They didn’t know it was finite, and so, they devised a calculation system which would work for infinite space system.
Of course, there would be discrepancies, and so, hopefully, when calculating those extreme, they would be able to find out where part of the inaccuracies came from.
The limit of light wave expansion, or other forms of energy with the smaller amount of mass, is the speed of the expansion.
The speed is in relation to the medium into which it is propagated.
For instance, let’s say a beam of light traveling on a train, with an observer holding a flashlight on the train, points the flashlight forward, on the same direction as the train, and the train travels at the speed of light.
Now, of course, the train cannot travel at the speed of light.
Then, what if there is another train going in an opposite direction, with a 2nd observer and another flashlight, pointed in the opposite direction.
Now, both trains are travelling in opposite directions, both towards one another, but under the speed of light.
Each beams of light of those 2 flashlights travel at the same speed of light, or does it?
Would the speed at which they reach one another be double of the speed of light since they are in opposite directions, and, both towards one another?
What would happen to an observer outside the train?
Would he see the light beams reaching each other at the maximum speed of light, or would it be double?
Now, there is something very important about that speed or any other speed which is the cause of any speed.
That is, the medium in which that speed travels.
Speed being the number of distance per second travelled.
If that distance expands faster than the speed of light, then, what would the speed of light in that expanding medium be?
Will it be affected by it?
Will the maximum speed be the same?
If the speed of light is then faster than the speed of a light in a space medium which is more stable, how can it be measured to be faster?
Will it be in relation to the medium which is more stable, or the one which is more expanding?
So, anyways, the light travels at the same speed in the expanding medium, only the medium does expand faster than the speed of light.
The reasons the medium expands faster is due to astronomical forces on other scale than 4 or 5 dimensional forces.
What about the light beams in opposite directions?
Those should not reach each other at a speed faster than double the speed of light, and only due to properties related to their respective vectors.
Each is not faster than the max speed.
There is no speed of approach faster than double that speed, unless one of the medium or both, is or are faster.
However, light can be used to measure expanding medium due to it’s speed properties.
So, I am not so sure about the explanation in the videos as I have not verified most of it .
I do recognize good parts of it though.
On another scale, only systems which are the most far from our system are expanding faster than the speed of light.
There are no such expanding systems that I am aware of, which are in close range to our system.
Some of the limit of light wave expansion in space are around SuperNova and Quasar.
Those effects knocked out some of our earth satellites for certain amount of time at and during those period of time.