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I understand your point, which 'in short' refers to the scale factor & the variable magnitude of forces according to this scale factor. thanks

I'd like to ask about the effect of sudden heating just after super cooling on whatever material(metal, aluminuim, gold,...etc.) or vice versa(sudden cooling just after great heating), I think it differs who is first, super cooling or great heating. why does Pyrex break of such effect knowing that Pyrex manufactured to withstand heat. regardless Pyrex glass, I am thinking about the chemical or physical phenomena after such consecutive change in temperature on any object/material. any help much appreciated, thanks in advance.

thanks for all the answers, but the point is that I'm not a Physicist, I am just a Civil Engineer who is interested in many fields of science including Physics. I remember some of the basic theories some of you have mentioned like "Relativity theory of gravitation" by Einstein, but I didn't learn about it thoroughly. I thought the explanation of our Earth core gravity would be easily illustrated & understood, but from all that previous debate, I assume it's rather more complicated than I though or I should restudy physics thoroughly to feed my needs of such questions. Do anybody have a recommendation for a good comprehensive start?

I've been always wondering what is the real explanation of gravity. How & Why are we attracted to Earth regarding different materials, I mean Earth's gravity attracts everything(living organisms, mountains, oceans, even air) so what is it exactly the physical reason for this kind of attraction. I couldn't even compare it with Magnets, as magnets attracts only metals, when Earths gravity attracts everything. I would be grateful to any answer, thanks.