Interstellar spaceflight will become (barely) feasible once spaceships can reach velocity between 0.02 to 0.1c are possible. Even assuming non-100% conversion efficiency, antimatter has enough energy density to provide this capability.
We're not going anywhere without a revolution in our understanding of the universe.
Now, it's true, there's some slight issues such as radiation, food storage/production, psychological effects, and any random space rocks obliterating your craft, all of which could reasonably turn out to be enough to make it not work. We also don't have a fuel source that can provide 1g of constant acceleration for 80 years for a reasonably sized space ship, though again my memory is that nothing prohibits it from a physics perspective (this is where my knowledge/understanding get prohibitively poor. I'm not sure how the math works if you stick a thousand ion drives to a spaceship that's already in space or if you just need a huge snifter of compressed hydrogen or if you can just use nuclear propulsion but I'm pretty sure that antimatter would do it, if you could bring yourself to waste the money. But maybe we don't have a plausible way to contain it so what do I know).
Maybe I'm remembering wrong, or maybe I glossed over what's currently considered a physics, rather than engineering/economic/materials science problem, but that's what it looked like last I checked.
Edge of observable universe is something like 46 billion light-years away, even at 0.9c thats 50 billion years of travel (22 billion years experienced by the traveller)
But yes, you can travel places by constant acceleration but unfortunately it still dwarfs in comparison to those places out of our reach.
Unfortunately also, the universe is expanding at a rate faster than the speed of light so you actually cant ever reach the edge
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.
Maybe. Beamed propulsion makes a hell of a lot more sense in the solar system.
