Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: wolram on 10/03/2006 10:10:30
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The possibility of extra terestrial life seems more likely
http://arxiv.org/abs/astro-ph/0603219
Star like our sun is found.
http://www.cnn.com/2006/TECH/space/03/09/cassini.enceladus/
CNN) -- The Cassini space probe has found evidence of geysers erupting from underground pools of liquid water on Saturn's moon Enceladus, scientists announced on Thursday.
A born optomist
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Thanks for this Robin.
It would have been good to post this in the science news articles thread.
Of course, finding a sun similar to ours means that there just may be a possibility of life akin to ours. This does not mean that life can only exist where there are similar circumstances to our own.
I firmly believe that life is a very adaptable thing, and elsewhere, in addition to circumstances similar to our own, there is life which dwells in conditions completely alien to ours. There just has to be
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I agree Neil, when life on earth can exist in such extremes, from
great depths in the ocean around thermal vents, to the frozen wastes,
and bacteria has been found deep in the earth, it would be a very
strange thing if we were the only ones in the u.
A born optomist
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It would have been good to post this in the science news articles thread.
Can it be moved Neil ?
A born optomist
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It can be posted there for viewing and then left here for discussing...just copy and paste the text and credit the source. I can do it for you if you wish, else, just copy and paste away..YAYYY !!
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quote:
Originally posted by neilep
Thanks for this Robin.
It would have been good to post this in the science news articles thread.
Of course, finding a sun similar to ours means that there just may be a possibility of life akin to ours. This does not mean that life can only exist where there are similar circumstances to our own.
I firmly believe that life is a very adaptable thing, and elsewhere, in addition to circumstances similar to our own, there is life which dwells in conditions completely alien to ours. There just has to be
I think it will ultimately boil down to what do you call life?
I am sure that long term sustainable chemical and physical processes can exist in many contexts, the question is when do you call it life?
Whatever it is, if it exists in an environment very different to our own, it will be very different to anything we would call life here.
Ofcourse, nothing on any of the extraterrestrial planets in our own solar system suggests anything beyond the possibility of microbial life, and nothing even close to suggesting multicellular life of any kind.
George
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quote:
Originally posted by another_someone
quote:
Originally posted by neilep
Thanks for this Robin.
It would have been good to post this in the science news articles thread.
Of course, finding a sun similar to ours means that there just may be a possibility of life akin to ours. This does not mean that life can only exist where there are similar circumstances to our own.
I firmly believe that life is a very adaptable thing, and elsewhere, in addition to circumstances similar to our own, there is life which dwells in conditions completely alien to ours. There just has to be
I think it will ultimately boil down to what do you call life?
I am sure that long term sustainable chemical and physical processes can exist in many contexts, the question is when do you call it life?
Whatever it is, if it exists in an environment very different to our own, it will be very different to anything we would call life here.
Ofcourse, nothing on any of the extraterrestrial planets in our own solar system suggests anything beyond the possibility of microbial life, and nothing even close to suggesting multicellular life of any kind.
George
I quite agree.
Life is what ever we attribute the definition of life to, but at the same time I can also accept that the possibility of life exists that does not pertain to our definition, so, we may have to redefine our definition as ' new ' life is discovered.
How we determine that what we have discovered is life that exists outside our conventional rules for existence is another thing.....but it would be a great thing to discover that there is indeed life out there in.........another someone !!(pun intended) [:)]
Men are the same as women, just inside out !
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quote:
Originally posted by wolram
I agree Neil, when life on earth can exist in such extremes, from
great depths in the ocean around thermal vents, to the frozen wastes,
and bacteria has been found deep in the earth, it would be a very
strange thing if we were the only ones in the u.
A born optomist
Once life has started then it can evolve to live almost anywhere in one form or another
but of course for that life to be around at the thermal vents it had to have started somewhere and evidence suggests that you could count on one hand the amount of times life has develop independently on earth, which isn’t much when you considering how old the earth is.
Michael
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This paper gives an overveiew of the extreme conditions that life can survive in.
http://www.liebertonline.com/doi/abs/10.1089/153110702762027862
A born optomist
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quote:
Originally posted by ukmicky
Once life has started then it can evolve to live almost anywhere in one form or another
but of course for that life to be around at the thermal vents it had to have started somewhere and evidence suggests that you could count on one hand the amount of times life has develop independently on earth, which isn’t much when you considering how old the earth is.
Not sure that this follows inevitably from what we know.
On this planet, live has learned to tolerate any temperature in which liquid water can exist (generally, from slightly below 273 kelvin, to somewhere around 400, and possibly up to 600, kelvin). Our experience of life does not support the notion that life can survive at 100 kelvin or less, not at 1000 kelvin or more; although both of these extremes are well within what is regularly found in various parts of the cosmos.
Ofcourse, one of the aspects of life, all forms of life, is that they create their own micro-environment, so the limiting factor is not probably what the external environment might be, but how effectively the chemical processes of life can be insulated from that environment. A single celled organism, although its chemistry is simple, so is its defensive isolation, merely a thin cell wall; while a multicellular organism, although its chemistry is more sensitive to its interior environment (warm blooded animals requiring very precise control of temperature), but so is its environmental management and isolation more sophisticated.
The limiting factor is, I suppose, whether the local materials exist to adequately provide for that micro-environmental isolation and management that is sufficient for the external environment in which the organism has to survive.
George
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George your so picky, meticulous, exacting, finicky,difficult to please [:)][:D]
Michael
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Re: Neilep's above post
Yet there is also a theory that nonobacteria began the spread of life across the galaxy, at least. This is not as rediculous as it may seem on the surface. These little "bugs" are considerd a major contributor to artrioschirosis, acording to the Mayo Clinic.
http://www.sciencedaily.com/releases/2004/05/040525060705.htm
So, perhaps we just do not understand life. The oldest know bacteria or bacteria made artifacts are almost as old as the earth itsel.
Just a thought. [^]
If I only had a little humility, I'd be perfect.
----Ted Turner
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quote:
This paper gives an overview of the extreme conditions that life can survive in.
Surviving is one thing, life developing for the first time on a planet devoid of all life is the biggest hurdle to there being extraterrestrial lifeforms. it just doesnt happen every day, the conditions required to give the spark of life to a collection of amino acids etc could be so exacting or so rare that the chances of it happening could be 1 in 100 billion trillion or more.
Michael
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quote:
Originally posted by ukmicky
quote:
This paper gives an overview of the extreme conditions that life can survive in.
Surviving is one thing, life developing for the first time on a planet devoid of all life is the biggest hurdle to there being extraterrestrial lifeforms. it just doesnt happen every day, the conditions required to give the spark of life to a collection of amino acids etc could be so exacting that the chances of it happening could be 1 in 100 billion trillion or more.
Michael
Michael, are you sure those odds are accurate ?....Those are not good odds and virtually isolates that form of life from happening anywhere else !
Men are the same as women, just inside out !
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I'm not exactly the best at calculating odds and it is just a possibility but a possibility which does exist. its hard to put a figure on something when the odds of that something happening anywhere at anytime are so outstandingly high. We could be on the luckiest planet in the luckiest solar system in our our galaxy,a one in a 100 billion chance and are only here due to the most amazing amount of luck.
In reality they don't even know how life started at all, its all guess work, lots of different theories.
However using earth as a model and going by the evidence which has survived they know whatever process it was which was used here on earth its not something that happens very often when you consider the earth is 4.5 billion years old and you could count how many times its happened here on one hand and you would probably have fingers to spare.
quote:
Even on Earth the origin of life is a stubbornly enduring mystery. “How can a collection of chemicals form themselves into a living thing without any interference from outside?” asks Paul Davies, a physicist and writer. “On the face of it, life is an exceedingly unlikely event,” he argues. “There is no known principle of matter that says it has to organize itself into life. I’m very happy to believe in my head that we live in a bio-friendly universe, because in my heart I find that very congenial. But we have not yet discovered the Life Principle.”’
Joel Achenbach, Life Beyond Earth, National Geographic, January 2000, p. 45.
professor Andy Knoll of Harvard university:
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All life that we know of is fundamentally pretty similar. That's why we think that you and I and bacteria and toadstools all had a single common ancestor early on the Earth. If you look at the cell of a bacterium, it has about the same proportions of carbon and oxygen and hydrogen as a human body does. The basic biochemical machinery of a bacterium is, in a broad way at least, similar to the chemistry of our cells.
The origin of life is still a mystery.
Michael
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Michael - I find it inconceivable that the only life in the whole universe is here on Earth. OK, maybe it was a fluke; but when you consider just how many other planets there may be, how different life-forms are on Earth, the diverse environments in which life on Earth thrives, there just has to be somewhere else where it has happened - like Belgium.
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I agree its a hard one to swallow but in theory completely possible.
Also you cant use the diversity of life on earth and the different environments which life thrives here as an argument for life on other planets because the different species and ecosystems which they live in is a result of evolution and have got nothing to do with the conditions required for life to begin in its first instance (lifes origin)
Remember they believe all life on earth is related,They believe all life has the same common ancestor. Which means if they are correct its happened here once in the history of the earth.
Michael
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quote:
Originally posted by ukmicky
Remember they believe all life on earth is related,They believe all life has the same common ancestor. Which means if they are correct its happened here once in the history of the earth.
Michael
This does not follow.
Two siblings are related (they may even be identical twins), but that does not mean that they only had a single parent.
What you might say is that it shows they shared the same common ancestors, but that is not the same as saying that they shared the same common ancestor.
(I know – I'm impossible to please [:D])
George
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We used to think the planets in our own solar system were unique, now we are discovering that planets are common. In fact very common. We always use the number of stars as to represent the size of a galaxy and the numbers are phenomenal. Even more phenomenal now is the potential number of planets…now the number is growing exponentially, and now we must multiply it even further by the number of galaxies out there.
I just cannot accept that life is so rare. I believe that the distant future will be filled with life from all over, we just need to discover it……..And that will come when we are advanced enough to build tools capable of finding it. We are held back by our inabilities.
I suppose there could still be the possibility that despite the age of the Universe that WE are indeed the first forms of life (as we know it) to exist…now what are those odds ?
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It seems quite likely that simple tife forms started quite quickly and possibly life several times on the earth but it took quite a period odf stability to achive things as complicated as a wooodlouse during the cambrian explosion so on the whole I reckon that if the materials are there and the conditions are anything like suitable life will start and multicellular life will follow in a few hundred million years but as for inteeligent communicating life capable of building a spaceship wll thats an entirely different matter.
There's a fair chance that that could be a bit of an oddirty because getting musch beond the hunter gatherer social group is quite a barrier
Learn, create, test and tell
evolution rules in all things
God says so!
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quote:
Originally posted by Soul Surfer
It seems quite likely that simple tife forms started quite quickly and possibly life several times on the earth but it took quite a period odf stability to achive things as complicated as a wooodlouse during the cambrian explosion so on the whole I reckon that if the materials are there and the conditions are anything like suitable life will start and multicellular life will follow in a few hundred million years but as for inteeligent communicating life capable of building a spaceship wll thats an entirely different matter.
There's a fair chance that that could be a bit of an oddirty because getting musch beond the hunter gatherer social group is quite a barrier
Learn, create, test and tell
evolution rules in all things
God says so!
Hi Ian thankyou for the reply
Why is it quite likely that simple life forms started quite quickly and several life forms possibly appeared several times on the earth. (if thats what you mean)
Maybe if they knew what the mechanism for life in the beginning was then maybe there would be some basis to the theory that life started quickly and in many unsuccessful guises but as there is no surviving evidence from the time period it makes me wonder why everybody assumes it. Or am i missing something,it wouldnt be the first time[:)]
Michael
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Given that life appears shortly after the end of the Heavy Bombardment period, it had to start quite quickly. Of course, pan spermia avoids this issue of rapid origin.
Observe; collate; conjecture; analyse; hypothesise; test; validate; theorise. Repeat until complete.
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ophiolite is there any chance of having a person type name for you sir, its so much nicer to talk to someone on a first name basis,much more friendly like [:)] any name will do you can call yourself tom, dick or even harry if you wish.
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I'm OK with the idea that the soup could have come from space,to me whats more interesting is the spark which ignited the soup and whether or not it happened once or lots of times. If life began from the soup once then to me it says its a luck thing and something that wouldn't have necessarily happened all over our galaxy or the universe meaning we could be practically alone in the universe. Understandably its a thought which most people do not wish to or like to entertain, but its an idea which even though i also don't like much i feel i need to investigate further .
Michael
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quote:
Originally posted by neilep
We used to think the planets in our own solar system were unique, now we are discovering that planets are common. In fact very common. We always use the number of stars as to represent the size of a galaxy and the numbers are phenomenal. Even more phenomenal now is the potential number of planets…now the number is growing exponentially, and now we must multiply it even further by the number of galaxies out there.
I just cannot accept that life is so rare. I believe that the distant future will be filled with life from all over, we just need to discover it……..And that will come when we are advanced enough to build tools capable of finding it. We are held back by our inabilities.
I suppose there could still be the possibility that despite the age of the Universe that WE are indeed the first forms of life (as we know it) to exist…now what are those odds ?
We know that there are some rather unusual things about our solar system, and some we know have strongly shaped our life forms, others are less clear what effect they have.
Firstly, we have a significant amount of heavy elements on our planets, without which we could not have a magnetic field, and we could not have a hot core (and hence could not have plate tectonics). In order to have so much heavy material in the planet, as far as I am aware, we needed to have been attached to a star that had been through two super-nova.
Secondly, our position on the edge of the galaxy has meant that we have relatively less cosmic background radiation than many of the stars deeper inside the galaxy.
These two facts alone would disqualify most others stars in the universe from having a similar life history to our own. This does not preclude that life might exist in environs very different to our own, but it does preclude a simple assumption that counting the number of planets in the universe necessarily bears any relationship to counting the number of Earth-like planets in the universe.
The other problem is the fairly narrow window life has for forming. Life on Earth is only about 4 to 5 billion years old, and yet within about another 5 billion years, our galaxy will probably collide with the Andromeda galaxy, and probably extinguish life on this planet. Thus the window of opportunity for life on this planet is probably about 10 billion years.
George
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quote:
Secondly, our position on the edge of the galaxy has meant that we have relatively less cosmic background radiation than many of the stars deeper inside the galaxy.
Is that of any great significance? Life on Earth has evolved with a low level of tolerance to radiation. I think it quite plausible that life could eveolve with a much greater tolerance. Even here on Earth, cockroaches & scorpions (to name but 2) have an incredible high tolerance compared to humans.
If I remember correctly, radiation harms the struture of cells. So what if there are creatures that aren't cell/DNA based? I find it quite an arrogant point of view to assume that we work in the only way possible.
I referred to the diversity of life and environments on Earth merely to show that life can exist in very different conditions. Creatures have been found that live around underwater fumeroles and thrive on SO2. That to me says that just because a planet may have a high concentration of to-us toxic gases, it doesn't preclude life being found there.
As for the spark that caused life to begin being a fluke, that is mere conjecture. It is just as possible that given similar start conditions, life is inevitable.
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quote:
Originally posted by ukmicky
ophiolite is there any chance of having a person type name for you sir, its so much nicer to talk to someone on a first name basis,much more friendly like [:)]
It is not a practice I personally like. I have found it very confusing as a newcomer to this board to find people posting things like "thank you Ian", leaving me wondering exactly who Ian is.
On other boards most people call me Oph, or Ophi. If they don't like me then Awfulite, or Oafy are moderately witty and convey the insult quite well.
Observe; collate; conjecture; analyse; hypothesise; test; validate; theorise. Repeat until complete.
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Raditation harms cells by breaking chemical bonds within molecules. I don't think any element of our understanding of "life" (at least as discussed here) can cope without molecules, so radiation will have an effect on any lifeform.
I think life has to assume self organising systems of molecules and radiation breaking chemical bonds at random will make that more difficult to sustain.
On another note, someone mentioned in another thread the idea of "nanobacteria" personally I think it's a daft name for an entirely non-cellular possible organism (they seem to self replicate), but interesting in the evolutionary sense...
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George,
I am not suggesting that life equitable to our own exists but life in any form. Earth type planets are not prerequisite for life, I firmly believe.
Certainly, being on the edge out here has probably gone a long way to manifest this unique planet. But I was not implying Earth Type planets at all, besides, there may well be life right at the heart of the Galaxy , we just don't know.
I would be satisfied, actually I would be blown away !!..if it was discovered that some bacteria existed elsewhere. The question as to whether we are alone in the Universe would finally be answered.
It's about 25 billion years before we collide with the Andromeda, of course, every star in the sky will be dead and gone by then, replaced by the next generation (or two) of stars.
One things for sure, either we'll discover life elsewhere (or be discovered) or it will be us who deposit life on other worlds.
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quote:
Originally posted by neilep
It's about 25 billion years before we collide with the Andromeda, of course, every star in the sky will be dead and gone by then, replaced by the next generation (or two) of stars.
http://www.haydenplanetarium.org/hp/vo/ava/avapages/G0601andmilwy.html
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Two million light years (20 billion billion kilometers) away lies the Andromeda Galaxy, about the same size and shape as the Milky Way. Current measurements suggest that, in about five billion years, the Milky Way and Andromeda may collide!
http://www.cita.utoronto.ca/~dubinski/tflops/
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The nearest big spiral galaxy to the Milky Way is the Andromeda galaxy. Appearing as a smudge of light to the naked eye in the constellation Andromeda, this galaxy is about twice as big as the Milky Way but very similar in many ways. At the moment, it is about 2.2 million light years away from us but the gap is closing at 500,000 km/hour. While most galaxies are rushing away as the universe expands, Andromeda is the only big spiral galaxy galaxy moving towards the Milky Way. The best explanation is that the two galaxies are in fact a bound pair in orbit around one another. Both galaxies formed close to each other shortly after the Big Bang initially moving apart with the overall expansion of the universe. But since they are bound to one another, they are now falling back back together and one very plausible scenario puts them on a collision course in 3 billion years.
George
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quote:
Originally posted by DoctorBeaver
quote:
Secondly, our position on the edge of the galaxy has meant that we have relatively less cosmic background radiation than many of the stars deeper inside the galaxy.
Is that of any great significance? Life on Earth has evolved with a low level of tolerance to radiation. I think it quite plausible that life could eveolve with a much greater tolerance. Even here on Earth, cockroaches & scorpions (to name but 2) have an incredible high tolerance compared to humans.
If I remember correctly, radiation harms the struture of cells. So what if there are creatures that aren't cell/DNA based? I find it quite an arrogant point of view to assume that we work in the only way possible.
I referred to the diversity of life and environments on Earth merely to show that life can exist in very different conditions. Creatures have been found that live around underwater fumeroles and thrive on SO2. That to me says that just because a planet may have a high concentration of to-us toxic gases, it doesn't preclude life being found there.
As for the spark that caused life to begin being a fluke, that is mere conjecture. It is just as possible that given similar start conditions, life is inevitable.
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quote:
Originally posted by rosy
Raditation harms cells by breaking chemical bonds within molecules. I don't think any element of our understanding of "life" (at least as discussed here) can cope without molecules, so radiation will have an effect on any lifeform.
I think life has to assume self organising systems of molecules and radiation breaking chemical bonds at random will make that more difficult to sustain.
Inevitably it must be of significance, but I did say that that alone would not preclude the possibility of life existing elsewhere, but at very least it must make it very different.
Yes, radiation does damage the molecules within cells, but that is why cells have repair mechanisms, and why different organisms have different levels of stability in their molecular structures.
I would suspect that even on this planet, life probably first developed in a domain that was to some extent isolated from the worst of the radiation (either deep beneath the ocean, or in clay deposits), and adapted to more exposed domains only after it had developed the appropriate mechanisms to repair radiation damage.
But beyond the direct damage to the chemistry of life that radiation might have, what effect will it have on the wider environment? If the radiation levels are too high, could it push up global temperatures too far? Could regular interstellar bodies be hitting the planets and causing too frequent extinction events that might allow some life, but not give it time to develop to anything complex? Could such events even cause excessive erosion of the surface and atmosphere of the planets?
George
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quote:
Originally posted by rosy
Radiation harms cells by breaking chemical bonds within molecules. I don't think any element of our understanding of "life" (at least as discussed here) can cope without molecules, so radiation will have an effect on any life form.
I think life has to assume self organising systems of molecules and radiation breaking chemical bonds at random will make that more difficult to sustain.
Hi rosy There is a lifeform which can completly repair radiation damage to its cells and dna within hours. Halo bacterium.
quote:
Halo bacterium appears to be a master of the complex art of DNA repair. This mastery is what scientists want to learn from: In recent years, a series of experiments by NASA-funded researchers at the University of Maryland has probed the limits of Halo bacterium’s powers of self-repair, using cutting-edge genetic techniques to see exactly what molecular tricks the "master" uses to keep its DNA intact.
"We have completely fragmented their DNA. I mean we have completely destroyed it by bombarding it with [radiation]. And they can reassemble their entire chromosome and put it back into working order within several hours," says Adrienne Kish, member of the research group studying Halo bacterium at the University of Maryland.
Being a virtuoso at repairing damaged DNA makes Halo bacterium one hardy little microbe: in experiments by the Maryland research group, halo bacterium has survived normally-lethal doses of ultraviolet radiation (UV), extreme dryness, and even the vacuum of space.
http://science.nasa.gov/headlines/y2004/10sep_radmicrobe.htm
However halobacterium have not just started out in there quest for life and have evolved their unique ability to repair there cells. I doubt any form of life would be able to evolve on a planet receiving large does of radiation unless they were somehow shielded and their given time to evolve systems for repair.
Michael
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But who says life must be DNA-based? All creatures on Earth are, true; but that is probably because the original living organism (whatever it may have been) was, & we are all descended from it. Who is to say that 1 tiny environmental or chemical difference may have caused a replicatory mechanism other than DNA to have arisen?
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Fair enough George....I wish I could recollect my sources too that say it's 25 billion.......what ever the time period ..........it's a long time and just because a source reports or states it, does not necessarily make it so!!ANYWAY !!..that's beside the point when the discussion is about life elsewhere in the Cosmos.
I think it's very difficult for some people to be able to see 'outside ' because of the nature of what we are, that is, DNA based carbon life forms...and so we humanise our outlook too.....we take our own very special form of life and use it as a template and apply it to everything else too.
I think we need to be able to understand that we should accept the possibility that life may exist elsewhere that could conceivably be so alien to us that we may never be able to detect it. There may well be life that exists that does not follow the usual rules,birth, growth, reproduce etc etc....and also perhaps in different planes of existence, maybe out of phase, perhaps a second to them is a year to us etc etc....I'm not suggesting supernatural at all.....very very natural...for them !...however, I would place bets that within a relatively short space of time, the answer to the question will be answered.
Should non Earth life be found within THIS solar system...on one of those moons, deep down inside the oceans of Callisto or Europa......how would the discovery of life there affect peoples thinking of life elsewhere ?
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But who says life must be DNA-based? All creatures on Earth are, true; but that is probably because the original living organism (whatever it may have been) was, & we are all descended from it. Who is to say that 1 tiny environmental or chemical difference may have caused a replicatory mechanism other than DNA to have arisen?
True but i feel we should only use our time and money to examine what we have evidence of and to put time and effort in to other possible forms of existence without any evidence of,would hamper are research into things that we know are real. And wouldn't any other form of surviving life still have to use the same basic mechanisms which DNA uses for evolution to work. There could be major differences but wouldn't there have to be also major similarities.
Michael
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Michael - I have to disagree. That could very well be the reason why we DON'T discover life elsewhere. I'm with Neil on this 1. Life elsewhere could be so different from that on Earth that if we restrict our search to only looking for something that is familiar to us, we could miss it completely.
I also agree with Neil about timescales. I remember seeing a film, or it may have been a TV program like Star Trek - I can't remember now - about an alien race who lived their lives in what, to humans, would be the blink of an eye. Transmissions from their planet were practically undetectable as they happened so fast. If their entire life lasted only 1 second, imagine how short the duration of any messages would be. I'm not putting that forward as a strong possibility, by the way; but what if an advanced civilisation had developed a technique for condensing and transmitting data so fast that they could send the entire Britannica in a nanosecond? We wouldn't have a hope in hell of detecting it.
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While I do accept that we must prioritise funding, and it is logical to put the greater funds where there is more demonstrable likelihood of success, but I do agree with Eth, if we don't look we won't find, so we have to allocate some monies to blue skies research.
With regard to life being so fast that we can't detect it – the greater likelihood may be the converse, since red shifts should have the effect of slowing down what we see.
As for the notion that life may be something unlike anything we expect, there is a slight paradox here. Certainly, whatever we discover may be totally unlike anything we expect to find, but on the other hand, it can only be life if it fits in with whatever our definition of life is, and thus must in some way conform to our expectations to some degree, or else we would not even recognise it as life.
George
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Basically what i was saying is yes look for ET but only in places which are earth like, because we have no evidence that life could exist in any other form other than what we see on earth. But even if we do somehow find signs of life in some far flung solar system how would it help us, is it worth spending billions just so we can say yes.
Michael
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quote:
Originally posted by ukmicky
Basically what i was saying is yes look for ET but only in places which are earth like, because we have no evidence that life could exist in any other form other than what we see on earth. But even if we do somehow find signs of life in some far flung solar system how would it help us, is it worth spending billions just so we can say yes.
Michael
What are we exploring distant space for (near space may have direct relevance, but does it matter what is 200 light years away?).
Once we understand why it matters if there is a black hole 200 light years away, we might also be able to answer why it matters if there is life 200 light years away.
In a sense, it might be argued that if we found life on something that was very unearthlike, it would actually tell us more that if we just find life that is a carbon copy (sorry about the pun) of ourselves.
The second point is, what actually are we looking for when we say we are looking for life? Would we know what it was if we saw it? Do we even really know what life is on this planet, let alone trying to understand what it is on another planet (or even off another planet)?
George
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quote:
As for the notion that life may be something unlike anything we expect, there is a slight paradox here. Certainly, whatever we discover may be totally unlike anything we expect to find, but on the other hand, it can only be life if it fits in with whatever our definition of life is, and thus must in some way conform to our expectations to some degree, or else we would not even recognise it as life.
All that would mean is that our definition is incorrect.
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quote:
Originally posted by DoctorBeaver
quote:
As for the notion that life may be something unlike anything we expect, there is a slight paradox here. Certainly, whatever we discover may be totally unlike anything we expect to find, but on the other hand, it can only be life if it fits in with whatever our definition of life is, and thus must in some way conform to our expectations to some degree, or else we would not even recognise it as life.
All that would mean is that our definition is incorrect.
Incorrect? How can a definition be incorrect – it is whatever we choose it to be. We may choose to change a definition, but that does not make either the new or the old definition incorrect per se.
A definition may be considered incorrect if the definition we are using does not agree with the commonly definition of the word, but that is a relative incorrectness (i.e. a lack of agreement) but not an absolute incorrectness.
On the other hand, if everyone agrees with a certain definition of life (I am not saying this is the case), and what we find is not consistent with that definition, then it is not life.
Certainly, it is possible (in fact, one might even argue the converse to be impossible) that a definition might contain inconsistencies, where what we find agrees with some parts of the definition but not other parts of the definition. This doesn't make the definition wrong, merely internally inconsistent,
George
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In my view life, must mean, (some thing) able to reproduce and evolve, inteligent life is quite
different, how do (we) define intelligent, on another world some thing akin to a tree stump could be pondering if humans are alive.
A born optomist
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quote:
Incorrect? How can a definition be incorrect – it is whatever we choose it to be. We may choose to change a definition, but that does not make either the new or the old definition incorrect per se.
A definition can be incorrect if it is based on incomplete knowledge. Someone in rural England in the middle ages may have defined a human being as looking very much like himself. He would quite probably have included his own skin colour. His definition would therefore have been based on an incorrect assumption; i.e. that all humans are the same colour.
Definitions must change if an increase in pertinent knowledge shows them to be wrong.
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Originally posted by DoctorBeaver
A definition can be incorrect if it is based on incomplete knowledge. Someone in rural England in the middle ages may have defined a human being as looking very much like himself. He would quite probably have included his own skin colour. His definition would therefore have been based on an incorrect assumption; i.e. that all humans are the same colour.
Definitions must change if an increase in pertinent knowledge shows them to be wrong.
Ignoring the fact that people of different skin colour have been in Europe, and Europeans have been around the perimeter of North Africa, for some considerable time; but more pertinently, if the definition of 'human' excluded blacks, then that was the correct definition for them (just as their definition of 'girl' might be gender neutral, while ours excludes young males – which is the right definition, and which is the wrong definition).
This can lead to some anomalies, as we still retain phrases and written documents from past eras that assume a definition of the words used at the time the phrase of document was first created, but the definition of the words has changed, giving and incorrect modern interpretation of the phrase or document.
Ofcourse, definitions are created to support the contemporary knowledge base, and as knowledge changes, so does the meaning of words. On another thread, we are discussing viruses, and assume some knowledge of what a virus is, but that knowledge is very different to the knowledge that someone in ancient Rome would have known about disease, and thus we have interpreted the word virus to have a meaning totally alien to the meaning the ancient Romans would have used it for. Does this mean that there definition for the word virus was incorrect?
George
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Ofcourse, definitions are created to support the contemporary knowledge base, and as knowledge changes, so does the meaning of words. On another thread, we are discussing viruses, and assume some knowledge of what a virus is, but that knowledge is very different to the knowledge that someone in ancient Rome would have known about disease, and thus we have interpreted the word virus to have a meaning totally alien to the meaning the ancient Romans would have used it for. Does this mean that there definition for the word virus was incorrect?
I'm not sure what "virus" was supposed to mean to a Roman so I can't really comment on that. It's quite possible that the word was adopted for what we now call a virus because a word was needed whose existing definition meant something similar. Taking an existing word and applying it to something new does not change its original definition. Take the word "gay". It still means "happy" as well as "homosexual"; its original definition has not changed, another definition has been added.
I think that is a very different thing to sticking rigidly to a definition when contemporary knowledge shows that definition to be incomplete or incorrect.
Brand new forum
http://beaverland.forumup.us/
More than just science
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Originally posted by DoctorBeaver
I'm not sure what "virus" was supposed to mean to a Roman so I can't really comment on that. It's quite possible that the word was adopted for what we now call a virus because a word was needed whose existing definition meant something similar. Taking an existing word and applying it to something new does not change its original definition. Take the word "gay". It still means "happy" as well as "homosexual"; its original definition has not changed, another definition has been added.
I think that is a very different thing to sticking rigidly to a definition when contemporary knowledge shows that definition to be incomplete or incorrect.
Virus was a word the Romans used to refer to a toxic slime.
The point is, to say that our definition of life will ever be proven wrong, not merely superseded by a definition that is more useful to later generations, but no more or less right or wrong that anything we use it for today, we first need a reference point against which we can judge what life should mean, and then later judge that it does not mean that. Would you like to propose a reference point against which we can judge the definition of life?
George
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Originally posted by wolram
In my view life, must mean, (some thing) able to reproduce and evolve, inteligent life is quite
different, how do (we) define intelligent, on another world some thing akin to a tree stump could be pondering if humans are alive.
A born optomist
Sounds reasonable, but does have some problems.
Is a man who has had a vasectomy (or a woman beyond menopause) dead? They are certainly not able to reproduce, or evolve.
A star is able to reproduce (not sure if it can be regarded as evolving or not) – would that make a star a living entity?
Are viruses living? Many biologists do not regard viruses as living because they cannot copy their own DNA, but require another living cell to do the copying for them; nonetheless, they do effectively reproduce, and certainly do evolve.
What about houses – do they reproduce and evolve? Like the virus, they do not themselves have the capacity to replicate, but with the help of other living organisms (namely human beings), they do reproduce and they do evolve. Yes, I know, this example may seem absurd; but if we come across some novel process in some far off place, who is to say what is absurd and what is not?
George
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Fire.
It's birth is a spark. It grows, it spreads, it has offspring and dies, but it's clearly not alive.
But, there may be life out there which resembles fire but has one or two extra ingredients that afford it sentience. Should we discover it then we would have no choice but to deem it alive, despite it not meeting our criteria for our definition of life.
PLEASE, I don't want to turn this into a religious thread, but would religious people consider God alive I wonder ! Ok , they might say that WE are Gods children but what about the other facets of ' life '...anyway..maybe this paragraph is for a different thread.
I think the term 'life' is malleable and may have to be altered with precursors to accommodate life in all its forms and states that do not apply to our current definition.
Men are the same as women, just inside out !
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has one or two extra ingredients that afford it sentience
I think you're setting the bar a bit high here Neil. I wouldn't normally call an amaoeba sentient.
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Originally posted by neilep
Fire.
It's birth is a spark. It grows, it spreads, it has offspring and dies, but it's clearly not alive.
Fire spreads (i.e. it grows), but it does not reproduce (i.e. it does not create distinct and separate replicate units of itself), and for this reason, it cannot be regarded as evolving (i.e. creating offspring that are separate from the parent, that are similar to the parent, but that are nonetheless different to the parent, and where the difference is subject to selective advantage and disadvantage that will cause inheritable changes in future offspring).
Whether stars fall into this category is open to debate (stars certainly do create distinct and separate replicate units of themselves, but do they contain inheritable traits that are subject to selection?), but houses do indeed fall into this category (a change in house design, if successful, can spawn new similar houses to be built).
Previous generations would have considered fire to be alive, but then they did not base life upon the notion of reproduction or evolution, but on being able to respond to the environment around it (fire will be effected by its environment, and so is quick-silver, hence its name).
But, no-one has answered my question, that if life is defined by its ability to reproduce, does the inability of an individual to reproduce mean we have to define that individual as not being alive?
quote:
But, there may be life out there which resembles fire but has one or two extra ingredients that afford it sentience. Should we discover it then we would have no choice but to deem it alive, despite it not meeting our criteria for our definition of life.
I think Rosy has answered the question on sentience.
George
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Yes you're right (Rosy and George.....hmmm..sounds like a kids TV show !!) sentience does not make for life....sorry *bites knuckles and eats humble pie*...that was clearly the wrong thing to say...
...however, I would say fire does make offspring...sparks from it produce new flames and hence offspring.
Someone who can no longer produce children is still clearly alive and therefore does indeed subscribe to perhaps an alternate definition for the word life, be it through a sterilization process or just plain old age.................
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Originally posted by neilep
...however, I would say fire does make offspring...sparks from it produce new flames and hence offspring.
I would question your notion of offspring because I would question the notion of a uniquely identifiable fire (fires can merge as well as split, so one cannot regard as fire as a self contained organism with defined boundaries that would allow one to unambiguously define a parent and a child).
That aside, fir will fail Robin's (wolfram) evolution test – fires have no variable inheritable traits that might be the basis for evolution.
That having been said, evolution is a relatively modern concept, and one has to ask whether it is appropriate to base a definition of life on a presumption of evolution (a notion that some religious groups would I think not accept – although I don't think they would have any problem with the notion of inheritable traits as such).
quote:
Someone who can no longer produce children is still clearly alive and therefore does indeed subscribe to perhaps an alternate definition for the word life, be it through a sterilization process or just plain old age.................
So, do we now have two definitions for life, or will this alternative definition of life suffice on its own, and can we discard the concept of reproduction as a basis of the definition of life?
Would you like to hazard a guess as to what this new definition might be?
That having been said, and a moment of reflection, I don't think the above obstacle is as much of a problem as I originally proposed – we simply have to reverse our definition of life – rather than saying that life is that which is capable of reproduction, we could better say that life is the product of reproduction (now why didn't you think of that – do I need to carry both sides of the argument myself [:D])
Although, even the above redefinition has a problem with how do we exclude corpses from our definition (although, within some limitations, I think there may be ways around that, although those ways might have a problem with defining the exact moment of death).
George
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Someone who can no longer produce children is still clearly alive and therefore does indeed subscribe to perhaps an alternate definition for the word life, be it through a sterilization process or just plain old age.................
May be one can not adjudge an unknown individual as alive, if we can not
communicate with it, it shows no sign of reproduction, and does not
consume food , It would have to be a community of (aliens)
we study, if they did none of the above it would be difficult to
call them alive.
A born optomist
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quote:
Originally posted by wolram
May be one can not adjudge an unknown individual as alive, if we can not
communicate with it, it shows no sign of reproduction, and does not
consume food , It would have to be a community of (aliens)
we study, if they did none of the above it would be difficult to
call them alive.
I agree about whether we are able to judge whether something is alive or not – but that is different from how we define whether something is alive or not. It may well be the case that we cannot determine whether an individual meets that definition without seeing a large number of individuals, but nonetheless, in order to be able to say something is alive, we must be able to say that each and every individual meets the definition of being alive (it's no good simply saying that because 60% of those we see are demonstrably alive, therefore we define – not assume, but define - that they are all alive).
OK, I would put forward the following tests for something to be regarded as living:
a) It must be able to modify its environment in a way that assists its survival (even bacteria can do this).
b) It must be the product of imperfect reproduction. The nature of the imperfections must be themselves inheritable, and relevant to the ability of the organism to survive. This logically leads to a need for a clearly defined parent child relationship (this would exclude fire).
c) Not really a separate matter, since it is a natural consequence of the above conditions, the organism must have clearly defined bounds (you must be able to say throughout the life of the organism that you can state what is a part of the organism and what is not a part of the organism).
d) In order to settle problems with defining the bounds of an organism, particularly with regard to organisms that share the same genetic code (e.g. identical twins or plants grown from cuttings), I would say one should be able to find a way of killing an entire organism by attacking only one part of an organism (if you remove a vital organ from a twin, you will kill the entire individual, but not their twin sibling).
With regard to Niel's question pertaining to God, God is (in the Judeo-Christian-Islamic traditions) perfect, and not the product of reproduction (if one looked at Gods in the classical Greek pantheon, one might see a different picture).
OK, first question – do people have any major problems with the above definitions.
If the above is agreeable, how would you go about testing whether a particular entity met those criteria or not?
George
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Phew George !!..You don't arf give food for thought and force others to use their brain !! (you need a new contract !!)...I'm going to sit back for a while, twiddle my thumbs ** before I accidentally delete this thread also !!
**actually this means I'm going to wait until someone else answers !!
Men are the same as women, just inside out !
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b) It must be the product of imperfect reproduction. The nature of the imperfections must be themselves inheritable, and relevant to the ability of the organism to survive. This logically leads to a need for a clearly defined parent child relationship (this would exclude fire).
I am not sure about this, there may be a way to (clone) that is natural
to some alien life form, not very good for enviromental adaptation, but
if said enviroment is stable over large time scales evolution may be
un neccesary.
A born optomist
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quote:
Originally posted by wolram
b) It must be the product of imperfect reproduction. The nature of the imperfections must be themselves inheritable, and relevant to the ability of the organism to survive. This logically leads to a need for a clearly defined parent child relationship (this would exclude fire).
I am not sure about this, there may be a way to (clone) that is natural
to some alien life form, not very good for enviromental adaptation, but
if said enviroment is stable over large time scales evolution may be
un neccesary.
A born optomist
The only stable environment is a sterile environment (i.e. a dead environment).
More directly, if we find a life form that is incapable of evolution, how would you suggest the life form evolved in the first place (unless we accept intelligent design as a mechanism)?
George
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More directly, if we find a life form that is incapable of evolution, how would you suggest the life form evolved in the first place (unless we accept intelligent design as a mechanism)?
No ID, is not in my book [:)] i do find it interesting trying to define
life, and the possible forms it may take, even if there is life other than ours in the u, i guess any advantage to humanity would require higher intelligence, or least a life form that can develop thinking on
a par with ours.
A born optomist