I heard somebody talking about dark matter, well that person is completely lost my drift. I think he needs to read my post again. I repeat 'This X is some entity which was present before big bang & was responsible for release of massive energy which converted into weak force, strong force, gravity & dark energy (controversial though) & also matter & anti matter. Most the matter & antimatter was nullified each other with only a fraction of matter left which was responsible for creation universe. Dark matter is a very heavy thing with very strong gravity.