If Christoph Schiller is right about the maximum force in nature being 10^ 45 Newtons (c^4 / 4G) then if quarks have a radius and are not point like this would mean (assuming a quark is spherical and made of partial electric charges on the surface of the sphere) that the minimum size a quark can become is given by: k q^2/ r^2 = 10^ 45 i.e radius of quark = 10^ - 37 metres. I have not used quantum field theory because I do not think it applies to forces between the partial charges of a quark sphere. The minimum radius of the universe at the time of the Big Bang would then be 10^26 x 10^ - 37 = 10 ^ - 11 metres. (10^26 because I am assuming a density of 1 quark per cubic metre in the current universe where there are 10^ 78 quarks). Quarks with a finite radius overcome the problem of a singularity in relativity!