There is an assumption in your question that the cosmos / universe was generated.
Although founded on some clear observations about microwave background radiation, the big bang theory is simply one of many such. In reality, the Judeo-Christian bible has as much evidence for their genesis theory as scientists do for theirs.
My favourite theory is that the universe has always existed, there never was a start and there never will be an end. The microwave background is the result of radiative energy and gravity interacting.
Other people will have different views.
None of us have any way of measuring this.
With respect to dimension, If we live in an expanding universe, then surely our measures are expanding at exactly the same rate as space-time. So how on earth can we expect to measure anything reliably?
Many scientists suggest using the wavelength of some specific frequency of light as a fixed, absolute measure. If space-time is expanding uniformly then so is that wavelength.
This suggests that the whole concept of 'dimension' may be a fallacy in itself, if we 'believe' in cosmogenesis.
You wrote: " Many scientists suggest using the wavelength of some specific frequency of light as a fixed, absolute measure. If space-time is expanding uniformly then so is that wavelength."
But if space-time is not expanding uniformly, which is an axiomatic assumption, then wouldn't the speed of light be a true absolute measure that we could trust?
Wouldn't this possibility be more simple and make more sense, generally speaking?
And what if we consider the zoom a dimension that curves the 3 normal dimensions forming a hypersphere?
At one end we would have the whole universe at one point (the Big Bang) in the other the smallest possible objects (electrons or maybe neutrinos, always however small they are, they will be greater than 0, because otherwise they would not exist).
The 3 normal dimensions are created by the zoom definition itself and the zoom can be shown to be created by the energy that contains the universe and related to E = mc ^ 2 that really is the energy necessary for an object to exist, the energy needed to bring that object from the BigBang to its corresponding zoom level
In my view there would be a number of alternatives to consider
Space-time is not expanding, red-shift of cosmic radiation to the microwave background is a result of gravity / light energy interaction (If I may ignore the res and blue-shift related to inter and intra-galactic movements). This interaction with gravity is not 'tired light' as some have suggested, tired light is defined as light that has been interfered with by inter-galactic matter such as space-dust.
Space-time is expanding and the speed of light is fixed in absolute terms related to the time at which each photon were emitted. This, I think, is the essence of your proposal above. The problem with this is that this would create a general blue-shift of light. Because as the universe expands and light wavelength does not, light will have an apparent shortening of its wavelength. The universe is not, as far as we can measure, bathed in the gamma-radiation that would result from this continuous blue-shift.
Space-time is not expanding for matter (which is fixed in relative terms), but is expanding for energy. This would result in a cosmic red-shift as, to a matter-based observer, the wavelength of light would continuously increase. This situation would harmonise the view that gravity is a warping of space-time with the idea that gravity is a form of inertia. Energy travelling near mass would have to travel longer distances and the closer it gets to mass the longer the distance travelled and the more time taken.
Einstein and a lot of others have simply got it wrong. The speed of light is not constant but is frequency dependant (energetic blue light travels faster than red-light). At this point, all bets are off, nothing in our science would be fixed and all the major assumptions used in physics would be invalid.
Dear Robert Shour, the dimension of the Universe and cosmogenesis, respectively, is determined completely by human perception for given stage of human evolution. We consider the space where we live as 3-dimensional one. Einstein created the theory where the time is the 4-th coordinate of the curved space-time. Contemporary scientists assume that the time flows only from the past to the future. Of course, General Relativity creates more bread picture of the World. But it is evidently that the model of the World will be more complete in further. Contemporary scientists study 4-dimensional models of the Universe. Why must we consider only 4 dimensions? Why the time must possess only one dimension and why it must flow only from the future. Our models of the Universe correspond to our consciousness at the given time. When human consciousness reaches more high level, people will consider our people as multidimensional one.