What dictates galaxy and planetary system sizes?

In article , jacobnavia
writes:

Le 21/12/2016 =E0 13:32, Phillip Helbig (undress to reply) a =E9crit :
the quantities are
determined, as is everything, by the constants of nature and by initial
conditions,

Since most of the mass of a planetary system is in the star, the limit
to its mass is the limit of the mass of a star.

I'm not sure what you mean. Above a certain mass, nuclear fusion will
set in, so anything more massive is a star, by definition. (There is
also the Hayashi limit related to convection, so the lower limit for
stable nuclear fusion might be a bit higher, around 0.08 solar masses.)
The upper limit for a star is a few hundred solar masses. (Probably
anything more massive can't form before what has already contracted has
ignited, keeping out additional material.) I'm not an expert here, but
the mass range in stars is 2--3 orders of magnitude. It is not directly
(and if indirectly, very indirectly) to any size of the universe.

Now, stars when they become obese, start producing antimatter that
destroys the star before it is fully built, the limit on star sizes
determines, as a consequence, the size of the planetary systems...

Is that correct?

Not sure what you mean about the antimatter. Stars have a range in mass
as described above, the lower limit corresponding to the upper limit of
a planet. What the lower limit of a planet is depends on the definition
and, for some definitions, might depend on composition, but covers many
more orders of magnitude.