Imagine the universe would contain only one galaxy. Would its light travel away from it in empty space the way it actually does for galaxies?
I can't see why not. That's exactly what it's doing right now.
Point four is not a fact. You're even discussing it here below.
Point four is a fact observed by Planck satellite (the "radiating" epoch); what I "stipulate" below is the implications of that fact with explanations.
Moving with regard to what? To itself?
In regard to the intensity of the kinetic energy present, which gives it light-speed. Light-speed is an "invariant" and it's not relativistic; so its speed is "in regard" with nothing else.
what if the universe had started with a big particle 13 billion light years in diameter,
That's what it is "right now"; but it's a big "massless particle" called a photon and it as been expanding since the beginning; so it couldn't start at this "size". On the other hand, being a photon means that it travels at light-speed. In that sense the universe has no "size" and is always at the "present". In fact in the same "state" it was in "zero motion" = time zero. Observable universe becomes then, only what travels at less than light-speed. So "motion" is the only "basic" thing that really exists; and that "less than light speed" motion has a beginning which is time = non null (zero plus) at the beginning of Planck's era; which lasted until 10^-43 sec after time zero. Pretty simple; isn't it?.
then started to divide into smaller and smaller parts with time. This way, the stars would have been big parts some time ago, and the planets smaller parts, and both would have continue to divide into smaller parts until these parts become the atoms.
Put your video on "forward"; it's on "reverse".
All right, it doesn't make sense either, but it shows what our imagination can do when it tries to imagine the beginning of things.
Not of "things"; but beginning of "space". And what you want to say happens only when the premisses to guide imagination, are not based on "facts". That's why they're so important to specify.
If you don't find it, your theory stands on nothing.
It only stands on the idea that light moves independently from bodies, and that it takes time to go from one body to the other. That's simple, but that's enough. Einstein added its relativity principle to the equation, but it was superfluous, and he did not realize that it did not work for light.
So we have been discussing for absolutely nothing. What I remark is that you take care not to follow or discuss the logic of my proposition; where you might find what you're looking for. So it's no use to continue.
You don't like the Higgs as an explanation for inertial mass, but you did not replace it.
You didn't read the 5 first pages of this discussion because you would have found a far more simple explanation for mass than the Higgs particle. So you're talking only for "conversation". The problem is that you're making affirmation without checking. No use discussing this way. You don't even follow my proposition where I just mentioned that "we are going to find later the reason that mass energy has to have "volume". I never wanted to discuss with Jeannette Bertrand who was "talking for talking". :-)
I understand your choice, but why did those neutrinos have to be massless at the beginning,
I've explaine that they DID NOT have to be massive at the biginning; thay had to be MASSLESS. And they don't even have to be massive today.
Couldn't a massive particle have begun separating in halves the way you describe it in your book?
That's the "decaying" process; nothing new there. You present it as a biology process which is not the same but similar (not identical) because more "evolved". Decaying couldn't happens during the "radiating epoch". Decaying started at 10^-36 sec.
Two massive particles separated by a distance also define space, no?
No!!! It defines a "distance". There is "space" between particles but it's the same space that is all around them. So particles don't define "space"!; they define "distances". The distance between two particles is only "one single distance" of all the "distances" that define "space".