Pasha responds: The chemistry of K/Ar decay is easier to understand, so
I'll start with it. The parent rock doesn't have to be pure uranium or pure
potassium. No one claims that. Instead, all we require is something to
reset the age of the rock, such as boiling off all the stable argon. The
argument Temlakos makes that stripping electrons off an element (converting
it to a plasma) somehow transmutes that element or affects its nuclear decay
rate is sheer nonsense, debunked by thousands of experiments. What we know
is that neither heat, cold, pressure, height, depth, principalities, powers,
acids, bases, chemical catalysts of any kind, love, hate, or wishful
thinking has any measurable effect on nuclear decay rates.
Charles P: No one that I know is debating the nuclear decay rates. Uranium
decays very rapidly in a bomb. Uranium decays at a moderate pace in a
nuclear reactor. Uranium decays slowly in rocks.
Pasha responds: Ok. I guess you can call fission "decay". I'll get back to that.
Charles P: I have the CRC Handbook of Chemistry and Physics 86th Edition.
It is MY COPY, so please do not debate that part. Trust me.
CRC Handbook of Chemistry and Physics 86th Edition, section 11, pages
50 to 184
Atomic Number Parent Isotope Natural Abundance in % Half-life in years Atomic
Number Daughter Isotope Natural Abundance in % Half-life in years 92
82 204Pb 1.4000 ***** 92 234U 0.0054 245,500 82 206Pb 24.1000 ***** 92 235U
0.7204 704,000,000 82 207Pb 22.1000 ***** 92 238U 99.2742 4,470,000,000 82
208Pb 52.4000 2.00E+019
90 232Th 100.0000 14,000,000,000 82 208Pb 52.4000 2.00E+019
Charles P: As you stated above, one can heat or cool or whatever to a rock
sample without changing its half-life. That is not a contradiction. The
measurement of half-life of a sample is never made in a bomb nor in a
nuclear reactor. It is measured in a laboratory under laboratory
Pasha responds: Indeed. Actually, I think we may have measured half lives in nuclear reactors. I would be surprised if we had not.
Still, how many natural nuclear warheads have detonated on earth's surface since the beginning of time? A thousand? A hundred? None?
How about none? The ratio of U235 to U238 in a newly sprung supernova is 1.65. That ain't good enough for a squid, mate. You're not going to achieve a critical pile fission pile with ratios so low.
How many natural nuclear reactors have existed on earth's surface since the world began 4.5 billion years ago? We do know of one: Oklo. One. One! Count them. One. We could still do the isotope dating trick with surrounding rock, to show it had not been active for two billion years.
It is possible there have been a tiny handful of other natural nuclear reactors here and there around the world, Charles. However, NONE in the last two billion years.
So, ZERO natural nuclear bombs. If we do isotope dating in Alamagordo, New Mexico, Southern Nevada, Hiroshima, or Nagasaki, we COULD run into some problems. If we do isotope dating without noticing the stacks or domes of nuclear power generation facilities nearby--we're still probably fine. Operators of those places try to exercise care about releasing nasties into the environment. I dare say over 99.999% of the rocks geologists and paleontologists date are more than 10 miles from ANY nuclear power plant or bomb detonation site.
Charles P: To "precisely" and "accurately" date a rock, the scientist must
ASSUME something about the isotopes withing the sample. For example, if
they assume that it is necessary " to reset the age of the rock", then they
will change the sample by doing something "such as boiling off all the
Pasha responds: I think you may be slightly confused here, so I will elaborate in greater detail. Volcanic rock gets hot. Argon escapes. Long afterwards a geologists comes along with a pick or rock hammer and breaks off a sample. This sample gets prepared, where the remaining potassium/argon ratio is examined. And Charles, here is the bonus. If there are other datable isotope ratios in the rock, then the initial value of argon is irrelevant. Instead, isochrons give us the age. You might be surprised how often two or three isotope ratios plot to the same point on a line, over and over again with samples from the same strata. But geologists and paleontologists aren't.
Charles P: Boiling off STABLE argon? Is there such a thing as UNSTABLE
argon? Why can't the scientists leave the sample alone? Would it be
because they might not get "accurate" results?
Pasha responds: Argon is a noble gas. It doesn't readily combine with other elements. In that sense it is stable. I used the adjective to highlight the fact that, if you heat rock containing argon, it doesn't combine with other elements. Instead, it simply escapes. In fact, argon is the third most common element in our atmosphere (1%) after nitrogen and oxygen.
Ok, Charles, how do you measure something? I stick a ruler up against it and take a reading. "Why can't scientists leave the sample alone?" That's just plain funny, man.
No dark sarcasm in the laboratory. Scientists! Leave them samples alone! Hey! Scientists! Leave them samples alone! All in all they're just another rock in the strata.
Doesn't scan quite as well as Pink Floyd.
In astra lumina, Veritas!
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