Well we can do that now, only it would take a very VERY long time. For eg. The closest galaxy to us is Andromeda, it's 2.5MILLION light years away. So even if we figured out HOW to travel at the speed of light, it would still take 2.5million years. Current spaceships can't even do a fraction of that speed so it would end up taking BILLIONS of years. Best chances of us traveling through deep space with people on board, is with a warp drive and NASA is working on one right now 8)