Non-Carbon-Based Life

[Teoman2]

I vote Iron because somewhere out there, there might be a "Iron" Man!

[phoenix_ca]

There's the far more interesting question of whether or not life could exist in entirely different ways. Solaris pondered what it might be like to try and communicate with a truly alien life (one made of plasma O.o ).

[JMBuilder]

Here's an entirely different idea. What about vanadium-based life? It's a versatile metal capable of forming all kinds of oxides and complex structures. Life based on it would exist in a much hotter climate.

[itstimaifool]

Advance note: I fully expect to have many logical errors in the following post. I am not an expert in anything related to this topic, and my only qualification for posting here is an interest in science fiction. That being said, I welcome constructive criticism from someone more informed than me.

There's the far more interesting question of whether or not life could exist in entirely different ways. Solaris pondered what it might be like to try and communicate with a truly alien life (one made of plasma O.o ).

This is what I was thinking as I read this thread. I mean, everyone has had some very interesting and informative opinions on different forms of life based on chemistry. But what if there's other forms of life based on, for example, electricity? For example, maybe there's some extremely weird life at the center of stars that uses electromagnetism. Kind of like a naturally-occurring digital life.

And another thing: All of the discussion thus far has been on the scale of molecules. But who's to say that life couldn't exist on some unimaginably larger scale, both in space and time? For example, a network of billions of galaxies very subtly interacting over the course of (10^50)'s of years? No, I have no idea what I'm talking about. Someone please flesh this idea out for me, it sounds interesting.

I guess the moral of this post is: What exactly qualifies as 'life' anyway? Perhaps I've gone a bit too philosophical on an otherwise chemistry-based thread. Sorry about that!

[helaeon]

I don't want to sound bad (because you've made some great statements that have cleared things a lot; thank you for putting a cork into the mouths of people who like to troll on threads like this), but as someone supposedly with a biochemistry degree, you don't seem to understand the basics of geology which are heavily immersed into inorganic chemistry, and you should. You need to know these things.

Chlorine can not form atmospheres. Period.

The University I went to the biochem route went :

Year 1: General Chemistry & Basic Lab, Basic Bio if you didn't have it in high school

Year 2: Organic Chemistry & Lab, Cell & Molecular Biology.

Year 3: Physical Chemistry, Microbiology, Instrumental Analysis.

Year 4: Biochemistry, Biochem Lab

I had very little inorganic chemistry only what was in general chem freshman year, high school chemistry. Physical chemistry was more the physics of chemistry. Particle physics and the physical properties of the electron mostly. There was a bunch of physics and calculus and stats and computer science and other courses not directly related to chemistry in there as well that I was required to take.

Inorganic chemistry was year 4 for the pure chemistry majors. The only geology I had was in high school. 120 credits were needed for graduation, required degree courses demanded 87 if them university gen-eds required another 24 non-overlapping. There wasn't much room to cram geology in there. If I would have had extra credits and time I probably would have taken more pharmacy and microbiology classes than I did anyway. An utterly complete chemistry undergrad degree would have taken at least 6 years at that university minimum.

Though I will say in my defense: Yes chlorine is removed from the atmosphere through various reactions (I did read your post before mine and know it is VERY reactive) but enough of it and the exposed surfaces that could react with it can't any longer they're totally saturated. The reaction is then reagent limited, in this case by the surrounding environment rather than the chlorine gas itself. Once photosynthesis started on Earth oxygen gas had to react with everything exposed to the atmosphere until it was completely oxidized and the saturation limit of oxygen dissolved in the oceans had also been reached, only then could the gaseous oxygen begin to concentrate. Life did this. Is it probable that enough chlorine would be concentrated on a planet that some life form could push enough of it into an atmosphere and being used much like oxygen is here it completely alters the chemistry of its planet then after that is complete concentrates it to the point that it is ever present? Nope not probable. Impossible? Also no. "Mess up everything like mad men" and completely alter the chemistry of the planet to the point that it becomes utterly dead? Yes because O2 very nearly did that here. Not trolling and maybe my bio-focus is causing me to over look something here that makes chlorine different under this model. Found this on PubMed which follows that same line of thinking : http://www.ncbi.nlm.nih.gov/pubmed/21118026

Hydrochloric acid isn't really a solvent, the water is. The hydrochloric acid is an aqueous solution, so water is the solvent. There is nothing extraordinary about life chemistries in hydrochloric acid, because its still chemistry of water but with a ton of protons around, there's a whole ecosystem in your stomach that lives that way.

This is what I was thinking as I read this thread. I mean, everyone has had some very interesting and informative opinions on different forms of life based on chemistry. But what if there's other forms of life based on, for example, electricity? For example, maybe there's some extremely weird life at the center of stars that uses electromagnetism. Kind of like a naturally-occurring digital life.

Plants kind of live on electricity. The way chlorophyll works to capture a photon to moves an electron around to make sugars is absolutely bonkers. Really you use electricity a lot too, but not wires or AC current like we think of. Electrical potentials (voltage)? Absolutely critical for the functioning of your cells.

Life is generally defined, as taught to me, as something that utilizes or transforms energy in order to grow and reproduce/replicate. Basically it is something with a metabolism. There is a fuzzy line there between chemistry and life though. You study what I did with biochemistry about DNA and proteins, which are clearly not life. Then you get into ribosomes, not life but closer. Next step up is a cell, well that's life clearly. So where was the line between a very important cellular part that is essential to life on Earth as we know it and a living cell? Where does that put viruses? There's a very strong debate going on right now on that topic. It's probably that the whole is greater than the sum of its parts as far as a cell goes.

Edited June 29, 2014 by helaeon

[Creature]

Having a BsC in biotechnology (essentially biochemistry with a different focus) and about to start my master's thesis this fall I just have to comment on this. I see zero relevance of studying geology when it comes to biochem as a major. Inorganic chemistry is something you need to know the basics of so that when you collaborate with the chemists you know what they talk about and can study whatever you need to on your own. We don't even need that much organic chemistry honestly, at least our work on biotech starts on the macromolecule level with DNA and proteins. You obviously need to know about stuff that's relevant to what you're working with at the moment, but we're not chemists.

As for the topic itself, first thing you need is a molecule able to carry information. This is something you could come up with silicon easily. Essentially just like DNA is structurally a fairly simple molecule and we can construct all kinds of alternatives to DNA by replacing the backbone or using different base pairs, similarly we could device all kinds of structures that hold at least a limited amount of information with arbitrary coding mechanism using a different chemistry. But then you need another type of molecules to decode, encode and replicate this information. And this is something where all the actual science about non-carbon based life essentially ends. You'd need something that's functionally about as complex as a protein but we don't have enough computing power or smart enough algorithms to even begin constructing a model for it.

But in theory if you have the information carrier and the replicator system, then you'd be closer to being able to call it life. I haven't heard of any proposals of inorganic protein-like molecules but in theory you might be able to construct some kind of nanoparticles with complex functions. If someone's encoutered something more substantial then "silicon is versatile" then it would bring something to discuss about to the table. But jumping from a "versatile atom" to life is a pretty huge leap.

Unless we go in the realm of self-replicating robots and stuff like that where obviously we could build a robot that's able to build other robots. But it's not something that can develop on it's own.

[lajoswinkler]

Here's an entirely different idea. What about vanadium-based life? It's a versatile metal capable of forming all kinds of oxides and complex structures. Life based on it would exist in a much hotter climate.

Most transition metals are like that.

The fact is that vanadium is not an abundant element, and carbon is everywhere. Even if we count in the possibility of some kind of life around vanadium as its base (just for the sake of argument; vanadium can't form structures like carbon), the fact is that carbon will do it sooner just because it's vastly more abundant.

In simple terms, the chances of life happening with carbon are enormous because of its atomic structure and abundance.

Transition metals have their share in life. Their atoms are often complexed inside huge carbon molecules and act as crucial components for electron transfer.

This is what I was thinking as I read this thread. I mean, everyone has had some very interesting and informative opinions on different forms of life based on chemistry. But what if there's other forms of life based on, for example, electricity? For example, maybe there's some extremely weird life at the center of stars that uses electromagnetism. Kind of like a naturally-occurring digital life.

And another thing: All of the discussion thus far has been on the scale of molecules. But who's to say that life couldn't exist on some unimaginably larger scale, both in space and time? For example, a network of billions of galaxies very subtly interacting over the course of (10^50)'s of years? No, I have no idea what I'm talking about. Someone please flesh this idea out for me, it sounds interesting.

I guess the moral of this post is: What exactly qualifies as 'life' anyway? Perhaps I've gone a bit too philosophical on an otherwise chemistry-based thread. Sorry about that!

Maybe there's an alien civilization that has turned completely to synthetic mechanisms, or maybe they exist as software in some mainframe. Maybe their existence is carried by electrons, photons or some other particle.

However, life itself will not emerge in the form of naturally occuring digital life because that's not how chemistry works. That would violate the most basic laws of particle behaviour. This is not a problem of life. It has an issue with physics and physical chemistry.

Life requires metabolism with an open thermodynamical system, meaning it needs a border between its interior and environment. The border ensures that the interior can be different from the environment in the means of entropy and energy. All that billions of galaxies could do is to fly around in clusters, passing one through another, and by the time few "stirrs" happen, their stars are exhausted. That's chaos comparable with stirring soup with oil blobs on its surface.

But you're thinking, and that's a good thing. Most people never even thought about these things.

[lajoswinkler]

The University I went to the biochem route went :

Year 1: General Chemistry & Basic Lab, Basic Bio if you didn't have it in high school

Year 2: Organic Chemistry & Lab, Cell & Molecular Biology.

Year 3: Physical Chemistry, Microbiology, Instrumental Analysis.

Year 4: Biochemistry, Biochem Lab

I had very little inorganic chemistry only what was in general chem freshman year, high school chemistry. Physical chemistry was more the physics of chemistry. Particle physics and the physical properties of the electron mostly. There was a bunch of physics and calculus and stats and computer science and other courses not directly related to chemistry in there as well that I was required to take.

Inorganic chemistry was year 4 for the pure chemistry majors. The only geology I had was in high school. 120 credits were needed for graduation, required degree courses demanded 87 if them university gen-eds required another 24 non-overlapping. There wasn't much room to cram geology in there. If I would have had extra credits and time I probably would have taken more pharmacy and microbiology classes than I did anyway. An utterly complete chemistry undergrad degree would have taken at least 6 years at that university minimum.

Though I will say in my defense: Yes chlorine is removed from the atmosphere through various reactions (I did read your post before mine and know it is VERY reactive) but enough of it and the exposed surfaces that could react with it can't any longer they're totally saturated. The reaction is then reagent limited, in this case by the surrounding environment rather than the chlorine gas itself. Once photosynthesis started on Earth oxygen gas had to react with everything exposed to the atmosphere until it was completely oxidized and the saturation limit of oxygen dissolved in the oceans had also been reached, only then could the gaseous oxygen begin to concentrate. Life did this. Is it probable that enough chlorine would be concentrated on a planet that some life form could push enough of it into an atmosphere and being used much like oxygen is here it completely alters the chemistry of its planet then after that is complete concentrates it to the point that it is ever present? Nope not probable. Impossible? Also no. "Mess up everything like mad men" and completely alter the chemistry of the planet to the point that it becomes utterly dead? Yes because O2 very nearly did that here. Not trolling and maybe my bio-focus is causing me to over look something here that makes chlorine different under this model. Found this on PubMed which follows that same line of thinking : http://www.ncbi.nlm.nih.gov/pubmed/21118026

I didn't really try to attack your education. There's no need for sharing private information online.

Regarding chlorine, I can imagine a life that continually releases small amounts of chlorine, so that there are ephemeral traces of it around those populations. For example, a "forest" of such organisms could smell like bleach. But that's reaaaaally stretching it. The whole concept is truly ephemeral not only in the geological timespans, but in much shorter spans, too. I don't see such system as sustainable as what we have with oxygen.

The planet would need to have zero tectonics in order to avoid exposing fresh, reactive surface. However, the stuff planets are made from is such that when chlorine attacks it, soluble compounds are formed. That's why most of Earth's litosphere's chlorine is in the sea in the form of chloride anions. Chlorine emerged in the form of hydrogen chloride from volcanos and it reacted with the stuff around it, being washed into the sea. Oxides and carbonates are poorly soluble.

Chloride landscape would require no solvent rain. It would need to be a desert.

What would be the solvent? Water is oxidized by chlorine.

It would take a tremendous amount of biochemical energy to oxidize chlorine. If the tectonics are dead, the only other source is the star. The planet needs to be close or the star would have to be very luminous. But, as tectonics are dead, solar wind would quickly destroy any complex molecule on the surface.

You see how stuff gets increasingly complicated and we're required to close our eyes "for the sake of argument" in order to make more and more ludicrous concepts? That's where Occam's razor steps in and says carbon and water.

It's already a huge task to start a life. The chances of it happening are very slim, so complicating it even more doesn't yield a valid concept.

Life is generally defined, as taught to me, as something that utilizes or transforms energy in order to grow and reproduce/replicate. Basically it is something with a metabolism. There is a fuzzy line there between chemistry and life though. You study what I did with biochemistry about DNA and proteins, which are clearly not life. Then you get into ribosomes, not life but closer. Next step up is a cell, well that's life clearly. So where was the line between a very important cellular part that is essential to life on Earth as we know it and a living cell? Where does that put viruses? There's a very strong debate going on right now on that topic. It's probably that the whole is greater than the sum of its parts as far as a cell goes.

As you've said, it's a fuzzy line. It deals with emergent phenomena. Viruses are "errors" in DNA that somehow managed to get out of the cell. Lifelike molecular complexes, that's the best way to describe them.

[Aethon]

Wow good thread guys. Bookmarked. Wish I knew more chemistry/geology.

[phoenix_ca]

Defining what life is is as much a philosophical question as it is a purely scientific one. Every time I contemplate it I eventually just get thrown back to Descartes' "Cogito ergo sum" (I think, therefore I am). At least for sentient life. Other forms of life gets fuzzy and confusing as all hell and really depends more on where you draw the line, and wherever you draw it, it's going to be pretty arbitrary.

[lajoswinkler]

Defining what life is is as much a philosophical question as it is a purely scientific one. Every time I contemplate it I eventually just get thrown back to Descartes' "Cogito ergo sum" (I think, therefore I am). At least for sentient life. Other forms of life gets fuzzy and confusing as all hell and really depends more on where you draw the line, and wherever you draw it, it's going to be pretty arbitrary.

That's why line drawing has been abandoned decages ago.

[Idobox]

his is what I was thinking as I read this thread. I mean, everyone has had some very interesting and informative opinions on different forms of life based on chemistry. But what if there's other forms of life based on, for example, electricity? For example, maybe there's some extremely weird life at the center of stars that uses electromagnetism. Kind of like a naturally-occurring digital life.

And another thing: All of the discussion thus far has been on the scale of molecules. But who's to say that life couldn't exist on some unimaginably larger scale, both in space and time? For example, a network of billions of galaxies very subtly interacting over the course of (10^50)'s of years? No, I have no idea what I'm talking about. Someone please flesh this idea out for me, it sounds interesting.

I guess the moral of this post is: What exactly qualifies as 'life' anyway? Perhaps I've gone a bit too philosophical on an otherwise chemistry-based thread. Sorry about that!

I remember reading, a long time ago and in a pretty crappy pop science magazine, that dust in space can form relatively complex structures, especially helices, through tiny gravitational and electromagnetic interactions.

Similarly, plasma are very complex and interact with themselves.

Finally, I've heard time and again, but mostly in SciFi, people talking about strange states of matter, like on the surface of neutron stars, that can form complex structures.

Now it would extremely far fetched to say a form of life could arise on these substrates, but I don't know enough to dismiss it either.

On the subject of digital/artificial life. I don't see any way for it to emerge spontaneously, but self replicating machines built mostly out of silicon and aluminium are completely within the realm of possible, and if the things can evolve, they would be pretty difficult to distinguish from life (especially if not initially built by humans).

If you take Schrödinger's definition of life ( a system that decreases its own entropy by using an energy gradient), a lot of stuff not made of carbon, or even matter, is alive. Like companies, cities, certain computers, memes (in Dawkin's sense, not image macros)...

[Dreadthrone]

Mercury could be a potential habitat for silicon-based life. It is 70% metallic and 30% silicate. It has no gaseous atmosphere. Instead it has a thin exosphere of a variety of elements, including silicon, hydrogen, oxygen, calcium, and many others. This would prevent silicon from forming too many bonds with oxygen.

As for silicon having low versatility, the intense heat and radiation from the sun might excite the electrons enough to enhance its versatility. Covalent bonds might be easier to form in this situation.

The life itself would most likely be photosynthetic, and would rely on nutrients like calcium, sodium, potassium, magnesium, oxygen, hydroxide, iron, and, of course, silicon. It would probably have a silicate or iron-oxide exoskeleton and inner cells of silicon, iron, oxygen, and maybe calcium. Instead of blood, it would have magnetic pathways and gradients for transporting nutrients and waste.

I am not an expert in any way but....all life that we ever know existed ever got water from one source or another in theory it is kinda possible and it could get water from combining o2 and hydrogen. And that would be complex as something insane and it would have to form on land ( making it even harder) AND why would it need an exoskeleton? iron is pretty hard stuff and silicon is decent ( probably stronger then flesh) and i don't think the weapons would be much stronger without going unrealistic mode... for example try making a beautiful drawing without using pre-mixed colors... or even ink to draw with! you would be left with a blank sheet of paper ( maybe red if you got so angry you cut yourself...) and there is very little sunlight there. oh and it takes 59 earth days to rotate... and considering the highly insane quantity of energy it would take to migrate all the way around the world try walking around the world without eating and try supporting a brain with THAT little energy.

i think a creature made of silicon on mercury would have:

some kind of heat storage ( for fifty nine days) or could just try to use the heat from the planet

hopefully some kind of hibernation ( especially if it has a brain)

wings maybe ( yes mercury does not have much atmosphere but it does not have that much gravity ether so it could balance out) plus could be used as giant leaves for photosynthesis.

some way to survive the psycho madman heat

some way to make it less complicated

basically i think it lingers waaay to far to the sifi world simply due to the insane complexity. so basically it would make an epic super cool pet ( you wouldn't have to pay for food ether) but the only way i could see this being done was if somebody decided that they had enough of this bs and wanted a silicon dyno pet and somehow took silicon put it in a mostly water filled vat and made it into a creature then hated it and put it on mercury.

I wish I could have it as a pet though;.;

Edited June 30, 2014 by Dreadthrone