Write a science-fiction short story about a male protagonist who accidentally discovers a portal to parallel dimensions while conducting research in his laboratory. As he ventures through different worlds, he realizes that his portal is coveted by malevolent beings who are determined to use its powers for their own nefarious purposes. The protagonist must use his wit, courage, and technological expertise to protect the portal and prevent the impending doom that awaits the universe. The story should contain elements of suspense, action, and exploration, and should highlight the protagonist's transformation as he navigates through different dimensions and encounters diverse life forms.
This prompt doesn't seem malicious.