No, there isn't enough mass to close our space-time. If you travel too far forward, you will find yourself in a dead universe, where nothing ever changes. Kind of like CBS.Now that we know that they simply need to turn off their dampening field to travel forward in time through relativity, haven't they just made every space battle irrelevant? Granted if you jump time just to get away from the bad guy then how do you get back?? I am guessing that if you travel yet again far enough into the future you can find a way back. Kinda like shiny sparkle girl did in last week's episode.