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Author Topic:   How did the Aborigines get to Australia?
NoNukes
Inactive Member


(2)
Message 6 of 226 (645809)
12-30-2011 9:28 AM


Forget about the boats?
While the boat comment is misguided, it does turn out that kangaroos are really good swimmers. Perhaps an argument might be made that kangaroos could have island hopped their way onto an island that is merely a really arduous swimming distance away from Australia.
Portillio seems to be addressing the question of how kangaroos got to the ark, and then returned to Australia after the great flood was over. I'm not sure I find his answer satisfactory, or why he bothers. Surely God could have overcome whatever difficulties faced the kangaroos.
But as has already been pointed out, the question people ask about kangaroos is a considerably different from the question as phrased by Portillio. We know that man migrated to Australia, but we also see that man is present in every single location between Egypt and Australia. On the other hand, there don't seem to be any kangaroos in the Middle East, while there is evidence of kangaroos evolving in Australia.

  
NoNukes
Inactive Member


Message 12 of 226 (645828)
12-30-2011 2:03 PM
Reply to: Message 10 by nwr
12-30-2011 9:59 AM


nwr writes:
For that matter, it is pretty much impossible for an Australian to believe that the Australian aborigines are descendents of Adam.
Could you expand on this proposition a bit? Is there some reason to believe that aborigines do not have a common origin with the rest of us?

This message is a reply to:
 Message 10 by nwr, posted 12-30-2011 9:59 AM nwr has replied

Replies to this message:
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NoNukes
Inactive Member


(1)
Message 17 of 226 (645856)
12-30-2011 5:21 PM
Reply to: Message 14 by Trixie
12-30-2011 2:18 PM


Re: About boats...
As long as we're dolling out accolades, let's give OP and Percy some of the credit for pitching that meatball to the Babe.

This message is a reply to:
 Message 14 by Trixie, posted 12-30-2011 2:18 PM Trixie has not replied

  
NoNukes
Inactive Member


Message 42 of 226 (646152)
01-03-2012 12:57 PM
Reply to: Message 40 by RAZD
01-03-2012 8:48 AM


Re: rapid decay knock-down
It also means that there would have been a large number of spontaneous natural reactors wherever uranium and other fissionable isotopes were found in the concentrations seen in the earth today:
I don't think this is correct.
Your post seems to confuse decay with fission. Speeding up decay does not necessarily mean creating a critical or super-critical natural reactor. In fact, producing a self sustaining fission reaction does not follow from having sped up nuclear processes.
What is required is that each neutrons produced by a fission reaction on average produce at least one new neutron from fission. This depends more on the physical arrangement and enrichment of the fissile material, and to a first order is independent of the rate at which absorbing a neutron causes an atom to split.

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)

This message is a reply to:
 Message 40 by RAZD, posted 01-03-2012 8:48 AM RAZD has replied

Replies to this message:
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NoNukes
Inactive Member


(1)
Message 44 of 226 (646280)
01-03-2012 11:56 PM
Reply to: Message 43 by RAZD
01-03-2012 6:03 PM


Re: rapid decay knock-down
Zen Deist writes:
Curiously, critical mass is defined by the number of decay events within a given volume of radioactive material.
Really. So why does your quote lists the variables that I mentioned? It does not support your position at all.
quote:
the mass where criticality occurs may be changed by modifying certain attributes such as fuel, shape, temperature, density and the installation of a neutron-reflective substance.
Enrichment and geometry. Just as I said. The purpose of the neutron reflective material, which I did not mention, is to return neutrons that escape the mass back to the fissile material. I would lump that in with geometry. Again, this supports my position.
Enrichment means increasing the density of decaying material.
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.
Enrichment means the ratio of fissile to non-fissile material.
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. For at more complete description of the neutron life cycle see the wikipedia article on the six factor formula.
Six factor formula - Wikipedia
As long as about 42 percent or more of those 2.4+ neutrons in turn produce induced fissions of U235, then an upward ramping chain reaction is produced. It scarcely matters exactly what the the reaction rate of spontaneous fission rate is, because of the multiplying effect caused by the chain reaction, at least approximately so.
What does matter is how many neutrons escape or or absorbed without producing fission. And that depends primarily on geometry and enrichment. Not on the decay rate.
ABE: by "how many", I mean how many escape or are absorbed as a percentage of those neutrons produced. Doubling the spontaneously produced neutrons doubles the number of neutrons that escape, thus maintaining a non-critical neutron life cycle.
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)

This message is a reply to:
 Message 43 by RAZD, posted 01-03-2012 6:03 PM RAZD has replied

Replies to this message:
 Message 57 by RAZD, posted 01-07-2012 1:25 PM NoNukes has replied

  
NoNukes
Inactive Member


Message 58 of 226 (646966)
01-07-2012 2:59 PM
Reply to: Message 57 by RAZD
01-07-2012 1:25 PM


Re: rapid decay knock-down
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:
Later US nuclear weapons usually use plutonium-239 in the primary stage, but the secondary stage which is compressed by the primary nuclear explosion often uses HEU with enrichment between 40% and 80%[6] along with the fusion fuel lithium deuteride.
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)

This message is a reply to:
 Message 57 by RAZD, posted 01-07-2012 1:25 PM RAZD has replied

Replies to this message:
 Message 60 by RAZD, posted 01-07-2012 9:13 PM NoNukes has replied

  
NoNukes
Inactive Member


Message 63 of 226 (647066)
01-08-2012 1:00 AM
Reply to: Message 60 by RAZD
01-07-2012 9:13 PM


Re: rapid decay knock-down
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.
Not so fast with the dictionary. I didn't stop with the noun/verb issue. That would have been pedantic. I also provided, from the same reference that you are using, evidence that enrichment is also used to refer to the degree of the enrichment of fissile material and not merely as the name of the process or state.
What did you think the wikipedia article meant when it referred to an enrichment of 80 percent? Is it your opinion that such usage is incorrect?
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.
Are you claiming to have done so? I'm going to return to this question at the end. I'll just note here that I don't see that you have actually made an argument that addresses this point. Instead you have asserted effects that result directly from an increased fission rate. And some of those assertions are demonstrably wrong. I'll deal with those first.
I am in fact familiar with the factors that are required to allow a sustained chain reaction, and your posts suggest that you are not. Increasing the number of source neutrons alone without increasing the percentage of those neutrons that cause fission will not result in criticality. In fact the lack of a suitable source of neutrons for starting a chain reaction is a problem that we dealt with occasionally when the submarine's reactor had been shut down for a considerable period.
Curiously, the natural reactors at Oklo were started by spontaneous fission.
Started, yes. I've already acknowledged that some source of neutrons is required to start the chain reaction and that neutrons from spontaneous fission are candidates for doing so.
But the starting of the Oklo reactor required something more than a ource of neutrons. Some action must have occurred such as adding a water moderator, or concentrating the uranium, or changing the shape of the "vessel" in which the uranium is contained. In other words by some change that actually affected keff so that it became > 1. The wikipedia article describes some possible scenarios.
Your argument regarding the natural state of enrichment does not rebut my argument in any way. Nor does the observation that natural reactors can no longer occur. As your source indicates, the reason that they can no longer occur is because of the ever decreasing amount of U235 relative to U238. That point is completely consistent with my argument as well as yours. But other factors suggest that I am correct.
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.
I'll make two points regarding the above
First, increasing spontaneous fission is not akin to providing a reflector. A reflector allows some of those neutrons that escape the mass of uranium to have a second chance at creating fission. Increasing the number of source neutrons alone does not increase the chance that any one of those neutrons induces fission.
Further, simply increasing the generation rate of source neutrons won't decrease the percentage of neutrons that get absorbed in materials other than uranium, and would not necessarily decrease the percentage of neutrons that escape the mass of uranium.
Secondly, you are ignoring half of the argument that I made. Increasing enrichment increases both bullets and targets, while increasing the decay rate simply increases the bullets. I think it should be quite obvious that those two situations do not produce the same result. That should at least open up the possibility that increasing enrichment will increase keff (see six factor formula) while increasing the decay rate might not.
But let's address your questioning of whether I have considered what other reactions might increase if the decay rate is increased. I think this is a valid point.
The mechanism for increasing the decay rate has not been specified. At this point the mechanism is PFM (pure freaking magic). I think it is reasonable (but perhaps not inevitable) that the mechanism will increase spontaneous fission in the same way it increases U238 decay rates, exactly as you have proposed, and I have assumed that such a thing will happen.
But I don't think it is reasonable that the same PFM would inevitably change things such as the relative rates of absorption of neutrons in uranium vs. other materials, the rate at which neutrons are slowed down by a moderator such as water, or the probability that a neutron in the vicinity of a U235 atom actually gets absorbed. So absent a mechanism, I don't see how you can conclude that increasing the decay rate will inevitably produce a critical geometry.
I think our disagreement results from your belief that enrichment enables criticality by increasing the number of spontaneously generated neutrons. My position is that enrichment enables criticality primarily by increasing the number of targets available for each generated neutron.
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)

This message is a reply to:
 Message 60 by RAZD, posted 01-07-2012 9:13 PM RAZD has replied

Replies to this message:
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NoNukes
Inactive Member


Message 94 of 226 (648310)
01-14-2012 12:08 PM
Reply to: Message 93 by Percy
01-14-2012 8:45 AM


Re: Chuck's CMI Lies
Right, but at least Chuck wasn't throwing out some fanciful idea relying on magic. There is such a thing as land bridges. Land bridges do exist.
Yes. And there are also such things as tsunamis and sandbars.
Chuck77 does not need evidence because for him, what is important is that scientific evidence that the flood did not happen exactly according to his interpretation of Genesis does not constitute iron clad proof that the Bible is wrong.
So any proposed scenario for anything that might have happened in the Bible, that cannot be ruled out with 100% certainty, particularly if the scenario does not even require the supernatural, serves the same purpose as for a creationist, that real, and convincing evidence serves for non-Biblical propositions.
Science has evidence but not absolute certainty about the flood, which of course is as nothing compared to the Word of God, and Chuck77 believes that the Word says that the earth was flooded about 4500 years ago. And Chuck77 is not going to agree to any proposition that costs him eternal life. Few would.

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)

This message is a reply to:
 Message 93 by Percy, posted 01-14-2012 8:45 AM Percy has replied

Replies to this message:
 Message 95 by Percy, posted 01-14-2012 12:39 PM NoNukes has replied

  
NoNukes
Inactive Member


Message 96 of 226 (648321)
01-14-2012 1:19 PM
Reply to: Message 95 by Percy
01-14-2012 12:39 PM


Re: Chuck's CMI Lies
All true. I'm beginning to appreciate slevesque a bit more. Where is that dude?

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)

This message is a reply to:
 Message 95 by Percy, posted 01-14-2012 12:39 PM Percy has seen this message but not replied

  
NoNukes
Inactive Member


Message 183 of 226 (671984)
09-01-2012 10:52 AM
Reply to: Message 182 by Portillo
09-01-2012 2:34 AM


Re: Dates, evidence, and opinions, round 2
Isnt that what you were asking? If the Bible says that the mountains rose and the basins sank down?
The question is whether the statement is made in connection with Noah's flood events. Everything else in Psalm 104:1-25 seems to be about creation. I understand that Hovind and Ham think otherwise, but most commentary I can find indicates that these two are out to lunch.
One example:
http://www.godandscience.org/...h/psalm104.html#.UEIgZcGPWDE
quote:
There are a number of figures of speech used in Psalm 104 that clearly refer to the original creation as opposed to the flood. The reference to the boundaries of the deep are a clear reference to the original creation (Proverbs 8:29, Psalm 33:6-7, Jeremiah 5:22, and Job 38:8-11). There are no references to "boundaries" in any of the flood references. A second figure of speech is the idea of the earth being covered by a garment, which is only found in the creation passages, and never in the flood passages (Proverbs 30:4, Job 38:9). In addition, there are no references to the mountains rising and the valleys sinking (Psalm 104:8) after the flood, although these events could be clearly linked to the setting of the boundaries of the sea as described in Genesis 1 and Job 38.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison.
Choose silence of all virtues, for by it you hear other men's imperfections, and conceal your own. George Bernard Shaw

This message is a reply to:
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NoNukes
Inactive Member


Message 207 of 226 (672646)
09-10-2012 11:28 AM
Reply to: Message 205 by Panda
09-10-2012 8:41 AM


Re: Dates, evidence, and opinions, round 2
It seems that Portillo may also think that fossilization is simply animals being encased.
This is a results driven answer. Fossils are supposed to be evidence of the Noahic flood. So they must result from a sudden catastrophe. There is no science and no explanatory model. Catastrophic entombment must be so.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison.
Choose silence of all virtues, for by it you hear other men's imperfections, and conceal your own. George Bernard Shaw

This message is a reply to:
 Message 205 by Panda, posted 09-10-2012 8:41 AM Panda has seen this message but not replied

Replies to this message:
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NoNukes
Inactive Member


Message 226 of 226 (692527)
03-04-2013 1:13 PM
Reply to: Message 221 by dwise1
03-03-2013 10:58 AM


Re: Dates, evidence, and opinions, round 2
Mr. Beans seems a lot more jovial than Portillo ever was. If CoolBeans is a sock puppet, he's one I don't mind having here.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison.
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass

This message is a reply to:
 Message 221 by dwise1, posted 03-03-2013 10:58 AM dwise1 has not replied

  
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