"The further away among the expanding pieces of an explosion, the faster their rate of separation due to the angle of expansion."
That is, if after some time in an explosion (for example, our Big-bang) two pieces of material from it are very close together, it is because they go in the same direction and barely separate.
But if two pieces are very distant it is because they lead very different directions and that is why they are separating quickly.

As we have seen, my cosmos model tells us that our galaxies are the equivalent (at stellar level) to the cosmic rays of high energy at atomic level.
And both are also equivalent to photons at sub-atomic level.
Therefore, these three elements are energy particles (when moving to great speed) that beginning their march with 300.000 k/s and moves through space to that speed.
But looking by a moment our galaxy and let us see some results, as can be the speed of the galaxies.

Speed of galaxies.

As I have mentioned that galaxies move near to the speed of light.
Then the question is:
- Why we think that they go much slower?
And the answer is simple:
- Due to the speed-chords (expansion angle) among the nearest galaxies to us that is very small when these galaxies have the same path than ours.
For instance:
When an explosion takes place, not all the resultant fragments go separating among them to the same speed, but rather those that go in the same direction (and so, very parallel among them) go separating very slowly; and those that go in contrary sense move away very quickly.
Nevertheless, if we locate ourselves on one of these fragments and proceed to measure the speed from our position, regarding to the nearest fragments alone, then we could think that we go very slowly.
However, if we measure the speed regarding to those that go in contrary sense, we would believe that we go very quickly.
And that is what happens in our galaxy when we measure our possible speed regarding to the nearest galaxies that go in the same direction and quite parallel to us: Because that we will take out the conclusion that we go very slowly.
And clear, with relationship to those that go in opposed sense we cannot measure because they are very far from us and we cannot see them.
So here we take out a very erroneous conclusion: The speed of our galaxy is very small with regard to that of light, when it is the same one (300.000 km/s., see drawing.)

On the other hand, the apparent influence of a possible dark matter in the maintenance of galaxies together more strongly than what it is expected, it is in part due to the motion in straight line from the center of the Big-bang toward the exterior at the speed of light c.
Say, it is the high velocity in radial way what produces the appearance of more attraction among them.

Then, to this relative speed among galaxies (and not regarding to their departure position) it is to what we call Speed-chords of galaxies, because it is really represented by the circumference's chords that is created among the galaxies that expand and the initial position of the Big-Bang as circumference centre.