According to GTR, gravity is not a force but effects of gravity is because of the shortest path which object follows. Since locally the space time is flat then one cant define energy density associated with gravitation. Gravitational waves are just space time variation which object follows. But if this is true then object gains energy according to inertial frame because object starts to move under influence of gravitational waves. Since energy is conserved and because of gravitational waves object is moving then does it means that gravitational waves have energy? Does having energy in gravitational waves means that GTR need quantization? Because energy needs a particle (graviton) to exist, like in electromagnetic field photon are carrier of electromagnetic field.
Edit: In theory gravitational waves can always have enough frequency (hence the wavelength) such that it interacts with electron. But if these gravitational waves do not have enough energy (but have wavelength of the order of electron size so that they can interact with electron), such that electron can excite to higher level of the atom. Then according to quantum mechanics since energy is not sufficient then the electron wont absorb gravitational waves energy. It directly means that electron wont move under space time variation. How can, matter have mass m will not move under space time variation? Does that constrain gravitational waves to have same constant "h" such that for given wavelength, the energy have to be that much sufficient such that electron will excite to other level? Or does it mean that we cant have wavelength of the order of electron size (which is not defined) in QM.