CREATION
SCIENCE: Radioactive Dating Techniques
The dating
of fossils and rocks using radioactive dating techniques is considered
by most to be a very reliable ‘scientific’ method. It is almost universally
accepted that these procedures attribute an absolute date to rocks and
therefore also to the fossils found within the rock. This results in the
belief that the earth is billions of years old. The best known of these
techniques is radiocarbon testing (or carbon dating). Other methods used
are known as potassium-argon, rubidium-strontium and uranium-thorium-lead
testing.
Radioactive
substances are unstable. They decay to form new substances at a particular
rate. The rate of decay is measured in terms of a ‘half life’ which is
the time taken for half the amount of the original (parent) substance
to become the new (daughter) substance. If you knew how much of the parent
element you had to start with, the remaining amount of parent element
and the known decay rate would indicate how much time had elapsed in the
decay process.
Radiocarbon
dating, for example, is based upon C14 (carbon) decaying to
C12. Living organisms have a set C14 to C12
ratio. Scientists use this to determine how much C14 was present
in the living organism. When the animal dies, C14 decays to
C12 with a relatively short half life. By analysing the remains
of living matter, one can make an estimate as to how long ago the organism
lived.
Radiocarbon
testing has proven to be quite unreliable. Scientists have observed large
errors when dating something they already knew the age of. This is largely
due to the fact that the object being tested was not in a closed system.
Through time, carbon was added or taken away by environmental interference.
The short half life of radiocarbon is also only suitable for testing fossils
or other dead matter no more than a few thousand years old. It is therefore
never used to determine the age of fossils in the geological column as
they are considered to be millions of years old. Interestingly though,
fossils submitted for radiocarbon testing yield results and fix their
ages at only a few thousand years.
Other radioactive
dating techniques have longer decay rates and are therefore more suitable
for dating objects older than a few thousand years. The elements used
in these tests are inorganic. You therefore do not know how much of the
parent element you had to start with. The assumptions you need to make
to use these methods are:
- how
much parent element there was originally.
- a
constant decay rate throughout time.
- a
closed system.
Carbon dating
has already shown that 2. and/or 3. are not valid assumptions.
"Thus
the assumption of immense ages has not been proven."1
Yet radiocarbon
dating is still used and purported as scientific proof of the earth’s
magnificent age.
1. An evolutionary
geologist (Dr Y.F. Zheng) recently wrote a paper in the international
journal Chemical Geology to collate the claims of various mathematical
techniques used to try and remove the problem of unknown initial conditions
in radioactive dating. His conclusions were uncomplimentary. This is one
of his quotable quotes.
Becky Conolly
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For
more information and resources contact:
AFRICA CHRISTIAN ACTION
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