I got an idea. It's based on a theory of how black holes are born. The machine has a particle accelerator, which slams particles into a main particle. When all the other particles are fuse into the main particle, it creates a wormhole kind like a black hole, because it feeds on light sourse to grow and remain working. Basically the hole, known as the Nexus, breaks down an object into smaller matter and sucks it through the sub space tunnel to the alien planet, which the scienctists discovered by a space probe. So in the test, the characters successfully created their own star gate, but here's the problem. They can't close it, or they don't know how yet. Because of the facility's light sourse, the Nexus begins to expand, while sending alien life forms to Earth. After the characters escape, the Nexus kept growing and growing, until it almost cover half the sky. But it's still going to grow, until it covers the entire Earth, bringing about a dark age. And the Earth will soon become a new planet with all the alien creatures and new land masses on it, which will bring an end to the human race and Earth animals. That's how the machine works, and that's how the problem occurs. Now how would the main character solve this problem?