#21
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WIMPs AWOL Again?
On Aug 23, 3:37*am, eric gisse wrote:
A proton (Hydrogen) is about 0.8 fm, and Uranium is [1] roughly 175,000 fm. So taking 10km as the middle of the neutron star range gives a rough upper limit of...two million kilometers? Using *your* "predicted" (when ---------------------------------------------------------------- Sigh, There is a simple formula for calculating the radii of nuclei. It is: R = (1.3 fermi)(atomic number)^1/3 You can find versions of this approximation in virtually any book on nuclear physics. I have no idea how you can believe a number like 175,000 fm. But there is something seriously wrong with what you say, which is not all that surprising. RLO Fractal Cosmology |
#22
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WIMPs AWOL Again?
In article , "Robert L.
Oldershaw" writes: Have you read Mike Hawkins' preprint: "The case for primordial black holes as dark matter"? I think that he would vigorously disagree with your statement above. Probably. And bear in mind that he is a university professor who actually does scientific research and publishes scientific papers, rather than an amateur. AFAIK, he is not a professor (not that that is really relevant here): http://www.roe.ac.uk/roe/staff/index.html I think it is fair to say that Mike's ideas here are regarded with some scepticism within the community. Of course, there have been many debates within astronomy, with professors on both sides. He had a very good idea, based on observations originally made for something completely different, and it made some testable predictions. One was already confirmed when his first Nature paper on this was published (it was suggested by the referee). However, other predictions have been falsified. It doesn't even look like he could save the appearances by using epicycles, not that that should appeal to you. His work has been discussed here many times, with references. |
#23
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WIMPs AWOL Again?
In article ,
eric gisse wrote: A proton (Hydrogen) is about 0.8 fm, and Uranium is [1] roughly 175,000 fm. That figure for uranium is an orbital radius rather than a nuclear radius - it's half the distance between uranium atoms in a crystal of uranium metal. Uranium nucleus is about 14 femtometres across. Tom |
#24
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WIMPs AWOL Again?
In article , "Robert L.
Oldershaw" writes: On Aug 23, 3:37*am, eric gisse wrote: A proton (Hydrogen) is about 0.8 fm, and Uranium is [1] roughly 175,000 fm. So taking 10km as the middle of the neutron star range gives a rough upper limit of...two million kilometers? Using *your* "predicted" (when ---------------------------------------------------------------- Sigh, There is a simple formula for calculating the radii of nuclei. It is: R = (1.3 fermi)(atomic number)^1/3 You can find versions of this approximation in virtually any book on nuclear physics. I have no idea how you can believe a number like 175,000 fm. I have to agree with Robert here. It looks like Eric quoted a number for a hydrogen NUCLEUS but for a uranium ATOM (possibly ionized). Atoms can be quite large, especially if they are not in the ground state. The formula above shows that the size is given by the number of nucleons, which makes sense only if they are densely packed. (Thus, it should be "atomic weight" rather than "atomic number" above.) The lower limit is obvious. The upper limit is more complicated, but completely well understood within nuclear physics (which is an effective theory and works fine---there are no mysteries---even if the underlying theory is not completely understood). Stars, of whatever type, have a range of sizes also given by physics and also by nuclear physics, however there is no Great Chain of Being which makes this a simple scaling relation. |
#25
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WIMPs AWOL Again?
"Robert L. Oldershaw" wrote in
: On Aug 22, 6:00*pm, eric gisse wrote: Like for example, if one theory predicts dark matter is made of solar mass MACHOs but years of surveys only find some planets that make up a few percentage points, I suppose you would consider that an example of a theory that is fundamentally wrong. ---------------------------------------------------------------------- - ------------------------- Have you read Mike Hawkins' preprint: "The case for primordial black holes as dark matter"? No, Robert. All those times I've quoted it directly and argued against its' contents were just elaborate ruses. Hawkins doesn't even meaningfully address the MACHO surveys. He just wishes and hopes. I think that he would vigorously disagree with your statement above. Because much like yourself, Hawkins has been pushing the same ideas for the past thirty years. I've written about them previously, and the problems are manifold. This is nothing new. Hawkins is wrong. There is an abundance of literature on why Hawkins is wrong. Why Hawkins is wrong has been explained to you before, and doesn't need to be explained for the n+1'th time just because you weren't listening hte previous n times. And bear in mind that he is a university professor who actually does No, he isn't. scientific research and publishes scientific papers, rather than an amateur. I can just imagine the huff and sneer that came after the period. You might consider 0.2 trillion unbound planetary-mass objects trivial, but I think if you had predicted them then you would be singing quite a different tune. Why do I have to keep repeating myself? Even *IF* the amount is correct (and both you and the author of the study question that), the integrated mass value of all those objects is in the neighborhood of a few percent of the entire required mass budget to satisfy what is required. You also predict a ton of objects in the tenths to integer solar mass range, which have happened to evade the last 15 years of MACHO surveys. You have no explanation for this. These surveys, as I have repeatedly given literature citations to, are not incompatible with the discovered planets. But they are - without any doubt - incompatible with theories of dark matter that are based on MACHOs. When you have an actual argument as to how you can have MACHOs being dark matter while escaping all known MACHO surveys then there'll be something to talk about. RLO Fractal Cosmology |
#26
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WIMPs AWOL Again?
On Aug 23, 5:40 pm, Phillip Helbig---undress to reply
He had a very good idea, based on observations originally made for something completely different, and it made some testable predictions. One was already confirmed when his first Nature paper on this was published (it was suggested by the referee). However, other predictions have been falsified. It doesn't even look like he could save the appearances by using epicycles, not that that should appeal to you. His work has been discussed here many times, with references. ----------------------------------------------------------------------------------------- If you have read Mike's most recent preprint, can you make brief, specific, and hopefully more substantive comments on exactly where you think his scientific arguments are weak or appear to be refuted by empirical evidence. Let's confine the discussion to the contents of the specific preprint: http://arxiv.org/abs/1106.3875 . RLO Discrete Scale Relativity |
#27
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WIMPs AWOL Again?
On Aug 23, 5:39*pm, "Robert L. Oldershaw"
wrote: It is: R = (1.3 fermi)(atomic number)^1/3 ------------------------------------------------------------------ Excuse the typo. R = (1.3 fermi)(atomic mass)^1/3 RLO Fractal Cosmology |
#28
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WIMPs AWOL Again?
Phillip Helbig---undress to reply
wrote in : I have to agree with Robert here. It looks like Eric quoted a number for a hydrogen NUCLEUS but for a uranium ATOM (possibly ionized). Correct. I wasn't paying sufficient attention, which then causes me to look like an idiot. On the other hand, I specifically searched for nuclei as opposed to atom (because I know the difference) and the reference says 'nuclei'. Probably should have noticed. [...] |
#29
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WIMPs AWOL Again?
"Robert L. Oldershaw" wrote in
: On Aug 23, 5:40 pm, Phillip Helbig---undress to reply He had a very good idea, based on observations originally made for something completely different, and it made some testable predictions. One was already confirmed when his first Nature paper on this was published (it was suggested by the referee). However, other predictions have been falsified. It doesn't even look like he could save the appearances by using epicycles, not that that should appeal to you. His work has been discussed here many times, with references. ---------------------------------------------------------------------- - ------------------ If you have read Mike's most recent preprint, can you make brief, specific, and hopefully more substantive comments on exactly where you think his scientific arguments are weak or appear to be refuted by empirical evidence. Let's confine the discussion to the contents of the specific preprint: http://arxiv.org/abs/1106.3875 . RLO Discrete Scale Relativity This is an especially aggrivating and stupid aspect of your personality, Robert. I'm rather ****ed off that I didn't immediately remember I went over this with you all the way back in June (All those 3 months ago, aka 'forever ago') you cited arXiv:1106.3875v1; under the theory that MRS Hawkins is an unfamiliar personality to me. Then tell me to 'read it carefully' [1] . Apparently not expecting me to actually do so, or whatever. So being bored of gazing into my navel I take a shot at reading it, and I spot a problem or five. I also remark about how Hawkins' arguments have been chewed up and spat out in the literature rather consistently since I was like three years old. I reply as such. [2] This is where things end, because apparently you decided that you'd post to the thread a few more times then ignore what I wrote. Then you have the raw audacity to ask me whether I've *read the goddamn paper* before? It'd be nice to carry on a technical discussion with you in which you carry your end of the bargain by not running away when I make the effort to bring out technical details. (Normally I would have merely cited the google groups thread, but gg is being a useless heap tonight) [1] http://groups.google.com/group/sci.a...91f1edfb8ec46? dmode=source [2] http://groups.google.com/group/sci.a...44576e1ddcecb? dmode=source |
#30
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WIMPs AWOL Again?
On Aug 23, 3:33*am, Phillip Helbig---undress to reply
wrote: This is a straw-man argument. *Most theories are not theories of everything which unanimously predict everything of interest. *Most theories have some parameters which (as far as we know now) must be determined by observation. *This does not mean that the theory is fundamentally wrong. *For example, many new species of animals and plants are still being discovered. *Our theories of biology are not fundamentally wrong on the grounds that they were not all predicted. *In ------------------------------------------------------------------------------------ Sigh, This is quite beyond the pale, or even the pail. You set up the incorrect statement: A theory should "predict everything". Then you courageously knock down that foolishly absolute argument. The only problem is that I have never said anything like that statement, and you can look through everything I have ever written to verify that I have never said it. I do not deal in such unsophisticated philosophical posturing. It is you who have given us the straw-man argumentation. ---------------------- And, while the original naive steady-state model has safely been put to rest, there are much more sophisticated "steady-state" models that involve oodles of "local" change on every observable Scale, but are globally eternal and statistically unchanging overall. We can do better, RLO http://www3.amherst.edu/~rloldershaw |
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