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#21
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A quasar, too heavy to be true
In article , Gary
Harnagel writes: Yes, he was a priest, but, unlike some other scientists who are Christian (i.e., Christian scientists, not necessarily Christian Scientists), such as Don Page, he managed to keep the two areas separate. I didn't realize that about Don Page, or much about him at all. From this little treatise: http://www.preposterousuniverse.com/...and-cosmology/ One Bob Zannelli responded, "Don Page is a first rate cosmologist, and a very nice guy to boot. He is scrupulously honest and while I reject his evangelical Christianity I have great respect for him." I don't understand your denigration of him. As my history teacher used to say, just an observation, not a judgement. The point is that his belief does affect his science. He believes "that the universe was created by a...personal God...who relates to it as His creation" who also may have created "new heavens and new earth for us after death". (Quotation is from The Philosophy of Cosmology, edited by K. Chamcham, J. Silk, J. D. Barrow, and S. Saunders (Cambridge University Press), 2017.) This is not something he said in a pub, but something he wrote in a cosmology book. Because the Schwarzschild radius, as I already mentioned, applies in an asymptotically flat spacetime. That does not describe the universe. Well, that flat claim of yours doesn't agree with observation: https://en.wikipedia.org/wiki/Flatness_problem The flatness problem (about which I have written an entire paper) refers to the spatial flatness of the universe on large scales, not to Minkowski space (which is what the black hole is embedded in). You are confusing two different uses of "flat" here. (Again, maybe the moderator can insert some standard explanation here.) [[Mod. note -- There are three distinct concepts involved he (a) *Spacetime* as a whole can be flat, i.e., it's the Minkowski spacetime of special relativity, where the 4-dimensional spacetime Riemann tensor is zero. (b) A spacetime can be *asymptotically flat*, which means that there's a region "far away" where the gravitational field is small. This provides a setting to mathematically formalize such concepts as gravitational radiation, black holes, and measurements of gravitational radiation far away from its sources. (c) A spacetime (which may be non-flat) may be *spatially flat*, i.e., its 3-dimensional t=constant "spatial slices" (roughly speaking, these represent "all of space at a moment in time") may be flat (3-dimensional *spatial* Riemann tensor is zero). Such a spacetime may still have 4-dimensional spacetime curvature. A Venn diagram would show (a) as a single point, and (b) and (c) as partially overlapping regions (whose overlap contains (a)), within the larger region of all spacetimes. In the context of cosmology the universe in which we live is (c) to within experimental error. It is not (a) or (b). However, for astrophysics purposes other than cosmology (e.g., studying black holes and/or gravitational waves emitted by sources other than the big bang itself), it's a very very *very* good approximation to treat the universe as (b). I'll say a bit more about this approximation in a separate posting. -- jt]] Of course, this ASSUMES that the FLRW metric describes our universe. All observations suggest that out universe is well described by the FLRW metric. Since, as Don Page pointed out in the link given above, "We simply do not know whether or not our universe had a beginning." What actually happened at the beginning, if there was one, is a different question. My belief system says that it didn't. And I reject the "bounce" model, too. IOW, "big bangs" happen repeatedly without bouncing. In such a universe (multiverse?) curvature is only a "local" phenomenon. Science is not about belief. |
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A quasar, too heavy to be true
On Friday, December 29, 2017 at 8:18:56 AM UTC-7, Phillip Helbig (undress to
reply) wrote: In article , Gary Harnagel writes: Phillip wrote: Yes, he was a priest, but, unlike some other scientists who are Christian (i.e., Christian scientists, not necessarily Christian Scientists), such as Don Page, he managed to keep the two areas separate. I didn't realize that about Don Page, or much about him at all. From this little treatise: http://www.preposterousuniverse.com/...and-cosmology/ One Bob Zannelli responded, "Don Page is a first rate cosmologist, and a very nice guy to boot. He is scrupulously honest and while I reject his evangelical Christianity I have great respect for him." I don't understand your denigration of him. As my history teacher used to say, just an observation, not a judgement. I'm glad :-) However ... The point is that his belief does affect his science. He believes "that the universe was created by a...personal God...who relates to it as His creation" who also may have created "new heavens and new earth for us after death". (Quotation is from The Philosophy of Cosmology, edited by K. Chamcham, J. Silk, J. D. Barrow, and S. Saunders (Cambridge University Press), 2017.) This is not something he said in a pub, but something he wrote in a cosmology book. However, an atheist's belief system also colors HIS science. For example, if the movie "Theory of Everything" is correct, Hawking won some honor for proving that time had a beginning, but then he decided to prove that time did NOT have a beginning (I couldn't find any other reference to this). If this is so, however, possibly the switch was because religious folk seized upon the first proof that God was required to start time and Hawking's new direction is an attempt to refute God. Because the Schwarzschild radius, as I already mentioned, applies in an asymptotically flat spacetime. That does not describe the universe. Well, that flat claim of yours doesn't agree with observation: https://en.wikipedia.org/wiki/Flatness_problem The flatness problem (about which I have written an entire paper) refers to the spatial flatness of the universe on large scales, not to Minkowski space (which is what the black hole is embedded in). You are confusing two different uses of "flat" here. (Again, maybe the moderator can insert some standard explanation here.) [[Mod. note -- There are three distinct concepts involved he (a) *Spacetime* as a whole can be flat, i.e., it's the Minkowski spacetime of special relativity, where the 4-dimensional spacetime Riemann tensor is zero. (b) A spacetime can be *asymptotically flat*, which means that there's a region "far away" where the gravitational field is small. This provides a setting to mathematically formalize such concepts as gravitational radiation, black holes, and measurements of gravitational radiation far away from its sources. (c) A spacetime (which may be non-flat) may be *spatially flat*, i.e., its 3-dimensional t=constant "spatial slices" (roughly speaking, these represent "all of space at a moment in time") may be flat (3-dimensional *spatial* Riemann tensor is zero). Such a spacetime may still have 4-dimensional spacetime curvature. A Venn diagram would show (a) as a single point, and (b) and (c) as partially overlapping regions (whose overlap contains (a)), within the larger region of all spacetimes. In the context of cosmology the universe in which we live is (c) to within experimental error. It is not (a) or (b). However, for astrophysics purposes other than cosmology (e.g., studying black holes and/or gravitational waves emitted by sources other than the big bang itself), it's a very very *very* good approximation to treat the universe as (b). I'll say a bit more about this approximation in a separate posting. -- jt]] Of course, this ASSUMES that the FLRW metric describes our universe. All observations suggest that out universe is well described by the FLRW metric. Doesn't Steinhardt's "theory" also describe it, and without kludging it up with inflation? Since, as Don Page pointed out in the link given above, "We simply do not know whether or not our universe had a beginning." What actually happened at the beginning, if there was one, is a different question. The FLWR metric predicts one, so I think it is quite relevant. My belief system says that it didn't. And I reject the "bounce" model, too. IOW, "big bangs" happen repeatedly without bouncing. In such a universe (multiverse?) curvature is only a "local" phenomenon. Science is not about belief. Au contraire, as I pointed out. It's a historical fact that one becomes married to a viewpoint and only extreme evidence can change that. I'm not saying that's wrong; after all: \_any alternative theory has to explain at least as much as the `standard model' does._/ --- George Efstathiou Steinhardt claims his "theory" does but, heck, I don't know. But in addition: \_Extraordinary claims require extraordinary evidence._/ --- Marcello Truzzi It would seem there is some wiggle room in what the definition of "extraordinary" is, and that is determined by the definer. I think all who ponder the whichness of why, particularly scientists, have two world views. One is the public view (the politically-correct scientist) and his internal world view which maps his personal relationship to the universe. These two world views are probably most nearly congruent in the atheist, but are also most likely to be wrong. The reason for this is that they discount the 13 billion year (and maybe MUCH longer) existence of the universe. Ignoring the "much longer" possibility for now, it appears that the earth and sun were created about 4.5 billion years ago and science posits that intelligent life developed here independently. Our galaxy is twice as old as our sun; indeed, there is a red dwarf a mere 150 light-years away whose metallicity, etc., puts its age at 14 billion years, plus or minus. Anyway, long before our galaxy formed, supernovae had enriched dust clouds with all the chemical species we have today. It is quite unreasonable to assume that in all the universe we are the first. In fact, it is unreasonable to assume that a civilization like ours didn't develop billions of years ago. \_There may be millions of inhabited worlds circling other suns, harboring beings who to us would seem godlike, with civilizations and cultures beyond our wildest dreams._/ -- Arthur C. Clarke Or there may be only ONE. One that has everything organized, or has it all organized in this galaxy, or spiral arm, or ? Anyway, imagine what a civilization a few thousand years beyond ours would be like. It's even harder to imagine one a billion years older. \_we think everything in this universe has to conform to our paradigm of what makes sense. Do you have any idea how arrogant that view is and on how little of this universe we base it?_/ ---Robert Buettner |
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A quasar, too heavy to be true
In article , Gary
Harnagel writes: However, an atheist's belief system also colors HIS science. Why? If one believes that there is no God, because one has no evidence (just as you are very probably an atheist with respect to Zeus and Odin), this doesn't have any effect on one's evidence-based view of the world. For example, if the movie "Theory of Everything" is correct, Certainly not the best way to learn about Hawking's science. His most famous result, that black holes are not completely black, is handled really badly. Hawking won some honor for proving that time had a beginning, The Hawking-Penrose singularity theorems. [[Mod. note -- Just to clarify (the author likely knows this, but others may not)... The hawking-Penrose singularity theorems prove that (given the classical Einstein equations (no quantum mechanics) and certain other assumptions which we think are reasonable) a "trapped surface" must necessarily contain a singularity or singularities. Any astrophysical black hole must necessarily contain a trapped surface. This has very little to do with proving that time had a beginning (in fact, I doubt there is a mathematical proof of this statement), because the universe as a whole is neither a trapped surface nor a black hole. -- jt]] but then he decided to prove that time did NOT have a beginning (I couldn't find any other reference to this). There might not be any. Also, did he "decide to prove" or did some evidence suggest something to him? A scientist cannot just decide to prove something and then prove it. There are at least two restrictions: it has to be provable (which implies that it is true, but not necessarily vice versa) and he has to be capable of proving it. If this is so, however, possibly the switch was because religious folk seized upon the first proof that God was required to start time and Hawking's new direction is an attempt to refute God. Do you have any evidence at all for this? Hawking has been rather clear that he is an atheist, regardless of his belief on whether the universe had a beginning. (Even if it did, this does not in any way imply that a Christian God must exist.) Of course, this ASSUMES that the FLRW metric describes our universe. All observations suggest that out universe is well described by the FLRW metric. Doesn't Steinhardt's "theory" also describe it, and without kludging it up with inflation? Any theory has to agree with the fact that the present universe is well described by the FLRW metric. Since, as Don Page pointed out in the link given above, "We simply do not know whether or not our universe had a beginning." What actually happened at the beginning, if there was one, is a different question. The FLWR metric predicts one, so I think it is quite relevant. Yes, it predicts one (in most cases, including our universe) if the current expansion is naively extrapolated back to a singularity. But a) no-one actually believes that such a singularity exists physically (which is independent of the fact that some theories predict singularities in some cases) and b) no-one yet knows what actually happened in the very early universe. Science is not about belief. Au contraire, as I pointed out. It's a historical fact that one becomes married to a viewpoint and only extreme evidence can change that. Some people do; some people don't. In any case, science is not about belief. Yes, some scientists might be influenced by belief, or money, or fame, or whatever, but this doesn't mean that science is about these things. Science is not whatever scientists do. I think all who ponder the whichness of why, particularly scientists, have two world views. One is the public view (the politically-correct scientist) and his internal world view which maps his personal relationship to the universe. These two world views are probably most nearly congruent in the atheist, but are also most likely to be wrong. The reason for this is that they discount the 13 billion year (and maybe MUCH longer) existence of the universe. Ignoring the "much longer" possibility for now, it appears that the earth and sun were created about 4.5 billion years ago and science posits that intelligent life developed here independently. Our galaxy is twice as old as our sun; indeed, there is a red dwarf a mere 150 light-years away whose metallicity, etc., puts its age at 14 billion years, plus or minus. Anyway, long before our galaxy formed, supernovae had enriched dust clouds with all the chemical species we have today. It is quite unreasonable to assume that in all the universe we are the first. In fact, it is unreasonable to assume that a civilization like ours didn't develop billions of years ago. How does this in any way contradict any worldview? |
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A quasar, too heavy to be true
On 30 Dec 2017, Gary Harnagel wrote:
It is quite unreasonable to assume that in all the universe we are the first. In fact, it is unreasonable to assume that a civilization like ours didn't develop billions of years ago. Ding! Wrong. A first one is a requirement, therefore it cannot be unreasonable to posit it in the absence of knowledge of any other. The odds of spontaneous life could be arbitrarily close to zero. That we are here (necessary for this discussion to take place) has zero commentary on the odds of spontaneous life anywhere else. |
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A quasar, too heavy to be true
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A quasar, too heavy to be true
On 31 Dec 2017, Phillip Helbig wrote:
... Could an intelligent but non-technological species at a level of intelligence similar to humans have arisen sometime in the past but left no fossil or other record? About 40 years ago the "Planetary Report" magazine carried an article about how, about a million years before the dinosaurs vanished, a new human-sized upright-walking dinosaur appeared with stereoscopic vision (I don't have the exact reference, sorry). When reading it, I couldn't help but wonder if they'd built a civilization and then immolated themselves -- that would thus be the true cause of the dinosaurs' disappearance. That may sound absurd, but if we vanished tomorrow, what trace of our civilization would survive 66 million years later? Not a nail. |
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A quasar, too heavy to be true
On Sunday, December 31, 2017 at 5:39:02 AM UTC-7, Phillip Helbig
(undress to reply) wrote: In article , Gary Harnagel writes: However, an atheist's belief system also colors HIS science. Why? If one believes that there is no God, because one has no evidence (just as you are very probably an atheist with respect to Zeus and Odin), this doesn't have any effect on one's evidence-based view of the world. If Odin-worship were a prevalent religious movement and one were an ardent atheist who was miffed by Odin-worship, that might affect his line of inquiry. Scientists are human, too :-) For example, if the movie "Theory of Everything" is correct, Certainly not the best way to learn about Hawking's science. His most famous result, that black holes are not completely black, is handled really badly. I go to more solid sources when they're available. Hawking won some honor for proving that time had a beginning, The Hawking-Penrose singularity theorems. [[Mod. note -- Just to clarify (the author likely knows this, but others may not)... The hawking-Penrose singularity theorems prove that (given the classical Einstein equations (no quantum mechanics) and certain other assumptions which we think are reasonable) a "trapped surface" must necessarily contain a singularity or singularities. Any astrophysical black hole must necessarily contain a trapped surface. This has very little to do with proving that time had a beginning (in fact, I doubt there is a mathematical proof of this statement), because the universe as a whole is neither a trapped surface nor a black hole. -- jt]] It looks like the movie version was wrong there, too. but then he decided to prove that time did NOT have a beginning (I couldn't find any other reference to this). There might not be any. Also, did he "decide to prove" or did some evidence suggest something to him? A scientist cannot just decide to prove something and then prove it. There are at least two restrictions: it has to be provable (which implies that it is true, but not necessarily vice versa) and he has to be capable of proving it. There are theories (or better called hypotheses) already in existence positing that time had no beginning. The oscillating universe, for one. The multiverse one where our universe popped out of it like a bubble is another. Presumably, our universe had a beginning but time existed before that in the one it popped out of. And there are scientists on both sides of the fence on whether they have any existence: https://en.wikipedia.org/wiki/Multiv...s_and_skeptics It seems to me that they have Steinhardt in the wrong camp since his idea has the flavor of a multiverse hypothesis. If this is so, however, possibly the switch was because religious folk seized upon the first proof that God was required to start time and Hawking's new direction is an attempt to refute God. Do you have any evidence at all for this? Hawking has been rather clear that he is an atheist, regardless of his belief on whether the universe had a beginning. (Even if it did, this does not in any way imply that a Christian God must exist.) I agree, but that has nothing to do with what Hawking believes. Of course, this ASSUMES that the FLRW metric describes our universe. All observations suggest that out universe is well described by the FLRW metric. Doesn't Steinhardt's "theory" also describe it, and without kludging it up with inflation? Any theory has to agree with the fact that the present universe is well described by the FLRW metric. Sure. And it has been shown that GR can be derived from quantum theory (with certain assumptions): https://www.youtube.com/watch?v=t9zcBKoFrME http://www.journals.uchicago.edu/doi...10.1086/683448 So, since QED/QFT predicts results closest to reality, it appears that GR is a poorer approximation than a quantum gravity theory would be. For one thing, the graviton is a force particle not unlike the photon or gluon, so the concept of curved (or uncurved, for that matter) spacetime is just a mathematical crutch. (I'm not saying here that crutches are BAD, just that one should keep a place holder for when one gets well). \_spacetime is likely to be an approximate description of something quite different._/ ---Steven Carlip Since, as Don Page pointed out in the link given above, "We simply do not know whether or not our universe had a beginning." What actually happened at the beginning, if there was one, is a different question. The FLWR metric predicts one, so I think it is quite relevant. Yes, it predicts one (in most cases, including our universe) if the current expansion is naively extrapolated back to a singularity. But a) no-one actually believes that such a singularity exists physically (which is independent of the fact that some theories predict singularities in some cases) and b) no-one yet knows what actually happened in the very early universe. Exactly. We'll probably never get to see behind the veil of opacity, which cleared long, long, long after inflation is supposed to have occurred. Science is not about belief. Au contraire, as I pointed out. It's a historical fact that one becomes married to a viewpoint and only extreme evidence can change that. Some people do; some people don't. Those who do change before extreme evidence exists are more often treated as outcasts, crackpots, etc., by the majority. In any case, science is not about belief. Yes, some scientists might be influenced by belief, or money, or fame, or whatever, but this doesn't mean that science is about these things. You are espousing the ideal. Science is not whatever scientists do. No, not "whatever" they do. It IS influenced by what they THINK. I think all who ponder the whichness of why, particularly scientists, have two world views. One is the public view (the politically-correct scientist) and his internal world view which maps his personal relationship to the universe. These two world views are probably most nearly congruent in the atheist, but are also most likely to be wrong. The reason for this is that they discount the 13 billion year (and maybe MUCH longer) existence of the universe. Ignoring the "much longer" possibility for now, it appears that the earth and sun were created about 4.5 billion years ago and science posits that intelligent life developed here independently. Our galaxy is twice as old as our sun; indeed, there is a red dwarf a mere 150 light-years away whose metallicity, etc., puts its age at 14 billion years, plus or minus. Anyway, long before our galaxy formed, supernovae had enriched dust clouds with all the chemical species we have today. It is quite unreasonable to assume that in all the universe we are the first. In fact, it is unreasonable to assume that a civilization like ours didn't develop billions of years ago. How does this in any way contradict any worldview? The existence of a benevolent civilization billions of years older than ours wouldn't change YOUR worldview? Come ON! |
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A quasar, too heavy to be true
On Sunday, December 31, 2017 at 1:48:51 PM UTC-7, Phillip Helbig
(undress to reply) wrote: In article , (Eric Flesch) writes: On 30 Dec 2017, Gary Harnagel wrote: It is quite unreasonable to assume that in all the universe we are the first. In fact, it is unreasonable to assume that a civilization like ours didn't develop billions of years ago. Ding! Wrong. A first one is a requirement, therefore it cannot be unreasonable to posit it in the absence of knowledge of any other. We'll just have to agree to disagree, but see below The odds of spontaneous life could be arbitrarily close to zero. That we are here (necessary for this discussion to take place) has zero commentary on the odds of spontaneous life anywhere else. That's likely to be quite irrelevant: https://en.wikipedia.org/wiki/Panspermia I'm a bit confused. Perhaps you mean that since SOME civilization has to be the first, one can't disregard that we are the first. Whether it is likely that we are the first, and whether it is likely that we are not alone, are other questions. That it is believed life developed here first spontaneously in three or four billion years, yet the universe had the means to initiate the process nine billion years earlier presents the weaker argument. It seems to me that we should be arguing intelligent life developed long ago in the universe until refuted by evidence to the contrary. Opinions vary greatly on the probability of extraterrestrial civilizations. While life might be common, it could very well be that intelligent life is not. For well more than half of the history of life on earth, the most advanced organisms were similar to algae. Since the Cambrian explosion occurred only 600 million years ago, it appears far from inevitable. Similar arguments apply to human civilization, which is very, very recent; if it took so long to arise, it could easily have taken much longer. Until relatively recently, the number of humans on Earth was not that large, and the amount of geological time occupied by humans very small compared to other times. Could an intelligent but non-technological species at a level of intelligence similar to humans have arisen sometime in the past but left no fossil or other record? I'm not considering that; rather, I'm referring to planets around stars that are much older than our sun, say, K-type stars that live as long as the age of the universe. Or maybe, early G-type stars that are gone now but the intelligent species "hatched" by them have migrated to a younger star. At only 0.1% the speed of light, generation ships could cross the entire galaxy in a mere 0.1 billion years. |
#29
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A quasar, too heavy to be true
In article , Gary
Harnagel writes: It is quite unreasonable to assume that in all the universe we are the first. In fact, it is unreasonable to assume that a civilization like ours didn't develop billions of years ago. How does this in any way contradict any worldview? The existence of a benevolent civilization billions of years older than ours wouldn't change YOUR worldview? Come ON! Not in the least. Why should it? I wouldn't be surprised. The Earth is about 4.6 billion years old, the universe about three times as old. Civilization developed here, so I wouldn't be surprised if it did elsewhere, but I don't know how likely it is; perhaps there is some difficult bottlenect. It would be an interesting event, yes, but it wouldn't change my basic worldview. |
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A quasar, too heavy to be true
In article , Gary
Harnagel writes: The odds of spontaneous life could be arbitrarily close to zero. That we are here (necessary for this discussion to take place) has zero commentary on the odds of spontaneous life anywhere else. That's likely to be quite irrelevant: https://en.wikipedia.org/wiki/Panspermia Panspermia is a hypothesis, by no means proven. I'm a bit confused. Perhaps you mean that since SOME civilization has to be the first, one can't disregard that we are the first. Whether it is likely that we are the first, and whether it is likely that we are not alone, are other questions. That it is believed life developed here first spontaneously in three or four billion years, yet the universe had the means to initiate the process nine billion years earlier presents the weaker argument. It seems to me that we should be arguing intelligent life developed long ago in the universe until refuted by evidence to the contrary. Why should we assume anything? Also, there is no way to disprove the existence of extraterrestrial intelligence. Yes, the universe is older than the Earth, but since civilization developed only recently on Earth, it in no way follows that it must have developed earlier elsewhere. I'm not considering that; rather, I'm referring to planets around stars that are much older than our sun, say, K-type stars that live as long as the age of the universe. Or maybe, early G-type stars that are gone now but the intelligent species "hatched" by them have migrated to a younger star. At only 0.1% the speed of light, generation ships could cross the entire galaxy in a mere 0.1 billion years. There is no evidence that this has happened. |
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