[WhiliaStelt]

Because avoiding the law of conservation of momentum is what the article seems to be talking about when they talk about manipulating gravity.
e.g. they talk about accellerating without applying a reactive force. Well it is not like that
If you move inertially then there is no momentum generated

so in effect you could scream up to a brick wall... and just before the wall you turn off your generator.... you would then be stationary (it is slightly more complicated in many circumstances)

This concept was demonstrated very well in a kids movie "The Flight of the Navigator".... only as an idea

However NO LAWS of physics are broken.

Rippley's Believe it or NOT, LOL.... Eyes Wide Shut, so it can never be, can it ?

BUT IT IS !!!!

As an aside
The discussion re manipulation of the electrodynamic gravity field is grist for my mill
especially cosmic fields