No, I don't mean big green guys with big black eyes 
I'm interested to hear opinions (or facts) on whether or not (you think) there are organisms in our universe that are not carbon-based or made up of elements that make up Earthly organisms.
It just seems to me that if there were life somewhere else in our universe (which is very likely) that, in order for it to form and survive, it would have to adapt to the specific planet/environment. But I don't think there is a planet with a ton of similarities to Earth...so the environment would be very different. For an organism to form and adapt to this different environment is it likely that these forms of life would hardly be similar to that on Earth (in terms of elemental and chemical make up and all that jazz)?
I think if we look solely for life that is very similar to that on Earth and we assume that any possible life out there is very Earth-like, then we'll completely overlook it (if it exists obviously). I think the universe is too big for there not to be anyone else but us
The basic problem is - how do you look?
Optical methods are useful to a point - we can detect earth-like planets by looking for periodic dimming of distant suns and then doing some heavy-duty math. Optical methods will not, however, tell you much else - certainly unlikely to be able to spot life (of any sort), unless that life-form happens to direct a coherent beam of light (such as a laser) in our direction.
That leaves radio-waves. You then have to make assumptions. Would intelligent life naturally develop radio-broadcast technologies like ours (radio, tv etc)? Would a telepathic race develop radio?
So there are inherrent assumptions in the way we look.
There is then the biological issue. Long chain carbon molecules are the only type we know about that are capable of 'developing' the ability to self-replicate (necessary for life). Some people speculate that you could base life on silicon but I find that proposition unlikely - I can't see how long-chain molecules based on silicon could arise. Carbon is the only elements we know about that can do this..
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980221b.html 
Just reading through some things: http://en.wikipedia.org/wiki/Alternative_biochemistry
| Quote: |
| Nitrogen and phosphorus also offer possibilities as the basis for biochemical molecules. Like carbon, phosphorus can form long chain molecules on its own, which would potentially allow it to form complex macromolecules if it were not so reactive. However, in combination with nitrogen, it can form much more stable covalent bonds and create a wide range of molecules, including rings. |
| Quote: |
Arsenic, which is chemically similar to phosphorus, while poisonous for most Earth life, is incorporated into the biochemistry of some organisms.[4] Some marine algae incorporate arsenic into complex organic molecules such as arsenosugars and arsenobetaines. Fungi and bacteria can produce volatile methylated arsenic compounds. Both arsenate reduction and arsenite oxidation have been observed in microbes.[5] Additionally, some prokaryotes can use arsenate as a terminal electron acceptor during anaerobic growth and some can utilize arsenite as an electron donor to generate energy.
Chlorine is sometimes proposed as a biological alternative to oxygen, either in carbon-based biologies or hypothetical non-carbon-based ones. But chlorine is much less abundant than oxygen in the universe, and so planets with a sufficiently chlorine-rich atmosphere are likely to be rare, if they exist at all. Chlorine will instead likely be bound up in the form of salts and other inert compounds.
Sulfur is also able to form long-chain molecules, but suffers from the same high reactivity problems that phosphorus and silanes do. The biological use of sulfur as an alternative to carbon is purely theoretical. However, the biological use of sulfur as an alternative to oxygen is widespread -- strains of sulfur-reducing bacteria have been discovered in exotic locations on earth, and also not so exotic locations, such as aging water systems.[6] These bacteria can utilize elemental sulfur instead of oxygen, reducing sulfur to hydrogen sulfide. Examples of this type of metabolism are green sulfur bacteria and purple sulfur bacteria. Examples of micro-organisms that metabolize elemental sulfur can be traced back 3.5 billion years on Earth.[7] |
Just thought it was some interesting information Obviously, these elements have their pros and cons in this discussion, but felt like throwing it out there just for the sake of knowledge.I think it would be arrogant of us to assume that this planet is the only 1 in the entire universe that supports life. The numbers game suggests there could be billions upon billions of potentially life-supporting planets. What possible reason could htere be for Earth being the only 1 on which life has started.
As for whether alien life-forms could be based on something other than carbon - I'm no biochemist so I'm in no position to answer that. I do think, though, that first contact with an alien life-form will be through robots (either ours or theirs), not living organisms, if their lifespan is less than a few thousand of our years. Interstellar travel would take too long for any lifeforms with a lifespan similar to, or even 2-3 times as long as, our own.
Unless the aliens are made of much srurdier stuff than humans, or most Earth-based lifeforms, robotic craft would be able to withstand much higher G forces, hence much greater acceleration/deceleration and shorter travelluing times. Even so, it could take hundreds of years to travel to even the nearest star with an identifiably life-supporting environment.
I suppose one could argue that what we consider life-supporting may not apply to aliens whose body chemistry is so very different from our own. But unbless we find some evidence, or at least a good theory, of alternative chemistry for life, we have to make assumptions. Currently, our best assumption is that there are certain preconditions for life to exist.
Then there is also the problem of whether we would recognise an alien lifeform as actually being a lifeform. Having seen some of the villagers where I live, I think that's doubtful! 
| DoctorBeaver wrote: |
I do think, though, that first contact with an alien life-form will be through robots (either ours or theirs), not living organisms, if their lifespan is less than a few thousand of our years. Interstellar travel would take too long for any lifeforms with a lifespan similar to, or even 2-3 times as long as, our own.
|
Robots are indeed more likely, but there is the possibility of a generation ship. Just because an individual's lifespan would be too short doesn't mean that they wouldn't find any reason to launch a craft big enough to house a self-sufficient community. Something say, the size of Miami. (We can, of course, assume they have the technology to build, launch, and fly something that big.) The people who took off in it would never get there, but their descendants would. Depending on their culture, that may be more acceptable to them than it would be to us.
As for life forms not based on carbon? Why not? I suspect the only reason we can't think of a way for it to work is that we have no examples. With one non-carbon example, we could probably figure out others. At any rate, it would very difficult to prove that it is not possible for such a thing to exist. | liljp617 wrote: |
No, I don't mean big green guys with big black eyes
I'm interested to hear opinions (or facts) on whether or not (you think) there are organisms in our universe that are not carbon-based or made up of elements that make up Earthly organisms.
It just seems to me that if there were life somewhere else in our universe (which is very likely) that, in order for it to form and survive, it would have to adapt to the specific planet/environment. But I don't think there is a planet with a ton of similarities to Earth...so the environment would be very different. For an organism to form and adapt to this different environment is it likely that these forms of life would hardly be similar to that on Earth (in terms of elemental and chemical make up and all that jazz)?
I think if we look solely for life that is very similar to that on Earth and we assume that any possible life out there is very Earth-like, then we'll completely overlook it (if it exists obviously). |
Considering the countless number of galaxies and the countless number of stars, and the number of planets orbiting each star, there is bound to be another planet with life in the universe. Whether intelligent life exists or not is hard to figure out, but I have a feeling that the laws of physics and the sheer vastness of space simply keep any intelligent life forms from contacting eachother. Any really developed life forms would probably be on the outer edge of the universe, because matter there is presumably the oldest. Millions of light years away, I don't think they'd really be able to see us even with their most powerful technologies --- they'd have an entire, distant, small galaxy of stars to sift through to find planets.
It is obvious that Earth-like planets would be able to harbor life, but it is possible that microorganisms could live in a Venusian-style or Martian-style planet, as well as some of the conditions of the moons orbiting the gas giants, of which Jupiter was theorised to have some sort of low level life form.
Life can exist in extreme locations, some of them the last place you would think. It's concievable that there is life that is made up of other chemicals than carbon, but carbon is just such a good, versitile and bonding material that I don't really think any life form could match up to a carbon based one in complexity with the exception of a silicon-based one .Think of earth as a large mass made up of sand, water, stone etc. It is just here because of the gravitational force. Life is here....
Think of universe, large and never ending... millions of starts, numerous planets...
There are every chances that some where in the universe, one planet will have the same conditions for life...
And I expect, life will be some where else also.
=/ We see people don't even read the opening post...
This really has nothing to do with whether or not there is life somewhere else in the universe. That's basically a given when you look at the probability...
Read the opening post please.
i definitely feel that the are some other life forms in the universe or some others.How can anyone think that we are the only living beings in the vast and ever expanding universe??
I agree with the assessment that any life we find on another planet will probably not be a carbon-based life form. There is so much we don't even know about our own biologies that it would be foolish to assume our form of life is the only one. We often get drawn into our own little circle of thinking others are just like us; we can see it simply at looking at other cultures; we are very ethnocentric or culturally centric and many differences between our own is frowned. This is the reason why we are entrenched in the carbon-based life form view. It is only naturally to extend our personal centric views as myopic as they may be to alien life forms.
We will be shocked by the first alien life forms we encounter. I wouldn't be surprised if the first life form is hydrogen or helium based as they have a very large abundance in the universe. I don't expect our first findings to be human sized yet. Maybe someday in my lifetime, I'll be proven right or wrong.
I would be surprised if any life exists anywhere that isn't carbon or silicon based. There are reasons that carbon is a good candidate as the backbone of most of the molecules we see in living beings. The ability of carbon orbitals to hybridize and form four covalent bonds, its middle-of-the-road electronegativity, and its stability in macromolecules are all really important characteristics that no other molecules really share. It's hard, for example, to imagine an organism based on nitrogen, due to its reactivity. Oxygen is out, because it can only stably bond to two other elements at once. We'll never see hydrogen or helium based life for the same reasons. Covalent bonds involving hydrogen are not very strong, and hydrogen can never be the 'backbone' of any molecule because it can only bond to one atom at a time. Helium is completely inert. I think that other life forms, even if they look totally different to us, are going to have very familiar fundamental chemistries.
For me the massive sulphide deposits near the "black smokers" undersea hydrothermal vent systems that support sulphur-loving bacteria and bizarre worm and clam species are the clearest example of life forming in "unearthly systems". These undersea vents spew 350 C water into the frigid deep-sea environment and still support and are the point of inception for these primitive life form examples.
Hmm...but this life is still carbon based. I'm with Gagnar on this one - I can't see much chance of finding non-carbon based life. Silicon is a possibility but there are serious problems with that as well.
But the general Q is:
Are there other life forms in the universe?
| chasbeen wrote: |
But the general Q is:
Are there other life forms in the universe? |
Well, no answer is possible (yet). If you want an opinion then - yes. | chasbeen wrote: |
But the general Q is:
Are there other life forms in the universe? |
The probability that there isn't other life is incredibly minute....as small as it can get. But that's not the point of the thread.
| Bikerman wrote: |
| Hmm...but this life is still carbon based. I'm with Gagnar on this one - I can't see much chance of finding non-carbon based life. Silicon is a possibility but there are serious problems with that as well. |
I like to leave the window open since we often discover things that go against specific foundations of our science.
I made the discussion mostly because I was talking to someone on this topic and he basically said there was absolutely zero chance non-carbon based organisms could exist. Not that I'm saying they do, but the possibility is there. We know little about the universe (in my opinion). Perhaps there are even elements on Earth we don't know about or that are nonexistent on Earth, but can be found on another planet somewhere in the universe? And these elements support life.
I think the possibility is there. The likelihood, maybe not. But I think we have a very strong bias toward carbon (rightfully so) that could get in our way.I do believe there is other life out there besides us. We don't know everything about outerspace even though we do know a whole lot already. What we know is that there must be certain conditions on a planet for life to exist and there are other planets that we found with running water and oxygen which are necessary for life to exist and a lot of people don't believe it. It may be possible that life exists on other planets out there but I'm sure that we currently don't have the technology to prove it right now, but I'm sure that some day we will have the technology to find out if there are really other life forms out there in the universe. the life forms may look similair to us or may look completely different depending on what they are living off of, just depends on how those organisms adapt to their society just like we adapt to oxygen and our life. It's really interesting to think about and I really wish sometimes that I knew or had the chance to find out what else is out there.
| liljp617 wrote: |
| I made the discussion mostly because I was talking to someone on this topic and he basically said there was absolutely zero chance non-carbon based organisms could exist. Not that I'm saying they do, but the possibility is there. We know little about the universe (in my opinion). Perhaps there are even elements on Earth we don't know about or that are nonexistent on Earth, but can be found on another planet somewhere in the universe? And these elements support life. |
Well, our understanding of basic chemistry and physics is pretty good. I don't think there is much chance of new elements (other than the predicted heavy elements which exist for very short times). It is, as you say, always a possibility, but once we start down that path then we can say that anything is possible, no matter how unlikely. We need to work on plausible scenarios - basing theory on microscopically remote possibilities is not a sensible way to proceed. I'm not suggesting that non-carbon lifeforms are impossible - I'm simply saying that the possibility is so remote that we should concentrate our efforts on looking for carbon-based lifeforms.New substances are always likely to be found, but the only elements that remain to be discovered are the big heavy ones that last microseconds - however we may one day find a stable really large element that has many of the properties of carbon - not convinced though. Carbo is justso good at it, why would life struggle with something else? As far as I'm aware Carbon is relatively abundant throughout the universe (not so much as Hydrogen but its out for the reasons Gagnar posted) so why would life try and adapt something else?
Indeed.
wiki has the following for abundance of elements in the universe (obervable);
Element.................Parts per million
Hydrogen....................739,000
Helium.........................240,000
Oxygen.........................10,700
Carbon...........................4,600
Neon..............................1,340
Iron................................1,090
Nitrogen............................950
Silicon................................650
Magnesium........................580
Sulfur................................440
All Others..........................650
There is also an interesting article on carbon below (moderate science knowledge required).
http://www.sciencemag.org/cgi/content/full/282/5397/2204 I think it is more likely to find energy based entities.
Like perhaps a universe of chi energies or souls.
| jwellsy wrote: |
I think it is more likely to find energy based entities.
Like perhaps a universe of chi energies or souls. |
More likely?The Drake Equation is fairly obvious when you look at it but some of the terms are (and will remain so until the equation is proved) just guesses. Nobody knows how many stars have habitable planets, nobody knows the chances of life developing, and certainly nobody can even begin to guess what the chances of an advanced civilizatuion who have radio technology but choose not to use it are!
It's like searching for the Loch Ness Monster - it will never be proved that there never was a mystery creature in the Loch but it is possible to be proved (either by catching or something).
But all of that aside there is no term in the Drake Equation that mentions the biological/chemical makeup of the beings in questions.
David.
Something I had come across on http://space.com about the discovery of fossilized bacteria found in a meteorite.
"Last year, at a conference on Astrobiology held in Denver, Dr Stanislav Zhmur and colleagues from the Russian Academy of Sciences revealed that they had found what looked like fossilized microorganisms in fragments of several meteorites that fell on the rural town of Murchison in South-East Australia in 1969.
Their electron microscope pictures and comments were recently posted on the web pages of "Cosmic Ancestry" -- part of the Panspermia website, devoted to research and conjecture about the spread of life between star systems."
check it out This is a very valid possibility. The world might have started (most probably so) by extra terrestrial impregnation. The meteorites could have carried in the life form the way we are used to and then the entire life might have started.
All these could only be conjectures. What would have exactly happened can be established only if another earth is created! Otherwise, we will not be able to predict it.
I'm not a scientist but I think that life in other part in the universe is highly probably. I mean, why we only require a huge, colosal universe for only Earth life. It doesn't have any sense. Besides, if we cannot say it, it doesn't mean that they can't exist.
