On Fri Mar 24 2000 (22:20:28 EST) Allen Roy writes:
>From: Steven M. Smith <smsmith@helios.cr.usgs.gov>
[Snips]
>> This is at least the second time that I have seen you make this argument for
>> circular reasoning in age dating. In a sense, you are correct. I assume
>> "that the rocks are old enough to be dated." I also assume that my
>> 14-yr-old daughter is old enough to be dated ... in the sense that we can
>> assign an age to her. The point is that assuming an object is old enough
>> for its age to be determined doesn't invalidate the measured age. All I
>> need is the right method.
>
>There is a major flaw in your analogy. You know the age of your daughter,
>you don't know the age of a rock.
Allen,
Let's assume that I don't know her age. (My wife and daughter have no
trouble believing that!)
>Let me illustrate, Let's say I drop by your place, having never seen a child
>before, and I decide to determine her age. So, everyday for a month I
>measure her height. I discover that she grew from 1.366 meters (4' 5 3/4")
>to 1.370 meters (4' 5 7/8). By extrapolation into the past (to zero, I said
>I knew nothing of children. :) I find that she is 28.54 years old. You look
>at me like I am crazy, because you were there from start to finish and you
>know she is only 13 year old. But I have absolute empirical evidence that a
>child grows 0.004 meters per month!
I realize that this is an analogy but it is a very poor characterization of
the scientific process ... or else you have a very low opinion of
scientists if you believe that this represents the type of thought behind
radioactive dating methods.
There is nothing wrong with your hypothesis, but your experimental process
was insufficient to either confirm or refute it. To test this idea of age
being proportional to height, you wouldn't measure just one child for a
month but several. Even if the experiment was limited to just one month,
you would then quickly find that a simple straight-line age determination
method is inappropriate. In fact, I predict that you would find a rough
pattern of increased growth rates with shorter height - perhaps suggesting
a logarithmic pattern of growth vs age. However, there probably would
be enough variation between height and growth rates to make you doubt your
hypothesis. Now if your lifetime were too short to finish observing and
measuring the entire growth and aging process for a single child, you could
still measure and determine growth patterns for several creatures with much
shorter life spans. If you found significant variation in growth patterns
for different creatures or within a species then your "growth measures age"
hypothesis would be in serious trouble. The point is that it takes more
than a few simple measurements to establish a growth curve worthy of
extrapolating.
But let's assume your research revealed that the growth pattern of EVERY
single species ever measured EXACTLY followed the same logarithmic curve.
In addition, for every separate species of creature measured the rate at
which the growth followed that curve could be assigned as an invariable
constant in the formula of that logarithmic curve. If this were always the
case, then given the height of any creature and the measured constant, one
could determine the age of that creature - within the limits of our
measuring techniques.
This is the case for radioactive decay rates. There are hundreds of
radioactive isotopes. The majority of them have decay rates that are well
within the normal lifespan of a single person. From thousands of
measurements done by different scientists in different laboratories all
over the world, we know that populations of every single isotope ever
measured follows the exact same logarithmic decay curve and that the rate
of decay for a population of each separate isotope can be expressed as a
constant value or half-life. Multiple measurements have determined and
confirmed these half-life constants.
This measurement of decay rates was begun by physicists (not geologists)
before anyone tried to use the method to date rocks. For the most part,
these physicists couldn't have cared less what age geologists wanted for
their rocks. If the method determined that radiometric ages for the
oldest rocks were consistently 1 B.Y., 1 M.Y., or 10,000 years, then in
their opinion, geologists would have to accept it. Likewise, as a
geologist, I could care less how much time biologists need for evolution
to occur. If I could prove that a rock containing fossils of modern
homo sapiens was 500 M.Y. old, or a dinosaur-bearing fossil bed was
6,000 years old, they would have to live with the results.
------
[More Snipping - I apologize but I simply don't have the time to respond
to every point in your post.]
------
>My assumption above was that it was possible to measure height and estimate
>age. Wrong! The problem with radiometric dating is the assumption that it is
>possible to measure quantities of isotopes and estimate age.
>
>I also had to assume in my estimation that the child could really be as old
>as I calculated for me to accept it as valid. You have to assume that the
>rocks can really be as old as your calculations for those ages to be valid.
My assumption is not so much that the rocks can or cannot be as old as
radiometric methods imply but simply that studying and measuring the part
of the Universe with which we are familiar is a valid method for
understanding it. From the empirical evidences and the progress which I
see in following this assumption, I also assume that we are capable of
deriving a limited understanding of the properties which describe how the
Universe works. Some of these properties are referred to as the "Laws of
Science."
>You don't accept my estimation because you know the child is not that old
>and therefor you know my assumptions are incorrect. I don't accept
>radiometric dating because I know from someone who is in the position to
>know and who has told us so that the rocks (sedimentary rocks in particular)
>are not that old and therefore I know that the assumptions behind
>radiometric dating are in error.
Please share with us where God has said that "the rocks (sedimentary rocks
in particular) are not that old." This passage must be missing in every
translation of the Bible which I have. All translations of the Bible that
I have read say absolutely nothing about sedimentary rocks being 4,000
years old (or 6,000 or 10,000 years old). By adding up some genealogies
and making some assumptions about the timeframes of certain patriarchs we
can get a possible age for Noah's Flood at about 4,000 years ago BUT
nowhere in the flood story can I find any mention of sedimentary rocks or
gravel, pebbles, sand, silt, clay, or mud. All it says is that the water
covered the earth. The amount of sediment deposited by this event is not
mentioned and must be an assumption on your part.
>But, you say, God has not told us anything about the age of the rocks. The
>Bible is mythology especially Genesis. The writers of the Bible did not
>understand science and so they do not qualify as valid observers.
[More Snippage - As I said in the first post, I'll leave the discussion of
Evolutionary Creationist's motives, theology, etc for someone else or
another time. As much as possible, I prefer to deal with one problem at a
time. Probably an impossible task but I try.]
>> With the exceptions noted in my first post (and David Bowman's
>> correction of my sunlight/cosmic ray blunder), why are there no
>> naturally-occurring radioactive isotopes having half-lives of 70
>> million or less? This question is valid whether all Sm-146 (70 M.Y.
>> half life) has decayed or whether it has simply decayed to the
>> point that we can no longer detect it. Note that a 4.55 B.Y. old
>> Earth would be 65 half lives for Sm-146 or 1 atom left for every
>> 37*10^18 original atoms.
>
>This is another topic, only partially related to the age of the rocks by
>which the sedimentary rocks are dated which we have been discussing. As I
>have stated before I am a Creationary Catastrophist, i.e. I believe that the
>Creation Week occurred somewhere in the 6000 to 10000 year ago range and
>that there was a global catastrophe responsible for all (or nearly all)
>sedimentary rocks some 4000 years ago. However, unlike many of my
>Creationary Catastrophist friends, I am not a YEC. I believe that there is
>non-symbolic Biblical evidence that the universe (including this planet and
>solar system) could be very old. (The Biblical basis for this is another
>topic too long to be discussed at this moment). Therefor, that the
>foundational rocks might be depleted in certain isotopes is not a problem
>for me. It is a problem for my YEC friends and they have proposed various
>theories to try to explain away the problem. However, I do not find those
>theories convincing nor necessary.
Having read some of your former posts over the past few years, I was aware
of your Old Universe-Young Creation Week view. That's why I'm confused
about your argument of circular reasoning wrt radioactive decay age
determination methods. You appear to accept the depletion of certain
radioactive isotopes as evidence of long periods of time implying that
radioactive decay laws are valid and also that the Universe has a history
that is "old enough to be dated"; and yet you don't accept that those same
radioactive decay laws are valid when applied to understanding the history
of the Earth's crust and when they imply that those fossil-bearing
sedimentary rocks are also "old enough to be dated." It sounds like you
want to pick and choose only those parts of science that you like and then
reject the rest.
Steve
[The opinions expressed herein are my own
and are not to be attributed to my employer.]
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Steven M. Smith, Geologist Office: (303)236-1192
U.S. Geological Survey Fax: (303)236-3200
Box 25046, M.S. 973, DFC smsmith@usgs.gov
Denver, CO 80225
--The USGS National Geochemical Database NURE HSSR Data Web Site--
http://greenwood.cr.usgs.gov/pub/open-file-reports/ofr-97-0492/
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