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Author | Topic: How did the Aborigines get to Australia? | |||||||||||||||||||||||||||||||||||||||||||
Pressie Member Posts: 2103 From: Pretoria, SA Joined: |
quote:They (in all honesty, I think) are convinced that it's "science". Scoffers, like you, were predicted in the Bible. Remember, "science" explains exactly how Aboriginees got to Australia: Goddidit. Edited by Pressie, : Added sentence
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saab93f Member (Idle past 1422 days) Posts: 265 From: Finland Joined:
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Although this reply is veering slighly offtopic...I have never understood how cretins (xians mostly) are claiming to be morally superior to us minnows of satan, they see no problem in outright lying to suit their agenda. I believe I am not very wrong when I claim that creationism is based on ignorance and stupidity and all it produces is hypocrisy, distortion of truth and more ignorance.
This applies well in this topic as well - when no fact suits their claims then in comes distortion of known facts. Wallabies have never traveled from Australia to Turkey and back, period.
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Portillo Member (Idle past 4188 days) Posts: 258 Joined:
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quote: Thats the end of that debate then. Thanks for clearing that up. Sorry to hear that Christians make your heart burn with rage. And the conspiracy was strong, for the people increased continually - 2 Samuel 15:12
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Pressie Member Posts: 2103 From: Pretoria, SA Joined: |
quote:My experience with religious people (I used to be one, too), is different. The one’s I have met and still meet certainly don’t think they are morally superior to me and most of them also acknowledge that they don’t get all their moral values from the Bible. I have to add that I usually refer to the very unpleasant verses in the Bible they never heard about before. They don’t have enough knowledge about it to try apologetics. On the net I see all these real fundies and funnies. In real life, I don’t normally. The only fundie I listened to in my church set me off on the path of atheism. The ones I meet just believe their Ministers, Vicars, Priests, or whatever. The Muslims I meet are exactly the same. No fundamentalism around. (Well, I work in a Scientific Institution). Even all the the Muslims I meet accept an old earth and the Theory of Evolution, too. quote:All creation scientists have to tell porkies. The people who quote those scientists on the internet also have to tell porkies. That’s all they have. quote:You’re 100% correct on that one. That’s all they have. quote:Geography and evolution tied that Wallaby down. It doesn’t matter how many times creation scientists invoke wishful thinking and magic. Wishful thinking does not change facts. Edited by Pressie, : Changed the words "lie" and "lied" to tell porkies to avoid those stars. Edited by Pressie, : No reason given.
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Pressie Member Posts: 2103 From: Pretoria, SA Joined: |
quote:The debate ended a long time ago. Creationists should stop telling porkies before there can be any meaningful debate with them on anything.
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Portillo Member (Idle past 4188 days) Posts: 258 Joined: |
Then they should close down the forum or at least rename it to evolution forum.
Edited by Portillo, : No reason given.And the conspiracy was strong, for the people increased continually - 2 Samuel 15:12
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Larni Member Posts: 4000 From: Liverpool Joined:
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Or call it Science vs Magic.
The above ontological example models the zero premise to BB theory. It does so by applying the relative uniformity assumption that the alleged zero event eventually ontologically progressed from the compressed alleged sub-microscopic chaos to bloom/expand into all of the present observable order, more than it models the Biblical record evidence for the existence of Jehovah, the maximal Biblical god designer. -Attributed to Buzsaw Message 53 Moreover that view is a blatantly anti-relativistic one. I'm rather inclined to think that space being relative to time and time relative to location should make such a naive hankering to pin-point an ultimate origin of anything, an aspiration that is not even wrong. Well, Larni, let's say I much better know what I don't want to say than how exactly say what I do.
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Portillo Member (Idle past 4188 days) Posts: 258 Joined: |
Evolution vs Divine Intervention.
Edited by Portillo, : No reason given.And the conspiracy was strong, for the people increased continually - 2 Samuel 15:12
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Granny Magda Member Posts: 2462 From: UK Joined: Member Rating: 3.8
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Thats the end of that debate then. Thanks for clearing that up. I can sympathise with you on that score, but the truth of the matter is that the debate amongst scientists has ended. All of the things we've touched on in this thread - evolution, common ancestry, human and animal migration, plate tectonics - they've been an accepted part of the scientific consensus for a long time now. The scientific controversy is over, bar a tiny handful of religiously motivated stuck-in-the-muds who stubbornly hang onto creationism. The problem is that public opinion (especially in the US) hasn't caught up. Amongst the public, there are still significant numbers who favour some sort of creationism, ranging from full-on Biblical (or Koranic) literalism to theistic evolution. The position of actual scientists is often not well understood. This is compounded by the nasty habit of creationists to meddle in matters of science education. The bottom line is that the public controversy will continue until the public finally catch up and get in line with what the experts are telling us. This forum is very much aimed at that public debate, rather than any kind of professional audience. By the way, how do you feel about the model for marsupial evolution and migration that has been presented so far? Do you still have problems with it? If so, what is troubling you? Mutate and Survive Edited by Granny Magda, : No reason given. Edited by Granny Magda, : No reason given.
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caffeine Member (Idle past 1052 days) Posts: 1800 From: Prague, Czech Republic Joined: |
If you wish to suggest that the Australian fauna crossed a land bridge from Asia to Australia after the flood, then you have to explain (a) why no placental mammals went with them Just a small correction, but some placentals did go to Australia. Whilst there are no big placentals knocking about, Australia has a rich collection of native rodents and bats. Collectively, they make up more than a quarter of the species of native Australian mammal.
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Dr Adequate Member (Idle past 312 days) Posts: 16113 Joined: |
Just a small correction, but some placentals did go to Australia. Whilst there are no big placentals knocking about, Australia has a rich collection of native rodents and bats. Collectively, they make up more than a quarter of the species of native Australian mammal. I was aware of the bats, but presumed that they flew, rather than crossing a land bridge; I was also aware of the rodents, but had the impression that they were all descendants of hitch-hikers, in which I now think myself to be wrong.
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RAZD Member (Idle past 1432 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi again NoNukes,
Enrichment means the ratio of fissile to non-fissile material. No, enrichment means changing the ratio of fissile to non-fissile material to increase the proportion that is fissile compared to the proportion that is non-fissile. This increases the density of the fissile material within the combined mass.
That is not right. And it is not what your reference says. First, fission is not decay. Fission in a critical or super-critical reactor is generated primarily by the absorption of thermal (slow) neutrons by fissile material. Only the tiniest amount of neutrons are produced by spontaneous fission, which might be considered similar to decay. As long as the spontaneous fission rate is non-zero, and the geometry and enrichment are correct, then induced fission can occur and will dominate. Do you think that fission is a completely separate process from decay? That they operate under different physical laws? Fission is just a form of decay: instead of alpha and beta particles, larger chunks are involved. What is the difference in the process between fissioning off a Helium nucleus (alpha particle) and a larger nucleus? What causes the neutron emission? Neutron emission - Wikipedia
quote: Curiously, beta decay leaves behind an extra neutron.
quote: Fission is a type of decay process. Spontaneous fission - Wikipedia
quote: The process that results in alpha and beta decay is the same process for spontaneous breakdown into nuclei larger than a Helium nuclei (alpha particle). You can't affect decay rates without affecting fission decay. When you reduce the nuclear binding energy or lower the barrier for radioactive decay to occur, and reduce the decay rate, you would increase the occurrence of all forms of radioactive decay, including fission. This means that the critical mass required to reach a sustained reaction is reduced.
As an analogy, consider that spontaneous fission, which can be likened to decay and might increase when the decay rate increases, is only the fuse for the chain reaction. It doesn't matter much how bright is the match that lights the fuse. Here is how a chain reaction is produced in a natural or man made reactor. Some amount of spontaneous fission occurs, spontaneously producing neutrons fast neutrons. Each fission of U235, for example, produces 2.4+ fast neutrons. But only some of those neutrons in turn are slowed and cause fission. Depending on geometry, enrichment, the amount of neutron absorbing materials like carbon and hafnium, thermalizing material, and some other variables, only some of those neutrons get slowed down to thermal speed, and then engage new U235 nuclei causing fission. ... And to complete your analogy, now consider applying a match to wet newspaper and newspaper dowsed in gasoline. The level of enrichment needed to reach the point where the fission process becomes continuous or explosive is reduced, the amount of fissionable material to reach critical mass is reduced. Enjoy.by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)
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NoNukes Inactive Member |
Zen Deist writes: No, enrichment means changing the ratio of fissile to non-fissile material to increase the proportion that is fissile compared to the proportion that is non-fissile. Enrichment is a noun. Enriching would have the meaning you give. A proper usage of the word enrichment is the ratio of fissile to non-fissile material as enrichment. Here is an example: Enriched uranium - Wikipedia
quote: I'll mention in passing that I have operated nuclear reactors for a living and that I'm not guessing about this. I apologize for my initial weak statement that suggested I only believed you are wrong. I know that you are wrong.
Fission is just a form of decay: instead of alpha and beta particles, larger chunks are involved. What is the difference in the process between fissioning off a Helium nucleus (alpha particle) and a larger nucleus? Spontaneous fission is a form of decay. I have already acknowledged that. Induced fission is NOT a form of decay. Induced fission is caused by the absorption of a neutron by a fissile nucleus resulting in an excited nucleus and a rather speedy fission. Induced fission is required for a chain reaction. Spontaneous fission alone cannot produce a chain reaction although it may be possible to create a significant amount of energy from spontaneous fission. In contrast, decay is not induced and has no real cause.
This means that the critical mass required to reach a sustained reaction is reduced. No it does not mean that. Let me approach this question in a different way. Doubling the spontaneous fission rate does NOT produce the same effect as doubling the enrichment. While in both cases you will double the number of source (spontaneous) neutrons generated in a given mass, doubling the spontaneous fission rate does not double the number of U235 targets for those neutrons. On the other hand doubling the enrichment will quite obviously have that effect in addition to doubling the number of neutrons flying around. When the spontaneous fission rate is doubled, approximately the same percentage of source neutrons will cause induced fission as before. As long as that percentage remains below 42%, no chain reaction can be produced. That means that the mass is still not critical.
Curiously, beta decay leaves behind an extra neutron. A neutron which remains in the nucleus in most cases. There are some cases where a free neutron can be produced from a beta decay product (neutron precursors) produced by a fission. Edited by NoNukes, : No reason given. Edited by NoNukes, : Edit discussion of neutron precursors. Edited by NoNukes, : No reason given.Under a government which imprisons any unjustly, the true place for a just man is also in prison. The proper place to-day, the only place which Massachusetts has provided for her freer and less desponding spirits, is in her prisons, to be put out and locked out of the State by her own act, as they have already put themselves out by their principles. Thoreau: Civil Disobedience (1846)
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foreveryoung Member (Idle past 610 days) Posts: 921 Joined: |
Very simply put, if you change the decay rate, you change the decay energy, and the diameter of the halo changes. wikipedia writes: The decay energy is the energy released by a radioactive decay. If the decay energy is the energy releassed by a "single" radioactive decay, why would the timing of those decays have any effect of the energy of any one decay?
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RAZD Member (Idle past 1432 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi NoNukes,
First off, I am aware that you have worked in a nuclear reactor. That does not mean that you have worked through the question of what you need to do to increase the rate of decay, and then determined how that affects the rest of the (atomic) world.
Enrichment is a noun. Enriching would have the meaning you give. Enrichment Definition & Meaning | Dictionary.com
quote: Fine. I was using action while you are using state, but we can use enriching for clarity to reduce confusion. The point is the same.
Spontaneous fission is a form of decay. I have already acknowledged that. Induced fission is NOT a form of decay. Induced fission is caused by the absorption of a neutron by a fissile nucleus resulting in an excited nucleus and a rather speedy fission. Induced fission is required for a chain reaction. Spontaneous fission alone cannot produce a chain reaction although it may be possible to create a significant amount of energy from spontaneous fission. Curiously, the natural reactors at Oklo were started by spontaneous fission. The relative proportions (natural state of enrichment) today do not allow this, but they did in the past: http://oklo.curtin.edu.au/what.cfm
quote: The natural level of enrichment in the ore 2000 million years ago was the same as your man-made enriched uranium used in nuclear reactors today. The processes that are documented in the evidence left at Oklo show that they underwent fission similar to reactors today, with no change of the physical laws governing the behavior of radioactive elements from then to now.
Doubling the spontaneous fission rate does NOT produce the same effect as doubling the enrichment. While in both cases you will double the number of source (spontaneous) neutrons generated in a given mass, doubling the spontaneous fission rate does not double the number of U235 targets for those neutrons. On the other hand doubling the enrichment will quite obviously have that effect in addition to doubling the number of neutrons flying around. It does not double the number of targets, but it does double the number of bullets, thus doubling the exposure of the targets, with the effect being the same as doubling the enrichment in material today. This would also be akin to providing a neutron reflector around the material. http://nuclearweaponarchive.org/Library/Fission.html
quote: In nuclear reactions today some neutrons are lost from the chain reaction due to neutron capture without fission, due to the binding energy level of the various isotopes. Curiously, the binding energy also affects the decay rate, and increased decay rate means that the effective binding energy of the atom\isotope is reduced. With lower binding energy, neutron capture is more likely to exceed the (lower) binding energy limit for fission to occur, with the result that induced fission would occur more often: less critical mass is needed. In addition, the numbers of neutrons resulting from fission would also increase:
quote: Amusingly, neutrons exist in integer quantities, not fractions. There is variation in the number of neutrons produced from individual events. The number of neutrons produced is also related to the binding energy that controls decay rates. Faster decay = more neutrons produced by induced fission = less critical mass. Enjoyby our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)
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