Why does mass slow time?

[Overmind]

A gamma ray has more energy than a radio wave, but yet they travel at the same speed, this is due to the photons of the gamma rays ticking at a slower rate, thus it takes more Time to cover the same distance of linear space due to the oscillations of the photons.

As I determined so far, if the energy is different, space is not the same anymore, therefore the distance required to be covered will be different.

I've always thought the speed of light in vacuum is constant (even through different mediums, but propagation rate varies) ...  Are you referring to casmir effects on light?    Do you have a reference?

The speed of light in vacuum is given by the General Cosmic Filed that in outer space is next to constant. However, each time you have anything near-by that adds additional overlapping field, the speed differs. For example, the speed of light in vacuum near the Sun is different from the speed of light in vacuum at two light years away from the Sun. There is no direct way to observe this because the tools with which you observe are affected by the same overlapping field that modifies the speed of light.
To give a simple example: let's way you want to measure the length dilation of a rail road when the outside temperature is 30C above the normal one. If you have a one meter steel bar that you measure the rail road with, when you do the measurement at standard temperature you will get a value of 'x' (let's say x times 1 meter equals the rail road length). If you measure a T+30C, you will get the same result 'x' because the steel bar will suffer the same length dilation as the rail road.
If you want to correctly measure this way, you must isolate the steel bar form the environment temperature.
This is similar for the light. If you want to measure length contractions and light speeds, you will have to isolate the whole measurement system from the General Cosmic Field present in all space because otherwise you will get a constant value every time you measure, just like they actually did with the speed of light (that why it's being assumed it's a constant in space).

So, getting back to the topic, mass does not alter time, but it modifies space length so that's why an object will take a different amount of time to get to the same destination - because it no longer travels the same amount of space.

[newbie123]

However, each time you have anything near-by that adds additional overlapping field, the speed differs. For example, the speed of light in vacuum near the Sun is different from the speed of light in vacuum at two light years away from the Sun.

This is incorrect.   The speed of light is constant (and has been shown to be constant experimentally) near the sun or 2 light years away from sun..  The wavelength will shift (red/blue) depending on the gravitational well around the photon..    A photon near the sun will have less energy (less wavelength) than the same photon further away from the sun...   BUT the velocity of the photon remains the same... This is well known.



"General Cosmic Field"  Is this a term you made up?

[Overmind]

It's not well known...it's incorrectly measured.
The new tunneling experiments prove that the speed of light is not constant.

The General Cosmic Field is the equivalent of the term 'Aether' used by the scientists long time ago and it's formed of all the overlapping fields in the Universe.