Time Dilation by Latitude

Time Dilation by Latitude refers to Albert Einstein's prediction that time would tick slower at the equator than at the poles.

From The Fascinating Life and Theory of Albert Einstein:

  “ In Einstein's original paper on the Special Theory of Relativity, "On the Electrodynamics of Moving Bodies", he mentioned a thought experiment using two identical clocks. One clock was placed on the equator and the other at one pole of the Earth. The clock on the equator had a faster speed then that at the pole due to the rotation of the earth. He claimed that the clock on the equator would run slower than the one at the pole. ”

Precision clocks were not yet advanced enough to measure the effect at the time, but since the invention and and advancement of atomic clocks there have been efforts to use new technologies to measure and demonstrate this effect.

University of Maryland

https://umdgrb.umd.edu/~goodman/review/ThemeGroup2_Exp.ppt

In 2005 the University of Maryland found that there was no difference in clock time with Atomic Clocks:

The University of Adelaide

The equivalence principle as a stepping stone from special to general relativity: A Socratic dialog
S. P. Drake
School of Chemistry and Physics

Full Text Link

Professor Drake at the University of Adelaide explains that there is no time dilation between different latitudes. Professor Drake then proceeds to provide an explanation for the lack of time dilation. The paper is written in the form of Socratic dialog.

  “ Kim: Your lectures on special relativity fascinated me, and when I got home I wondered if I could construct a simple experiment to prove or disprove time dilation, the aspect of special relativity that interests me the most. While lying in bed before dozing off, I realized that a clock placed at the equator should run slower than a clock placed at the pole. So I did a little calculation and found that special relativity predicts that a clock on the equator runs slower by about 100 ns per day with respect to a clock at the pole. Although this effect is not large, it is certainly measurable with modern atomic clocks. So I went onto the internet to see if I could find any reference to such an experiment and to my surprise I couldn’t.

I was starting to get so frustrated that I couldn’t sleep. I glanced at the clock - 3 am. I thought to myself “How accurate is my clock?” I should check it against internet time. Then it occurred to me that the world timing standard organizations must mention a latitude effect on local clock accuracies. So I went onto the internet again and checked The Bureau International des Poids et Mesures² because the Bureau calculates the international atomic time from atomic clocks located in more than 30 countries around the world. I was sure that I must find something about the latitude effect on their web site. After spending hours trawling their site and then other sites on the web, I came up with nothing. There was a discussion of the relativistic effect of placing clocks at high altitudes, but nothing about latitude. In my despair I gave up and collapsed into a fitful sleep.

I came to see you today in the hope that you could cure my insomnia.

Sam: You are in good company in thinking that clocks at the equator and the pole should tick at different rates. Einstein himself predicted as much in his famous 1905 paper on the special theory of relativity.³ Luckily for physics the effect was not measurable with the instruments of the day because Einstein’s prediction would have failed to match experiment.

Let us return to your findings:

1. According to the special theory of relativity a clock located at the equator should run slower than one at the pole and
2. Empirically, all clocks located at sea-level on the Earth’s surface tick at the same rate, regardless of latitude. ”

Explanation

In order to explain the lack of this effect on a rotating earth, the Professor Drake explains that clocks tick the same rate by virtue of Einstein's Equivalence Principle:

  “ Suppose you are floating in a room with no windows or doors. All of a sudden, you feel a force that throws you against the wall. If there were two possible forces, gravitational and centrifugal, are you able to determine which force you are feeling?

...The idea that you can’t know if the force is a uniform gravitational force or a combination of uniform forces, is called the equivalence principle. What does it tell you about clocks on the surface of the Earth? ”

Addendum

The above author uses the Equivalence Principle to explain why clocks all tick at the same rate across the surface of the Earth. The Equivalence Principle says that gravity operates as if the earth were accelerating upwards.

https://slideplayer.com/slide/8138482/

We may only agree with this argument of using an upwardly accelerating earth as an explanation for why clocks tick at the same rate. Curiously, according to some, this effect not only applies to gravity, but to the rotational motion of the earth as well. Time dilates at different altitudes in agreement with an upwardly accelerating Flat Earth^[1], but not at different latitudes as might be suggested by a rotating Round Earth.

It has been argued that the Equivalence Principle is only a local effect, yet we find university explanations which use it as a worldwide effect.

See Also

• Evidence for Universal Acceleration: Gravitational Time Dilation