APOD: Kepler 78b: Earth Sized Planet... (2013 Nov 05)

[Chris Peterson]

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.)

No life has been identified that isn't carbon-based.

[stephen63]

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.

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.
http://en.wikipedia.org/wiki/Shadow_biosphere

[Nitpicker]

No life has been identified that isn't carbon-based.

Yup, I think my brain confused reality with an episode of the X-files.

But I mentioned it anyway, in case some expert on deep sea vents (who just happens to like looking at astrophotographs [possibly an astrobiologist]) would tell us all something interesting about them.

[mjimih]

After reading that wiki article, I'm thinking we are maybe the coolest life forms around. And much more common than any of our hot neighbors might be. The good thing is, we are more likely to find life like us because the periodic table seems to be fairly limited in the tricks it can use to make life similar to us with any of the alternate ingredients. yippie! i guess.

[Ann]

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.

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.

But I think that there is a lot of wishful thinking in today's discussion about life away from the Earth. I recently attended a lecture where a professional Swedish astronomer talked about his book about life in space. By his own admittance, this astronomer is not a biologist at all, and he had to seek help to find the facts about biology that he needed to write his book. Of course there is absolutely nothing wrong about seeking help from others. But my impression, when I listened to this lecture, was that the astronomer was actually pleading with his audience, made up of members of an astronomy club, to please believe in life in space. He clearly wasn't talking primarily about simple alien life forms, either. Instead, he repeatedly showed us illustrations from his book of properly alien-looking humanoids. Toward the end of the lecture the astronomer turned to the only other professional astronomer in the audience and asked him his opinion about the beliefs of astronomers in general. Do they believe in life in space or don't they? Do they poll one another to find out what they believe as a community?

There has been talk about the difference between faith and science earlier in this thread, a discussion that I have not been a part of. 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.

Ann

[mjimih]

And interestingly enough, any life spotted will have been entirely dependent on the planet's characteristics in form and type. If we find that 20% of sun-like stars have habitable planets, I bet if that's true, most better be very similar to Earth or we won't find much due to the fact that the periodic table's chemistry is sort of rigid in terms of it's ability to make "earthlings" with alternate ingredients.

[mjimih]

This is the sort of thing that I don't want the field of astronomy to evolve into.

Ann

to devolve into?

Maybe he just wants to reaffirm to himself and to the audience, eagerly, that there is a consensus amongst astronomers that there is most likely lots of life out there, as he believes. As evidenced by his book and illustrations.

[Nitpicker]

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.

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]

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.

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.

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.

Ann

[Nitpicker]

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.

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.

[geckzilla]

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.

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.

Assuming you can hear them.

[bystander]

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

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.

[neufer]

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.

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.)

• . http://www.universetoday.com/91449/

Here's another thought, although I'm not sure what the general consensus regarding this hypothesis is.
http://en.wikipedia.org/wiki/Shadow_biosphere

[Chris Peterson]

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.

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).

I think it is reasonable to believe that life which develops in a certain environmental envelope, which includes our own, will be based on the elements you list, and will utilize biochemical pathways similar or identical to those we observe on Earth. But what about radically different environments? What about the surface of icy bodies, or deep inside planets, or the bottom of extremely deep oceans (including oceans of something other than water)? I see "life" as nothing more than spatially confined organized chemical reactions, with sufficient information storage to replicate. That seems like something that could occur with radically different chemistries than we associate with life. (Again, I'm not suggesting complex life forms, or animals. It's very possible that those would have metabolic requirements that considerably narrow the range of possible chemistries.)

I should point out that these kinds of questions represent one area being explored by astrobiology, and a knowledge of biology is of no particular advantage. This is more about physical chemistry than anything else.

[BMAONE23]

Can't forget about Phosphoros. Without that Deoxyribose & associated Phosphate molecule binding the ladder together, DNA tends to want to unravel

[neufer]

Can't forget about Phosphorus. Without that Deoxyribose & associated Phosphate molecule binding the ladder together, DNA tends to want to unravel

Click to play embedded YouTube video.

<<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.>>

[Chris Peterson]

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").

Should have called it uranium, or maybe urinium.

[mjimih]

Chris wrote; "But what about radically different environments? What about the surface of icy bodies, or deep inside planets, or the bottom of extremely deep oceans (including oceans of something other than water)?"

that's precisely where I was going. When we start getting clues as to what to look for, keeping our eyes wide open, I think scientists will have a ton fun with it.

"I see "life" as nothing more than spatially confined organized chemical reactions, with sufficient information storage to replicate."

And an extraordinary amount of time, billions, for the environment to create it too. In most cases the really complex ones' (Earth) fail imo. Hey! we need more extra sensitive instruments made as soon as possible. Let's look at stable/old, warm n rocky ones, with water first.

[neufer]

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").

Should have called it uranium, or maybe urinium.

• Or Porphyrias instead of Phosphorus:

[b][color=#008F8F]George's Star's blue-green coloration results from the absorption bands of methane.[/color][/b]

---

<<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).>>

[Chris Peterson]

Let's look at stable/old, warm n rocky ones, with water first.

Of course, because we know what to look for there. The limitations are largely technical ones, and technical limitations to get reduced over time.

It will be the job of some astrobiologists to elucidate possible non-organic chemistries that could be used by life. And assuming they identify alternate chemistries, that will provide new things for the observers to seek out.

[robgendler]

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 .

[Chris Peterson]

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 :-).

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.

Also, I'd say your assertion that all living organisms on Earth share a common ancestor being a matter of universal agreement is overstated. It's a reasonable and widely held assumption, but not everybody believes it is certain, and there is good solid science still being directed at that question. One line of evidence suggests that life poisons the conditions for the development of new life.

Lots of research opportunities left in this field!

[stephen63]

Paul Davies pondered just that.
http://www.nytimes.com/2013/11/19/opini ... .html?_r=0

[robgendler]

"If microbial life is widespread in the cosmos, we can expect that, at least here and there, sentient beings will evolve. We would then be much closer to answering that age-old puzzle of existence: Are we alone in the universe? "

Good article...except for the above grossly determistic assumption. If intelligence is highly selected for (inevitable sentient beings) then answer me the following. Arguably the second most intelligent animal on earth (the chimpanzee) has not been even remotely as successful as man from an evolutionary perspective. Also there is good evidence for the existence and subsequent extinction of multiple hominid species, all highly intelligent and likely highly conscious beings. The highly intelligent marine mammals although successful in their own way are not any more successful than sharks.....a primitive group having shown little change over 400 million years. The article was great until his last sentence which reveals obvious anthropogenic thinking and bias.

[neufer]

Paul Davies pondered just that: http://www.nytimes.com/2013/11/19/opini ... .html?_r=0

Paul 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.”

Might we have Alien "Intelligence" within our own midst