I think our perception of life is subective to our own form. Moving from complex organisms to simpler mono-cellular organisam like viruses, or moving from scintifically recognisable to imaginatively possible. What is the simplest? And what is farthest that we have reached in our effort to understand and define life?
124660
Probably not, at least not on this planet. Life as we know it incorporates nucleic acid within a cellular body (ie bacteria, human cells).  Prions are not alive, nor are viruses, according to the strict definition of biologists: Does it consume nutrients and convert it to energy?  Does it replicate without a host?  Does it excrete waste?  There are other standards, too.  Basically all cellular organisms fit into this definition does, but viruses are simply packaged DNA/RNA and protein.  Prions are just proteins, not alive.
116439
Supposedly the universe is estimated to be about 13.6 billion years old.  I think I read that on Wikipedia, though, so you never know...\n\nThat said, I really have so little idea what is out there or what conditions are necessary for life to arise that I don't know which theory is more plausible.  How flexible are the conditions that lead to the formation of primative cells on Earth?  Can there be life based on an entirely different set of molecules?  An entirely different set of elements (i.e. not carbon based)?  How many other planets have chemical compositions and climates like Earth?  Did life even originate on Earth? (I've heard the theory that primative cells could have originated on another planet and been brought here on an asteroid).  Could primative cells have left Earth on some sort of asteroid and taken up residence elsewhere?\n\nI'd like to think there's other life out there, just because it makes things more interesting.  Until I have reason to believe otherwise, I'll assume there is.
422098
It's hardly surprising that we can see no sign of life out there.  Views of Earth taken from unmanned explorer craft like Voyager taken from within our own solar system show no signs of life either. If you can't see elephants, whales or even forests from only a few million miles away then looking at hazy dots that are planets thousands of light years away expecting to see obvious signs of life is a bit optimistic.\n\nIn addition, given the size of the Universe we can hardly claim to have looked everywhere whilst at the same time it seems inconceivable that some form of life has not evolved somewhere else.\n\nSpectroscopic analysis of stellar nebulae and other "gas clouds" in deep space has revealed the existence of basic organic compounds such as amino acids which are regarded as fundamental building blocks of all living things here on Earth. So if life itself hasn't been located elsewhere, some of the prerequisite precursors certainly have.\n\nThere are also several "fossils" found on meteorites believed to have come from Mars which may or may not prove to be the remains of living things which originated on Mars.
88845
hmmmm now your getting into ethics...to create any life form that is unaware of itself and designed to simply  serve us sounds more like slavery.. any live   being would have to have some type of brain/ intelligence if only to just carry out its assignments...hence it would be capable of feelings/ pain/   joy / hunger etc..... we as humans I would hope are too humane to   engineer and enslave such a being...so   I would have to choose a metal robot  , though personally I would choose neither...since either would be one more step in  removing the  satisfaction of having done your own work/  and completed your own project...
501756
Yes, this is assumed to be the case, and much has been written on it, but little is known in detail. The first life form, or the ancestor of life, depending on how you define things, is generally presumed to have been a single molecule or small group of molecules capable of doing two things: 1 Catalyze reactions in its environment that lead to a copy of itself being assembled and 2 be nontrivial enough in structure so that slight changes can result in mutations still capable of performing number 1. 1 has been achieved in highly specialized environments, but not 2. To be a candidate for the first natural life, 1 would have to be possible in the natural environment of the time. Until such is found, there will remain a gap in our understanding that some will prefer to explain by the action of their God of the Gaps.\n\nI've listed one book that discusses such speculations.
66817
This answer really relates to sensation and perception.  Sensation is the act of detecting incoming environmental information via sensory organs.  Perception is the interpretation, the assigning of meaning to sensation.  Since we can break down the electromagnetic spectrum, and understand the potential environemental energies, there would be no surprise there.  \n\nHowever, perception would be based upon the types of sensory organs and also the equivalent "neural" system being used by a lifeform.  Perceptually, a lifeform dissimilar to that of ours MIGHT perceive things QUITE differently.\n\nJust in the human species, there are people who perceive colors through other senses (see Synaesthesia link below).
412150
think about this.. its doubtful you'd realize anything unless you prepared for it... and when you think about it, what exactly is being judged?? this "I.." Where does this "I" or me actually exist.. the physical isn't me because it is blood, muscles, cells, bones, nervous system, etc.. The mental isn't me because its made up of form, feeling, discrimination, compositional factors, and consciousness... These physical and mental factors broken down make up the  "Self."\n\nall together, the self existing "I" does not exist anywhere.. But something exists... We exist, but only in dependence to all the infinite factors internal and external, which are constantly changing... We exist, but not as we appear to exist..  So if anyone judges you, just ask them, "what exactly are you judging and where is it?" see if they can actually prove you exist without dependence... Cheers!
644994
Good question. Again what is life?
511450
Our surroundings and out physical make-up is how the periodic table relates to us. We are comprised of some of these substances and the environment we live in is also comprised. It's the basic formula for life. I hoep that maybe got the ball rollinga  bit, i was trying to think of it also and can understand why it is hard to come up with. Best of luck.
75079
Alien? What's that?\n\nI think there is a huge statistical probability that LIFE exists somewhere else. And that may be as simple as uncicell forms of life. It may also be another form of life we've never seen on earth.\n\nBut "aliens" as we see in movies, sure not!!!
164149
The first living cells were (big word coming up) heterotrophic anaerobes. This meant that they were other feeders (fed on naturally occuring amino acids) without oxygen. It wasn't until later that photosynthetic (organisms able to use energy from the Sun) developed. \n\nhttp://www.windows.ucar.edu/tour/link=/kids_space/qlife_ani.html\n\nThere is still debate within the scintific community if viruses are actually living.  The need a living host in order to function and reproduce.\n\nhttp://www.beyondbooks.com/lif72/2c.asp
164379
This is a more complex question than it seems. In order to fully define Death we would have to fully define Life, and that has not been done yet. Life can be described, and there is the Cell Theory of Life, but what 'life' is, no one can say yet.\nHowever, it is plain that everything living moves somehow, and that it reproduces somehow, and that whatever is living must use and excrete whatever substances it needs in order to keep on living. In most cases we are talking here about nutrition and respiration, respiration being the more critical. When respiration ceases either on a cellular level or throughout the entire organism, everything shuts down, because chemical reactions in the cells and between them can no longer take place. Some bacteria will go into a spore stage when this happens, and can thus survive extremes of temperatures and dehydration (like anthrax and TB). Generally in the absence of oxygen, cells lose their ph balance and become acidic, which upsets all chemical reactions in the cell. Conversely, anaerobic bacteria like botulism, when exposed to oxygen, go through a similar process of having all chemical reactions messed up.\nTherefore, although we cannot say what exactly 'death' is, we recognize it in animals by: an absence of respiration, an absence of pulse, an absence of reflexes (due to brain and nerve death), an absence of sensation, an absence of conciousness, and an inability to eat or reproduce. It is further noted by an absence of brain wave activity.\nIn plants death is noted by an inability to rehydrate, lack of response to stimuli, inability to reproduce or respire, and limpness.\nIn microbes, death is noted by an absence of cell division or reproduction, or by bursting of the cell walls.
651386
Within 1000 LY? Our Milky Way has (as Carl Sagan use to say) Billion and Billions of stars. If only 1% of those stars could support life and of those if only1% of those had intelligent life there would still be hundreds of millions of intelligent life forms. \n\nAs for advanced life forms I'd like to think we are about average, meaning that there are those who are more advanced and conversely those that are less advanced. \n\nHaving said that, communication is a different matter. We know that Dolphins have a large brain and we can hardly understand them (and we're on the same planet). Distance comes into play when communicating with interstellar beings. We have been sending radio waves into space for ... what... 75... 100 years. But only since 1936 have we had the capability to send strong detectable signals. Assume the same for our closest neighbour. Let us assume that since we have not heard from them that they are at least 70 LY away. Their signal might be on its way but how long have we actually been looking for that signal (20 years?) They are getting our signal from 1936, now. In 70 years we might get a message from them and then another 70 years for them to receive our response. The problem with communication like that is it takes 140 years to get an answer from your first question. By that time you may have solved it yourself, or things may have changed so much that the answer you receive is entirely irrelevant.\n\nAs for Immortality... that is more philosophical. If you believe that we turn to dust and become food for the worms and there is nothing else to it then... no they have not achieved immortality. The most advanced beings may have found ways to increase the life span to the point of verging on immortality. But for even them death would be an eventuality. \nOf course if you believe that the soul (or spirit) that gives us "life" is immortal then we have achieved it already and so would other beings.\n\nWhat they look like... wow... the imagination is the limit. Let say that they followed our evolutionary path but there was no giant rock to smash into their world and wipe out the dinosaurs. They may have evolved as an intelligent lizard. They would need warm climates and would have to warm up before becoming active.  They might be strict carnivores or vegetarian. They could possess chameleon like properties both as a protective measure and as a hunting tool.\nMaybe they are insectoids with many arms and legs and with exoskeletons and natural body armour. And they might be fast! Really fast!! (Ever seen a spider scamper across the floor think of how small it is and how much ground it covers in a short span of time). \nWe have even discovered some silicoid creatures in the deepest parts of our own oceans near "smokers" (volcanic vents on the sea floor). What if they were to rise to an intelligent life form they wouldn't need sunlight or plants or animals for food as they eat minerals. They could be very long lived and move very slowly (a message from them might come as a very slow transmission and go undetected for years because the modulation of the frequency might take hours [if not weeks or years] to change).\n\nIf there really is no other life out there what a waste of space!\n\nLive long and prosper. (and may the force be with you.)
445344
Hi. I do not think so. It may be possible that life forms unimagined may exist (I'd be surprised if they didn't) but they would still need to be based on something other than vacuum.
592006
You seem to have answered your own question there. Nobody knows exactly how the first living cell formed, of course, but it is generaly thorized to have begun with self-replicating molecules (RNA&DNA, like you said, though, belive RNA is belived to be the more ancient). These molecules reacting in a dense enough solution with the nesesary ingridients and enough energy thrown itno the mix, and hey persto -Life!
646074
An interesting question.  \n\n#1 would seem at first glance to be automatically false, as everyone will agree that there is evidence that there was a time when the things we see today in nature, did not exist.  But to get a little deeper, what if these things are the natural products of natural laws that have always existed?  E.g. what if our universe is just one of an endless series of universes that appear, unfold under natural laws that have been in existence for eternity, and then disappear, only to get reborn again as a new universe?\n\n#2 is the *goal* of a scientific explanation.  I.e. to see how much we can explain by the discovery of natural laws.  Science has no way of knowing if such an explanation will always be possible, but it has to try.  And so far we have done remarkably well ... almost everything we see in nature can be explained in terms of the operation of natural laws.  And natural laws can often be shown to derivable from simpler natural laws.  (E.g., that's why physicists are on a quest to unify the four forces of physics ... so that all laws of atomic physics can be derived from a single law.)  However, scientists will always be faced with the question of where these simplest of natural laws came from.  And they may have to settle for the answer "they seem to have always been there", which brings us back to #1.\n\n#3, and #4 need more definitions to distinguish them.  What do you mean by phrases like "beyond nature", and "intelligence."  \n\nHOWEVER, despite being a died-in-the-wool evolutionist, I lean towards #4, (an intelligent, supernatural origin for all things in nature) but not with in the same sense as Intelligent Design.  I *don't* believe some intelligence designed every cell membrane, every flagellum, every eyeball, every bird, bat, or insect wing, every endochrine cycle, etc.  Evolution provides a far more satisfactory explanation for all those things based on such simple natural laws as the law of natural selection.  \n\nBut I do wonder where that force of natural selection, as a natural law, came from.   I believe it will be shown to be derivable from simpler laws of chemistry and thermodynamics, which can be derived from even simpler laws of physics.  But ultimately, we will still be faced with wondering where those primary laws of physics came from.
153856
At the present time, we just don't know.  If you saw pictures of aliens, what you saw were fake.  Nobody on earth has yet to produce a verifiable image, photographic, electronic or hand-drawn, of a living creature that originated elsewhere in the universe than from our home planet.  Nobody.\n\nAlso, at the present time, we suspect that there is no other planet in any nearby solar system that's host to a sentient race of beings like us.  That does not mean that some form of what we call "life" is impossible, but just think: out of the billions of living critters that now inhabit, or did in the past, our home planet, only one of those life forms evolved to the point where it (us) can even begin to think about such questions.  That by itself will tell ya we're sorta unique! ;-)\n\nIt sure would be interesting, wouldn't it?  But imagine if you will what it might be like if those alien creatures we fantasize about were an advanced race of carnivores that look upon us as another breed of cattle, fit only for eating!  Yow!  Or, how about if they were friendly, warm and fuzzy folks who just love to make nice with us - but they carry an infectious disease that there's no cure for.  Oh boy.  Or maybe, like Darth Vader, they just consider us a nusiance worthy of one blast from a super-mega cannon that blows Earth into dust?  Whoa!  Hey dude: you SURE you wanna meet aliens?  \n\nAll this is just idle speculation.  The hard fact is, even if there were creatures just like us somewhere in the universe, we are not gonna know about it, because the distances between them and us are just too great to permit interstellar travel, the hazards of such a trip are insurmountable, and no means of communication can travel fast enough for us to hear from them and be able to answer back.  Kind of a bummer, isn't it?