Time Dilation by Latitude

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

From The Fascinating Life and Theory of Albert Einstein (Archive):

Predicted by several authors at the turn of the 20th century, and later verified with various experiments, the phenomenon of time dilation due to velocity is a known phenomena. Experiment such as the Hafele and Keating Experiment showed that time dilates in on-board atomic clocks when two jets recede quickly away from each other. NIST was able to show (Archive) that time dilation by velocity can be shown to occur at speeds comparable to 20 miles per hour:

It is reasoned that, since the Earth is rotating, time must also dilate according to the different latitudinal speeds of a rotating Earth. Precision clocks were not yet advanced enough to measure the effect at the time of Einstein's prediction, but with the advancement of atomic clocks over the years there have been efforts to use these technologies to measure and demonstrate this effect.

University of Maryland
https://umdgrb.umd.edu/~goodman/review/ThemeGroup2_Exp.ppt (Archive)

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



Clock Transport to Thule
A University of Maryland at College Park slideshow shows the following (Archive):



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 (Archive)

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.

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

Luboš Motl
Theoretical physicist Luboš Motl (bio) also uses the Equivalence Principle to cancel out the effect. From his blog:

https://motls.blogspot.com/2014/07/is-time-going-slowly-near-equator.html?m=1 (Archive)

Discover Magazine
On this topic Discover Magazine explains the identical clock rates as a result of Einstein's Equivalence Principle:

Discover Magazine - Einstein’s ‘Imaginary Elevator’ Thought Experiment Proven Right Again

Addendum
The above authors use Einstein's Equivalence Principle to explain why clocks at sea level all tick at the same rate across the surface of the Earth and champion it as a success of Einstein, despite Albert Einstein making the opposite prediction on the matter. Possessing more knowledge about Einstein's theories than Einstein himself, the writers salvage the matter by telling us that the expected time dilation is erased by the Equivalence Principle. The Equivalence Principle is a principle of nature which says that effects on Earth are indistinguishable from an environment which is accelerating upwards.

From a University of Iowa presentation (Archive):



This approach of using an upwardly accelerating Earth as an explanation for why clocks at sea level all tick at the same rate is one which we can only express agreement with. Curiously, this principle not only applies to gravity, but to the rotational motion of the Earth as well. It has been argued that the Equivalence Principle is only a local effect, yet we find university explanations which utilize it as a worldwide effect to explain why time dilation does not occur at different latitudes due to the different latitudinal speeds of the Earth. Dr. Motl even goes as far as to say that it is only possible to cancel out the effect by using the Equivalence Principle and that any other argument is assuredly incorrect.

Time dilates at different altitudes in agreement with an upwardly accelerating Earth1, but not at different latitudes as suggested by a rotating Round Earth. It once again dawns upon the thinking man that our Earth is not the globe of popular credulity, but an upwardly accelerating plane.

Footnotes


 * 1 The Equivalence Principle predicts that time dilates at different altitudes. See:
 * Evidence for Universal Acceleration: Gravitational Time Dilation
 * The dedicated page for Gravitational Time Dilation