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Henri
Becquerel discovered radioactivity.
It was soon
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realized
that the energy from radioactive decay was
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enough
to keep the planet hot. But more
than that, it could
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be
used for dating rocks.
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Used
mother/daughter isotopes as way to measure earth’s
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age. Assume that one no daughter to start with
and there is
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only
one way to make daughter and no mother element is
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added over
time.
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Using
radioactive dating techniques, the age of the Earth
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has
been shown to be (again and again) 4.65 billion years.
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