However, radioisotope dating may not work so well in the future.

Anything that dies after the 1940s, when Nuclear bombs, nuclear reactors and open-air nuclear tests started changing things, will be harder to date precisely.

The carbon-14 decays with its half-life of 5,700 years, while the amount of carbon-12 remains constant in the sample.

By looking at the ratio of carbon-12 to carbon-14 in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of a formerly living thing fairly precisely. So, if you had a fossil that had 10 percent carbon-14 compared to a living sample, then that fossil would be: t = [ ln (0.10) / (-0.693) ] x 5,700 years t = [ (-2.303) / (-0.693) ] x 5,700 years t = [ 3.323 ] x 5,700 years Because the half-life of carbon-14 is 5,700 years, it is only reliable for dating objects up to about 60,000 years old.

After the second half-life has elapsed, yet another 50% of the remaining parent isotope will decay into daughter isotopes, and so on.

For all practical purposes, the original isotope is considered extinct after 6 half-life intervals. A small portion of a meteorite is vaporized in the device forming ions.

HALF LIFE IS THE AMOUNT OF TIME IT TAKES FOR ONE HALF OF THE RADIOACTIVE MATERIAL TO DECAY INTO A STABLE FORM.

BEFORE DECAY BEGINS, ALL OF THE MATERIAL IS RADIOACTIVEAFTER ONE HALF LIFE, HALF OF THE SAMPLE REMAINS RADIOACTIVE AND THE OTHER HALF IS STABLEAFTER EACH ADDITIONAL HALF LIFE, HALF OF THE REMAINING RADIOACTIVE MATERIAL DECAYSWe use several radioactive isotopes to find the absolute age of events and objects because we know their half life.

Because its half-life is so long it is useful for dating the oldest rocks on Earth, but not very reliable for rocks under 10 million years old. This is ten times the age of the Earth, so very little Rubidium has decayed at all.

For this reason WE WILL NEVER CHOSE TO USE THIS ISOTOPE!

Trees undergo spurts in growth in the spring and summer months while becoming somewhat dormant in the fall and winter months.

When a tree is cut down, these periods are exhibited in a cross section of the trunk in the form of rings.

However, the principle of carbon-14 dating applies to other isotopes as well.

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