In a sense, we can manipulate gravity just as well as we can manipulate EM fields. Take the nearest object with mass, and wave it around - congratulations, you just broadcasted a gravitational wave.

Can humans manipulate gravity?

The better news is that there is no science that says that gravity control is impossible. ... We are quite adept at controlling electromagnetic phenomena, so one can presume that such a connection might eventually lead to using our control of electromagnetism to control gravity.

Can gravity be altered?

It might be hard to believe that a force like gravity can be subject to whims of the changing seasons, or from shifts in land and water on the ground. But it's true: Earth's gravity is indeed changed by both of these factors.