I studied about Casimir effect of attractive force, analogous to 18th century French sailors: "Where two ships are rocking from side to side in conditions with a strong swell but light wind, and the ships come closer together than roughly 40 m, destructive interference eliminates the swell between the ships. The calm sea between the ships has a lower energy density than the swell to either side of the ships, creating a pressure that can push the ships closer together." -http://en.wikipedia.org/wiki/Casimir_effect#Analogies With this, I figure out relation about other forces. But before this, I need to point out my postulates: a)constructive interference is repulsive on masses relative wave b)desdructive interference are attractive on masses relative wave c)In-phased waves are attractiven on waves itself d)Out-phased waves are repulsive on waves itself 1.In about diffraction and interference of electrons or photons. Since in-phased wave are attractive while out-phased wave will repel (side by side), hence constructive interference are cause by this attractive force and destructive interference are cause by the repulsive force. I am sure that electrons and photons always discrete. It sure looks very confusing, because you need to swith oppositely the way you think, refer to above a,b,c,d postulates. 2.The gravity force is very similar to Casimir effect and analogy of those ships on sea. Consider time-space and mass, mass somehow cause time-space curving, and time-space are in same phase and had only one direction (time never look back). When two masses close together, destructive interference of spce-time happened between the masses, consider if time-space as wave, so created always attractive gravity. Or in other way round, time-space wave are repulsive as there are out-phased, hence the spaces push away from the middle of the gravity field. 3.Why like charge repel? Well, think of that gravity can also be said by repelling the out-phased space-time wave itself. The whole charge itself is wave, so the waves are repelling. Like charge is repelling. Con charge is attractive, because destructive interference causes attractive force. Althought both positive and negative field are waves, but together they are refer as destructing wave and field, this is attractive. 4.Charge field move fastest and they don't have time, however, a moving charge field is another story. As charge field move, it creates wave, and when two waves of these move along side, attractive force generated, what I mean here is magnetic force. So, parallel of current is attractive, because in-phase waves are attractive. This is very similar to diffraction and interference of electrons and photons, however these statement is not good enought, because there are always both repulsive and attractive force between two parallel current, unless mathematicians proved that attractive force is greater. It also gives me idea of moving gravity field, creates another force? Generate gravitons? Lastly, I had to say that all above are only postulation, not yet determined. I don't play with maths. So maybe someone can help me to do this. Or not.