"I like to engage the public because when I was in high school, I had all these questions about anti-..." — Michio Kaku

Technologies that may be realized in centuries or millennium include: warp drive, traveling faster than the speed of light, parallel universes; are there other parallel dimensions and parallel realities? Time travel that we mentioned and going to the stars.

In Einstein's equation, time is a river. It speeds up, meanders, and slows down. The new wrinkle is that it can have whirlpools and fork into two rivers. So, if the river of time can be bent into a pretzel, create whirlpools and fork into two rivers, then time travel cannot be ruled out.

Time travel and teleportation will have to wait. It may take centuries to master these technology. But within the coming decades, we will understand dark matter, perhaps test string theory, find planets which can harbor life, and maybe have Brain 2.0, i.e. our consciousness on a disk which will survive even after we die.

The energy necessary to create a wormhole or to wrap time into nuts is incredible. It's not for us. It's maybe for our descendants who have mastered the energy of this technology. So if one day, somebody knocks on your door and claims to be your great great great great granddaughter, don't slam the door.