Einstein predicts two types of time dilation, both of which have been tested and confirmed. One is…
When we talk about time in physics, it’s always about measured time. To talk about time in any other way is not physics, and does not belong to the realm of this discipline. This means that all discussions about time have to involve the concept of a physical clock that can be assembled in the physical world. To do otherwise would be to invoke God’s clock, which would bring us into the realm of religion and metaphysics.
An important aspect of any clock is the way it involves photons or neutrinos in its operations. This ties time up to the constant c, the speed of light, in such a way that c cannot in any way change from its measured value. The constant c and physical time are two aspects of the same phenomenon, manifest in the way energy propagates through inertial matter.
Inertial matter is made up of protons and electrons, both hollow and balloon-like with plenty of holes to let the aether in and out. This means that energy propagates along a curved surface when it is communicated from one particle to another. At the subatomic, there’s something curved about time. While this can be ignored completely at the macro level, it cannot be completely ignored at the level of subatomic particles.
In contrast to time, which has a curved aspect to it, space is completely flat. All three dimensions are straight lines. This means that calculations involving both distance and time at the subatomic will encounter a tiny mismatch due to the difference of geometries involved. With this in mind, this YouTube presentation by Alexander Unzicker on the constants c and h comes to mind. It appears that Unzicker has reached a similar conclusion about the nature of space and time, namely that one has some kind of curvature while the other is flat.
(Many thanks to Freddie Thornton for having brought the work of Alexander Unzicker to my attention.)