[AngryData]

If the craft could maintain a constant 1G acceleration the entire time or more it is feasible to get near the known edge for the traveler, assuming we could make and utilize enough anti-matter to do it and that what we see as the edge here is actually a recognizable edge once you are out there.

0.9C would be reached in only a year and a half for the traveler under constant 1G acceleration. After 2.5 years you would be at .99c, and at a bit over 3.5 years you would hit .999c with a 6x time dilation compared to earth. After 6 years of acceleration it would be .99999c and Earth would be 200 years in the past. As you approach 12 years you would be going 0.9999999999c and Earth would have experienced almost 70,000 years. As you go past 16 years you would be in the millions of years and as you got past 20 years you would be in the billions of years.

Of course doing that may only be feasible with anti-matter energy storage. The next best energy source is fusion energy but it is 2 orders of magnitude less dense. Perhaps some kind of ram scoop would make that route possible but that is going beyond just speculation because we don't know if you can feasibly capture random particles at that speed even assuming you didn't explode from just hitting them in the first place.