How Old Are The Pyramids?

Introduction

Archaeologists believe Egypt’s large pyramids are the work of the Old Kingdom society that rose to prominence in the Nile Valley after 3000 B.C. Historical analysis tells us that the Egyptians built the Giza Pyramids in a span of 85 years between 2589 and 2504 BC.

Interest in Egyptian chronology is widespread in both popular and scholarly circles. We wanted to use science to test the accepted historical dates of several Old Kingdom monuments.

Previous estimates

One radioactive, or unstable, carbon isotope is C14, which decays over time and therefore provides scientists with a kind of clock for measuring the age of organic material.

The earliest experiments in radiocarbon dating were done on ancient material from Egypt. Willard F. Libby’s team obtained acacia wood from the 3rd Dynasty Step Pyramid of Djoser to test a hypothesis they had developed.

Libby reasoned that since the half-life of C14 was 5568 years, the Djoser sample’s C14 concentration should be about 50% of the concentration found in living wood (for further details, see Arnold and Libby, 1949). The results proved their hypothesis correct.

Subsequent work with radiocarbon testing raised questions about the fluctuation of atmospheric C14 over time. Scientists have developed calibration techniques to adjust for these fluctuations.