*Some words may be explained at the end of this article.

The Hafele-Keating experiment

To test some suppositions made by Einstein in relation to the Special Theory of Relativity, physicist Joseph C. Hafele (who started as an apprentice welder by the way) and astronomer Richard E. Keating  left a clock at the United States Naval Observatory and flew two cesium-beam atomic clocks round the world aboard commercial air-liners first eastwards then westwards. Back to earth, the three clocks . . . showed three different times.

Time dilation and the Special Theory of Relativity (STR)

According to the Special Theory of Relativity,

clocks in motion run slow

To notice this effect, the clock you are observing must move quicker than yourself!


One illustration of the results of the above experiment would be : let us say we have two clocks. The clock that will be left on earth shows 8:00 o’clock and  the clock boarding a rocket also shows the same time. However, after a ride in space, back on earth, the clock left behind shows 10:00 while the one that went in space shows 9:00

Imagining it in terms of humans, the one coming out of the rocket will be younger than the one staying on earth. Imagine a 50 years-old voyage. . .

What is time?

A discourse about  time will require quite a long and interesting explanation, too long to be included here. A simple explanation of how we use and define time in everyday life is as follows:

Suppose we set a ball bouncing up and down indefinitely. The highest it reaches is let us say 3 meters. Each time it comes down we say that it has completed one bounce. A friend might say to another : “i’ll meet you on the 8th bouce at 2.5 meters”. That’s how we define our time. We say : “i’ll meet you when the earth has completed such amount of spins”, that’s for days and for time of the day : “when the elevation of the sun is such”

Fragmented time?

In the experiment above, it was not really time that slowed down, but motion. The motion of the atoms of the clocks slowed down and so do the atoms of the persons . The existence of different time records shows that time as we conceive it is relative. We cannot really say : it is 3:00 now, because not everywhere in the universe the time is the same, unless of course we force everybody to convert their time to our time.

Towards universal time

Universal time can exist, one method is the force method – forcing everybody to calibrate on ours. But there is something which might reveal the key to the existence of a universal time, a time-keeping method independent of motion and that clue  is . . . life expectancy and time of death.

If both the person who traveled and remained young and the one who aged quicker on earth die at around the same time, if this happens on large scale, we might presume that only the effects of age vanished or remained the same . . . remain young or old, your life expectancy remains the same. The rocket ride would just be like applying a facial cream to keep the face-look fresh.

Ending Words . . .

Your watch does not keep time, it only listens to motion. Motion, motion, motion, dynamism cannot be ignored !


*Time dilation explained here

*The experiment here

*A cesium(-beam) atomic clock : A “cesium(-beam) atomic clock” (or “cesium-beam frequency standard”) is a device that uses as a reference the exact frequency of the microwave spectral line emitted by atoms of the metallic element cesium, in particular its isotope of atomic weight 133 (“Cs-133”). The integral of frequency is time, so this frequency,9,192,631,770 hertz (Hz = cycles/second), provides the fundamental unit of time, which may thus be measured by cesium clocks. source here