Black holes are created usually when something massive (usually a dying star) collapses on itself to create a hole in spacetime. However, I hear that a black hole can be made with objects that aren't so massive. I think that's why everybody was scared that the LHC would be making black holes. I know that technically, the object only has to be compressed to the size of the Schwarzchild radius to be a black hole. So how is it possible to create a black hole without extremely heavy objects?
How to make a black hole using something smaller than a dying star above the Chandrasekhar limit?
In theory, get enough mass (or energy) into a small enough place and you'll make a black hole. You don't need much, just two Planck masses meeting. Fortunately, they would have so little mass they would evaporate instantly.
Because of the mass-energy equivalence, pump enough energy into a small enough place and it may form an event horizon from the mass-energy. This is called a Kugelblitz but I don't know how well the theory has been checked.
Black holes from high energy collisions are what people were worried about from the LHC. Again, Hawking Radiation would cause them to evaporate nearly instantly.
Finally, the extremely high pressure and temperature after the Big Bang may have formed Primordial Black Holes. Some should still be around, but none have yet been detected.
The public's fear of the LHC creating a black hole and destroying the Earth was unfounded. Even if it did happen, and it didn't evaporate due to Hawking Radiation, a black hole is no more powerful than the gravitational energy of the mass put into it, and a few particles don't have much gravity.