0 Members and 1 Guest are viewing this topic.
quote:Originally posted by neilepThanks 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
quote:Originally posted by another_someonequote:Originally posted by neilepThanks 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 beI 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
quote:Originally posted by wolramI agree Neil, when life on earth can exist in such extremes, fromgreat depths in the ocean around thermal vents, to the frozen wastes,and bacteria has been found deep in the earth, it would be a verystrange thing if we were the only ones in the u.A born optomist
quote:Originally posted by ukmickyOnce life has started then it can evolve to live almost anywhere in one form or anotherbut 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.
quote:This paper gives an overview of the extreme conditions that life can survive in.
quote:Originally posted by ukmickyquote: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
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.
quote: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.
quote:Originally posted by ukmickyRemember 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
quote:Originally posted by Soul SurferIt 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 barrierLearn, create, test and tellevolution rules in all thingsGod says so!
quote:Originally posted by neilepWe 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 ?
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.
quote:Originally posted by ukmickyophiolite 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 
quote:Originally posted by neilepIt'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.
quote: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!
quote: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.
quote:Originally posted by DoctorBeaverquote: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.Brand new forumhttp://beaverland.forumup.us/More than just science
quote:Originally posted by rosyRaditation 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.
quote:Originally posted by rosyRadiation 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.
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.
quote: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?
quote:Originally posted by ukmickyBasically 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
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.
quote:Originally posted by DoctorBeaverquote: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.
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.
quote:Originally posted by DoctorBeaverA 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.
quote: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?
quote:Originally posted by DoctorBeaverI'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.
quote:Originally posted by wolramIn my view life, must mean, (some thing) able to reproduce and evolve, inteligent life is quitedifferent, 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
quote:has one or two extra ingredients that afford it sentience
quote:Originally posted by neilepFire.It's birth is a spark. It grows, it spreads, it has offspring and dies, but it's clearly not 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.