Do gravitational waves exist?

It seems that gravitational waves do not exist. All efforts to observe them have been unsuccessful:

• Gravitational waves discovery now officially dead
• Although there's strong indirect evidence of gravitational waves, no one has yet detected one directly

From the theoretical viewpoint, gravitational waves are ill defined because gravitational equations are non-linear. An energy-momentum tensor of a gravitational field also is under discussion since it reduces to the boundary terms. 

Moreover, it may happen that, being a Higgs field, gravitational field is not quantized, but it is classical in principle (#)

Archive