Tru Physics

Hafele-Keating Experiment

—

by

Tru Physics
in

Introduction

The Hafele-Keating experiment was a test of the theory of relativity. In October 1971, Joseph C. Hafele, a physicist, and Richard E. Keating, an astronomer, took four cesium-beam atomic clocks aboard commercial airliners. They flew twice around the world, first eastward, then westward, and compared the clocks against others that remained at the United States Naval Observatory.

Basics of the Experiment

The experiment was designed to investigate the effects of both special and general relativity. According to special relativity, moving clocks are measured to be ticking more slowly than stationary ones (time dilation), while general relativity predicts that clocks closer to a massive object will tick slower than those located further away (gravitational time dilation).

Calculations Involved

The predicted time dilation due to velocity (special relativity) and gravitational potential (general relativity) is given by:

\Delta t = \Delta t_{velocity} + \Delta t_{gravity}

where

\Delta t_{velocity} = \dfrac{v^2}{2c^2} \Delta t_0

and

\Delta t_{gravity} = \dfrac{GM}{c^2R} \Delta t_0

Here, v is the velocity of the aircraft, c is the speed of light, \Delta t_0 is the proper time on the aircraft, G is the gravitational constant, M is the mass of the Earth, and R is the radius of the Earth.

Results of the Experiment

The results of the experiment were consistent with the predictions of relativity. The time difference of the traveling clocks was in agreement with relativistic predictions, thus providing confirmation of the time dilation effects as predicted by the theory of relativity.

Conclusion and Impact

The Hafele-Keating experiment was one of the first empirical tests of the predictions of both special and general relativity. By showcasing time dilation effects in a real-world setting, it provided a significant confirmation of Einstein’s theories, and paved the way for further explorations of relativistic effects, such as those necessary for the accurate operation of the Global Positioning System (GPS).

Do you prefer video lectures over reading a webpage? Follow us on YouTube to stay updated with the latest video content!

Want to study more? Visit our Index here!

Comments

Have something to add? Leave a comment!