Why we are searching quantum gravity effect at the planck scale? The question seems very stupid (and may be) but let me explain. I define a quantum object when his action is of the order of planck constant \bar h. namely A~E \delta t~\bar h. So if i take a small amount of energy E i can take \delta t big. Applied to gravity i can say that if i take a small (in terms of energy) gravitational system, i can see quantum effect at macroscopic level. In the case of electromagnetism i can have photon of macroscopic length. In my opinion this claim is true, but is very very difficult to find or to build such object, like in the case of photon is very difficult create only one photon of macroscopic length. Is this true?