How reliable is carbon dating
By tipping the glass when the egg starts cooking, one learns when three minutes are up and the boiling should be stopped.
Carbon-14 makes up about 1 trillionth of the earth's atmosphere, so these minuscule quantities are what scientists rely upon.
Carbon dating works only with material that was once alive.
It does not work on rock, for example, but does work on wood.
One also assumes that all the sand is in the bottom of the glass when one turns it over. He must look for something in the bone which disappears over time, as the sand disappeared from the top chamber of the egg timer.
The disappearance must take place at a known and measurable rate.