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The first stars to form were extremely massive -- typically, more
massive than the most massive stars existing today. They would have had very short lifetimes before going supernova. It is possible that such stars condensed in large numbers in a relatively short time (perhaps on the order of a hundred million years), once the gas had cooled enough to collapse gravitationally. If so, a few hundred million years after that, there would have been a tremendous number of supernovae in an equally short time period. Maybe thousands of supernovae per year in a galaxy the size of the Milky Way. That was so long ago that, if there was such an outburst of supernovae, the light from them has been redshifted into the microwave part of the spectrum, and is very faint with extreme distance, so it will be very hard to detect now, even though it would have been very bright at the time. Over the eons, star formation has evened out, and average star lifetimes have become much longer, so that a galaxy like the Milky Way only only produces about one new star each year, and only about one supernova in a hundred years. The vast majority of stars now are too small to ever go supernova. All the stars that were born in the first generation went supernova billions of years ago, spewing out heavier elements which got into later generations of stars and made them different from the first generation: Less massive and longer-lived. The average star will shine for tens of billions of years before gradually shrinking and dimming. Our own Sun, somewhat more massive than average, formed about 4.5 billion years ago, and is at about the middle of its lifetime right now. A total expected life of between eight and ten billion years. It will not go nova, but will puff off outer layers of its atmosphere, making a planetary nebula, before it collapses into a white dwarf. It will then slowly cool off over hundreds of billions of years. Only the very few most massive stars can go supernova. -- Jeff, in Minneapolis
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http://www.FreeMars.org/jeff/ "The other planets? Well, they just happen to be there, but the point of rockets is to explore them!" -- Kai Yeves |
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Yes, I to enjoy a good discussion. My best advise to you is to explain the frequency of super nova is such that you may never see one. Yes the Universe is a very big field. Just estimating the number of galaxy present is a daunting task. A very large number. With the stars per Galaxy set at about 300 - 500 million stars. ( Thats just a guess ) You would think that we might see more Nova.
No, because the time scale of a human life is such a small part of the time line of the universe. This is not a bad thing as these super nova things could be the last thing you see. Astronomers tell us that we are safe. There is no or very little chance of a too near to us nova. Phew! I trust the following does not offend; It's not intended to. . . After a public viewing session at the local observatory. A distractingly attractive young woman stepped up to us as we were closing the observatory and asked, " The splendor of it all must leave you pondering why ?" Without getting into the subject because to do so might offend. How would you have answered her. A colleague of mine whom is not known for diplomacy was about to answer. I interrupted him with. " We are interested in imparting our knowledge of the science of astronomy. To Speculate why , who or how will simply do your head in. Leave those big questions to the elders among st your group." Even she saw the mirth of it. |
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1) The Universe is billions of years old, not infinitely old, so the amount of supernova light that can reach our eyes is limited by the number of supernovae that have had time to occur since the Universe began. 2) The huge majority of such supernovae occur in parts of the expanding Universe that have high red-shifts relative to our own location, so their light is very much dimmed relative to nearby supernovae. BTW: there's an error/omission on the Wiki page that ss002d6252 linked to. I don't know if Mandelbrot ever discussed a fractal Universe as a resolution to Olber's paradox, but the idea significantly predates both fractals and Mandelbrot: Carl Charlier proposed what was called "hierarchical cosmology" as a resolution to Olbers, in the early 1900s. Grant Hutchison |
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Actually, I think it would be a shame to miss the opportunity, in this situation, to seek common ground with the creationist. As long as the debate is couched in terms of a confrontation, you are doomed to fail, if your goal is alter the opinion of the creationist. If you say "you're wrong", they will hear, "your faith is baseless", and you will move them not one iota no matter what the power of your logic. On the other hand, if you recognize that the fact that we don't see supernovae filling the sky is an important piece of scientific evidence, then you have a base for common ground. The issue is really, what can we conclude from this observed fact? The creationist error is not in concept, it is in timescale. You can start by agreeing with them that the observation does indeed set an upper limit on how old the universe can be. What a great place to start--- agreement! Now you turn to the issue of what is that upper limit. At this point, you can talk about supernova rates etc., and point out that astronomers place the limit at the level of many billions of years (probably much longer, but that doesn't really matter). The only real flaw in the creationist's argument is that he/she made the numbers up, but the idea is right. It is quite significant that modern observations support the idea that the age of the universe is finite. So then the debate turns to what the timescale is, and for that issue, the creationist will be woefully ill prepared to debate and will have to admit that they really don't know what the upper age limit is. Then you get them to accept it is many billions of years, and that this is completely consistent with the Big Bang, and you may move their understanding a little.
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I suspect the usefulness of the sort of approach Ken recommends is in winning over anyone else who's listening in and undecided. Although it's extremely rude, I confess I'd turn to any such spectators and address my answer to them.
Creationists who offer these little half-digested titbits, in my experience, are parroting them from pamphlets and websites with lists of "Tricky Questions to ask Scientists". They often have little understanding of the point they're raising, and will simply grow defensive (or shift ground to the next question on their list) if you try to enter into debate. I also wonder about pitching the argument lower. We recognize Olbers when we see him, but most folk don't. You could produce a reasonable analogy by turning the question around: If we've had artificial light for a hundred years, why isn't the whole world brightly lit by now? 1) People turn the lights on and off 2) Light moves fast, so it disappears into the rest of the Universe when the lights are turned off 3) Most of the lights are too far away for us to see, anyway If anyone says "Yes, but ..." you can turn that into a discussion of Olbers reasonably enough, but I think just that response will knock the whole thing on the head, as far as your average creationist is concerned. Then you have to brace yourself for the next question on the prepared list ... Grant Hutchison |
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Thanks everyone. Some of the responses were things I didn't have any idea about (such as the kinds of stars being born at different times during the age of the unvierse), and some were embarassingly obvious, and I should have realized them on my own (redshift).
The trouble with debating creationists is that, in my experience, no matter what data you present to them, when they reach the point that they can't answer you with the soundbytes they're fed online and in church, they fall back on, "that's just your opinion," "how do you know, were you there?" and "Science changes all the time, so you can't be sure what you're saying is right." It's difficult nigh unto impossible to get them to admit that any part of their arguments are wrong, because they really believe that they're working from a completely inerrant document, and they're unwilling even to admit to errors in extrapolation from it. However, I don't think that the debates are truly fruitless. After all, as grant mentioned, whether or not you convince your opponent of anything, you may help educate the lurkers. Also, these debates have widened my interest from Philosophy and Biology into astronomy and physics. I started learning about the latter because of the debates I often engage in, and from that start, I've become really fascinated, and am trying to learn as much as I can now. Even if my opponent leaves thinking that I'm a hopeless heathen, I still appreciate the exchange, because it serves as a vehicle for me to learn more about subjects I haven't previously studied. |
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When dealing with creationists, always start your search with the venerable Talk.Origins Archive. Therein you will find this: Supernovae, Supernova Remnants and Young Earth Creationism FAQ. I first encountered the SNR argument over a decade ago, and it originated with a Canadian educator who knew far less about astronomy & supernovae than he would ever realize. The bottom line sound bite is that creationists consistently vastly overestimate the visibility of SNR. They have no concept of "confusion" in a crowded sky, a problem that real astronomers deal with regularly. New SNR are still being discovered today, and it is not uncommon for someone to realize that some object we have been looking at for all these years is actually an old SNR.
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Don't try this at home - We're what you call "professionals" - MythBusters. |
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Apart from that, don't stars have to reach a certain age, well in excess of
6,000 years, before they can become supernovae? So, if supernovae are observed, the universe is very old, by human standards. Last edited by Halcyon Dayz; 13-June-2006 at 05:28 PM. |
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It sounds like Tim is raising the issue of objections centered on supernova remnants in our galaxy, rather than the light from very distant supernovae. That would make it an argument about the age of our galaxy, rather than about Olbers' paradox, which is apparently also raised by creationists. In that case as well, the answer rests on the issue of timescale, there can be agreement on the question of finite age. The importance of that agreement is significant, in terms of finding a common ground. But ultimately, I think the key is agreeing in advance whether the search is for scientific, versus faith-based, truth.
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In addition to the light from super-novas being red-shifted, there's also the inverse square law to consider. Basically, the intensity of the light which reaches us falls off as 1/R^2 where R is the distance from the source to the observer. Many people do not fully appreciate just how rapidly the intensity diminishes with increasing distance.
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Here's my new contribution to this: "why? Why did God create old stars and supernovae remnant?" I'm guessing the response will be, "so that the universe will appear older." Now here comes the zinger: "if the universe was created so that it would appear to be billions of years old, then why would expect to see *more* supernovae remnants?? Are you saying that God did an incomplete job, that he made a big booboo when attempting to create an old universe? Do you think that God is up there in heaven saying to himself, 'DOH! I tried to make an old universe but I'm an idiot, I blew it, I totally forgot to make enough supernovae, wow I'm really embarrassed, it's a good thing there are creationists to point out my error.'" And this logic applies to lots of creationist arguments. "If God purposefully set out to create a universe that appears old, then why is it so easy for you to poke holes in his creation and point out evidence of a young universe?" |
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I have enjoyed reading all of your responses, and follwed everything including visible light shifting to the microwave part of the spectrum (now I see why the evidence of the big bang was found in microwaves). But, if visible light has been shifted to microwaves, wouldn't gamma and x-rays shift to visible light? And, don't supernova produce more gamm and x-rays than any other part of the spectrum?
On the creationist thread, I live in religious right country, North Georgia. I have seen once reasonable people become born again and ironicly embrace intolerance self rightiousness. There seems to be a competition between them to see who can hold the most outragiously unfounded beliefs: it is a badge of honor to be more superstitious and less fact based than the next believer. Once they go, I have never seen them come back, for they cannot allow reason to corrupt or erode their new fact free reality. Philip |
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Grant Hutchison |
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We need some decent epidemiology before we can decide whether a specific package of religious convictions has a net good or bad effect on society. Now that would be an interesting study to try to get through a government funding agency ... Grant Hutchison |
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And connected to that point is, how do you measure someone's religious convictions? If you just ask them, you face distortion due to hypocrisy, brainwashing, etc., but if you instead use their actions as a guide, then you are mixing your categorizations with the data you are trying to correlate. If someone goes to a particular church once a week and memorizes some pat phrases, yet exposes in their actions extremely opposite values, do they even qualify as one of the faithful in a study like that? There may be (at least) two separate types of adherent to religion, one type who is sincere and really tries to apply the tenets, and another type who just goes through the motions like a trained parakeet.
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