Yeah that!! and it has to vaporize things/people without a trace like in Star Trek!!

 

Maybe 50 years down the road.

 

Well, Dr. Kaku did state that the most plausible of these inventions would take decades. What I'm hoping for most is the advances in propulsion that will enable travel at speeds faster than light or get around it. Necessity is the mother of invention so ships will have to have electro-magnetic shielding and plasma-based weaponry. Hopefully, alien civilizations we'll encounter are peaceful, but you never know.