If a spaceship could keep going one direction, is there an “end” to the universe like a wall?

There is a little bit more to it than what most people are saying. by our current understanding of physics it is believed that the universe is infinite. So if you had a ship that could move faster than the expansion of the universe you would never reach an end. However in the recent paper by the Planck team they found possible evidence that the universe actually curves in on itself like a sphere meaning that if you could fly in a straight line for long enough you would wide up right back where you started. They say that based on their observations and our current understanding of physics that there is a 99% chance that the universe is curved. But most physicists believe this just means our current theories are wrong.

I think spacetime expansion, difference between the observable universe vs. all universe, and the practicalities of such “trans-universe travel” are irrelevant here. OP’s question is essentially about the topology (“shape”) of the universe.

The answer to that is: we have completely no idea. The universe may be finite or infinite. In case it is finite, it might either just “end abruptly”, be surrounded by some sort of a “wall”, or loop back on itself. There is no data to conclusively support either of those hypotheses.

No one knows, but probably not. We can only see 46 billion light years away, but we have no idea what’s beyond that.

There’s no “end” but, as spacetime expands around you, eventually all stars will expand away at such a rate that you’ll no longer be able to see anything. You’ll be alone and adrift in a totally empty void with absolutely nothing to see ever again. How’s that for a happy thought.

Whats outside the ‘known universe’ is the subject of many debates in many fields – physics, quantum physics, philosophy. Basically no one knows.