It was probably a short story by one of the popular sci-fi writers of the 50s. As I remember it, the story unfolded in a space vehicle where two travelers had embarked on a mission to exceed the speed of light in exploring the universe. Just as they reached their goal the focus shifted to what appeared to be another dimension, and two beings were viewing events in a sort of fishbowl containing our universe. They were lamenting that the contents of their fishbowl would now self destruct due to the success of those space travelers in reaching the speed of light.
The story stuck in my mind all these years, despite the fact that I moved on to many other interests in the intervening decades. I would appreciate it if anybody could identify the author and particulars of that story