I'm vexed by this problem of moving around in space. As Alexander posted earlier in this forum, "You do not have to enter crashing gravity of black hole or to warp space to travel the entire Universe in a life span of one generation only. If you just keep moving with very comfortable acceleration a=9.8 m/sec^2, then in about a year you achieve the speed about 0.77c, in two - about .968c and so on. As your time slows down, it takes only 2.5 years for you to reach the nearest star, 11 years to get to the Milky Way downtown, 15 years to check in the Andromeda galaxy, and about 24 to cross the visible Universe." Any proposals on how we achieve constant acceleration (or deceleration for that matter)? I tell you this, it will not be any kind of chemical reaction, for obvious reasons. What other forms might an engine take that could do this? I think we need to understand more about just what space is really made of, because it most definitely is not "nothing". There is a power source there somewhere, whether it's gravitic, particulate, topographical or something completely outside our current math. My vote is gravitic. If we ever learn to harness or even understand this phenomenon in detail, I think the solution for practical space travel will point to itself.

What we really need to know is what to push against. Helicopter blades push against air and defy gravity. A boat propeller pushes against water and achieves forward motion. What else can we push against to lift a ship into orbit, or accelerate it though space? The earth has "gravity" because it's mass is big enough that it creates a depression in space steep enough that we are all stuck (luckily!) at the bottom of it. It bends space! Think of the stresses involved and tell me there isn't enormous potential energy lying around somewhere waiting to be found.

Sorry I double posted this, but I couldn't even find my first reply post it was so far down the list! I actually want to get a discussion going. I have lots of ideas, but very few facts, so I need some help to sort out "impossible" from "implausible." In my book, implausible is one brainstorm away from "done."