and commonplace it does not necessarily arise swiftly. We simply do not have enough understanding or even basic data to decide one way or the other at present.
You are assuming a hell of a lot here about what I think or don't think. As for my intellectual honesty, between the two of us, I am being the most honest. I simply am not willing to make grandoise claims that cannot be supported by what we actually know about the origin of life.
You claimed that the evidence argued that life is not only highly probable, but likely inevitable. This is a claim that cannot be upheld based on our vast ignorance of this matter.
My refusal to extrapolate from the Earth is based on the fact that we know next to nothing about this. We have yet to find even another Earth-like planet. No its not impossible for their to be one, but at this point we cannot make reasonable estimations of the likelihood of such planets...let alone the occurance of life.Yes, and I should apologize. I'm thinking your refusal to extrapolate from Earth must be guarding Earth's special status in the cosmos. Or maybe you can't reckon Earth life a natural expression of the same laws that govern every bit of the universe. Tell me.
You misunderstand. I did not say that it is for lack of understanding of biochemistry. On the contrary, I said the exact opposite:
We understand enough about the basic properties of amino acids, DNA, RNA, fatty acids, carbohydrates, etc to to make all sorts of inferences about the formation of various polymers, enzymatic activity, structures, etc. Theres a reason origin of life research is still pretty much inconclusive. Despite the popularity of ideas like the RNA world, we know pretty much jack. One reason is that it happened so many billions of years ago, but the other is that there are a vast number of practical barriers based on the biochemistry.
Since we understand the biochemistry fairly well, we can think of practical barriers to the processes that we know had to occur in order for life to form. You claimed the exact opposite, that no practical barriers can be thought of...which is rubbish.
I see your point now, sorry. I think you've also misunderstood me. For starters I didn't state that we cannot imagine barriers to life emerging elsewhere, of course we can. But we haven't really spotted them in our observations. Are there possible barriers to specific abiogenesis hypotheses? Sure, I wouldn't dispute that for a moment. However, we do know that abiogenesis worked at least once somewhere, if not here. My assertion is that overall there are no barriers to the emergence of life "elsewhere", based upon what we do know. For example, if the universe outside of our solar system appeared to be very different, on average, to conditions here, then that might present a barrier. But by observation is seems it does not differ, in fact the universe appears rather homogeneous. Even with our limited technology, we've already identified over 300 extrasolar planets and the overall trend (taking into account observational bias and our limitations) indicates that our solar system is not unusual by any of the measures we can currently assess.
So, yes we can imagine barriers to the emergence of life elsewhere, but I am contending that we have not observed them.
But are you not also making an unfounded assumption? That abiogenesis required too much time, despite a dearth of information supporting that? I wouldn't rule out panspermia, but it does add a major extra step to a process that hasn't yet been shown to require that step.Until a demonstrable process, or suite of processes can be shown not to require large amounts of time there is no reason - other than faith - to assume the reverse.
My view is that we shall likely (80% probability) eventually demonstrate such a suite of processes. But that is largely an opinion. There remains a significant probability that we shall not be able to do so, because that is not how life originates. i.e., while life may be inevitable and commonplace it does not necessarily arise swiftly. We simply do not have enough understanding or even basic data to decide one way or the other at present.
I think his point is, and I agree with him, is that the process has not yet been shown to not require too much time either. That is why I said it does not affect abiogenesis research really, because we simply don't know enough for it to affect the research. There might even be more than one way for it to develop which allows for both a fast and a slow way. Maybe the next generation of supercomputers might allow for complex enough simulations for us to find out.but it does add a major extra step to a process that hasn't yet been shown to require that step.
I'd imagine there's all manner of genuine possible routes through abiogenesis. Certainly, simulation will help us figure out the starting conditions and chose the likeliest option. We'll probably see some very exciting developments in that regard in the next decade or two.
Anybody please correct me if I'm wrong - I thought our finds of early life are even pushing geology back, so the proto-Earth could not have remained hostile so long as we'd imagined. I mean where once we reckoned a smoldering hell we have cells embedded in rock. If we keep finding life existed sooner than we'd thought possible, not much later than the first solid rock, then apparently life appeared "right away".
I'm open to informed correction.
Not for certain. In an eternal universe panspermia must occur sometimes, so abiogenesis is unnecessary. Though that wouldn't rule out abiogenesis either.
Anyway it's just a matter of time before we ourselves actualize panspermia. In fact we currently take precautions to prevent our panspermia within this solar system and beyond.
But the universe is not eternal. And even if you assume some of the Big Bang models that avoid an absolute beginning, then there is still a finite amount of time since the periods of the universe where the conditions for life are simply impossible. So we are not dealing with an infinite amount of time here, but a finite amount of time and a finite amount of matter and space. So it is not the case that panspermia had to have happened.
On the contrary, I consider it rather ridiculous. The conditions found on an asteroid, comet, whatever, are simply not suitable for the preservation of life...to allow life to traverse from where it originated to Earth. Then there is the problem of how it got on its little vessel to begin with. Where ever life began it would have had to been on a planet with conditions similar to Earth. How did that life form suddenly find itself on some comet or asteroid? How did that organism find itself on a rock that somehow managed to escape the gravitational pull of its home planet and solar system on a trajectory for Earth?
When you think about panspermia to any great extent....its really not that viable. Far more likely that life simply arose on the planet(s) that you find it on and not some other source.
Hi , I'm no scientist or expert in such matters but why do you discount the possibility of extremeophiles travelling to earth on/inside meteorites ? Is it a theory or are there bacteria known to man that can withstand such conditions as inside a meteorite ?
Wasn't the earth itself a hunk of inhospitable chemicals in the beginning with extreme temperatures ?
BARCUD
Yeah sure, that is the panspermia debate. The thing is that those extremophiles also had to originate somewhere, if indeed that is how life came to earth. So even if we were somehow to find out that that is how life came to be on earth, it would still not negate abiogenesis research. In fact, I am pretty sure that more than one mechanism exist whereby life can arise, so research could eventually shine some light on a few of those.
The earth is thought to be about 4.5 billion years old and as far as I know, the earliest signs of life are found in 3.5 to 4 BY old rock. That leaves 500 million to a billion years for it to have emerged. Also, once the first self sustained proto life emerged it would be without rival and could conceivably initially have hugely proliferated before competition for resources had to start and evolution to become needed. This depends of course under what conditions life arose. Who knows, maybe many different forms of proto life arose (well, I think probably) and then a complex mix of symbioses ensured that it stuck.
IMHO
I have to concede those are scientific truths, not religious beliefs. If you are open minded you may see how much religion hinges on this, and how difficult an eternal universe must be for most folks to accept. Enough said.
Alright, let's see how our sample of 1 (Earth) can and inevitably will make it happen, in this finite universe, just for fun...
The conditions are totally suitable. Ever heard of vacuum packaging? Freeze drying? Besides that, space is not a very hostile environment. Seriously. It's a fantastic insulator, so yes technically what little matter the vacuum contains is "cold" but that "cold" does not have much effect on, say, some organisms slowly gnawing at the core of a big snowball. I don't have any numbers for the energy required to to keep liquid water inside a comet (against radiative loss) and that's my fault. But it must be less than accomplished by our little guys that live in icebergs, since conduction isn't happening, and sublimation isn't either (see Saturn's icy rings, non-sublimating). Cold is not a big problem, and a little cold is probably good.
Radiation's not an issue when you're buried under meters of snow, water being an excellent radiation shield.
How did Laika the dog get into space? It was quite a challenge, yes.
Now we have to be a lot more careful, because we're landing probes on comets and soon, moons composed of liquid water. We sterilize this stuff for a reason. But inevitably we will cause extraterrestrial life purposely or not. Exactly how we pan out is up to the imagination. Safe to say we're going to make panspermia a fact at least in this solar system, if we haven't already.
Our stated aim is to spread life throughout the universe, in other words to actualize universal panspermia. We must assume this will happen, or we debate why humanity is doomed to fail in another section of forums.
So there you have it - panspermia is a normal expression of the universe humans are a part of. It's as real as climate change. This "today and tomorrow" panspermia is compatible with abiogenesis as well as any creation beliefs.
There must have been an original act of creation? Well, I had my say at top of this post.
Original life is very theoretical and those theories are diverse but I saw a tv program so I'm going on that :P
Life technically came from comet's but physically began on earth, Comet's contain the 'building blocks of life' the amino acids, and fatty chains, which formed completely coincedentally, as the comet passed a star certain molecules happened to heat together and form little bits of stuff
this lucky comet smashed into earth and some of the bits survived, through utter chance these bits happened to arrive in the right condition and amazingly, formed together in a basic system to increase survivability, and after several million years it developed into something resembling life
I go with this theory because it makes life the luckiest thing ever, since there was like a 1 in 10000000(continue for a bazillion zeros) chance of actually happening
Of course you can blame some dude with too much hair called God
Sounds plausible, though all we really need is for the comets to deposit crude hydrocarbons on Earth in reasonably high concentrations and leave them to it. Since we see plenty of hydrocarbons in the outer solar system, comets are a plausible source of raw materials. That isn't panspermia of course.
Anything that can form on a comet can form on a planet. Decent theories currently under consideration for the formation of organics at alkaline vents, as one example:
http://www.nature.com/nature/links/010712/010712-1.html
and
http://www.nature.com/nrmicro/journa...o1991_BX2.html
and you will have to peruse on your own for more information on this.
Organics most certainly did not need to rain down from outer space, although this certainly happens.
So vise versa, right? If the early solar system had a multitude of large watery asteroids/planetoids in every orbit conceivable, surely some if not most contained gradients of warm water and many occupied a "sweet spot" if we can define that. How is this less hospitable to life than Earth? It seems these bodies had the statistical advantage in every way.
If you're not too specific about the planet or the comet, maybe. But can anything that forms on a long period comet also form on Earth? The conditions are very different, even just looking at the basics such as starting materials, temperature variations and atmospheric pressure.
That doesn't mean we needed a comet borne contribution for life to start here, but I'd be surprised if it didn't happen anyway.
They are less attractive in terms of energy gradients, as I understand it, which are necessary for forming carbon-carbon bonds. Hydrothermal vents provide redox gradients and cold alkaline vents form osmotic as well as pH gradients, if memory serves.
I was thinking that a multitude of asteroids have better collective odds of hitting a nice rate and degree of days and seasons, more so than arbitrary Earth. For example if life prefers an 80 hour day, it's got it. Anyway with planetoids the size of our surviving water moons there is convection stirring things up. I assume (vaguely) life more likely in a cyclic environment.They are less attractive in terms of energy gradients, as I understand it, which are necessary for forming carbon-carbon bonds. Hydrothermal vents provide redox gradients and cold alkaline vents form osmotic as well as pH gradients, if memory serves.
I agree a terrestrial surface offers sharper gradients... though on a scale much larger than our teams of molecules. Wouldn't weightless muck and boulders milling through microgravity convections do the trick as well?
Is gravity necessary or even helpful for abiogenesis?
Gravity, temperature and a reasonable atmospheric pressure would be needed I think. The kinds of chemical reactions that are cited in most abiogenesis models need to happen in solution, i.e. in liquid water.I was thinking that a multitude of asteroids have better collective odds of hitting a nice rate and degree of days and seasons, more so than arbitrary Earth. For example if life prefers an 80 hour day, it's got it. Anyway with planetoids the size of our surviving water moons there is convection stirring things up. I assume (vaguely) life more likely in a cyclic environment.They are less attractive in terms of energy gradients, as I understand it, which are necessary for forming carbon-carbon bonds. Hydrothermal vents provide redox gradients and cold alkaline vents form osmotic as well as pH gradients, if memory serves.
I agree a terrestrial surface offers sharper gradients... though on a scale much larger than our teams of molecules. Wouldn't weightless muck and boulders milling through microgravity convections do the trick as well?
Is gravity necessary or even helpful for abiogenesis?
How's that? Early life didn't walk. In fact neutral buoyancy is preferable isn't it?
If the system began as hot nebula, raining into solids, I think the first cool environment would be beneath ice shell of watery planetoid. Anyway, we have proven bathwater temperatures in our surviving example, Europa, since we observe geysers breaching frozen crust.
Or pressure of ocean. You may have that in a watery asteroid, with depth, or even pressing out against the crust. I don't see how pressure helps though.
More of that in space than on Earth.
I think a main requirement is for the build block containing soup has to be fairly undisturbed for the required chemical reactions to be able to take place. An open ocean might not provide such an environment. So it would require standing pools maybe, which would evaporate under low atmospheric pressure. IMHO :?
Gravity allows a stable atmosphere and liquid water on the surface, at least on Earth. How do you get neutral buoyancy if you don't have a liquid to float in? Earth gravity certainly doesn't negatively impact on that for single celled life anyway.How's that? Early life didn't walk. In fact neutral buoyancy is preferable isn't it?
The case for liquid water beneath the surface of Europe is not confirmed. I've never heard of such geysers being observed on that body, do you have a source on that? I do reckon there is liquid water there, but that is not proven at this time, as far as I am aware. Were you thinking of Titan? There's cryovolcanism involving liquid water there and it's certainly an excellent place to look for life.If the system began as hot nebula, raining into solids, I think the first cool environment would be beneath ice shell of watery planetoid. Anyway, we have proven bathwater temperatures in our surviving example, Europa, since we observe geysers breaching frozen crust.
Atmospheric pressure helps keep water liquid at surface level, and thus exposed to comet impacts and other fun stuff whilst reducing ionizing radiation and the general loss of water to space.Or pressure of ocean. You may have that in a watery asteroid, with depth, or even pressing out against the crust. I don't see how pressure helps though.
Earth is in space, as are Titan, Europa, Enceladus etc. I was talking about comets though, and there is certainly not more liquid water in those than there is here. More ice? Surely. But when heated in the absence of the pressure provided by an atmosphere (due to gravity), ice sublimates directly into vapour. I've never heard of any evidence of liquid water persisting on or within a comet or asteroid. That's not to say that this is impossible.More of that in space than on Earth.
Low atmospheric pressure probably not, as this will cause your water boil off at relatively low temperatures. I think some of the hypotheses on abiogenesis would favour the standing pools though. Certainly, strong water currents could hardly be good for the reactions unless the hydrocarbon concentrations were very high indeed.
The alkaline vents at the Lost City (mentioned earlier) form inorganic chambered chimneys which allow the sort of compartmentalisation you are thinking of.
See Figure 1 here:
http://www.molevol.de/publications/135.pdf
The inorganic compartments have been replicated at the bench under simulated vent conditions. In addition, the presence of venting fluid allows continual gradients to drive chemical reactions.
And I came across the following as well which looks intriguing but I can't be bothered to read it, sorry 'bout that, about to go plop down in front of the telly.
http://www.funpecrp.com.br/GMR/year2..._full_text.htm
Granted, just what mass of those moons is liquid now we don't know. So there's no proof the bulk of (non-hostile) liquid water is extraterrestrial. I should have said around the time of genesis. If the Earth's water owes to random collisions with watery bodies, their collective mass must have been some orders of magnitude greater than Earth's oceans. Like, how much rain does a served tennis ball pick up vs. how much is raining in the court? Sure the system's clear and sunny now.Earth is in space, as are Titan, Europa, Enceladus etc. I was talking about comets though, and there is certainly not more liquid water in those than there is here. More ice? Surely.More of that in space than on Earth.
That's the surface-dweller talking. You want liquid or solid below, and gas retained above. But abiogenesis doesn't need it... that may even be a bad setting. Radiation shielding and (atmospheric) pressure occurs easily with weight of ice and water above, even on a small body. Have any pressure you like in this case.
I was wrong: we have not observed geysers on Europa. Just features that could suggest geysers in the past.
Subsurface liquid water is logical however. The tectonic instability of Europa's crust is accepted. The simplest explanation has this frozen crust floating on a molten layer of the same stuff - water. What other molten layer can you float ice upon that doesn't result in some liquid water? The depth of that (mantle) is unknown, but since we do know Europa's overall density we can guess it's very deep, roughly comparable to Earth's upper mantle.
For energy gradient. Presumably at divergent plate boundaries there would be a steady flow of warmer water (Europa's version of magma), somewhat like our Earth's hydrothermal vents as far as life's concerned... except, ironically, those conditions may be less "exotic" in terms of temperature and chemistry than Earth's. Another source of gradient is through convection currents, which I think are more dramatic where low gravity/buoyancy allows water phase change to form gross topographies (e.g. it takes very little current in Europa to carve a stalactite or undertow an iceberg).
As we know some Europa-like and smaller watery bodies collided with Earth, bringing water and complex organics necessary to life, before and around the time life is first found in Earth. Why stop there? Isn't it much simpler to assume life started where conditions were more probably good already? I appreciate the assumption that Earth, then, must have offered a good environment, but I can't help noticing the circular logic either. Earth abiogenesis now seems to be trying to simulate terrestrially the conditions that most probably existed extraterrestrially.
Geysers have been observed on Enceledus.
Liquid water on Europa is almost certain. An easy watch:
http://www.youtube.com/watch?v=3Wt2ozivmKU
I agree, there's tons of water out there. Just questionable as to how much of it is liquid and how much of it is accessible to contamination from random organic compounds. The oceans of Earth had all kinds of stuff raining down into them when the solar system was still young. Now somewhere like Titan, you've got tons of organics in the atmosphere and on the surface.... extensive cryovolcanism will gradually mix that stuff up with the subsurface liquid water/ammonia layer so that's another good candidate site for abiogenesis.Granted, just what mass of those moons is liquid now we don't know. So there's no proof the bulk of (non-hostile) liquid water is extraterrestrial. I should have said around the time of genesis. If the Earth's water owes to random collisions with watery bodies, their collective mass must have been some orders of magnitude greater than Earth's oceans. Like, how much rain does a served tennis ball pick up vs. how much is raining in the court? Sure the system's clear and sunny now.Earth is in space, as are Titan, Europa, Enceladus etc. I was talking about comets though, and there is certainly not more liquid water in those than there is here. More ice? Surely.More of that in space than on Earth.
You are bringing me around to the notion of abiogenesis on a comet, the numbers involved make sense.
Again though, I'd wonder about access to that water. If the body itself lacks carbon, having exposed surface liquid water opens the door for collisions that will introduce the required material. That said, on a body like Titan there's no shortage of both, and there's a system in place to mix them. On a comet, the periodic brushes with the sun might allow mixing too...That's the surface-dweller talking. You want liquid or solid below, and gas retained above. But abiogenesis doesn't need it... that may even be a bad setting. Radiation shielding and (atmospheric) pressure occurs easily with weight of ice and water above, even on a small body. Have any pressure you like in this case.
Absolutely, and I'm confident we'll confirm liquid water on Europa some day. It's another great candidate site for life. Though the radiation levels generated by Jupiter may make Saturn's moons a safer bet.I was wrong: we have not observed geysers on Europa. Just features that could suggest geysers in the past.
Subsurface liquid water is logical however. The tectonic instability of Europa's crust is accepted. The simplest explanation has this frozen crust floating on a molten layer of the same stuff - water. What other molten layer can you float ice upon that doesn't result in some liquid water? The depth of that (mantle) is unknown, but since we do know Europa's overall density we can guess it's very deep, roughly comparable to Earth's upper mantle.
You are starting to convince me. I'm not at all closed to the possibility I should say, but more dubious about the need for extraterrestrial abiogenesis as an explanation of life here. We haven't demonstrated a need, a gap in our models, that requires that step.
woah, Very interesting stuff here guys, its really enlightened me
The answer to "the origin of life" question will be religious, either God or Evolution, there is no physical proof either way. You will have to have faith to believe either one. No one knows for sure, no one was there, fossils tell us only that they died. Scientist will go only so far honestly before the fear of their money being pulled if they follow the evidence.Unfortunately, the origin of life question invariably turns into a row about religion unless you've got a hardcore science lot debating it.
1. The theory of evolution does not involve the emergence of life, it involves the emergence of variation in life. Hence the title of Darwin's book. "The Origin of Species", not "The Origin of Life".
2. Evolution requires absolutely no faith-based assumptions. It is 100% testable and can hypothetically be proven wrong by experimentation. Thus it is nothing like a religion.
There's plenty of evidence in support of the theory of evolution. There is less in support of any specific abiogenesis hypothesis, but that certainly does not mean there is none.
Scientists don't assume either case to be true. Faith implies belief in the absence of evidence. Scientists believe based upon evidence. That is why evolution is considered a solid theory but abiogenesis is treated with greater caution. If we had faith as you are suggesting, we'd just believe in abiogenesis without doing any more research.
Nothing to do with the origin of life. The fossil record supports common descent.
You just claimed there was no physical evidence either way. I suppose you're trying to imply that scientists are afraid to look at "evidence" for Creation for fear of losing their funding. Please.
A research paper that could actually demonstrate such evidence (and do so conclusively) would be massively controversial- which would be a career-making move for any scientist.
Besides, there are plenty of "research" groups who could fund such work very very well indeed. The Discovery Institute, Answers In Genesis. These groups make millions of dollars per year in donations alone. What do they spend that money on? Not primary research oddly enough. The money is there. It's being spent on a propaganda war designed to sell books with no evidence in them.
What fossle record would you be talking about and how could that explain evolution from one species to another, there is no evidence of this, so one would have to imagine this occuring, hence faith.
Why is the science community so hell bent on making sure that evolution is taught in school without any reference to other ideas?
The fossil record contains many intermediate forms, which were predicted and subsequently found. Since every generation is an intermediate, there will always be intermediates that are not represented in the record simply because they were not preserved. However, intermediates continue to be found.
Put another way, science predicts that some intermediates will be found but that not all have been preserved, and this is what is seen.
Another way to look at the fossil evidence is that we predict that latecomers to the tree of life (such as great apes) will not exist in the fossil record before a certain age. We predict that we will never find a human fossil in the same geological strata as a T. rex. We can make this sort of prediction for virtually any fossilisable animal or plant.
The prediction holds up.
As to what is taught in science, you have it a bit back to front if you don't mind me saying so. It is not that a group of people decided that evolution would be taught come hell or high water. Rather, the teaching of (and adherence to) science and the scientific method involves anlaysis of evidence that leads to only one tenable conclusion for the origin of species: evolution, which is constantly modified as additional data pours in. Evolution is the end point of our understanding, not the beginning.
To put biblical stories on equal footing, one would need to make predictions that hold with biblical theory. For example, one would need to predict that at the time of the flood, there was a genetic bottleneck for every species, a time during which only two members from each species were rescued from certain death. Given such a genetic bottleneck, the prediction would be for a certain genetic limitation (lack of diversity) among the descendants of these pairs of animals.
If it were found that all humans were so similar in DNA that they must have derived from a single family (Noah's), then there would exist scientific testing and evidence of the story of the flood. That would give the flood story some footing in a science classroom.
But since this is not what is found, the story of the flood cannot be said to hold up to the scientific method, and belongs in other disciplines such as religious studies.
Free radical explains it quite well above. The morphology of the fossils we find represent transitions between the morphologies of other species, both living and extinct. We can measure the age of these fossils. Taken as a whole, the shape and age of the known fossils agree with what we'd expect to find if evolution were correct.
Let's try an analogy. Imagine we have a graph, a scatter plot. We're measuring something and adding data points to the graph. Just points, each with an x and y value. After our first three points, we can see that the points appear to be forming a diagonal line. We don't have enough information to conclude that this really the case, so we say that we have a hypothesis. We have a trend line on our graph that may be a model of reality. There are still plausible alternative hypotheses at this stage; the three points could be part of a large gradual curve, or new data might show us that there's no simple connection between the points at all.
But as we add more points to the graph, we can be more and more sure that our "hypothesis of the line" is a model of reality. Eventually, we have so much data that we can say beyond all reasonable doubt that the trend line is an accurate model of reality. It is no longer a hypothesis, it is now a theory.
Of course it's still conceivable that we could prove our model wrong. When we only had three points, we could have falsified our model with a single point out of place. Now, with thousands of points in our graph all lined up, we'd need a lot more contradictory data to falsify our model.
Sorry man, but evolution is just as the theory I described above. We have thousands upon thousands of fossils all exactly where we'd expect to see them. We have DNA analysis that works both chronologically and in terms of lineage that shows that all life we have examined has a common ancestor. We have tons of evidence from species still living too. And nowhere in all of that evidence, do we find the data, the outliers, the contradictions that would suggest to us that our model, the theory of evolution, is inaccurate.
There's no faith here, we are literally just describing what the evidence shows us and no more.
And how many would we teach? Just young Earth creationism? What about ID? How about old Earth creationism? Or Buddhist, Muslim, Hindu, Wiccan and Norse creationism? There's no end to the fringe options, and yet none of them is supported by simple observation. Evolution, by distinct contrast, is a theory as firmly tested and as widely accepted as general relativity. The data fits effortlessly into the model (if it did not we'd have to abandon the model). It is a representation of fact, so naturally we would teach it as such. As to the alternatives, they are not supported by the evidence at all.
Ok, if you had to pick the fossle that best helps your case of evidence for evolution from one species to another, what is it?
You didn't quite follow the scatter plot analogy, did you mate?
Which of the points on the above curve is the best evidence that the data follow a curve?
Cheers,
FR
You didn't quite follow the poor grammar of mastmec?You didn't quite follow the scatter plot analogy, did you mate?
Here it is again: OK, if you had to pick a fossil lineage that best helps your case........?
As FR says, no one fossil stands as evidence of evolution. Any more than a single dot on a join-the-dots picture allows us to know what the picture is. The totality of the fossil record is what seals the deal. Some of the fossils alone do falsify the baramin hypothesis (and thus creationism) though.
Which case? The occurrence of speciation? Last I checked, not even the creationists questioned such "micro-evolution" as they would term it.You didn't quite follow the poor grammar of mastmec?You didn't quite follow the scatter plot analogy, did you mate?
Here it is again: OK, if you had to pick a fossil lineage that best helps your case........?
I am afraid I don't follow you at the moment. All lineages can be used to demostrate evolution and I don't have a particular favourite.You didn't quite follow the poor grammar of mastmec?You didn't quite follow the scatter plot analogy, did you mate?
Here it is again: OK, if you had to pick a fossil lineage that best helps your case........?
Pterodactyls sure capture the imagination tho.
poor grammar or not, that's NOT what mastmec said - he clearly said "pick the fossil", NOT "pick the fossil lineage", the difference between the 2 is not one of grammar
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