From: robadob 31/10/2000 14:06:00 Subject: seed pod earth post id: 160693 Meaning of life the universe and every thing, in the time it takes to make a coffee. think of the earth as a seed pod ,its job is to create and sustain as much life as possible until our sun explodes. then as the sun explodes it smashes the earth to pieces ,sending fragments flying of in to space at a great speed. [a bit like when you blow dandelion seed things] the side of the earth that was in darkness would be protected to some point by the earth's mass. as these small parts of the earth were trust in to space they would instantly freeze and tiny micros of life would stay viable for ever. and then start a journey that am take maybe millions of years. as these particles of our earth when a long that would pick up ice and dust particles that would help to incrust the frozen life particles to help them survive there hopeful re-entry to another planet. there for if this is how we got here it would mean that we could be directly related to all other life in the universe, From: Edward ® 31/10/2000 14:12:00 Subject: re: seed pod earth post id: 160695 I was of the impression that everything will burn to a cinder, engulfed in the swollen carona before any exploding happens. From: boxhead 31/10/2000 14:15:00 Subject: re: seed pod earth post id: 160697 What if the human race is the seed that is supposed to go out into the universe and colonise new worlds. Thats a lot of pressure on the next couple of generations as we have the best chance of getting the necessary start before the best source of high energy fuel runs out. From: James R (Avatar) 31/10/2000 14:18:00 Subject: re: seed pod earth post id: 160699 It is an interesting idea that life on Earth was "seeded" from space. This is possible, but I don't think that many biologists agree it is the most likely explanation for life on Earth. When our sun goes into the red giant phase, the oceans of Earth will boil away. Temperatures on all parts of the Earth will become unbearable for life. Our sun will not blow up, although it will blow off some of its outer layers. It will then shrink, ending its life as a white dwarf star. JR From: Drues 31/10/2000 14:21:00 Subject: re: seed pod earth post id: 160700 Good theory Robbo! Sounds feasible, however, AFAIK the earth won't be "blown up", but engulfed and eaten by the sun. This process will almost definitely destroy all of the sensitive bio-compounds that can be used to start life (if you think like a Darwinist), and none of them will be shot into space. However, if it did happen, I could imagine such compounds floating around space, and getting them onto another planet to spawn life as happened here is not impossible. I'm not aware of a chemical's ability to leave space and enter a planet intact, but no doubt amino acids and the like could make the transition. An interesting endnote is that there are already organic compounds floating around in space. I read an article about how astronomers have found smallish clouds of ammonia and related organics in space, so maybe this is similar to the scenario you are thinking about. For those who don't know, ammonia can be used as a basis for organic compounds such as amino acids. From: robadob 31/10/2000 14:39:00 Subject: re: seed pod earth post id: 160708 would the sun's do the big burning engulfing thing every time or could there be a senrio where it could just blow up even if it was only one in a thousand From: B.C. ® 31/10/2000 15:20:00 Subject: re: seed pod earth post id: 160737 Our sun in around 4 or 5 billion years time will be nearing the end of it's life. It will swell as it uses up its hydrogen, and become a red giant. it will be big enough to engulf earth. Suns that are considerably larger than our sun will go super-nova or the conventional explosion that you are referring to. What is left from these stars are neutron stars or black holes. So the ultimate fate of any star is determined by it's size and colour. From: John Devers ® 31/10/2000 18:56:00 Subject: re: seed pod earth post id: 160952 To save the thread I'll say there is a 99.9% chance that lumps of rock containing bacteria have already left this planet millions of years ago when ejected by comets hitting the Earth. My question is could they achieve the velocity to leave the solar system or would they have to hitch a one in a billion chance ride on an asteroid passing through the system? From: Greg L. ® 01/11/2000 1:36:00 Subject: re: seed pod earth post id: 161225 Your idea is interesting Robadob but it has been though of before. You have actually touched upon some very interesting questions and ideas. The idea that life may have not originated on Earth and may have come from outer space (and I'm not refering to the UFO claptrap) goes back a fair way. Lord Kelvin (distinguished Scottish physicist of the 19th century) suggested Earth may have been 'seeded' by meteorites from space, and the main proponent in this century has been the maverick astronomer Fred Hoyle. Hoyle was a rather unconventional character, also being the co-creator of the 'Steady-State' cosmological model of the universe and one of the key figures in understanding stellar nucleosynthesis inside stars like the sun. The general idea that life (or the ingredients of it) may have come from outer space is known as Panspermia . Now this may at first seem like a silly idea. How can life possibly come from outer space? It turns out though, that there is plenty of good evidence to support this hypothesis. Let's start with the origin of life, one of the most hotly contested questions considered by thinkers down the ages. Most biologists today accept that evolution is the best paradigm for understanding how life evolved to the forms we see today. I'm not a biologist, so I can't really give a detailed run-down of the theory (read some books by Richard Dawkins or read Darwin's book itself-it's still in print). However, I can say that during the early history of the Earth conditions were not exactly conducive to the formation or the existence of life. During the final stages of Earth's accretion from the solar nebulae there was a stage from between 4-4500 million years ago when the last remaining planetismals were being 'swept up' and colliding with the proto-Earth in it's accretion zone. Simulations showed that inside Earth's accretion zone (Hartmann & Davis, 1975), (Wetherill, 1976, 1990) showed that bodies from 4000 to 6000 km (roughly the size of Mars or Mercury) may have formed in Earth's accretion zone. There also would have no doubt been many smaller (but still very large) planetesimals inside Earth's accretion zone. The Earth would have undoubtedly collided with some of these objects and the energies released would have been unimaginable. To give an example, a Mars-sized body is believed to have smashed into the proto-Earth during this stage. The result would have been the destruction of the two bodies involved, with the Mars-sized body melting entirely with its iron core sinking into the core of the former 'proto-Earth' and a plume of hot mantle debris being flung into Earth's orbit. Simulations have shown that this plume of debris could have cooled and then aggregated into the moon (Cameron & Ward, 1976), (Carnup & Esposito, 1996). So what relevance does this final impact period have to life on Earth? Well obviously with such energetic impacts occurring, the possibility of life forming on Earth's surface is somewhat reduced. The Earth's surface would have been melted to a considerable extent, and any water would probably be vaporised into water vapor and remain that way for a considerable amount of time. The early Earth also would have lacked a ozone layer, and the rate of geological activity would be higher than it was today. In short, conditions would have been extremely hostile. From: Greg L. ® 01/11/2000 2:02:00 Subject: re: seed pod earth post id: 161235 Now due to the extreme hostility of Earth's early surface, scientists have proposed a number of theories to explain how life may have began. Recently, bacteria have been discovered living in very hostile environments that were thought not to be capable of supporting life. Usually this life comes in the form of very hardy bacteria called 'extremeophiles' which can withstand radiation, intense temperature variations, vacuums, lack of oxygen, lack of sunlight, and so on. These sorts of bacteria are thought of to be amongst the most primitive due to their simple structures and ability to withstand extreme environments. They are also the key to the 'panspermia' hypothesis in its modern form. In 1996 NASA researcher David McKay along with eight colleagues announced they had found evidence for possible microbes inside a 'SNC' meteorite (Alan Hills 84001). (Hartmann, 1999). SNC meteorites are meteorites believed to have been derived from the planet Mars. SNC meteorites are typically 1.3 billion years old (vastly younger than ordinary meteorites) and display Oxygen isotope ratios ruling out an origin from either the moon or the Earth. Mars was suggested as a source, and simulations showed that out of the particles ejected from the Martian surface at about 1km/sec greater than the Martian escape velocity, 8% of these eventually impact Earth. (Hartmann, 1999). The AH 84001 meteorite was believed to be an ancient fragment of Mars blasted off Mars and that came to Earth in such a manner (it was found in Antarctica). Hartmann sums up the basic facts and ideas very well: Facts that are not in dispute include these: 1) The Martian Rock is very old, having formed about 4500 million years ago. 2) Its fractures contain globules of carbonate indicating liquid water percolated through the rock in the past. 3) Organic molecules called polycyclic aromatic hydrocarbons (PAH's) were found inside the rock. 4) Other organic molecules, including amino acids, were present. 5) Peculiar microbe-like structures were photographed. From: Greg L. ® 01/11/2000 2:34:00 Subject: re: seed pod earth post id: 161241 (continued from previous post) Mckay and his team used electron microscope images to reveal the latter small structures, 20 to 200 nm in size. They look vaguely organic, and some look like terrestrial microbes, including some found in basalts. These structures were not concentrated towards the rock's surface, as might be expected from terrestrial contamination. Mckay's team emphasized, even in their initial paper, that 'none of these observations by itself is conclusive evidence for past life', but that the ensemble of traits suggested that the structures might be fossil microbes that had existed in the ancient past when water ran on Mars. (Hartmann, 1999). The repercussions of this find were astounding. Although the conclusions of the authors were later called strongly into doubt, the meteorite gave an enourmous boost to the hypothesis that life may have existed on Mars in the very ancient past, and that organic compounds (and possibly bacteria) could be transported in some form or another aboard meteorites. Some researchers have proposed the hypothesis that the young Earth may well have been 'seeded' with either bacteria or complex organic compounds derived from the planet Mars, and life on Earth may well have got a toehold from thereon in. Life has existed on Earth for at least 3400 million years (Hartmann, 1999), however, its exact point of origin in time and how it formed is a matter of debate. The proponents of panspermia have used the arguments outlined above and also broadened them to include ideas including 1) Life on Earth may have been helped along by water and organic compounds brought to the Earth by asteroids, comets and meteorites. This is quite a valid argument, as meteorites known as Carbonaceous Chondrites are known to contain water and to be rich in organic compounds, and asteroids and comets also contain water, ices and carbon compounds (Hartmann, 1999). 2) The abundance of organic compounds in space suggests that planets (with suitable conditions) can easily be seeded with these compounds. Observations of cool molecular gas clouds in the 1970's have indeed shown that complex organic molecules can form inside these environments. The cool and dense environments inside molecular dust clouds allows molecules and dust grains to collide frequently and form complex organic molecules, such as water, ammonia, formaldehyde and ethyl alcohol. (Hartmann, 1999). [Interestingly, Dr Karl used the stupendous amount of alcohol present in one gas cloud in one of his 'Think before you drink' ads :) ] 3) In the case of Mars, that hardy bacteria were 'blown' off the surface during a meteorite impact during the planets very early history (3000-4000 million years ago) and would have been transported inside an impact fragment. Provided the hardy bacteria were deep enough inside the rock (and finding hardy bacteria in rocks is not a problem) they would have been sufficiently shielded from the harsh conditions of space. As the orbits of Earth crossing meteorites have time scales of only a few million years before they impact Earth, this would easily give sufficiently protected dormant bacteria (or spores) enough time to be transported from planet to planet. In addition, during the final accretion phase impacts would have been quite frequent, so presumably bacteria from Mars had many chances to get to Earth. From: robadob 01/11/2000 2:50:00 Subject: re: seed pod earth post id: 161243 if mars had life then it would have been seeded why would'nt earth have been seeded at the same time that could mean life on mars and earth were related but that life here didn't come from mars but the original sores From: Greg L. ® 01/11/2000 3:16:00 Subject: re: seed pod earth post id: 161246 So, that is 'panspermia'. Although the idea of panspermia is popular with some scientists, the consensus amongst scientists seems to be life did originate on Earth, and not elsewhere. Nevertheless, it is a very interesting idea that needs to be scrutinized thoroughly. Now to the second part of your idea. Your thinking is o.k., but unfortunately astrophysical theory predicts otherwise. The sun will not 'explode' as a supernova as it doesn't have enough mass to become one. Stars with masses of eight solar masses or more end their lives by going through a series of fusion reactions at the core until iron is produced. When this happens, fusion ceases and the star collapses inwards. The core is crushed either into a neutron star or BH (depending upon the mass-if the collapsing core exceeds three solar masses it will most likely form a BH) and releases a huge amount of energy and particles in the process, blowing off the star's outer layers into space. Any planets in the system would be blasted with intense radiation and particles, probably to the degree that they would either melt or be destroyed entirely. Our sun, however, will die a quieter death. When it leaves the main sequence it will swell up into a red giant and will eventually puff off its outer layers into space, leaving behind a white dwarf and a planetary nebula. During the red giant phase Mercury and Venus will be destroyed, whilst the Earth will be cooked to a cinder (the crust will almost certainly melt). Even the hardiest life will be destroyed, and the Earth will be rendered lifeless (if it survives anyway). Once the sun's red-giant phase ends, it will be little more than a white dwarf that will steadily dim as time goes on. So far as life goes, its more or less 'curtains' so far as our solar system goes (unless there is anything surviving in Europa, which would be at a fairly safe distance). However, could life reside in a meteorite derived from Earth? It is possible, although Earth has a fairly high escape velocity (about 11 km/sec from memory). However, Earth, like all other planets, does get hit from time to time by asteroids and comets, and an impact with enough energy should occur in the timescales between now and the death of the biosphere (about 1000-3000 million years from now). Could a meteorite escape from the solar system? The escape velocity from a body of mass M and radius r is given by the relation Vesc=sqrt(2GM/r) where G is the gravitational constant. To escape from the solar system from earth's orbit, you need a velocity of about 42 km/sec or 151,200 km/hour, which is quite fast. An encounter with a large planet such as Jupiter may be enough to impart the meteorite with a high enough velocity to escape the solar system in a 'hyperbolic' orbit, provided its orbit brings it close enough to Jupiter. Once in interstellar space the journey to the next star system may take aeons, as interstellar distances are vast . Even a light year is a distance of trillions of kilometers, and the nearest star is about 4.2 light-years away. You don't need to do the math to see that it would take our meteorite many millions, perhaps billions of years to reach another solar system. Personally, I would say that there would be a greater chance of life coming into being inside a suitable system than being transported there from an outside solar system. Another possbility is that humans may deliberatly aim organisms towards sunlike solar systems to spread life (in case we die out) but this idea is still in the realms of science fiction (see Stephen Baxter's Titan for example). You should explore the topic further if you can. Bibliography and suggested reading: Hartmann, William K, Moons and Planets, 4th Edition Wadsworth Publishing Company, 1999. Davies, Paul, The fifth miracle http://www.panspermia.org/ for ideas and evidence on panspermia. From: Greg L. ® 01/11/2000 3:38:00 Subject: re: seed pod earth post id: 161247 Good point, Robadob, but I'd say that the probabilities of life arising in our own system and then being transported from planet to planet would be the most likely scenario, is panspermia is correct. As I said earlier, about 8% of the stuff blown of Mars ends up on Earth, and whilst I don't know the detailed math to prove it, the chances of a random asteroid coming in from interstellar space and 'seeding' the solar system would be extremely remote. Whilst I cannot rule it out as an impossibility, weighing the relative likelihoods of each event, the logical one to choose is that life arose in our own solar system. A reply to this might be 'But aliens may have seeded our solar system.' Again, this may be possible but it is exceedingly remote, and my principle would be 'extraordinary claims require extraordinary evidence'. The discovery of hardy bacteria in harsh environments on Earth and the widespread availability of organic compounds in the solar system would definitely suggest strongly that life could arise naturally through random chemical reactions. We should apply 'Occam's Razor' and adopt the simplest hypothesis-that life arose naturally, within our own solar system by evolution and random chemical reactions. I am really only concerned with the how, not the why (a question better left to philosophers and theologians. To John Devers: Yes it is possible for an object to gain enough velocity to a solar system. The problem however, would be to give it a strong enough 'boost'. I'd say that an impact on Earth or Mars would not have enough energy to send an object into interstellar space, but an encounter or two with Jupiter under the right conditions should give an asteroid in the right orbit enough velocity to escape. Some of the planetesimals are believed to have been ejected into interstellar space. I can't prove it mathematically, but I'll look it up if I can. From: John Devers ® 01/11/2000 3:52:00 Subject: re: seed pod earth post id: 161248 Maybe the original building blocks of life were produced in the big bang and the whole universe is teaming with bacteria at least on all of the trillions of earth like planets. Thanks for those escape velocities Greg L. From: Paul H. 01/11/2000 8:04:00 Subject: re: seed pod earth post id: 161262 The well-informed Greg said: >> 'But aliens may have seeded our solar system.' Again, this may be possible but it is exceedingly remote, and my principle would be 'extraordinary claims require extraordinary evidence'. Why is it an extraordinary claim? What makes you think it's a 'exceedingly remote' possibility? What's your evidence for this claim? The fact is we have no idea how likely it is. For all we know, the origins of Life may have been in deep space. Even interstellar space. For all we know interstellar space may be teeming with unimagined ecosystems, parts of which have adapted to the hostile stellar environments of planets like Earth. The recent apparent discovery of interstellar "planets", previously unimagined, reminds us just how little we really know about what's Out There. My principle would be that whatever we imagine about the unknown, nature usually comes up something an order of magnitude more complex, beautiful, and amazing. regards, Paul "keeping our solar-planet-carbon-water bias in mind" H. This forum is un-moderated. The views and opinions expressed are those of the individual poster and not the ABC. The ABC reserves the right to remove offensive or inappropriate messages.