APOD and General Astronomy Discussion Forum
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No life has been identified that isn't carbon-based.Nitpicker wrote:See:
http://en.wikipedia.org/wiki/Hypothetic ... ochemistry
Silicon (just below Carbon in the periodic table) based life forms would seem to be the most likely alternative. (I have a vague memory of such a life form being discovered in some deep sea vent on Earth, but maybe that was fiction.)
Here's another thought, although I'm not sure what the general consensus regarding this hypothesis is.Nitpicker wrote:See:mjimih wrote:So...
Does the periodic table (which is the same table used by all aliens, everywhere), give up any clues about whether there are potentially other ways to create life besides "carbon based"? The answer will help us to know more about what to look for in potential habitable planet candidates.
http://en.wikipedia.org/wiki/Hypothetic ... ochemistry
Silicon (just below Carbon in the periodic table) based life forms would seem to be the most likely alternative. (I have a vague memory of such a life form being discovered in some deep sea vent on Earth, but maybe that was fiction.)
Yup, I think my brain confused reality with an episode of the X-files.Chris Peterson wrote:No life has been identified that isn't carbon-based.
I can't discuss the visceral part of yourself, but you are mistaken if you think that I don't want scientists to do their very, very best to understand life on Earth and to understand the number and nature of planets far from our solar system.Geckzilla wrote:
Maybe that's the point you are trying to make--that it is impossible and hopeless to even try looking--and all I can do is disagree from a very visceral part of myself.
to devolve into?Ann wrote: This is the sort of thing that I don't want the field of astronomy to evolve into.
Ann
I must admit I don't lose much sleep over that. Crackpots are everywhere, but still rare enough. But please wake me when the aliens start preaching from the pulpit.Ann wrote:But I must say that when I listened to the astronomer presenting his book to us, I sometimes felt as if I was listening to a sermon from a pulpit where I was being asked if my faith in life in space was strong enough.
This is the sort of thing that I don't want the field of astronomy to evolve into.
Nitpicker wrote:I must admit I don't lose much sleep over that. Crackpots are everywhere, but still rare enough. But please wake me when the aliens start preaching from the pulpit.Ann wrote:But I must say that when I listened to the astronomer presenting his book to us, I sometimes felt as if I was listening to a sermon from a pulpit where I was being asked if my faith in life in space was strong enough.
This is the sort of thing that I don't want the field of astronomy to evolve into.
Oh, I wouldn't necessarily expect the aliens to be religious. I just anticipate a few cultural misunderstandings. Either way, I'd want to hear what they have to say.Ann wrote:I will, Nitpicker. At least then we'll know for sure that there are intelligent - make that technologically advanced and religiously inclined - aliens in our galaxy.
Assuming you can hear them.Nitpicker wrote:Oh, I wouldn't necessarily expect the aliens to be religious. I just anticipate a few cultural misunderstandings. Either way, I'd want to hear what they have to say.Ann wrote:I will, Nitpicker. At least then we'll know for sure that there are intelligent - make that technologically advanced and religiously inclined - aliens in our galaxy.
Given the relative abundance of elements in the the Universe, it is hard to imagine that life anywhere would be based on anything but, hydrogen, oxygen, carbon, and nitrogen. Ignoring the noble gases helium and neon, they are 4 of the 5 most abundant elements in the Universe, with iron being the other.mjimih wrote:I asked earlier, but not very well. Um does the periodic table give up any clues about whether there are potentially other ways to create life besides "carbon based"? And if so, someday after more research, we shall be looking for a wider variety of exo-planet types that may be habitable hopefully. Not just temperate rocky water-laden ones like Earth.
Right now science (a scientist) is a-stir about Titan's oceans harboring life. We also found mystery bubbles in the rocks on Mars. I also heard that a planet with free oxygen in an atmosphere, is a sign of life possibly.
My point is we shouldn't keep our ET search too limited. We must be creative (Einstein comes to mind). We are assuredly not the ONLY kind of life. We are Earth life. And I predict it will be exceedingly difficult to spot life's signs in an exo-atmosphere, simply because of just the sheer number of types out there that we haven't even a clue about. And the distances.
So...
Does the periodic table (which is the same table used by all aliens, everywhere), give up any clues about whether there are potentially other ways to create life besides "carbon based"? The answer will help us to know more about what to look for in potential habitable planet candidates.
Mark
Nitpicker wrote:See: http://en.wikipedia.org/wiki/Hypothetic ... ochemistrymjimih wrote:
Does the periodic table (which is the same table used by all aliens, everywhere), give up any clues about whether there are potentially other ways to create life besides "carbon based"? The answer will help us to know more about what to look for in potential habitable planet candidates.
Silicon (just below Carbon in the periodic table) based life forms would seem to be the most likely alternative. (I have a vague memory of such a life form being discovered in some deep sea vent on Earth, but maybe that was fiction.)
stephen63 wrote:
Here's another thought, although I'm not sure what the general consensus regarding this hypothesis is.
http://en.wikipedia.org/wiki/Shadow_biosphere
I don't find that a convincing argument. I see no reason that life couldn't be based on trace elements (certainly, life on Earth is very dependent on them).bystander wrote:Given the relative abundance of elements in the the Universe, it is hard to imagine that life anywhere would be based on anything but, hydrogen, oxygen, carbon, and nitrogen. Ignoring the noble gases helium and neon, they are 4 of the 5 most abundant elements in the Universe, with iron being the other.
BMAONE23 wrote:
Can't forget about Phosphorus. Without that Deoxyribose & associated Phosphate molecule binding the ladder together, DNA tends to want to unravel
http://en.wikipedia.org/wiki/Phosphorus wrote:<<Phosphorus was the 13th element to be discovered. For this reason, and also due to its use in explosives, poisons and nerve agents, it is sometimes referred to as "the Devil's element". It was the first element to be discovered that was not known since ancient times. The discovery of phosphorus is credited to the German alchemist Hennig Brand in 1669. Brand experimented with urine, which contains considerable quantities of dissolved phosphates from normal metabolism. Working in Hamburg, Brand attempted to create the fabled philosopher's stone through the distillation of some salts by evaporating urine, and in the process produced a white material that glowed in the dark and burned brilliantly. It was named phosphorus mirabilis ("miraculous bearer of light"). His process originally involved letting urine stand for days until it gave off a terrible smell. Then he boiled it down to a paste, heated this paste to a high temperature, and led the vapours through water, where he hoped they would condense to gold. Instead, he obtained a white, waxy substance that glowed in the dark. Brand had discovered phosphorus. We now know that Brand produced ammonium sodium hydrogen phosphate, (NH4)NaHPO4. While the quantities were essentially correct (it took about 1,100 L of urine to make about 60 g of phosphorus), it was unnecessary to allow the urine to rot. Later scientists discovered that fresh urine yielded the same amount of phosphorus. The secret that it was made from urine leaked out and first Johann Kunckel (1630–1703) in Sweden (1678) and later Boyle in London (1680) also managed to make phosphorus. Boyle states that Krafft gave him no information as to the preparation of phosphorus other than that it was derived from "somewhat that belonged to the body of man". This gave Boyle a valuable clue, so that he, too, managed to make phosphorus, and published the method of its manufacture.>>Click to play embedded YouTube video.
Should have called it uranium, or maybe urinium.neufer wrote:http://en.wikipedia.org/wiki/Phosphorus wrote: Brand experimented with urine, which contains considerable quantities of dissolved phosphates from normal metabolism. Working in Hamburg, Brand attempted to create the fabled philosopher's stone through the distillation of some salts by evaporating urine, and in the process produced a white material that glowed in the dark and burned brilliantly. It was named phosphorus mirabilis ("miraculous bearer of light").
Chris Peterson wrote:Should have called it uranium, or maybe urinium.neufer wrote:http://en.wikipedia.org/wiki/Phosphorus wrote:
Brand experimented with urine, which contains considerable quantities of dissolved phosphates from normal metabolism. Working in Hamburg, Brand attempted to create the fabled philosopher's stone through the distillation of some salts by evaporating urine, and in the process produced a white material that glowed in the dark and burned brilliantly. It was named phosphorus mirabilis ("miraculous bearer of light").
http://en.wikipedia.org/wiki/Porphyria wrote: <<The porphyrias are a group of rare inherited or acquired disorders of certain enzymes that normally participate in the production of porphyrins and heme. The term porphyria is derived from the Greek πορφύρα, porphyra, meaning "purple pigment". The name is likely to have been a reference to the purple discolouration of feces and urine when exposed to light in patients during an attack.
The mental illness of George III is the basis of the plot in The Madness of King George, a 1994 British film based upon the 1991 Alan Bennett play, The Madness of George III. The closing credits of the film include the comment that the illness suffered by King George has been attributed to porphyria and that it is hereditary. Among other descendants of George III theorised by the authors of Purple Secret to have suffered from porphyria. In 2
Note: There might be an audio player above this text. If not, click here to download the file.005 it was suggested that arsenic (which is known to be porphyrogenic) given to George III with antimony may have caused his porphyria. It is believed that Mary, Queen of Scots – King George III's great-great-great-great-great-grandmother – also suffered from acute intermittent porphyria, although this is subject to much debate. It is assumed she inherited the disorder, if indeed she had it, from her father, James V of Scotland; both father and daughter endured well-documented attacks that could fall within the constellation of symptoms of porphyria.
Vlad III was also said to have suffered from acute porphyria, which may have started the notion that vampires were allergic to sunlight.
Other commentators have suggested that Vincent van Gogh may have suffered from acute intermittent porphyria. It has also been speculated that King Nebuchadnezzar of Babylon suffered from some form of porphyria (cf. Daniel 4).>>
Of course, because we know what to look for there. The limitations are largely technical ones, and technical limitations to get reduced over time.mjimih wrote:Let's look at stable/old, warm n rocky ones, with water first.
.It's a good argument, but far from perfect. What we don't, in fact know, is how many times life separately developed and died out. We don't know that because we have only the sparsest of physical evidence of anything on the Earth during its first billion years. It may well be that the conditions that make it easy for life to form were only found in that early environment. If so, that should increase the likelihood of life forming on other planets.robgendler wrote:Sorry to resurrect this thread but I had a thought which I believe is pertinent to the discussion. It is universally agreed that all living organisms on earth share a common ancester which existed somewhere around 3.8 billion years ago. There is no fossil or molecular evidence of any separate origin of life after this event. This very basic life form gave rise to all future life on our planet. We do know that conditions on the young earth changed fairly rapidly in the first billion years with rapid cooling and formation of oceans, atmosphere, etc. The important point here is that life began only once during the course of 4.5 billion years on a planet with an early history of fairly dramatic geologic and atmospheric change. If the origin of life is to be considered a common event in the universe (occurring under a variety of conditions), then it should have evolved multiple times on our own planet given the huge variety of geologic and atmospheric changes that have occurred on earth over geologic time periods. However it is striking that as far as we know life has not had multiple origins. The obvious conclusion is that the formation of life from organic compounds requires a very strict set of conditions which occurred once and these very specific conditions did not last very long during the early period in our planets history. This very considerably narrows the window of conditions from which life will form from organic compounds IMO. If.... as was said by several others in this thread.... that life might very well form in any combination of geologic conditions....then it should have formed again and again and again during the long history of our planet. Certainly earth has offered up an immense range of different environmental conditions during 4.5 billion years...but yet life began only one time. This should IMO temper the enthusiasm for a "universe teaming with life". Anyway feel free to fire away at this deductive reasoning :-).
stephen63 wrote:
Paul Davies pondered just that: http://www.nytimes.com/2013/11/19/opini ... .html?_r=0
Might we have Alien "Intelligence" within our own midstPaul Davies is the director of the Beyond Center for Fundamental Concepts in Science at Arizona State University and the author of “The Eerie Silence: Renewing Our Search for Alien Intelligence.”
